management of thrips (megalurothrips distalis...management of thrips (megalurothrips distalis karny)...
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Management of thrips (Megalurothrips distalis Karny) on green gram (Vigna radiata) through
dates of sowing and insecticides
BY
GAJJALA CHARAN KUMAR REDDY
MASTER OF SCIENCE (AGRICULTURE) ENTOMOLOGY
DEPARTMENT OF ENTOMOLOGY
DR. RAJENDRA PRASAD CENTRAL AGRICULTURAL UNIVERSITY, PUSA (SAMASTIPUR) – 848 125, INDIA
2016
Regd. No. M/Ento./141/2014-15 of R.A.U.
Management of thrips (Megalurothrips distalis Karny) on green gram (Vigna radiata) through
dates of sowing and insecticides
BY
GAJJALA CHARAN KUMAR REDDY
A THESIS SUBMITTED TO THE DR. RAJENDRA PRASAD CENTRAL AGRICULTURAL UNIVERSITY, PUSA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF
MASTER OF SCIENCE (AGRICULTURE) ENTOMOLOGY
DEPARTMENT OF ENTOMOLOGY
DR. RAJENDRA PRASAD CENTRAL AGRICULTURAL UNIVERSITY, PUSA (SAMASTIPUR) – 848 125, INDIA
2016
Regd. No. M/Ento./141/2014-15 of R.A.U.
Dedicated
To
My friend
Mr&Mrs A. SUJANA LINGA REDDY
And
My Parents (Amma and Nanna)
“Whose faith, sacrifice and perpetual
affection always inspired me to attain higher values of life”
...CHARAN
ACKNOWLEDGEMENT It is my pleasure to express deep sense of gratitude, respect and heartfelt devotion to Dr.
Rabindra Prasad, Chairman of my Advisory Committee. His sagacious, ingenious, precious,
unabiding interest, valuable guidance, close supervision, untiring effort, painstaking help and
concrete suggestion made my research work a smooth going project. I consider myself fortunate for
getting the golden opportunity to learn under his valuable guidance. I have been infected with
‘work culture’ during his association. Any acknowledgement is an insufficient expression, for all
that I have learnt, while working with him.
I sincerely thank to Dr. Ranjit Ray, Chairman, Department of Entomology, DrRPCAU,
Bihar, Pusa for his kind help during my study and valuable suggestion in research.
It is also my priviledge to extend my sincere thanks and regards to the members of my
Advisory committee: Dr. P. P. Singh, University Professor, Department of Entomology, Dr. A. K.
Mishra, Assistant. Professor, Department of plant pathology, Dr. K. N. Pathak University
Professor & Chairman, Department of Nematology, Dr.RPCAU, Bihar, Pusa, who evinced their
keen interest by not only going through the manuscript critically but also by offering valuable
suggestions.
I am indebted to all the member of the Department of Entomology, Pusa-Dholi Campus
for their cordial and unaccountable help without any reservation in course of investigation.
I especially appreciate Dr. K. K. Sinha, Incharge, Meteorological observatory, T.C.A.,
Dholi for providing informations as and when required.
The co-operation rendered by Mr. Paidi. Satynarayana, Dr. Rahu Kumar Tiwari, Mr.
Anoup Choubaji, Mr Nilamani, Mr. Pilips Lomaro, Mr. Sasidar Yadav, Mr. Pankaj Kumar Ojha,
Mr. Santosh Kumar, Mr. C.R. Kumbhar, Mr. Jitendra Kumar, Mr. Deepk Ingle, Miss. Monika
Srivastav, Mrs.. Smita Kumari, Mr. C. P. Singh, Mr. Rahul Kumar Maurya, Mr. Athul Thampi.
O, Mr. Prabat Kumar, Mr. Alok Kumar, Mr. Kuldeep, Mr. Pankaj Kumar, Mr. Shashi Kumar,
Mr. Tulasi, Mr. Prakash Paudal, Mr. D. Kurre, Mr. Athul, Mr. Bipul, Mr. Gourav, Mr. Lokesh,
Mr.Ajay, Mr, Nitesh, Mr. Prakesh. Mr. Pram. Mr. Ram Kumar. Mr. Munna. Mr. Gyan, Miss.
Sudipa Jha. Miss. Lovely Kumari, Mrs. Ranju Singh students and many friends, is duly
acknowledged.
CONTENTS
CHAPTER NO.
PARTICULARS
PAGE NO.
ABSTRACT : i-ii
I. INTRODUCTION : 1-3
II. REVIEW OF LITERATURE : 4-20
III. MATERIALS AND METHODS : 21-32
IV. RESULTS AND DISCUSSION : 33-48
V. SUMMARY : 49-52
BIBLIOGRAPHY : i-viii
APPENDIX : i-vi
LIST OF TABLES
TABLE NO.
PARTICULARS AFTER PAGE
1. Population build up of thrips, Megalurothrips distalis Karny on mung bean cv. SML668 in relation to weather parameters during summer season 2015-16.
33
2. Correlation coefficient and regression equation between weather parameters (X) and mean number of thrips per plant (Y2).
34
3. Effects of date of sowing on the population of thrips, Megalurothrips distalis Karny on mungbean cv. SML668 during summer season 2015-16.
35
4. Effects of date of sowing on the population of thrips, Megalurothrips distalis Karny per flower of mungbean cv. SML668 during summer season 2015-16.
36
5. Effects of date of sowing on per cent pod infestation caused by thrips, Megalurothrips distalis Karny on mungbean cv. SML668 during summer season 2015-16.
37
6. Effects of date of sowing on grain yield of mungbean cv. SML668 during summer season 2015-16.
38
7. Relative efficacy of synthetic insecticides and plant products (after 1st spraying) against thrips, Megalurothrips distalis Karny on mung bean cv. SML668 during summer season 2015-16.
39
8. Relative efficacy of synthetic insecticides and plant products (after 2nd spraying) against thrips, Megalurothrips distalis Karny on mung bean cv. SML668 during summer season 2015-16.
41
9. Relative efficacy of synthetic insecticides on per cent pod infestation caused by thrips, Megalurothrips distalis Karny on mungbean cv. SML668 during summer season 2015-16.
43
10. Phytotonic effect of synthetic insecticides and plant products on mungbean cv. SML668 during summer season 2015-16.
45
11. Relative efficacy of synthetic insecticides and plant products on grain yield (q/ha) of mungbean cv. SML668 during summer season 2015-16.
46
12. Economics of synthetic insecticides and plant products used as foliar spray for the management of thrips, Megalurothrips distalis Karny on mungbean cv. SML 668 during summer season 2015-16.
47
LIST OF FIGURES
FIGURE NO.
PARTICULARS
AFTER PAGE
1. Population build up and infestation level of thrips, Megalurothrips distalis Karny on mung bean cv. SML668 in relation to weather parameters during summer season 2015-16
34
2. Effects of date of sowing on thrips population and grain yield (q/ha) in mungbean during 2015-16
38
LIST OF PLATES
PLATE NO.
PARTICULARS AFTER PAGE
1. Field view of experimental plot. 21 2. Field view of effects of date of sowing. 22 3. Thrips infested mungbean flowers. 24 4. Healthy pods and deformed pods of mungbean
infested by thrips. 24
RAJENDRA AGRICULTURAL UNIVERSITY, BIHAR PUSA, SAMASTIPUR – 848 125
Name of Student : GAJJALA CHARAN KUMAR REDDY
Post-Graduate Degree Programme : M.Sc. (Ag)
Department : Entomology
Major Subject : Entomology
Minor Subject : Plant Pathology
Major Advisor
Admission No./Registration No
:
:
Dr. RABINDRA PRASAD
M/Ento./141/2014-15
Title of the Research problem : Management of thrips (Megalurothrips
distalis Karny) on green gram (Vigna
radiata L.) through dates of sowing and
insecticides.
ABSTRACT
In order to study the seasonal abundance and management of mungbean thrips,
Megalurothrips distalis Karny through pest monitoring, manipulation in dates of
sowing and relative efficacy of synthetic insecticides and plant products, a series of
filed experiments were conducted during the summer season 2015-16 at the research
farm, T.C.A. Dholi, Muzaffarapur, (Bihar). Results pertaining to different aspects of
the present study viz; seasonal abundance, manipulation in dates of sowing and foliar
spray of synthetic as well as botanical insecticides applied against thrips on
mungbean crop have been abstracted below:
The activity of thrips per plant on summer mungbean commenced from 17th
standard week of April, 2015 and continued to 24th standard week of June, 2015 with
maximum thrips population (5.6 thrips/plant) in the 22nd standard week of June, 2015
when the corresponding maximum, minimum temperature (oC), relative humidity (%)
at 07 and 14 hrs and rainfall (mm) were 40.5, 27.5, 87.7, 46.7 and nil respectively.
The activity of thrips on flower has been initially observed in 18th standard
week of May, 2015 and continued to 20th standard week of May, 2015, respectively
with maximum thrips population of 6.6 thrips per flower during 18th standard week of
May, 2015 when corresponding maximum, minimum temperature (oC), relative
humidity (%) at 07 and 14 hrs and rainfall (mm) were 34.5, 21.3, 89.5, 66.1 and nil
respectively.
Among all the dates of sowing under test, 1st April proved as the most suitable
date of sowing keeping in view to minimize the pest population on plant (2.4
thrips/plant) and flower (1.3 thrips/ flower), plant infestation (11.17%) and obtaining
higher grain yield (14.6q/ha).
Among the synthetic insecticides and plant products under test, significantly
better control of mungbean thrips was achieved imidacloprid 17.8 SL (@0.005%),
when applied twice at fortnightly intervals starting from bud formation stage with
thrips population of 1.4, 1.8 and 2.4 thrips per plant as against 3.6, 4.0 and 4.4 thrips
per plant in untreated control after 1st and 2nd spraying respectively which was equally
effective to dimethoate 30 EC thiomethoxam 25 WG, profenophos 50 EC and
triazophos 35 EC, applied at their test doses respectively.
The phytotonic effect of different treatments under test, two rounds spraying
of imidacloprid 17.8 SL (@ (0.005%), gave the best phytotonic effect with the
maximum mean plant height (84.43 cm), number of braches per plant (9.2) and
average number of pods per plant (48.2), followed by dimethoate, thiomethoxam,
profenophos, triazophos, fipronil, YBSE, spinosad, neem oil respectively.
The highest grain yield of summer mungbean (14.8qa/ha) was obtained with
imidacloprid but did not differ significantly from dimethoate (13.1qa/ha),
thiomethoxam (13.0qa/ha), profenophos (12.3qa/ha), triazophos (11.8qa/ha), fipronil
(10.5qa/ha), spinosad (9.1qa/ha), applied at their test doses as against 7.2q/ha over
untreated control.
The investment of foliar application of imidacloprid, dimethoate,
thiomethoxam, profenophos, triazophos, fipronil, spinosad, proved profitable in
comparison to neem oil and yam bean seed extract at their test doses.
INTRODUCTION
Green gram (Vigna radiata Linn. Wilczek) belonging to Family: Leguminosae
and Sub-family: Papilionaceae is one of the important pulse crop in India. It has been
reported that green gram has been cultivated in India since ancient times. It is the third
most important pulse crop of India after chickpea and pigeon pea. Green gram has
many common names, viz. golden gram, mungbean etc. It is widely cultivated
throughout the Asia, including India, Pakistan, Bangladesh, Sri Lanka, and Thailand.
Mungbean is grown principally for its high protein seeds that are used as
human food, that can be prepared by cooking, fermenting, milling or sprouting, they
are utilized in making soups, curries, bread, sweets, noodles, salads, boiled dahl,
sprouts, bean cake, confectionery, to fortify wheat flour in making vermicelli and
many other culinary products like sabut dhal, dhal, papad, namkeen, halwah, and vari
etc.
Mungbean contains about 24 per cent protein, this being about two third of the
protein content of soybean, twice that of wheat and thrice that of rice. The protein is
comparatively rich in lysine, an amino acid that is deficient in cereal grains but,
cereals are rich in methionine, cystine and cystein, the sulphur bearing amino acids.
So, a diet combining mungbean and cereal grains form a balanced amino acid diet.
Mungbean seeds are rich in minerals like calcium 132mg, iron 6.74mg, magnesium
189mg, phosphorus 367mg, and potassium 1246mg, and vitamins like ascorbic acid
4.8mg, thiamine 0.621mg, riboflavin 0.233mg, niacin 2.251mg, pantothenic acid
1.910mg, and vitamin A. (Anonymous, 2007a). Among pulses, mungbean is favoured
for children and the elderly people because of its easy digestibility and low production
of flatulence.
In India mung production is largely concentrated in five states viz, Uttar
Pradesh, Andhra Pradesh, Maharashtra, Madhya Pradesh and Tamil Nadu. These five
states together contribute for about 65% of total mung production in the country.
There is a distinct change in production pattern of mung across states. Traditionally
Andhra Pradesh, Maharashtra and Madhya Pradesh are major mung producing states.
But there is significant rise in production from other states in recent years particularly,
1
from Tamil Nadu, Uttar Pradesh and Gujarat. Nevertheless, production remained
volatile across the years with respect to most of the states. As per the latest available
estimates, UP and Andhra Pradesh occupy the first two positions, contributing over
40%. Maharashtra contributes about 14% while Tamil Nadu and Madhya Pradesh
account for about 10% and 8.5%, respectively of total production in the country.
Among the grain legumes mungbean is an important pulse crop grown in
summer and kharif seasons in different parts of India in general and Bihar in
particular. It is a short duration crop, fits in various multiple cropping and
intercropping system and grown as catch crop. Besides, serving as food and fodder for
large segment of population and animals, it also fixes atmospheric nitrogen in root
nodules and can be incorporated as green manure in order to enhance the soil fertility.
Pulse crops have immense potentiality to provide food and nutritional security
to large segment of population especially vegetarian people who are mainly
dependent on pulses as source of protein. The available protein to people in India has
come down steeply due to high cost of animal protein on one side and low production
of pulses on the other. Due to insufficient production of pulse the requirement of the
fast growing population results into progressive decline in its availability from 60
gm/capita/day during 1961 to 50 gm/capita/day in 2012-13, while 80-100
gm/capita/day is the minimum requirement for a balance diet. This can be achieved
only by increasing the area, production, and productivity of all pulses including green
gram.
Among grain legumes grown in Bihar, green gram occupies 147.30 thousand
hectare area, with total production 88.38 thousand tonnes and an average productivity
of 600kg/ha (Anonymous,2012). But the productivity has steeply come down in
changing climate scenario due to wide range of biotic and abiotic constraints. Among
biotic constrains, insect pests cause a considerable loss in yield of mung bean. About
60 species of insects are known to attack mung bean during summer and kharif
seasons at different growth stages. Thrips Megalurothrips distalis has been reported
as a major pest causing severe field loss (40-89%) in Punjab (Chhabra and Kooner,
1985). Both nymphs and adults suck the plant cell sap from bud and flowers resulting
shedding of flowers, twisting of pods without grains. High yield reduction was
observed in Bihar particularly during summer season. (Anonymous, 2012).
2
Substantial losses due to thrips could be prevented at minimum cost and
without hazards to man and his environment. Such an approach envisages the
necessity of understanding the ecological background while considering the entire
spectrum of control methodology. Complete details of biotic and abiotic
characteristics of an environment of the pests must be fully investigated and
appropriated. Modern pest management cannot operate without accurate pest
population densities (Ruesink and Kogan, 1975).
The manipulation of the agro ecosystem by altering the date of sowing is
effective tool in combating with the insect population as the minor change in the
microclimate adversely affect the biology and population dynamics of the pest
species. (Chhabra and Kooner 1991, 1993a/b, and 1994).
Keeping in view of the above it is pertinent to know the population build up of
thrips and work out suitable management strategies through cultural and insecticide
application based on ecological consideration. The present investigation has been
undertaken with the following objectives:
1. Population dynamics of thrips on green gram with relation to abiotic
factors.
2. Effects of dates of sowing on the incidence of thrips on green gram.
3. Ascertaining the field efficacy of some synthetic insecticides and plant
products against thrips on green gram.
3
REVIEW OF LITERATURE
The scanning of literature revealed that a little work has been done on the
monitoring of thrips, Megalurothrips distalis (Karny) on green gram. Estimation of
losses caused by thrips, population dynamics in related to abiotic factors and the
control measures like effect of date of sowing, and efficacy of insecticidal molecules
as well as plant products against by thrips on green gram, Vigna radiata Linn.
Wilczek, The important and pertinent work has been done in India and world
reviewed here under.
2.1 Economic status of thrips, Megalurothrips distalis Karny as a pest of
mungbean
Mungbean (Vigna radiata L. Wileczk) is the third most important pulse crop
in India, and also important food legume crop of India cultivated in kharif (monsoon),
rabi (post rainy), and spring/ summer seasons in different agro- ecological zones. In
the North West plain zone of India, comprising of the states of Himachal Pradesh,
Punjab, and Haryana, parts of Rajasthan, Bihar, and Utter Pradesh, mungbean is
grown during the dry season of the year from March to June. Kooner et al., (1982)
recorded the insect pest’s problems in summer mungbean. These authors’s reported
that the thrips, Megalurothrips distalis causes a serious damage to this crop. Chhabra
and Kooner (1983) estimated the losses caused to mungbean by the thrips in Punjab.
Further, Chhabra and Kooner (1985) reported the problem of flower shedding in
mungbean caused by Megalurothrips distalis. A number of insect pests attacked on
mungbean throughout their growth period, which act as limiting factor in production
of crop. Losses to mungbean crop due to insect pests are very high and the
magnitudes of insect pest’s losses to mungbean crop have been estimated by several
workers viz: Panchabhavi and Kadam (1990), Sharma et al., (1991). The insect pests
such as jassids, white fly, thrips, stem fly, epilachna beetle, blister beetle, galerucid
beetle, pod sucking bug, spotted pod borer, and tobacco caterpillar are more
significance on mung bean throughout the country. Several insect pests have been
reported to infest mungbean damaging the seedlings stage and leaves, stems, flowers,
buds and pods causing considerable losses (Sehgal and Ujagir, 1988). In India 64
2
species has been reported attacking green gram right from seedling stage up to pod
formation stage (Lal, 1985). More than twelve species of insect pests were found to
infest mungbean, among them jassids, aphids, white fly, hairy caterpillar, thrips and
pod borers are important. Among the several constrains for low productivity, the
losses due to insect pests are the foremost. The insect pest’s complex of mungbean
has under gone a tremendous change in climate, cropping pattern, insecticide
application pattern and introduction of high yielding varieties (Kooner et al., 2006).
