Imidacloprid was first registered for use in the U.S. in 1992 and is
possibly the most widely used insecticide of the [Neonicotinoid Pesticides].
It has a wide range of target pests and sites, including soil, seed,
structural, pets, and foliar treatments in cotton, rice, cereals, peanuts,
potatoes, vegetables, pome fruits, pecans, and turf. It is a systemic with
long residual activity and particularly effective against sucking insects,
soil insects, whiteflies, termites, turf insects, and Colorado potato
beetle. Products are available in dusts, granules, seed dressings as
flowable slurry concentrates, soluble concentrates, suspension concentrates,
and wettable powders. The application rates for neonicotinoid insecticides
are *much lower* than older, traditionally used insecticides.

Because the neonicotinoids block a specific neuron pathway that is more
abundant in insects than warm-blooded animals, these insecticides are more
selectively toxic to insects than mammals. The most available toxicity data
of the neonicotinoids is with imidacloprid. These data indicate that it is
less toxic when absorbed by the skin or when inhaled compared to ingestion.
It causes minor eye reddening, but is non-irritating to the skin. Signs of
toxicity in rats include lethargy, respiratory disturbances, decreased
movement, staggering gait, occasional trembling, and spasms. 

There are *no accounts* of human poisoning, but signs and symptoms of
poisoning would be expected to be those similar for rats. A chronic toxicity
study showed that rats fed up to 1,800 ppm resulted in a No Observable
Effect Level (NOEL) of 100 ppm. The EPA categorizes imidacloprid as a "Group
E" (no evidence of carcinogenicity). In animals and humans, imidacloprid is
quickly and almost completely absorbed from the gastrointestinal tract, and
eliminated via urine and feces within 48 hours. Of the neonicotinoids,
imidacloprid is the most toxic to birds and fish. Both imidacloprid and
thiamethoxam are highly toxic to honeybees.

from
Pesticide Information Office, Florida Cooperative Extension Service,
Institute of Food and Agricultural Sciences, University of Florida. Original
publication date October 2005. Visit the EDIS Web Site at
http://edis.ifas.ufl.edu.

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