A window into fly sex: mating increases female but reduces male longevity in black soldier flies

Abstract

Sexual reproduction increases genetic diversity but it is also associated with costs such as exposure to parasites or reduced life span. Black soldier flies, Hermetia illucens, are a suitable model to investigate the trade-offs between reproduction and longevity as they largely rely on their larval resources and do not have to feed as adults. Here, we investigated the influence of mating status on adult longevity. We found that females had shorter longevity than males, but the intersexual difference in life span was reduced through mating which increased female but decreased male longevity. This suggests a cost of mating for males, while female longevity increased, likely via nutrients transferred by males during copulation (sensu nuptial gifts). We also investigated the transparent abdominal ‘window’ of adult black soldier flies, the fullness of which may be a proxy for both age and mating status. Window fullness decreased with age in unmated males whereas unmated females maintained high fullness until they were older. Additionally, mated females mostly had full windows while those of mated males were mostly empty. Our findings have not only expanded our understanding of resource allocation in this species, but they also harbour great potential for applicability in the industrial sector given the extensive use of black soldier flies in organic waste management.

Topics & Concepts