Bees Not Harmed by Realistic Levels of Insecticide

A new field-based study from the University of Maryland shows that the world’s most common insecticide does not significantly harm honey bee colonies at real-world dosage levels.

The study, published recently in the journal PLOS ONE, looked at the effects of the insecticide imidacloprid on honey bee colonies over a three-year period. To see significant negative effects, including a sharp decrease in winter survival rates, the researchers had to expose the colonies to at least four times as much insecticide encountered under normal circumstances. At 20 times the normal exposure levels, the colonies experienced more severe consequences.

The study does not completely absolve imidacloprid of a causative role in honey bee colony declines. Rather, the results indicate that insecticides are but one of many factors causing trouble for the world’s honey bee populations.

“Everyone is pointing the finger at these insecticides. If you pull up a search on the internet, that’s practically all anyone is talking about,” said Galen Dively, emeritus professor of entomology at UMD and lead author of the study. “This paper says ‘no,’ it’s not the sole cause. It contributes, but there is a bigger picture.” S