华北棉区各代棉铃虫生命表及南北棉铃虫发生特征研究

通过对以河北饶阳为代表的华北棉区棉铃虫动态的研究，建立了各代棉铃虫自然种群生命表．结果表明，华北棉区第l-4代棉铃虫总死亡率分别为98．3％、98．34％；98.69%和9.13%,各代棉铃虫种群的趋势指数I值分别为3.97、1.50、1.41和1.09.与以江苏南通为代表的南方棉区生命表参数相比较发现，无论是在南方还是在北方，棉铃虫的存活率曲线都属于A型曲线，即卵至2龄期死亡率较大，3龄以后死亡率较小的凹型曲线。南方棉区棉铃虫消亡的关键因子是风雨冲刷作用，而北方则是天敌的捕食作用；南北棉区的棉铃虫孵化期为1龄期，易受不良环境的影响，死亡率较大，为关键虫期；北方棉区主要危害世代是2、3代棉铃虫，南方棉区为3、4代棉铃虫，由此讨论了南北棉区各世代棉铃虫的发生危害特点。

Life-table of Helicoverpa armigera in Northern China and characters of population development in Southern and Northern China

The population dynamics of Helicoverpa armigera in Raoyang County, Hebei Province as an example in Northern China was researched, and its natural life table was established.The results showed that total mortality of first to fourth generations of cotton bollworm in Northern China were 98.3%, 98.34%, 98.69% and 99.13 %, and the population tendency index (I) were 3.97, 1.50, 1.41 and 1.09, respectively.A comparative analysis of the natural life table of cotton bollworm in Southern China and in Northern China showed that the survival curves were concave curves in the two cotton zones. The curve showed that the mortality of cotton bollworm was higher in its egg stage to the second instar, and lower after the third instar. The key death factor of cotton bollworm was the scouring effect of rain and wind in Southern China, and the predation of its natural enemies in Northern China. The hatch period to the first instar was the key stage in Northern China and Southern China, and in this time, its larva instar was slim, fragile and sensitive to bad circumstances, so its mortality was higher. The second and third generations were the key damage generations in Northern China, while the third and fourth generations were the key damage generations in Southern China. The development and damage characters of each generation in Northern China and in Southern China were discussed.