مشخصات پژوهش

Abstract: Background: Insect vector control is facing the challenges of resistance development and environmental hazards caused by synthetic pesticides. This has led to a considerable market opportunity for botanical insecticides. In this scenario, our study investigated the potential of selected bioactive monoterpenoids, carvacrol and thymol, as safe and eective tools to control the West Nile vector Culex pipiens. Furthermore, the combined eect of thymol-carvacrol mixtures and their possible interactions were assessed. Methods: For determining larvicidal and ovicidal 50% lethal concentration (LC50), each monoterpenoid was tested at dierent concentrations (5–500 mg/L). Then, the fixed ratio method was used for evaluating their combinational ecacy. Results: Carvacrol was more toxic against larvae of Cx. pipiens, with a LC50 value of 14 mg/L, whereas thymol exhibited a LC50 value of 49 mg/L. Comparable trends of ecacy were observed when toxicity on Cx. pipiens eggs was investigated, with LC50 values of 7 and 13 mg/L for carvacrol and thymol, respectively. In combinational toxicity assays, the mixture thymol-carvacrol at 1:4 ratio achieved a synergistic eect against larvae of Cx. pipiens, whereas an additive eect was observed on eggs. Other ratios showed antagonistic eects. Conclusions: Overall, our findings pointed out that the 1:4 ratio of thymol-carvacrol blend can enhance the insecticidal ecacy on Cx. pipiens young instars and can be considered further as active ingredient for developing botanical insecticides to be used in mosquito control operations.