Application of Def for defoliation of cotton in the field had little effects on the eggs, second and older instar nymphs of silverleaf whitefly, Bemisia argentifolii Bellows & Perring. However, application of Def significant reduced the survival rate (30%) of first instar nymphs compared with untreated control (70%). Def, in combination with two insecticides, Karate (a pyrethroid) and Guthion (an organophosphate) also decreased the survival rates of first, second and third instar nymphs. Almost all chemical treatments did not significantly affect the survival rate of fourth instar nymphs and pupae compared with untreated control. Although numbers of
B. argentifolii adults caught on yellow sticky cards varied greatly among treatments on different dates, the differences were generally not significant. However, numbers of parasitoids, Eretmocerus spp. and Encarsia spp., caught on yellow sticky cards were significantly fewer in the plots treated with Def, Def+Guthion and Def+Karate and in untreated control than those in the plots treated with Karate and Guthion alone.