Science: Impact of neonicotinoids on bees

Neonicotinoids disrupt the internal clock of bees, impacting many biological processes and behaviors

Honey bees are essential pollinators in ecosystems and agriculture, but their numbers have declined dramatically over the past three decades . This observed decline in pollinator populations is a priori linked to many factors such as habitat loss, climate change, increased vulnerability to diseases and pests and the use of pesticides. Regarding this last point, a family of substances attracts particular attention: neonicotinoids . Indeed, the exposure of colonies to sublethal doses (lower than lethal doses) is associated with a reduction in the survival of bee hives. This is explained by the chemical structure of neonicotinoids, nicotinic receptor agonists for acetylcholine, a major neurotransmitter in the nervous system.

Honey bees are very dependent on the circadian rhythm , that is to say the 24-hour cycle which allows the regulation of many biological functions such as orientation, foraging or even sleep and learning processes. and memory. However, the neurons of circadian clocks precisely receive light information via cholinergic signaling. They therefore constitute potential targets for neonicotinoids. This group of substances has been shown to interfere with bees' ability to navigate, as well as their learning and memorization process.. However, the underlying mechanisms remain unknown for the moment, even if these complex behaviors are strongly regulated by the internal clock and sleep (itself dependent on the circadian rhythm).

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