4种杀虫剂对取食朱槿的扶桑绵粉蚧的毒杀作用

Toxic effects of four insecticides on mealybug, Phenacoccus solenopsis Tinsley(Hemiptera: Pseudococcidae) fed on Hibiscus rosa-sinensis(Malvales: Malvaceae)

扶桑绵粉蚧已入侵广西,并在朱槿上成功定殖,且对朱槿造成一定的为害,研究杀虫剂对其毒杀作用,可为其大暴发时的应急防治提供参考。采用浸叶法测定了丙溴磷、毒死蜱、吡虫啉、印楝油对取食朱槿的扶桑绵粉蚧的毒杀效果,用Probit Analysis建立毒力回归方程,比较了扶桑绵粉蚧对不同杀虫剂的敏感性。结果表明,印楝油对扶桑绵粉蚧的直接毒杀作用较弱,药后3 d最高浓度(10 mL/L)对一龄若虫的致死率仅为66.43%,对其他3个虫龄几乎无直接毒杀作用;另外3种化学杀虫剂均具较强的毒杀作用,药后3 d,大多数试验浓度的校正死亡率在50.00%以上,最高浓度的死亡率均超过90.00%;不同虫龄的敏感性顺序为一龄>二龄>三龄>雌成虫,药剂的敏感性顺序为丙溴磷>吡虫啉>毒死蜱。说明化学杀虫剂对扶桑绵粉蚧的直接毒杀效果显著,但不同虫龄对不同药剂的敏感性差异较大,田间用药宜根据虫龄结构,选择合适的药剂、剂量和时机。

Phenacoccus solenopsis has invaded Guangxi and successfully colonized on Hibiscus rosa-sinensis, and it has caused some damage to H. rosa-sinensis. In order to provide references for emergency control of its outbreak, leaf dipping method was used to test the toxic effects of profenofos, chlorpyrifos, imidacloprid and neem oil on mealybug fed on H. rosa-sinensis, and toxicity regression equations were established by Probit Analysis to compare the susceptibility of different instars to different insecticides in this paper. The results showed that the direct toxic effect of neem oil against this pest was weak, after 3 days treatment, the corrected mortality rate of 1stinstar nymphs for the highest concentration（10 mL/L） was only 66.43%, and the highest concentration almost had no direct toxic effect on the other three instars.The toxic effects of the other three chemical insecticides against this pest were powerful, after 3 days treatment, the fatality rates of most doses were over 50.00%, and fatality rates of the highest concentrations were all over 90.00%. The susceptibility order of different instars was 1stinstar nymphs 2ndinstar larvae 3rdinstar larvae female adult, and the susceptibility order to insecticides was profenofos imidacloprid chl orpyrifos. It suggests that the direct toxic effects of chemical insecticides on mealybug are significant, but the differences in the sensitivity of different instars to different pesticides are obvious, so the field application should select appropriate insecticide,dose and right time based on the age structure of this pest.