What are Neonicotinoids?
Neonicotinoids are a group of insecticides used on a wide range of crop types, to control a variety of pests, particularly sap-feeding insects, such as aphids and root-feeding grubs. In veterinary medicine, neonicotinoids are used for tick control and in flea collars for pets. Neonicontinoids can be classified into one of three chemical groups, the N- nitroguanidines (imidacloprid, thiamethoxam, clothianidin, and dinotefuran), nitromethylenes (nitenpyram) and N-cyanoamidines (acetamiprid and thiacloprid). [2] They are systemic pesticides which, unlike contact pesticides that remain on the surface of the treated parts of plants (e.g. leaves), are taken up by the plant and transported throughout the plant (leaves, flowers, roots, stems, as well as pollen and nectar). The mode of action of neonicotinoids derives from their high affinity for nicotine acetylcholine receptors (nAchRs) located within insects' central nervous system. Neonicotinoids work by opening the ion channels which allow the entry of Na + and Ca 2+ into cells causing excitation, trembling, paralysis, and death depending on dose and exposure time [3]. In vertebrates, neonicotinoid toxicity is considered low because of the relatively low affinity of the nAchRs and poor penetration of the blood- brain barrier, hence neonicotinoids are much more toxic to invertebrates, like insects, than they are to mammals, birds, and other higher organisms.
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