Neonicotinoid insecticides like Imidacloprid, Clothianidin, Thiamethoxam, and Thiacloprid affect the amount of sleep both bumblebees (Bombus terrestris) and fruit flies (Drosophila melanogaster) ingest, according to two new studies by researchers at the University of Bristol.
“The neonicotinoids we tested had a huge impact on how much flies and bees sleep,” said Dr. Kiah Tasman, a researcher in the Department of Physiology, Pharmacology and Neuroscience at Bristol University.
“When an insect was exposed to an amount similar to what might occur on a farm where the pesticide was applied, it slept less and its daily behavioral rhythms were no longer synchronized with the normal 24-hour cycle of day and night. ”
In the Bumblebee study, exposure to the field-relevant concentration of the neonicotinoid insecticide imidacloprid reduced foraging activity, locomotion and foraging rhythm.
Shredders also showed an increase in daytime sleep and an increase in the proportion of nighttime activity.
In the fruit fly study, the authors tested the effects of four neonicotinoids – imidacloprid, clothianidin, thiamethoxam, and thiacloprid – on memory, circadian rhythms, and sleep.
Field-relevant concentrations of imidacloprid, clothianidin and thiamethoxam disrupted learning, behavioral rhythms and sleep, while thiacloprid exposure only affected sleep.
“Timing is important to knowing when to be awake looking for food, and it looked like these drugged insects couldn’t sleep,” said Dr. James Hodge, researcher in the Department of Physiology, Pharmacology and Neuroscience at the University of Bristol.
“We know that good sleep is just as important to insects as it is to humans, to their health and to creating lasting memories.”
“Bees and flies have similar structures in their brains, and this suggests one reason why these drugs are so bad for bees that they prevent the bees from sleeping properly and then learn where food is around them” , added Dr. Sean added Rands, a researcher at the University of Bristol’s School of Biological Sciences.
The results appear in two articles in the journal iScience and the journal Scientific Reports.
Kiah Tasman et al. 2020. The neonicotinoid insecticide Imidacloprid disrupts the bumblebee feeding rhythms and sleep. iScience 23 (12): 101827; doi: 10.1016 / j.isci.2020.101827
K. Tasman et al. 2020. Neonicotinoids disrupt memory, circadian behavior and sleep. Sci Rep. 11, 2061; doi: 10.1038 / s41598-021-81548-2