Evaluation of the genotoxic potential of two rice herbicides, cyhalofop-butyl and quinclorac, in Drosophila melanogaster.

Cyhalofop-butyl, an aryloxyphenoxypropionate acetyl-CoA carboxylase (ACCase) inhibitor, and quinclorac, a quinolinecarboxylic acid herbicide with auxin-like activity, are commonly used in rice production. This study evaluated the genotoxic potential of the herbicides cyhalofop-butyl and quinclorac in the in vivo Drosophila melanogaster smart assay. Trans-heterozygous larvae obtained from crosses between the multiple wing hairs (mwh) and flare-3 (flr 3) strains were exposed to four concentrations (1, 2, 5, and 10 ppm) of each herbicide. Both herbicides significantly increased clone frequencies compared with the negative control. Cyhalofop-butyl exhibited a concentration-related increase in total spot frequencies, whereas quinclorac consistently elevated clone frequencies across all tested concentrations without a clear dose-dependent pattern. To the best of our knowledge, this is the first report demonstrating the genotoxic potential of cyhalofop-butyl. These findings emphasize the need for careful use of herbicides in rice production and support further investigation of alternative products with lower or no genotoxic potential.