DETERMINING DISCRIMINATING CONCENTRATIONS OF TRANSFLUTHRIN AND PERMETHRIN USING THE WHO BOTTLE ASSAY AGAINST AEDES ALBOPICTUS IN THAILAND.

The spread of vector-borne diseases by Aedes albopictus necessitates precise monitoring of insecticide resistance to maintain the effectiveness of control strategies. This study aimed to establish discriminating concentrations (DCs) for high-volatility transfluthrin and low-volatility permethrin pyrethroids widely used in vector control programs in Thailand against Ae. albopictus using the World Health Organization (WHO) bottle bioassay guidelines. Non-blood-fed, 3-5-day-old female mosquitoes were exposed to serial concentrations of transfluthrin and permethrin, and knockdown and mortality were recorded at 1 h and 24 h, respectively. A probit analysis was conducted to determine dose-response relationships. The results demonstrated a clear dose-dependent response to transfluthrin and permethrin. The established DCs were 1.712 μg/bottle and 22.74 μg/bottle for transfluthrin and permethrin, respectively. These findings provide essential reference points for monitoring insecticide resistance in Ae. albopictus populations of Thailand and offer critical guidance for optimizing vector control strategies to ensure the efficacy of pyrethroids in disease prevention programs.