Effects of spirotetramat on Tetranychus viennensis population

【Objective】To evaluate the effects of spirotetramat on Tetranychus viennensis.【Methods】We in-vestigated the lethal effects of spirotetramat against the adult of Tetranychus viennensis using leaf-dip bio-assay method under laboratory condition. A time- dose mortality model(TDM) was established,whichpassed the Hosmer-Lemeshow test. On this basis,the sublethal effects of spirotetramat on female adult T.viennesis was investigated.【Results】The peak mortality of the female adults was found at 24 h after treat-ed with spirotetramat. The values of the LC50 at 24,48,72 h after treated with spirotetramat were 294.58,254.70,172.61 mg·L-1,and the median lethal time( LT50) of spirotetramat was 62.63 h at the concentra-tion of 200 mg·L- 1. The survival rates of the female adults treated by two sublethal concentrations(200mg·L-1and 20 mg·L-1) of spirotetramat fell to 20% and 37.5% at 9-10 d,respectively. The fecundity perfemale and the egg hatching rate declined sharply with the spirotetramat concentration increased. Com-pared with the control group,the gross fecundity and net fertility of female adult T. viennesis at the dose of200 and 20 mg·L-1significantly reduced respectively 44.11%,38.00% and 82.79%,64.70% but the grossfecundity and net fertility increased respectively 1.73% and 3.96% at the dose of 0.02 mg·L-1. The surviv-al rate of F1 generation was not significantly different with the control.【Conclusion】Spirotetramat can re-duce the population of Tetranychus viennensis.