Studies on the mechanism of the contact toxicity of carvone against Tribolium castaneum

Carvone exhibits significant insecticidal activity against Tribolium castaneum. Whereas, the precise underlying mechanism of carvone's toxicity remains elusive. In this study, we aimed to investigate the contact toxicity mechanism of carvone on T. castaneum through a comprehensive set of experiments. These experiments included observation of poisoning symptoms in T. castaneum, a time-mortality test, analysis of weight measurement and respiration activities, histological assessment, enzymatic assays, and molecular simulation studies. Physiological analyses show that carvone induces excitement, spasms, and a comatose state in T. castaneum, accompanied by darkening of the body surface. Survival rates significantly dropped by 44% after 8–12 h of carvone treatment. Carvone also affects metabolism, increasing CO2 release and body weight loss. Histopathological examination reveals changes in the body wall structure, including wax particle shape alterations, increased gaps, and damaged hair bases. Abdominal tissue examination shows impacts on muscle and fat tissues, leading to dehydration and impaired physiological functions. Key enzymatic assays demonstrate sustained inhibition of acetylcholinesterase and succinate dehydrogenase activity by carvone, with peak inhibition rates reaching 65.15% and 39.90%, respectively. Carvone exhibits a biphasic effect on ATPases and activates glutathione S-transferase while inhibiting carboxylesterase activity. Molecular docking analysis reveals direct interactions between carvone and acetylcholinesterase in T. castaneum, suggesting its inhibition mechanism. This study provides insights into the insecticidal mechanism of carvone on T. castaneum and contributes to the development of plant-based insecticides.