Toxicity and genotoxicity of imidacloprid in the tadpoles of Leptodactylus luctator and Physalaemus cuvieri (Anura: Leptodactylidae)

Abstract

Imidacloprid is a neonicotinoid insecticide used to control agricultural pests around the world. This pesticide can have adverse effects on non-target organisms, especially in aquatic environments. The present study evaluated the toxicity of an imidacloprid-based insecticide in amphibians, using Leptodactylus luctator and Physalaemus cuvieri tadpoles as study models. Spawning of both species were collected within less than 24 h of oviposition from a non-agricultural land at Erechim, Rio Grande do Sul state, Brazil. Survival, swimming activity, body size, morphological malformations, and genotoxic parameters were analyzed at laboratory conditions. A short-term assay was conducted over 168 h (7 days) with five different concentrations of imidacloprid (3–300 µg L−1) being tested. The insecticide did not affect survival, although the tadpoles of both species presented reduced body size, malformed oral and intestine structures, and micronuclei and other erythrocyte nuclear abnormalities following exposure to this imidacloprid-based compound. Exposure also affected swimming activity in L. luctator, which reflected the greater sensitivity of L. luctator to imidacloprid in comparison with P. cuvieri. The swimming activity, body size, and malformations observed in L. luctator and the morphological malformations found in P. cuvieri indicated that even the lowest tested concentration of the insecticide were harmful to amphibians. At concentrations of over 3 μg L−1, P. cuvieri presents a smaller body size, and both species are affected by genotoxic cell damage. This demonstrates that imidacloprid is potentially toxic for the two study species at environmentally relevant concentrations.

The Use of Multiple Biomarkers to Assess the Health of Anuran Amphibians in the Brazilian Cerrado Savanna: An Ecotoxicological Approach

“…The occurrence of DNA damage in amphibians exposed to pesticides has been evaluated in both the larval stage (Samojeden et al, 2022) and the adults (Ascoli-Morrete et al, 2022), given that these vertebrates are considered to be one of the animal groups most sensitive to agricultural contaminants (Van Meter et al, 2015). Boccioni et al (2022) recorded DNA damage in Rhinella arenarum tadpoles exposed to glyphosate (2.5 mg/L) and glufosinate ammonium (2.5 mg/L), both individually and mixed (50:50, % v/v), with DNA damage being recorded in all the treatments with these insecticides.…”

Imidacloprid disrupts larval molting regulation and nutrient energy metabolism, causing developmental delay in honey bee Apis mellifera

“…Available reports mainly focus on the epistatic effects of toxicity, with limited investigation into the involved biochemical mechanisms. Imidacloprid is known to pose a potential health risk to children through dietary exposure ( Anderson and Harmon-Threatt, 2021 ), and may lead to developmental abnormalities in amphibians ( Samojeden et al, 2022 ) and fish ( Islam et al, 2019 ). Furthermore, negative effects on pupal development in insects have been observed ( Jia and Li, 2023 ).…”

Development and application of a mini-QuEChERS method for the determination of pesticide residues in anuran adipose tissues

“…[7][8][9][10] Pesticides can have many adverse effects on amphibians, including decreased growth and developmental rates, increased incidence of external abnormalities, impaired reproductive potential, and, most drastically, death. [11][12][13][14][15][16][17] A part of the anuran lifetime occurs in ponds, rivers, streams, and temporary pools associated with agricultural areas with intense pesticide usage. 15 Some anuran species that inhabit these environments may be exposed to the toxic effects of pesticide residues.…”

“…7–10 Pesticides can have many adverse effects on amphibians, including decreased growth and developmental rates, increased incidence of external abnormalities, impaired reproductive potential, and, most drastically, death. 11–17…”