Multidimensional behavioral signatures of Culex quinquefasciatus (Diptera: Culicidae) in response to botanical volatiles reveal divergent patterns of mosquito displacement and behavioral disturbance

Abstract Underground storm drain systems (USDS) are productive but under-targeted habitats for Culex quinquefasciatus, where high organic loads, insecticide resistance, and odor-rich conditions complicate mosquito control. Spatial repellents offer a promising alternative, yet “repellency” encompasses multiple behavioral modes that remain poorly resolved for botanical volatiles. Here, we evaluated 4 individual plant-derived compounds, 2 whole essential oils, selected vapor-phase mixtures, and USDS water odors using a modified excito-repellency chamber to quantify escape, flying, and walking behaviors in Cx. quinquefasciatus. Botanical oils produced distinct, time-dependent behavioral profiles. Eugenol, citronellol, and geraniol primarily elicited escape-dominant responses consistent with spatial repellency, whereas flight activity under peppermint oil varied with active tube exposure level and time, and was accompanied by comparatively weaker escape responses. Mixture responses generally resembled the behavioral profile of the more strongly represented component rather than showing a clearly intermediate pattern. Joint escape–flight trajectories showed that treatments also differed in the temporal organization of these responses, ranging from rapid, sustained displacement to early within-chamber activation followed by delayed escape. Sewer water odors attenuated the magnitude of escape and flight responses but preserved the relative ordering of treatment-specific behavioral profiles. These findings demonstrate that botanical volatiles can produce distinct behavioral response profiles that remain detectable in a chemically complex odor environment. By repeatedly quantifying escape, flight, and walking activity within a single experimental system, this study provides a comparative behavioral framework to identify volatile treatments that warrant further evaluation to alter adult mosquito retention in odor-rich urban infrastructures, such as underground storm drains.