Imidacloprid is a neonicotinoid, which is a class of neuro-active insecticides modeled after nicotine. A patented chemical, Imidacloprid is manufactured by Bayer Cropscience (part of Bayer AG) and sold under a variety of trade names including Kohinor, Admire, Advantage, Gaucho, Merit, Confidor, Hachikusan, Premise, Prothor, and Winner. It is marketed as pest control, seed treatment, an insecticide spray, termite control, flea control, and a systemic insecticide.
Studies on rats indicate that the thyroid is particularly sensitive to Imidacloprid, causing thyroid lesions.
In France, its use (as Gaucho) has become controversial in terms of a possible link to derangement of behavior in domesticated honeybees. See Imidacloprid effects on bee population. In relation to this, Germany has banned seed treatment related to neonicotinoids, in May 2008, due to negative effects upon bee colonies.
On January 26, 2005, the Federal Register notes the establishment of the '(Pesticide Tolerances for) Emergency Exemptions' for Imidacloprid. It use was granted to Hawaii (for the) use (of) this pesticide on bananas(,) and the States of Minnesota, Nebraska, and North Dakota to use this pesticide on sunflower.
Imidacloprid has low vapor pressure. The chemical breaks down to inorganic molecules by both photolysis and microbial action, in the air and with a half-life of 30 days in water and 27 days in soil anaerobically. Although it is not "persistent" in the technical sense since it does degrade, it can have a half-life in soil under aerobic conditions of as long as 997 days, which is the cause of the concern over possible water contamination as it gradually leaches out of a hypothetical soil reservoir. The manufacturer maintains that, when applied according to instructions, such long-term contamination is only found as the result of "repetitive application over several years" and spread to beneficial insect populations is minimal. In the body, 96% of the chemical is eliminated within 48 hours; the most important degradation product in the body is 6-chloronicotinic acid, another nicotinic neurotoxin with similar properties. Imidacloprid has, however, been reported to degrade into toxic, persistent, 2-chloropyridine.
Animal toxicity is similar to that of the parent compound, nicotine; fatigue, twitching, cramps, and weakness leading to asphyxia. The oral LD50 of imidacloprid is 450 mg/kg body weight in rats and 131 mg/kg in mice; the 24-hour dermal LD50 in rats is greater than >5000 mg/kg. It is not irritating to eyes or skin in rabbits and guinea pigs (although some commercial preparations contain clay as an inert ingredient, which may be an irritant). The acute inhalation LD50 in rats was not reached at the greatest attainable concentrations, 69 milligrams per cubic meter of air as an aerosol, and 5,323 mg/m³ of air as a dust. In rats subjected to a two year feeding study, no observable effect was seen at 100 parts per million (ppm). At 300 ppm females showed decreased body weight gain and males showed increased thyroid lesions, while females showed increased thyroid lesions at 900 ppm. In a one year feeding study in dogs, no observable effect was seen at 1,250 ppm, while levels up to 2,500 ppm led to hypercholesterolemia and elevated liver cytochrome p-450 measurements. Reproductive studies in rats resulted in no observable effect at 100 ppm and decreased pup weight at 250 ppm; developmental toxicity studies in rats showed no observable effect at 30 (mg/kg)/day and skeletal anomalies at 100 (mg/kg)/day, while in rabbits no observable effect was detected at 24 (mg/kg)/day and skeletal abnormalities at 72 (mg/kg)/day. Imidacloprid was negative for mutagenicity in 21 out of 23 different laboratory tests, but was positive for chromosomal changes in human lymphocytes and for genotoxicity in CHO cells. No carcinogenicity was seen in rats fed up to 1,800 mg/kg of imidacloprid for two years.
When used for seed treatments, it is sold under the trade names Akteur, Amigo, Baytan Secur, Chinook, El Hombre, Escocet, Gaucho, Gaucho Blé, Gaucho CS, Gaucho Maícero, Gaucho MZ, Gaucho Orge, Gaucho Primo, Gaucho T, Gaucho MT, Gaucho XT, Genesis, Faibel, Ferial Blé, Férial Orge, Imprimo, Manta Plus, Monceren Extra, Monceren G, Monceren GT, Montur, Prestige, Prestige M, Raxil Secur, Seed-one, Sibutol Secur, Yunta and Zorro FS 236.
When used on citrus, coffee, cotton, fruits, grapes, potatoes, rice, soybeans, sugarcane, tobacco and vegetables as an insecticide spray, it is sold under the trade names Admire, Confidor, Connect, Evidence, Leverage, Muralla, Provado and Trimax.
It is marketed as Premise for termite control and Advantage in the US and Europe for flea control on pets. It is also sold under the trade names Merit, Admire, Confidor and Winner, as well as Hachikusan (in Japan).
12.5 to 25 g of pure Imidacloprid may be mixed with 15 L (4 US gallons) of water to cover 3 linear meters (10 feet) for purposes of treating subterranean termites.
Seed applied insecticides are often used to deal with numerous insects as they are easy to use and comparable in cost to most traditional insecticides used at sowing time. Some also indicate that it might be better for the environment because less chemical is required than for broadcast or banded applications, or at least because less chemical is sprayed in the air. However, some note that the use of seed-applied insecticides at each season implies the chemical is used whether there is need to fight insects or not.
Imidacloprid is receiving increased attention as a possible factor in Colony Collapse Disorder, a mysterious condition that causes sudden death of honey bee populations. Mass die-offs of bees threaten pollination of food crops in the USA and Europe.