马尾松毛虫种群动态趋势探讨——用临界分化日预测二、三代分化率

马尾松毛虫 ( Dendrolimus punctatus Walker)在我国长江沿岸各省 ,即相当 30°N地区 ,存在着二、三代分化现象。所谓二、三代分化 ,就是在同一地区 ,每年第二代松毛虫卵孵出的幼虫中 ,一部分可以生长发育至结茧、化蛹、羽化 ,即每年出现 3次成虫 ,以第三代幼虫越冬 ;而另一部分 ,幼虫生长至四、五龄后即进入冬蛰 ,就以第二代幼虫越冬。它们出现的比例 ,在同一地区 ,又随着年份和其它条件的不同而不同。至于二、三代分化对种群动态的影响 ,过去在实践中往往遇见 ,在高虫口区 ,二代虫也会突发成灾。这是由于当年三代虫的比例增加 ,二代老龄…

Trend of Pine Caterpillar (Dendrolimus punctatus) Population Dynamics--Forecasting the Differentiation Rates of the Second and Third Generation by Means of Critical Date of Differentiation

Based on the mechanism of differentiation of Dendrolimus punctatus in the area with the latitude of 30° N,the differentiation rates of the second and third generation can be determined by evaluating the hatching rate of the second generation larvae,so as to forecast the dynamics trend of local populations. The practical forecast and verification conducted in Gaoan,Wannian,Yujiang and Linchuan counties of Jiangxi Province in 1993 proved that it is feasible to forecast the differentiatin of the second and third generation by critical differentiation date.