Submitted to: Journal of Medical Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/23/2010
Publication Date: 9/1/2010
Citation: Thanispong, K., Achee, N., Grieco, J., Chauhan, K.R., Bangs, M.J., Suwonkerd, W., Prabaripai, A., Tanasinchayakul, S., Chareonviriyaphap, T. 2010. A high throughput screening system for determining the three actions of insecticides against Aedes aegypti (Diptera: Culicidae) populations in Thailand. Journal of Medical Entomology. 47(5):833-841. Interpretive Summary: Evaluation of potential repellent compounds against mosquito vectors of diseases is time consuming and often involves animal or human subjects. We have developed a laboratory modular assay system that can screen candidate compounds without involving human subjects or animals. This assay system is compact in size and only requires small amounts of the test compound. These findings support previous laboratory and field studies showing man-vector contact and disease transmission are routinely interrupted by repellent action through air (spatial) and contact irritant actions of common public health insecticides. Although significantly different in actions, irritancy and repellency may reflect and be influenced by the background insecticide efficacy status on a particular mosquito population. Public health scientists and regulatory agencies can use this information for decision-making and vector control strategies.
Technical Abstract: Chemicals can protect humans from the bites 30 of hemophagous arthropods through three different primary actions; irritancy (excitation), repellency, or toxicity; actions that can be evaluated using a laboratory-based assay system. In this study, the deterrent and toxic actions of three synthetic pyrethroids and DDT were characterized on six field strains of Aedes aegypti from Thailand under laboratory-controlled conditions using the High Throughput Screening System (HITSS). All six strains showed significant contact irritant responses to the three synthetic pyrethroids but significantly weaker irritant responses to DDT. Marked repellency responses were seen in all six Ae. aegypti test strains exposed to DDT while the synthetic pyrethroids resulted in greater toxicity than DDT under similar test conditions. Although significantly different in actions, irritancy and repellency may reflect and be influenced by the background insecticide susceptibility status of a particular mosquito population. Results from this study can be used to guide decision-making regarding more effective Ae. aegypti adult control in Thailand.