World's Most Common Insecticide May Not Significantly Impact Bees

It turns out that pesticides aren't the only problem that's impacting honey bee colonies. Researchers have found that the world's most common insecticide does not significantly harm honey bee colonies at real-world dosage levels.

The insecticide in question is called imidacloprid. It's just one of a broad class of insecticides called neonicotinoids, which are chemically derived from nicotine. In tobacco and other related plants, nicotine acts as a deterrent by poisoning would-be herbivores. While nicotine itself was once used as an insecticide, it has fallen out of favor because it is highly toxic to humans and breaks down rapidly in sunlight. Neonicotinoids have been engineered to address this issue.

In this latest study, the researchers fed honey bee colonies pollen dosed with imidacloprid. The team purposely constructed a worst-case scenario, even at lower exposure levels; they fed the colonies tainted food for up to 12 continuous weeks. This is a much longer exposure than bee colonies would experience in real world scenarios, because most crops do not bloom for such an extended period of time.

"A lot of attention has been paid to neonicotinoids, but there isn't a lot of field data. This study is among the first to address that gap," said Dennis vanEngelsdrop, an assistant professor of entomology at UMD who was not involved in the study, in a news release. "It's not surprising that higher levels will hurt insects. They're insecticides after all. But this study is saying that neonicotinoids probably aren't the sole culprit at lower, real-world doses."

While the insecticide may not be the sole culprit, then a combination of factors may be to blame. It's very possible that the insecticide exacerbates other problems, as well.

The findings are published in the journal PLOS One.

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