马尾松毛虫种群消长与寄主受害程度的关系

研究不同受害程度松林与马尾松毛虫Dedrolimuspunctatus(Walker)种群发育阶段的关系。结果表明,松毛虫大面积发生时松林的受害程度可以很好地标示着松毛虫种群的发生阶段。松林点片受害显示松毛虫种群进入上升开始阶段;松林受害程度中等时,松毛虫仍处于上升种群阶段;当松林的针叶被吃光,表明松毛虫已处暴发阶段。松毛虫暴发种群在自然情况下,将出现典型的蛹期和下一代卵期的寄生率大幅度升高、雌性比、蛹重和产卵量等种群参数大幅度下降等特征;其后代会自然转入下降种群或进入低虫口期。但这些暴发种群的卵转入在保证充足饲料的可控条件下饲养时,其后代的生长发育、存活率、性比、蛹重等主要种群参数没有明显差异。即没显示出上升种群和暴发种群的特征差异,说明暴发种群的终止主要是受外界环境的限制而不是松毛虫本身的内因所致。

Relationships between different damaged degrees of pine forest and population fluctuation of masson pine caterpillars, Dendrolimus punctatus

The relationship between different damaged degrees of pine forest and population dynamics of masson pine caterpillars, Dendrolimus punctatus were examined. Three occurrence stages, i.e. ascendance, outbreak and decrease of pine caterpillars' population during their occurrence period can be best described by using the damaged degree of pine forest in large areas. It is expressed that pine caterpillars' population enter ascending stage when the pine forest was damaged fragmentary by caterpillars and became ascending stage after the pine forest was suffered medium damage. If almost all of the pine needle were eaten up it is showed that population enter the outbreak stage. At this stage, the parasitical rate of nature enemies during pupal stage or next generation of pine caterpillars increased and the population parameter such as female ration and eggs amount of pine caterpillars decreased. However, no significant difference of parameter population were observed in pine caterpillars when the eggs of pine caterpillars from outbreak population were reared in laboratory, suggesting that the termination of population outbreak during their occurrence period is determined by environmental but not by pine caterpillars themselves.