大田常用农药对家蚕的熏蒸毒性测试

为减少粮桑混栽地区大田使用农药不当对蚕桑生产造成的损失,采用密闭熏蒸法测定了7种大田常用农药对家蚕的熏蒸毒性。在30℃环境中经过24 h,对2龄起蚕的LC50:敌敌畏0.1860 mg/m3,敌畏.毒1.3241 mg/m3,毒死蜱48.4111 mg/m3,氟腈.唑磷139.8818 mg/m3,三唑磷161.1514 mg/m3,氟虫腈208.330 mg/m3,吡虫啉333.330mg/m3时2龄起蚕仍无中毒症状。在25℃下经过24 h,对2龄起蚕的LC50:敌敌畏0.2020 mg/m3,敌畏.毒3.7282mg/m3,毒死蜱91.3669 mg/m3。结果表明:农药对家蚕的熏蒸毒性随着温度的升高而增强;敌敌畏、敌畏.毒对家蚕的熏蒸毒性最强,毒死蜱有一定的熏蒸毒性,三唑磷、氟腈.唑磷、氟虫腈、吡虫啉对家蚕的熏蒸毒性较小。

Fumigating Toxicity of Insecticides Commonly Used in Rice Fields to Silkworm, Bombyx mori

Fumigating toxicities of 7 insecticides commonly used in rice fields were tested by the method of airtight fumigation against silkworm,Bombyx mori so as to reduce the risk of poor cocoon production due to the improper spray of insecticides in grain-mulborry mix-growing areas.Results showed that the LC50s of these insecticides against second instar sillkwrom larvae were 0.186 0 mg/m3(dichlorvos),1.324 1 mg/m3(10% chlorpyrifos+ 25% dichlorvos),48.411 1 mg/m3(chlorpyrifos),139.881 8 mg/m3(1%fipronil+30%triazophos),161.151 4 mg/m3(triazophos),and 208.33 mg/m 3(fipronil),respectively, but no toxic symptom appeared even when the concentration was up to 333.33 mg/m3 of imidacloprid under 30 ℃ for 24 h.However,the LC50s were 0.202 0 mg/m3(dichlorvos),3.728 2 mg/m3(10% chlorpyrifos+ 25% dichlorvos) and 91.366 9 mg/m3(chlorpyrifos) respectively under 25 ℃ for 24 h.Resultes indicated the fumigating toxicities of the tested insecticides were enhanced as the temperature increased.Dichlorvos and 10% chlorpyrifos + 25% dichlorvos showed the highest fumigating toxicity to silkworm,Bombyx mori,chlorpyrifos showed media toxicity while 1% fipronil + 30% triazophos,triazophos,fipronil,and imidacloprid extremely low.