On the other hand, some species which were of minor importance in the past have
become dominant pests, and others that were never reported have appeared. This kind
of shift in the pest complex necessitates a review of the pest complex and economic
loss assessment. The 16 species of insect and mite species during summer season is
with the report of Singh and Karla (1995), however, the status of major pests reported
jassids, stem fly, differed from the present in which only two pests white fly and
flower thrips were reported as major pests. Singh and Singh (1977), Dhuri and Singh
(1983) conducted the preliminary studies on the succession of insect pests in
mungbean. In the recent years, the insect pest’s viz. blister beetle, spotted pod borer
and broad mite assumed the pest status of major pests in mungbean. The flower thrips,
Megalurothrips distalis, a major pest of spring/summer mungbean assumed status of
pests even in kharif season. More than twelve species of insect pests were found to
infest mungbean in the field in Bangladesh (Rahman et al., 2000). Among them thrips
and pod borers are the major insect pests causing considerable losses (Rahman et al.,
1981; Rahman et al., 2000; Hossain et al., 2004). Thrips is associated mostly with the
damage of tender buds and flowers of mungbean. Extensive damage of thrips to
summer mungbean resulted flower shedding and significantly yield loss (Chhabra and
Kooner, 1985; Lal, 1985). Lal (1985) reported 64 species of insect pests that attack
mungbean in the field. Among these sucking insect pests white fly, jassids, and thrips
are the major importance (Khattak et al., 2004). In flowers, both nymph and adults of
thrips nourish on pollen and scratch other flower parts and suck the plant sap oozing
out from the injured plant parts. As a result, flowers drop off and pods formation has
been adversely affected. Sometimes these pests cause total yield loss. Litsinger and
Tommew (1983) classified mungbean insect pests into pre-and post-flowering pests.
They classified bean fly, thrips, flea beetle and leaf folders as pre-flowering pest.
5
Vyas and Saxena (1982) reported that leaf damage in summer was much less
(20.11%-34.04%) than in the rainy season (82.19%-87.56%). Litsnger et al (1980)
reported that 60-80% yield loss in mungbean has been observed when it grown after
rice. The yield loss due to insect pest complex in mungbean varies from 15% to 23%
(Lal and Ahmed, 2001) in Utter Pradesh (Anon, 1997). The increased yield loss 24 to
33 % found may be due to the bean flower thrips, blister beetle, spotted pod borer,
which assumed as major pests in kharif season and cause direct damage to the
reproductive parts as compared to jassids, leaf thrips and semi looper, which are
reported as major pests. (Anon, 1997).
2.2 Population dynamics of thrips, Megalurothrips distalis Karny on green gram
in relation to weather parameters
The survey of literature revealed that the population and infestation level
caused by flower thrips, Megalurothrips distalis Karny. on mung bean varied
significantly in response to weather parameters in different agro climatic regions of
the country and abroad. Weather parameter viz ; temperature (Maximum and
Minimum), relative humidity and rainfall have been found to play an important role in
regulating thrips population and infestation level, but effect do not follow uniformity
trend. Population fluctuation and infestation level of thrips on mung bean was studied
by various workers across the country and abroad. According to Pal et al. (1977)
studied the population fluctuations of thrips on several varieties of mung bean
(V.radiata) in relation to climatic conditions at Jodhpur. They recorded that the ideal
conditions for the outbreak of thrips were about 80 percent R.H., 27.5 to 28.50C
temperature and lower sunshine hours. Singh et al. (1990) conducted field experiment
in New Delhi, during 1987 and 1988 and observed the effect of temperature, relative
humidity, rainfall, wind speed and sunshine on the population build up of the
Caliothrips indicus (Bagnall) on ground nut alone and on ground nut intercropped
with red gram (pigeon pea), green gram (V.radiata) , sorghum, soybean and sesame.
The abiotic factors affected the abundance of thrips. Sahoo and Patnaik (1994)
observed the insects M. Obscurella, Luperodes sp., A. Craccivora, B. tabaci (Genn). ,
Megalurothrips distalis (Karny), C. Indicus (Bagnall), Cydia ptychora (Meyr).
(Leguminivora ptychora), M testualis, M. Vitrata and Helicoverpa armigera (Hub.)
on green gram. Borah (1995a) observed and reported that the main pests of green
6
gram (V.radiata) in Assam in 1993 were A. Craccivora, Amrasca biguttula biguttula
Ishida B. tabaci and Megalurothrips distalis Karny. Their population dynamics were
outlined briefly. The thrips, white flies and jassids appeared in 35th meteorological
week, i.e. from 27th August to 2nd September and remained active till harvest of the
crop. The peak period of activity of thrips and whiteflies was recorded in the 40th
meteorological week. However defoliators were active from 33rd meteorological week
till harvest of the crop (Anon, 1999). Sepswasdi et al. (1991) studied the yield loss
relationships of major insect pests of mung bean (V.radiata) in rice-based cropping
systems in Thailand during 1986-87. Observations of damage and insect density were
made at weekly interval from the vegetative stage to harvesting. Infestation during the
vegetative stage had no impact on yield. Infestation of the noctuid, Spodoptera litura
and Megalurothrips distalis during the end of the vegetative stage to the pod-filling
stage were negatively correlated with grain yield and in a reduction of yield. Gupta
and Singh (1993) conducted an experiment at the farm of the Regional Agricultural
Research and Demonstration Centre, Varanasi U.P during summer and rainy seasons
of 1978 and 1979 against insect pests of mungbean. In summer season observed that
thrips appeared first and population was recorded up to vegetative growth and attained
its peak by 2nd week of May. In rainy season thrips appeared first followed by leaf-
miner; the population of thrips continued to build up and attained peak period by mid
or last week of August. Thrips population was low in rainy season than in summer
season. These clearly indicate that the dry conditions favour the fast multiplication of
thrips. The correlation with abiotic factors also confirms this fact. Thrips showed
significant negative correlation coefficient (r) with relative humidity and significant
positive correlation coefficient with sunshine hours. The multiple correlations were
significant and the weather elements contributed 55.10 per cent on thrips population.
Sreekanth et al. (2002) studied that occurrence and distribution of thrips population
and peanut bud necrosis virus (PBNV) incidence on green gram in Andhra Pradesh.
The occurrence of thrips and incidence of pea nut bud necrosis (PBNV) on green
gram were surveyed in different districts of Andhra Pradesh, India. Nalgonda,
khammam, Warangal, karimnagar, and Medak districts in august 2000 and 2001
(kharif); East Godavari, Srikakulam, and Vizianagarm districts in November 2000 and
2001 (rabi); and Warangal and karimnagr districts were surveyed in April 2001
7
(summer). Thrips palmi was recorded most dominant thrips species (51.0% of the
total population), followed by Scirtothrips dorsalis, Frankliniella schultzei and
Megalurothrips distalis (24.9, 14.9 and 9.3%, respectively). Khan et al. (2011)
reported that the impact of abiotic factors on population fluctuations of insect fauna of
green gram in Sindh, Pakistan. The effect of temperature and relative humidity on
population dynamics of insect pests of mung bean was studied during growing season
of 2005, results revealed that the maximum number of population of thrips was
observed on August 23, 2005 with 1.537+/-0.031per leaf. Temperature had a negative
and significant correlation with thrips (r=-0.860), however the relative humidity
displayed a positive and significant correlation with thrips (r=0.313). Ruesink and
Kogan (1975) pointed out that modern pest management cannot operate without
accurate pest population densities. Acquiring quantitative information about the agro-
ecosystem is a preliminary phase of any basic or applied work on insect plant
interactions. According to Duraimurugan and Tyagi (2014) the field experiments
were carried out to explore the change in pest spectra, their status, succession and
yield losses in mungbean and urdbean under changing climatic scenario. They
observed that the crops during summer were mainly infested by two major insect
pests viz. White fly and bean flower thrips, Megalurothrips distalis. During summer
season in both the crops, as the flowering initiated, flower thrips incidence occurred
and it remained active till pod maturation. The population ranged from 17.0 (43-
49DAS, 20th SMW) to 57.2 (57-63 DAS, 22nd SMW) per 100 flowers in mungbean.
The population of thrips reached its peak at 57-63 DAS (22nd SMW) in mungbean.
Yadav and Singh (2013) conducted the experiment at Agricultural Research farm of
Banaras Hindu University, Varanasi, Utter Pradesh, during 2011-12 on mungbean.
They studied about the seasonal abundance of insect pests on mungbean and its
relation to abiotic factors, resulted that the thrips population was started after
flowering with intensity (0.4/ten flowers) in 33 standard week and gradually increased
and reached its peak in 36 standard week (2.4/ten flowers). Their report was similar to
Chandra and Rajak, (2004); Khan et al., (2011) who recorded thrips population from
flowering to pod filling stge. The correlation coefficient analysis of thrips population
with prevailing weather condition indicated positive correlation with the sunshine and
evaporation and non-significant with temperature, relative humidity, rainfall and wind
8
speed. Yadav and Singh (2006) studied about the forecast model of major insect pests
of mungbean. The forecasting model of major pests developed on the relationship
between insect density (thrips, jassids and white flies) on mung bean and the
prevailing weather factors (maximum temperature, minimum temperature, maximum
R.H., minimum R.H. and rainfall) during summer and rainy seasons of 2003 and
2004. Population dynamics of major mung bean pests were studied at two
experimental sites i.e. I.I.P.R., Kanpur and Farmers fields in Etowah, (Uttar Pradesh).
Thrips population at Kanpur location during summer had a significant positive
correlation (0.574) with maximum temperature, whereas, a non-significant negative
effect of maximum humidity and rainfall was noticed along with a slight positive
influence of minimum temperature and humidity when the cumulative effect of
weather on the population build up was studied. Chaudhuri and Senapati (2004);
Badjena and Mandal (2005) found positive association with temperature during
summer. A unit increase in maximum daily temperature caused an increase of 1.97
thrips per plant. The multiple correlations were non-significant as weather elements
contributed only 39.2 percent towards coefficient of determination for thrips
population. At Etowah location, maximum and minimum temperatures played a
positive significant role in building up the thrips population (r = 0.548 and 0.642).
The remaining other variables did not signify their influence on pest population. The
cumulative effect of weather on population build up of thrips was found to be
significant as maximum temperature responded positively and minimum temperature
negatively. A unit increase in maximum daily temperature rendered an increase of
2.67 thrips/plant while in contrary to this, a unit increase in minimum daily
temperature resulted with a decrease of 1.98 thrips/plant. Interestingly, the coefficient
of determination was found to be significant as weather elements contributed 64.3
percent on thrips. As regards to thrips population at Kanpur during rainy season
maximum temperature played a significant role in increasing the pest. A unit increase
in maximum daily temperature caused an increase of 1.89 thrips per plant. Rainfall
played a significantly negative role. A unit increase in the rainfall caused a decrease
of 1.15 thrips per plant. The coefficient of determination was found significant as
weather elements contributed 53.3 percent on thrips population. Negative and
significant association of this pest was also reported by Kumar and Nath (2005).
9
Thrips population at Etowah location during rainy season revealed that
maximum temperature had a positive and significant role in building up of the pest
population. The remaining other variable had their negative effect on pest population
to decrease except, minimum temperature. A unit increase in maximum daily
temperature caused an increase of 0.858 thrips per plant. A unit increase in rainfall
resulted with decrease of 1.065 thrips per plant. The overall variability explained by
all the variables influenced up to 71.5 percent thrips population build-up. These
results indicated significantly positive effect of maximum temperature on thrips
population in both the seasons at Kanpur and Etowah locations and effect of
minimum temperature was not so consistent. The role of humidity and rainfall was
found non-significant.
2.3 Management of thrips, Megalurothrips distalis Karny on green gram through
manipulation in date of sowing
Manipulation in dates of sowing times takes advantage of the period of
absence of the pest on the crop or synchronies between susceptible stage of the crop
and the most inactive period or the lowest population of the pest, which does not
cause the economic loss and practice more meaningful if it is based on the
information obtained through pest surveillance. According to Hossain et al. (2009) an
experiment was conducted at Pulses Research Centre, Ishduri, Pabna, Bangladesh
during kharif-I to find out the insect pests attacking mung bean crop sowing at
different dates to determine the optimum dates of sowing. Among, thrips population
in mung bean flower differed significantly depending on sowing dates, ranging from
1.20 thrips per flower per day to 3.98 thrips per flower per day. The highest thrips
population (3.98 thrips/flower/day) was observed in crop sown on 14th February
followed by February 21 and February 28 sowings. The lowest population (1.20
thrips/flower/day) was observed on crop when sowing was done on 6th March which
was identical to all the sowings of March. In April sowing crops, thrips population
increased than those of March sowing crop. It is seen that thrips population was
higher in early (February 14 to March 06) and late (April 13 and onwards) sowing
crops than mid sowings (March 13 to April 10). Grain yield of mungbean varied to
the variation of sowing dates and insect pest infestation. They also observed that both
the early (February14 to March 06) and late sown (April 13 and onward) crops
10
received higher insect pest’s infestation and recorded lower yield. But mid sown
(March 13 to April 10) crops received less insect pest’s infestation and produced
higher yield. Relationship between flower thrips population and yield showed a
negative correlation (y = - 228.61x + 1485.2; R2 = 0.2596), indicating the increase of
thrips population in flower causes a progressive loss in yield. For each
thrips/flower/day increase, there was a decrease of yield by 228.61percent. The
correlation coefficient (r) was 0.509 and the contribution of regression indicated that
25.96percent yield loss occurred by flower thrips. Sreekanth et al. (2002) studied on
the effect of sowing date on T.palmi population and peanut bud necrosis virus
(PBNV) incidence in green gram were conducted at the National Bureau of Plant
Genetic Resources, Regional Station, Rajendranagar, Hyderabad, Andhra Pradesh,
India. Sowings were performed in monthly intervals between October 2000 and
September 2001. It could be inferred that early or timely (second fortnight of May to
first fortnight of June) sowing of green gram in kharif and late October sowing in
Rabi would help in containing the thrips infestation and PBNV incidence. The usual
sowing dates in rice fallows and summer sowings need not be disturbed. However,
irrespective of sowing date, the maximum T. palmi population build up coincided
with the beginning of flowering stage of the crop phenology. Satyavir and Singh
(1985) studied the pest incidence and yield losses of moth bean sown on four dates in
kharif, 1983 and 1984 at CAZRI, Jodhpur and reported loss in seed yield from 15 to
50 per cent in 1983 and 14 to 37 per cent in 1984. The moth bean sown on 1st or 2nd
week of July escaped insect attack and produced higher seed yield.
2.4 Relative efficacy of synthetic insecticides and plant products as foliar spray
against mungbean thrips, Megalurothrips distalis Karny.
A number of insecticides and plant products have been tried as foliar spray
and soil application by several workers both in India and abroad for managing thrips,
Megalurothrips distalis Karny. on mung bean with varying degree of success.
According to Chhabra and Malik (1992) tested 70 entries of summer mung bean
(V.radiata) germplasm and breeding material for resistance to Megalurothrips distalis
and inflorescence deformity. SML77, UPM82-4 and Pusa 107 were identified as
‘donors’ for use in a breeding programme. The development of Megalurothrips
distalis on 11 promising summer mung bean (V.radiata) genotypes was studied by
11
Chhabra and Malik (1992) and found that the development was prolonged on the
resistant genotypes SML 77 and UPM 82-4, and adult longevity was shortened.
Chhabra and Kooner (1983) estimated the loss caused to mung bean by the thrips in
Punjab. They also reported the problem of flower shedding in this crop caused by
Megalurothrips distalis. They further tested the efficacy of about a dozen of
insecticides for the control of thrips and found that four insecticides viz., dimethoate,
malathion, phosphamidon, and oxydemetonmethyl, performed better out of the 11
insecticides tested for their efficacy to control the thrips, Megalurothrips distalis on
summer mung bean during 1982-1984. In between the treatments higher doses of
malathion, dimethoate, and oxydemeton methyl had recorded significantly low
population of thrips in comparison with their lower doses. Increases yield compared
with the control during trails ranged from 85 to 89 per cent during 1982, 26 to 96 per
cent in 1983 and 5 to 94 per cent in 1984, respectively. Yadav et al. (1979) studied the
effectiveness of sixteen insecticides against the insect pests of mung bean.
monocrotophos 0.04 per cent, endosulfan 0.07 per cent, Neem seed kernel 2.0 per cent
as spray and dust, phosalone 0.04 per cent, carbaryl 0.05 per cent were found most
effective for control of thrips on mungbean. Irulandi and Balasubramanian (2000)
conducted a field experiment in Tamil Nadu in 1995-96 to determine the effectiveness
of a number of botanical insecticides against Megalurothrips distalis in comparison
with monocrotophos. Neem seed kernel extract at 5 per cent was found most effective
against M.distalis, followed by neem oil at 2 percent. Ekesi et al. (2001) reported the
time of application of entomopathogenic fungus, Metarrhizium anisopliae for the
control of legume flower thrips, Megalurothrips sjostedti on cowpea at Nairobi,
Kenya. One application of M.anisopliae at flower bud stage and two applications at
flowering ensured M.sjostedti population in check with a concomitant increase in
cowpea. Afzal et al. (2002) evaluated the efficacy of four insecticides, viz., lmicon 25
WP (imidacloprid) at 200g/acre, pride 25 WP (buprofezin) at 600g/acre, digital 20 EC
(fenpropathrin) at 250 ml/acre, and taophos 25 EC (quinalphos) at 250 ml/acre, was
evaluated in Faisalabad, Pakistan, against white fly, B.tabaci, and black thrips,
C.indicus on mung bean cultivar NM-92, (V.radiata). All the insecticides were found
to be effective against whitefly and some were effective against black thrips. On a
numerical basis, however, a spray of lmicon 25 WP (imidacloprid) at 200g/acre was
12
found to be most effective both for whitefly and black thrips. Dhamaniya et al. (2005)
studied that the bio efficacy of insecticides, out of them dimethoate @ 0.03 per cent
was found highly effective for the control of jassids, E.motti, and thrips, C.indicus
followed by monocrotophos @ 0.036 per cent, while phosphamidon @ 0.03 per cent
was found highly effective against white fly, B.tabaci followed by dimethoate @ 0.03
per cent. The azadirachtin @ 5ml/litre of water was found least effective for the
control of jassid, white fly and thrips. Sreekant et al. (2003) tested the schedules of
imidacloprid which significantly reduced the Thrips palmi population and disease
incidence on mung bean (cv. K-851). Imidacloprid @ 0.0035 per cent as seed
treatment, followed by imidacloprid @ 0.008 per cent as foliar spray at 15, 30 and 45
days after sowing exerted superior control of T.palmi and ground nut bud necrosis
virus (GBNV) incidence (62.2 and 37.4 per cent reduction) compared with the control
during kharif and 70.5 and 55.1 per cent reduction during Rabi seasons, respectively,
followed by imidacloprid @ 0.0035 per cent as seed treatment, together with
imidacloprid @ 0.008 per cent as foliar spray at 15 and 30 DAS 60.8 and 36.8 per
cent and 69.6 and 52.6 per cent thrips population. Though, imidacloprid @ 0.0035 per
cent seed treatment, followed by imidacloprid @ 0.008 per cent as foliar spray at 15,
30 and 45 DAS recorded highest yield than the rest of the treatments. Kumar et al.
