Methomyl

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Methomyl is a carbamate insecticide introduced in 1966. It is highly toxic to humans, livestock, pets, and wildlife.[1] The EU imposed a pesticide residue limit of 0,01 mg/kg for all fruit and vegetables.[2]

Methomyl is a common active ingredient in commercial fly bait, for which the label instructions in the United States warn that "It is a violation of Federal Law to use this product in a manner inconsistent with its labeling." "Off-label" uses and other uses not specifically targeted at problem insects are illegal, dangerous, and ill-advised.[3][4]

Use

Methomyl is a broad-spectrum insecticide that is used to kill insect pests.[5] Methomyl is registered for commercial/professional use under certain conditions on sites including field, vegetable, and orchard crops; turf (sod farms only); livestock quarters; commercial premises; and refuse containers. Products containing 1% Methomyl are available to the general public for retail sale, but more potent formulations are classified as restricted-use pesticides: not registered for homeowner or non-professional application.[5] However, Heliothis virescens developed a resistance to methomyl within 5 years.[6] Other species like Helicoverpa assulta also developed resistance after exposure.[7]

Toxicity

In acute toxicity testing, methomyl is placed in EPA Toxicity Category I (the highest toxicity category out of four) via the oral route and in eye irritation studies.[5] It is in lower Toxicity Categories for inhalation (Category II), acute dermal effects (Category III), and acute skin irritation (Category IV). Methomyl is not likely to be a carcinogen (EPA carcinogen Category E).[5]

Ecotoxicity

Methomyl has low persistence in the soil environment, with a reported half-life of approximately 14 days.[8] Because of its high solubility in water, and low affinity for soil binding methomyl may have potential for groundwater contamination.[5][9] The estimated aqueous half-life for the insecticide is 6 days in surface water and over 25 weeks in groundwater.[9]

Synthesis

First prepare thioester:

File:Methomyl Synthesis 1 of 3 V1.svg

Second prepare oxime from thioester:

File:Methomyl Synthesis 2 of 3 V1.svg

Third prepare product from methyl isocyanate and the finished oxime:

File:Methomyl Synthesis 3 of 3 V1.svg

Trade names

Common names for methomyl include metomil and mesomile. Trade names include Template:Not a typo, Agrinate, DuPont 1179, Flytek, Kipsin, Lannate, Lanox, Memilene, Methavin, Methomex, Nudrin, NuBait, Pillarmate and SD 14999 [9]

References

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  1. Methomyl at Extension Toxicology Network
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  3. Conservation Warden Warns: Fly bait to control wild animals – illegal and a bad idea (Wisconsin Department of Natural Resources)
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External links

Template:Insecticides Template:Acetylcholine metabolism and transport modulators Template:Authority control