Tebufenpyrad is an

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 t ...

and

acaricide Acaricides are pesticides that kill members of the arachnid subclass ''Acari'', which includes ticks and mites. Acaricides are used both in medicine and agriculture, although the desired selective toxicity differs between the two fields. Termino ...

widely used in

greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These ...

s. It is a white solid chemical with a slight aromatic smell. It is soluble in water and also in organic solvents.http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+7271

Mode of action

Tebufenpyrad is a strong mitochondrial complex I inhibitor. Like

Rotenone Rotenone is an odorless, colorless, crystalline isoflavone used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the seeds and stems of several plants, such as the jicama vine plant, and the roots of several mem ...

, it inhibits electron transport chain by inhibiting the complex I enzymes of mitochondria which ultimately leads to lack of ATP production and finally cell death.

Use

Tebufenpyrad is used mainly in greenhouses around the world. It has been registered under various trade names (i.e.Masai, Pyranica) in countries like

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

and certain

South American South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

countries. It is registered in USA for use on ornamental plants in commercial green houses. The data available presented enough evidence to support unconditional registration of tebufenpyrad for use on ornamental plants in greenhouses.

Exposure and toxicity

It is mainly used in greenhouses and the major form of exposure is through occupational exposure where this chemical is manufactured or used extensively. The possible routes of exposure are through inhalation or dermal exposure. Since it is used in ornamental plants the exposure through food is limited. The LD 50 values for various laboratory animals are as follows:

LD50 In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is the ...

Rat (male) oral 595 mg/kg LD50 Rat (female) oral 997 mg/kg LD50 Mouse (male) oral 224 mg/kg LD50 Mouse (female) oral 210 mg/kg LD50 Rat dermal >2000 mg/kgMacBean C, ed. Tebufenpyrad (119168-77-3). In: The e-Pesticide Manual, 15th Edition, Version 5.0.1 (2011–2012). Surrey UK, British Crop Protection Council

Biotransformation

Hydroxylation In chemistry, hydroxylation can refer to: *(i) most commonly, hydroxylation describes a chemical process that introduces a hydroxyl group () into an organic compound. *(ii) the ''degree of hydroxylation'' refers to the number of OH groups in a ...

is the major and primary

biotransformation Biotransformation is the biochemical modification of one chemical compound or a mixture of chemical compounds. Biotransformations can be conducted with whole cells, their lysates, or purified enzymes. Increasingly, biotransformations are effected w ...

of tebufenpyrad reported both ''in vivo'' and ''in vitro''. Ethyl and tetra-butyl groups are the targets of hydroxylation. The alcohol groups are oxidized to carboxylic groups which can then be conjugated with other groups ''in vivo''. In rodent studies it was shown that 80% of the

pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and ...

was absorbed mainly in the digestive system within 24 hours, the major metabolites being the hydroxylated forms. Most of the compound and its metabolites were excreted through feces and urine. There was no evidence of accumulation in the body of the rodents. The metabolites excreted out differed from male to female in rodents. While males excreted the carboxylic derivatives of the parent compound, the female rats excreted the sulfate conjugates of carboxylic acid. The

values of male and female rats was very different. While the LD50 value of female rats was 997 mg/kg the LD50 for male rats was only 595 mg/kg. This vast difference in LD 50 value might be attributed to this

Consequences of exposure

Tebufenpyrad exposure has been linked to cancer but to date no human data has been conclusive enough to link the two.USEPA Office of Pesticide Programs, Health Effects Division, Science Information Management Branch: "Chemicals Evaluated for Carcinogenic Potential" (April 2006) Recently this pesticide has been shown to affect the dopaminergic neuronal cell lines N27 by disrupting the mitochondrial dynamics. Loss of dopaminergic cells have been linked to

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms beco ...

in which the neuronal mitochondria are affected. These findings may show that tebufenpyrad might also be able to affect the neurons. Overexposure of the pesticide has also led to the development of resistance among different target organisms. Recent studies have detected tebufenpyrad resistance in two

spider mite Spider mites are members of the Tetranychidae family, which includes about 1,200 species. They are part of the subclass Acari (mites). Spider mites generally live on the undersides of leaves of plants, where they may spin protective silk webs, a ...

species in apple trees in Western Australia.

References

{{Reflist Insecticides Acaricides Pyrazoles Tert-butyl compounds