An improved odor bait for monitoring populations of Aedes aegypti-vectors of dengue and chikungunya viruses in Kenya

Abstract

BackgroundEffective surveillance and estimation of the biting fraction of Aedes aegypti is critical for accurate determination of the extent of virus transmission during outbreaks and inter-epidemic periods of dengue and chikungunya fever. Here, we describe the development and use of synthetic human odor baits for improved sampling of adult Ae. aegypti, in two dengue and chikungunya fevers endemic areas in Kenya; Kilifi and Busia counties.MethodsWe collected volatiles from the feet and trunks of two female and two male volunteers aged between 25 and 45 years. We used coupled gas chromatography- electroantennographic detection (GC/EAD) analysis to screen for antennally-active components from the volatiles and coupled GC-mass spectrometry (GC/MS) to identify the EAD-active components. Using randomized replicated designs, we compared the efficacies of Biogents (BG) sentinel traps baited with carbon dioxide plus either single or blends of the identified compounds against the BG sentinel trap baited with carbon dioxide plus the BG commercial lure in trapping Ae. aegypti. The daily mosquito counts in the different traps were subjected to negative binomial regression following the generalized linear models procedures.ResultsA total of ten major EAD-active components identified by GC/MS as mainly aldehydes and carboxylic acids, were consistently isolated from the human feet and trunk volatiles from at least two volunteers. Field assays with synthetic chemicals of the shared EAD-active components identified from the feet and trunk gave varying results. Ae. aegypti were more attracted to carbon dioxide baited BG sentinel traps combined with blends of aldehydes than to similar traps combined with blends of carboxylic acids. When we assessed the efficacy of hexanoic acid detected in odors of the BG commercial lure and volunteers plus carbon dioxide, trap captures of Ae. aegypti doubled over the trap baited with the commercial BG lure. However, dispensing aldehydes and carboxylic acids together in blends, reduced trap captures of Ae. aegypti by ~45%-50%.ConclusionsOur results provide evidence for roles of carboxylic acids and aldehydes in Ae. aegypti host attraction and also show that of the carboxylic acids, hexanoic acid is a more effective lure for the vector than the BG commercial lure.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0866-6) contains supplementary material, which is available to authorized users.

Optimisation and field validation of odour-baited traps for surveillance of Aedes aegypti adults in Paramaribo, Suriname

“…aegypti and Ae. albopictus males using BG-Sentinel traps baited with CO 2 , MB5 blend or BG-Lure [17,23,47,48,53]. These findings are not surprising.…”

“…Similarly, studies from Owino et al [47,48] showed that the BG-Lure is not the most effective bait for Aedes aegypti compared to natural human odours and hexanoic acid. Our results and those from Owino et al [47,48] challenge the current view on capturing Aedes mosquitoes in which the BG-Sentinel trap in combination with the BG-Lure as attractant is considered the gold standard [23][24][25]. A possible reason for the reduced captures using the BG-Lure is that the airflow of the BG-Sentinel is less optimal for the cartridge design of the BG-Lure and odours are thus expelled more efficiently by the BG-Bowl.…”

Controlling mosquitoes with semiochemicals: a review

“…For example, many mosquito species have an inherent preference for a specific host (e.g. a preference [26] Phenol [11,40] CO 2 [11,19,61] Terpineol [96] 2,2,6-Trimethylcyclohexane-1,4-dione a [26] p-Cresol [40] Lactic acid [11]/(S)-lactic acid [9,19] Geraniol [96] 1-(4-Ethylphenyl) ethanone a [26] 3-Methylindole (skatole) [40] (R)-1-Octen-3-ol [69,111] Eugenol [96] CHs b : Me-C 29 , n-heptadecane, n-pentacosane, n-hexacosane c…”

Aedes vector–host olfactory interactions in sylvatic and domestic dengue transmission environments

“…Previous work has found improved mosquito catches to specific host constituents as attractants than blends or crude volatiles [8,25], perhaps reflecting the need for additional research to design improved lures.…”

“…Mosquitoes including Aedes (Stegomyia) rely on olfactory cues to locate vertebrate hosts for a blood meal. Previous work has identified vertebrate host chemicals mainly from humans that attract mosquitoes [7,8]. The attractive cues are of practical and epidemiologic relevance and have been exploited in disease vector control and/or surveillance [9][10][11].…”