Neurotoxicity of Neonicotinoids

Abstract Neonicotinoids are the most important new class of synthetic insecticides used in plant and animal health over the last decade to control sucking insects. The main marketed neonicotinoids are imidacloprid, thiamethoxam, clothianidin, thiacloprid, dinotefuran, acetamiprid, nitenpyram and sulfoxaflor. Neonicotinoids act as selective agonist at nicotinic acetylcholine receptors (nAChRs) in a very different way than nicotine which confers selectivity, binding more strongly to, insect than mammalian. This chapter describes the neurotoxicity in mammals and insects, and presents a series of acute neurotoxicity studies performed with imidacloprid, acetamiprid, thiamethoxam and thiacloprid. Moreover, subacute and subchronic neurotoxicity studies were described for imidacloprid, and imidacloprid and acetamiprid, respectively. Developmental neurotoxicity studies were also presented for imidacloprid and acetamiprid. The neurotoxicity was describe for target (insects) and non-target (insect pollinators) species. The latter is an issue highly controversial since neonicotinoids pose “high acute” risks for bees. Sublethal concentrations of neonicotinoids alter the behavior of social bees, reduce survival of entire colonies, and impair the olfactory memory and learning capacity of honeybees and orientation and foraging activity. The EFSA (2013) published three scientific opinion on the risks posed by the neonicotinoids clothianidin, thiamethoxam and imidacloprid as regards the risk to bees from the uses as seed treatments and granules. Finally, this review present clinical signs of animal intoxicated by imidacloprin in particular for the dogs and different cases reports of human poisoning produced by imidacloprid and thiacloprid. A subacute neonicotinoid intoxication through daily consumption of contaminated food is also described.