E isomer | |
Z isomer | |
Names | |
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Preferred IUPAC name {3-[(2-Chloro-1,3-thiazol-5-yl)methyl]-5-methyl-1,3,5-oxadiazinan-4-ylidene}nitramide | |
Other names CGA293343 | |
Identifiers | |
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3D model (JSmol) | |
8555232 | |
ChEBI |
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ChEMBL |
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ChemSpider | |
ECHA InfoCard | 100.102.703 |
EC Number |
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KEGG |
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PubChem CID | |
UNII |
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CompTox Dashboard (EPA) |
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Properties [1] | |
C8H10ClN5O3S | |
Molar mass | 291.71 g·mol−1 |
Density | 1.57 g/cm3 |
Melting point | 139.1 °C (282.4 °F; 412.2 K) |
4.1 g/L | |
log P | -0.13 |
Hazards [2] | |
GHS labelling: | |
Warning | |
H302, H410 | |
P264, P270, P273, P301+P312, P330, P391, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Thiamethoxam is the ISO common name [3] for a mixture of cis-trans isomers used as a systemic insecticide of the neonicotinoid class. It has a broad spectrum of activity against many types of insects and can be used as a seed dressing.
A 2018 review by the European Food Safety Authority (EFSA) concluded that most uses of neonicotinoid pesticides such as Thiamethoxam represent a risk to wild bees and honeybees. [4] [5] In 2022 the United States Environmental Protection Agency (EPA) concluded that Thiamethoxam is likely to adversely affect 77 percent of federally listed endangered or threatened species and 81 percent of critical habitats. [6] The pesticide has been banned for all outdoor use in the entire European Union since 2018, but has a partial approval in the U.S. and other parts of the world, where it is widely used. [7] [8]
Thiamethoxam was developed by Ciba-Geigy (now Syngenta) in 1991 [9] and launched in 1998; [10] a patent dispute arose with Bayer which already had patents covering other neonicotinoids including imidacloprid and clothianidin. In 2002 the dispute was settled, with Syngenta paying Bayer $120 million in exchange for worldwide rights to thiamethoxam. [11]
Thiamethoxam was first prepared by chemists at Ciba Geigy in 1991. S-Methyl-N-nitro-isothiourea is treated with methylamine to give N-methyl nitroguanidine. This intermediate is used in a Mannich reaction with formaldehyde in formic acid to give 3-methyl-4-nitroimino-1,3,5-oxadiazinane. In the final step, the heterocycle is N-alkylated with a thiazole derivative to give a mixture of E and Z isomers of the final product. [12]
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.[ citation needed ] 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. [13] : 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". [14] : 16
The selective toxicity of neonicotinoids like thiamethoxam for insects versus mammals is due to the higher sensitivity of insects' acetylcholine receptors. [15] 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. [13] : 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. [13] : 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". [13] : 20 Thiamethoxam at sublethal concentrations can increase aggressiveness and cannibalism in commercially harvested shrimp such as Procambarus clarkii [16] In bioassays of aquatic organisms, fish, aquatic primary producers, mollusks, worms, and rotifers are often largely insensitive to thiamethoxam concentrations found in surface waters, but insects, such as chironomid larvae are especially susceptible. [17] [18]
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. [19] Doses of equal or more than 0.5 ng/bee caused longer foraging flights. [19]
Thiamethoxam has been approved for use in the US as an antimicrobial pesticide, wood preservative and as a insecticide; it was first approved in 1999. [20] : 4 & 14 It is still approved for use in a wide range of crops. [21] [22]
On September 5, 2014 Syngenta petitioned the EPA to increase the legal tolerance for thiamethoxam residue in numerous crops. [23] It wanted to use thiamethoxam as a leaf spray, rather than just a seed treatment, to treat late to midseason insect pests. [24]
The estimated annual use of the compound in US agriculture is mapped by the US Geological Service and showed an increasing trend from its introduction in 2001 to 2014 when it reached 1,420,000 pounds (640,000 kg). [25] However, use from 2015 to 2019 dropped sharply following concerns about the effect of neonicotinoid chemicals on pollinating insects. [26] In May 2019, the Environmental Protection Agency revoked approval for a number of products containing thiamethoxam as part of a legal settlement. [27] However, certain formulations continue to be available. [22]
In 2012, several peer reviewed independent studies were published showing that several neonicotinoids had previously undetected routes of exposure affecting bees including through dust, pollen, and nectar; that sub-nanogram toxicity resulted in failure to return to the hive without immediate lethality, the primary symptom of colony collapse disorder; and showing environmental persistence in agricultural irrigation channels and soil. However, not all earlier studies carried out before 2014 have found significant effects. [28] These reports prompted a formal peer review by the European Food Safety Authority, which stated in January 2013 that neonicotinoids pose an unacceptably high risk to bees, and that the industry-sponsored science upon which regulatory agencies' claims of safety have relied on may be flawed and contain several data gaps not previously considered. [29] In April 2013, the European Union voted for a two-year restriction on neonicotinoid insecticides. The ban restricts the use of imidacloprid, clothianidin, and thiamethoxam on crops that attract bees. [30]
