Callosobruchus larval competition and its consequences for male and female adults

Abstract

AbstractThe struggle for life is generally the most intense among individuals of the same species because they compete to access the same food, territory, and mates. In the current study, we used Callosobruchus maculatus to investigate how males and females respond to a competitor's presence inside a bean. We monitored males' and females' from egg to adult developmental time, adult emergence, copulation success, copulatory behaviors, fecundity, egg hatching percentage, and adult longevity. Our findings revealed that a competitor's presence during immature life did not influence developmental time and adult longevity in females and males. Also, the environmental condition of living with a potential competitor in the immature stages could not significantly affect adult beetle mating behaviors compared to beetles reared alone. However, female larvae were more likely to interfere with competitors than males. Females' neighbors died sooner (mainly in the larval stage) than males (primarily as pupae). Also, when we paired males and females whose competitors died in the larval stage, female adult longevity decreased compared to without competitor control pairs. However, male adult longevity in all examined pairs was similar and was not affected by their mate's conditions. A competitor's presence during larval development decreased the insect fecundity and, at the same time, increased egg hatching percentage in all treatments regardless of the competitor's sex, or if the competitor died, compared to the control (reared alone individuals). In all, females show more interference than males toward a potential competitor.