Effect of tebufenozide on growth and fecundity of the selected strain of Spodoptera exigua

Effect of tebufenozide on growth and fecundity of the selected strain of Spodoptera exigua (Hubner) were studied. The results showed that the hatching IC_ 50 of SS and RR strains was 179.38 and 160.71 mg/kg, respectively, and larval survival IC_ 50 was 18.64 and 30.53 mg/kg, respectively. The influence of tebufenozide on egg hatching rate was less, while that on the larval survival rate was greater. After newly emerged larvae (1st instar) were treated with tebufenozide in 6 days, the larval survival rate and pupation rate decreased with the increasing of tebufenozide. The larva developmental duration increased 2.71 and 6.19 d respectively, when treated with highest and lowest of tebufenozide. Treated with same concentration, it decreased 0.94～2.59 d in RR strain than that in SS strain. When the 3rd instar larvae were treated with tebufenozide for 12 h in the two strains, the pupation rate and the average pupa weight decreased with the increasing of tebufenozide. The proportion of female pupae varied slightly, in which it was below 50% in SS strain while above 50% in RR strain. The emergence rate tended to decrease and the influence was greater when the treatment concentration was higher than 1.00 mg/kg.