印楝素对水稻二化螟的生物活性及控制作用

Control Effects and Biological Activity of Azadirachtin on Rice Stem Borer, Chilo suppressalis in Paddy Fields

系统地研究了印楝素对水稻二化螟的生物活性及作用方式。试验结果表明 ,印楝素乳油对二化螟有胃毒、拒食、忌避、内吸等多种作用方式。 0 .75和 0 .5 0mg/L印楝素乳油处理茭白饲喂 3龄幼虫 ,幼虫分别于 3、6d内全部死亡 ;0 .375、0 .30 0和 0 .2 5 0mg/L印楝素乳油低剂量处理茭白饲喂 3龄幼虫 ,幼虫拒食率分别达 94 .38%、88.74 %、80 .0 7% ;成虫产卵量分别下降 80 .70 %、6 2 .0 5 %、4 0 .86 %。6、3和 2mg/L印楝素乳油处理初孵蚁螟 ,2 4h内死亡率达 10 0 %。印楝素乳油对成虫产卵有显著的忌避作用。稻田喷施 0 .3%印楝素乳油 6 2 .5和 12 5mL/ 6 6 7m2 防治二化螟 ,2 1d保苗效果分别为 88.14 %和 94 .13% ,防治效果分别为 85 .36 %和 90 .76 %。表明印楝素对二化螟有较高的生物活性和理想的控制效果。

Biological activity and functional pattern of aza di rachtin on rice stem borer, Chilo suppressalis were systemati cally studied. Azadirachtin had many functional patterns against Chilo s uppressalis as stomach poison,antifeedant,deterrence,sucking toxicity. After feeding on water-oats treated with 0.75 and 0.50 mg/L of azadirachtin, the 3rd-instar larvae were completely died in 3 and 6 days, respectivel y. The antifeedant rates of the larvae reached 93.48%,88.74%,80.07%, and the num ber of eggs laid were decreased by 80.70%,62.05%,40.86% after the 3rd-instar l arvae fed on water-oats treated with 0.375, 0.300 and 0.250 mg/L of azadirac htin, respectively. Mortality of the newly-hatched Chilo suppressalis reached 100% within 24 hours after treatment with 6,3 and 2 mg/L o f azadirachtin. Azadirachtin deterred adults from laying eggs on rice plants a fter application. The effects of saving seedlings reached 88.14% and 94.13%, th e control effects reached 85.36% and 90.76% at 21 days after spraying 0.3% azadi rachtin emulsion 62.5 mL/667 m 2 and 125 mL/667 m 2 in the paddy fiel ds, respectively. It was suggested that azadirachtin had higher biological a ctivity and efficacy against Chilo suppressalis in paddy fields .