12种杀虫剂对草地贪夜蛾和霍氏啮小蜂的选择毒力

Selective toxicity of twelve insecticides to Spodoptera frugiperda and Tetrastichus howardi(Olliff)

  • 摘要: 【目的】评价12种杀虫剂对草地贪夜蛾(Spodoptera frugiperda)及其天敌霍氏啮小蜂(Tetrastichus howardi)的毒力和选择性,为协调草地贪夜蛾的化学防治和生物防治提供科学依据。【方法】通过玉米叶片浸渍法和试管药膜法,分别测定40%杀虫双、94%溴氰虫酰胺、98%噻虫嗪、94%茚虫威及金龟子绿僵菌(Metarhizium anisopliae)等12种杀虫剂对草地贪夜蛾2龄幼虫和霍氏啮小蜂成蜂的选择毒力,明确草地贪夜蛾和霍氏啮小蜂对常用杀虫剂的敏感性。【结果】在11种化学杀虫剂中,95%甲氨基阿维菌素苯甲酸盐对草地贪夜蛾2龄幼虫的毒力最强,24 h的半数致死浓度(LC50)为0.42 mg/L,98%噻虫嗪的毒力最弱(24 h-LC50为13.56 mg/L);95%甲氨基阿维菌素苯甲酸盐对霍氏啮小蜂成蜂的毒力也最强(24 h-LC50为0.09 mg/L),94%茚虫威的毒力最弱(24 h-LC50为4.45 mg/L)。11种化学杀虫剂的选择毒力指数(STR)排序为:94%茚虫威 > 96%氟苯虫酰胺 > 95%虫螨腈 > 95.3%氯虫苯甲酰胺 > 95%甲氨基阿维菌素苯甲酸盐 > 98%虱螨脲≈98%噻虫嗪 > 94%溴氰虫酰胺 > 81.2%乙基多杀菌素≈40%杀虫双 > 95%四氯虫酰胺,表明94%茚虫威在有效防治草地贪夜蛾的前提下对霍氏啮小蜂的保护性最强。金龟子绿僵菌对草地贪夜蛾和霍氏啮小蜂的LC50和STR随时间的推移呈明显下降趋势,均在第4 d达最大值、第6 d为最小值,说明微生物杀虫剂发挥药效存在一个滞后过程。【结论】95%甲氨基阿维菌素苯甲酸盐的毒力最大,可作为防控草地贪夜蛾应急施药首选;金龟子绿僵菌和94%茚虫威的选择性大,可作为草地贪夜蛾综合防控的推荐用药;94%溴氰虫酰胺和98%噻虫嗪的毒力较小,不适宜用于草地贪夜蛾的化学防治。

     

    Abstract: 【Objective】To provide the scientific evidence for the coordination of the chemical and biological control of Spodoptera frugiperda, this paper evaluated the toxicity and selectivity of twelve insecticides to S. frugiperda and its natural enemy Tetrastichus howardi.【Method】The corn leaf dipping method and residual film method were used to evaluate the selective toxicity of the 12 insecticides including 40% bisultap, 94% cyantraniliprole, 98% thiamethoxam, 94% indoxacarb, and Metarhizium anisopliae to the second instar larvae of S. Frugiperda and the adults T. howardi, to clarify the sensitivity of S. frugiperda and T. howardi tothe commonly used insecticides.【Result】Among the 11 chemical insecticides, 95% emamectin benzoate had the highest toxicity to the second larvae of S. frugiperda and the median lethal concentration(LC50) 50 for 24 hours was 0.42 mg/L. While 98% thiamethoxam had the lowest toxicity(24 h-LC50 was 13.56 mg/L). 95% emamectin benzoate also had the highest toxicity to the adult T. howardi(24 h-LC50 was 0.09 mg/L). 94% indoxacarb had the lowest toxicity(24 h-LC50 was 4.45 mg/L). The order of the selective toxicity ratio(STR) of the 11 chemical insecticides was as follow:94% indoxacarb > 96% flubendiamide > 95% chlorfenapyr > 95.3% chlorantraniliprole > 95% emamectin benzoate > 98% lufenuron≈98% thiamethoxam > 94% cyantraniliprole > 81.2% spinetoram≈40% bisultap > 95% tetrachlorantraniliprole. This order suggested 94% indoxacarb had the strongest protective effect on T. howardi on the premise of controlling S. frugiperda. The LC50 and STR of metarhizium anisopliae against S. frugiperda and T. howardi presented the tendency of decrease with time passing by, reaching the maximum on the 4th day, and the minimum on the 6th day, which suggested that there was a lag process before the biological insecticides displayed their efficacy.【Conclusion】95% emamectin benzoate has the highest toxicity, and thus it can be the first choice to emergently control S. frugiperda;M. anisopliae and 94% indoxacarb have the highest selectivity, and thus can be recommended as the drug which can comprehensively control S. frugiperda;94% cyantraniliprole and 98% thiamethoxam have the lowest toxicity, and therefore they are not fit for the chemical control of S. frugiperda..

     

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