Predators and beneficial organisms to fight pests

By Our Agriculture Correspondent

ENTOMOLOGISTS HAVE devised sound and eco-friendly technologies to fight the dreaded insect pests of cotton, and we have now proved that there is no need for any chemical insecticides for controlling cotton pests. They can be easily managed through low- cost integrated pest management strategies, which environmentally sustainable and economically viable. We can now boldly say that either give holiday to chemical pesticides or give holiday to cotton cultivation,'' says Dr. S. Jayaraj, ICAR National Professor, Agricultural College and Research Institute (AC&RI), Tamil Nadu Agricultural University (TNAU), Madurai.

Highlighting a holistic approach to fight the cotton pests, Dr. Jayaraj, points out that integrated nutrition management should form part of the whole exercise. Cotton varieties with natural resistance to the pests should be selected, and acid-delinting and removal of floating seeds should be religiously practiced, according to him. The seeds should be thoroughly washed and treated with biofertilizers and biopesticides.

About five packets each of Azospirillum and Phosphobacterium; 30 g of Trichoderma viride and 75 g of Pseudomonas should be made in to a slurry and mixed with 3 kg of de-linted seeds to cover a hectare. The biofertilizer treatment enhanced the induced tolerance to pests and diseases, besides supplying nutrients and inducing drought tolerance. The seed treatment with the biopesticides ensured protection against root rot and wilt infection.

Sound water management and the use of botanical insecticides such as neem products, pungam oil, and leaf extracts of nochi (vitex negundo), Ipomea, Jatropha and Prosopis will prove to be of great advantage in keeping the pests at bay. Regular pest surveillance and community cooperation are a must for the successful implementation of IPM for cotton. Microbial pesticides such as Nuclear Polyhedrosis Virus (NPV), and Beauveria bassiana can be effectively used to manage the American bollworm and Spodoptera leaf caterpillars.

Release of Trichogramma egg parasitoids four times at weekly intervals from the onset of adult moth catches in light or pheromone traps or on sighting eggs or neonate larvae have been found to be effective in checking the population of the pests. Chrysopera and ladybird bugs are efficient predators of cotton pests, and they can be locally produced and released periodically. Some Reduviid beetles and dragonflies can be cultured in situ in the field and they help in sound pest proofing of cotton crop.

The other common predators found in the cotton ecosystem such as spiders, anthocorids and lacewing flies proliferate in the absence of chemical insecticides. Spiders, especially the jumping spiders are efficient hunter of young larval pests. In China, special heaps of twigs are provided in cotton fields to encourage the breeding of spiders, which afford sound protection against some serious enemies of the crop. In order to retain the population of natural predators, especially when the prey population dwindles, special efforts should be made to provide food for them. This is best achieved by raising pollen- or nectar-rich crops such as pearl millet, maize, castor and sunflower in a poly crop system, according to Dr. Jayaraj.

Birds such as drongo and swallows should be encouraged to visit the fields by providing suitable bird perches in the field. He has come out with several other cultural solutions and simple mechanical means to manage the cotton pests, which can be dovetailed into the cotton IPM strategy.

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