Tian_2026_Pestic.Biochem.Physiol_216_106829

Nematodes are key species that play a crucial role in maintaining soil ecological functions. This study investigated avermectin and cyclobutrifluram, which exhibit efficient and broad-spectrum nematicidal effects, to evaluate their toxicity on behavior, development, physiology, and biochemistry of model organism Caenorhabditis elegans (C. elegans). The results demonstrated both pesticides significantly reduced head thrashes, body bends, body length and width, causing motor dysfunction, sensory impairments, and developmental retardation. Catalase (CAT), glutathione S-transferase (GST), and acetylcholinesterase (AChE) were enhanced at low avermectin concentrations but inhibited at higher concentrations. The content of malondialdehyde (MDA) increased significantly with elevated exposure. GST activity decreased with increasing concentration of cyclobutrifluram, while CAT activity was enhanced at low concentrations but inhibited at high concentrations. Compared to avermectin, lower concentration of cyclobutrifluram significantly altered the activities of succinate dehydrogenase (SDH), Na(+), K(+)-ATPase, Ca(2+)-ATPase, and Mg(2+)-ATPase. Molecular docking revealed that avermectin primarily altered the structure of the enzyme by binding to the active sites of SOD, CAT, AChE, and GST. Cyclobutrifluram mainly altered the structure of the enzyme by binding to the active sites of SDH, Na(+), K(+)-ATPase, Ca(2+)-ATPase. Both pesticides specifically bound to active sites of related enzymes, disrupting their structure and functions and eventually leading to physiological dysfunction. This study revealed the toxicological mechanisms, providing a theoretical basis for further evaluating their pollution risks and managing their applications.