Factors affecting female fecundity in the cowpea seed beetle, Callosobruchus maculatus (Coleoptera: Bruchidae)

Abstract Factors affecting female fecundity were studied in strains of C. maculatus originating from Brazil, Nigeria, and the Yemen. There was very little variation in the number of ovarioles within or between strains. The number of oocytes in the ovarioles was maximal one day after emergence of the females from the seeds in which they had developed, and then declined steadily. Most eggs were also laid during the first day after emergence. The Brazilian strain laid more eggs in the first 6 hr after mating when offered only 2 seeds rather than 40. However, the Brazilian and Yemen strains both laid fewer eggs in total on 2 seeds rather than 40, although there was no reduction in the rate of egg production until the sixth day of adult life. The eggs accumulated in the reproductive system if not laid. The loss of weight with each egg laid was greater in the Yemen strain than in the other two strains, but this could have been a consequence of a differing metabolic rate rather than the weights of the eggs themselves. Females prevented from mating for 6 days after emergence but then allowed access to seeds laid fewer eggs than females allowed to mate and oviposit immediately. Even fewer eggs were laid by females mated at emergence but then prevented from laying for 6 days. Although most females readily remated 3 days after their emergence and initial mating, remating had no significant effect on the numbers of eggs laid or the percentage hatching. Similarly, enclosing individual females with different numbers of males did not markedly affect the number of eggs. There were, however, limited changes in the percentage of eggs which hatched and the distribution of eggs on the available hosts.