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

对棉铃虫蛹的滞育进行了研究。主要研究结果如下：1.在18℃低温条件下，研究了蛹滞育的光周期反应。在短日照条件下，棉铃虫滞育发生率较高，且雄虫滞育发生率较高。2.比较了棉铃虫和烟青虫在自然条件下的滞育诱导。在棉铃虫中，部分个体能以滞育蛹的形式越冬，但随着秋季的提前，许多个体在化蛹前死亡。而烟青虫在夏季高温条件下也能诱导蛹滞育。这些结果表明，棉铃虫对温带气候的适应性不足。3.滞育倾向没有明显的地理梯度，推测蛹滞育是在亚热带秋季较低温度下长时间暴露引起的。5.在冬季平均气温高于0℃的地区，只有滞育蛹才能越冬。海藻糖可能是影响滞育率的主要因素。6.多位点间的非加性互作对滞育率有影响。此外，还发现幼虫期与滞育之间存在遗传相关性，由此推断，随着全球气候变暖的加剧，棉铃虫在日本的分布范围扩大、数量增加是完全可能的。

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.