Oviposition behavior of Callosobruchus chinensis (Coleoptera: Bruchidae) and weevil population growth: effects of larval parasitism and competition
1993
Ryoo, M.I. | Chun, Y.S.
The effects of oviposition behavior of Callosobruchus chinensis (L.) on life table statistics of progeny and on attack by the larval ectoparasitoid Anisopteromalus calandrae (Howard) were studied. As the number of eggs per seed increased, larval development time and survival rate decreased. Differences in mortality between treatments was caused largely by competition in the late instars. Life table statistics showed an inverse linear relationship to the number of eggs per seed. Depositing one egg per seed increased progeny production by approximately 56% compared with six eggs per seed. The functional response of A. calandrae showed a linear relationship with host density in the range of 1-64 per 100 seeds. The parasitoid searched for its hosts more efficiently when the number of eggs per seed increased from one to four; search rate of the parasitoid based on random search increased from 0.045 +/- 0.013 (mean +/- SEM) to 0.154 +/- 0.025. The results indicate that ovipositing fewer eggs per seed is also a good defense tactic for the weevil against the parasitoids. Whether parasitoids or larval competition selected the oviposition behavior is not yet clear. However, the influence of natural enemies should be studied further to understand the evolutionary process of the weevil's oviposition behavior more precisely.
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