RESISTANCE LEVELS OF SOME DIFFERENT FIELD STRAINS OF THE COTTON LEAFWORM, Spodoptera littoralis (BOISD.) AGAINST CERTAIN CONVENTIONAL INSECTICIDES AND IGR’S

Four field strains of the cotton leafworm, spodoptera littoralis (boisd.) were collected from different egyptian governorates (fayoum, menofia, sharkia and dakahlia) in 2012 cotton season for monitoring their resistance to four conventional insecticides namely dursban, telton, lannate and sumi-alpha and three insect growth regulators (igrs), namely consult, cascade and tobron. in case of conventional insecticides, the results indicated that in all field strains, resistance ratios of sumi-alpha were very high followed by dursban and lannate while telton showed lower levels of resistance when compared with the other tested compounds where resistance ratios ranged between 40-55-fold, 25-38-fold, 16-38-fold and 12-18-fold, respectively. in case of igrs, resistance ratios of cascade were high where resistance ratios ranged between11-22-fold, while tobron and consult showed lower levels of resistance where resistance ratios ranged between 2-4-fold, and 4-6-fold, respectively. these results indicate the possibility of using these materials as a replacement to conventional insecticides or as alternatives in ipm programs.