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

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

研究了不同温度下埃玛菌素 (emamectin)对小菜蛾Plutellaxylostella幼虫的毒力 ,并用生命表法研究了 2 5℃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 10 0 0倍左右 ,显示了埃玛菌素对该虫极高的口服毒力。 2 5℃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 14 8 3,种群趋势指数分别为 1 8和 2 7 4 ,净增殖率 (R0 )分别为3 6 6和 33 81,内禀增长力 (rm)分别为 0 0 6 6 5和 0 0 978。

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 was increased 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 (R 0) 3.66 and 33.81; and the innate capacity for increase (r m) 0.0665 and 0.0978, respectively.