Department of Biocontrol - An Overview

Department of Biocontrol is a distinct wing of the company carrying out applied research on biological control of insect pests.

Biological Control of Pests

Agriculture farming, one of the important sectors of our economy is facing hurdles in successful crop production due to infestation of insect pest, plant pathogens, weeds and mites. Biological control is a strategy of reducing pest population using predators, parasitoid or pathogens with active involvement of human role. It involves rearing of beneficial organisms in the laboratory and releasing of natural enemies of pests in the cultivated field. These beneficial natural enemies are preferentially used, as they do not seem to cause any harmful effect on humans and the environment. Biocontrol is a valuable component in the integrated pest management (IPM) in terms of decreasing the reliance of agriculture on chemical pesticides. Advantages of utilizing natural enemies are that, some of them reproduce rapidly, some go in search of pest and some of them can survive even at low pest density. Beneficial insect group belonging to parasitoids, predators and pathogens are the future potential for biocontrol. Diversified groups of predators and parasitoids play significant roles in pest management. Even though they would not completely eliminate the need for insecticides, they will reduce the reliance upon them.

Common parasitoids include wasps and flies. One of the beneficial parasitoids, Trichogramma polyphagous stingless wasp, parasitizes eggs of most of the Lepidopteron pests (moths). Predators include beetles, flies, mites, bugs, wasps and spiders. Ladybird beetles are beneficial as they eat large quantities of aphids, mites and other arthropods that feed on various plants. Bacterial pathogen, Bacillus thuringiensis targets caterpillars. Fungi like Beauveria bassiana attack whitefly, aphids, thrips, grasshoppers and locusts. The activity of Nuclear Polymorphic Virus (NPV) has been recorded against H. armigera, S.litura, S. exigua, A. moorei, A. ipsilon and A. segetum, and protozoans such as microsporidians. These are promising entomopathogens.

Biological control is used in three ways- (i) Classical method, (ii) Augmentation and (iii) Conservation.

Classical method involves importation and introduction of new natural enemies into target area against foreign pest for re-establishment of balance between pest and natural enemies. Here they get permanently established and provide long-term suppression of target pest. Orthogalumna terebrantis (Acari:Orthogalumnidae) imported from Argentina via USA, 1982/1986, released for the control of water hyacinth in 1986 in Bangalore, Karnataka and later in Kerala, has established in all released sites and is spreading on its own.

Augmentation being the periodical introduction of natural enemies to achieve pest control, does not establish and need to be introduced each time when pest populations reach the threshold level. Large number of natural enemies are released for instant reduction of pest population which are called as inundative releases. The expected outcome is immediate pest control. Trichogramma species are the most commonly used insects in inundative augmentative control in the world. Sometimes, small number of natural enemies will be released at specified intervals, when pest population is low throughout the pest periods. This is called inoculative release. The introduced predators or parasitoids reproduce and their progeny are expected to provide pest control. The expected outcome here is to keep the pest number low and never allow them to reach economic threshold. Release of lady beetle (Cryptolaemus montrouzieri) in spring to control mealy bugs is an example of inoculative release.

Conservation is a strategy of protecting the already existing natural enemies. Conservation activities include limited use of chemical insecticide to avoid killing of natural enemies, increasing the availability of alternative host or prey by providing sources of water, food (insect pests, pollen or nectar) and shelter (tress, shrub or herbaceous plants). Diadegma insulare is the most important parasitoid wasp of the diamondback moth (DBM), parasitizing more than 75% of its larvae. D. insulare pupates inside the cocoon made by the DBM larva. They not only parasitize DBM larvae but also make them consume lesser food than non-parasitoid larvae. In field, D. insulare populations are conserved by monitoring limited use of insecticides where density of wasps are high and with use of plants with nectar source.

Advantages of Using Biocontrol Agents

• Occur naturally
• Eco-friendly
• Cost effective
• Huge host specificity
• Safe to handle
• Harmless non-target species