INFLUENCE OF SOME INSECTICIDE SEQUENCES ON NATURAL AND ARTIFICIAL INFESTATION WITH PINK BOLLWORM PECTINOPHORA GOSSYPIELLA (SAUND.)

Trials were carried out during 1996 cotton season at Sakha Agricultural Research Station Farm to evaluate the efficiency of some in‌secticide sequences against pink bollworm larvae and to determine if the recommended interval (14 days) between two sprays for organophos‌phorus or pyrethroid is enough for insecticides to give good control or not by using the recommended and half of the recommended dosage. The percentage reductions of natural pink bollorm infestation for the different sequences ranged between 44.77 - 60.78% and 38.26‌60.19% for both recommended and half of recommended dosage, re‌spectively at two-week intervals. In the case of using the recommended dosage, all treatments re‌duced the percentage of artificial pink bollworm infestation. The se‌quence Cutabron, Kendo, Dursban induced the highest reduction, while the sequence Kendo-Cutabron-Dursban came in the lowest order. In case of half of recommended dosage, the artificial infestation for sequence (Dursban, Kendo, Cutabron) induced a high reduction (54.19%). Cutabron and Dursban were highly effective when used at the beginning. In artificial infestation, larval mortality decreased with increasing the period after spraying. In case of using the recommended dosage, all insecticides gave less than 60% after 10 days post treatment for the 1st and 2nd sprays. Kendo insecticide resulted in larval mortality less than 60% after 7 days post treatment in the 1st spray but it showed the highest mortality in the 3rd spray.