一株蝗虫病原菌的鉴定及其毒力和病理研究

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（Serratia marcescens）。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=1.067+0.809x，致死中浓度LC50=1.164×108cfu/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48h后，消化细胞层大部分区域被空泡状物充盈。

Identification of a pathogenic strain of locusts and its toxicity and pathology

A pathogen was isolated from naturally dead grasshoppers. Its pathogenicity was testified by law of KOCH. It was identified as Serratia marcescens by physiological, biochemical test and molecular systematic analysis. Toxicity of HR-3 to grasshoppers was assayed by means of oral infection. The results show that the linear regression relationship between the logarithm(y) of HR-3 concentration and the probability (x) of corrected grasshopper morality is y = 1.067 + 0.809x, and the median lethal concentration is LC50 = 1.164 x 10(8) cfu/mLo The infection mechanism of HR-3 to grasshoppers were also studied. The histopathological studies show that midgut epithelia are damaged at the beginning of infection, and then partial denaturalization and putrescence occurr in this area. After 48h infection, vacuoles appear in most regions of midgut epithelia.