Effects of the expression of foreign insect-resistant genes in cotton plants on Bemisia tabaci

The effects of expression of foreign insect-resistant genes in cotton plants on Bemisia tabaci(Gennadius) were studied.Developmental durations(from egg to adult)of B.tabaci on three different varieties of transgenic Bt cotton plants,GK12,33B and SGK,were 15.56,15.35,and 15.25 d,respectively.These were respectively 24.55%,26.23% and 18.71% shorter than those on the conventional parental cotton varieties SM3,33 and SY321.The survival rates of B.tabaci on the transgenic Bt cotton varieties GK12 and 33B were 69.16% and 73.23% respectively,which were 26.29% and 12.81% higher than those on the parental varieties of these plants SM3 and 33(54.76% and 64.91%).There was no significant difference in the survival rate of B.tabaci on the transgenic Bt cotton variety GK12(63.21%) and its parental variety SY321(62.61%).The fecundity of B.tabaci on the transgenic Bt cotton varieties GK12 and 33B was 84.00% and 77.25%,which was 34.93% and 10.35% higher than that on the parental varieties SM3(62.25%)and 33(70.00%).There was no significant difference in the fecundity of B.tabaci on SGK and SY321.The percentage of female B.tabaci on the transgenic Bt cotton plants GK12,33B and SGK was 26.71%,46.23% and 19.17% higher,respectively,to that on the parental varieties SM3,33 and SGK.These results indicate that the introduction of the foreign Bt gene promoted the development of B.tabaci and increased oviposition and the percentage of females of this pest on cotton plants.