The study of effect of infected bean density in larval stage on biological parameters and mating behaviors of the cowpea weevil Callosobruchus maculatus

The cowpea weevil Callosobruchus maculatus (Fabricius, 1775) (Coleoptera: Chrysomelidae) is used as a model insect to study various aspects of biology, behavior, or intraspecific competition due to its short life cycle and ease of breeding. In this study, using beans with an egg, the effect of other larvae in adjacent beans and not in the same bean during the growth period has been investigated on the possible feeling of competition in the insect and mating behaviors in adulthood and biological parameters in the F0 and F1 generations. Developmental time, the number of eggs, hatching percentage, adult longevity, and the sex ratio of the next generation were assessed. The results showed that the larvae of the cowpea weevil were able to detect the presence of larvae in the beans that were in contact with their beans, and they changed their behavior in adulthood under its influence. In adulthood, these insects had a successful mating percentage, and a shorter copulation duration than insects raised alone in a container and did not feel the presence of any competitors. Other studied biological parameters (such as mating latency and kick duration) did not change significantly under the influence of treatments. Therefore, insect breeding conditions (the presence of only one bean with one larva inside it in a container or compaction of several beans with a single larva inside each) significantly affect insect mating behaviors in adulthood. This should be considered in the design of various experiments.