|
Neonicotinoids (sometimes shortened to neonics) are a class of neuro-active insecticides chemically similar to nicotine. In the 1980s Shell and in the 1990s Bayer started work on their development. The neonicotinoid family includes acetamiprid, clothianidin, imidacloprid, nitenpyram, nithiazine, thiacloprid and thiamethoxam. Imidacloprid is the most widely used insecticide in the world. Compared to organophosphate and carbamate insecticides neonicotinoids cause less toxicity in birds and mammals than insects. Some breakdown products are toxic.〔Tomizawa M, Casida JE. Neonicotinoid insecticide toxicology: mechanisms of selective action. Annu Rev Pharmacol Toxicol. 2005;45:247-68. PMID 15822177〕 In the late 1990s neonicotinoids came under increasing scrutiny over their environmental impacts.〔http://www.nytimes.com/2007/04/24/science/24bees.html?pagewanted=all&_r=0〕 Neonicotinoid use was linked in a range of studies to adverse ecological effects, including honey-bee colony collapse disorder (CCD) and loss of birds due to a reduction in insect populations. In 2013, the European Union and a few non EU countries restricted the use of certain neonicotinoids.〔 ("Nature Studies by Michael McCarthy: Have we learned nothing since 'Silent Spring'?" ) ''The Independent'' 7 January 2011 ("Do people know perfectly well what’s killing bees?" ) ''IO9.com'' 6 January 2011〕〔(Bees & Pesticides: Commission goes ahead with plan to better protect bees. ) 30 May 2013.〕 == History == The precursor to nithiazine was first synthesized by a chemist at Purdue University in 1970; Shell researchers found in screening that this precursor showed insecticide potential and refined it to develop nithiazine.〔 In 1984 nithiazine's mode of action was found to be as a postsynaptic acetylcholine receptor agonist, the same as nicotine. Nithiazine does not act as an acetylcholinesterase inhibitor,〔 in contrast to the organophosphate and carbamate insecticides. While nithiazine has the desired specificity (i.e. low mammalian toxicity), it is not photostable, that is, it breaks down in sunlight, and thus not commercially viable. In 1985, Bayer patented imidacloprid as the first commercial neonicotinoid.〔 During the late 1990s, primarily, imidacloprid became widely used. Beginning in the early 2000s, two other neonicotinoids, clothianidin and thiamethoxam entered the market. , virtually all corn planted in the United States was treated with one of these two insecticides and various fungicides.〔Erik Stokstad. (Pesticides Under Fire for Risks to Pollinators ). Science 340(6133):674-76. 10 May 2013: DOI: 10.1126/science.340.6133.674〕 , about a third of US soybean acreage was planted with neonicotinoid treated seeds, usually imidacloprid or thiamethoxam.〔US EPA. 15 October 2014. (Benefits of Neonicotinoid Seed Treatments to Soybean Production )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Neonicotinoid」の詳細全文を読む スポンサード リンク
|