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]
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 (sodfarms 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]
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]
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] The estimated aqueous half-life for the insecticide is 6 days in surface water and over 25 weeks in groundwater.
First prepare thioester:
Second prepare oxime from thioester:
Third prepare product from methyl isocyanate and the finished oxime:
Common names for methomyl include metomil and mesomile. Trade names include, Agrinate, DuPont 1179, Flytek, Kipsin, Lannate, Lanox, Memilene, Methavin, Methomex, Nudrin, NuBait, Pillarmate and SD 14999 [9]