Bees lethargic on neonicotinoids

Queen bees exposed to nicotine-based insecticides become less active and lay fewer eggs than those not so exposed, according to a story by Dan Gunderson for Minnesota Public Radio News citing a University of Minnesota study made public on Friday.

The link between neonicotinoid insecticides and the drop in bee numbers has been known for several years, but it’s still not well understood. The study, published in the journal Scientific Reports, is said to fill in some of the gaps in that knowledge.

Queen bees exposed to neonicotinoid insecticide became lethargic and laid fewer eggs, said Judy Wu-Smart, who’s now an assistant professor at the University of Nebraska-Lincoln, but who did this research while a graduate student at the University of Minnesota.

“We didn’t know that the queens could be impacted so readily; we didn’t know that at even lower doses that these queens would have reduced egg laying,” she said.

Wu-Smart and her colleagues found that it wasn’t only queens who were affected by insecticide exposure. Worker bees were also less active; so they did a poor job of removing pests like varroa mites from the colony, and they collected less pollen.

“The pollen I think is an important aspect particularly because that’s what’s necessary for brood production,” she said.

The study also showed the difficulties in understanding the complex effect of insecticides on bees.

When the chemicals are applied to seeds or soil, the plant absorbs them along with water and nutrients. So when a soybean aphid or potato beetle bites a leaf, they get a dose of insecticide, which is designed to impair brain activity and kill them. It’s an efficient pest control.

But the insecticide also affects beneficial insects such as bees that feed on plant flowers.

Bees exposed to low amounts aren’t killed, but their behavior changes in ways consistent with brain impairment, which would explain why queens lay fewer eggs and the colony collects less food for young bees.

The full story is at: http://www.postbulletin.com/news/local/u-study-nicotine-based-insecticides-inhibit-bee-reproduction/article_35fb87d2-a07b-529d-bb81-d8c6fa01f3bc.html