杀虫剂呋喃虫酰肼对家蚕的毒性试验

Toxicity of Pesticide Furan Tebufenozide to Silkworm

呋喃虫酰肼是具有类似蜕皮激素作用的昆虫生长调节剂类杀虫剂。为了明确呋喃虫酰肼用于大田害虫防治后对农业生态环境中家蚕安全性的影响,进行了该杀虫剂对家蚕的毒性试验。结果表明,50-1 000 mg/L呋喃虫酰肼药液对家蚕3龄幼虫无熏蒸毒性,但有一定触杀毒性和强烈的胃毒作用。采用食下毒叶法添食呋喃虫酰肼药剂,对2龄起蚕的48 h LC50值为142.095μg/L;对4龄起蚕6 h、24 h的LC50值分别为1.284 mg/L、0.274 mg/L;对5龄起蚕的6 h、24 h的LC50值分别为9.180 mg/L、1.431 mg/L。用LC10以下浓度的呋喃虫酰肼药液给3龄、4龄家蚕幼虫添食后,幼虫未出现蜕皮症状,熟蚕的上蔟时间也未改变。桑树喷洒100 mg/L呋喃虫酰肼药液至湿润,喷药后68 d时采摘桑叶连续24 h饲喂5龄起蚕仍会导致其全部中毒,头胸部出现与眠蚕相似的三角区,部分中毒幼虫的表皮剥落。由于呋喃虫酰肼对家蚕具有强烈的胃毒作用,且在桑叶中的残效期很长,因此该杀虫剂不能用于蚕区及周围的大田与森林害虫防治。

Furan tebufenozide is a pesticide of insect growth regulator type with activity similar to ecdysone. To ascertain the impact of furan tebufenozide on the security of silkworm （ Bombyx mori） with its application in farm land for pest control, we determined the toxicity of this pesticide to silkworm. Our study indicated that application of this pesticide with concentration of 50-1 000 mg/L on the 3rd instar larvae had no fumigation toxicity, but had a certain contact toxicity and strong stomach poison effect. LCso of the pesticide to the 2rd instar newly exuviated larvae at 48 h was 142. 095μg/L as shown by feeding the larvae with mulberry leaf treated with the pesticide. LCso of the 4th instar larvae was 1. 284 mg/L and 0. 274 mg/L at 6 h and 24 h, respectively, and that of the 5th instar larvae was 9. 180 mg/L and 1. 431 mg/L at 6 h and 24 h, respectively. After feeding the 3rd and 4th instar larvae with mulberry leaf treated with the pesticide under LClo concentration, no molting of silkworm larvae was observed, and no influence on the mounting time of mature larvae was observed, either. Feeding the 5th instar newly exuviated larvae with mulberry leaves harvested at 68 d post spraying of 100 mg/L pesticide continuously within 24 hours could still lead to poisoning of all the larvae. Cephalothoracic part of the poisoned larva showed triangular form similar to that shown in molting larva and integument of some poisoned larvae came off. This study indicates that furan tebufeno- zide cannot be used for controlling agriculture and forest pests in silkworm rearing and surrounding areas for its strong stomach toxicity to silkworm larvae and long residual period in mulberry leaf.