Sex differential effects of developmental heat stress on life-history and reproductive traits

Tuba Rizvi , Deep Sehgal, Klaus Reinhold

Global warming has led to increased mean global temperatures with projections suggesting continued warming throughout this century, posing an escalating threat to biological systems worldwide. Ectotherms are most vulnerable to this change as heat stress conditions can have severe implications on their development, mating interactions, and fitness. However, the sex-specific effects of developmental temperature on these factors remain poorly understood. Here, we conducted an experiment using the decorated cricket, Gryllodes sigillatus, to disentangle sex-specific effects of developmental temperature on life-history, pre- and post-copulatory and fitness-related traits. Crickets were reared at two temperatures: a control temperature (27 °C) and a heat-stress temperature (36 °C) and their development was monitored. Post sexual maturation, mating assays were conducted in a full-factorial mating design, and after successful fertilization, reproductive output was quantified. We found that heat stress accelerated development to adulthood differentially in both sexes. Furthermore, we found that female developmental temperature affected mating latency, with heat-stressed females exhibiting longer latencies, suggesting that females exert control over this trait. Conversely, male developmental temperature affected courtship and copulation success. Heat-stressed males were less willing to initiate courtship and largely unsuccessful at transferring the spermatophore during mating. Post-copulation, heat stressed females took longer to feed on the nuptial gift. Moreover, the feeding time was also significantly predicted by the wet mass of both males and females, suggesting that gift consumption is driven by a combination of male-provided quality and the female’s own energetic requirements. Lastly, we found that heat-stressed females exhibited significantly reduced fecundity and fertility, highlighting downstream reproductive costs of developmental thermal stress. Thus, our study highlights how developmental temperature alters life history, fertility, and can have sex-specific impact on shared mating traits.