3种药剂对稻纵卷叶螟和二化螟不同龄期幼虫的毒效及抑制取食作用

Toxicity and feeding inhibition effect of three insecticides on rice leaf folder larvae(Cnaphalocrocis medinalis Guenee) and rice borer larvae(Chilo suppressalis Walker)

【目的】了解氯虫苯甲酰胺、氟虫双酰胺、氯虫·噻虫嗪复配剂等3种药剂对稻纵卷叶螟和二化螟不同龄期幼虫的控制作用,为其合理使用提供科学依据。【方法】采用Potter喷雾法测定氯虫苯甲酰胺、氟虫双酰胺、氯虫·噻虫嗪复配剂对稻纵卷叶螟和二化螟1-4龄幼虫的毒力,并测定其受药后停止取食所需时间。【结果】3种药剂对稻纵卷叶螟低龄幼虫（1-2龄）的毒力高低依次为：氟虫双酰胺〉氯虫苯甲酰胺〉氯虫·噻虫嗪,相对毒力差为1.55-1.83倍;对稻纵卷叶螟高龄幼虫（4龄）的毒力,氯虫·噻虫嗪和氯虫苯甲酰胺为氟虫双酰胺的2.04-2.32倍;3种药剂对二化螟幼虫的毒力相差不明显。3种药剂对两种害虫不同龄期幼虫的毒力相差很大,1龄与4龄幼虫相差3.20-13.62倍。用3种药剂的LC50浓度处理不同龄期幼虫,对抑制稻纵卷叶螟取食的起效时间为1-4 h,对二化螟为4-16 h,随幼虫龄期增加,起效时间延长。【结论】3种供试药剂用于防治稻纵卷叶螟和二化螟时在低龄幼虫期施药效果较好;防治低龄幼虫可优先选用氟虫双酰胺,防治高龄幼虫可优先选择氯虫·噻虫嗪混剂。

【Objective 】The study aimed at assessing the management of three presently used pesticides chlo-rantraniliprole, flubendiamide and chlorantraniliprole thiamethoxam, against leaf folder larvae（Cnaphalocrocis medinalis Guenee） and striped rice borer larvae（Chilo suppressalis Walker） to provide scientific basis for the rational use. 【Method 】Potter Tower Method was used to estimate the susceptibility and inhibited feeding of 1-4-day-old C. medinalis and C. uppressalis against these commonly used insecticides. 【 Result 】 The order of the toxicities against rice leaf folder（Instar I and II） was： flubendiamide 〉chlorantraniliprole〉 chlorantraniliprole thiamethoxam, varying in the multiple of 1.55-1.83. The toxicities of chlorantraniliprole thiamethoxam and chlorantraniliprole against C. medinalis（InstarⅣ） were 2.04-2.32 times as high as that of flubendiamide. The toxicity differences among the three pesticides against rice borer larvae were not significant. There were obvious differences in three pesticides against different stages of the two pests. The toxicity of Instar I and Instar Ⅳ differed by a factor of 3.20-13.62. All the three pesticides inhibited larval feeding when treated by concentrated LC50 where the onset time of C. medinalis was 1-4 h and while for C. suppressalis was 4-16 h. The onset time of three pesticides was prolonged with increased instar age. 【Conclusion 】These three pesticides are relatively efficient against C. medinalis and C. uppressalis in their young larva stage.Flubendiamide is preferred in the management of young larva, while chlorantraniliprole thiamethoxam is preferred in the old larva management.