Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2019
Publication Date: 10/5/2019
Citation: Bibbs, C.S., Kline, J., Kline, D.L., Estaver, J., Strohschein, R., Allan, S.A., Kaufman, P.E., Xue, R., Batich, C.D. 2019. Olfactometric comparison of the volatile insecticide, metofluthrin, through behavioral responses of Aedes albopictus (Diptera: Culicidae). Journal of Medical Entomology. https://doi.org/10.1093/jme/tjz160.
DOI: https://doi.org/10.1093/jme/tjz160

Interpretive Summary: Spatial repellents provide a powerful approach for management of mosquito species through their various forms of irritation and repellency. Conventional approaches to evaluate spatial repellents include field and semi-field evaluations which are hard to interpret. Laboratory evaluations are limited due to the problems of contamination with plastics and other materials, thus confounding results. In this study, ARS scientists from CMAVE, Gainesville, Fl, collaborated in the development of a novel olfactometer that allows effective testing and decontamination between uses. This device was used to evaluate formulated metafluthrin as an effective potential tool for mosquito management.

Technical Abstract: Testing behavioral response to insecticidal volatiles requires modifications to the existing designs of olfactometers. To create a testing apparatus in which there is no chemical memory to confound tests, we detail the technical aspects of a new tool with design influences from other olfactometry tools. Additionally, this new tool was used to evaluate a novel formulation of metofluthrin for use as an outdoor residual treatment. After sourcing materials to prioritize glass and metal construction, a modular wind tunnel (MWT) was developed that hybridizes wind tunnel and olfactometer specifications. Volatile contaminants were removed by strong ultra-violet light within the chamber before and between trials. Repellent trials were conducted with an experimental formulation of metofluthrin and a commercial formulation of esfenvalerate, prallethrin, and piperonyl butoxide (Onslaught Fast Cap) against Aedes albopictus. Toxicant vapors were delivered with attractants from a lure with behavioral responses scored 20min after exposure. Overwhelmingly, upwind attraction to the attractant lure (negative control) and the Onslaught Fast Cap plus lure 90% and 75%, respectively. In contrast, metofluthrin vapors resulted in less than 10% attraction and a concert of repellency, disorientation, and knockdown effects, each followed by a lesser degree of mortality. Our findings demonstrated that a novel modular wind tunnel was functional for mitigating toxic secondary exposures of spatial repellents amidst complex behavioral analysis in mosquitoes. The resulting observations with formulated metofluthrin positively reinforce the merit of transitioning metofluthrin into expanded roles in mosquito management.