Bees' ability to forage for pollen is hampered by long-term exposure to a neonicotinoid pesticide, researchers behind a new study found.

Conducted by Nigel Raine of the University of Guelph and Richard Gill of Imperial College London, the study shows how long-term pesticide exposure affects bees' day-to-day behavior, including pollen collection and which flowers worker bees choose to visit.

"Bees have to learn many things about their environment, including how to collect pollen from flowers," Raine said in a news release. "Exposure to this neonicotinoid pesticide seems to prevent bees from being able to learn these essential skills."

This follows a recent study called "Gardeners Beware 2014" - described in Nature World News - that found that nearly 51 percent of garden plants purchased at big-name retailers in 18 cities in the United States and Canada contain the pesticide neonicotinoid - which has been frequently tied to massive declines in bee populations.

President Barack Obama is even attempting to solve the mystery of the declining honeybee populations with his "pollinator plan," which designated a team of experts to come up with a strategy to save this dying species.

In this study, the researchers fitted not honeybees, but bumblebees, with tiny radio frequency tags to track when individual bees left and returned to the colony, how much pollen they collected and from which flowers.

Bees from untreated colonies got better at collecting pollen as they learned to forage. But bees exposed to neonicotinoid insecticides became less successful over time at collecting pollen, and colonies even sent out more foragers to try to compensate for the lack of pollen.

"Although pesticide exposure has been implicated as a possible cause for bee decline, until now we had limited understanding of the risk these chemicals pose, especially how it affects natural foraging behaviour," Raine said.

Neonicotinoids make up about 30 percent of the global pesticide market, and so the researchers suggest reforming pesticide regulations, including adding bumblebees and solitary bees to risk assessments that currently cover only honeybees.

The findings were published in the journal Functional Ecology.