Evaluation of the constituents of vetiver oil against Anopheles minimus (Diptera: Culicidae), a malaria vector in Thailand

Authors: TISGRATOG, RUNGARUN - Kasetsart University; SUKKANON, CHUTIPONG - Kasetsart University; Chauhan, Kamlesh; CHAREONVIRIYAPHAP, THEERAPHAP - Kasetsart University

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2017
Publication Date: 10/6/2017
Citation: Tisgratog, R., Sukkanon, C., Chauhan, K.R., Chareonviriyaphap, T. 2017. Evaluation of the constituents of vetiver oil against Anopheles minimus (Diptera: Culicidae), a malaria vector in Thailand. Journal of Medical Entomology. 55(1):193-199.

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 results from compact assay system supports previous field studies which show that human contact and disease transmission by mosquitoes are interrupted by public health insecticides and repellents. This information can be used by scientists in the private and public sectors that are interested in developing and testing potential biobased repellents.

Technical Abstract: The development of resistance by mosquitoes to current synthetic compounds has resulted in reduced effectiveness of prevention and control methods worldwide. An alternative non-chemical based control tools are needed to be evaluated particularly plant-derived essential oils. Several components of vetiver oil have been documented as insect repellents. However, in detailed knowledge of those components action against insect remains hidden. In this study, behavioral response of Anopheles minimus to four constituents of vetiver oil (valencene, terpinen-4-ol, isolongifolene, vetiverol) was evaluated by using the high-throughput screening assay system. Vetiverol and isolongifolene exhibited strong contact irritancy action at 5.0% and 1.0% concentration, respectively, while moderate action was found in both valencene and terpinen-4-ol at 5.0%. Only at 1.0 and 5.0% of valencene and 0.5% of isolongifolene showed spatial repellency activity. High toxic action was recorded in all concentration of vetiverol and isolongifolene. Meanwhile valencene exhibited high toxic action only at 5.0%, terpinen-4-ol showed very low toxic action in all concentration. These proved that valencene in vetiver oil is the promising constituents that can be developed as an alternative mosquito control mean in efforts to prevent disease transmission.