Sensitivity of Eisenia andrei (Annelida, Oligochaeta) to a commercial formulation of abamectin in avoidance tests with artificial substrate and natural soil under tropical conditions.
Obtaining ecotoxicological data on pesticides in tropical regions is imperative for performing more realistic risk analysis, and avoidance tests have been proposed as a useful, fast and cost-effective tool. Therefore, the present study aimed to evaluate the avoidance behavior of Eisenia andrei to a formulated product, Vertimec® 18 EC (a.i abamectin), in tests performed on a reference tropical artificial soil (TAS), to derive ecotoxicological data on tropical conditions, and a natural soil (NS), simulating crop field conditions. In TAS tests an adaptation of the substrate recommended by OECD and ISO protocols was used, with residues of coconut fiber as a source of organic matter. Concentrations of the pesticide on TAS test ranged from 0 to 7 mg abamectin/kg (dry weight-d.w.). In NS tests, earthworms were exposed to samples of soils sprayed in situ with: 0.9 L of Vertimec® 18 EC/ha (RD); twice as much this dosage (2RD); and distilled water (Control), respectively, and to 2RD: control dilutions (12.5, 25, 50, 75%). All tests were performed under 25 ± 2°C, to simulate tropical conditions, and a 12hL:12hD photoperiod. The organisms avoided contaminated TAS for an EC(50,48h) = 3.918 mg/kg soil d.w., LOEC = 1.75 mg/kg soil d.w. and NOEC = 0.85 mg/kg soil d.w. No significant avoidance response occurred for any NS test. Abamectin concentrations in NS were rather lower than EC(50, 48h) and LOEC determined in TAS tests. The results obtained contribute to overcome a lack of ecotoxicological data on pesticides under tropical conditions, but more tests with different soil invertebrates are needed to improve pesticides risk analysis.
Núcleo de Estudos em Ecossistemas Aquáticos, Departamento de Hidráulica e Saneamento, Escola de Engenharia de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil. metnunes@terra.com.br
Maria Edna Tenório
ME
Nunes
Evaldo Luiz Gaeta
EL
Espíndola
D000818:Animals; D055598:Chemical Phenomena; D054750:Ecotoxicology; D004784:Environmental Monitoring / Q000379:methods*; D007306:Insecticides / Q000633:toxicity*; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000032:analysis / Q000633:toxicity; D009835:Oligochaeta / Q000187:drug effects* / Q000502:physiology; D018570:Risk Assessment; D012989:Soil Pollutants / Q000032:analysis*
D007306:Insecticides; D012989:Soil Pollutants; C048324:abamectin; D007559:Ivermectin