カメノコテントウの生態学的研究 : I.カメノコテントウとその餌種クルミハムシの野外個体群の相互関係

抄録

The response of predator population to the density and the spatial distribution of prey population (numerical response) in their natural habitat was studied by using a predatory coccinellid, Aiolocaria hexaspilota HOPE and its prey, the walnut leaf beetle, Gastrolina depressa BALY. Analyses of life tables and spatial distributions of both A. hexaspilota and G. depressa indicated the existence of a tight interaction between the two species. Namely, the main mortality factor in all the stages except adult of G. depressa was the predation by larvae and adults of A. hexaspilota, and that of A. hexaspilota larvae was dispersal and/or cannibalism caused by shortage of prey. Although the absolute amount of prey in the whole research area was sufficient to support the existing larval population of A. hexaspilota, there actually were a number of trees on which A. hexaspilota larvae became extinct due to food shortage. As the reason for this it was suggested that A. hexaspllota adults laid eggs in some trees excessively, and the larvae could not move among trees efficiently enough to compensate for such an inadequate response by the adults to the prey distribution.