clothianidin and acetochlor

In natural ecosystems, organisms are commonly exposed to chemical mixtures rather than individual compounds. However, environmental risk is traditionally assessed based on data of individual compounds. In the present study, we aimed to investigate the individual and combined effects of four pesticides [fenobucarb (FEN), chlorpyrifos (CPF), clothianidin (CLO), acetochlor (ACE)] and one heavy metal chromium [Cr(Ⅵ)] on the earthworm (Eisenia fetida) using avoidance behavior as an endpoint. Our results indicated that CLO had the highest toxicity to E. fetida, followed by Cr(Ⅵ), while FEN showed the least toxicity. Two mixtures of CPF+CLO and Cr(Ⅵ)+CPF+CLO+ACE exhibited synergistic effects on the earthworms. The other two quaternary mixtures of CLO+FEN+ACE+Cr(Ⅵ) and Cr(Ⅵ)+FEN+CPF+ACE at low concentrations also displayed synergistic effects on the earthworms. In contrast, the mixture of Cr(Ⅵ)+FEN had the strongest antagonistic effects on E. fetida. Besides, the quinquenary mixture of Cr(Ⅵ)+FEN+CPF+CLO+ACE also exerted antagonistic effects. These findings highlighted the importance to evaluate chemical mixtures. Moreover, our data strongly pointed out that the avoidance tests could be used to assess the effects of combined effects.

Topics: Animals; Avoidance Learning; Carbamates; Chlorpyrifos; Chromium; Drug Synergism; Guanidines; Metals, Heavy; Neonicotinoids; Oligochaeta; Pesticides; Soil Pollutants; Thiazoles; Toluidines

As commonly used pesticides, chlorpyrifos (CPF), fenobucarb (FEN), clothianidin (CLO) and acetochlor (ACE) are widely applied on crops worldwide. In this study, the combined toxicities of their binary, ternary and quaternary mixtures were evaluated using the earthworm Eisenia fetida as test organism. Mixture toxicities were studied using the combination index (CI) method and visualized by isobolograms, and then data were compared with traditional concentration addition (CA) and independent action (IA) models. Two binary mixtures of CPF+FEN and FEN+ACE, two ternary mixtures of CPF+CLO+FEN and CPF+FEN+ACE, and quaternary mixture of CPF+FEN+ACE+CLO exhibited a clear synergistic effect. The CI method was compared with the classical models of CA and IA, indicating that the CI method could accurately predict the combined toxicities of the chemicals. The results indicated that it was difficult to predict combined effects of these pesticides from mode of action alone because of existence of complicated synergistic and antagonistic responses. More attention should be paid to the potential synergistic effects of chemicals interactions, which might cause serious ecological problems.

Topics: Animals; Carbamates; China; Chlorpyrifos; Drug Synergism; Environmental Monitoring; Guanidines; Models, Theoretical; Neonicotinoids; Oligochaeta; Pesticides; Soil Pollutants; Thiazoles; Toluidines