This summer’s heat wave could have been bad for British bumblebees | Scientific and technical news

This summer’s heatwave could have been bad for Britain’s bumblebees, according to a new analysis that studied collections of long-dead bees held in museums.

Bumblebees have endured nearly a century of stress, possibly due to warmer and wetter conditions, research shows, but new DNA techniques could 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 for variations in body shape.

When bumblebees are stressed, it impacts their developing offspring. Their bodies – the wings in particular – become asymmetrical. By correlating the level of asymmetry of four bumblebee species to climate records from the past 120 years, the researchers found that stress appears to be linked to climatic conditions.

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

Photo: Ashleigh Whifin
Photo: Ashleigh Whifin

Climate change was already known to impact the geographic distribution of some bumblebees, but this study is the first to show its potential impacts on insects living in the past.

“Museum specimens are almost like little time machines that keep up with this stress,” says Dr Gill.

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

Why things started to change around 1925 is unclear, according to the research team. One possibility is that it is linked to changes in agricultural practices and the use of pesticides that are known to have led to the decline of insects in the late 20th century.

This is pure speculation, says Dr. Gill. However, a parallel study also published today could help identify threats to bumblebees and wider insect decline by extracting DNA from museum specimens.

Borrowing techniques used to study the ancient DNA of Neanderthals and woolly mammoths, Professor Ian Barnes of the Natural History Museum was able to recover genetic data from collections of dry, dusty bumblebees.

By taking a single leg from around 100 bee specimens, his team was able to reconstruct the genomes of long-dead bees – an extremely valuable tool compared to the genetic code of bees alive today.

“A genome is such a huge amount of information about a past situation,” says Professor Barnes.

Photo: Richard Gill
Photo: Richard Gill

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

“We can look for changes in diversity or signals of adaptation,” says Dr. Gill. “It could reveal things we can’t see outside of a bee.”

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

The book also underlines the importance of museums for prospective research.

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

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