Evaluation of Ten Insecticides Distributed into Seven Sequences against Bollworms Complex

Document Type : Original Article

Author

Plant Protection Station, PPI, ARC, Alexandria, Egypt.

Abstract

Ten insecticides namely chlorpyrifos, profenofos (organophosphates), alpha-cypermthrin, deltamethrin , lambda-cyhalothrin, cypermthrin, (synthetic pyrethroids), acetamiprid (neonicotinoids), emmamectin benzoate (avermectains), chlorfenapyr (halogenated pyrroles) and spinosad (bio- insecticides)] were evaluated against cotton  bollworms, the pink bollworm (PBW) Pectinophora gossypiella (Saunders), the spiny bollworm (SBW) Earias insulana (Boisd.) and the American bollworm (ABW) Heliothis armigera (Hübner) in seven sequences in 2011 cotton growing season. The average infestation number in all experimental plots was monitored before spraying and weekly for eight weeks post insecticide sequences applications. Data show that, the infestation number prespray varied between 3 to 11 infested green bolls /100 bolls. The general means of the infestation number post treatment showed significant differences between treatments with values of 3.4, 4, 4.3, 3, 4.9, 7.4, 1.6 and 24.5 infested green bolls /100 bolls for sequences from 1 to 7 and control, respectively. Reduction percentages in the infestation were determined weekly for eight weeks through the four successive sprays with 15 days interval. Based on general reduction average it is clear that all sequence programs induced high effect representing 80.0 up to 94.6%. In the same manner, the tested sequences showed high protection for the green bolls with protection percentages ranged from 69.9% (sequence 6) to 93.5% (sequence 7). On the other hand, the tested sequences reduced the cotton yield loss in comparing with the control and the recorded yield loss percentages were 10.17, 13.7, 7.91, 14.38, 20.5, 13.82 and 6.72% for sequences 1 to 7, while it was 46.76% for the control.