Abstract
Neonicotinoids are potent agonists of nicotine acetylcholine receptors and exert insecticidal effects by causing abnormal excitation of the nervous system. Recently, their effects on mammals, including humans, have become of concern. In the present study, we evaluated the effects of chronic exposure to two neonicotinoids, imidacloprid (IMI) and dinotefuran (DINO), using Caenorhabditis elegans as the model organism. We used 1, 10, 100, and 1000 µM solutions of nicotine, IMI, and DINO dissolved in 1% DMSO. Bioassays (growth, maturation, and reproduction tests) were performed on the L1-L2 larvae of wild-type C. elegans. To evaluate the effect of exposure over multiple generations and the correlation between concentrations and generations, the same study was conducted in second and third generations of the exposed group. The bioassay results showed concentration-dependent adverse effects at concentrations above 10 μM for both IMI and DINO in both tests for one generation. In the multi-generation study, the effect intensified with the progression of generations, and the toxicity of both IMI and DINO was cumulative. This effect was more pronounced in the breeding study, with significant adverse effects comparable to those of nicotine between generations at concentrations ≥1 μM. This study showed that neonicotinoid concentrations within crop residue limits can adversely affect ecosystem organisms. We suggest that chronic exposure to neonicotinoids may have adverse effects across generations, particularly on reproductive performance. These findings suggest the need to conduct a comprehensive toxicity assessment, including genetic analysis, such as RNA sequencing and real-time PCR, in the future
