Earthworm ecotoxicological assessments of pesticides used to treat seeds under tropical conditions

Abstract

Ecotoxicological laboratory tests (lower-tier tests) are fundamental tools for assessing the toxicity of pesticides to soil organisms. In this study, using these tests under tropical conditions, we quantified the impact of the insecticides imidacloprid, fipronil, and thiametoxam, and the fungicides captan and carboxin+thiram, all of which are used in the chemical treatment of crop seeds, on the survival, reproduction, and behavior of Eisenia andrei (Oligochaeta). With the exception of imidacloprid, none of the pesticides tested caused mortality in E. andrei in artificial soils. The LC(50) of imidacloprid was estimated as 25.53 mg active ingredient kg(-1) of dry soil. Earthworm reproduction rates were reduced by imidacloprid (EC(50)=4.07 mgkg(-1)), fipronil (EC(20)=23.16 mgkg(-1)), carboxin+thiram (EC(50)=56.38 mgkg(-1)), captan (EC(50)=334.84 mgkg(-1)), and thiametoxam (EC(50)=791.99 mgkg(-1)). Avoidance behavior was observed in the presence of imidacloprid (AC(50)=0.11 mgkg(-1)), captan (AC(50)=33.54 mgkg(-1)), carboxin+thiram (AC(50)=60.32 mgkg(-1)), and thiametoxam (AC(50)=>20 mgkg(-1)). Earthworms showed a preference for soils with the insecticide fipronil. Imidacloprid was the most toxic of the substances tested for E. andrei. The avoidance test was the most sensitive test for most pesticides studied, but results varied between pesticides. These results offer new insights on the toxicity of pesticides used to treat seeds in tropical regions. However, they should be complemented with higher-tier tests in order to reduce the uncertainties in risk assessment.

Laboratory studies on the effects of a neonicotinoid-containing seed treatment product on non-target soil animals

“…These concentrations are well above that are used and potentially present in the soil under realistic circumstances. PEC of the thiamethoxam-containing Cruiser F350 is 0.201 mg/kg based on literature data (Alves et al 2013). Field concentrations used in practice most probably do not have a negative side effect on springtails, but discharge of this agent into the soil in high concentrations (for example, in the case of an accident or inadequate application) poses a risk to this group of soil animals.…”

ET&C Best Paper of 2016

“…Engineered nanomaterials have also been shown to interfere with assays that are commonly used for HTS platforms [74,87]. This can be through ENMs having luminescent and fluorescent properties or through direct interference with the assay components [74,88,89].…”

“…Taking advantage of this effect has led to a multibillion-dollar industry, which has been described as the second industrial revolution [73]. These unique properties, however, complicate the identification of potential hazard effects as physicochemical properties that can significantly influence toxicity profiles [73,74]. Nanoscale properties have made it very difficult to develop conclusions about hazard identification and hinder the development of effective riskmanagement strategies of ENMs [25].…”

ECOTOXICOLOGICAL BIOASSAYS OF THE EARTHWORMS <i>ALLOLOBOPHORA CALIGINOSA</i> SAVIGNY AND <i>PHERETIMA HAWAYANA</i> ROSA TREATED WITH ARSENATE

“…Chronic toxicity effects of arsenate on earthworm reproduction and growth were assessed according to Alves et al (2013). The bioassays were installed as in the acute toxicity tests which differed only in duration, concentrations and assessment methods.…”

“…Avoidance tests were carried out following the recommendations of Alves et al (2013). For both A. caliginosa and P. hawayana, the arsenate was tested at concentrations 10, 20, 30, 40 and 50 mg kg −1 soil d. w. with 3 replicates for each concentration.…”