(2007) studied relative efficacy of newer insecticides against insect pests of urd bean
using seed treatment in combination with foliar application during kharif 2005 at
Faizabad. Experiment results reveals that the insecticidal treatments significantly
reduce the population of various insect pests. Spraying of lambda cyhalothrin @ 0.04
per cent was most effective in reducing population of thrips, Megalurothrips distalis
Karny 2.0/25 flowers and seed treatment with thiomethoxam 2g/kg seed + foliar spray
of triazophos @ 0.04 per cent was comparatively more effective against thrips. Rao
and Rao (2007) studied the effect of certain seed dressers and foliar sprays against
thrips, Thrips palmi of mung bean (Vigna radiate) and their impact on grain yield
during the summer seasons of 2002 and 2003 at Regional Agricultural Research
station, Jagitial, Andhra Pradesh, India. Foliar spray of monocrotophos @ 0.05 per
cent and dimethoate @ 0.06 per cent were found to be highly effective in controlling
the thrips and recorded maximum grain yields and per cent increase in grain yield in
green gram. The seed dressers, thiomethoxam (70 WS) and imidacloprid (70 WS)
13
both at 3g/kg seed were moderately effective against thrips. The plant growth and
vigour were good in thiomethoxam and imidacloprid seed treated plots. Kooner et al.
(2007) conducted experiment to know the efficacy of different insecticides as foliar
sprays against bean thrips, Megalurothrips distalis Karny in mung bean. Three
insecticides viz. triazophos 40 EC, ethion 50 EC, and endosulfan 35 EC, along with
standard insecticide dimethoate 30 EC, used as foliar sprays against bean thrips,
Megalurothrips distalis in mung bean variety SML 668 during summer 2002, 2004
and 2005 at Punjab Agricultural University, Ludhiana. All the insecticides were found
effective in reducing the incidence of bean thrips and they significantly increased the
yield during these years. However, triazophos 40 EC, at 1.5L/ha was most potent
treatment in reducing the damage, resulting in significantly higher mean yield (1393
kg/ha) as compared to control (1162 kg/ha) during the three years, followed by
endosulfan 35 EC at 2.25L/ha and ethion 50 EC at 2.0L/ha (1360 and 1334 kg/ha,
respectively) which did not differ significantly between themselves. Foliar application
of triazophos 40 EC fetched the highest net returns (Rs.2717/ha) over control. Kooner
et al. (2006) studied that the mung bean crop is attacked by a number of insect pests.
The most serious pest problems include the white fly, Bemisia tabaci, bean thrips,
Megalurothrips distalis, gram pod borer, Helicoverpa armigera and legume pod
borer, Maruca vitrrata. Among these seventy entries of summer mung bean were
screened in 8 trails against M.distalis, where NM 92 and Pusa 2032 were identified as
resistant and could be used in hybridization programme. The insecticides tested
against M. distalis, hostathion (40 EC) and triazophos at 1500ml/ha each gave
excellent control of the pest. Effect of various cultural practices, viz. tillage, residue,
irrigation, fertilizer, date of sowing, seed rate, mulching, irrigation, variety and
spacing on M.distalis was studied. Narrow row-to-row spacing of 20 cm attracted
more thrips compared with wider spacing of 30 cm. Lesser fertilizer and more
irrigations were effective in lowering thrips population but this findings needs further
testing. Other agronomic practices did not have any significant effect on the
population of thrips. Shah et al. (2007) a field experiment was conducted in
Bahawlpur, Pakistan, during the 2005 kharif season to study the efficacy of
imidacloprid, acetamiprid, buprofezin, and thiomethoxam on jassids, white flies, and
thrips infesting mung bean cv. NM-92. Among acetamiprid gave maximum plant
14
height and number of pods per plant while imidacloprid gave the highest number of
seeds per pod, 1000- seed weight and seed yield. Chhabra et al. (1986) studied that
the efficacy of insecticides viz; dimethoate at 75g a.i, malathion at 125g a.i,
oxydemeton- methyl at 75g a.i, and phosphamidon at 75g a.i./ha against thrips on
mung bean was assessed in field studies in Punjab, India, in 1985. All four treatments
resulted in significantly fewer thrips, a lower number of dropped flowers and
decreased incidence of flower deformity. The treatments ultimately increased grain
yield and net profit. Among dimethoate was the most effective treatments giving
yields of 1270kg/ha. Chander and Yeshbir (1989) conducted a field trial in Delhi,
India, in 1986-87 and found foliar spray of monocrotophos at 0.04 per cent was the
most effective of several insecticidal treatments against Megalurothrips distalis
infesting mungbean (Vigna radiate), giving complete morality in 4 days. Spraying
with monocrotophos at 0.04 per cent, dimethoate at 0.03 per cent and chlorpyrifos at
0.05 per cent at flowering stage reduced infestation of Euchrysops cnejus and Maruca
testulalis. Hossain (2013) conducted a trial to develop insecticide application schedule
for the effective management of thrips and pod borer attacking mungbean during
kharif-I season of 2010 and 2011. Foliar application of imidacloprid at different
growth stages of mungbean suppressed flower infestation and thrips population
significantly in both the years. Both the single and double spraying of imidacloprid
starting from flowering to seed developing stage significantly reduced flower
infestation and thrips population. Hossain et al. (2004) reported that double spraying
of imidacloprid reduced more flower thrips in mungbean than single one. Between
two double sprayed treatments, spraying at 35 DAS (100% flowering) + 42 DAS
(100% podding) reduced more flower infestation and suppressed more thrips
population than spraying at 42 DAS (100% podding) and 49 DAS (seed developing
stage). After 24 hrs of spray application, reduction of flower infestation and thrips
population was more than 80% in all the treatments in both the seasons. Among the
tested insecticides, imidacloprid showed significant performance in reducing flower
infestation and thrips population reduction. Azam et al., (2008) a field study was
carried out at Bangladesh Agricultural Research Institute (BARI) farm during March
to August 2005 to find out the most appropriate management practices against thrips
of mungbean. The experiment consisted of seven treatments of various management
15
practices. The treatments showed significant influence on the incidence of thrips. The
results showed that the (spraying of shobicron 425 EC @ 20 ml/L of water at 20
DAS and at 35 DAS) had the lowest number of thrips (2.5 per 5 leaves) whereas the
highest number of thrips (5.2 per 5 leaves) was recorded from untreated control.
Similarly, spraying of shobicron (425 EC) @ 20 ml/L of water at 20 DAS and at 35
DAS ensured the highest reduction of thrips infestation (57.42%) over control
followed by seed treatment with furadan 5G @ 4% before sowing recorded 46.15%
reduction over control. Similar performance of furadan 5G against thrips was reported
by Olowe et al. (1987). They reported that the lowest number of thrips was recorded
from furadan treated plots and also 46% population reduction over control. The
reduction of thrips infestation (40.72%) from spraying of cymbush 10 EC over control
was also reported by Anon. (2000). Iqbal et al., (2013) conducted a field trial to
evaluate combination of seed treatment with imidacloprid (confidor 70 WS) and spray
with detergent and for insecticide sprays viz: imidacloprid (confidor 20% SL),
acetamiprid (acelan 20% SL), thiomethoxam (actara 25 WG) and acephate
(commando 75 SP) against sucking insect pests on mungbean, at Arid Zone Research
Institute (AZRI), Bhakkar during 2012. The results regarding thrips population, per
flower, in different treatments, revealed a highly significant difference among the
treatments, it was found that spray with acephate was the most effective and resulted
in the maximum control of thrips-population followed by spray with acetamiprid with
thrips population of 1.64 and 2.337 per flower, respectively. The maximum reduction
in thrips population (0.897%) was recorded in the plots treated with acephate which
was better than 0.776%, 0.397%, 0.242%, 0.035% reduction of test insect with
acetamiprid, imidacloprid, actara and combination of seed treatment and detergent,
respectively, at 72 hour after spray. Efficacy of insecticides remained the same at 168
hours after application. The overall effect of combination of seed treatment and
detergent on the population of thrips was not pronounced in the post treatment
observations. The effectiveness of combination of seed treatment + detergent was
found to be the minimum with 4.191 thrips per flower followed by spray with Actara
with 3.684 thrips per flower as against 4.578 thrips per flower in control treatment.
The response of spray with imidacloprid and spray with acetamiprid was found
intermediate with thrips population of 3.005 and 2.337 per flower, respectively. The
16
application of acephate showed the maximum mortality of the thrips. The present
findings are not in accordance with the results of Koenig et al. (2001) who found that
actara (thiomethoxam) 25 WG proved an excellent controlling insecticide against
thrips. In the present study effectiveness of actara was minimum which supports the
finding of Khattak et al. (2004) who investigated that actara (thiomethoxam) 25 WG
lost its efficacy against thrips in 240 hour after spray. Afzal et al., (2002) studied
about the efficacy of four different insecticides viz., imicon (imidacloprid) 25 WP @
200 gm/acre. pride (buprofezin) 25 WP ((I) 600 gm/acre, digital (fenpropathrin) 20
EC @ 250 rnl/acre and taophos (quinalphos) 25 EC @ 250 ml/acre, was tested against
whitefly, Bemisia tabaci (Genn.) and Black thrips, Caliothrips indicus on Mung bean.
Vigna radiata (L.). The data revealed that imicon after first application with mean
population of 2.33 black thrips/ leaf proved to be the best followed by taophos with
2.67 black thrips/leaf. After second spray, imicon showed the same results with 3.50
black thrips/leaf followed by digital with 6.25 black thrips per leaf. The overall of two
sprays revealed that imicon with 2.75 black thrips per leaf as the best treatment
followed by digital with 4.79 black thrips per leaf.
2.4.1 Effect of synthetic insecticides and plant products on growth, yield
attributing parameters of mungbean and economics.
Shah and Maula (2010) conducted experiments for evaluation of some IPM
packages against insect infestation of mungbean at the experimental field of Regional
Wheat Research Center, BARI, Shyampur, Rajshahi district in Bangladesh during
Kharif-l of 2008 and 2009. According to them the grain yield in 2008 did not show
significant difference among the treatments but numerically higher yield obtained
from the seed treatment with imidacloprid 70 WS (5g/kg seeds) + poultry manure
(3t/ha) + 8 sequential release of bio-control agents (Trichogramma chilonis + Bracon
hebetor) + spray with detergent @ 2g/L of water (910.00 kg/ha) where as lowest was
untreated control. (706.67 kg/ha). In 2009, the highest grain yield also obtained from
the seed treatment with imidacloprid 70 WS (5g/kg seeds) + poultry manure (3t/ha) +
8 sequential release of bio-control agents (Trichogramma chilonis + Bracon hebetor)
+ spray with detergent @ 2g/L of water (920.00 kg/ha) which was significantly
different from remaining all the treatments. The lowest yield was found in untreated
control. (721.33 kg/ha). Total variable cost ranged from 0 (zero) to Rs.3475/ha where
17
the minimum and maximum were in untreated control and seed treatment with
irnidachloprid 70 WS (5g1kg seeds) + poultry manure (3t/ha) + spray with quinalphos
25EC (Minalux-25EC) @ 1ml of water respectively. The highest value of additional
yield over control was found in the seed treatment with imidacloprid 70 WS (5g/kg
seeds) + poultry manure (3t/ha) + 8 sequential release of bio-control agents
(Trichogramma chilonis + Bracon hebetor) + spray with detergent @ 2g/L of water
treated plot followed by seed treatment with imidacloprid 70 WS (5g/kg seeds) +
poultry manure (3t/ha) + sequential release of bio-control agents (Trichogramma
chilonis + Bracon hebetorj + spray with crashed neem seed extract @ 50g/L of water,
and seed treatment with imidachloprid 70 WS (5g/kg seeds) + poultry manure (3t/ha)
+ spray with quinalphos 25EC (Minalux-25EC) @ 1ml of water in both 2008 and
2009 season. The maximum marginal benefit cost ratio (MBCR) was obtained from
the seed treatment with imidacloprid 70 WS (5g/kg seeds) + poultry manure (3t/ha) +
8 sequential release of bio-control agents (Trichogramma chilonis + Bracon hebetor)
+ spray with detergent @ 2g/L of water treated plot. followed by seed treatment with
imidacloprid 70 WS (5g/kg seeds) + poultry manure (3t1ha) + sequential release of
bio-control agents (Trichogramma chilonis + Bracon hebetorj + spray with crashed
neem seed extract @ 50g/L of water; and seed treatment with imidachloprid 70 WS
(5g/kg seeds) + poultry manure (3t/ha) + spray with quinalphos 25EC (minalux-
25EC) @ 1ml of water treated plot in both the year. Chhabra and Kooner (1986)
conducted experiments on different doses of malathion, oxydemeton methyl and
phosphomidan against thrips, Megalurothrips distalis Karny on summer mungbean.
Among them per cent increase in yield over control was highest 59% in the treatment
75 g a.i/ha of dimethoate, followed by phosphomidan (50.3%), oxydemeton methyl
(48.4%) and malathion (48.2%). Maximum net profit of Rs. 2033 was bagged by the
treatment dimethoate 75 ga.i/ha followed by phosphomidan (Rs. 1731/ha),
oxydemeton methyl (Rs. 1661/ha) and malathion 125 g a.i/ha (Rs. 1662/ha). Hossain
(2013) conducted an experiment to develop insecticide application schedule for the
effective management of thrips and pod borers attacking mungbean during Kharif- I
season of 2010 and 2011. The yield of mungbean differed significantly depending on
the level of suppression of thrips population and pod borer infestation by spraying
imidacloprid at different growth stages. During kharif-I, 2010, significantly the
18
highest yield (1798 kg/ha) was obtained from the plots sprayed twice with
imidacloprid at 42 DAS (100% podding) and 49 DAS (seed developing stage) which
was statistically identical to double spraying at 35 DAS (100% flowering) and 42
DAS (100% podding stage). The lowest yield (1595 kg/ha) was recorded from
untreated control plots. All the single sprayed treatments at 100% flowering, 100%
podding and seed developing stages at 35, 42, and 49 DAS gave statistically identical
and lower yield which was lower than double spraying. In the next year the yield was
lower than that of the previous year. In double spraying plots the yield of mungbean
was the highest (1457 kg/ha) against the lower yield in the single treated plots. The
net income and marginal benefit cost ratio depending on cost of insecticidal
application and insect pest control particularly thrips and pod borer. During kharif-I
2010, the highest net income (Rs. 10030/ha) was recorded from double spraying at 42
DAS (100% podding) and 49 DAS (seed developing stage) followed by double
spraying (Rs. 7510/ha) at 35 DAS (100% flowering) and 42 DAS (100% podding
stage). The highest monetary benefit (4.67) was obtained from double spraying at 42
DAS (100% podding) and 49 DAS (seed developing stage) which was close to single
spraying (4.19) at 42 DAS (100% podding stage). During kharif-I (2011), the highest
net income (Rs.12370/ha) was recorded from double spraying at 35 DAS (100%
flowering) and 42 DAS (100% podding stage) and nearly the same net income at 42
DAS (100% podding). Accordingly the highest monetary benefit (5.75) was found
from double spraying at 35 DAS (100% flowering) and 42 DAS (100% podding
stage) followed by single spraying (4.83) at 42 DAS (100% podding). Azam et
al.(2008) observed that the seed yield of mungbean also differ significantly by the
different treatments, the highest seed yield (950.50 kg/ha) was recorded from seed
treatment by @ 4% before sowing which was statistically similar with spraying of
shobicron 425 EC @ 20 ml/L of water at 20 DAS and at 35 DAS (915.2 kg/ha). The
lowest seed yield was recorded from the untreated control and it was statistically
different from other treatments. The highest rate of increasing seed yield (60.87%)
over control was obtained from seed treatment with furadan 5G treatment followed by
shobicron 425 EC (54.91%). The third and fourth highest increase (38.85% and 35.57
%) was recorded from the application of spraying of cymbush 10 EC @ 1 ml/L of
water at 20 DAS and at 35 DAS and neem seed oil @ 10 ml of water + trix @ 5 ml/L
19
of water at 20 DAS and following spray at an interval of 10 days and continued up to
the maturity of the crop, respectively. There was strong negative linear regression (y=
1219.1 – 127.7x) was found between the number of thrips and yield for different
treatments, which indicated that higher number of thrips conversely lower the total
yield. The correlation coefficient (r) was – 0.91 and the contribution of the regression
(R2) were 0.82. Patel and Srivastava (1990b) concluded that application of carbofuran
and carbosulfan had boosting effect on plant growth which was very well observed
through increase in plant height, root weight, length of tap root as well as number of
leaves per plant in cowpea and green gram. Patel and Srivastava (1990) and Patel and
Sudhani (1990) studied the phytotonic effect of chemical insecticides on cowpea and
mungbean. Besides controlling the target pests, these also induced direct or indirect
effect on growth and development of crop plants. All the parameters of plant growth
showed significant difference between treated and untreated plots on the number of
leaves per plants, shoots length and seedling weight.
