兴安落叶松鞘蛾种群密度的自然调节及意义

鞘蛾种群数量不可能无限制增长,其原因是多方面因素综合作用的结果。风、食物、天敌及鞘蛾的自身密度等对鞘蛾的数量增长都有明显的抑制作用。春风能使树冠上27％左右的鞘蛾幼虫落地;早霜、晚霜、松毛虫、叶蜂及落叶松早期落叶病等都能直接影响鞘蛾食物的质量和数量,进而间接地使鞘蛾种群密度降低。捕食鞘蛾的天敌主要有鸟类、蚂蚁和蜘蛛;寄生性天敌多属于金小蜂科(Pteromalidae)、姬小蜂科(Eulophidae)、姬蜂科(Ichneumonidae)及茧蜂科(Braconidae)等。由鞘蛾自身密度所引起的自我调节是促使种群进化发展的重要因素之一,但是,这种因素的作用只有在密度大的时候方能显现出来。

NATURAL ADJUSTMENT AND SIGNIFICANCE OF POPULATION DENSITY OF LARCH CASEBEARER(Coleophora dahurica Flkv.)

The increasing of the population of C. dahurica was controlled by comprehensive factors of wind, foods, predators and the density of its self. Spring wind caused 27% of larvae on crown to fall down. Early and late frost, Dedrolimus superans, sawfly and needle cast of larch could reduce the quality and quantity of foods of larch casebearer and had indirect effects on its population density. Birds, ants and spites were the main predators or C. dahurica and Ptermalidae, Eulophidae, Ichneumonidae and Braconidae etc. were parasitic predators. Self-adjustment of population caused by self-population density was an important factor to promote evolution and development of the population, but it only occurcd at high density.