As the climate warms, scientific studies have already shown that species move north. But not all are capable of doing it.
A new study, published in Science, reveals that bumblebee species fail to relocate, lose ranges in the south and even disappear in some regions due to rapid global warming on a continental scale.
"It's happening right now, but actually the decline started decades ago," Jeremy Kerr, a researcher in the department of Biology at the University of Ottawa (Canada) and lead author of the work, tells Sinc.
In fact, in southern Europe and North America, the territory covered by these pollinators has decreased by about 300 kilometers on both continents.
To demonstrate how climate change affects these insects, Kerr and his colleagues developed a database of 423,000 geolocated observations (collected from private and museum collections) of 67 bumblebee species from Europe and North America between 2001 and 2010. The Scientists also compared the northward shift changes of bee species in recent decades with bumblebee activity from 1901 to 1974, when the climate was colder.
The results surprisingly show that bumblebees have not moved north in recent decades. During the same period, these pollinators disappeared from the southern and warmer areas, because they could not move to colder habitats.
"We couldn't see general trends that show that bumblebees are outgrowing rapid warming," says Kerr, who points out that other factors such as land use and pesticides are not significant contributing factors to reducing their populations.
Imminent extinction Although the study does not predict when some species of bumblebee will disappear, “what we do know for sure is that many species of bumblebee are already on the brink of extinction.
This is the case of the Bombus affinis species ”, the lead author of the study assures Sinc. According to the researcher, some could even be extinct because "they have not been seen for a while."
The work shows the vulnerability to climate change of these pollinators that play a key role in agriculture, as it reveals that their decline is rapid.
"In the case of many species, these will face a real risk of global extinction in the coming decades if current trends continue," warns Kerr. For the expert, the problem is due to the fact that bumblebees have evolved in cold conditions, and they seem to have quite a few problems with the heat.
In addition, "we have found a sign that this is really happening in an evolutionary sense: a close relative of the bumblebee species shares similar tolerances to temperatures," says the scientist who indicates that there is a new biological mechanism that explains how the species respond to changes based on their evolutionary past.
Saving bumblebees Before this panorama, researchers propose strategies to help bumblebee species establish colonies in areas further north.
"This is what we call assisted migration," reports the lead author, who adds that this would help these species maintain their geographic ranges and thus could reduce the risk of extinction.
In the hot areas of the south, scientists plan to identify and protect places that have colder microclimates and greater availability of water.
"It is possible to create these refuges, but we do not know with certainty if this would help to keep bumblebee populations in areas where, if they did not have shelter, they would become extinct," says the expert. Kerr recalls that "pollinators are essential for food security and for the economy, which will be affected by the widespread loss of these insects."