光对棉铃虫和烟青虫杂交的影响

The extent of hybridization between Helicoverpa armigera(Hübner) and H. assulta(Guenée) and a molecular method for identifying these species and their hybrids

【目的】力求建立一种准确鉴定室内棉铃虫Helicoverpa armigera(Hübner)、烟青虫H.assulta(Guenée)及其杂交种的分子技术,探讨棉铃虫和烟青虫杂交的可能。【方法】室内暗期设置0.5 lx黑光灯和白炽灯,测定不同配对模式下3日龄处女棉铃虫和烟青虫的杂交率;筛选可区分室内建立的棉铃虫、烟青虫及杂交种家族的微卫星位点;于架设有黑光灯的温室内释放棉铃虫和烟青虫混合种群,利用微卫星分子标记技术检测子代微卫星位点大小。【结果】两种蛾类在任何一种配对模式下均可杂交,混合种群处理杂交率为2.92%,且均为烟青虫雌蛾与棉铃虫雄蛾配对交配;黑光灯、白炽灯和黑暗条件下杂交率无显著性差异;筛选出的Har SSR1、Har SSR9和Har SSR10在两种蛾类上的等位基因片段大小不一样;两年温室实验共鉴定360头子代,混合种群中未检测到杂交后代。【结论】交配笼中棉铃虫和烟青虫能进行种间杂交,弱光不能提高二者杂交率;混合种群处理只发现一种杂交配对模式,说明了棉铃虫雄蛾的交配竞争能力更强;成功利用微卫星分子标记技术鉴定室内建立的棉铃虫、烟青虫及杂种家族,提供了一种简单准确的分子鉴定手段;两年温室实验未检测到杂交种,说明2种蛾类之间存在着交配前生殖隔离机制。

[Objectives] To establish a molecular technique that can reliably distinguish the cotton bollworm, the tobacco budworm, and hybrids between these species, to determine the effect of different kinds of light on hybridization, and the extent of hybridization in a mixed population under greenhouse conditions. [Methods] Hybridization rates under all potential kinds of pairings between 3 day-old virgin cotton bollworm and tobacco budworm adults were recorded under a 0.5 lx black lamp, an incandescent lamp, and complete darkness（control）. Microsatellite loci that could reliably distinguish cotton bollworms, tobacco budworms, and their hybrids, were identified and used to identify the resultant progeny. A mixed population of cotton bollworm and tobacco budworm adults were released in a greenhouse and their offspring screened using the previously identified microsatellite markers. [Results] Hybridization could result from all kinds of forced pairings. However, in mixed populations, the proportion of hybrids was just 2.92%, and only one kind of pairing（male cotton bollworm × female tobacco budworm） was observed. There was no significant difference in hybridization rates between the black lamp, incandescent lamp, and dark, treatments. The sizes of the microsatellite loci Har SSR1、Har SSR9, and Har SSR10, differ between the two species. No hybrids were identified among 360 offspring screened during two years research on a mixed, greenhouse population. [Conclusion] Hybridization between the cotton bollworm and tobacco budworm can occur when individuals are not free to choose mates but low intensity light does not promote hybridization. Only one kind of pairing was observed in mixed populations, suggesting that male cotton bollworms are competitively superior to male tobacco budworms in competition for mates. The cotton bollworm, tobacco budworm, and hybrids between these species, could be reliably distinguished with microsatellite markers, which provide a simple and accurate molecular identification method. Hybrids were not identified during two years study of a mixed, greenhouse population, indicating that there is premating reproductive isolation between the two species.