Toxicity of imidacloprid to collembolans in two tropical soils under different soil moisture

Abstract

Shifts in precipitation regimes due to the predicted climate changes can alter the water content in tropical soils and, consequently, may influence the toxicity of pesticides to soil fauna. This study assessed the influence of soil moisture content on the toxicity of the insecticide imidacloprid to the collembolans Folsomia candida in two tropical soils and evaluated the risk of this active ingredient for this species in the soils tested through the toxicity exposure ratio approach. Acute and chronic toxicity tests with F. candida were performed using an Entisol and an Oxisol. The soils were spiked with increasing imidacloprid concentrations while simulating normal water availability (60% of the water holding capacity [WHC]) and water restriction (30 or 45% WHC) for the tests. In the Oxisol, the reduction of soil moisture content significantly increased the toxic effects of imidacloprid on F. candida's survival (LC 50 at 45% WHC = 23.8 vs. LC 50 at 60% WHC >64 mg kg −1) and reproduction (effective concentration causing reductions in species reproduction of 50% [EC 50 ] at 45% WHC = 0.32 vs. EC 50 at 60% WHC = 2.83 mg kg −1), but in the Entisol no clear influence of the soil moisture on the toxicity of imidacloprid for collembolans was found. A significant risk for F. candida was observed in the Oxisol only when in water restriction, whereas in the Entisol it occurred regardless of soil moisture, suggesting that the imidacloprid hazard and risk for F. candida may be increased if soil moisture decreases due to climate changes, depending on the soil type.

Pesticide effects on the abundance of springtails and mites in field mesocosms at an agricultural site

“…Our experimental setup is a robust method for assessing the effects of pesticide exposure on natural soil fauna abundance under field-realistic conditions, as the mesocosm enclosure of the soil core does not change the natural environment beyond the effects of the pesticide being assessed. Temperature and moisture influence the toxicity of imidacloprid in the springtail Folsomia candida (Bandeira et al, 2020 ; Braúlio Hennig et al, 2020 ). Although the soil moisture content did not differ between undisturbed soil and soil in mesocosms, the temperature outside our mesocosms was ~1°C higher during the day and lower during the night inside mesocosms compared to outside.,.…”

The emergence, trajectory, and impacts of emerging contaminants publications in the Journal of Environmental Quality

“…Beyond hormones, PPCPs, and nanoparticles, JEQ papers in the area of emerging contaminants have also begun to include novel pesticides. In 2016-2021, JEQ published four papers on neonicotinoid insecticides, one of which was a laboratorybased bioassay study to understand how changing soil moisture conditions expected in future climate scenarios affect the toxicity of neonicotinoids to nontarget insects (Hennig et al, 2020). Beringer et al (2021) determined partition coefficients (K d and K OC ) for clothianidin in wetland soils to determine how oxidation-reduction conditions and organic carbon content of the soils affected clothianidin sorption.…”

Multiplatform Metabolomics to Understand the Imidacloprid-Induced Toxicity in Drosophila

“…Accordingly, it is essential to evaluate and understand IMD toxicity in order to design potential strategies for its mitigation. A few studies have been conducted to elucidate the impact of IMD on different model species, such as Daphnia (Daphnia magna), zebrafish (Danio rerio), brown shrimp (Farfantepenaeus aztecus), collembolans (Folsomia candida), etc. Still, the exact toxicological mechanism/pathway of the neonicotinoid insecticide IMD on other organisms is unknown.…”