Interactions Between the Host-Plant and Mating upon the Reproductive Activity of Acanthoscelides Obtectus Females (Coleoptera, Bruchidae)

In the absence of beans, the virgin females of Acanthoscelides obtectus do not lay eggs, but retain 30 to 40 oocytes in their lateral oviducts. The presence of beans induces oviposition in the majority of females though the oocytes are deposited at random in the rearing-box. The host-plant stimulates oogenesis but the magnitude of this stimulating effect changes in subsequent generations. Mating also induces egg-laying but its influence changes with strains selected according to their behaviour in the presence of the host-plant. Interactions between host-plant and mating are complex and this work shows the importance of the variations of the influence of an external stimulus in laboratory experiments.