Abstract
BackgroundThe mosquitoes Aedes aegypti and Aedes albopictus are vectors of pathogenic viruses that cause major human illnesses including dengue, yellow fever and chikungunya. Both mosquito species are expanding their geographic distributions and now occur worldwide in temperate and tropical climates. Collection of eggs in oviposition traps (ovitraps) is commonly used for monitoring and surveillance of container-inhabiting Aedes populations by public health agencies charged with managing mosquito-transmitted illness. Addition of an organic infusion in these traps increases the number of eggs deposited. Gravid females are guided to ovitraps by volatile chemicals produced from the breakdown of organic matter by microbes.MethodsWe previously isolated and cultured 14 species of bacteria from attractive experimental infusions, made from the senescent leaves of canebrake bamboo (Arundinaria gigantea). Cultures were grown for 24 h at 28 °C with constant shaking (120 rpm) and cell densities were determined with a hemocytometer. Behavioral responses to single bacterial isolates and to a mix of isolates at different cell densities were evaluated using two-choice sticky-screen bioassay methods with gravid Ae. aegypti and Ae. albopictus.ResultsIn behavioral assays of a mix of 14 bacterial isolates, significantly greater attraction responses were exhibited by Ae. aegypti and Ae. albopictus to bacterial densities of 107 and 108 cells/mL than to the control medium. When we tested single bacterial isolates, seven isolates (B1, B2, B3, B5, B12, B13 and B14) were significantly attractive to Ae. aegypti, and six isolates (B1, B5, B7, B10, B13 and B14) significantly attracted Ae. albopictus. Among all the isolates tested at three different cell densities, bacterial isolates B1, B5, B13 and B14 were highly attractive to both Aedes species.ConclusionsOur results show that at specific cell densities, some bacteria significantly influence the attraction of gravid Ae. aegypti and Ae. albopictus females to potential oviposition sites. Attractive bacterial isolates, when formulated for sustained release of attractants, could be coupled with an ovitrap containing a toxicant to achieve area-wide management of Aedes mosquitoes.
Highlights
The mosquitoes Aedes aegypti and Aedes albopictus are vectors of pathogenic viruses that cause major human illnesses including dengue, yellow fever and chikungunya
Positive oviposition responses were exhibited by gravid Aedes aegypti and Culex quinquefasciatus to bacteria isolated from hay infusion [15]
Response of gravid mosquitoes to a mix of bacterial isolates We evaluated the responses of gravid females of two mosquito species to four different cell densities of a mixture of 14 bacterial species that we had isolated previously from water infusions of canebrake bamboo leaves (Table 1)
Summary
The mosquitoes Aedes aegypti and Aedes albopictus are vectors of pathogenic viruses that cause major human illnesses including dengue, yellow fever and chikungunya. Both mosquito species are expanding their geographic distributions and occur worldwide in temperate and tropical climates. (Stegomyia) albopictus (Skuse) are the principal mosquito vectors of dengue fever, yellow fever and chikungunya viruses on a global basis [1] These Stegomyia mosquitoes are dayactive and lay eggs in domestic water-filled containers [2]. Positive oviposition responses were exhibited by gravid Aedes aegypti and Culex quinquefasciatus to bacteria isolated from hay infusion [15]. Recent reviews describe the use of microbial volatiles by mosquitoes as chemical cues to locate oviposition sites containing nutrient resources [19, 20]
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