The advantage of virginity in cold-exposed Callosobruchus maculatus

Abstract

Understanding the influence of environmental stressors on pest reproduction is critical for effective management strategies, particularly in a changing climate. This study investigates the reproductive output and biological parameters of the cold-exposed cowpea weevil, Callosobruchus maculatus, focusing on the effects of keeping insects virgin during cold exposure versus allowing copulation before exposure. Newly emerged adults were exposed to either optimal (30 °C) or cold (4 °C) temperatures for four days. Virgin insects copulated after treatment termination. By manipulating temperature treatments and mating status, we investigated how these factors affected a suite of life-history traits, including longevity, egg number, hatch percentage, adult emergence, and mating behaviors. Our findings demonstrate that virginity substantially extends longevity in both sexes under normal temperatures. We observed a trade-off between survival and reproduction in virgin cold-exposed C. maculatus. Mating status (virginity or being mated) during cold exposure did not affect males' and females' longevity; however, it influenced reproduction output. Notably, cold-exposed females that were virgin during cold exposure laid more total eggs (212.28) in their life and these eggs had a higher hatchability (91.60%) than eggs of insects that were copulated during cold exposure (112.67 eggs and 78.79% hatchability). Although cold exposure in males and females can extend the adult lifespan, it considerably reduces reproductive success. Mating trials showed that cold stress strongly reduced mating success, with cold-exposed females showing increased rejection rates and altered copulation duration. These results indicate a vital role for mating status in determining reproductive outcomes under environmental stress. Future research should explore the applicability of these findings to other pest species and develop adaptive pest management strategies.