Importance of PestsIntroductionA pest is an organism which is detrimental to humans or human interest. Organism designated as pests compete with humans for food (e.g. rice brown planthopper), fibre and shelter (e.g. cloths moth), transmit pathogens (e.g. mosquito), feed on human blood (e.g. head louse), or otherwise threaten human health (e.g. house fly), comfort or welfare (e.g. rats). Rice brown planthopperMus boodugaNext

Prior to the appearance of human, there were no pests on the earth. The term pest is anthropogenic by considering humans as the central fact and it is circumstantial. For example termites feeding on dead wood in a forest serve an important degrader of organic matter, thus returning nutrients to the soil. Clearly, termites are not pests in this context; they are beneficial. The same species, in a human home, is an important pest. Therefore, an organisms can be pest at one place and not at another. Termite moundsEndPreviousNext

Types of PestsOrganisms that have become pests are not limited to any one class or phylum. Insects are the most frequent pest and it is no wonder, since they make up more than 75% of the worlds animal species. A number of mites, ticks, nematodes, mollusks and other invertebrate species act as pests. Vertebrates, including rodents, deer and birds, may become serious pests in some situations. Microorganisms e.g., bacteria, fungi, protozoa, rickettsia, viruses and mycoplasmas particularly those causing diseases to important plants and animals cause are also categorized as pests. Tomato fruit borerBlue bull (Nilgai)EndPreviousNext

Agricultural PestsGreatest share of pest problems is encountered in agriculture and forest production systems. Here, problems arise because of large numbers of insects. Most insect pests of agriculture are those species which cause economic losses due to their high populations. These include insects like stem borers, cutworms, armyworms, fruit borers, fruit flies, leaf miners, leaf folders, termites, white grubs, leaf and plant hoppers, grasshoppers, mealy bugs, aphids, whiteflies, thrips etc. Also included in agricultural pests are non-insect pests such as nematodes, snails and slugs, mites, rodents, birds, monkeys and other animals.

GrasshopperLeaf minerEndPreviousNext

Pest categories based on StatusRegarding pest status following two terms must be understood.a. General equilibrium position (GEP)The GEP refers to long-term average population of a pest species in a location.b. Economic injury levelThe EIL signifies minimum pest population, which causes economic damage. Economic damage is that amount of damage, which has monetary value is at least equal to expenditure on control action, which is undertaken to prevent pest damage. For example if pest causes damage worth Rs. 1000 but expenditure on control is Rs. 1200, then pest damage is not economic. The damage will be economic only when its monetary value will be at least Rs. 1200. Blister beetles on bajraEndPreviousNext

A. Regular pestsThese are those pests which cause damage every year regularly. They have the GEP below the EIL but it is very close to the EIL. Economic damage thus occurs in most years hence control measures are required frequently to bring down the pest population e.g. tobacco caterpillar, Spodoptera litura, a pest of cruciferous vegetables pests.B. Severe pests Severe pests are those pests in which EIL is below the GEP level e.g. Chilo partellus, maize stem borer. Perennial and severe pests are together called major or key pests. Spodoptera lituraEndPreviousNext

C. Occasional PestsThese are pests for which the GEP is quite below the EIL and it touches the EIL occasionally and sporadically. Such insects may be present on a crop most years but more often than not, they do not cause economic damage e.g. armyworm, Mythimna separata and cababge butterflyD. Minor Pests These pests are the species that are recoded feeding or ovipositing on the crop plant(s) but usually do not cause damage of economic importance. Many pests listed as minor pests are potentially major pests e.g. rice butterfly . Cabbage butterflyEndPreviousNext

Agricultural Production Levels and Crop LossesEndPreviousNext

Production Levels and Crop LossesA. Potential productionPotential production is maximum possible production level of a crop variety under a given environment when there is no water, nutrient and pest stress on the crop. It is not generally possible to attain it at farmers level.B. Attainable productionAttainable production level is obtained when there is some water or nutrient stress on the crops but crop is protected against pests. Attainable production is about 50% of potential production. Healthy rice cropEndPreviousNext

