安徽西南部家蚕白僵病病源及传播途径追踪

 【目的】明确安徽西南部家蚕白僵病菌株来源和传播途径,控制蚕病流行。【方法】利用ISSR分子标记对安徽西南潜山的病蚕、蚕室及其周边桑园、农田及松林的70株球孢白僵菌进行聚类分析和三维主坐标分析。【结果】该地区的球孢白僵菌为优势性明显的异质种群;6个类群中仅主病源第II-1类群和次病源第IV类群引起家蚕的地方性白僵病,与用于防治松毛虫的菌株及在附近松毛虫种群中自然流行的土著菌株关系较远。生物测定表明,使用松毛虫分离株使家蚕死亡25%的LC25、LD25和LT25分别为使用家蚕分离株使家蚕死亡75%的LC75、LD75和LT75的1 327、1 378和1.5倍。【结论】鉴于松毛虫分离株明显的寄主专化性,在该蚕区使用由这类菌株研制的白僵菌杀虫剂防治松毛虫对蚕业是相对较为安全的。另外,当年夏秋季蚕室附近螳螂种群的白僵病大流行与家蚕白僵病无关。

Tracing of the Origin and the Spreading Track of Silkworm White Muscardine in Southwestern Anhui

【Objective】To understand and define the pathogen origin and spreading track of white muscardine caused by entomopathogenic fungus Beauveria bassiana in southwestern Anhui and to control prevalence of silk disease.【Method】Seventy isolates of B. bassiana from silkworm cadavers, rearing room and soil from surrounding mulberry garden, cropland, and adjacent pine plantations were tested for clustering and 3-d principal coordinate analyses with the ISSR data.【Result】The local B. bassiana population is heterogenous, with obvious dominance. Among the 6 groups, only group II-1 (the primary disease origin) and group IV (the secondary origin) caused enzootic muscardine, while both of them were neither related to the isolate used as fungal insecticide applied against the masson pine caterpillar nor to the indigenous isolates prevailing in pine caterpillar population. A bioassay revealed that LC25, LD25 and LT25 caused by the strain isolated from infected pine caterpillars were 1 327, 1 378, and 1.5 times of LC75, LD75 and LT75 caused by a typical pathogenic strain isolated from silkworm, respectively. 【Conclusion】 Based on obvious host specificity of the isolates from the pine caterpillars, the use of B. bassiana insecticide developed from these isolates against the pine caterpillars is comparatively safe to sericulture. The epizootic caused by B. bassiana in surrounding mantid populations is not associated to the white muscardine of silkworms.