Some bumblebees are not as busy as they could be, and a group of widely used pesticides known as neonicotinoids are to blame, a study published Tuesday suggests.
Bumblebees were fitted with tiny radio frequency tags for the study, which showed that long-term exposure to neonicotinoid pesticides debilitated a bee’s ability to forage for pollen, and even impacted which flowers the worker bees chose to visit.
This is important because “bees have to learn many things about their environment, including how to collect pollen from flowers,” said Nigel Raine, co-author of the study and a University of Guelph scientist.
Exposure to neonicotinoid pesticides seems to be preventing bees from being able to learn these essential skills, he said.
Richard Gill of Imperial College London was the other author of the study, published in the British Ecological Society’s journal Functional Ecology.
Neonicotinoid pesticides — the controversial insecticides that act on the nervous system and are lathered on corn and soy — have been in the news for months, and have been linked to unusually high honey bee deaths in Canada for the past two years.
The bee population has dropped by almost 35 per cent in recent years.
Bee farmers and environmentalists have been calling for a ban on these pesticides.
On Monday, Ontario announced that it is looking at restricting the use of neonicotinoids, requiring farmers and other commercial growers to apply for permits.
Raine said it is important to recognize that pesticide use may have different impacts on different bees. “Bumblebees may be much more sensitive to pesticide impacts as their colonies contain a few hundred workers at most, compared to tens of thousands in a honey bee colony,” he said.
The researchers fitted hundreds of bees with the tags in 2011 and monitored the movement of 260 for a month — when they left and returned to their colonies, how much pollen they collected, and from which flowers.
They discovered that bees from untreated colonies got better at collecting pollen as they learned to forage, but the bees exposed to neonicotinoids became less successful over time.
The study also showed that neonicotinoid-treated colonies compensated for a lack of pollen from individual bees by sending out more foragers.
“If pesticides are affecting the normal behaviour of individual bees, this could have serious knock-on consequences for the growth and survival of colonies,” explained Raine.
The result of this study may convince Ottawa to take the issue of pesticides seriously, said John Bennett of Sierra Club Canada.
“We have been saying that bee populations are drastically declining,” he said. “Ontario has now said it will go through licensing but Ottawa isn’t ready to take any action.”
In Guelph, Raine said pesticides aren’t the only problem bees face, “but if we can remove or mitigate their use, it would be a very good step from a bee conservation perspective.”