Disappearing bees mystery: Boffins finger regicide pesticides
Buzz-buggers say neo-Nick O'Teen makes drones get lost
Boffins investigating the ongoing mystery of disappearing bees have linked commonly used pesticides to their decline.
A moss carder bumblebee. Credit: David Goulson
Two studies, one by UK researchers and one in France, have suggested that neonicotinoid insecticides, which have been in use since the early 1990s, could be harming bee populations worldwide.
It's not the first time that scientists have proposed that pesticides could be partially to blame for the disappearing bees, but it's been unclear exactly how the chemicals are damaging the fuzzy flower-furtlers.
In the last few years, many boffin-years have been devoted to the mysterious disappearance of bees, often referred to as Colony Collapse Disorder, as honeybee populations have been decimated and bumblebee species have also gone missing.
“Some bumblebee species have declined hugely. For example in North America, several bumblebee species which used to be common have more or less disappeared from the entire continent. In the U.K., three species have gone extinct,” Dave Goulson of the University of Stirling, co-author on the British study, said in a tinned statement.
Goulson and his colleagues exposed developing bumblebee colonies to a neonicotinoid called imidacloprid in doses comparable to what they might find in the wild. They found that the colonies were around ten per cent smaller than hives that weren't exposed.
The treated colonies also produced 85 per cent fewer queen bees, meaning far fewer bee-leaders to go off and set up new colonies of their own.
“Bumblebees pollinate many of our crops and wild flowers. The use of neonicotinoid pesticides on flowering crops clearly poses a threat to their health, and urgently needs to be re-evaluated,” said Goulson.
The French study stuck tiny RFID chips on to honeybees so they could track them as they buzzed in and out of their hives. The boffins, based at the French National Institute for Agricultural Research (INRA), found that bees they had blasted with a sublethal dose of the neonicotinoid thiamethoxam got disorientated and couldn't find their way home.
Honeybees have a homing ability that lets them navigate back to their hives, which the researchers reckon was messed up by the pesticide. The lost honeybees were two to three times more likely to die outside the nest, pushing populations down to levels that would be difficult to recover from.
"Our study raises important issues regarding pesticide authorization procedures. So far, they mostly require manufacturers to ensure that doses encountered on the field do not kill bees, but they basically ignore the consequences of doses that do not kill them but may cause behavioural difficulties," said study author Mikaël Henry of INRA.
Both studies are to be published in this month's Science journal.
Neonicotinoid pesticides have long been lambasted by environmental groups that think they are harmful to wildlife and plant life, despite the fact that they became popular because of their perceived non-toxicity.
Partial bans have been instituted in some countries, and scientists have previously suggested a link between the pesticides and the decline in bees, although most don't think that's the only reason the bees are dying out.
The US' Environmental Protection Agency notes on its website that France, Germany, Italy and Slovenia have all instituted partial or temporary bans on neonicotinoids over fears of their effect on bees, but adds "to the EPA's knowledge, none of the incidents that led to suspensions have been associated with Colony Collapse Disorder".
Scientists are also in two minds about the potential harm of neonicotinoids, with some claiming that the actual doses used in the wild aren't enough to do any bee-related damage. ®