植物杀虫剂印楝素对家蚕的毒性测定及解毒方法

测定了植物杀虫剂印楝素(azadirachtin)对家蚕的食下、熏蒸、内吸毒性及安全间隔时间:印楝素对3龄起蚕的致死中浓度(LC50)为202.67×10-6mg/L,致死中量(LD50)为12.56×10-10mg/头,家蚕对印楝素极敏感,但中毒后至死亡的时间较长,一般需3~5d;印楝素在田间常规使用浓度下对家蚕基本无熏蒸毒性;0.5%印楝素乳油2000倍稀释液根灌、喷叶处理,通过桑根或桑叶内吸并在树体内传导的作用极小,即未喷洒到药液的桑叶对家蚕相对安全;印楝素对家蚕的安全间隔时间很长,饲喂0.5%印楝素乳油800、1200、1800和2700倍稀释液处理后的桑叶,间隔30d对3龄蚕的死亡率均在50%以上。蚕用消毒剂消力威(三氯异氰尿酸、碳酸氢钠粉)1000倍和500倍溶液浸渍受印楝素污染的桑叶30min有良好的解毒作用。

Toxicity Determination of Azadirachtin to Silkworm and Detoxification Method

Toxicity of feeding, fumigation, and systemic drug of azadirachtin, one kind of phyto-pesticides, to the silkworm (Bombyx mori) were determined, as well as its poisoning symptoms and security interval in this paper. The results indicated that the median lethal concentration (LC50) was 202.67×10-6 mg / L and median lethal dose (LD50)was 12.56×10-10 mg / larva for newly molted silkworm of the 3rd instar. The silkworm was extremely sensitive to azadirachtin, but the duration of death was longer, that was usually 3～5 days. Azadirachtin concentration used routinely in the fields had no fumigation toxicity to the silkworm. By means of root irrigation or spraying lower leaf with 0.5% azadirachtin EC 2 000 times dilution solution, we found that azadirachtin seldom transmited in the mulberry tree, thus mulberry leaves not sprayed directly were relatively safe to silkworm. Security interval of azadirachtin to silkworm was long. Mortality rates of 3rd instar silkworm feeding the mulberry leaves treated with 0.5% azadirachtin EC 800, 1 200, 1 800 and 2 700 times dilute solution with 30 days interval were more than 50%. Using 1 000 and 500 times solution of disinfectant "Xiaoliwei"(Trichloroisocyanuric acid and sodium bicarbonate powder)to impregnate mulberry leaves polluted with azadirachtin for 30 minutes was a good detoxification method.