In February 2018, the European Food Safety Authority published a new report indicating that neonicotinoids pose a serious danger to both honey bees and wild bees. [31] In April 2018, the member states of the European Union decided to ban the three main neonicotinoids (clothianidin, imidacloprid and thiamethoxam) for all outdoor uses. [32]
Thiamethoxam is approved for a wide range of agricultural, viticultural(vineyard), and horticultural uses. [13] : 17
In January 2021 the UK allowed this pesticide to be used to save sugar beet plants in danger of damage from beet yellows virus which is transmitted by aphids. [33] However, due to lower levels of this disease than was expected, it was announced in March 2021 that the conditions for emergency use had not been met. The UK made similar decisions in 2022, 2023, and 2024 but in these three years the predicted incidence level of yellow virus was met, and in March 2024 it was announced that the use of Crusier SB (a pesticide which contains thiamethoxam) would be allowed for a third consecutive year. [34] [35]
Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others. The most common of these are herbicides, which account for approximately 50% of all pesticide use globally. Most pesticides are used as plant protection products, which in general protect plants from weeds, fungi, or insects. In general, a pesticide is a chemical or biological agent that deters, incapacitates, kills, or otherwise discourages pests. Target pests can include insects, plant pathogens, weeds, molluscs, birds, mammals, fish, nematodes (roundworms), and microbes that destroy property, cause nuisance, or spread disease, or are disease vectors. Along with these benefits, pesticides also have drawbacks, such as potential toxicity to humans and other species.
Insecticides are pesticides used to kill insects, and certain other arthropods such as spiders. They include ovicides and larvicides used against insect eggs and larvae, respectively. Acaricides, which kill mites and ticks, are not strictly insecticides, but are usually classified together with insecticides. The major use of Insecticides is agriculture, but they are also used in home and garden, industrial buildings, vector control and control of insect parasites of animals and humans. Insecticides are distinct from repellents, which repel but do not kill.
Under United States law, pesticide misuse is considered to be the use of a pesticide in a way that violates laws regulating their use or endangers humans or the environment; many of these regulations are laid out in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Pesticide misuse encompasses a range of practices, including overapplication, incorrect timing, and the use of banned substances. This global issue not only threatens environmental safety but also undermines efforts towards sustainability. The risk of pesticide pollution at a global scale necessitates a concerted effort to understand and mitigate misuse. The most common instances of pesticide misuse are applications inconsistent with the labeling, which can include the use of a material in any way not described on the label, changing dosage rates, or violating specific safety instructions. Pesticide labels have been criticized as a poor risk communication vehicle, leading some officials and researchers to question whether "misuse" is an appropriate term for what are often "unintended uses" resulting from a poor understanding of safety and application instructions. Other kinds of pesticide misuse include the sale or use of an unregistered pesticide or one whose registration has been revoked and the sale or use of an adulterated or misbranded pesticide. Under most jurisdictions, it is illegal to alter or remove pesticide labels, to sell restricted pesticides to an uncertified applicator, or to fail to maintain sales and use records of restricted pesticides.
Bifenthrin is a pyrethroid insecticide. It is widely used against ant infestations.
Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid previously sold under the brand name Sevin, which was a trademark of the Bayer Company. The Sevin trademark has since been acquired by GardenTech, which has eliminated carbaryl from most Sevin formulations. Union Carbide discovered carbaryl and introduced it commercially in 1958. Bayer purchased Aventis CropScience in 2002, a company that included Union Carbide pesticide operations. Carbaryl was the third-most-used insecticide in the United States for home gardens, commercial agriculture, and forestry and rangeland protection. As a veterinary drug, it is known as carbaril (INN).
Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system. Specifically, it causes a blockage of the nicotinergic neuronal pathway. By blocking nicotinic acetylcholine receptors, imidacloprid prevents acetylcholine from transmitting impulses between nerves, resulting in the insect's paralysis and eventual death. It is effective on contact and via stomach action. Because imidacloprid binds much more strongly to insect neuron receptors than to mammal neuron receptors, this insecticide is more toxic to insects than to mammals.
Pesticides vary in their effects on bees. Contact pesticides are usually sprayed on plants and can kill bees when they crawl over sprayed surfaces of plants or other areas around it. Systemic pesticides, on the other hand, are usually incorporated into the soil or onto seeds and move up into the stem, leaves, nectar, and pollen of plants.
Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole chemical family. Fipronil disrupts the insect central nervous system by blocking the ligand-gated ion channel of the GABAA receptor and glutamate-gated chloride (GluCl) channels. This causes hyperexcitation of contaminated insects' nerves and muscles. Fipronil's specificity towards insects is believed to be due to its greater binding affinity for the GABAA receptors of insects than to those of mammals, and for its action on GluCl channels, which do not exist in mammals. As of 2017, there does not appear to be significant resistance among fleas to fipronil.
