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从蝗虫自然病死虫尸中分离到一株病原菌HR_3,其纯培养物的致病性被科赫原理证明。为确定该菌在分类学上的地位 ,经生理生化测定和分子鉴定 ,此病原菌为粘质沙雷氏菌 (Serratiamarcescens)。通过口服感染测定了该菌对蝗虫的毒力 ,毒力回归方程为y =1 .0 6 7+0 . 80 9x ,致死中浓度LC50 =1 .16 4× 10 .8cfu mL。为探讨HR_3对蝗虫致病的作用机理 ,对HR_3感染蝗虫后的组织病理进行了研究 ,结果表明感染初期蝗虫的中肠上皮细胞受到破坏 ,继而出现局部变性坏死。感染 4 8h后 ,消化细胞层大部分区域被空泡状物充盈。
A pathogen, HR_3, was isolated from dead insects of natural locusts and the pathogenicity of pure cultures was proved by Koch’s principle. In order to confirm its taxonomic status, the pathogen is Serratia marcescens through physiological and biochemical assays and molecular identification. The virulence of this bacterium to locusts was determined by oral infection. The regression equation of virulence was y = 1.067 + 0.809x, and the lethal concentration was LC16 = 1.164 × 10.8cfu mL. In order to explore the mechanism of pathogenic effect of HR_3 on locusts, the histopathology of locust-infected HR_3 was studied. The results showed that the epithelial cells of locust were damaged in the early stage of infection, followed by local degeneration and necrosis. After 48 h of infection, most of the digestive cell layer was filled with vacuoles.