Pesticides Damage Bumblebees' Pollinating Skills -- And That Spells Trouble For Our Food

Shelley Hazen

Science has known for a while that pesticides aren't good for bees, and a new study is adding to the evidence, demonstrating for the first time that the chemicals affect bumblebees' ability to collect nectar and pollen.

And that is bad news for mankind. If bumblebees can't learn this skill, the insects can't fulfill their most crucial role in the ecosystem: pollinating crops and wild plants. And that could harm the food supply, the Canadian Press reported.

The pesticides that do the most damage to bumblebees are called neonicotinoids, which are found in an insecticide called thiamethoxam. The study into the effect of this pesticide on the insects was co-authored in Canada and the UK and led by University of Guelph professor Nigel Raine.

Previous studies have revealed that neonicotinoid pesticides change the areas of honeybees' brains that are associated with learning and memory, United Press International reported. Raine's study is the first to show that the chemicals also change the bumblebees foraging abilities.

The study proved this by experimenting with bumblebees exposed to low, realistic levels of the pesticides. Researchers found that these bumblebees collected more pollen, but they took more time to do it than the control group.

They believe the bees spent as much time collecting pollen as they did learning how to get it from more complex flower shapes. The conclusion is that the pesticides confused the bumblebees.

Bumblebees exposed to pesticides foraged differently and sought out different flowers than the control. The pesticides essentially made it difficult for them to attain the skills needed to extract pollen from some wildflowers, particularly those that had complex shapes.

Raine explained the significance of this finding in a statement.

"Bees rely on learning to locate flowers, track their profitability and work-out how best to efficiently extract nectar and pollen. If exposure to low levels of pesticide affects their ability to learn, bees may struggle to collect food and impair the essential pollination services they provide to both crops and wild plants."

The effect of pesticides on bumblebees also has more far-reaching implications. If their ability to learn and adapt to their environment is damaged, they are more vulnerable to changes in the environment. The study stressed more research is needed to determine the impact of all forms of pesticides on bumblebees and other pollinators.

The Canadian government has already clamped down on the use of neonicotinoid pesticides. They are the first country in North America to do so after their beekeepers lost half their hives in 2013 and 2014. The pesticides have already been banned in Europe and in Ontario, and farmers are fighting the restrictions.

Starting in June, the federal government will ban the use of pesticides not approved for sale. The new rules apply to the use of seeds treated with pesticides. Seed vendors must be licensed to sell them, although farmers can still buy chemically-treated seeds in the U.S.

Canadian farmers can't use them on half their land this year and on none of it next year; if they want to, they have to prove their soil is infested with crop-eating worms or other insects.

The reasoning behind this restriction of neonicotinoids is because of the way the chemicals contaminate plants and thus, bumblebees and other pollinators. Crop seeds are treated with the pesticide, which is "infused" in the plant as it grows. Chemical residue contaminates the nectar and pollen, which bees feed on.

According to Raine and his study, the pesticides seem to be doing more harm than good.

"Our results suggest that current levels of pesticide-exposure could be significantly affecting how bees are interacting with wild-plants, and impairing the crucial pollination services they provide that support healthy ecosystem function."

Another study already examined how caffeine affects bees: it turns them into caffeine addicts.

[Image via OljaS/Shutterstock]