Imidacloprid effects on bees

Imidacloprid is a nicotine-derived systemic insecticide, belonging to a group of pesticides called neonicotinoids. Although it is off patent, the primary producer of imidacloprid is the German chemical firm Bayer CropScience. The trade names for imidacloprid include Gaucho, Admire, Merit, Advantage, Confidor, Provado, and Winner. Imidacloprid is a neurotoxin that is selectively toxic to insects relative to vertebrates and most non-insect invertebrates. It acts as an agonist on the postsynaptic nicotinic acetylcholine receptors of motor neurones in insects. This interaction results in convulsions, paralysis, and eventually death of the poisoned insect. It is effective on contact and via stomach action. Because imidacloprid binds much more strongly to insect neuron receptors than to mammal neuron receptors, this insecticide is selectively more toxic to insects than mammals. As a systemic pesticide, imidacloprid translocates or moves readily in the xylem of plants from the soil into the leaves, fruit, flowers, pollen, nectar, and guttation fluid of plants. Bees may be exposed to imidacloprid when they feed on the nectar, pollen, and guttation fluid of imidacloprid-treated plants.

Experts believe that imidacloprid is one of many possible causes of bee decline and the recent bee malady termed colony collapse disorder (CCD). In 2011, according to the United States Department of Agriculture, no single factor alone is responsible for the malady, however honey bees are thought to possibly be affected by neonicotinoid chemicals existing as residues in the nectar and pollen which bees forage on. The scientists studying CCD have tested samples of pollen and have indicated findings of a broad range of substances, including insecticides, fungicides, and herbicides. They note that while the doses taken up by bees are not lethal, they are concerned about possible chronic problems caused by long-term exposure.

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