Photo of Heath MacMillan

Heath MacMillan

Associate Professor

Degrees:B.Sc., Ph.D. (Western)
Office:Office: 251 Nesbitt Building
Lab: 234A Nesbitt Building
Website:Visit my Lab Website


Environmental stressors set limits to animal performance (e.g. movement, growth, and reproduction) and thereby limit fitness. These effects of stressors are all mediated through molecular biology, biochemistry, and physiology. If we want to fully understand the impacts of stressors on animal distribution and abundance, or plan for the best ways to mass rear animals, we need to understand the mechanisms of stress tolerance.

In the MacMillan Lab, we study how and why different variables in an animal’s environment, like extreme temperatures, plastic pollution, or diet, set limits to individual performance and survival, and how differences in tolerance to these stressors among individuals, populations, and species arise. To do this, we use several insects as models, like crickets, fruit flies, and mosquitos.

By integrating observations at the molecular, cellular, tissue, organ, and whole animal levels we build and test conceptual models that can explain performance. Using these models as a backbone for new questions, we study the mechanisms that allow for the wide variation in performance and fitness we observe among individuals, populations, or species in nature.

Heath welcomes inquiries from talented and motivated scientists looking to start a project on insect physiology, biochemistry, and/or molecular biology. See the lab website for details on available positions.

Selected Publications

Andersen, M.K., Robertson, R.M., MacMillan, H.A. (2022) Plasticity in Na+/K+-ATPase thermal kinetics drives variation in the critical thermal minimum of adult Drosophila melanogaster. The Journal of Experimental Biology 225: 244923.

O’Neill, E., Davis, H.E., MacMillan, H.A. (2021) A lack of repeatability creates the illusion of a trade-off between basal and plastic cold tolerance. Proceedings of the Royal Society B: Biological Sciences 288(1964): 20212121.

Fudlosid, S., Ritchie, M.W. Muzzatti, M.J., Allison, J.E., Provencher, J., and MacMillan, H.A. (2022) Ingestion of microplastic fibres, but not microplastic beads, impacts growth rates in the tropical house cricket Gryllodes sigillatus. Frontiers in Physiology 13: 1-12.

Ritchie, M.W., Dawson, J., MacMillan, H.A. (2021) A simple and dynamic thermal gradient device for measuring thermal performance in small ectotherms. Current Research in Insect Science.

Carrington, J., Andersen, M.K., Brzezinski, K., MacMillan, H.A. (2020) Hyperkalemia, not apoptosis, accurately predicts chilling injury in individual locusts. Proceedings of the Royal Society B: Biological Sciences. 287: 20201663.

MacMillan, H.A. (2019) Dissecting cause from consequence: A systematic approach to thermal limits. The Journal of Experimental Biology 222: jeb191593.

Overgaard, J.O., MacMillan H.A. (2017) The integrative physiology of insect chill toleranceAnnual Review of Physiology 79, 187-208.

MacMillan, H.A., Knee, J.M., Dennis, A.B., Udaka, H., Marshall, K.E., Merritt, T.J.S., Sinclair, B.J. (2016) Cold acclimation wholly reorganizes the Drosophila melanogaster transcriptome and metabolome. Scientific Reports. 6: 28999.

Full list of publications