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

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.