20
MATERIALS AND METHODS
In order to determine the seasonal abundance and to explore the possibilities
of management of flower thrips, Megalurothrips distalis Karny on mungbean through
various tactics viz; different dates of sowing and foliar spray of insecticides and plant
products, a series of field experiments were conducted at the research farm of T.C.A,
Dholi Muzaffarpur, Bihar, India during summer season of 2015-16. The materials and
methods varied from experiment to experiments. However, certain techniques and
observations followed were common for majority of the experiments. Accordingly,
methodology adopted during the experimentation is presented as under:
3.1 Population dynamics of thrips, Megalurothrips distalis Karny on mungbean
In order to study the population dynamics of thrips on mungbean in relation to
abiotic factors, fixed plot survey was conducted at the research farm of T.C.A. Dholi
Muzaffarapur, (Bihar) during summer crop season 2015. SML 668 was grown as test
variety which was sown in a plot of 10 x 10 sq.m. area during last week of March
following normal agronomic practices except insecticidal application. The crop sown
on 24th March, 2015.
The observation on pest activity was initiated at weekly interval throughout
the crop season starting from first week of May, 2015 to maturity of the crop. The
observations with regard to number of thrips were recorded on five randomly selected
plats, from each plant three leaves, viz; one each from top, middle, and lower canopy
respectively. Thrips population were also recorded on 20 randomly selected flowers.
The population was recorded in the early morning hours during 6.30 to 8.00 am. The
collected leaves and flowers were immediately kept in a polythene bag containing
ethyl acetate soaked cotton bolls to kill the thrips enabling easy counting. The
population was counted through hand lens having 10X magnification. The data so
obtained, were finally used to work out the average number of thrips per plant by
using following formula.
Mean no. of thrips per leaf = ⋯
Where “n” denotes number of thrips per plant numbering 1 to 5
3
Plate No.1 Experimental Plot
The observations on flower infestation due to thrips were also worked out by
counting 20 randomly selected flowers across from the plot.
The influence of abiotic factors viz. temperature oC (maximum and minimum),
relative humidity (%) at 07 and 14 hrs, rainfall (mm) on the fluctuating population
and infestation of thrips was also determined. For this purpose, these meteorological
parameters were recorded at weekly interval. By using these data correlation and
regression analysis between abiotic factors, population of thrips and its infestation on
leaf were worked out. Meteorological data were obtained from meteorological station,
T.C.A. Dholi.
3.2 Effects of dates of sowing on the incidence of thrips on green gram.
In order to explore the possibility by management of thrips on mungbean
through manipulation in sowing time, a field trail was conducted in RBD at the
research farm, T.C.A. Dholi, Muzaffarapur (Bihar) during 2015. The mungbean
variety SML668 was used as test variety with five dates of sowing at ten days
intervals, starting from March 24th, 2015.
All the treatments (sowing times) were replicated four times. All the cultural
practices were followed uniformly as per the local recommendation excepting that no
insecticide was applied at any stage of the crop. The seed were sown in row at plant
spacing of 30 x 10 cm with a plot size of 2.0 x 1.80 m.
Observation pertaining to the thrips population was recorded on three leaves
on each plant one from top, middle, and lower in five randomly selected plants before
commencement of flowering. Thrips population was also assessed on 20 flowers
randomly collected from two middle rows from each plot at weekly intervals using a
10X lens, till podding stage. Adults were swift in movement and many times fly away
while counting. Therefore, to avoid errors in thrips count only nymphs were
considered for recording observations. The data obtained in successive observations
were added to obtained cumulative mean number of nymphs per leaf and flower.
At maturity, all the pods were collected from 10 randomly selected plants
from central four rows of each plot and examined. The infested (deformed pod) and
22
Plate No.2 Field view of effect of dates of sowing
total numbers of pods were counted and the per cent pod infestation was determined
using the following formula:
Percent Pod infestation =
100
Finally seed yield was recorded plot wise at the time of harvesting, and
converted into quintals per ha. Test weight of 100 seeds also calculated and data so
obtained were subjected to statistical analysis.
3.3 Management of mungbean thrips, Megalurothrips distalis Karny through
foliar spray of insecticides and botanical insecticides.
In order to ascertain the field efficacy of chemicals and botanical insecticides
used as foliar spray against thrips (Megalurothrips distalis Karny) on mungbean, a
field trail in RBD was conducted at the research farm of T.C.A. Dholi, Muzaffarapur
(Bihar) during summer season crop 2015-16. There were altogether ten treatments and
each treatment was replicated thrice. The treatment details are given below:
Treatment No. Insecticide/ Plant products Doses of application
T1 Spinosad(45% SC) 0.045%
T2 Triazophos (35%EC) 0.04%
T3 Thiomethoxam (25% WG) 0.025%
T4 Profenophos (50% EC) 0.05%
T5 Imidacloprid (17.8%SL) 0.005%
T6 Fipronil (5%SC) 0.05%
T7 Neem oil 3%
T8 Yam bean seed extract 5%
T9 Dimethoate (30%EC)(standard check) 0.03%
T10 Control -
23
The mungbean variety SML 668 was grown as a test crop and sowing was
done on 24th March 2015. The seed sown in rows at plant spacing of 3010 cm with
a plot size of 2.01.80 m. The spray formulations were prepared from the
commercially available material except yam bean seed extract and all the treatments
were sprayed with manually operated knap sack sprayer. All the crop management
practices were followed to maintain healthy crop growth and no insecticides or plant
products other than those included in the trail was applied. All the treatments were
applied twice at fortnightly interval starting from bud formation stage.
Observations with regard to the thrips population would be recorded on 20
randomly selected flowers from the each plot. Pre-treatment observations were
recorded one day before spray and post treatment observations were recorded at 1, 5,
10 days after each spray during morning hour before 7.30 a.m.
The mean per cent deformed pod will be recorded by counting number of
infested pods in total number of pods per plant. The observations were recorded on
ten randomly selected plants in each treatment at the time of pod maturity stage.
Influence of foliar application of different synthetic insecticides and plant
products on plant growth of mungbean was assessed by taking mean plant height and
mean number of branches per plant as the growth parameters. For plant height as well
as number of branches per plant, a sample of five randomly selected plants from each
plot were taken into account at 10 days after second spraying 65 days after sowing
(DAS).
Treatment effect on yield attributing characters of mungbean was assessed
when the crop reached maturity. For this purpose, five randomly selected plants from
each plot were harvested and observation with regards to mean number of pod per
plant and 100 grain weight were recorded. Plot wise grain yield was recorded after
harvesting and percent increase in yield over control was calculated for assessing the
yield performance of different treatments.
Data so obtained from above observations were finally subjected to statistical
analysis.
24
Plate No.3 Thrips infested flowers
Plate No.4 Healthy pods Deformed pods without grains
The details of insecticides used during the investigations are given below:
Spinosad 45%SC
Chemical name :- Spinosad
Trade name :- Comfortis
Source :- Bayer Crop Science
IUPAC Name :
Spinosyn A :- (2R ,3aS, 5aR, 5bS, 9S, 13S, 14R, 16aS, 16bR)-2-(6-deoxy-2, 3, 4-
tri-O-methyl-R-L-mannopyranosyloxy)-13-(4-dimethylamino-2, 3,
4, 6-tetradeoxy-b-D-erythropyranosyloxy)-9-ethyl-2, 3, 3a, 5a, 6,
7, 9, 10, 11, 12, 13, 14, 15, 16a, 16b-hexadecahydro-14methyl-1H-
8-oxacyclododeca[b]as-indacene-7,15-dione
Spinosyn D :- (2R, 3aS, 5aR, 5bS, 9S, 13S, 14R, 16aS, 16bR)-2-(6-deoxy-2, 3, 4-
tri-O-methyl-R-L-mannopyranosyloxy)-13-(4-dimethylamino- 2,
3, 4, 6-tetradeoxy-b-D-erythropyranosyloxy)-9-ethyl-2, 3,3a, 5a, 6,
7, 9, 10, 11, 12, 13, 14, 15, 16a,16b-hexadecahydro-4, 14-
dimethyl-1H-8 oxacyclododeca[b]as-indacene-7, 15-dione
Chemical formula :- C41H65NO10 (A)
C42H67NO10 (D)
Chemical structure:
25
Key character: it is an insecticide based on chemical compounds found in the
bacterial species Saccharopolyspora spinosa. The genus Saccharopolyspora was
discovered in 1985 in isolates from crushed sugarcane which produce yellowish pink
Aerial hyphae, with beadlike chains of spores enclosed in a characteristic hairy
sheath. Spinosad contains a mix of two spinosoids, spinosyn A, the major component,
and spinosyn D (the minor component), in a roughly 17:3 ratio.
Mode of action: Spinosad is highly active, by both contact and ingestion, in
numerous insect species. The mode of action of Spinosad insecticides is by a neural
mechanism. The spinosyns and spinosoids have a novel mode of action, primarily
targeting binding sites on nicotinic acetylcholine receptors (nAChRs) of the insect
nervous system that are distinct from those at which other insecticides have their
activity. Spinosad binding leads to disruption of acetylcholine neurotransmission.
Spinosad also has secondary effects as a gamaaminobutyric acid (GABA)
neurotransmitter agonist. It kills insects by hyper excitation of the insect nervous
system.
Triazophos 35%EC
Chemical name :- Triazophos
Trade name :- Subhathion
Source :- Tata Chemicals Pvt. Ltd
IUPAC Name :- diethoxy [(1phenyl1, 2,4triazol3yl) oxy] sulfanylidene$
l^ {5}phosphane
Chemical formula :- C12H16N3O3PS
Chemical structure:
26
Key character: its molecular formula is C12H16N3O3PS. And its molecular
weight is 313.312502 g/mol. It looks like Yellowish oil, Used to control insects,
mites, and nematodes.
Mode of action: Triazophos is an organophosphate insecticide and belongs to
Acetyl cholinesterase (AChE) inhibitors. Triazophos is a broad-spectrum insecticide
and acaricidal with contact and stomach action. It is non systemic, but penetrates
deeply into plant tissues.
Thiomethoxam 25%WG
Chemical name :- Thiomethoxam
Trade name :- Tksthia
Source :- Tata Chemicals Pvt. Ltd
IUPAC Name :- 3[(2Chloro1, 3thiazol5yl) methyl] 5methylNnitro1,
3,5oxadiazinan4imine
Chemical formula :- C8H10ClN5O3S
Chemical structure:
Key character: Thiomethoxam is a systemic insecticide in the class of
neonicotinoids. It has a broad spectrum of activity against many types of insects. Its
molecular weight is 291.71 g·mol−1 , density is 1.57 g/cm3 , and solubility in water is
4.1 g/L.
Mode of action: Thiomethoxam is a broad-spectrum, systemic insecticide,
which means it is absorbed quickly by plants and transported to all of its parts,
including pollen, where it acts to deter insect feeding. An insect can absorb it in its
27
stomach after feeding, or through direct contact, including through its tracheal system.
The compound gets in the way of information transfer between nerve cells by
interfering with nicotinic acetylcholine receptors in the central nervous system, and
eventually paralyzes the muscles of the insects.
Profenophos 50%EC
Chemical name :- Profenophos
Trade name :- Carina
Source :- Pesticides India Ltd.
IUPAC Name :- O-4-bromo-2-dichlorophenyl O-ethyl S-propyl
phosphorothioate
Chemical formula :- C11H15BrClO3PS
Chemical structure:
Key character: The technical Profenophos is a pale yellow liquid. It is
miscible with most organic solvent and water solubility at 200 C is 20 mg/l of water.
Its molecular formula is C11H15BrClO3PS having molecular weight of 373.6 g/ml.
Mode of action: non- systemic with contact and stomach action. Acetyl
cholinesterase (AchE) inhibitor.
28
Imidacloprid 17.8%SL
Chemical name :- Imidacloprid
Trade name :- Imigrow
Source :- Crop Life Sciences Ltd.
IUPAC Name :- N{1[(6Chloro3pyridyl)methyl]4,5dihydroimidazol2yl}
nitramide
Chemical formula :- C9H10ClN5O2
Chemical structure:
Key character: The technical imidacloprid is a colourless crystals form. Its
molecular weight is 255.661 g/ml. And water solubility at 200C is 0.51g/l of water.
Mode of action: it is a systemic insecticide which acts as an insect neurotoxin
and belongs to a class of chemicals called the neonicotinoids which act on the central
nervous system of insects; it causes a blockage of the nicotinergic neuronal pathway.
By blocking nicotinic acetylcholine receptors, Imidacloprid prevents acetylcholine
from transmitting impulses between nerves, resulting in the insect's paralysis and
eventual death. It is effective on contact and via stomach action.
Fipronil 5%SC
Chemical name :- Fipronil
Trade name :- Regent
Source :- Bayer Crop Science
IUPAC Name :- (RS)-5-Amino-1-[2,6-dichloro-4-
(trifluoromethyl)phenyl]-4
(trifluoromethylsulfinyl)pyrazole-3-carbonitrile
Chemical formula :- C9H10ClN5O2
29
Chemical structure:
Key character: Fipronil is a broad-use insecticide that belongs to
the phenylpyrazole chemical family. Its molecular weight is 437.14 g·mol−1
Mode of action: Fipronil is a broad spectrum insecticide that disrupts the insect
central nervous system by blocking GABA gated chloride channels and glutamate
gated chloride (GluCl) channels, resulting in central nervous system toxicity. It blocks
the gamma amino butyric acid (GABA) regulated chloride channels, neurons, thus
antagonizing the calming effect of GABA.
Dimethoate 30% (EC) (Standard check)
Chemical name :- Dimethoate
Trade name :- Rogar
Source :- Cheminova India Ltd.
IUPAC Name :- O, Odimethyl S [2(methylamino) 2oxoethyl]
dithiophosphate
Chemical formula :- C5H12NO3PS2
Chemical structure:
30
Key character: its molecular weight is 229.26 g/mol. The pure crystals are
colourless solid crystal having camphor like odour. Its vapour pressure is 8.5x 10-6
mm Hg and its water solubility is 25 g/l.
Mode of action: it is an anticholinesterage which disables cholinesterase, an
enzyme essential for central nervous system function. It is systemic insecticides
widely used against sucking insect pest on various crops.
Neem oil:
Trade name: Bioneem
Source: Crop Life Sciences Ltd.
It is neem based products or pesticides, which is used in plant protection.
Neem oil is key products of neem. The kernels of neem seed are rich in oil, yielding
about 40to 50% of oil with a bitter taste and disagreeable odour. The oil has high
tocopherol content 1.17mg/gms made up of gamma and delta forms. The oil has
greenish brown colour having repulsive garlic odour. Neem oil also yields a number
of alkaloids and lipid associates such as Nimbidol, Nimbidin, Nimbin, Nimbinin,
Vepanin, Pyronimin etc.
Neem oil is used in the treatment of several diseases and pests. It has
insecticidal and insect hormonal properties. The medicinal and insecticidal properties
are due to the presence of certain organic compounds belonging to the group
Limonoids.
Mode of action: Neem based active ingredients exhibited various effects such as
ovoposition deterrent, ovicidal, antifeedent, repellent, growth inhibitant, insecticidal,
antifungal, antibacterial, antiviral, acaricidal and nematicidal.
Yam bean seed extract (YBSE):
Yam bean is a leguminous crop. The flowers are violet and born on fascicled
pedicels in recemes. The mature seeds have high content of alkaloids and insecticidal
properties. Mature seeds of yam bean contain a toxic compound called rotenone
(C23H22O6 ) which is contact and fumigant in action.
31
After harvesting, plot wise seed yield was recorded and converted into tonnes
per ha. The per cent increase in yield over untreated control was also calculated for
assessing the yield performance of different treatments by using following formula:
Whereas,
Y1= seed yield in untreated control
Y2....Y9= seed yield in different treatments.
Mean (%) decrease in thrips population over untreated control:
Whereas,
P1= thrips population in untreated control
P2....P9= thrips population in treated control
Overall efficacy was compared on the basis of net monitory returns in term of
rupees per hectare as well as benefit-cost ratio worked out for different treatments
under study. Data so obtained were subjected to statistical analysis.
The marginal benefit cost ratio (MBCR) was calculated on the basis of
prevailing market price of mungbean, insecticides and spraying cost. Marginal benefit
cost ratio was calculated as follows:
MBCR =
100
Y2....Y9-Y1
Y1 100
P1 – P2......P9
P1 100
32
RESULTS AND DISCUSSION
With a view to determine the seasonal abundance and to explore the
possibility of management of thrips, Megalurothrips distalis Karny on mungbean a
series of field experiments were conducted during 2015-16, at research farm, T.C.A
Dholi, Muzaffarapur, Bihar. The experimental findings pertaining to the various
aspects of present studies are presented and discussed as under:
4.1 Population dynamics of thrips, Megalurothrips distalis Karny on mungbean
The data pertaining to the mean number of thrips per plant have been
summarized in Table 1 and illustrated in fig. 1. The data presented in the table clearly
revealed that the pest activity was initially observed in 17th standard week of April,
2015 and continued till the pod maturity stage of the crop (24th standard week of June,
2015). It could be further inferred that the pest population in the beginning was low
(1.2 thrips/leaf) which increased and reached (4.4 thrips/leaf) in the 18th standard
week of May, 2015. Its population started declining slowly (2.4, 2.2 and1.4 thrips/
leaf) after 19th standard week of May to 21st standard week of May, 2015. It might be
due to decreasing in temperature, unexpected rainfall (25.8, 6.8 and 6.0 mm) noticed
during these standard weeks continuously, but again thrips population suddenly
increased and reached its peak (5.6 thrips/ leaf) was observed on 22nd standard week
of June, 2015.
