nadeemawan17@gmail.com

Muhammad Nadeem Ashraf

2013-ag-10M.Sc(Hons) Soil Science

INSECT PESTS OF COTTON CROP AND THEIR MANAGEMENT

INTRODUCTION

Insects represent a widely studied group of arthropods having diversity in their habitat and life forms.

Adaptation of insects may be directly correlated with the successful evolution history.

Scientists are working day and night to find the successful adaptation of insects to their environment.

Cont… The plants on which insect feeds are called as host plants.

Some insects are monophagous and feed on one plant species. Others are called as polyphagous and are having a diverse range of feeding and living.

Although the pest management techniques are still proving to be reasonable to some extent but the insects are coming up with an ever increasing resistance mechanism that are supporting their life forms as well as strengthening their next generations.

COTTON INTRODUCTION Cotton serves as a perfect host for variety of insects.

Cotton is widely grown in South Asia mainly due to the perfect atmospheric and topographic features.

Insect pests of cotton in Pakistan represent the greatest diversity in the whole region.

More than 1300 species of insects are found attacking on Cotton crop and more than 93 insects and mites are found damaging for the cotton crop in Pakistan.

INSECTS OF COTTON1. Whitefly

2. Jassid

3. Thrips

4. Mealy Bug

5. Dusky Cotton Bug

6. Army Worm

7. American Boll Worm

8. Spotted Boll Worm

9. Pink Boll Worm

10. Cotton Leaf Folder

Whitefly Bemisia tabaci is said to be the most notorious pest of

American cotton mainly due to its ability to transmit the CLCV also called as the Cotton Leaf Curl Virus.

Cont… Whitefly damages the cotton crop in four ways:

1. It sucks the cell sap and results in loss of vigor.

2. It also injects the toxic saliva that results in a great damage to the cotton leaves.

3. It also injects the toxic saliva that results in a great damage to the cotton leaves.

4. It sucks the cell sap and secretes the honey dew that invites the infestation of sooty mould.

Harmful Effect of whitefly

Sickly black appearance of the plant results in less absorption of sunlight and the photosynthesis process is adversely affected in one way or the other.

Transmission of CLCV is one of the most important damage of cotton whitefly.

Jassid Amrasca biguttula is one of the most damaging pests of

cotton crop in Pakistan.

Cont… Damage of Cotton Jassid is very different as compared to that

of other insect pests of cotton. Cup formation of leaves is observed in the peak of its attack. It also secretes the toxic secretions that are passed along with

the saliva and the plant metabolism gets a greater shock due to the very presence of this particular insect pest of cotton.

It also disturbs the boll formation as the boll formation is reduced after the attack of Jassid.

It also affects the ladyfinger crop and also causes a greater damage to the winter vegetables which serves as an alternate source of food when the cotton season is not in progress.

Thrips Thrips tabaci is one of the most threatening pests of

cotton, onion and garlic.

Thrips Damaging The rasping sucking mouth parts of this insect damages the

vegetative as well as the reproductive parts of many crops. In cotton the attack of thrips is greatly observed on the flowers

and leaves where it congregates near the base of flowers or the leaves.

Most of the farmers get the confusion in determining the attack of thrips. The mode of damage is different as compared to other insect pests of cotton.

Crumpled and silvery appearance of leaves is the main sign of the thrips attack on American cotton.

In many countries like USA thrips is considered to be the vector of many viruses like the streak virus of peas and yellow spot of pineapple.

Mealy Bug Phenococcus gossypiphilous was first reported in 2005 in

Pakistan and in 2006-07 it affected the whole cotton belt of Pakistan.

Cont… Life cycle of mealy bug is very rapid and it feeds on almost

all kind of vegetables and flowers mainly due to the polyphagous habit.

It damages the cotton crop by sucking the cell sap and decreasing the plant vigor.

It also secretes some toxic saliva secretions that inhibit the growth and disturbs plant metabolism.

It can also secrete the cottony wax and when the attack exceeds the threshold level honey dew also increases in percentage and so is the sooty mold.

Dusky Cotton Bug Oxycarenus laetus was considered to be the minor pest of

Cotton but now it is going to become the possible threat to the early and late cotton crop in Pakistan.

Cont.. Sucking behavior of this insect disturbs the cotton crop at

early as well as the late stages. It sucks the sap from the reproductive parts of plants and

it can also deteriorate the seed quality. It also deteriorates the lint quality resulting in poor

ginning of cotton fibers. It gives the staining to the lint and the lint of low quality

gets the lower price in market. It is found on cotton, ladyfinger and other malvaceous

plants.

Army Worm Spodoptera litura is counted among the major insect pests

of cotton crop in Pakistan.

Cont.. It damages the crop due to its chewing behavior. Most important sign of its attack is the damaged leaves that

are in the form of empty areas. It feeds the leaves in between the veins and the veinlets.

Skeleton of the leaves dries up due to the inactivation of photosynthetic processes.

This result in the loss of vigor of plant and the quality of boll is affected.

Attacked fields have lower yield of bolls as compared to that of the healthy fields.

Cont.. IPM practices are there as there are many types of biological

as well as cultural control methods of this insect.

If none of the control methods seem to be working then chemical control is perhaps the last and considered to be most effective option for the control of insect pests of cotton.

It is not a problem in BT Cotton.

American Boll Worm Helicoverpa armigera is also called as the American

bollworm and it is an important pest of chickpea and American Cotton. It is a polyphagous insect and is considered to damage a range of vegetable and other crops in Pakistan as well as other countries of South Asia.

Cont.. When it attacks the early stages it hollows the squares from

inside and the damaged squares fall on the ground. It directly affects the cotton crop and results in lower yields.

When the boll is mature it makes a prominent hole on the boll and results in the damage of the crop.

The damage of American Bollworm is not observed in a uniform behavior rather it attacks in patches and affects the crop in patch.

It shifts from one boll to another and damages dozens of bolls during life time.

Cont..

Biological control of this insect is the best option but in

harsh conditions when biological control is not effective,

chemical control serves as the only option for the control

of American bollworm.

It is not a problem in BT Cotton.

Spotted Boll Worm Earias insulana is also called as the spotted bollworm of

cotton. It damages many parts of cotton crop and most of the times it is found boring in the reproductive as well as the vegetative parts of cotton.

Cont.. Premature opening of cotton boll is said to be the most

important indication of the attack of spotted bollworm.

It deteriorates the lint quality and results in lesser profits.

It is not a problem in BT Cotton.

Pink Boll Worm Pectinophora gossypiella is one of the most destructive

pests of cotton crop in Pakistan.

Cont.. It attacks the flowering stage when the female lays eggs on the

base of flower. The larvae make a very small hole and move inside the

flower. The affected boll fails to open or it opens in a very awkward

fashion indicating the attack of pink boll worm. It hibernates in between the seeds and Double Seeds are also

the best indication of the damaged seeds. Farmers should avoid the use of Double Seeds that are stuck

together by the silken threads of pupal stage of this pest. Cotton sticks serve as the best hiding place for this insect. It is not a problem in BT Cotton.

Cotton Leaf Folder Sylepta derogata is also called as the cotton leaf folder. As

the name is indicating the pest makes the leaves to roll.

Cont.. The older larvae roll the edges of leaves with the help of

silken threads and feed on the leaf tissues after making roll.

Biological control is considered to be optimum in case of the ideal conditions of temperature and humidity.

During harsh conditions, chemical control is only option left.

Attack of this pest is less on Native Cotton or Local Cotton.