U of I Researchers Show How Honey Bees Tolerate Pesticides

Scientists at the University of Illinois at Urbana–Champaign (U of I) revealed the molecular mechanism on how enzymes in the honey bee gut detoxify pesticides that kill mites in the bee hive. According to the study leader May Berenbaum, previous studies already revealed that bees bring back agricultural chemicals in the bee hive in the form of contaminated pollen and nectar. For instance, acaricides, the chemical designed to kill termites have been used by beekeepers for more than 20 years. Though there is no concrete evidence that synthetic pesticides contribute to colony collapse disorder, it is clear that these chemicals aren't helpful for any insect. Thus, the researchers wanted to know how pollinators process toxins.

Baerenbaum and colleagues focused on cytochrome P450s, an enzyme known as an agent of detoxification in most air-breathing organisms. This enzyme has been known to help bees tolerate pyrethroid pesticides. So they observed the activity of the enzyme in the honey bee midgut and found that the enzyme can detoxify coumaphos, an organophosphate pesticide used to kill mites in bee hives. This suggests that the enzyme have no specialized function. It also implies that honey bees were "pre-adapted" to detoxify pyrethroid pesticides, which is similar to the structure of pyrethrins, the defensive compounds present in flowering plants.

"It appears that the same enzymes that helped the honey bees detoxify the pyrethrins in nature may also help them tolerate this relatively new pesticide exposure. The new findings should enhance efforts to develop mite control methods that are even less toxic to bees," Berenbaum said.

Read the research article at http://www.pnas.org/content/early/2011/07/20/1109535108.