Fenthion is an organothiophosphate insecticide, avicide, and acaricide. Like most other organophosphates, its mode of action is via cholinesterase inhibition. Due to its relatively low toxicity towards humans and mammals, fenthion is listed as moderately toxic compound in U.S. Environmental Protection Agency and World Health Organization toxicity class.
Neonicotinoids are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s.
Nitenpyram is a chemical frequently used as an insecticide in agriculture and veterinary medicine. The compound is an insect neurotoxin belonging to the class of neonicotinoids which works by blocking neural signaling of the central nervous system. It does so by binding irreversibly to the nicotinic acetylcholine receptor (nACHr) causing a stop of the flow of ions in the postsynaptic membrane of neurons leading to paralysis and death. Nitenpyram is highly selective towards the variation of the nACHr which insects possess, and has seen extensive use in targeted, insecticide applications.
Cyhalothrin is an organic compound that, in specific isomeric forms, is used as a pesticide. It is a pyrethroid, a class of synthetic insecticides that mimic the structure and properties of the naturally occurring insecticide pyrethrin which is present in the flowers of Chrysanthemum cinerariifolium. Pyrethroids, such as cyhalothrin, are often preferred as an active ingredient in agricultural insecticides because they are more cost-effective and longer acting than natural pyrethrins. λ-and γ-cyhalothrin are now used to control insects and spider mites in crops including cotton, cereals, potatoes and vegetables.
The environmental effects of pesticides describe the broad series of consequences of using pesticides. The unintended consequences of pesticides is one of the main drivers of the negative impact of modern industrial agriculture on the environment. Pesticides, because they are toxic chemicals meant to kill pest species, can affect non-target species, such as plants, animals and humans. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, because they are sprayed or spread across entire agricultural fields. Other agrochemicals, such as fertilizers, can also have negative effects on the environment.
Clothianidin is an insecticide developed by Takeda Chemical Industries and Bayer AG. Similar to thiamethoxam and imidacloprid, it is a neonicotinoid. Neonicotinoids are a class of insecticides that are chemically similar to nicotine, which has been used as a pesticide since the late 1700s. Clothianidin and other neonicotinoids act on the central nervous system of insects as an agonist of nAChR, the same receptor as acetylcholine, the neurotransmitter that stimulates and activating post-synaptic acetylcholine receptors but not inhibiting AChE. Clothianidin and other neonicotinoids were developed to last longer than nicotine, which is more toxic and which breaks down too quickly in the environment.
Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee colony disappear, leaving behind a queen, plenty of food, and a few nurse bees to care for the remaining immature bees. While such disappearances have occurred sporadically throughout the history of apiculture, and have been known by various names, the syndrome was renamed colony collapse disorder in early 2007 in conjunction with a drastic rise in reports of disappearances of western honey bee colonies in North America. Beekeepers in most European countries had observed a similar phenomenon since 1998, especially in Southern and Western Europe; the Northern Ireland Assembly received reports of a decline greater than 50%. The phenomenon became more global when it affected some Asian and African countries as well. From 1990 to 2021, the United Nation’s FAO calculated that the worldwide number of honeybee colonies increased 47%, reaching 102 million.
Propoxur (Baygon) is a carbamate non-systemic insecticide, produced from catechol, and was introduced in 1959. It has a fast knockdown and long residual effect, and is used against turf, forestry, and household pests and fleas. It is also used in pest control for domestic animals, Anopheles mosquitoes, ants, gypsy moths, and other agricultural pests. It can also be used as a molluscicide.
This is an index of articles relating to pesticides.
Acetamiprid is an organic compound with the chemical formula C10H11ClN4. It is an odorless neonicotinoid insecticide produced under the trade names Assail, and Chipco by Aventis CropSciences. It is systemic and intended to control sucking insects (Thysanoptera, Hemiptera, mainly aphids) on crops such as leafy vegetables, citrus fruits, pome fruits, grapes, cotton, cole crops, and ornamental plants. It is also a key pesticide in commercial cherry farming due to its effectiveness against the larvae of the cherry fruit fly.
Thiacloprid is an insecticide of the neonicotinoid class. Its mechanism of action is similar to other neonicotinoids and involves disruption of the insect's nervous system by stimulating nicotinic acetylcholine receptors. Thiacloprid was developed by Bayer CropScience for use on agricultural crops to control of a variety of sucking and chewing insects, primarily aphids and whiteflies.
Sulfoxaflor, also marketed as Isoclast, is a systemic insecticide that acts as an insect neurotoxin. A pyridine and a trifluoromethyl compound, it is a member of a class of chemicals called sulfoximines, which act on the central nervous system of insects.