Persistence of metaflumizone on cabbage (Brassica oleracea Linne) and soil, and its risk assessment.

Metaflumizone is a novel sodium channel blocker insecticide of semicarbazone class. It provides good to excellent control of most of the economically important lepidopterous pests and certain pests in the orders Coleoptera, Hemiptera, Hymenoptera, Diptera, Isoptera, and Siphonaptera. Although metaflumizone has been marketed globally for several years and got registered in India in the year 2009, specifically for the control of DBM on cabbage, to our knowledge, no food safety aspects of metaflumizone residue on cabbage have ever been reported in the literature in India or elsewhere. The present study was undertaken to evaluate the persistence of metaflumizone on cabbage and soil, vis-a-vis its risk assessment, following two spray applications of metaflumizone 220 SC (Verismo®), each at recommended and double dose of 200 and 400 g a.i. ha(-1) respectively. Initial residue deposits of metaflumizone on cabbage were 0.46 and 0.51 mg kg(-1) at recommended and 0.76 and 0.85 mg kg(-1) at double the recommended dose following the first spray and second spray application. The residues persisted beyond 5 days from both the treatments and dissipated with the half-life ranging from 1.7-2.1 days. Initial deposits of metaflumizone on soil ranged from 0.23-0.37 mg kg(-1) and degraded with a half life ranging from 4.0-4.8 days. No degradation product of metaflumizone was detected in cabbage and soil at any point of time. Soil samples collected from the treated field after 7 days were free from any residue of metaflumizone or its metabolites. A pre-harvest waiting period of 3 days after application was suggested based on calculation of theoretical maximum daily intake.