The main component of the scent of Senecio madagascariensis flowers is an attractant for Aedes aegypti (L.) (Diptera: Culicidae) mosquitoes.

Aedes aegypti (L.) (Diptera: Culicidae) is one of the main vectors of arboviruses, including dengue, Zika, and chikungunya. It almost exclusively inhabits urban areas. Both sexes feed on plant carbohydrates, although for males, this is their only food source. In the case of floral nectars, mosquitoes locate plant sugar sources assisted by volatile compounds. In this work, we found that the floral scent of Senecio madagascariensis elicited a behavioral response in males; therefore, we focused on identifying the volatiles emitted by these flowers. The terpenes (±)-α-pinene, ß-pinene, sabinene, and phellandrene and 1-alkenes 1-undecene, and 1-nonene were identified. To determine which compounds are bioactive, pure synthetic lures were assessed using an olfactometer. Only the main compound 1-nonene was an attractant for males. Since our goal was the introduction of synthetic floral-based attractants in toxic sugar-baited traps, we formulated 1-nonene in solid paraffin and stearin matrices to obtain a controlled release system. The bioassay with a toxicological end point showed that the incorporation of a feeding attractant to the toxic sugar trap increased overall mortality. These results suggest that it is possible to use plant volatile compounds or flower cuttings as male Ae. aegypti attractants to improve the efficacy of baited traps.

Quantitative Evaluation of the Behavioral Response to Attractant and Repellent Compounds in Anopheles pseudopunctipennis and Aedes aegypti (Diptera: Culicidae) Larvae.

The mosquito Anopheles pseudopunctipennis (Theobald) is the principal vector for malaria in Latin-America. Aedes aegypti (L.) (Diptera: Culicidae) is the key vector of four important arboviral diseases: dengue, yellow fever, Zika, and chikungunya. Controlling larval stages to reduce the production of new adult mosquitoes is part of the integrated vector management strategies. However, there are few studies about the olfactory behavior on immature stages of mosquitoes, especially in An. pseudopunctipennis. In this work, we have evaluated the behavior of An. pseudopunctipennis and Ae. aegypti larvae in response to attractant or repellent stimuli through a video-tracking analysis. We used the software EthoVision to obtain behavioral variables related to the swimming activity, such as distance, speed, and mobility status. The response to the repellents stimulus results in an increase of the swimming activity and the absolute angular velocity in both species. Otherwise, the responses to the possible attractants stimulus results in a decrease of the activity of the larvae only for Ae. aegypti. The effects of these compounds were weaker in Anopheles; probably as a consequence of their adaptations to different aquatic ecosystems. The study of the larval olfactory response could contribute to the development of new control tools based on 'push-pull' strategies by 'pushing' mosquitoes away from certain places using repellents, and 'pulling' them towards other places like traps baited with attractive cues.