埃玛菌素对小菜蛾幼虫的毒力及其对子代种群增长的影响

研究了不同温度下埃玛菌素（emamectin）对小菜蛾Plutella xylostella幼虫的毒力，并用生命表法研究了25℃下埃玛菌素亚致死剂量LC₃₀）处理小菜蛾3龄初期幼虫后对其子代的影响。结果表明，埃玛菌素为典型的正温度系数药剂，对小菜蛾幼虫的触杀毒力在温度16～31℃间提高了10倍左右，口服毒力在相同温度范围内提高1 000倍左右，显示了埃玛菌素对该虫极高的口服毒力。25℃下埃玛菌素亚致死剂量处理当代幼虫后，对其子代的存活和繁殖均有明显影响，处理组和对照组子代的世代存活率分别为3.7%和35.5%，平均产卵量分别为92.4和148.3，种群趋势指数分别为1.8和27.4，净增殖率（R₀）分别为3.66和33.81，内禀增长力（r_m）分别为0.0665和0.0978。

Toxicity of emamectin to the diamondback moth, Plutella xylostella, and the effects on survivors of parent generation treated with sub-lethal dosage

Toxicity of emamectin to larvae of the diamondback moth, Plutella xylostella, at different temperatures was surveyed, and the effects on survivors of parent generation treated with sub-lethal dosage of the insecticide at 25℃ were studied with life table method. The results showed that the toxicity of emamectin against the insect was increased as the temperature was enhanced in the temperature range tested: the contact toxicity of the insecticide wasincreased by about 10 fold, and the ingestion toxicity by about 1 000-fold when the temperature was enhanced from 16℃ to 31℃. Emamectin showed an extremely high ingestion toxicity. The life table was established after the insect was treated with the insecticide in sub-lethal dosage. The insecticide had some adverse effects on the survival and reproduction of the insect. The life parameters of the treated population were lower compared with the control population: the survival rate was 3.7% and 35.5% in the treated population and in the control, respectively; the fecundity 92.4 and 148.3; the index of population trend 1.8 and 27.4; the net reproductive rate (R₀) 3.66 and 33.81; and the innate capacity for increase (r_m) 0.0665 and 0.0978, respectively.