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Neonicotinoids are a new class of insecticides chemically related to nicotine. The name literally means “new nicotine-like insecticides”. Like nicotine, the neonicotinoids act on certain kinds of receptors in the nerve synapse. They are much more toxic to invertebrates, like insects, than they are to mammals, birds and other higher organisms. Neonicotinoids share a common mode of action that affect the central nervous system of insects, resulting in paralysis and death.
One thing that has made neonicotinoid insecticides popular in pest control is their water solubility, which allows them to be applied to soil and be taken up by plants. Soil insecticide applications reduce the risks for insecticide drift from the target site, and for at least some beneficial insects on plants.
They include imidacloprid, acetamiprid, clothianidin, di-notefuran, nithiazine, thiacloprid and thiamethoxam.
Uncertainties prevail since their initial registration regarding the potential environmental fate and effects of neoni-cotinoid pesticides, particularly as they relate to pollinators. Studies conducted in the late 1990s suggest that neonico-tinic residues can accumulate in pollen and nectar of treated plants and represent a potential risk to pollinators. There is major concern that neonicotinic pesticides play a role in recent pollinator declines.
Neonicotinods can also be persistent in the environment, and when used as seed treatments, translocate to residues in pollen and nectar of treated plants.
New research points out potential toxicity to bees and other beneficial insects through low level contamination of nectar and pollen with neonicotinoid insecticides used in agriculture. Although the low level exposures do not normally kill bees directly, they may impact some bee’s ability to foraging for nectar, learn and remember where flowers are located, and possibly impair their ability to find their way home to the nest or hive.
In April 2013, the European Commission decided to introduce a 2-year moratorium in EU on the 3 neonicotinod compounds—clothianidin, imidacloprid, and thiameth-oxam—following reports by the European Food Safety Authority (EFSA) saying the substances pose an “acute risk” to honey bees essential to farming and natural ecosystems.