Author ORCID Identifier
Date Available
5-12-2025
Year of Publication
2024
Degree Name
Doctor of Philosophy (PhD)
Document Type
Doctoral Dissertation
College
Agriculture, Food and Environment
Department/School/Program
Entomology
First Advisor
Dr. Nicholas Teets
Abstract
The ability to tolerate stress is key to maintaining fitness in extreme environments such as the polar regions. Subject to a myriad of extreme year-round abiotic conditions, invertebrates inhabiting the terrestrial ecosystems of Antarctica provide an excellent system to investigate adaptations to stress. Understanding the response of these species to abiotic and novel stressors is crucial in a world with rapidly occurring climate change and increasing anthropogenic activity. In this dissertation, I investigated physiological and molecular responses to naturally occurring and human-derived stresses in the midge Belgica antarctica, which is Antarctica’s only endemic insect.
In my first research chapter, I tested the hypothesis that Antarctica’s rapidly warming winters are detrimental for insects living there. Antarctic winters last at least six months, during which time constant subzero temperatures render larvae immobile beneath the snow and ice. Unable to feed, larvae rely on stored energy stores for survival, suggesting that warmer winters that elevate metabolic rates may lead to energy drain. For this study, larvae of B. antarctica were exposed to ecologically relevant overwintering simulations in the laboratory. I demonstrate that relatively small increases in overwintering temperatures negatively impact survival and cause energy deficits. Thus, winter climate change in Antarctica may have significant implications for the survival and persistence of these cold-adapted insects.
In my second research chapter, I characterised the transcriptomic responses of B. antarctica larvae exposed to distinct sublethal abiotic stressors. The stressors, namely heat, freezing, desiccation, hyper- and hypo-osmotic stress, can be experienced concurrently or in quick succession. Consequently, as these stressors elicit costly molecular responses, shared protection is inherently beneficial in maximising fitness. To determine the extent to which cross-protection may be present across these stressors, I quantified the degree of mechanistic overlap and showed that cross-protection between stressors is likely modulated by a combination of cross-talk and cross-tolerance. Furthermore, I demonstrate that distinct stressors that induce cellular dehydration produce the most similar gene expression responses. Together, this work provides a comprehensive resource for molecular responses to stress in B. antarctica.
In my third chapter, I review the prevalence of microplastics in Antarctica and the potential consequences of this anthropogenic pollutant on terrestrial invertebrate communities. I place focus on the physiological consequences of MP exposure and ingestion in related invertebrate taxa, integrated with the responses of Antarctic invertebrates to other stressors. I discuss both the potential direct and indirect consequences of microplastics on these simple ecosystems and make recommendations for future work.
In my final research chapter, I investigated physiological consequences of microplastic exposure in larvae of B. antarctica, as well as the prevalence of ingested microplastics within field-collected larvae. In this work, I demonstrate that microplastic exposure decreases lipid stores following 10 days of exposure. Within field-collected larvae, we detected a low incidence of ingested microplastics, providing evidence that microplastics have entered the food chain in terrestrial Antarctica, albeit at low levels.
Taken together, my work improves our understanding of the response of how a polyextremophile invertebrate responds to both abiotic and anthropogenic stressors.
Digital Object Identifier (DOI)
https://doi.org/10.13023/etd.2024.166
Funding Information
This work was supported by the National Science Foundation Grant (OPP-1850988) and the Antarctic Science Ltd Bursary (1000404642).
Recommended Citation
Devlin, Jack J., "Consequences of Abiotic and Anthropogenic Stressors in the Antarctic Midge, Belgica antarctica" (2024). Theses and Dissertations--Entomology. 83.
https://uknowledge.uky.edu/entomology_etds/83
