Common insecticide may not harm bumble bees

Investigators have found no effect of an insecticide called thiamethoxam on bumble bees that forage on flowering winter oilseed rape. Using realistic field conditions, the researchers treated seeds of oilseed rape with the insecticide and then grew the seeds into flowers. They established similar conditions with seeds not treated with thiamethoxam, and they placed bumble colonies adjacent to the fields.

The team observed no effects of thiamethoxam on bumble bees' colony size or forager activity.

"These data are from one treated and two control fields in an isolated landscape with limited alternative forage; however, high levels of exposure were identified with an average of 70% of the pollen in the treated colonies originating from the adjacent winter oilseed rape field," said Dr. Helen Thompson, lead author of the Pest Management Science study. "We consider these data add to the weight of evidence that, under field conditions, there are no effects of thiamethoxam use as a seed treatment on winter oilseed rape on bumble bee colony development or forager activity."