家蚕病原性微孢子虫多样性调查分析

[目的]从分布、感染性和分类特征三方面调查家蚕病原性微孢子虫多样性,为蚕业生产上有效防控家蚕微粒子病提供参考依据.[方法]跟踪蚕种生产微粒子病检疫数据及抽样检验家蚕受微孢子虫感染的情况,调查家蚕病原性微孢子虫的分布;通过测定微孢子虫对家蚕的半数感染浓度(IC50)和胚种传染率及检验带毒蚕种的微粒子病胚种传染率,调查家蚕病原性微孢子虫的感染性;基于微孢子虫SSU rRNA序列构建家蚕病原性微孢子虫系统发育进化树及进行相似性和遗传距离分析,调查家蚕病原性微孢子虫的分类特征.[结果]不同时间和不同蚕区生产饲养的广西家蚕均存在一定量的微孢子虫感染,蚕种微粒子病发生率(毒率)呈波动起伏态势.GXM3、GXM4、GXM5、GXM6、GXM7、GXM8、GXM9、GXM10、GXM11、GXM12和GXM13等11株异型微孢子虫对家蚕均具有较强食下传染力,大部分异型微孢子虫对家蚕的IC50与N.b同一级别;各种微孢子虫对家蚕的胚种传染力存在明显差异,N.b的胚种传染率达51.67%,其他异型微孢子虫均比N.b低,部分异型微孢子虫(GXM6和GXM13)对家蚕无胚种传染力.GXM3、GXM4、GXM5、GXM6、GXM7、GXM8、GXM9和GXM11等8株异型微孢子虫均位于Nosema属的类群分支上,除GXM7与GXM9、GXM3与GXM5间存在较低分化度和较高相似度外,其他微孢子虫间的分化度和相似度均存在明显差异.[结论]广西蚕区家蚕病原性微孢子虫分布广泛,种类繁多,且各种微孢子虫的感染力存在明显差异,即广西家蚕病原性微孢子虫存在丰富的种类多样性.

Diversity of pathogenic microsporidan of Bombyx mori

[Objective]The present experiment was conducted to survey the diversity of pathogenic microsporidan of Bombyx mori from the perspectives of their distribution,infectivity and taxonomic character to provide reference for effec-tive prevention of bombyx m. pebrine in sericulture.[Method]The pebrine inspection data of B. mori eggs was analyzed and the sampling inspection of B. mori was carried out to find out the distribution of pathogenic microsporidan. The infec-tivity of pathogenic microsporidan was researched according to test the semi-infection concentration(IC50),germinative infection rate and germinative infection rate of susceptible B. mori eggs. Phylogenetic tree of microsporidan was construc-ted based on SSU rRNA sequences,analysis on similarity and genetic distance was also carried out to investigate the classi-fication characters of pathogenic microsporidan.[Result]There were some diseased B. mori being infected by microspori-dan in different times and different regions,the pebrine contamination rate(poison rate)of B. mori eggs had obvious fluc-tuation. The pathogenic microsporidan all had strong ingestive infection to B. mori,such as GXM3,GXM4,GXM5, GXM6,GXM7,GXM8,GXM9,GXM10,GXM11,GXM12 and GXM13,the IC50 of most microsporidan had the same level as N.b,but there were obvious differences in the germinative infection between various pathogenic microspori-dan. The germinative infection rate of N. b was 51.67%,which was more than that of other pathogenic microsporidan. Some microsporidan had no germinative infection to B. mori,such as GXM6 and GXM13. There were eight pathogenic microsporidan that were all located in the Nosema family in phylogenetic tree,which were GXM3,GXM4,GXM5, GXM6,GXM7,GXM8,GXM9 and GXM11. They showed obvious differences in divergence and percent identity with other pathogenic microsporidan,expect that there were low divergence and high level of identity between GXM7 and GXM9,GXM3 and GXM5.[Conclusion]There is wide distribution and variety for the pathogenic microsporidan of B. mori in Guangxi sericulture,and their infection had obvious differences,which means the pathogenic microsporidan of B. mori in Guangxi sericulture have rich diversity.