Ecogenetical Studies on geographical variation and gene expression of diapause in the cotton bollworm, Helicoverpa armigera.

对棉铃虫Helicoverpa armigera的滞育特性进行了研究。主要研究结果如下：1.在18℃的低温下，研究了幼虫滞育的光周期反应。在短日照条件下诱导滞育，以雄性较大。2.比较了棉铃虫和棉铃虫在半自然条件下的滞育诱导情况。在棉铃虫中，有些个体可以作为滞育蛹越冬，但许多个体在秋季提前化蛹死亡。另一方面，即使在夏季高温条件下，烟夜蛾仍能诱导出蛹的滞育。这些结果表明棉铃虫对温带气候的适应能力不强。3.滞育趋势没有明显的地理分布规律，推测在亚热带地区秋季，幼虫长期暴露在较低的低温环境下才能诱导滞育。4.估计幼虫滞育对日长的敏感期为5号。5.只有滞育的幼虫才在冬季平均气温高于0℃的地区越冬。海藻糖似乎与耐冷性有关。6.表明多基因座之间的非加性互作对滞育率有影响。此外，还发现幼虫期和滞育期之间存在遗传相关，由此得出结论，随着全球变暖的进展，棉铃虫在日本完全有可能扩大其分布和增加其丰度。

The pupal diapause of the cotton bollworm, Helicoverpa armigera, was investigated. The results obtained are summarized as follows.1.Photoperiodic response of pupal diapause was investigated at lower temperature of 18℃. The diapause was induced under short day length conditions and its tendency was greater in males.2.The diapause induction under seminatural conditions was compared between H.armigera and H.Assulta. In H.armigera, some individuals could overwinter as diapausing pupae, although many individuals died before pupation with advance in the fall season. On the other hand, in H.assulta, pupal diapause was induced even at high temperatures in summer season. These results indicated that the adaptation to temperate climate is inadequate in H.armigera.3.No clear geographical cline in diapause tendency was detected It was supposed that pupal diapause is induced when larvae were exposed to lower temperatureds for a long time in fall season of subtropical region.4.It was estimated that the sensitive stage to day-length in pupal diapause is the 5th instar.5.Only the diapausing pupae are supposed to overwinter in the region where average winter temperatures are higher than 0℃. The trehalose was seemed to be responsible for the cold hardiness.6.It was indicated that nonadditive interactions among multiple loci are influential on the diapause rate. Moreover, it was found that there is a genetic correlation between larval period and diapause.From these results, it was concluded that H.armigera is fully possible to spread its distribution and increase its abundance in Japan with progress in the global warming.