温州市第三代二化螟大发生原因分析

第 3代二化螟大发生是由防治第 2代时失去最佳防治适期 ,而使其绝大部分幼虫存活下来 ,成为第 3代有效虫源所致 ;二是发生时间早 ;三是早稻收割期天气差 ,使 2代向 3代的转化率提高。1998温州市第 3代二化螟大发生正是由于上述 3个原因综合的结果 ,发生面积达 13.5万公顷 ,占当年晚稻面积的 95%以上 ,防治面积达 18万公顷 ,为该市近 10年来所少见。

Outbreak of the third generation of Chilo supperssalis in Wenzhou

The reasons of the outbreak of the third generation of Chilo supperssalis in Wenzhou in 1998 are analysed. The first was failing to control its second generation in a proper period and most of the individuals survived to become the effective source of the third generation.Second, the early occurrence of the third generation. The last, cloudy and rainy weather in harvesting period of early rice led to a high transforming rate of the second generation to third generation.The outbreak affected a wide area of 135000hm 2,95 percent of late rice area, and the control area reached 180000hm 2.This kind outbreak was rare in last ten years in Wenzhou.