So far as the effect of weather parameters is concerned, the maximum number
of thrips population (5.6 thrips/ leaf) was recorded during 22nd standard week of June,
2015 when corresponding weather parameters viz; maximum, minimum temperature
(oC), relative humidity (%) at 07 and 14 hrs and rainfall (mm) were 40.5, 27.5, 87.7,
46.7 and nil, respectively. On the other hand minimum population of thrips (1.0
thrips/ leaf) was recorded to be 35.00C, 25.30C, 93.8%, 68.7% and 18.6mm,
maximum and minimum temperature, relative humidity at 7 AM and 2 PM and
rainfall, respectively.
The data pertaining to the mean number of thrips per flower was also
recorded and summarized in Table 1 and illustrated in fig. 1. The data presented in the
table clearly revealed that the pest activity was initially observed on flower in 18th
4
Table 1. Population build up of thrips, Megalurothrips distalis Karny on mungbean cv. SML668 in relation to weather parameters during summer season 2015-16.
Months Standard week
Mean no. of thrips/plant
Mean no. of thrips/flower
Mean temperature (oC) R.H (%) Rainfall (mm)
Max. Min. 7 hrs 14 hrs
April 17 1.2 - 34.1 21.0 89.2 65.7 -
May 18 4.4 6.6 34.5 21.3 89.5 66.1 -
19 2.4 4.6 34.0 23.7 90.1 66.5 25.8
20 2.2 3.2 35.4 24.4 91.8 64.1 6.8
21 1.4 - 37.6 24.5 92.4 61.2 6.0
June 22 5.6 - 40.5 27.5 87.7 46.7 -
23 3.0 - 37.6 26.2 92.4 57.7 -
24 1.0 - 35.0 25.3 93.8 68.7 18.6
Fig. 1. Population build up of thrips, Megalurothrips distalis Karny on mung bean cv. SML668 in relation to weather parameters during summer season 2015-16.
0
1
2
3
4
5
6
7
0
10
20
30
40
50
60
70
80
90
100
17 18 19 20 21 22 23 24
standard week
Mean no. of thrips/plant Mean no. of thrips/flower Max. Temp. Min. Temp.
R.H (%) 7 hrs R.H (%) 14 hrs Rain fall (mm)
wea
ther
par
amet
ers
standard week of May, 2015 and continued till the pod maturity stage of the crop (20th
standard week of May, 2015). It could be further inferred that the pest population in
the beginning was high (6.6 thrips/ flower) which gradually decreased and reached
(4.6 thrips/ flower) in the 19th standard week of May, 2015. Its population started
declining slowly (3.2 thrips/ flower) after 20th standard week of May, 2015 when pod
formation stage. The maximum population (6.6 thrips/ flower) was observed on 18th
standard week of May, 2015 when the corresponding weather parameters viz;
maximum, minimum temperature (oC), relative humidity(%) at 07 and 14 hrs and
rainfall (mm) were 34.50C, 21.30C, 89.5%, 66.1% and nil, respectively. On the other
hand minimum population of thrips (3.2 thrips/ flower) was recorded to be 35.40C,
24.40C, 91.8%, 64.1% and 6.8 mm, respectively of the above weather parameters.
From the foregoing experimental findings, it was quite clear that the thrips
population per plant was increased (4.4 thrips/plant) after 18th standard week of May,
2015, and decreased suddenly due to occurring of rainfall in 19th standard week to 21st
standard week of May, 2015 when the temperature is increased its peak again the
thrips population increased during the 22nd standard week of June, 2015 (5.6
thrips/plant). The thrips population per flower was high (6.6 thrips/flower) on 18th
standard week of May, 2015, the sudden drop of thrips population on flower is may
be due to unexpected rainfall and also ending of flowering stage of the crop. Gupta
and Singh (1993) reported that thrips population was high up to vegetative growth and
attained peak period by 2nd week of May. They also reported that the thrips population
was low in rainy season than the summer season. This clearly indicated that the
preference of dry conditions by thrips. Duraimurugan and Tyagi (2014) reported that
during summer season mungbean, the thrips population in leaf ranged from 4.2 to
19.0 at 20th and 24th standard meteorological week (SMW) per five plants in
mungbean. As flowering initiated, flower thrips incidence occurred and it remained
active till pod maturation. The population ranged from 17.0 to 57.2 at 20th to 22nd
SMW and the population of thrips reached its peak at 22nd SMW in mungbean. The
results obtained in present investigation are in agreement with the reports of above
mentioned workers.
34
Table 2. Correlation coefficient and regression equation between weather parameters (X) and mean number of thrips per plant (Y2).
Weather parameters Correlation coefficient (r)
Maximum Temperature (0C) (X1) 0.628*
Minimum Temperature (0C) (X2) 0.339
R.H. 7 hrs. (%) (X3) -0.579*
R.H. 14 hrs. (%) (X4) -0.769**
Rainfall (mm) (X5) -0.599*
Multiple regression equation: Y2 = 28.573 + 0.257 (X1) + 0.542 (X2) –0.643 (X3) +0.174 (X4) –0.096 (X5) Coefficient of determination (R2) = 0.719* *Significant at P = 0.05 and **Significant at P = 0.01
4.1.2 Correlation coefficient
The correlation analysis between weather parameters and the population of
mungbean thrips have been summarized in Table 2. The data, presented in the table
clearly revealed that maximum temperature and minimum temperature showed highly
positive association with thrips population (r= 0.628 and 0.339). The relative
humidity recorded at 7 hrs and 14 hrs showed highly significant negative effect on
thrips population (r= -0.576 and -0.769). However, the rainfall recorded during the
crop period was very high i.e. 25.8 mm. Therefore, their effect was too much
pronounced and showed significant negative effect on thrips population (r= -0.599).
However all the weather parameters together govern 71.9 percent towards thrips
population when acted together (R2 = 0.719). The interactions between thrips
population and prevailing weather parameters as obtained in present investigation
provided a good support to the earlier findings of Gupta and Singh (1993) and
Duraimurugan and Tyagi (2014).
4.2 Effects of dates of sowing on the incidence of thrips on green gram.
Result of field trial that was carried out in summer season of 2015-16 to
explore possibility of managing thrips, Megalurothrips distalis Karny infestation on
mungbean (cv. SML 668) through manipulation in sowing date is presented and
discussed below:
4.2.1 Mean number of thrips per plant on mungbean (cv. SML 668) as influenced
by dates of sowing
The data on mean number of thrips per plant, as summarized in Table 3 and
illustrated in Fig. 2 revealed a mark variation among different date of sowing the
mean number of thrips per plant recorded on increasing trend with delay in sowing.
Among the different dates of sowing significantly lowest population of thrips (1.0,
2.1, 2.9, 4.1, 3.6, 1.8 and 1.3 thrips/plant) was recorded on mungbean crop sown on
1st April, 2015 at 4th, 5th, 6th, 7th, 8th, 9th and 10th weeks after sowing (WAS),
respectively, with lowest cumulative mean number of thrips 2.4 per plant. The pest
population in the crop sown on 24th March was considered to be the next best date of
sowing in term of recording lower level of thrips population varied from 1.2 to 5.5 per
35
Table 3. Effects of date of sowing on the population of thrips, Megalurothrips distalis Karny on mungbean cv. SML668 during summer season 2015-16.
Treatments (Date of sowing)
Mean no. of thrips per plant at Cumulative mean no. of thrips/plant 4WAS* 5WAS 6WAS 7WAS 8WAS 9WAS 10WAS
D1 (24-03-2015) 1.2 (1.48)**
2.3 (1.80)
2.6 (1.89)
5.5 (2.55)
3.8 (2.17)
2.5 (1.87)
1.7 (1.64)
2.8 (1.93)
D2 (01-04-2015) 1.0 (1.41)
2.1 (1.75)
2.9 (1.96)
4.1 (2.25)
3.6 (2.14)
1.8 (1.67)
1.3 (1.51)
2.4 (1.82)
D3 (11-04-2015) 1.9 (1.69)
2.8 (1.93)
3.7 (2.17)
5.8 (2.60)
4.2 (2.28)
3.3 (2.16)
2.1 (1.75)
3.4 (2.06)
D4 (20-04-2015) 3.8 (2.17)
4.7 (2.38)
7.6 (2.93)
11.3 (3.51)
8.3 (3.04)
4.6 (2.38)
3.1 (2.02)
6.2 (2.65)
D5 (29-04-2015) 2.4 (1.83)
3.7 (2.16)
6.1 (2.66)
9.4 (3.22)
4.5 (2.34)
3.8 (2.17)
2.3 (1.81)
4.6 (2.35)
SEm(±) CD (P=0.05)
(0.10) (0.30)
(0.08) (0.25)
(0.12) (0.36)
(0.07) (0.23)
(0.09) (0.27)
(0.13) (0.39)
(0.09) (0.28)
(0.09) (0.29)
*Weeks after sowing. **Figures in parentheses are values of square root transformations
plant with lower cumulative mean number of thrips (2.8/plant) which was at par with
the thrips population recorded on mungbean crop sown on 1st April, 2015. Highest
population of thrips (3.8, 4.7, 7.6, 11.3, 8.3, 4.6 and 3.1/ plant) with cumulative mean
of 6.2 thrips per plant was recorded when crop was sown on 20th April, 2015. Among
remaining two dates of sowing the lower cumulative mean number of thrips (3.4 and
4.6 thrips/plant) was recorded when crop sown on 11th and 29th April, 2015
respectively, and found significantly superior as compared to the crop sown on 20th
April 2015, but significantly inferior as compared to the crop sown on 1st April, 2015
and 24th March 2015, in respect of thrips population.
On the basis of findings presented above it can be concluded that the
mungbean crop sown up to 1st week of April was found to suffer least due to lower
level of thrips population ranging from 2.8 to 2.4 thrips per plant. Delaying in its
sowing afterwards carry higher population of thrips (3.4- 6.2 thrips/plant). Lower
population of thrips up to 1st week of April might be due to low temperature and high
humidity during the vegetative stage of the crop. These two abiotic factors are not
congenial for rapid growth and development of thrips as well as the vegetative stage
of the crop do not synchronise with higher population of thrips. It has also been
observed that the crop sown on 20th April 2015 harbour maximum number of thrips
per plant (6.2 thrips/plant) which might be due to increase in temperature and dry
weather prevailing during the vegetative stage of the crop. The present findings got
good support from the earlier reports of several workers viz: Sehgal and Ujagir (1988)
and Hossain et al. (2009).
On the basis of the experimental findings discussed above, it could be
generalized that the sowing of mungbean crop up to 1st April suffered least and
recorded lower number of thrips, but delaying in the sowing of crop up to 29th April
the problem of thrips population may be more at vegetative stage of the crop.
4.2.2 Mean number of thrips per flower on mungbean (cv. SML 668) as
influenced by dates of sowing
The data presented in Table 4 and illustrated in Fig. 2 clearly revealed that the
mean number of thrips per flower varied significantly as influenced by different date
of sowing.
36
Table 4. Effects of date of sowing on the population of thrips, Megalurothrips distalis Karny per flower of mungbean cv. SML668 during summer season 2015-16.
Treatments
(Date of sowing)
Mean no. of thrips per flower Cumulative no. of thrips
per flower 6WAS* 7WAS
D1 (24-03-2015) 1.2
(1.47)**
2.2
(1.78)
1.7
(1.62)
D2 (01-04-2015) 1.0
(1.40)
1.6
(1.61)
1.3
(1.44)
D3 (11-04-2015) 3.2
(2.04)
5.0
(2.46)
4.1
(2.23)
D4 (20-04-2015) 4.0
(2.23)
5.8
(2.60)
4.9
(2.14)
D5 (29-04-2015) 2.9
(1.96)
4.5
(2.34)
3.7
(2.31)
SEm(±)
CD (P=0.05)
(0.08)
(0.26)
(0.07)
(0.23)
(0.10)
(0.31)
*Weeks after sowing. **Figures in parentheses are values of square root transformations
The lowest thrips population (1.0 and 1.6 thrips/flower) was recorded when
crop sown on 1st April 2015 with cumulative mean number of thrips per flower (1.3
thrips/flower) which was found to be statistically at par when sowing was done on
24th March 2015 with mean number of thrips 1.2 and 2.2 per flower at 6 and 7 weeks
after sowing (WAS), with cumulative mean number of thrips per flower was 1.7.
Among the different date of sowing the highest thrips per flower was recorded to be
4.0 and 5.8 with cumulative mean number of thrips 4.9 per flower, when crop was
sown on 20th April 2015. However, there was no significantly difference in respect of
mean number thrips per flower when sowing was done on 11th and 29th April 2015
with the crop sown on 20th April 2015.
On the basis of findings presented above it can be concluded that the
mungbean crop sown after 11th April onwards suffered most due to thrips attack and
the most favourable time for sowing of mungbean starts from last week of March to
first week of April having lower number of thrips per flower (1.7 and 1.3 thrips/
flower, respectively).
The lowest thrips population might be due to synchrony with higher
population of thrips with most vulnerable stage that is flower. The present findings
also got good support from the reports of Hossain et al. (2009).
Hence, the experimental findings discussed above, it could be concluded that
the sowing of mungbean crop up to 1st week of April harbour least number of thrips
per flower and by delaying the sowing of this crop the problem of thrips population
may be increased on flower.
4.2.3 Extent of pod infestation due to thrips, Megalurothrips distalis Karny on
mungbean cv. SML 668 as influenced by dates of sowing
The data recorded on effect of sowing date on mean number of pods per plant,
mean number of deformed pods per plant and per cent pod infestation caused by
thrips, Megalurothrips distalis Karny during the period under investigation are given
in Table 5. Perusal of data as influenced by date of sowing clearly revealed that mean
number of pods varied significantly from 47.37 to 41.45 per plant with maximum and
minimum being recorded on the crop sown on 1st April and 29th April 2015,
37
Table 5. Effects of date of sowing on per cent pod infestation caused by thrips, Megalurothrips distalis Karny on mungbean cv. SML668 during summer season 2015-16.
Treatments (Date of sowing)
Mean no. of pods/plant
Mean no. of deformed pods/plant
Pod infestation (%)
D1 (24-03-2015) 42.35 8.30 19.59
D2 (01-04-2015) 47.37 5.35 11.17
D3 (11-04-2015) 44.30 10.47 24.63
D4 (20-04-2015) 45.27 12.35 27.28
D5 (29-04-2015) 41.45 8.42 20.31
SEm (±)
CD (P=0.05)
1.37
4.10
0.52
1.63
1.64
5.11
respectively. Remaining treatments occupied intermediate positions between 42.35 to
45.27 per plant when crop sown on 24th March and 20th April 2015, respectively.
The effect of sowing dates on deformed pods caused by thrips was highly
pronounced (Table 5). Among different date of sowing significantly highest number
of deformed pods (12.35/plant) was recorded when mungbean crop sown on 20th
April, 2015 while, lowest (5.35/plant) was recorded when crop sown on 1st April
2015. Remaining treatments occupied intermediate positions between them.
As it is obtained from the data presented in Table 5 revealed that the mean
percent pod infestation varied significantly from 11.17 to 27.28 percent with
minimum and maximum being recorded with the crop sown on 1st April and 20th
April 2015. Among remaining treatments lower pod infestation (19.59%) was
recorded when crop sown on 24th March 2015, which was statistically at par with the
crop sown on 29th April 2015 (20.31%).
On the basis of present findings discussed above, 1st April proved to be the
most suitable date of sowing in respect more number of pods per plant (47.37/plant),
lowest number of deformed pods (5.35/plant) and lowest mean percent pod infestation
(11.17%). Among all dates of sowing in mungbean followed by crop sown on 24th
March 2015. No works seems to have been done earlier for the effect of sowing date
on mean percent pod infestation due to thrips in mungbean under field condition. The
present findings therefore seem to have a new contribution to this field.
4.2.4 Effect of date of sowing on grain yield of mungbean cv. SML 668 under
unprotected condition
As in case the test weight of 100 seeds in mungbean was significantly
influenced by various date of sowing during the crop season (Table 6). The average
weight of 100 seeds in various treatments ranged from 2.7 to 4.6 gm with minimum
and maximum being recorded when crop sown on 20th April and 1st April 2015.
Remaining treatments occupied intermediate positions between them.
The effect of different date of sowing was finally judged on the basis of grain
yield which showed a wide variation during the crop season. The data presented in
Table 6 and illustrated in Fig 2 clearly revealed that the mean grain yield varied
38
Table 6. Effects of date of sowing on grain yield of mungbean cv. SML668 during summer season 2015-16.
Treatments (Date of sowing)
Test weight of 100 seed (g)
Grain yield (q/ha)
Per cent decrease in yield over 2nd date of sowing
D1 (24-03-2015) 3.8 11.4 21.91
D2 (01-04-2015) 4.6 14.6 -
D3 (11-04-2015) 3.1 9.6 34.24
D4 (20-04-2015) 2.7 8.5 41.78
D5 (29-04-2015) 2.9 8.7 40.41
SEm (±)
CD (P=0.05)
0.22
0.69
0.49
1.51
-
-
Fig. 2. Effects of dates of sowing on thrips population and grain yield (q/ha) in mungbean during 2015-16.
0
2
4
6
8
10
12
14
16
D1 (24-03-2015) D2 (01-04-2015) D3 (11-04-2015) D4 (20-04-2015) D5 (29-04-2015)
Mea
n no
of t
hrip
s per
pla
nt, f
low
er a
nd g
rain
yie
ld (q
/ha)
Treatments
Cumilative mean no. of thrips/plant Cumilative mean no. of thrips/flower grain yield
widely from 8.5 to 14.6 q/ha with minimum and maximum being recorded when
sowing was done on 20th April 2015 and 1st April 2015. Among the remaining
treatments better yield (11.4 q/ha) was recorded when the crop sown on 24th March,
2015 and occupied second position. Delay in sowing after 1st April brought about
progressive decrease in grain yield varied from 9.6 to 8.7 q/ha. Amount of reduction
in yield over 2nd date of sowing varied considerably from one date of sowing to
another. It was the lowest (21.91%) and the highest (41.78%) when the crop sown on
24th March, 2015 and 20th April 2015, respectively.
