Korean Young Entomologists (KYE) On-Demand Presentations
Efficacy of transfluthrin impregnated water hyacinth (Eichhornia crassipes) strips against susceptible Aedes aegypti and Anopheles minimus (Diptera: Culicidae) using WHO tube bioassay
Postdoctoral Research Fellow Kasetsart University Chatuchak, Krung Thep, Thailand
Due to limitations of insecticide-treated nets, new vector control tools against residual malaria transmission need to be invented, developed, evaluated and selected. Spatial repellents (SRs) were marketed for decades, but recently spotlighted to fill the outdoor transmission gaps. In this study, efficacy and persistency of the SRs were determined using high-throughput screening system (HITSS). First, multiple lethal (50%, 75%, and 99%) and a discriminating concentration (DC) of transfluthrin (TFT) post-treated filter papers at seven different air-dried time points from an hour to four weeks of were compared. Second, discriminating concentrations of two highly volatile pyrethroids: transfluthrin (TFT) and metofluthrin (MET) were impregnated to two natural fabrics: Pha Krasop and Water Hyacinth and tested against pyrethroids susceptible Aedes aegypti (USDA) using toxicity (TOX) assay of HITSS. Additionally, all the results were compared with a synthetic fabric from one of commercial SR products in Thailand namely, Hanging Guard® (Earth Thailand Company) as a positive control. Subsequently, persistency of each fabric was compared following WHO’s mosquito net washing protocols (0, 1, 5, 10, 15, 20, and 25 washes). Overall, without washing, all tested fabrics and chemicals achieved 100% mortality at 24h post-exposure. However, MET impregnated natural fabrics decreased efficacy at 10 washes while TFT was consistent up to 20 washes. Interestingly, a synthetic fabric was more stable with MET than TFT.