Methomyl is a

carbamate In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formally o ...

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

introduced in 1966. It is highly toxic to humans, livestock, pets, and wildlife. The EU and UK imposed a pesticide residue limit of 20

µg In the metric system, a microgram or microgramme is a unit of mass equal to one millionth () of a gram. The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and United Kingdom whe ...

/kg for apples and oranges. 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.

Use

Methomyl is a broad-spectrum insecticide that is used to kill insect pests. Methomyl is registered for commercial/professional use under certain conditions on sites including field, vegetable, and orchard crops; turf (

sod Sod, also known as turf, is the upper layer of soil with the grass growing on it that is often harvested into rolls. In Australian and British English, sod is more commonly known as ''turf'', and the word "sod" is limited mainly to agricult ...

farms only);

livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals ...

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 Owner-occupancy or home-ownership is a form of housing tenure in which a person, called the owner-occupier, owner-occupant, or home owner, owns the home in which they live. The home can be a house, such as a single-family detached home, single-fa ...

or non-professional application. However, ''

Heliothis virescens ''Chloridea virescens'', commonly known as the tobacco budworm, is a moth of the family Noctuidae found throughout the eastern and southwestern United States along with parts of Central America and South America. It is a major pest of field cro ...

'' developed a resistance to methomyl within 5 years. Other species like

Helicoverpa assulta ''Helicoverpa assulta'', the oriental tobacco budworm, is a moth of the family Noctuidae. ''H. assulta'' adults are migratory and are found all over the Old World Tropics including Asia, Africa, and Australia. This species has a brown coloured ...

also developed resistance after exposure.

Trade names

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

Toxicity

In acute toxicity testing, methomyl is placed in

EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...

Toxicity Category I (the highest toxicity category out of four) via the

oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid **Oral administration of medicines ** Oral examination (also known as an oral exam or oral ...

route and in eye irritation studies. It is in lower Toxicity Categories for inhalation (Category II), acute

dermal The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided in ...

effects (Category III), and acute skin irritation (Category IV). Methomyl is not likely to be a

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...

(EPA carcinogen Category E).

Ecotoxicity

Methomyl has low persistence in the soil environment, with a reported half-life of approximately 14 days. Because of its high solubility in water, and low affinity for soil binding methomyl may have potential for groundwater contamination. The estimated

aqueous An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be rep ...

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...

for the insecticide is 6 days in surface water and over 25 weeks in

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

Synthesis

First prepare thioester Methomyl Synthesis 1 of 3 V1

Second prepare

oxime In organic chemistry, an oxime is a organic compound belonging to the imines, with the general formula , where R is an organic side-chain and R’ may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted ...

from thioester Methomyl Synthesis 2 of 3 V1

Third prepare product from

methyl isocyanate Methyl isocyanate (MIC) is an organic compound with the molecular formula CH3NCO. Synonyms are isocyanatomethane and methyl carbylamine. Methyl isocyanate is an intermediate chemical in the production of carbamate pesticides (such as carbaryl, c ...

and the finished oxime. Methomyl Synthesis 3 of 3 V1

References

External links

* {{Acetylcholine metabolism and transport modulators Acetylcholinesterase inhibitors Carbamate insecticides Endocrine disruptors Oxime carbamates