Question: Have you seen that insects’ behaviour has changed because of global warming?

Andrew Yool answered on 2 Jul 2020: last edited 2 Jul 2020 4:04 pm

Hi there.
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This might be one for Freya – I’m a marine scientist, and while I know a little bit about crustacean relatives of insects, I don’t think the lessons from that help much with your question.
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However, I can have a stab at an answer. A general point I’d make is that for ectothermic animals like insects (and crustaceans), their body temperature is governed by environmental temperature. So if it’s warmer, they’re warmer. While the rates of processes like growth, respiration, etc., in living organisms typically rise with temperature (which is why you can find cold animals warming themselves in the sun), they tend also to have an optimal temperature range. If they’re below this, rates are lower but survivable, but if they’re above this, things can go badly wrong physiologically. This optimal temperature differs for animals used to different temperatures, so tropical animals have a higher optimum than polar animals. So I would expect animals to try to respond to temperature change. That might be active behavioural change (e.g. hiding from high daytime temperatures for longer) or migration (e.g. moving to somewhere with a more optimal temperature. Or it might be more passive and ecological (e.g. insect populations may become less successful where it’s now too warm, and more successful where it warms up to their optimum). And on top of all that, animals can adapt to temperature change to some degree as well, shifting their optimum towards the changed environmental temperature – but no animal is infinitely adaptable.
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One final point about migration – one of the things that climate change will do is eliminate certain cold environments completely (polar locations, high altitudes). So even if an animal can migrate, it might find that there is nowhere it can migrate to where its optimum temperature occurs. Some animals will go extinct as a result, others may be able to adapt to the warmer temperatures, and possibly even evolve so that their optimum temperature keeps up with the environment. However, we’re changing the temperature of the Earth at a pace that’s fast, even for animals like insects that can have short generation times.
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Anyway, I’m not sure just how much this all applies to insects, but hopefully someone else will know. I hope this general answer is still useful to you, however.
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Thanks for a great question!
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Andrew