Researchers examining pesticides' effect on bees

Insecticides have been identified as a culprit in the mysterious colony collapse disorder affecting bee populations around the world. Vera Krischik, an associate professor of entomology at the University of Minnesota, is examining bees to determine the effect of pesticides, Kathleen Masterson of Harvest Public Media reports. "It's not an easy question to answer," Krischik said. "It was easy when you had a contact insecticide and you sprayed in on an insect and it died. The effect of poisoned food is just a complex issue." (Masterson photo: UM graduate student Judy Wu)

One of the insecticides being examined is clothianidin, which was banned in Germany in 2008 when "some clothianidin seed treatments didn't stick to the seed, and the pesticide dust killed a large number of bees," Masterson writes. Like many pesticides, clothianidin was registered conditionally with the Environmental Protection Agency in 2003, meaning Bayer, the company behind the chemical, had to conduct and submit follow-up studies. "With clothianidin, the EPA accepted a bee study that the maker Bayer submitted for its follow-up assessment," Masterson writes. However, not everyone agreed with the Bayer study.

"Basically, the researchers hired by Bayer set up different plots, some with poisoned plants and some with untreated plants," Masterson writes. "But Krischik said they let the bees roam in both plots." Krischik explained, "So then if you looked at the effects on bees, you had no idea what they foraged on. So that created the controversy that is this data that was out there, did it show anything, because the experimental design wasn't really getting at the question."

As we recently reported, pesticides may be only one piece of the puzzle of colony-collapse disorder. "It's not going to be one thing that is causing honeybee decline or causing bumblebee decline," Krischik said. "It's habitat destruction, loss of food resources, poor quality food, loss of just the place to put your nest for a bumblebee, viruses, fungal diseases. We happen to be looking at pesticide issues, not to say other issues aren't as important." (Read more)