著者

中村 浩二

出版者

日本生態学会

雑誌

日本生態学会誌 (ISSN:00215007)

巻号頁・発行日

vol.26, no.3, pp.125-134, 1976-09-30

被引用文献数

1

---

The author carried out three experiments under field and laboratory conditions to evaluate the role of intraspecific regulatory machanisms in the population dynamics of the 28-spotted lady beetle. Experiments were started by introducing the adults at different densitiesinto the field cages. With increasing parental density, the number of eggs laid per female decreased and the percentage of eggs eaten by adult beetles (egg cannibalism) increased, and in consequence of these processes, egg mortality became higher. During the larval stage the mortality was mainly due to food shortage. The number of progeny produced per female was decreased in a density dependent manner. A graphical key factor analysis proposed by VARLEY and GRADWELL revealed that the density dependent regulation mechanisms scting in the adult stage, viz, the reduction in fecundity and egg cannibalism, were the key factors govering the variation in total survival in these experiments.