An Insect's Fear of Hungry Predators Limits the Beneficial Impacts of Climate Change

Climate change may impact insect distribution and abundance. But now, scientists have found another factor that may come into play as temperatures shift. They've discovered that insects' fear of their predators ultimately limits how fast they grow, which could be an important factor to take into account when monitoring how insects might react to climate change.

Animals, including insects, live in a constantly changing environment. For example, the fear of predators can drastically alter their behaviors, physiologies, growth and population dynamics. That's why scientists decided to take a closer look at how the fear of predators might impact insects.

Previous studies have shown that warming temperatures cause insects to eat more and growth faster. In this case, though, the scientists factored in fear, which typically lowers food consumption and growth rate. They then examined how fear plays into insects' response to warming temperatures.

The scientists brought damselflies into the lab and then measured how much they ate and grew at different temperatures. Then, they measured how much this changed when a fish predator was nearby. In the end, the researchers found that in the absence of fear, the damselflies ate more food and grew faster as the temperature increased. But when a fish predator was introduced, the damselflies ate about the same amount of food, but grew more slowly.

"In other words, it's less about temperature and more about the overall environmental conditions that shape the growth, survival and distribution of insects," said Lauren Culler, lead author of the new study, in a news release. "Studies that aim to predict the consequences of climate change on insect populations should consider additional factors that may ultimately limit growth and survival, such as the risk of being eaten by a predator."

The findings are published in the journal Oecologia.