水稻二化螟耐寒性的研究

Studies on the Cold-hardness of the Rice Stem Bore Chilo suppressalis (Walker)

水稻二化螟越冬幼虫在普通低温－15（30d），－20（4，6，8，10d），－23（4d），－25℃（4d）下的死亡率分别为3．33％，6．67％，13．33％，23．33％，26．67％，30％，56．67％；田间越冬初期、中期、后期由低温引起的死亡率分别为0，4．85％，9．96％。越冬幼虫能耐受一定的强低温－28（90min），－30（30min），－32℃（10min）。不同时期越冬幼虫的耐寒性有很大差异，其过冷却点在翌年3月中旬以前呈上升趋势，3月中旬以后又逐渐下降。不同地理纬度区越冬幼虫的耐寒性也有差异，表现为过冷却点随地理纬度的升高而上升。首次提出二化螟在越冬期间通过耐冻和避冻两种策略来越冬。

The percent death of over-wintering larva of the rice stem borer Chilo suppressalis (Walker) at constant low temperatures -15 ℃ (30 days), -20 ℃ (4, 6, 8, 10 days), -23 ℃ (4 days), -25 ℃ (4 days), respectively were 3.33%, 6.67%, 13.33%, 23.33%, 26.67%, 30%, 56.67%. During the over-wintering period, the percent death directly caused by natural low temperature were investigated in field at pre-winter, mid-winter and post-winter,i.e., 0, 4.85%, 9.96% respectively. The over-wintering larva could tolerate some strong lower temperatures: -28℃(90min), -30 ℃ (30min), -32 ℃ (10min). The over-wintering larva had different cold-hardness at different time.Before mid-March, the super-cooling point (SCP) showed rising trend, after mid-March it began to decrease.The over-wintering larva collected from different latitudes also showed some differences in cold-hardness. The SCP was rising with the latitudes increasing. It is concluded that the over-wintering larva were survival in cold winter by tolerating and avoiding strategy.