家蚕与野外昆虫间微孢子虫交叉传染性及其传染机制

Silkworm pebrine was the most serious epidemic disease for sericulture, the pathogen source was complex. Many studies suggested that the increased incidence of silkworm pebrine in silkworm egg production was because of microsporidia cross-infection between wild insects and silkworm, but the definite evidence was lack for that correlation. This project take heterotypic microsporidia and insect microsporidia as research objects, then research the origin of heterotypic microsporidia and the infection of insect microsporidia by the ways of relation- ships analysis with pathogenic classification and investigation on the pathogen distribution, and research for the microsporidia cross-infection between silkworm and wild insects under different environment. Therefore, the project search the epidemic species of heterotypic microsporidia in silkworm egg production, that will provide the basis for reasonable judgment of silkworm egg quarantine; and search the main species of insect microsporidia which has cross-infection to silkworm in Guangxi sericulture area, that will provide the basis for make reasonable measures to control silkworm pebrine. The project research on the mechanism of cross-infection between silkworm and wild insects, which will provide a scientific basis and theoretical reference to establishment of an effective way to control the microsporidia cross-infection between wild insects and silkworm, and provide reference to control microsporidia disease in the biological world.

家蚕微粒子病是养蚕业中最为严重的一种疫病，该病病原来源复杂，很多研究认为野外昆虫微孢子虫对家蚕的交叉传染是目前蚕种生产中微粒子病发生率上升的重要原因，但一直缺乏确切证据证实两者的相关性。本项目以感染家蚕的异型微孢子虫和野外昆虫微孢子虫为研究对象，采取病原分类分析不同微孢子虫近缘关系和生产环境分布调查相结合分别探讨广西蚕区异型微孢子虫的来源和野外昆虫微孢子虫的传染问题，并在不同环境下调查家蚕与野外昆虫间微孢子虫的交叉传染性。通过上述研究，查找在广西蚕种生产中存在流行趋势的异型微孢子虫，为蚕种微粒子病检疫合理判断提供依据；查找在广西蚕区与家蚕存在交叉传染微孢子虫的主要昆虫，为蚕业生产采取合理措施防控家蚕微粒子病提供依据；探讨家蚕与野外昆虫间微孢子虫交叉传染机制，为建立阻断野外昆虫微孢子虫对家蚕交叉传染有效途径提供科学依据和理论参考，也为生物界防控微孢子虫病发生提供借鉴。

微孢子虫（Microsporidian）寄主非常广泛，可寄生从无脊椎动物到脊椎动物，是一种人畜共患的病原，还是一种嗜昆虫的病原。家蚕是一种重要的经济昆虫，受到微粒子病危害巨大。以家蚕病原性微孢子虫和野外昆虫微孢子虫为研究对象,双向探讨家蚕与野外昆虫间微孢子虫交叉传染性，了解微孢子虫种类、传染路径和机制，为完善家蚕微粒子病有效防控措施具有重要指导意义。. 本项目检测传统蚕区蚕种生产和白裤瑶区饲养的家蚕样品，调查家蚕病原性微孢子虫的分布及来源；同时在养蚕环境收集野外昆虫调查微孢子虫的分布、种类及对家蚕的致病性。项目发现广西蚕区家蚕（包括瑶蚕）受到很多微孢子虫感染，家蚕病原性微孢子虫种类多，来源复杂，测定的微孢子虫对家蚕均具有较强食下传染力，但它们的胚种传染力较低低；测定的微孢子虫均属于Nosema属微孢子虫，与Nb同属异种，其中发现部分家蚕异型微孢子虫与野外昆虫（如甜菜夜蛾、熊蜂等）微孢子虫的亲缘关系密切。还发现广西蚕区野外昆虫微孢子虫资源分布广泛，大部分昆虫均感染有微孢子虫，其中鳞翅目昆虫感染率较高，如菜粉蝶、稻纵卷叶螟、桑尺蠖、桑螟等昆虫均有较高微孢子虫感染率，而白裤瑶区的野外昆虫也有很高的微孢子虫感染率；部分昆虫微孢子虫可食下感染家蚕，部分还具有一定的胚种传染力；测定的微孢子虫均属于Nosema属，与Nb同属异种，其中白裤瑶区昆虫微孢子虫与瑶蚕微孢子虫关系密切。项目证实家蚕受到昆虫微孢子虫交叉传染，其中鳞翅目昆虫带来的风险最大，这些昆虫通过鳞毛、粪便尸体等污染桑叶进而感染家蚕；当养蚕生产有严重的微粒子病，家蚕病原性微孢子虫会通过蚕沙污染环境进而传染野外昆虫，造成微孢子虫更大规模传播扩散。另外，人类经济活动，携带和销售带毒蚕种，也是传播微孢子虫的重要方式。. 项目成果了解家蚕和野外昆虫微孢子虫的多样性及其传染传播机制，为建立阻断微孢子虫扩散的有效方法提供科学依据，也为生物界防控微孢子虫病发生提供借鉴。