The Role of Biological Control for Organic Cotton Production in Egypt

Professor of Environmental Protection, Director of Biological Control Center, Faculty of Agriculture, Cairo University, Egypt

Abstract
Energy flows in most food chains in the agroecosystem are crowned with beneficial natural enemies including different species of predatory and parasitic insects. They are utilized in organic and IPM cotton production to replace the conventional insecticides usually applied for insect pest's control. Natural populations of 6 coccinellid and 5 staphylinid, 2 carabid, (Coleoptera); 3 anthocorid, 3 reduviid (Heteroptera), 5 syrphid (Diptera); 2 chrysopid (Neuroptera), 1 thripid species (Thysanoptera) and 3 labidurid (Dermaptera) species were manipulated in Egyptian clover to aggregate in seed production stripes (stripe technique) adjacent to and across the planed cotton fields during April/May. These 30 predatory species prey on the main insect pests attacking cotton during vegetative growth stage beginning from April/May, i.e., tetranychid mites, aphids, thrips, white flies (eggs, nymphs & pupae) and the cotton leaf worm (egg masses, newly hatched larvae & Pupae). High populations of these predators develop on different pests in clover grown as forage crop along the season where no insecticide applications occur. Their adults aggregate in the flowering clover stripes left for seed production feeding mostly on nectar, pollens and remaining pests. By dryness of the clover stripes supported by the law preventing clover irrigation after the 10th of May, populations of all these predatory species abandon the clover, migrating side wards into the adjacent cotton fields. Thus, they get their energy for developing in their food chains by devouring all individual stages of the previously mentioned insect pests present on cotton plants (102 food chains); showing an excellent high protection against cotton pests suppressing their populations under the level of economic threshold damage during vegetative growth stage.

Starting cotton flowering in June/July, pheromone traps were used to detect the first appearance of the cotton bollworms, i.e., the pink bollworm Pectinophora gossypiella (Saunders) and the spiny bollworm Earias insulana (Boisd.). The commercially (Tricholip) produced egg parasitoid (Trichogramma evanescens) was released anthropogenic for augmentation in the cotton field (40 card/feddan; ca 2000 eggs/card) to guide the energy flow in favor of the parasitoid by getting it from egg contents of these two pests. Accordingly, 6 successive releases (10-days intervals) of T.evanescens gave high protection to cotton bolls. Infestation with boll worms remained by zero% during July, while it was 8 – 10% in the traditional cotton fields to start applications with insecticides.

In conclusion, better understanding to biodiversity of natural enemies as biocontrol agents and the routes of energy flow among the complex net of food chains governing the biodynamics in the Egyptian agroecosystem, enabled us to develop such strategy to abandon application of the conventional insecticides in both IPM and organic cotton production in Egypt; an approach contributing to improvement of the agroecosystem and production of organic healthy crops.