Thiamethoxam

Thiamethoxam is a systemic insecticide in the class of neonicotinoids. It has a broad spectrum of activity against many types of insects. Thiamethoxam is a systemic insecticide in the class of neonicotinoids. It has a broad spectrum of activity against many types of insects. Thiamethoxam was developed by Syngenta; a patent dispute arose with Bayer which already had patents covering other neonicotinoids including imidacloprid. In 2002 the dispute was settled, with Syngenta paying Bayer $120 million in exchange for worldwide rights to thiamethoxam. Thiamethoxam is a broad-spectrum, systemic insecticide, which means it is absorbed quickly by plants and transported to all of its parts, including pollen, where it acts to deter insect feeding. An insect can absorb it in its stomach after feeding, or through direct contact, including through its tracheal system. The compound gets in the way of information transfer between nerve cells by interfering with nicotinic acetylcholine receptors in the central nervous system, and eventually paralyzes the muscles of the insects.:17 Syngenta asserts that thiamethoxam improves plant vigor by triggering physiological reactions within the plant, which induce the expression of specific 'functional proteins' involved in various stress defense mechanisms of the plant allowing it to better cope under tough growing conditions, such as 'drought and heat stress leading to protein degradation, low pH, high soil salinity, free radicals from UV radiation, toxic levels of aluminum, wounding from pests, wind, hail, etc, virus attack'.:16 The selective toxicity of neonicotinoids like thiamethoxam for insects versus mammals is due to the higher sensitivity of insects' acetylcholine receptors. The Food and Agriculture Organization (FAO) of the U.N. assessed thiamethoxam as 'moderately hazardous to humans (WHO class III)', because it is harmful if swallowed. It found it to be no skin or eye irritant, and not mutagenic in any in vitro and in vivo toxicology tests.:20 FAO described thiamethoxam as non-toxic to fish, daphnia and algae, mildly toxic for birds, highly toxic to midges and acutely toxic for bees.:20 The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) classification is: 'Harmful if swallowed. Very toxic to aquatic life with long lasting effects'.:20 Sublethal doses of thiamethoxam metabolite clothianidin (0.05–2 ng/bee) have been known to cause reduced foraging activity since at least 1999, but this was quantified in 2012 by RFID tagged honeybees. Doses of equal or more than 0.5 ng/bee caused longer foraging flights. Thiamethoxam is approved for use in the US as an antimicrobial pesticide wood preservative and as a pesticide; it was first approved in 1999.:4 & 14 As of 2014, it is approved for use in a wide range of crops.