C. Actual productionActual production is production level obtained by farmers when water and nutrient stress as well as pest stress prevail on the crops. This is production level achieved by farmers in the absence of any plant protection measures. Actual production constitutes only 15% of potential production and 30% of attainable production. A major chunk of attainable production is thus robbed by pests. It is imperative to avoid these losses to boost agricultural productivity.Crop damaged by pestsEndPreviousNext

Losses due to animal pests, pathogens and weeds on different crops Source: Oerke et al. (1994)EndPreviousNext

Crop Loss (%) Animal pests Pathogens Weeds Total Rice Wheat Barley Maize Potatoes Soybeans Cotton Coffee 20.7 9.3 8.8 14.5 16.1 10.4 15.4 14.9 15.1 12.4 10.1 10.9 16.3 9.0 10.5 14.8 15.6 12.3 10.6 13.1 8.9 13.0 11.8 10.3 51.4 34.0 29.4 38.4 41.3 32.4 37.7 40.0Mean 15.6 13.3 13.2 42.1

Estimates of crop losses in principal agricultural crops in different continents Source: Oerke et al. (1994)EndPreviousNext

Continent Loss (%) Animal pests Pathogens Weeds TotalAfricaNorth AmericaLatin AmericaAsiaEuropeCISOceania 16.7 10.2 14.4 18.7 10.2 12.9 10.715.69.613.514.29.815.115.2 16.6 11.4 13.4 14.2 8.3 12.9 10.348.931.241.347.128.240.936.2 Mean 15.6 13.3 13.242.1

Estimated crop losses caused by insect pests under modern agriculture in IndiaSource: Dhaliwal et al. (2004)EndPreviousNext

CropActual production during 2001-02 (million tonnes)Estimated loss in yield due to insect pestsHypothetical production in the absence of losses due to insect pests (million tonnes)Monetary value of estimated losses (million rupees)PercentTotal (million tonnes)RiceWheatMaizeOther cerealsChickpeaOther pulsesGroundnutRapessed-mustardOther oilseedsCotton (lint)*Sugarcane93.171.813.320.65.37.96.95.0*8.610.1300.125525301020153020502031.03.84.48.80.62.01.22.12.210.175.0124.175.617.729.45.99.98.17.110.820.2375.11,64,30023,56021,34042,6807,20026,40016,08027,30026,4002,87,60046,540 Total = 689400 (US$ 15,320 million)

Prevention of Crop Losses It is thus amply clear that pests are major bottleneck in the production of crops inflicting on an average about 30% yield loss amounting to monetary loss of more than Rs. 1,30, 000 crores at current value. There is thus ample scope to enhance our food production by curtailing losses due to pests. Only option to boost our production remains in growing improved crop cultivars with better pest management options. Pesticides have played a commendable role in increasing our food production and protecting us against disease vectors. However sole reliance on pesticides has created several problems.Pest monitoringTimely pesticide applicationEndPreviousNext

Integrated Pest Management In such a situation Integrated pest management (IPM) can help in effective management of pests. In IPM, different methods of pest control such as resistant varieties, cultural methods, physical methods, natural enemies and pesticides are integrated to suppress pest population without harming other components of the environment. Pesticides have definite role to play in IPM but their use has to be need-based. IPM ConceptEndPreviousNext

Lets Sum UpPests compete with man for food, fibre and shelter, transmit pathogens or otherwise threaten human health comfort or welfare. Insects are the most frequent pests. Besides, mites, ticks, nematodes, mollusks, rodents, deer, birds, and microbes also act as pests.Pests can be categorized as severe, occasional or minor depending upon their frequency and level of occurrence, and damage inflicted.Pests can cause on an average as high as 50% crop losses with serious economic implications. It thus becomes necessary to prevent these losses to boost agricultural productivity.Integrated pest management (IPM) can help in effective management of pests and prevention of yield losses.

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