Pesticide-Induced Bee Insomnia
We all know what it feels like to have a few sleepless nights, and sometimes a few hours of sleep can feel worse than no sleep at all. There are so many over-the-counter sleep remedies these days, it is clear that in our fast-paced world many of us are having trouble getting the sleep we need.
But for honeybees, the results of sleep-deprivation can lead to deadlier outcomes. Their natural sleep-wake cycle, or circadian rhythms, when disturbed, can cause the bee to become confused and disoriented, even experiencing deadly outcomes like never making it back to the hive.
A few years ago, Douglas McMahon, a biological sciences professor at Vanderbilt University and Michael Tackenberg, a postdoctoral scholar, started studying honeybees and pesticides. They wanted to discover why some honeybees seem to get lost on their way back to the hive. According to their recent paper published in Scientific Reports, neonicotinoid pesticides accumulate in bees’ brains and disrupt their circadian rhythms, causing sleep-deprived honeybees to not make it back to the hive.
This unrelated 2:58-minute video What Is Killing the Bees? by PurdueExtensionEntm takes this problem to a worse degree, meaning death instead of insomnia:
Bees often rest for 8-9 hours daily when it is dark outside, and they are unable to go foraging. They also go through homeostasis, which means they can make up for lost sleep the following night. According to Sierra Club, bees use their biological clock to be present in front of a flower at the very moment it opens on a particular day.
Part of the study was that bees living in hives on the grounds of Vanderbilt University that had not been exposed to any pesticides were brought into the lab and put in individual test tubes. Two groups were established. One group ate only honey and powdered-sugar candy while the other group was given the same bee candy but with a small non-lethal dose of the neonicotinoids clothianidin and thiamethoxam added. The bees that ate the added pesticides only slept for half as long, and their brains showed a build up of pesticides when studied by the scientists.
In fact, McMahon said that it was after just three days of low-level exposure that the bees turned into relative insomniacs, staying awake well into the night. Further, he added, neonicotinoids are nicotine derivatives, so they interact with neurotransmitters in the bee’s brain and block important messaging.
Honeybees depend on visual cues to find their way back to the hive, when foraging close to home. If they go farther afield, they depend on their circadian clock in relation to where the sun is in the sky to navigate home. It’s like their internal compass. Neonicotinoid pesticides can disrupt this inner guidance system.
Kirsten Traynor, a research associate focused on honeybee societies at Arizona State University, would like to see future research that is more in alignment with circadian rhythm disruptions in a colony or a more natural environment instead of in test tubes in a lab. She was not surprised by the research results, adding that “neonics” also impair a bee’s memory and ability to learn, and cause bees not to process incoming nectar as quickly as they normally do, to turn it into honey.
Honeybees are not the only bee species affected by these pesticides. Bumblebees produce fewer queens when they are exposed, and this could be devastating to their survival because only the queen survives the winter to start reproducing the following spring. It is harder to track wild native bees, but they are also in decline and neonicotinoids are under scrutiny in association with this, so more baseline research is needed.
Despite all the research that shows these pesticides are dangerous for bees, the EPA has not reduced their usage although they are reviewing the two that are mentioned above as well as two others for their impact on pollinators, humans and water eco-systems. A ruling is expected in 2021. Thiamethoxam, clothianidin and imidacloprid were all banned by the European Union in 2013.
McMahon says that if a bee gets lost and doesn’t make it home, she usually won’t make it through the night. If she takes off for a day of foraging without getting enough sleep, she is exhausted, and chances are high she will get lost. These pesticides are harming bees, especially neurologically, even in smaller doses, as shown by this research.
You can read the official research paper here.
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