光周期和温度对草地螟滞育诱导的影响

Effects of photoperiod and temperature on diapause induction in the beet webworm Loxostege sticticalis Linnaeus (Lepidoptera:Pyralidae)

草地螟Loxostege sticticalis以老熟幼虫滞育越冬。在室内通过人工诱导的方法对其滞育的光周期和温度诱导条件进行了研究。结果表明:草地螟是一种典型的长日照发育型种类。光周期、温度及其交互作用均对草地螟滞育诱导具有重要影响,其中光周期起主导作用,温度伴随着光周期起作用。对幼虫滞育诱导最有效的光周期是L12∶D12;随着温度的升高,临界光周期呈缩短趋势(18℃除外)。18,22,26和30℃条件下幼虫滞育的临界日长依次为13.97,14.48,13.92和12.88h。光敏感实验揭示:21℃时草地螟对光照反应最敏感时期为幼虫孵化后的11～17d(约5龄幼虫),但孵化后7～11d(约4龄幼虫)的短光照积累对提高滞育率也有重要作用,可以将滞育率从40.0%提高到90.0%。

To study the effects of photoperiod and temperature on the diapause induction in the beet webworm Loxostege sticticalis, the interactive effects of temperature （18, 22, 26 and 30℃ ） and photoperiod （L8： D16, L10： D14, L12： D12, L14：D10 and L16： D8） on diapause induction in this moth were investigated by artificial induction method in the laboratory. The photoperiod played the key role in diapause induction in mature larvae, followed by temperature and their interaction. Photoperiod response in L. sticticalis showed that it is a typical long-day species with a critical day length of 13.97, 14.48, 13.92 and 12.88 h at 18, 22, 26 and 30℃ respectively. The day length of 12 h resulted in the highest diapause rate at all the experimental temperatures. The larvae of 11 to 17 days after hatching （about in the 5th instar） were most sensitive to the photoperiod, suggesting that the 5th instar is the most sensitive stage of diapause induction. However, the short daylight received by the 4th instar larvae was also important for the increase of their diapause rate, which can be increased from 40.0% to 90.0%.