ニジュウヤホシテントウの生態学的研究 : I.野外個体群の生命表と死亡過程の分析

概要

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Life table studies were carried out on the 28-spotted lady beetle in a suburb of Kyoto city, in 1970-72. Overwintered adults oviposited their eggs mainly in potato fields and the new adults of the first generation emerged in late June-early July. Egg mortality was 27% and was mainly attributed to physiological causes and cannibalism by larvae, while food shortage was the main cause of death during larval stages. Total mortality from egg to adult emergence was 90%. After the potato was harvested, the number of adults which immigrated from potato to the egg plant and other Solanaceae crops was so large that they were subjected to severe food shortage, dispersal and reduction in fecundity in consequence of overcrowding. In the second generation, egg mortality, ranging from 40-60%, was higher than in the first generation. This was largely due to egg cannibalism by adult beetles. Total mortality was 94-99.7% and a few adults emerged in early August. It is concluded that some density dependent intraspecific mechanisms, viz, regulation of fecundity, egg cannibalism, competition for food among larvae and adult dispersal, play a significant role in the population dynamics of the 28-spotted lady beetle.
日本生態学会の論文
1976-06-30