This summer’s heatwave may have been bad for UK bumblebees | Science and technology news

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This summer’s heatwave may have been bad for Britain’s bumblebees, according to a new analysis examining long-dead collections of bees kept in museums.

Bumblebees have endured stress for nearly a century, possibly due to hotter, wetter conditions, research shows, but new DNA techniques may help focus future conservation efforts.

Researchers from Imperial College London and the Natural History Museum have teamed up with four other Scottish and English museums to analyze their bumblebee collections and look for body shape variations.

When bumblebees are stressed, it affects their developing offspring. Their bodies—particularly wings—become asymmetrical. By correlating the degree of asymmetry in four bumblebee species with the past 120 years of climate records, the researchers discovered that stress appears to be related to climatic conditions.

“When the conditions were warm and relatively wet, the stress was higher,” says Dr. Richard Gill from Imperial College London, who led the study.

Picture:
Image: Ashleigh Whiffin

Climate change was already known to affect the geographic distribution of some bumblebees, but this is the first study showing its potential impact on insects that lived in the past.

“Museum specimens are almost like little time machines tracking this stress,” says Dr. Gil.

The researchers found that stress levels for the species they studied were lowest around 1925. Since then there has been a general increase in stress levels – with higher levels in years that have been both wetter and warmer than average.

Why things started to change around 1925 isn’t clear, according to the research team. One possibility is that it is related to changes in agricultural practices and use of pesticides, which are known to have led to insect declines in the late 20th century.

This is pure speculation, stresses Dr. Gil. However, a parallel study also published today could help pinpoint threats to bumblebees and broader insect die-offs by extracting DNA from museum specimens.

Professor Ian Barnes of the Natural History Museum has been able to borrow genetic data from dry, dusty bumblebee collections that have been used to study ancient DNA from people like Neanderthals and woolly mammoths.

Taking just a single leg from about 100 bee samples, his team was able to reconstruct genomes from long-dead bees — an extremely valuable tool compared to the genetic code of living bees today.

“A genome represents such a large amount of information about a past situation,” says Prof. Barnes.

Image: Richard Gil
Picture:
Image: Richard Gil

By matching historical data on things like climate, pesticide use and land-use changes with the genetics of the bees at that time, the researchers can see how bee populations responded or determine whether certain species were more susceptible to change than others.

“We can look for changes in diversity or signals of adaptation,” says Dr. Gil. “It might reveal things that we can’t see on the outside of a bee.”

Getting a picture of how bees have dealt with stress in the past could help focus conservation efforts in the future, the researchers say.

The work also shows how important museums are for forward-looking research.

“These museums all have secrets, it’s just a matter of revealing them,” says Dr. Gil.



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