昆虫微孢子虫对家蚕的感染力及其增殖情况研究

【目的】了解广西野外昆虫微孢子虫对家蚕交叉感染及增殖情况,为有效防治家蚕微粒子病提供科学依据。【方法】从野外昆虫菜粉蝶、桑尺蠖、斜纹夜蛾的体内收集到5种不同来源的微孢子虫,以家蚕微孢子虫（Nosema bombycis,N.b）为对照,检测不同来源昆虫微孢子虫对家蚕的感染力,并通过镜检和染色观察各种昆虫微孢子虫在蚕体内繁殖情况。【结果】从菜粉蝶分离获得的微孢子虫（PrLM）、从不同来源桑尺蠖分离获得的2种微孢子虫（PaBMI和PaBMII）、从不同来源斜纹夜蛾分离获得的2种微孢子虫（SlMI和SlMII）及家蚕微孢子虫（N.b）对家蚕的半数感染浓度（IC50）分别为4.67×10^4、8.12×10^5、1.13×10^7、8.14×10^7、3.51×10^7和1.16×10^4个/mL;各种昆虫微孢子虫在蚕体内孢子增殖力均很低,镜检发现,PrLM和PaBMI每个视野下见到1-10个孢子,而PaBMII、SlMI和SlMII需要几个视野才见到1个孢子;染色观察发现,PrLM和PaBMI感染后可以形成大量裂殖体,但很难形成成熟孢子。【结论】广西野外昆虫微孢子虫对家蚕具有较强的交叉感染危害,尤其是对蚕种生产危害很大,但在蚕体内增殖能力较低。

Infectiousness of insect microsporidia to Bombyx mori and its propagation

Objective]The present study was conducted to investigate the infectiousness of insect microsporidia to silkworm and its propagation in silkworm in order to study the control of silkworm pebrine. Method]Five kinds of microsporidia were collected from field insect species, viz., Pieris rapae, Hemerophila atrilineata and Podenia litura from sericultural areas of Guangxi. By using microsporidia of Bombyx mori Nosema bombycis （N.b） as the control, the infectivity of different microsporidia to B.mori and their propagation in silkworm body were investigated. Result]The IC50 （50% infectious concentration） of the microsporidia isolated from P. rapae （PrL M）, H.atrilineata （PaB M I）, H.atrilineata （PaB MⅡ）,Slitura （SI M I）, Slitura （SI MⅡ）, and N.b were 4.67×10^4, 8.12×10^5, 1.13×10^7, 8.14×10^7, 3.51×10^7 and 1.16×10^4 individual/mL, respectively. The reproductive capacity of 5 kinds of insect microsporidia was low, and there were only 1-10 spores in each field of microscope for PrL M and PaB MI, and only 1 spore in several fields of microscope for PaB MⅡ, Sl MⅠand Sl MⅡ. There were more schizonts in silkworm intestinal wall after infected with PrL M and PaB MⅠ, but they hardly grew into mature spores. Conclusion]Insect microsporidia in field had stronger cross-infection damage on Bombyx mori, especially on production of silkworm eggs, but they had low reproductive capacity in silkworm body.