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Statistical analysis of decay of organophosphorus and pyrethroid insecticides and carbaryl on paddy rice, maize, sunflowers and field peas

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Morton, R and Brayan, JG and Desmarchelier, JM and Dilli, S and Haddad, PR and Sharp, GJ (2001) Statistical analysis of decay of organophosphorus and pyrethroid insecticides and carbaryl on paddy rice, maize, sunflowers and field peas. Journal of Stored Products Research, 37 (3). pp. 277-285. ISSN 0022-474X

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Abstract

A model is developed to describe the decay of seven insecticides on stored paddy rice, maize, sunflowers and peas, and is shown to be more precise than each of six literature models on pesticide decay. It relates residues (R), as a ratio of applied concentration (R0), to time after insecticide application (t), modifying the usual first-order kinetics equation lnR=lnR0−kt by assuming that the rate constant k has a mixture of values according to a gamma distribution with mean K. The resulting equation is lnR=lnR0−Kc ln(1+t/c), where c is a constant determined empirically. For large c, this model reduces to the first-order model with K=k. The parameter K is further modelled as linear in temperature for maize and rice. The rate of loss of protectants was found not to be seriously affected by co-application with other insecticides, and this is a useful finding for future studies on rates of loss of grain protectants. The apparent rate of loss was also not seriously affected by the method of analysis, whether by gas chromatography or high-performance liquid chromatography, and this finding supports previous validation of the methods.

Item Type: Article
Keywords: Pyrethroids; Organophosphorus insecticides; Carbaryl; Residues; Models; Pesticide analysis
Journal or Publication Title: Journal of Stored Products Research
Page Range: pp. 277-285
ISSN: 0022-474X
Identification Number - DOI: 10.1016/S0022-474X(00)00030-8
Additional Information: The definitive version is available at http://www.sciencedirect.com
Date Deposited: 29 Oct 2008 01:54
Last Modified: 18 Nov 2014 03:52
URI: http://eprints.utas.edu.au/id/eprint/7883
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