Pyrethroids

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Pyrethroids

 

synthetic esters of chrysanthemumic acid; analogs of pyrethrins.

Pyrethroids are obtained either by the reaction of chrysanthemumyl chloride with an alcoholic moiety in the presence of a tertiary amine or by transesterification of the ethyl ester of chrysanthemumic acid in the presence of sodium. The pyrethroids that are most toxic to insects are esters of cyclopentenolones, of substituted benzyl alcohols, and of N-hydroxymethylimides.

Pyrethroids produced today include allethrin (2-allyl-3-meth-yl-2-cyclopenten-4-oI-l-onyl chrysanthemumate), furethrin (2-furfury 1 -3-methyl -2- cyclopenten - 4 -ol -1 - ony 1 chrysanthemum-ate), cyclethrin (2-cyclopentenyl-3-methyl-2-cyclopenten-4-ol-1 -onyl chrysanthemumate), barthrin (6-chloropiperonyl chrysanthemumate), dimethrin (2,4-dimethylbenzyl chrysanthemumate), and tetrametrine [N-(3,4,5,6-tetrahydrophthalimido)-methyl chrysanthemumate]. These compounds, usually in the form of aerosols, are used against household insects.

REFERENCES

Mel’nikov, N. N., and K. D. Shvetsova-Shilovskaia. “Sintez insektitsidov piretrinovogo riada.” Khimicheskaia promyshlennost’, 1955, no. 3, pp. 50–61.
Volkov, Iu. P., and N. F. Shugal. “Sinteticheskie analogi piretrinov. Khimicheskaia promyshlennost’, 1969, no. 9, pp. 14–19.
Chemie der Pflanzenschutz- und Schädlingsbekä mpfungsmittel, vol. 1. Edited by R. Wegler. Berlin, 1970. Pages 87–102.

K. D. SHVETSOVA-SHILOVSKAIA

References in periodicals archive ?
Farmers are being asked to send at least 250 beetles to assess both pyrethroid resistance and parasitaztion rate, though in areas where beetle populations are known to be low, samples of 50 can be sent in for pyrethroid testing only.
Professor Steve Lindsay, from the Department of Biosciences at Durham University in the UK, said: "This study is important because malaria control in sub-Saharan Africa has stalled, partly because the mosquitoes are adapting and becoming resistant to the pyrethroid insecticides used for treating the old bed nets.
This innovation allows sample analysis to be completed in less than two hours--and it can detect pyrethroids at a concentration level as low as 0.02 nanogram per gram of vegetables.
The current study was conducted in the context of the Venda Health Examination of Mothers, Babies, and their Environment (VHEMBE), a prospective birth cohort study investigating the effects of environmental exposures on the health and development of children born in the Vhembe district of Limpopo Province, South Africa, where IRS insecticides, primarily DDT and the pyrethroid deltamethrin, are applied during the malarial season.
The stock solutions of 100 [micro]g m[L.sup.-1] were prepared with pyrethroid standards containing bifenthrin, fenpropathrin, permethrin, cyfluthrin, cypermethrin, fenvalerate, and deltamethrin in n-hexane and stored at -20[degrees]C.
Another 4 randomly selected huts were sprayed with 30 mg/[m.sup.2] of the pyrethroid lambda-cyhalothrin, which was also in a capsule suspension formulation (Icon 10CS).
Runoff of pyrethroids, widely used household insecticides, has led to contamination of urban waterways as well as a need to accurately assess pyrethroid concentrations in waterways.
(60) assessed the use of pyrethroids, Deltamethrin and Permethrin in LLINs, despite resistance being an important factor in reducing their effectiveness and showed that they are likely to be cost effective against malaria even in areas with strong pyrethroid resistance (31).
Other pyrethroid and organophosphates have also been trialled.