AIM: This study evaluated the effect of the insecticide carbofuran and the herbicide metsulfuron-methyl on the abundance and diversity of benthic macroinvertebrates in a paddy ricefield. METHODS: To achieve this goal, two pesticide treatments [the insecticide carbofuran (IC) and the herbicide metsulfuron-methyl (HM)] and a control (Co) treatment with no added pesticide were established in an experimental area of the Plant Science Department of the Federal University of Santa Maria. Soil samples were collected in triplicate from each treatment 30 days before and 1, 10, and 51 days after the pesticide application, for macrofauna identification. RESULTS: Among the 21 taxa identified, Trichoceridae was present only in Co, Hydroptilidae was recorded only in IC, and Corixidae in HM. In Co, the most abundant group was Annelida, while in IC and HM Diptera (Chironomidae) was dominant. Significant differences were observed between Co and IC, in the density of Odontoceridae (Control>IC) and Hydrophilidae (Control<IC), and between Co and HM in the density of Odontoceridae (Control>HM) and Hirudinea (Control<HM). CONCLUSION: In spite of the possible negative effects of the pesticides on the benthic community, the assemblages recovered rapidly.
environmental impact; density; benthic community; biomonitoring; pesticides
