Metabolic Fate of Emamectin Benzoate in Soil

This is the authors' abstract. We don't add key points for this paper.

Aerobic and anaerobic incubation of microbially active soil with [ 14 C]MAB 1a resulted in measurable evolution of 14 CO 2 . Chromatographic and mass spectral analyses of extractable residues demonstrated the degradation of [ 14 C]MAB 1a to 8aOH-MAB 1a and 8aoxo-MAB 1a . The highest levels of 8aOH-MAB 1a and 8aoxo-MAB 1a were found at the 60-day incubation interval, comprising about 7 and 3%, respectively, of applied radioactivity. At least eight other residues, more polar than MAB 1a, were also formed at low levels (each <5%). By base extraction, HPLC, and gel chromatography, the unextractable residues were found to be non-avermectin components associated with soil humic substances. The majority (76−85%) of these unextractable residues were found in fulvic acid fraction while relatively minor amounts remained in humins (9−14%) and high molecular weight humic acids (4−11%). Quantitatively, soil microbial counts were not affected by MAB 1a treatment. These results demonstrate that emamectin benzoate is biodegradable in soil and will eventually be mineralized to CO 2 .