家蚕的一种微孢子虫对小菜蛾的致病力测定

The pathogenicity of microsporidian Vairimorpha sp. isolated from silkworm to diamondback moth PluteUa xylostella (Linnaeus) (Lepidoptera: Plutellidae)

测定了从家蚕体内分离的一种微孢子虫Vairimorpha sp.对小菜蛾的致病力.室内试验结果表明,当起始侵染期为小菜蛾2龄幼虫,浓度为1×106孢子/ml时对当代小菜蛾的致病力最高,幼虫的死亡率可达80.00%～82.67%,蛹死亡率可达50.00%～52.94%,而小菜蛾雌成虫的产卵量由对照的249.64～278.38粒/雌下降到120.56～126.72粒/雌,产卵量下降50%左右;当起始侵染期为3龄幼虫,浓度为1×106孢子/ml时,当代幼虫的死亡率只有40.00%～61.33%,与起始侵染期为2龄时相差很大,蛹死亡率和成虫每雌产卵量下降率与起始侵染期为2龄时差异不大.另外,家蚕微孢子虫还可通过垂直传染方式影响下代小菜蛾幼虫的死亡率.

In this paper, the pathogenicity of Vairimorpha sp. ,a microsporidian isolated from silkworm Bombyx mori Linnaeus, to diamondback moth Plutella xylostella (Linnaeus) was tested in laboratory. The results showed that: as the initial infection stage was 2nd instar larva, the highest pathogenicities (mortalities) to larva and pupa got from 1×106 spores/ml concentration treatment ranged from 80.00% - 82.67% and 50.00% - 52.94% respectively, and the egg numbers laid by treated female ranged from 120.56 - 126.72/female, ca. 50% lower than those of control, 249.64 - 278.38/female. As the initial infection stage was 3rd instar larva, the pathogenicities (mortalities) of the same concentration treatment as that mentioned above to larva only ranged from 40.00% - 61.33% , significantly lower than those treated in 2nd instar larva, while the differences of pupal mortalities and egg numbers/female between the two treatments in 2nd and 3rd instar larva were negligible. Furthermore, the microsporidian can also affect the mortality of the host insect in next generation by vertical transmission.