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Insects struggle to adjust to high temperatures

As increasingly frequent and more intense heat waves expose a wide range of animals to temperatures outside of their normal limits, an international team of scientists led by the University of Bristol has investigated more than 100 species of insects to clarify how these climatic changes will affect them. The analysis revealed that insects have weak ability to adjust their thermal capacities to withstand high temperatures, and are thus more susceptible to global warming than previously thought.

One way in which insects deal with extreme temperatures is through a process called acclimation, where previous thermal exposure extends their critical thermal limits. Acclimation usually triggers a series of physiological changes, such as the upregulation of heat shock proteins, and results in modifications of the phospholipid composition in their cell membranes. 

However, the scientists found that most insects have significant problems to do this effectively: for each 1°C shift in exposure, their limits were adjusted by only 0.092°C and 0.147°C respectively (a 10 and 15 percent compensation). However, juvenile insects appeared to be better able to acclimate, suggesting that there can be critical periods in development when experiencing heat waves may improve later resilience.

“As temperature extremes become more intense and frequent in our warming world, many insects will have to rely on shifting to new ranges or changing their behavior to cope, rather than being able to physiologically tolerate wider temperatures,” said study lead author Hester Weaving, an expert in Biology at the University of Bristol.

“Our comparative study identified some major gaps in understanding insect responses to climate change and we urge for more studies on species in underrepresented groups and locations.”

The scientists are currently investigating how the reproduction of insects is affected by exposure to extreme temperatures. Clarifying this aspect could turn out to be more important in predicting future distributions than measures of performance or survival.

The study is published in the journal Nature Communications.

By Andrei Ionescu, Staff Writer 

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