Pesticides Linked to Insomnia in Bees

New research suggests that pesticides are preventing insects from following a healthy and regular sleep schedule, a consequence that could help to explain why some pollinating insects are disappearing from the wild.

A ground nesting bee pollinates a flower in New Hampshire. The species is one of 14 wild bee species identified in a 2019 study that are critical to pollinating fruits and vegetables across New England, but are on the decline. (University of New Hampshire/Molly Jacobson)

(CN) — Many common pesticides have long come under fire for their potentially hazardous side effects on humans and wildlife. Now, new research suggests that they also may be responsible for preventing insects from enjoying a decent night’s sleep.

It is no secret that of all the resources humankind has at its disposal, few are as beloved and crucial to our survival as sleep. Humans — as well as just about every other living mammal on the planet — desperately depend on sleep to keep their bodies healthy and their mind alert. Without it, the consequences can prove disastrous and even deadly.

Insects are no exception. While some insects can get by without entering a state of what we would classify as sleep — butterflies achieve rest by lowering their internal body temperatures each night — many depend on the rejuvenating power of sleep just as much as any human or mammal.

Experts therefore became concerned when they discovered that many common pesticides, which have already fallen under heavy scrutiny in recent years for their potentially damaging influence on the health of plants and wildlife, may come with another unfortunate side effect: they can keep insects from falling asleep.

In a pair of studies published Thursday in Scientific Reports by experts from the University of Bristol’s Schools of Physiology, Pharmacology and Neuroscience and Biological Sciences, researchers reveal that neonicotinoid insecticides, the most common type of insecticide that is used throughout the world, can make it almost impossible for insects exposed by the pesticide to maintain a regular sleep cycle.

Kiah Tasman, teaching associate at the university and lead author of Thursday’s studies, reports the researchers came to this conclusion by experimenting with bumblebees and fruit flies, two insects that rely on sleep to carry out their pollination duties effectively in the wild.

“The neonicotinoids we tested had a big effect on the amount of sleep taken by both flies and bees,” Tasman said with the release of the study. “If an insect was exposed to a similar amount as it might experience on a farm where the pesticide had been applied, it slept less, and its daily behavioral rhythms were knocked out of sync with the normal 24-hour cycle of day and night.”

Researchers suggest these pesticides can wreak havoc on an insect’s ability to sleep not by influencing the insect’s body, but through its mind. The studies report insects like flies depend on an internal clock that tells it when it is time to forage and eat, and when it is time to hunker down and rest. 

But in sufficiently concentrated amounts, neonicotinoids can essentially knock out that mental clock — leaving the insect with no way to accurately gauge when it is time to sleep.

The studies report the mental damage may also not stop there. Experts also found evidence that high enough amounts of neonicotinoids can destroy an insect’s ability to form memories, a consequence that could significantly hinder their ability to find reliable food sources.

Experts say these factors combined with others could begin to partially explain why so many insect pollinators have begun to disappear from the wild, a grave phenomenon that has only worsened in recent years.

Thursday’s studies, however, report that one thing is clear: these common pesticides can be devastating. With neonicotinoids currently banned in the European Union, and several neonicotinoids-containing products banned in the United States, experts stress that nations and policymakers around the world need to be acutely aware of the threat these chemicals can pose to insects and their delicate sleep schedules.

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