AVERMECTIN-B1A METABOLISM IN CELERY - A RESIDUE STUDY

Radioactivity equivalent to less than 4% of the total avermectin B1a applied to mature and immature celery as a mixture of unlabeled and [14C]- or [3H]avermectin B1a remained in harvested plants. The half-lives of radiolabeled avermectin B1a residues as measured by the dissipation of total 3H radioactivity from celery parts ranged from 5.2 to 12.9 days in celery treated at 0.01 and 0.10 lb of Al/acre. The percentage of total radioactivity in celery parts readily extractable with acetone (range of 57.8–97.1%) generally decreased with increasing postharvest intervals. High-performance liquid chromatography of acetone extracts of celery leaves and stalks produced four discernible peaks of radioactivity, designated as polar metabolites, moderately polar metabolites, avermectin B1a, and the Δ8,9 isomer of avermectin B1a. The percentage of acetone extract radioactivity represented by polar metabolites generally increased with increasing postharvest intervals. © 1990, American Chemical Society. All rights reserved.