Neonicotinoids

Neonicotinoids are a class of neuro-active insecticides. The mode of action [Guide to pesticide modes of action http://www.dropdata.org/RPU/pesticides_MoA.htm#neonicatinoids] of neonicotinoids is similar to the natural insecticide nicotine, which acts on the central nervous system. In insects, neonicatinoids cause paralysis which leads to death, often within a few hours. However, they are much less toxic to mammals and under the WHO / EPA classification these compounds are placed toxicity class II or class III. Because the neonicotinoids block a specific neural pathway that is more abundant in insects than warm-blooded animals, these insecticides are selectively more toxic to insects than mammals.

They bind at a specific site (the postsynaptic nicotinic acetylcholine receptor), and there are no records of cross-resistance to the carbamate, organophosphate, or synthetic pyrethroid insecticides, thus making them important for management of insecticide resistance. As a group they are effective against sucking insects such as aphids, but also chewing insects such as Coleoptera and some Lepidoptera.

Imidacloprid is possibly the most widely used insecticide, both within the mode of action group and in the world-wide market. It is now applied against soil, seed, timber and animal pests as well as foliar treatments for crops including: cereals, cotton, grain legumes, potatoes [http://www.nationalpotatocouncil.org/NPC/p_documents/document_280607084102.pdf] , pome fruits, rice, turf and vegetables. It is systemic with particularly effective against sucking insects and has a long residual activity. The application rates for neonicotinoid insecticides are much lower than older, traditionally used insecticides.

Thiamethoxam's chemical structure is slightly different from other neonicotinoid insecticides, making it highly water soluble and thus it is readily translocated in plant tissue.

In 2001, the US Patent and Trademark Office ruled in favour of Syngenta when the company filed suit against Bayer to protect its patent on a class of neonicotinoid insecticides.

Environmental Impact

There is controversy over the role of neonicotinoids in relation to pesticide toxicity to bees and imidacloprid effects on bee population. Neonicotinoids have been strictly limited in France since the 1990s, when they were implicated in a mass die-off of the bee population. It is believed by some to account for worker bees neglecting to provide food for eggs and larvae, and for a breakdown of the bees' navigational abilities and possibly leading to what has become generally known as Colony Collapse Disorder, which is usually associated with the mite pest "Varroa destructor" [Colony Collapse Disorder http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/04/01/nbees01.xml] [Mysterious Bee Deaths Linked to Pesticides http://www.livescience.com/animals/070615_ap_bee_trouble.html] .

Germany has banned seed treatment related Neonicotinoids, in May 2008, due to negative affects upon bee colonies. Bee keepers suffered a severe decline linked to the use of clothianidin in the Baden-Württemberg region of Germany [Germany bans pesticides linked to bee colony collapse http://www.guardian.co.uk/environment/2008/may/23/wildlife.endangeredspecies] , allegedly connected to a failure to apply a 'glue' agent that affixes the compound to the coats of seeds. The manufacturer maintains that without the fixative agent, the compound drifted into the environment from sown rapeseed and sweetcorn and then affected the honeybees.

Active Substances

Available neonicotinoid insecticides:
*acetamiprid
*clothianidin
*imidacloprid
*nitenpyram
*thiacloprid
*thiamethoxam
*dinotefuran

References

More External Links on Bee Deaths

* [http://www.wcsh6.com/news/article.aspx?storyid=57155 Blueberry Growers To Pay More For Bees]
* [http://www.thetimesonline.com/articles/2007/04/07/updates/breaking_news/doc46167add8cafc393728577.txt Disappearing bees stump beekeepers]
* [http://www.ktvb.com/news/localnews/stories/ktvbn-apr0507-bees.368f640c.html Where have all the bees gone?]
* [http://www.heraldtribune.com/apps/pbcs.dll/article?AID=/20070406/NEWS/704060356 Mysterious disease killing honey bees accelerates]