Behaviour of the Soil Residues of the Acaricide-Insecticide, [ $^{14}C$ ]Acrinathrin;I. Behaviour during Crop(Maize) Cultivation

In order to elucidate the fate of the residues of the pyrethroid acaricide-insecticide, acrinathrin in soil, maize plants were grown for one month on the specially-made pots filled with two different types of soils containing fresh and one-month-aged residues of []acrinathrin, respectively. The mineralization of []acrinathrin to during the one-month period of aging and of maize cultivation amounted to and , respectively, of the original activities. At harvest after one-month growing, the shoots and roots contained less than 0.1% and 1% of the originally applied activity, respectively, whereas the activity remaining in soil was in both soils. Three degradation products with m/z 198(3-phenoxybenzaldehyde), m/z 214(3-phenoxybenzoic acid), and m/z 228(methyl 3-phenoxybenzoate) besides an unknown were identified from acetone extracts of both soils without and with maize plants after treatment of []acrinathrin, by autoradiography and GC-MS, and those with m/z 225(3-phenoxybenzaldehyde cyanohydrin) and m/z 198 (3-phenoxybenzaldehyde) from acetone extract of the Soil A treated with 50 ppm acrinathrin and grown with maize plants for 30 days were identified by mass spectrometry. These results suggested that the hydrolytic cleavage of the ester linkage adjacent to the with a cyano group, forming 3-phenoxybenzaldehyde cyanohydrin. The removal of hydrogen cyanide therefrom leads to the formation of 3-phenoxybenzaldehyde as one of the major products. The subsequent oxidation of the aldehyde to 3-phenoxybenzoic acid, followed by decarboxylation would evolve . Solvent extractability of the soils where maize plants were grown for 1 month and/or []acrinathrin was aged for 1 month was less than 31% of the original activity and over 95% of the total activity in soil extracts was distributed in the organic phase. Accordingly, acrinathrin turned out to be degraded rapidly in both soils and be bound to soil constituents as well, not being available to crops.