苏云金芽胞杆菌MB-15可湿性粉剂增效因子的筛选

目的]筛选对苏云金芽胞杆菌(Bacillus thuringiensis,简称Bt)MB-15可湿性粉剂具有最佳增效作用的物质,并对增效作用显著的混配组合进行了增效作用的评定。方法]以小菜蛾为生物测定昆虫,采用浸叶法测定了6种添加物对苏云金杆菌MB-15可湿性粉剂的毒杀增效作用。结果]研究发现0.1%ZnCl2、0.5%ZnCl2、1.0%ZnCl2、1.0%MgCl2、0.5%硼酸、1.0%硼酸、0.5%柠檬酸和1.0%柠檬酸对Bt MB-15可湿性粉剂表现出增效作用,其中0.5%硼酸对Bt MB-15可湿性粉剂的增效作用最强,增效比为17.2,1.0%ZnCl2次之,增效比为15.6。同时,杀虫速度的测定结果显示,0.5%硼酸的加入使Bt MB-15可湿性粉剂的致死中时缩短了约10 h,加快了Bt的杀虫速度。此外,当将1.0%ZnCl2和0.5%硼酸分别与Bt MB-15可湿性粉剂溶液室温下混合放置15 d后,两种混合物的毒力均没有明显的变化。结论]硼酸作为Bt MB-15可湿性粉剂的增效因子,不但有利于增强Bt制剂的杀虫效果而且还可以提高其杀虫速度,从而在一定程度上克服了Bt制剂杀虫效果差和杀虫速度慢等实际问题。

Screening on Synergist of Bacillus thuringiensis Wettable Powder

Objective] This study aimed to screen the best synergistic material for wettable powder of Bt MB-15 and evaluate their synergistic effect.Method] The synergism of six different kinds of additives for wettable powder of Bt MB-15 on the 2nd instar larvae of Plutella xylostella was determined by method of leaf dipping in laboratory.Result] The mixtures of Bt with 0.1% ZnCl2,0.5% ZnCl2,1.0% ZnCl2,1.0% MgCl2,0.5% boric acid,1.0% boric acid,0.5% citric acid and 1.0% citric acid all exhibited synergistic effect,in which synergistic effect of 0.5% boric acid was the highest with 17.2 synergistic ratio,followed by 1.0% ZnCl2 with 15.6 synergistic ratio.Moreover,addition of 0.5% boric acid could shorten the median lethal time of wettable powder of Bt MB-15 by about 10 h.After the mixtures of Bt with 0.5% boracic acid or 1.0% ZnCl2 was stored for 15 d at room temperature,the toxicities of two mixtures did not change significantly.Conclusion] Boracic acid as the synergist of wettable powder of Bt MB-15,not only could accelerate insecticidal effect of Bt,but also increase its insecticidal rate.So,boracic acid overcomes the disadvantages of wettable powder of Bt MB-15 such as poor insecticidal effect and slow insecticidal speed in a certain degree.