5 June 2023

Habitat diversity helps insects address climate change

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Insects adapt to global warming with different energy management, a German research has found. Microhabitat diversity, which is crucial, is declining due to land-use changes

by Matteo Cavallito

 

Climate change affects the behaviors of terrestrial insects such as beetles, ants and butterflies by impacting the ecosystem services they provide to the soil. This is supported by research from the German Center for Integrated Biodiversity Research (iDiv) and Friedrich Schiller University in Jena. Forced to cope with increasing temperature extremes, specimens must reduce their activity or seek shelter in more suitable microhabitats, the diversification of which becomes decisive.

“A natural and diverse ecosystem offers many microhabitats that provide more favorable climate conditions as well as food for insects,” the scientists explain in a statement released by the German university. “But in the face of land-use changes, the diversity of these microhabitats is declining.” With obvious consequences for pollination, humus formation and general improvement in soil quality.

The investigation

To test the effects of increasing temperatures and microhabitat availability on terrestrial insect activity, scientists analyzed several isolated ecosystems by monitoring and altering environmental conditions such as light, nutrients and moisture. Species observed include the beetle species Carabus coriaceus, firebugs (Pyrrhocoris apterus), and house crickets (Acheta domesticus) for a total of 465 insects.

To accurately track their movements, the researchers developed a new tracking method based on radio frequency identification.

The researchers, in particular, “simulated heat extremes based on data that had been recorded by the Deutscher Wetterdienst (the German Meteorological Service, ed.) in 2018 and 2019,” the statement says. “Temperatures were reaching a maximum of 38.7 °C. They also added leaf litter from four different tree species to the EcoUnits – the litter was either separated or well-mixed.”

Different microhabitats mitigate heat effects

With the help of radio frequency sensing, researchers found that insects apply different strategies in response to extreme heat depending on microhabitat conditions. Under mixed litter conditions, the insects were able to significantly reduce their activity while saving energy and still finding enough food.

In environments with separate leaf litter, on the contrary, the insects had to move more to find food.

This increased their energy consumption, a phenomenon made even more risky by the extreme heat. The study, therefore, highlighted “the importance of diverse habitats and microhabitats,” said Myriam Hirt, researcher and co-author of the research. “In this way, the effects of extreme heat on insects can be significantly mitigated.”

Land consumption and pollution threaten insects

The study results take on important significance in a problematic context for insects. Researchers from Gutenberg University Mainz, Darmstadt Technical University and the Swiss Federal Institute for Forest, Snow and Landscape Research recently mentioned “an ongoing global collapse in insect populations (…) drastic consequences for ecosystem functioning and stability.”

Three factors in particular are reported to be facilitating the phenomenon: land use, invasion of different species, and climate change. Thus, “the combined effects on insect populations and communities can be more serious than the sum of the individual factors.”