Abstract: 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.

Key words: Plutella xylostella, emamectin, temperature effect, sublethal dosage, life table, population trend