Common Pesticide Makes Honey Bees into Picky Eaters: New Study


For years now, beekeepers around the world have been concerned about the widespread use of agricultural pesticides, and specifically imidacloprid, which has been banned from some crops in Europe in an attempt to protect honeybees. Now, a UC San Diego study published in the Journal of Experimental Biology suggests that beekeepers’ concerns are justified.

James Nieh, a professor of biology at University of California San Diego, headed the research project with graduate student Daren Eiri as first author of the report. The study was funded by the North American Pollinator Protection Campaign and the National Science Foundation.

Nieh and Eiri were interested in the impact on bees of the class of pesticides known as neonicotinoids, as part of on-going research attempts to identify the cause of colony collapse disorder – the “disappearing bees” syndrome that has threatened the honeybees population since 2006 – and focussed their attention specifically on imidacloprid, a widely used chemical “known to affect bee learning and memory.”

The two biologists found in their experiments that honey bees treated with a small, single dose of imidacloprid, comparable to what they would receive in nectar, became “picky eaters.”

“In other words, the bees preferred to only feed on sweeter nectar and refused nectars of lower sweetness that they would normally feed on and that would have provided important sustenance for the colony,” said Eiri. “In addition, bees typically recruit their nestmates to good food with waggle dances, and we discovered that the treated bees also danced less.”

In some cases, the bees stopped dancing completely.

And when bees become “picky eaters,” going for only the sweetest nectar, the total amount of stores brought into the hiveis naturally reduced – meaning, potentially, the difference between colony survival and starvation. Beekeepers know, too, that queens tend to produce more brood in times of ample food supply, so don’t you have to wonder what effect the lower stores would have on reproduction and colony build-up?

The bottom line, says Nieh, is that “exposure to amounts of pesticide formerly considered safe may negatively affect the health of honey bee colonies.”

Press release: Commonly Used Pesticide Turns Honey Bees into ‘Picky Eaters’

Photo: Hives of north Alberta