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目的检测苏云金杆菌以色列亚种(Bti)对斯氏按蚊Hor株四龄幼虫的杀灭效果及作用特点,为合理使用Bti进行蚊虫防治提供参考标准和理论依据。方法首先采用Probit analysis生物测定的方法研究Bti剂量与斯氏按蚊幼虫累计死亡率的关系,通过线性回归分析获得相关公式,计算半致死浓度(LC50)等重要参数,探讨Bti对斯氏按蚊的杀伤效果。然后利用半致死浓度的Bti处理不同密度的斯氏按蚊幼虫,分析按蚊幼虫密度对Bti杀伤效果的影响。结果Bti对斯氏按蚊四龄幼虫的累计死亡率随作用时间和浓度的升高而增大,Bti的浓度对数值与累计死亡率P值呈较好的线性关系,根据所获得的公式计算出Bti作用12、24、48和72h后,半数致死浓度(LC50)分别为(1242±60)IU/L、(1112±45)IU/L、(1010±73)IU/L、(855±32)IU/L,95%致死浓度(LC95)分别为(4 170±138)IU/L、(3746±444)IU/L、(3462±409)IU/L、(3080±464)IU/L。而且随着幼虫密度的增加,其累计死亡率显著降低。结论 Bti株对斯氏按蚊四龄幼虫具有较好的杀伤效果,作用强、起效快,是一种较为理想的的灭蚊生物制剂;在Bti的使用剂量的确定上,应充分考虑蚊虫密度的因素,蚊虫密度越大所需Bti剂量应适当加大。
Objective To detect the killing effect and the action characteristics of Bacillus thuringiensis (Bti) against the fourth instar larvae of Hormones Anopheles Hor and to provide reference and theoretical basis for the rational use of Bti for mosquito control. Methods The relationship between Bti dose and cumulative mortality of Anopheles stephensi was studied by Probit analysis bioassay. Relevant formulas were obtained by linear regression analysis, and the important parameters such as LC50 were calculated. The killing effect. Then the Anopheles stephensi larvae were treated with Bti at a lethal concentration to analyze the effect of anopheline larval density on the killing effect of Bti. Results The cumulative mortality of Bti against fourth instar larvae of Anopheles stephensi increased with time and concentration, and the linear relationship between Bti concentration and cumulative mortality P value was good. Based on the obtained formula After 12, 24, 48 and 72 hours of treatment with Bti, the median lethal concentrations (LC50) were 1242 ± 60 IU / L, 1112 ± 45 IU / L, 1010 ± 73 IU / L, (3462 ± 409) IU / L, (3080 ± 464) IU / L, (3746 ± 444) IU / L, L. And with the increase of larval density, its cumulative mortality was significantly reduced. Conclusion The Bti strain has a good killing effect on the fourth instar larvae of Anopheles stephensi. It has a strong effect and fast onset of action. It is an ideal anti-mosquito biological agent. Considering the dose of Bti, mosquitoes should be fully considered The density factor, mosquito density required Bti dose should be appropriately increased.