Rapid insecticide degradation assay

The first part of the laboratory methodology for study of enhanced degradation Involved use of a rapid degradation assay by which an Idea of the rate of insecticide degradation could be obtained for a large number of soils. The soils for this assay were collected during the fall from Iowa cornfields with known histories of Insecticide use. In some cases the soils collected were specifically from fields in which an insecticide had been used for several years and no longer provided suitable control of soil insect pests. In these cases a separate soil was also collected from an adjacent field or from the field fencerow. 

Results of the rapid degradation assay (Table I) are expressed for each insecticide as cumulative mineralization In history soils (treated with that pesticide at least one previous year) and non-history soils (untreated or treated with other insecticides). 

The second component of the laboratory methodology for study of enhanced degradation involved a more intense investigation of the soil degradation of insecticides identified as suspect from the rapid degradation assay (carbofuran, isofenphos, fonofos) as well as 2 additional insecticides (cloethocarb, chlorpyrifos). The degradation... 

Carbofuran Metabolite Assay. Rapid detection of enhanced degradation of carbofuran in soil can be accomplished in two different manners. The first approach is to measure the actual amount of carbofuran remaining after application and compare this value with what might be expected to remain after a selected time. This concept has been used by FMC in the form of a test ticket that colorimetrically determines the amount of carbofuran based on inhibition of acetylcholinesterase. The diagnostic kit is manufactured by Enzy-Tek of Lenexa, KS (20). A disadvantage of this method is lack of specificity due to the ability of the test reagents to react with other soil insecticides and their metabolites that are also acetylcholinesterase inhibitors. 

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