一株草地贪夜蛾囊泡病毒对甜菜夜蛾幼虫的感染特性及对其生长发育的影响

Infection Characterization by Spodoptera frugiper ascovirus Isolate 84-36 and Growing Development of Infected Spodoptera exigua Larvae

囊泡病毒是一类具有生防潜力的双链DNA病毒,本文以含草地贪夜蛾囊泡病毒84-36浓度为9.77×1012病毒基因拷贝/m L的血淋巴,分别通过口服（1~2龄：1.09×1010病毒基因拷贝/虫;3~5龄：9.77×109病毒基因拷贝/虫）与针刺（1.56×109病毒基因拷贝/虫）2种方式接种感染甜菜夜蛾Spodoptera exigua（Hübner）幼虫,观察其死亡和生长发育情况。结果表明,口服感染时,1、2、3、4和5龄幼虫的校正死亡率分别为18.89%±1.11%、4.44%±1.11%、2.22%±1.11%、0与0,1龄幼虫较2、3龄显著易被病毒感染;针刺接种感染时,3、4和5龄幼虫校正死亡率分别为100.00%、100.00%和80%,所有被病毒感染的幼虫发育历期明显延长,3、4龄幼虫感染病毒后的第2 d即表现出日取食量显著降低、第3 d开始体重基本维持不变。由此可见,草地贪夜蛾囊泡病毒84-36毒株在生物防治上具有潜在优势。

Ascoviruses are double-strand DNA viruses with potential biocontrol for the insect pests. In this study, Spodoptera frugiperda ascovirus isolate 84-36 was used to inoculate the first to the fifth instar of Spodoptera exigua（Hübner） larvae by both per os（1.09×1010 copies per larva for the first to second instar larvae; 9.77×109 copies per larva for the third to fifth instar larvae） and intrahaemocoelic injection（1.56×109 copies per larva） with the titer of 9.77×1012 genomecopies/m L hemolymph. Mortality, growth and development of the inoculated larvae were observed and recorded. While the corrected mortalities of the first to the third instars inoculated per os were 18.9%±1.11%, 4.4%±1.11%, 2.2%±1.11%, respectively, the treatment showed no effects on the fourth and fifth instars. The first instars were significantly easier to be infected by the virus than the second and the third instars. Corrected mortalities of the larvae inoculated by injection in both the third and fourth instars were 100.00%, and that in the fifth instars was 80.00%±0.00%. The survival time of the diseased larvae was apparently extended. Meanwhile, food intake of the larvae inoculated in the third and the fourth instars was reduced remarkably at day 2, and the body weight remained fairly constant from day 3-postinoculation. These results reveal that the Spodoptera frugiperda ascovirus isolate 84-36 has the potential for biological control.