IN VIVO GENOTOXICITY ASSESSMENT OF DIFLUBENZURON AND SPINOSAD IN DROSOPHILA MELANOGASTER WITH THE COMET ASSAY USING HAEMOCYTES AND THE SMART ASSAY

摘要

Diflubenzuron is a benzoylphenylurea derivative that inhibits the synthesis of chitin, and spinosad is an insecticide derived from a naturally occurring bacterium via fermentation. The in vivo genotoxic activity of diflubenzuron and spinosad was studied in Drosophila melanogaster by using two different test systems, namely the Drosophila somatic mutation and recombination test (SMART) and the alkaline comet assay. The alkaline comet assay was conducted using haemocytes of D. melanogaster larvae. The results from the SMART assay showed that neither diflubenzuron nor spinosad were able to induce significant increases in the frequency of the four categories of mutant spots (e.g. small single, large single, twin and total spots). Although diflubenzuron did not induce genotoxic effects in any tested concentrations in the comet assay, spinosad was effective in this assay with haemocytes, inducing significant increases of DNA damage with a direct dose-response relationship. These results confirm the usefulness of the comet assay with haemocytes as an in vivo model and support the possibility that there is a genotoxic risk associated with spinosad exposure. In addition, this is the first study reporting genotoxicity data in somatic cells of Drosophila for diflubenzuron and spinosad.