Behavioural and antennal responses of Aedes aegypti (l.) (Diptera: Culicidae) gravid females to chemical cues from conspecific larvae.

Antoine Boullis,François Verheggen,Margaux Mulatier,Anubis Vega-Rúa,Lyza Héry,Christelle Delannay

doi:10.1371/journal.pone.0247657

Antoine Boullis, François Verheggen + Show 4 more

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https://doi.org/10.1371/journal.pone.0247657

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Abstract

Mass trapping of gravid females represents one promising strategy for the development of sustainable tools against Aedes aegypti. However, this technique requires the development of effective odorant lures that can compete with natural breeding sites. The presence of conspecific larvae has been shown to stimulate oviposition. Hence, we evaluated the role of four major molecules previously identified from Ae. aegypti larvae (isovaleric, myristoleic, myristic [i.e. tetradecanoic], and pentadecanoic acids) on the oviposition of conspecific females, as well as their olfactory perception to evaluate their range of detection. Using flight cage assays, the preference of gravid females to oviposit in water that previously contained larvae (LHW) or containing the four larval compounds was evaluated. Then, compounds and doses inducing the highest stimulation were challenged for their efficacy against LHW. Only isovaleric acid elicited antennal response, suggesting that the other compounds may act as taste cues. Pentadecanoic acid induced significant oviposition stimulation, especially when dosed at 10 ppm. Myristoleic acid and isovaleric acid deterred oviposition at 10 and 100 ppm, while no effect on oviposition was observed with myristic acid irrespectively of the dose tested. When the four compounds were pooled to mimic larvae's chemical signature, they favored oviposition at 1 ppm but negatively affected egg-laying at higher concentrations. When properly dosed, pentadecanoic acid and the blend of compounds may be promising lures for ovitraps as they could compete with LHW. Due to their low volatility, their effect should be further evaluated under field conditions, in addition with long-range attractants for developing effective tools against gravid females.

Highlights

The yellow fever mosquito, Aedes aegypti (L.), is a serious threat for human health in tropical and subtropical regions due to its significant vectorial capacity for pathogens of medical importance [1, 2]
Larval holding water (LHW–i.e. water that previously contained larvae) stimulated gravid females for oviposition when compared to ultrapure water (UPW) in our experimental set-up, for all tested densities (Table 1)
Positive oviposition activity index (OAI) values were observed for pentadecanoic acid at doses of 1, 10 and 100 ppm, with attraction considered significant at 10 ppm when compared to UPW (OAI = 0.38 ± 0.09, Student’s t-test: t = 4.12, Df = 4, P = 0.014)

Summary

Introduction

The yellow fever mosquito, Aedes aegypti (L.), is a serious threat for human health in tropical and subtropical regions due to its significant vectorial capacity for pathogens of medical importance [1, 2]. As no efficient prophylactic treatments are available against most of Aedesborne diseases, vector control remains the most effective way to prevent and contain. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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