Thermal impacts on insect reproduction

Cole, Benjamin John (2025) Thermal impacts on insect reproduction. Doctoral thesis, University of East Anglia.

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Abstract

Humans are driving significant changes to Earth’s climate, resulting in both an increase in the mean global temperature and a rise in the incidence of extreme heat. Heatwaves are becoming more common and intense, which is particularly concerning given that they are predicted to have a greater ecological impact than increases in mean temperature alone.

Insects are the most diverse and abundant group of animals on the planet, and underpin a host of essential ecosystem processes. Their ectothermic physiology makes them particularly susceptible to thermal stressors such as heatwaves. Throughout this thesis, Tribolium castaneum is utilised to assess the impacts of ecologically relevant heatwave exposures on survival, reproduction and gene expression. This species serves as a model to represent how insects may broadly respond to heatwaves under current and future climate change scenarios.

Throughout this thesis, it is demonstrated that Tribolium castaneum is resilient to less intense heatwaves of 42°C and 44°C. However, as temperatures increase from this point, the resilience of key focal groups (virgin males, virgin females, mated males, and mated females) fails dramatically. Widespread reductions in survival and fertility were observed in response to heatwave exposures of 46-50°C, temperatures which are projected to become commonly seen across large areas of this species’ global distribution under climate change. Most concerningly, it is demonstrated that mated females show the greatest vulnerability to such heatwave exposures. Mated females exhibited reductions in survival under less intense heatwave conditions than the other focal groups and consistently showed worse survival than all other focal groups in response to identical heatwave conditions. This vulnerability is further investigated through the examination of transcriptional responses to a 48°C, 5-hour heatwave exposure. Under these conditions, it is demonstrated that post-mating, females fail to mount a molecular heat stress response, providing a potential mechanism underlying the vulnerability of mated females to heatwaves.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	07 Sep 2026 08:25
Last Modified:	07 Sep 2026 08:25
URI:	https://ueaeprints.uea.ac.uk/id/eprint/104436
DOI:

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