From the foregoing experimental findings, it becomes quite clear that the test
weight and grain yield were adversely affected due to thrips attack under different
date of sowing. The present findings were strongly supported by reports of Hossain et
al. (2009) and Sreekanth et al. (2002).
4.3 Relative efficacy of synthetic insecticides and plant products against thrips,
Megalurothrips distalis Karny on mungbean cv. SML 668
In order to ascertain the field efficacy of synthetic insecticides and some plant
products in combating thrips population/infestation on mungbean (cv. SML 668) , a
field experiment comprising spinosad, triazophos, thiomethoxam, profenophos,
imidacloprid, fipronil, neem oil, yam bean seed extract (YBSE), dimethoate and
untreated control was conducted during 2015. The formulations, application and
concentration used have already been given in materials and methods. The results of
the present investigations were presented here along with relevant discussion.
4.3.1 Effect of synthetic insecticides and plant products on thrips, Megalurothrips
distalis Karny on mungbean cv. SML 668
The data on mean number of thrips per plant recorded one day prior to
spraying of all the test products and at 1st, 5th and 10th days after each spraying. The
relevant data presented in Table 7, clearly revealed that the thrips population recorded
before one day prior to commencement of spray schedule showed non significant
differences among various treatments varied from 3.0 to 3.4 thrips per plant indicating
homogenous distribution of thrips population in experimental plot. However, there
were significant differences between the treatments after each of the two sprays in
respect of thrips population. The mean number of thrips per plant on mungbean
39
Table 7. Relative efficacy of synthetic insecticides and plant products (after 1st spraying) against thrips, Megalurothrips distalis Karny on mung bean cv. SML668 during summer season 2015-16.
Treatments
Mean no. of thrips/plant after 1st spraying
Mean
Mean % reduction in thrips
population over control/dimethoate
Before one day of 1st spraying
1 DAS** 5DAS 10DAS
T1-Spinosad (45 SC) @ 0.045% 3.0 (1.00)*
3.1 (2.01)
3.2 (2.04)
3.9 (2.21)
3.4 (2.09)
15.00 (-41.66)***
T2- Triazophos ( 35 EC) @ 0.04% 3.2 (1.59)
2.6 (1.89)
2.6 (1.89)
3.2 (2.04)
2.8 (1.94)
30.02 (-16.66)
T3-Thiomethoxam (25WG) @ 0.025% 3.2 (1.59)
2.2 (1.78)
2.4 (1.83)
2.9 (1.97)
2.5 (1.87)
37.50 (-4.16)
T4- Profenophos (50 EC) @ 0.05% 3.0 (1.74)
2.4 (1.83)
2.4 (1.83)
3.0 (1.99)
2.6 (1.89)
35.50 (-8.33)
T5-Imidacloprid (17.8 SL)@ 0.005% 3.2 (1.59)
1.4 (1.54)
1.6 (1.60)
2.0 (1.74)
1.6 (1.60)
60.00 (33.33)
T6- Fipronil (5 SC) @ 0.05% 3.4 (1.60)
2.8 (1.94)
2.8 (1.94)
3.4 (2.09)
3.0 (1.99)
25.00 (-25.00)
T7- Neem oil @3% 3.4 (1.71)
3.3 (2.07)
3.4 (2.09)
4.0 (2.23)
3.5 (2.11)
12.50 (-45.83)
T8- YBSE @5%
3.0 (1.06)
2.9 (1.97)
3.0 (1.99)
3.8 (2.18)
3.2 (2.04)
20.00 (-33.33)
T9- Dimethoate (30EC )@ 0.03% 3.2 (1.79)
2.2 (1.78)
2.2 (1.78)
2.8 (1.99)
2.4 (1.83) 40.00
T10- Control
3.4 (1.61)
3.6 (2.14)
4.0 (2.23)
4.4 (2.32)
4.0 (2.23)
- (-66.66)
SEm (±) CD (P=0.05)
- NS
(0.09) (0.28)
(0.09) (0.27)
(0.08) (0.25
(0.09) (0.29)
*Figures in parenthesis are the values of square root transformations; **DAS = Days after spraying ***Percent reduction in thrips over dimethoat
ranged between 1.4 to 3.6, 1.6 to 4.0 and 2.0 to 4.4 per plant at 1st, 5th and 10th days
after 1st spraying with minimum and maximum population being recorded in
imidacloprid 17.8 SL (@0.005%) and untreated control, respectively. Among the
remaining treatments, thiomethoxam 25 WG (@ 0.025%) and dimethoate 30 EC (@
0.03%) showed better performance in suppressing thrips population (2.2 thrips per
plant each at one day after 1st spraying) with no statistical difference among them
andwer found at par with imidacloprid 17.8 SL (@0.005%) at their test doses
followed by profenophos 50 EC (@ 0.05%) with mean number of 2.4 thrips per plant.
Among the plant products neem oil (3%) and yam bean seed extract (5%) showed
poor performance in suppressing thrips (3.3 and 2.9 thrips/plant, respectively) and
found statistically at par with control (3.6 thrips/plant) at one day after 1st spraying. At
5th day after 1st spraying lowest thrips population (1.6/plant) was recorded in
imidacloprid 17.8 SL (@0.005%) which was statistically at par with dimethoate 30
EC (@ 0.03%) (2.2 thrips/plant), thiomethoxam 25 WG (@ 0.025%) (2.4
thrips/plant), profenophos 50 EC (@ 0.05%) (2.4 thrips/plant) and triazophos 35 EC
(@ 0.04%) (2.6 thrips/plant) after 1st spraying as against 4.0 thrips per plant in
untreated control. Foliar spray of imidacloprid 17.8 SL (@0.005%) was found to
continue significantly superior in suppressing thrips population (2.4 thrips/plant) at
10th day after 1st spraying as against 4.4 thrips per plant in untreated control. Among
the remaining treatments dimethoate 30 EC (@ 0.03%), thiomethoxam 25 WG (@
0.025%), profenophos 50 EC (@ 0.05%) and triazophos 35 EC (@ 0.04%) showed
better performance in recording lower number of thrips 2.8, 2.9, 3.0 and 3.2 per plant,
respectively which statistically at par with imidacloprid 17.8 SL (@0.005%) but
significantly superior over untreated control. All the plant products under test where
found least effective in comparison to rest of the chemical insecticides with no
statistically difference from untreated control at 10th day after 1st spraying.
On the basis of mean population of thrips at after 1st spraying, the relevant
data presented in (Table 7) clearly indicated that the lowest population (1.6
thrips/plant) and maximum reduction in thrips population (60.00%) over untreated
control was recorded with imidacloprid 17.8 SL (@0.005%) which was statistically at
par with dimethoate 30 EC (@ 0.03%) (2.4 thrips/plant), thiomethoxam 25 WG (@
0.025%) (2.5 thrips/plant), profenophos 50 EC (@ 0.05%) (2.6 thrips/plant) and
40
triazophos 35 EC (@ 0.04%) (2.8 thrips/plant) with mean percent reduction over
untreated control was 40.00, 37.50, 35.50 and 30.02 percent, respectively. The data
related to mean per cent reduction in thrips population over dimethoate (Table 7)
clearly revealed that except imidacloprid none of the treatments showed its supremacy
better than dimethoate. However, maximum reduction in thrips (33.33%) was
recorded with imidacloprid 17.8 SL (@ 0.005%) over dimethoate.
All the treatments under test were found significantly superior over untreated
control in suppressing thrips population at 1st, 5th and 10th days after 2nd spray. The
data presented in Table 8 clearly revealed that the thrips population varied from 1.2 to
4.6, 1.8 to 5.2 and 2.4 to 6.2 per plant with minimum and maximum being in
imidacloprid 17.8 SL @0.005% and untreated control at 1st , 5th and 10th days after 2nd
spraying, respectively. Among the remaining treatments, thiomethoxam 25 WG (@
0.025%), profenophos 50 EC (@ 0.05%), triazophos 35 EC (@ 0.04%) and
dimethoate 30 EC (@ 0.03%) showed better performance in suppressing thrips
population (1.4, 1.6, 1.8 and 1.4 thrips/ plant, respectively) with no significant
difference among themselves and imidacloprid 17.8 SL applied @0.005%. At 5th and
10th days after 2nd spraying imidacloprid 17.8 SL (@0.005%) continued to perform
better in minimizing thrips population (1.8 and 2.4 thrips/plant, respectively) which
was at par with thiomethoxam 25 WG (@ 0.025%) (2.3 and 2.9 thrips/plant),
profenophos 50 EC (@ 0.05%) (2.4 and 3.0 thrips/plant) and dimethoate 30 EC (@
0.03%) (2.2 and 2.7 thrips/plant) as against 5.2 and 6.2 thrips per plant in untreated
control at 5th and 10th days after 2nd spraying. Among the plant products neem oil and
yam been seed extract continue to showed poor performance as compared to the
synthetic insecticides but significantly superior over untreated control in respect to
suppressing thrips population varied from 2.6 to 4.2 and 2.4 to 3.8 thrips per plant,
respectively.
The data on cumulative mean of thrips population recorded at 1st, 5th and 10th
days after 2nd spraying clearly revealed that all the treatments were found significantly
superior in minimizing thrips population over control (Table 8). Among the remaining
treatments under test, foliar application of imidacloprid 17.8 SL @0.005% proved to
be most effective in minimizing thrips population (1.8 thrips/plant) which was on par
with dimethoate (2.1 thrips/plant), thiomethoxam (2.2 thrips/plant) and profenophos
41
Table 8. Relative efficacy of synthetic insecticides and plant products (after 2nd spraying) against thrips, Megalurothrips distalis Karny on mung bean cv. SML668 during summer season 2015-16.
Treatments
Mean no. of thrips/plant after 2nd spraying Mean
Mean % reduction in thrips population over
control/dimethoate 1 DAS** 5DAS 10DAS
T1-Spinosad (45 SC) @ 0.045% 2.5 (1.86)*
3.5 (2.11)
3.9 (2.21)
3.3 (2.07)
37.73 (-57.14)***
T2- Triazophos ( 35 EC) @ 0.04% 1.8 (1.66)
2.7 (1.91)
3.4 (2.09)
2.6 (1.89)
50.94 (-23.80)
T3-Thiomethoxam (25WG) @ 0.025% 1.4 (1.54)
2.3 (1.81)
2.9 (1.97)
2.2 (1.78)
58.49 (-4.76)
T4- Profenophos (50 EC) @ 0.05% 1.6 (1.60)
2.4 (1.84)
3.0 (1.99)
2.3 (1.81)
54.71 (-9.52)
T5-Imidacloprid (17.8 SL)@ 0.005% 1.2 (1.47)
1.8 (1.66)
2.4 (1.84)
1.8 (1.66)
66.03 (14.28)
T6- Fipronil (5 SC) @ 0.05% 2.2 (1.78)
2.9 (1.97)
3.6 (2.14)
2.9 (1.97)
45.28 (-38.09)
T7- Neem oil @3% 2.6 (1.89)
3.8 (2.19)
4.2 (2.27)
3.5 (2.11)
33.96 (-66.66)
T8- YBSE @5% 2.4 (1.83)
3.2 (2.04)
3.8 (2.18)
3.1 (2.01)
41.50 (-47.61)
T9- Dimethoate (30EC )@ 0.03% 1.4 (1.54)
2.2 (1.78)
2.7 (1.91)
2.1 (1.75) 60.37
T10- Control 4.6 (2.63)
5.2 (2.48)
6.2 (2.68)
5.3 (2.50)
- (-152.38)
SEm (±) CD (P=0.05)
(0.08) (0.26)
(0.08) (0.24)
(0.07) (0.23)
(0.08) (0.25)
*Figures in parenthesis are the values of square root transformations: **DAS = Days after spraying ***Percent reduction in thrips over dimethoate
(2.3 thrips/plant) as against 5.3 thrips per plant in untreated control. These treatments
were found most effective in decreasing thrips population to the tune of 66.03 percent
to 33.96 percent with maximum and minimum being recorded in imidacloprid 17.8
SL @0.005% and neem oil (3%), respectively.
Based on these observations it could be concluded that all the test products
including plant products exercised satisfactory in minimizing thrips population on
mungbean but in varying degree. Among all the treatments, significantly better
control of thrips (66.03%) was achieved with two spraying of imidacloprid 17.8 SL
(@0.005%) applied at fortnightly interval starting from bud formation stage, which
was statistically on par to dimethoate 30 EC (60.3%), thiomethoxam 25 WG
(58.49%), profenophos 50 EC (54.71%) and triazophos 35 EC (50.94%) at their test
doses. All the plant products viz; neem oil and yam bean seed extract when applied at
two round spraying were found least effective in respect of suppressing thrips
population (33.96 and 41.50%) on mungbean in comparison to the chemical
insecticides but significantly superior over untreated control. The data related to
mean per cent reduction in thrips population over dimethoate (Table 8) clearly
revealed that except imidacloprid none of the treatments showed its supremacy better
than dimethoate. However, maximum reduction in thrips (14.28%) was recorded with
imidacloprid 17.8 SL (@ 0.005%) over dimethoate. Several workers reported that the
efficacy of various synthetic insecticides used as foliar spray against mungbean thrips
in different parts of the country and abroad. The present findings are in confirmity
with the findings of Borah (1995b) and Borah et al. (1996) who reported that
dimethoate (0.03%) was most effective against control of thrips. Likewise, the results
obtained by foliar spray of imidacloprid (0.005%) was supported by Afzal et al.
(2002) who reported that spray of imicon 25WP at 200 g/acre was found to be most
effective against black thrips. The treatment of profenophos (0.05%), vertimec (9.5
mg a.i/l), diafenthiuron (0.05%) and diflubenzuron (0.05%) were effective next to
dimethoate (0.03%), imidacloprid (0.005%), thiomethoxam (0.05%) and acephate
(0.03%) These results are in agreement with that of Ekesi et al. (2001) and Misra
(2002) who reported that these were moderately effective insecticides against thrips.
Hossain et al. (2004) reported that two spraying of imidacloprid reduced more flower
thrips in mungbean than single one. In the present study effectiveness of
42
thiomethoxam was minimum with compare to imidacloprid and dimethoate, which
supports the finding of Khattak et al. (2004) who investigated that thiomethoxam 25
WG lost its efficacy against thrips 240 hour after spray. Our results are in agreement
with the findings of Chhabra and Kooner (1986) reported that different doses of
malathion, dimethoate, oxydemeton methyl and phosphomidan were tested in five
field trials for controlling the thrips, Megalurothrips distalis Karny.). . Ganapathy and
Karuppiah (2004) and Dhamaniya et al. (2005) reported more or less similar results
that although the neem based preparations and M. anisopliae had imposed reduction
in jassid, whitefly and thrips population but to less extent.
4.3.2 Relative efficacy of synthetic insecticides and plant products against mean
percent pod infestation caused by thrips, Megalurothrips distalis Karny on
mungbean cv. SML 668
The data recorded on effect of synthetic insecticides and plant products on
mean number of pods, mean number of deformed pods per plant and percent pod
infestation caused by thrips, Megalurothrips distalis Karny during the period under
investigation are given in Table 9. The data clearly revealed that the mean number of
pods varied significantly from 31.1 to 48.2 per plant with minimum and maximum
being recorded in untreated control and foliar spray of imidacloprid 17.8 SL (@
0.005%), respectively. Among the remaining treatments thiomethoxam (25 WG),
profenophos (50 EC), triazophos (35 EC) and dimethoate (30 EC) at their respective
doses recorded 45.3, 43.3, 42.4 and 46.4 pods per plant, respectively which were
statistically at par with imidacloprid 17.8 SL (@ 0.005%) but significantly superior
over other treatments and untreated control. Among the plant products neem oil (3%)
and yam bean seed extract (5%) recorded 38.3 and 40.5 pods per plant, respectively
which were inferior than the synthetic insecticides but significantly superior over
untreated control (31.1 pods/plant).
The data recorded on mean number of deformed pods per plant caused by
thrips were varied significantly from 9.2 to 21.4 being minimum and maximum with
imidacloprid 17.8 SL (@ 0.005%) and untreated control, respectively. Among the
remaining treatments foliar spray of dimethoate 30 EC (@ 0.03%) showed better
performance in recording lower number of deformed pods (11.5 pods/plant) which
was statistically at par with imidacloprid 17.8 SL (@ 0.005%) followed by
43
Table 9. Relative efficacy of synthetic insecticides on per cent pod infestation caused by thrips, Megalurothrips distalis Karny on mungbean cv. SML668 during summer season 2015-16.
Treatments
Mean no. of pods/plant
Mean no. of deformed pods/plant
Pod infestation (%) Decrease in pod infestation over
control (%) T1-Spinosad (45 SC) @ 0.045% 39.4 17.0 41.97 38.41
T2- Triazophos ( 35 EC) @ 0.04% 42.4 15.3 36.08 47.05
T3-Thiomethoxam (25WG) @ 0.025% 45.3 12.7 28.03 58.87
T4- Profenophos (50 EC) @ 0.05% 43.3 13.3 30.71 54.93
T5-Imidacloprid (17.8 SL)@ 0.005% 48.2 9.2 19.08 72.00
T6- Fipronil (5 SC) @ 0.05% 41.5 16.6 40.00 41.30
T7- Neem oil @3% 38.3 18.6 48.56 28.74
T8- YBSE @5% 40.5 17.7 44.92 34.08
T9- Dimethoate (30EC )@ 0.03% 46.4 11.5 24.78 63.63
T10- Control 31.1 21.4 68.15 -
SEm (±)
CD (P=0.05)
1.95
5.86
0.96
2.89
1.84
5.53
-
-
thiomethoxam (25 WG), profenophos (50 EC), triazophos (35 EC) with mean number
of deformed pods 12.7, 13.3 and 15.3 pods per plant, respectively at their test doses.
