二化螟水稻类群和茭白类群成虫产卵与幼虫寄主选择行为的比较研究

实验室木箱条件下进行的二化螟水稻类群与茭白类群成虫产卵选择性试验结果表明，两类群在水稻与茭白上所产的卵块和卵粒的分布及孵化率无显著差异；但均有将不能孵化卵产在非本寄主上的倾向．通过Y形嗅觉仪进行的幼虫寄主选择行为的试验结果显示，除茭白类群1龄幼虫对水稻与茭白的趋性分别为30．00％与66．67％，有显著差异(P≤0．05)外，1龄幼虫对两寄主组织的趋性无显著差异；对水稻与茭白叶片、叶鞘的趋性反应中，水稻类群4龄、6龄幼虫对叶片，2龄、4龄幼虫对叶鞘差异显著，而茭白类群2—6龄幼虫均差异显著(P≤0．05)．研究结果表明，两类群已开始种下分化，其中茭白类群对本寄主的专化程度大于水稻类群。

Comparing study on oviposition preference and host-selecting behavior of larvae of rice and water-oat population of rice stem borer,Chilo suppressulis

The oviposition preference of female of rice and water-oat population of rice stem borer was studied in the oviposition cage (1 m x 1 m x 0.8 m) in laboratory. The results showed that there was no significant difference between the numbers and distributions of eggs laid by the two populations, but each population preferred to lay its non-hatching ovum on the non-host plant. The host-selection behavior of larvae of two host populations was also investigated by Y-tube olfactory. When the leaf or leaf shell of rice and water-oat was provided to larvae of rice population in choice test, 4th and 6th instar larvae of rice population preferred rice leaf to water-oat leaf and 2nd and 4th instar larvae preferred leaf shell of rice to leaf shell of water-oat. When leaves of rice and water-oat were provided to larvae of water-oat population in choice test, except for 1st instar, each stadium of larvae preferred water-oat leaf to rice leaf, and when leaf shells of rice and water-oat were provided, all stadiums of larvae preferred leaf shell of water-oat to leaf shell of rice. These results demonstrated that intraspecies differentiation between the two populations, and the specialization of water-oat population of rice stem borer to host was higher than that of rice population.