We’ve known for quite a while that pesticides can be detrimental to a bee’s health. Just as the public began to notice this decline in bee populations, however, the chemicals took off as a popular plant maintenance technique. Yet know one really knew the specific cause for the deaths. Now researchers from Vanderbilt University might have found that correlation.
Research led by Doug McMahon, Stevenson Chair of Biological Sciences, sought to explore the connection. In their study, “Neonicotinoids disrupt circadian rhythms and sleep in honey bees” which was published in the journal Scientific Reports, the Vandy team found that when bees pollinate plants which have been covered in certain pesticides that contain nonlethal levels of neonicotinoids, a chemical resembling nicotine, the bees are losing sleep, causing a disruption of their circadian rhythm. This, in turn, can cause the honey bees to lose their sense of time and navigation, which leads to broader stress within highly social bee populations and lower hive survival rates.
“Neonicotinoids are nicotine like chemicals,” says McMahon. “They attach to, and stimulate, neurochemical receptors that are responsible for communication of signals within the brain. So they artificially overstimulated these receptors.”
In a series of experiments that exposed the bees to constant light, constant darkness and light, and dark cycles, the researchers found a surprising mechanism by which the pesticide acts. Constant light conditions disrupted the circadian rhythm in 28% of bees. When levels of pesticides common in flower nectar and pollen were added to the bee’s food supply, the number jumped to up to 46%.