Plant products like neem oil (3%) and yam bean seed extract (5%) were found less
effective in recording lower deformed pod (18.6 and 17.7 pods/plant, respectively) as
compared to synthetic insecticides but significantly superior over untreated control
(21.4 pods/plant).
As it is evident from the data presented in Table 9 clearly revealed that he
mean percent pod infestation varied significantly from 19.08 to 68.15 percent with
minimum and maximum being recorded in imidacloprid 17.8 SL (@ 0.005%) and
untreated control, respectively. However, spraying of dimethoate 30 EC (@ 0.03%)
and thiomethoxam 25 WG (@ 0.025%) showed better performances in recording
lower pod infestation (24.78 and 28.03%, respectively) and occupied 2nd and 3rd
positions after imidacloprid as against 68.15 percent pod infestation in untreated
control. Among the plant products, neem oil (3%) and yam bean seed extract (5%)
were less effective in pod infestation (48.56 and 44.92%, respectively) as compared to
synthetic insecticides but significantly superior over untreated control. The maximum
reduction in pod infestation due to mungbean thrips was recorded in imidacloprid
17.8 SL (@ 0.005%) (72.00%) followed by dimethoate 30 EC (@ 0.03%) (63.63%)
over untreated control. Among the remaining treatments the mean percent pod
infestation was arranged in descending order as follows:
thiomethoxam 25 WG (@ 0.025%) (58.87%)> profenophos 50 EC (@ 0.05%)
(54.93%)> triazophos 35 EC (@ 0.04%) (47.05%)> fipronil 5 SC (@ 0.05%)
(41.30%)> spinosad 45 SC (@ 0.045%) (38.41%)> YBSE (@ 5%) (34.08%) > and
neem oil (@ 3%) (28.74%).
Based on above findings it could be concluded that all the treatments
were found significantly superior in minimizing pod infestation caused by thrips in
varying degree. Among the treatments outright supremacy of two sprayings of
imidacloprid 17.8 SL (@ 0.005%) at fortnightly interval starting from bud formation
stage was the most promising outcome of the present investigation in respect of
recording lowest pod infestation (19.08%) with highest reduction in pod infestation
(72.00%) over untreated control, followed by dimethoate 30 EC (@ 0.03%) and
44
thiomethoxam 25 WG (@ 0.025%). The present findings are in concurrence with
reports of Hossain (2013) and Iqbal et al. (2013).
4.3.3 Phytotonic effect of synthetic insecticides and plant products on mungbean
cv. SML 668
The growth and yield attributing parameters in mungbean as influenced due to
foliar spray of synthetic insecticides and plant products were also assessed and
relevant data are summarized in Table 10. The mean plant height varied significantly
from 59.93 to 84.43cm with minimum and maximum in untreated control and
imidacloprid 17.8 SL (@ 0.005%), respectively which was at par with the other
treatments viz; dimethoate 0.03 percent (82.23cm), thiomethoxam 0.025 percent
(81.76cm), profenophos 0.05 percent (80.80cm), triazophos 0.04 percent (79.66cm),
yam bean seed extract 5 percent (75.13cm) and spinosad 0.045 percent (73.93cm.).
The minimum plant height was recorded in untreated control (59.93cm) followed by
neem oil 3 percent (71.90cm). It could be further seen that the average number of
branches per plant varied significantly from 5.1 to 9.2 per plant under influence of
various treatments (Table 10). It was found to be enhanced by the foliar spray of
insecticides and plant products but in varying degree. Among the different treatments,
effect of insecticides on number of branches was quite apparent (9.2/plant) in case of
imidacloprid 17.8 SL (@ 0.005%) which was statistically at par with dimethoate 30
EC (8.9/plant), thiomethoxam 25 WG (8.1/plant) and profenophos 50 EC (@ 0.05%)
(7.9/plant) as against 5.1 per plant in untreated control. Remaining treatments were
also found better in promoting number of branches per plant except neem oil (3%)
which showed inferior in promoting branches (6.0/plant) and found statistically at par
with untreated control (5.1/plant).
Average number of pods per plant varied significantly from 31.4 to 48.2 with
minimum and maximum being recorded in untreated control and imidacloprid 17.8
SL (@ 0.005%), respectively (Table 10). Among the remaining treatments, foliar
spray of dimethoate 30 EC, thiomethoxam 25 WG, profenophos 50 EC triazophos 35
EC gave better number of pods i.e. 46.4, 45.3, 43.3 and 42.4 pods per plant and found
statistically at par with imidacloprid 17.8 SL (@ 0.005%) when applied at their test
doses. The minimum number of pods per plant was recorded in untreated control
(31.4 pods/plant). Among the plant products neem oil (3%) and yam bean seed extract
45
Table 10. Phytotonic effect of synthetic insecticides and plant products on mungbean cv. SML668 during summer season 2015-16. Treatments Plant height (cm) No. of branches per plant No. of pods per plant
T1-Spinosad (45 SC) @ 0.045% 73.93 7.0 39.4
T2- Triazophos ( 35 EC) @ 0.04% 79.66 7.7 42.4
T3-Thiomethoxam (25WG) @ 0.025% 81.76 8.1 45.3
T4- Profenophos (50 EC) @ 0.05% 80.80 7.9 43.3
T5-Imidacloprid (17.8 SL)@ 0.005% 84.43 9.2 48.2
T6- Fipronil (5 SC) @ 0.05% 76.73 7.3 41.5
T7- Neem oil @3% 71.90 6.0 38.3
T8- YBSE @5% 75.13 7.1 40.5
T9- Dimethoate (30EC )@ 0.03% 82.23 8.9 46.4
T10- Control 59.93 5.1 31.4
SEm (±)
CD (P=0.05)
3.59
10.73
0.44
1.32
1.95
5.89
(5%) showed poor performance as recording mean number of pods (38.3 and
40.5/plant, respectively) but significantly superior over untreated control.
From the foregoing results, it become quite obvious that foliar spray of
insecticides and plant products continued to influenced the subsequent growth and
yield attributing parameters of mungbean. Among the different treatments, foliar
spray of imidacloprid 17.8 SL (@ 0.005%) registered maximum plant height
(84.43cm), average number of branches (9.2/plant) and average number of pods
(48.2/plant). However, these attributes were also highly influenced by dimethoate 30
EC, thiomethoxam 25 WG, profenophos 50 EC triazophos 35 EC with varying level
but equally effective with imidacloprid as compared to other treatments at their test
doses. Hormonic or phytotonic or boosting effect of imidacloprid, dimethoate,
thiomethoxam, profenophos and other insecticides on growth and yield attributing
parameters on mungbean has also been reported by several workers viz; Patel and
Srivastava (1990) and Patel and Sudhani (1990).
4.3.2 Yield of mungbean cv. SML 668 in relation to synthetic insecticides and
plant products spray
Field efficacy of various synthetic insecticides and plant products used as
foliar spray were further adjudged on the basis of grain yield and the relevant data
have been presented in Table 11. Foliar application of synthetic insecticides and plant
products brought about a significant increase in yield of mungbean. Among all the
treatments, foliar spray of imidacloprid 17.8 SL (@0.005%) recorded highest grain
yield (14.8q/ha) which was found statistically on par to dimethoate 30 EC (@ 0.03%)
(13.1q/ha), thiomethoxam 25 WG (@ 0.025%) (13.0q/ha) as against untreated control
(7.2q/ha). Among the remaining treatments foliar spray of profenophos 50 EC (@
0.05%), triazophos 35 EC (@ 0.04%) and fipronil 5 SC (@ 0.05%, gave higher seed
yield of 12.3, 11.8 and 10.5q/ha, respectively with no statistical difference among
themselves. Among the plant products, YBSE (5%) gave significantly higher yield
(9.8q/ha) as compared to untreated control (7.2qa/ha), but statistically on par to neem
oil (3%) (8.9q/ha). All the treatments were found significantly superior in recording
higher grain yield except neem oil (8.9q/ha) applied at their test doses. The mean
percent increase in yield due to application of synthetic insecticides and plant
products over untreated control were arranged in descending order as follows:
46
Table 11. Relative efficacy of synthetic insecticides and plant products on grain yield (q/ha) of mungbean cv. SML668 during summer season 2015-16.
Treatments
Grain yield (q/ha) Per cent increase in yield over control
T1-Spinosad (45 SC) @ 0.045% 9.1 20.87
T2- Triazophos ( 35 EC) @ 0.04% 11.8 38.98
T3-Thiomethoxam (25WG) @ 0.025% 13.0 44.61
T4- Profenophos (50 EC) @ 0.05% 12.3 41.46
T5-Imidacloprid (17.8 SL)@ 0.005% 14.8 51.35
T6- Fipronil (5 SC) @ 0.05% 10.5 31.42
T7- Neem oil @3% 8.9 20.73
T8- YBSE @5% 9.8 26.53
T9- Dimethoate (30EC )@ 0.03% 13.1 45.03
T10- Control 7.2 -
SEm (±)
CD (P=0.05)
0.67
2.00
-
-
imidacloprid 17.8 SL (@0.005%) (51.35%) > dimethoate 30 EC (@ 0.03%)
(45.03%) >thiomethoxam 25 WG (@ 0.025%) (44.61%) > profenophos 50 EC (@
0.05%) (41.46%) >triazophos 35 EC (@ 0.04%) (38.98%) > fipronil 5 SC (@ 0.05%)
(31.42%) > YBSE (@ 5%) (26.53%) > spinosad 45 SC (@ 0.045%) (20.87%) > neem
oil @3 % (20.73%).
From the forgoing results it could be concluded that the foliar application of
imidacloprid 17.8 SL (@0.005%) yielded more (14.8qa/ha) than other synthetic
insecticides and plant products used as foliar application but did not differ statistically
with dimethoate 30 EC (@ 0.03%) (13.1q/ha) and thiomethoxam 25 WG (@ 0.025%)
(13.0q/ha) as against untreated control (7.2q/ha). Among the plant products except
YBSE (5%) none was found to performed better than untreated control. The results
reported by earlier workers viz: Gour and Pareek (2003) who reported that maximum
yield was obtained in dimethoate (0.03%) followed by imidacloprid (0.05%) and
acephate (0.05%) are in agreement with the present findings. Azam et al. (2008)
reported that application of furadan 5G as a seed treatment gave the maximum yield
(950.5 kg/ha). Hossain et al. (2013) found that in double spraying plots with
imidacloprid, the yield of mungbean was the highest (1457kg/ha) against the lower
yield (725kg/ha) with the same insecticide in the single treated plots. The present
findings are similar to the reports of them. They reported that the highest seed yield
(8.11 q/ha) was found in plots treated with dimethoate (0.03%) followed by
imidacloprid 0.005 per cent (7.85 q/ha), thiomethoxam 0.05 per cent (7.51 q/ha). The
next best group comprised acephate (0.037%), profenophos (0.05%) and vertimec (9.5
mg a.i/l) which gave seed yield of 6.69, 6.59 and 6.52 q/ha, respectively.
4.3.4 Cost- benefit analysis of synthetic insecticides and plant products used as
crop protectant
Field efficacy of synthetic insecticides and plant products used as foliar spray
under test was finally assessed and compared on the basis of benefit realized in
monetary term and the data pertaining to the economics are presented in Table 12.
The gross income accrued due to different treatments was the highest Rs. 68400/ha in
case of imidacloprid 17.8 SL (@0.005%) while it was lowest Rs. 15300/ha in foliar
application of neem oil @ 3%. Remaining treatments occupied intermediate positions
with wide difference in this respect. The net profit derived out of different treatments
47
Table 12. Economics of synthetic insecticides and plant products used as foliar spray for the management of thrips, Megalurothrips distalis Karny on mungbean cv. SML 668 during summer season 2015-16. Treatments
Additional yield over
control (q/ha)
Price of additional yield
(Rs/ha)
Cost of treatment
(Rs/ha)
Net profit/loss over control
(Rs/ha)
Benefit-cost ratio
T1-Spinosad (45 SC) @ 0.045% 1.9 17100 15164 1936 8.83:1
T2- Triazophos ( 35 EC) @ 0.04% 4.6 41400 1780 39620 23.25:1
T3-Thiomethoxam (25WG) @ 0.025% 5.8 52200 2514 49686 20.76:1
T4- Profenophos (50 EC) @ 0.05% 5.1 45900 2314 43586 19.83:1
T5-Imidacloprid (17.8 SL)@ 0.005% 7.6 68400 1584 66816 43.18:1
T6- Fipronil (5 SC) @ 0.05% 3.3 29700 13664 16036 2.17:1
T7- Neem oil @3% 1.7 15300 24930 -9630 0.61:1
T8- YBSE @5% 2.6 23400 30930 -7530 0.75:1
T9- Dimethoate (30EC )@ 0.03% 5.9 53100 1484 51616 35.78:1
T10- Control - - - - -
Selling price of mungbean: Rs. 9000/q, Cost of insecticides viz; Spinosad (45 SC) =Rs.14000/lit, Triazophos (35 EC) =Rs. 440/lit,
Thiomethoxam (25WG) = Rs. 1350/kg, Profenophos (50 EC) =Rs.1150/lit, Imidacloprid (17.5 SL) =Rs.1500/lit, Fipronil (5SC) =Rs.
1250/lit, Neem oil (3%)=Rs.400/lit, YBSE (5%) = 300/kg, Dimethoate (30EC ) = Rs. 320/lit., respectively. No. of labourers per ha = 3,
Wages of each labour = @ Rs. 194. Total no of labours = 6, Total wages = Rs. 1164/ha.
got affected since cost involved in these treatments ranged from Rs. 1484 to Rs.
30930/ha with minimum and maximum being in dimethoate and yam bean seed
extract, respectively. The net profit derived under different treatments varied widely
and it was the highest Rs. 66816/ha in case of imidacloprid 17.8 SL (@0.005%) and
the lowest Rs. 1936/ha in spinosad 45 SC (@ 0.045%). Among the remaining
treatments foliar application of dimethoate 30 EC (@ 0.03%) occupied second
position by earning net income of Rs. 51616/ha followed by thiomethoxam 25 WG
(@ 0.025%) (Rs. 49686/ha), profenophos 50 EC (@ 0.05%) (Rs. 43586/ha),
triazophos 35 EC (@ 0.04%) (Rs. 39620/ha) and fipronil 5 SC (@ 0.05%) (Rs.
16036/ha). But YBSE (@ 5%) and neem oil (@3 %) were not found economical and
net loss was recorded to be Rs. 7530/ha and Rs. 9630/ha, respectively. This might be
due to higher cost involved in spraying of these two plant products and poor yielder.
Consequently benefit – cost ratio of insecticides and plant products used as foliar
spray differ remarkably. It was the highest (43.18:1) in case of imidacloprid 17.8 SL
followed by dimethoate 30 EC (35.78:1), triazophos 35 EC (23.25:1), thiomethoxam
25 WG (20.76:1), profenophos 50 EC (19.83:1), spinosad 45 SC (8.83:1) and fipronil
5 SC (2.17:1). On the other hand foliar application of neem oil and YBSE each at 3
and 5 percent were not found economical with benefit cost ratio of 0.61:1 and 0.75:1,
respectively.
On the basis of the above findings it becomes obvious that the investment in
foliar application of imidacloprid 17.8 SL (@0.005%), dimethoate 30 EC (@ 0.03%),
thiomethoxam 25 WG (@ 0.025%), profenophos 50 EC (@ 0.05%), triazophos 35 EC
(@ 0.04%), fipronil 5 SC (@ 0.05%) and spinosad 45 SC (@ 0.045%) proved most
profitable while neem oil and YBSE at their test doses were not profitable. More or
less similar results was obtained by Ujagir and Chaudhary (1997) and Anonymous
(2000) who reported that highest benefit cost ratio was obtained in the plots treated
with dimethoate (0.03%) in green gram crop. The negative benefit cost ratios were
recorded in the plots treated with diflubenzuron, thiomethoxam and vertimec due to
their high market price. Hossain et al. (2013) reported that the highest monetary
benefit (4.67) was obtained from double spraying of imidacloprid at 42 DAS and 49
DAS which was close to single spraying (4.19) at 42 DAS in mungbean crop.
48
SUMMARY
The thrips, Megalurothrips distalis Karny (Thysanoptera: Thripidae) is the
most serious insect pest of summer mungbean acts as one of the limiting factor in the
successful cultivation of the crop. Both the nymphs and adults directly puncture sub-
epidermal cell of plant tissue and suck the cell sap leaving white patches on the
affected plants, the affected leaves, flowers become wrinkled, twisted and dry up
causing poor yield besides transmitting several viral diseases. Keeping in view of loss
caused by this pest on summer mungbean, the pulse growers have been largely
depending on the use of chemical insecticides, with little or no attention to ecological
complications arising out of indiscriminate use of insecticides. With a view to study
the population dynamics of Megalurothrips distalis in relation to abiotic factors on
mungbean besides developing strategies for its managements through manipulation in
dates of sowing and optimized foliar spray of synthetic insecticides and plant products
were carried out during the summer season i.e. 2015-16. All the field experiments
were conducted at the research farm, T.C.A. Dholi, Muzaffarapur, Bihar, which
represents the agro climatic zone-1 of Bihar falls in the middle gangetic planes
regions belonging to North eastern plane zone i.e. agro climatic zone- 4 of India. The
present study generated useful informations pertaining to the population build up in
relation to abiotic factors, manipulation in sowing dates and relative efficacy of foliar
application of synthetic insecticides and plant products. Results so obtained are
summarized below:
The activity of thrips commenced from 17th standard week of April, 2015 and
continued till the pod maturity stage of the crop (24th standard week of June, 2015)
with maximum population (5.6 thrips/plant) was observed on 22nd standard week of
June, 2015. The weather parameters viz; maximum, minimum temperature (oC),
relative humidity (%) at 07 and 14 hrs and rainfall (mm) were 40.5, 27.5, 87.7, 46.7
and nil, respectively which were found to be congenial for thrips population build-up.
The mean number of thrips per flower was initially observed on flower in 18th
standard week of May, 2015 and continued till the pod maturity stage of the crop (20th
standard week of May, 2015). The maximum population (6.6 thrips/ flower) was
5
observed on 18th standard week of May, 2015 when the maximum, minimum
temperature (oC), relative humidity (%) at 07 and 14 hrs and rainfall (mm) were 34.5,
21.3, 89.5, 66.1 and nil, respectively.
