"Thermal preference plasticity in ectotherms: Integrating temperature affinity and thermoregulation precision"
Gwenaëlle Deconninck, Nicolas Meyer, Hervé Colinet, and Sylvain Pincebourde: Read the article
When It Gets Too Hot, Insects Move Too: New Study on Thermal Preferences
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W hen I was growing up, I thought summers in Michigan were hot—that was until I moved to Texas. Every summer, I think about packing up and heading back North, or at least going on a short vacation to somewhere cooler, and who could blame me? When every summer is hotter than the last, who wouldn’t want to get away from the heat?
Turns out, I’m not alone. Animals don’t like the heat either. We all know birds migrate to cooler regions during the summer months to beat the heat, but did you know that many other animals, and even insects, try to avoid the heat too? Many insects change how they act when the temperature increases. They’ll actively search for cooler areas, like shady patches under leaves, cool soil layers, hidden spots inside fruit, or even into your air-conditioned house. They do all this to avoid temperatures that could kill them.
Unlike birds, which tend to migrate together regardless of age, insects go through radically different life stages from crawling larvae to winged adults. This raises an important question: do all stages respond to heat in the same way, or do these life stages face different challenges?
That’s what a new study by Deconninck and colleagues set out to investigate. Their research reveals that insects don’t just have a single “favorite” temperature. Instead, thermal preferences can shift depending on the insect’s life stage (i.e. larva or adult) and even based on the temperatures their parents experienced. This flexibility suggests that insects might be more adaptable to extreme temperatures than we previously thought, a possibility that has big implications in a warming world.
The researchers found that Drosophila melanogaster, the common fruit fly, changes how it avoids heat stress as it develops, using different strategies at each life stage. Adults, thanks to their wings, can fly off in search of a cooler spot when it gets too hot. Larvae, however, have limited mobility and must deal with the temperatures they’re exposed to. So, while adults rely on moving around to regulate their temperature, referred to as behavioral thermoregulation, larvae may have to adapt physiologically to survive high temperatures.
The researchers also discovered that these thermal preferences don’t stay the same over an insect’s lifetime. A single fly’s preferred temperature can shift as it grows and even change across generations. In this study, when flies were exposed to daily temperature fluctuations for two generations, the third generation consistently chose to move toward cooler areas when given a choice between temperatures. This behavior likely helped them avoid dangerously high temperatures that can cause stress or even death.
For insects that spread disease or damage crops, how insects respond to heat stress throughout their lifetime and across generations matters a lot as our world gets hotter. Will mosquitoes become an even bigger threat to human health? Will pests invade new regions and contribute to food scarcity? This study shows that instead of just asking how hot is too hot for an insect to survive, we need to ask how well it can adapt to beat the heat. The answers could change how we predict pest outbreaks, disease spread, and how we manage these insects in an ever-warmer world. So next time you think about escaping the summer heat, remember that insects are doing the same, and their ability to adapt could reshape ecosystems, agriculture, and disease risks as our climate continues to warm.
Patrick Stillson is a USDA NIFA Postdoctoral Fellow in the Biology Department at Emory University, where his research investigates insect–microbe interactions and vector-borne plant pathogens. His work combines field ecology with genomics and transcriptomics to understand how microbial symbionts influence insect physiology, host abiotic stress response, and disease transmission.