苏云金杆菌对媒介蚊虫的防治研究

Efficacy of Bacillus thuringiensis serotype H-14 in controlling vector mosquitoes

目的研究苏云金杆菌对媒介蚊虫的防治效果以及菌液在室内的持效性。方法选择对媒介蚊虫具有高致病力的血清型苏云金杆菌缓释悬浮剂(B.t.H-14)防治试验区蚊虫,分别利用勺捕法和人帐诱法调查蚊幼虫和成蚊密度,与对照区蚊虫密度比较,研究B.t.H-14的现场防治效果,并在实验室观察苏云金杆菌在不同水体内的持效性。结果利用苏云金杆菌防治媒介蚊虫,在媒介蚊虫高峰季节,相关密度指数(RPI)<10,说明苏云金杆菌可以控制自然水体内媒介蚊虫的种群数量。试验区蚊虫密度维持在较低水平,幼虫密度<50条/勺,成蚊密度<20只/h,而对照区蚊虫密度随季节变化明显,幼虫密度>100条/勺,成蚊密度最高可达188只/h。在实验室内,苏云金杆菌持效期可达30 d,其中,在清水中苏云金杆菌的防治效果最好,污染水体苏云金杆菌对蚊幼虫的杀灭率在1周后达到最大值,以后逐渐降低。结论在自然环境中可利用苏云金杆菌防治媒介蚊虫,并根据蚊虫密度,施用不同浓度的菌液和确定施药次数。

Objective To study the activity and efficacy of Bacillus thuringiensis serotype H-14 （B.t. H-14） against vector mosquitoes and the persistence of bacterial liquid preparation. Methods B.t. H-14 with high pathogenicity against mosquitoes was tested in the field sites. The densities of larval and adult mosquitoes were quantified by dippingand human-baited net trapping. The results were compared with the mosquito densities in an untreated control site to determine the field efficacy of B.t. H-14. The persistence of B. thuringiensis in different water bodies was observed in the laboratory. Results The relative population index （RPI） of vector mosquitoes was under 10 during peak periods, which indicated that B.t. H-14 lowered the populations of vector mosquitoes in natural habitats. The mosquito densities in the treated site remained at a relatively low level, with a larval density less than 50/dip and an adult density less than 20/hour. However, the density of mosquitoes in the untreated control site changed considerably with seasons, with a larval density more than lO0/dip and an adult density up to 188/hour. In the laboratory, the activity of B.t. H-14 lasted 30 d. The larvicidal activity of B.t. H-14 was optimal in pure water; in polluted water, however, its activity reached the peakin one weekand then decreased gradually. Conclusion In the natural environment, B.t. H-14 can be used to control vector mosquitoes, and the concentration of bacterial liquid applied and the number of applications can be determined according to the mosquito population densities.