Relationship among thrips population with meteorological parameters like
maximum, minimum temperature (oC), relative humidity (%) at 07 and 14 hrs and
rainfall (mm) were determined by computing correlation coefficient (r) analysis. The
maximum temperature and minimum temperature showed highly positive association
with thrips population (r= 0.628 and 0.339). The relative humidity recorded at 7 hrs
and 14 hrs showed highly significant negative effect on thrips population (r= -0.576
and -0.769). However, the rainfall recorded during the crop period was very high i.e.
25.8 mm therefore, their effect was too much pronounced and showed significant
negative effect on thrips population (r= -0.599). However, the weather parameters
together govern 71.9 percent towards the change in thrips population of mungbean
crop.
The mungbean crop sown up to 1st week of April was found to suffer least due
to lower level of thrips population ranging from 2.8 to 2.4 thrips per plant when crop
was sown between 24th March 2015 to 1st April 2015. Delaying in its sowing
afterwards carry higher population of thrips (3.4- 6.2 thrips/plant). The crop sown on
20th April 2015 harbour maximum number of thrips (6.2 thrips/plant) might be due to
increase in temperature and dry weather prevailing during the vegetative stage of the
crop. The lowest thrips population (1.0 and 1.6 thrips/flower) was recorded when crop
sown on 1st April 2015 with cumulative mean number of thrips (1.3 thrips/flower).
The highest thrips per flower was recorded to be 4.0 and 5.8 with cumulative mean
number of thrips 4.9, when crop sown on 20th April 2015. Among different dates of
sowing 1st April proved to be the most suitable date of sowing in respect of
increasing more number of pods per plant (47.37/plant), lowest number of deformed
pods (5.35/plant) and lowest mean percent pod infestation (11.17%). Highest grain
yield of 14.6q/ha was obtained on 1st April followed by 24th March 2015 (11.4q/ha)
and occupied second position. Delay in sowing after 1st April brought about
progressive decrease in grain yield.
50
Among the synthetic insecticides and plant products under test, significantly
better control of mungbean thrips was achieved with two round spraying of
imidacloprid 17.8 SL (@0.005%) applied at fortnightly interval starting from bud
formation stage, which was statistically on par to dimethoate 30 EC, thiomethoxam 25
WG, profenophos 50 EC and triazophos 35 EC, at their test doses. Among the plant
products neem oil (3%) and yam been seed extract (5%) showed poor performance as
compared to the synthetic insecticides but significantly superior over untreated control
in respect of minimizing thrips population varied from 2.6 to 4.2 and 2.4 to 3.8 thrips
per plant, respectively. These treatments were found most effective in decreasing in
thrips population to the tune of 66.03 percent to 33.96 percent with maximum and
minimum being recorded in imidacloprid 17.8 SL @0.005% and neem oil (3%),
respectively. All the plant products viz; neem oil (3%) and yam bean seed extract
(5%) when applied twice at fortnightly interval, were found least effective in
suppressing thrips population (33.96 and 41.50%) on mungbean in comparison to the
chemical insecticides but significantly superior over untreated control.
All the treatments were found significantly superior in minimizing pod
infestation caused by thrips in varying degree. Among the treatments outright
supremacy of two sprayings of imidacloprid 17.8 SL (@ 0.005%) at fortnightly
interval starting from bud formation stage was the most promising outcome of the
present investigation in respect of recording lowest pod infestation (19.08%) with
highest reduction in pod infestation (72.00%) over untreated control, followed by
dimethoate 30 EC (@ 0.03%) and thiomethoxam 25 WG (@ 0.025%). The foliar
spray of insecticides and plant products continued to influences the subsequent
growth and yield attributing parameters of mungbean. Among the different
treatments, imidacloprid 17.8 SL (@ 0.005%) registered maximum plant height
(84.43cm), number of branches (9.2/plant) and number of pods (48.2/plant). However
these attributes were also highly influenced by dimethoate 30 EC, thiomethoxam 25
WG, profenophos 50 EC triazophos 35 EC with varying level but equally effective
with imidacloprid as compared to other treatments at their test doses. The foliar
application of imidacloprid 17.8 SL (@0.005%) yielded more (14.8qa/ha), than other
synthetic insecticides and plant products used as foliar application but did not differ
statistically with dimethoate 30 EC (@ 0.03%) (13.1q/ha), thiomethoxam 25 WG (@
51
0.025%) (13.0q/ha), as against untreated control (7.2q/ha). Among the plant products
except YBSE 5% none was found to perform better than untreated control.
Finally on the basis of economics parameters, different synthetic insecticides
and plant product treatments varied widely from each other. The gross income
accrued due to different treatments was the highest Rs. 68400/ha in case of
imidacloprid 17.8 SL (@0.005%) while it was lowest Rs. 15300/ha in foliar
application of neem oil @ (3%). Remaining treatments occupied intermediate
positions with wide difference in this respect. The net profit derived out of different
treatments got affected since cost involved in these treatments ranged from Rs. 1484
to Rs. 30930/ha with minimum and maximum being in dimethoate and yam bean seed
extract, respectively. The net profit derived under different treatments varied widely
and it was the highest Rs. 66816/ha in case of imidacloprid 17.8 SL (@0.005%) and
the lowest Rs. 1936/ha in spinosad 45 SC (@ 0.045%). Among the remaining
treatments foliar application of dimethoate 30 EC (@ 0.03%) occupied second
position by earning net income of Rs. 51616/ha followed by thiomethoxam 25 WG
(@ 0.025%) (Rs. 49686/ha), profenophos 50 EC (@ 0.05%) (Rs. 43586/ha),
triazophos 35 EC (@ 0.04%) (Rs. 39620/ha) and fipronil 5 SC (@ 0.05%) (Rs.
16036/ha). But YBSE (@ 5%) and neem oil (@ 3%) were not found economical and
net loss was recorded to be Rs. 7530/ha and Rs. 9630/ha, respectively. The
highest(43.18:1) B:C ratio was achieved in case of imidacloprid 17.8 SL followed by
dimethoate 30 EC (35.78:1), triazophos 35 EC (23.25:1), thiomethoxam 25 WG
(20.76:1), profenophos 50 EC (19.83:1), spinosad 45 SC (8.83:1) and fipronil 5 SC
(2.17:1). On the other hand foliar application of neem oil and YBSE each at 3 and 5
percent were not found economical with benefit cost ratio of 0.61:1 and 0.75:1,
respectively.
52
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Anonymous, 1999. Annual Progress Report. All India Coordinated Research Project
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(P.G. FORM – III)
RAJENDRA AGRICULTURAL UNIVERSITY, BIHAR
SYNOPSIS OF THESIS PROBLEM OF POST-GRADUATE STUDENT
Post-Graduate Degree Programme : M.Sc. (Agri). Department : Entomology Name of Student : GAJJALA.CHARAN KUMAR REDDY Admission No./Registration No. : M/Ento./141/2014-15 Major Subject : Entomology Minor Subject : Plant Pathology Major Advisor : Dr. RABINDRA PRASAD Title of the Research problem : “Management of thrips (Megalurothrips
distalis Karny) on green gram (Vigna radiata) through dates of sowing and insecticides”
INTRODUCTION Among the grain legumes mung bean also known as green gram (Vigna
radiata) is an important pulse crop grown in summer and kharif seasons in different parts of India in general and Bihar in particular. It is a short duration crop, fits in various multiple cropping and intercropping system and grown as catch crop. Besides, serving as food and fodder for large segment of population and animals, it also fixes atmospheric nitrogen in root nodules and can be incorporated as green manure in order to enhance the soil fertility.
Pulse crops have immense potentiality to provide food and nutritional security to large segment of population especially vegetarian people who are mainly dependent on pulses as source of protein. The available protein to people in India has come down steeply due to high cost of animal protein on one side and low production of pulses on the other. Due to insufficient production of pulse the requirement of the fast growing population results into progressive decline in its availability from 60 gm/capita/day during 1961 to 50 gm/capita/day in 2012-13, while 80-100 gm/capita/day is the minimum requirement for a balance diet. This can be achieved only by increasing the area, production, and productivity of all pulses including green gram.
Among grain legumes grown in Bihar, green gram occupies 147.30 thousand hectare area, with total production 88.38 thousand tonnes and an average productivity of 600kg/ha (Anonymous,2012). But the productivity has steeply comedown in changing climate scenario due to wide range of biotic and abiotic constraints. Among biotic constrains, insect pests cause a considerable loss in yield of mung bean. About 60 species of insects are known to attack mung bean during summer and kharif
seasons at different growth stages. Thrips Megalurothrips distalis has been reported as a major pest causing severe field loss (40-89%) in Punjab (Chhabra and Kooner, 1985). Both nymphs and adults suck the plant cell sap from bud and flowers resulting shedding of flowers, twisting of pods without grains. High yield reduction was observed in Bihar particularly during summer season.
Keeping in view of the above it is pertinent to know the population build up of thrips and work out suitable management strategies through cultural and insecticide application based on ecological consideration. The present investigation is, therefore, proposed to be undertaken with the following objectives:
4. Population dynamics of thrips on green gram with relation to abiotic factors. 5. Effects of dates of sowing on the incidence of thrips on green gram. 6. Ascertaining the field efficacy of some synthetic insecticides and plant
products against thrips on green gram. A BRIEF RESUME OF WORKS DONE IN INDIA AND ABROAD
A brief account of the work done on different aspects, viz. population dynamics and management through cultural and chemical control of thrips on green gram both in India and abroad are presented below.
Several workers have reported that the incidence of thrips on green gram is the highest in summer and low in rainy crop. The incidence of thrips started at flower initiation stage and maximum population (57.2/100 flowers) was recorded at 57-63 days after sowing (Kumar, et.al., 2007). Thrips was reported to be the most serious pest causing high yield loss in green gram grown during summer season at Ludhiana. Maximum population of thrips on green gram was recorded during 2nd week of May (Gupta and Singh, 1993). They also reported that the thrips showed significant negative correlation with relative humidity and significant positive correlation with sunshine hour.
Little or no efforts seem to have been made for management of thrips on green gram through manipulation in sowing dates particularly in Bihar situation. However, a few workers, viz. (Sreekanth et.al., 2002 and Hossain et.al., 2009) reported appropriate sowing time at which thrips population remained lowest and thus resulting in higher seed yield.
Conventional control method of thrips on green gram through insecticides either as seed treatment or foliar spray have been tried by several workers from time to time in different parts of the country with varying degree of success (Chhabra and Kooner,1985; Kumar et.al., 2007). But least attempt seems to have been made to study the efficacy of insecticides and ecofriendly botanical pesticides applied as foliar spray against thrips on green gram suited to agroecological conditions of Bihar. TECHNICAL PROGRAMME
1. In order to study the population dynamics of thrips on green gram a field experiment will be conducted at T.C.A Dholi farm with variety SML 668. The crop would be sown in a plot of 10x10 sq.m. area during last week of March
following normal agronomic practices except insecticidal application. The population of thrips would be recorded at weekly intervals on three leaves, viz. one each from top, middle, and lower canopy of five randomly selected plants and 20 randomly selected flowers. The population will be recorded in the early morning hours. The collected leaves and flowers would immediately be kept in a polythene bag containing ethyl acetate soaked cotton bolls to kill the thrips enabling easy counting. The population will be counted through hand lens. Mean number of thrips per leaf and flower per plant would be worked out and data would be correlated with the meteorological parameters to ascertain the effect of abiotic factors on the population of thrips. The impact of abiotic factors on population build up of thrips would be worked out by using regression analysis.
2. In order to explore the possibility of management of thrips on green gram through manipulation in dates of sowing, a field experiment would be conducted at research farm, T.C.A Dholi Farm in R.B.D with five different dates of sowing at ten days intervals starting from 24th March, and each treatment will be replicated four times. The green gram cv. SML 668 would be grown as per recommended package of practices without any insecticide application. The seed will be sown in row at plant spacing of 30x10 cm with a plot size of 2.0x1.80 m.
Observations to be recorded: 1. Plant infestation (number of deformed pods) in per cent 2. Seed yield (q/ha) 3. Test weight of 100 seed Observations pertaining to per cent thrips population would be
assessed on 20 flowers, randomly collected from two middle rows from each plot. The per cent plant infestation would be determined on the basis of deformed pods to be recorded on ten plants randomly selected from each plot. The observations would be recorded at weekly intervals starting from flower initiation stage. Finally the seed yield will be recorded at the time of harvesting.
3. To test field efficacy of some insecticides viz. Spinosad (0.045%), Triazophos (0.04%) Thiomethoxam (0.025%), Profenophos (0.05%) Imidacloprid (0.005%), Fipronil (0.05%), and plant products viz. neem oil (3%), yam bean seed extract (5%), dimethoate @ 0.03% (standard check) and untreated control against thrips on green gram, a field experiment will be conducted at T.C.A Dholi Farm, Muzaffarapur, (Bihar) during summer season. The experiment would be conducted in R.B.D with ten treatments and each treatment will be replicated thrice. The crop (var.SML 668) will be grown as per recommended package of practices. Spraying will be done twice at fortnightly interval starting at bud formation stage.
Insecticide/ Plant products Doses of application 1. Spinosad(45% SC) 0.045% 2. Triazophos (35%EC) 0.04% 3. Thiomethoxam (25% WG) 0.025% 4. Profenophos (50% EC) 0.05% 5. Imidacloprid (17.8%SL) 0.005% 6. Fipronil (5%SC) 0.05% 7. Neem oil 3% 8. Yam bean seed extract 5% 9. Dimethoate (30%EC)(standard check) 0.03% 10. Control (untreated)
Observations to be recorded:
1. The mean per cent deformed pod 2. Yield data (q/ha) 3. The phytotonic effect of the treatments, if any.
Observations pertaining to thrips population would be recorded at one day before application and one, five and ten days after application of each treatment on 20 randomly selected flowers. The mean per cent deformed pod will be recorded on ten randomly selected plants in each treatment at the time of pod maturity stage. The yield data would be recorded after harvesting of the crop and will be computed per hectare. The phytotonic effect of the treatments would also be recorded in terms of number of branches, number of pods per plant and height at 10 days after second application of treatments on five randomly selected plants.
COLLABORATION WITH OTHER DEPARTMENT 1. Deptt of Plant Pathology, T.C.A, Dholi, Muzaffarapur. 2. Deptt of Statistics, Mathematics and Computer applications.
Facilities from supporting and minor deptt. will be taken as and when required. REFERENCES
Anonymous. (1988). Effect of sowing date and insecticides against thrips, stem fly and pod borer of black gram. Annual Report 1997/1998. Bangladesh Agricultural research Institute (BARI). Joydebpur, Gazipur, Bangladesh. Pp 104-105.
Anonymous,(2012) Directorate of economics and statistics, Govt.of Bihar. Baldev, B., Ramanujam, S. and Jain, H.K. (1988). Pulse Crops. Oxford IBH
Publishing Co. Pvt .Ltd. New Delhi, pp 229-258. Chhabra, K.S. and Kooner, B.S. (1983) Losses in summer mung bean due to insect
pest in Punjab. Proceeding of National Seminar on crop losses due to insect pests. Entomological Society of India, held at APAU. Hyderabad, January pp 7-9.
Chhabra, K.S. and Kooner, B.S. (1985), Problem of flower shedding caused by thrips on Summer mung bean, (Wilczek), and its control.Tropical Pest Management, 31: 186-188.
Gupta.P.K, and Singh. J. (1993) Population studies on insect pests of green gram Indian Journal of Entomology 55(1): 45-51.
Hossain, M.A., Ferdous, j., Sarkar,M.A. and Rahman, M.A. 2004. Insecticidal Management of thrips and pod borer in mung bean. Bangladesh Journal of Agricultural Research, 29(3): 347-356.
Kumar. P.K and Singh.D.C, and Singh.R (2007) Evaluation of newer insecticides for the Management of major insect pests of urd bean (Vigna mungo (L.) Hepper) National symposium on legumes for ecological sustainability, November 3-5 pp 132.
Kooner, B.S., Chhabra, K.S. and Verma, M.M. (1982) Pest problems in summer mung bean in the Punjab. Proceedings Pulse Research Workers Summer/spring mung and urd Workshop. Directorate of Pulse Research, January 30-31, 1982, Kanpur.
Lal, S.S. 1985. A review of insect pests of mung bean and their control in india. Tropical Pest Management,31(2): 105-114.
Ruesink, W.G. and Kogan. M. (1975). The quantitative basis of pest management: Sampling and measuring. (In) Introduction to insect pest management. (Eds). Metecalf. R.L. and Luckmann. W.R. Pub. John Willey and sons. New York : Pp 309-351.
Singh, K.M. and Singh, R.N. (1977). Succession of insect pests of green gram and black gram under dry land condition at Delhi. Indian journals of Entomology.39(4): 365-436.
Sreekanth, M., Sreeramulu, M., Rao, R.D.V.J., Prasada Babu, B. Sarath; Babu, (2002): Effect of sowing date on thrips palmi Karny population and pea nut bud Necrosis virus incidence in green gram. Indian Journal of Plant Protection, 30(1): 16-21.
Major advisor Dr. Rabindra Prasad Jr.Scientist-Cum-Asstt.Prof. Deptt of Entomology. T.C.A, Dholi. Members
1.Dr.P.P.Singh (Major subject) Sr.Scientist-Cum-Assoc.Prof. Deptt of Entomology. T.C.A, Dholi. 2.Dr.A.K.Mishra (Minor Subject) Jr.Scientist-Cum-Asstt.Prof. Deptt of Plant Pathology T.C.A, Dholi. 3.Dr.K.N.Pathak (Dean’s Nominee) University Prof. Deptt of Nematology Dr.RPCAU. PUSA.
Forwarded 6 copies to the DRI-cum Dean P.G for approval:-
APPROVED Assoc.Dean Head of the Deptt. Director, Resident Instruction –Cum- Dean Faculty of P.G Studies.
Note:Study programme is to be submitted by the end of the first semester of student’s stay