EFFECT OF EGG TREATMENT BY SUBLETHAL CONCENTRATION OF SOME CHEMICAL AND MICROBIAL INSECTICIDES ON BIOLOGY OF Phthorimaea operculella (Zell.), GELECHIIDAE, LEPIDOPTERA

Abstract

The results of egg treatment by sub lethal concentration of Bacillus thuringiensis strains and their mixtures and chemical insecticides Fastac, Medamec, Runner, showed a different effect on biology of Phthorimaea operculella (Zell). Eggs hatchability reached zero percent when treated with the B.t. alesti strain alone and its mixtures with B.t. kurstaki. Eggs treatment also led to the depression of pupation percentage and adult eclosion percentage from pupae. The results of treating eggs by chemical insecticides showed a superior effect of Runner in reducing eggs hatchability, in comparison with Medamec and Fastac and control treatment and the average eggs hatching percentage reached 28.7, 31.7, 45.3 and 43.6% respectively, while eggs treatment by chemical insecticides had no clear effect on larval, pupal and adult stage of potato tuber moth.