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Antennal sensilla of two female anopheline sibling species with differing host ranges

DOI: 10.1186/1475-2875-5-26

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Scanning electron and light microscopy were used to examine the antennae ultrastructures of adult female An. gambiae s.s. and An. quadriannulatus. Sensory structures, called sensilla, were categorized and counted; their distributions are reported here as well as densities calculated for each species.Both An. gambiae s.s. and An. quadriannulatus bear five classes of sensilla on their antennae: chaetica (bristles), trichodea (hairs), basiconica (pegs), coeloconica (pitted pegs), and ampullacea (pegs in tubes). Female An. quadriannulatus antennae have approximately one-third more sensilla, and a proportionally larger surface area, than female An. gambiae s.s. antennae.The same types of sensilla are found on the antennae of both species. While An. quadriannulatus has greater numbers of each sensilla type, sensilla densities are very similar for each species, suggesting that other factors may be more important to such olfactory-driven behaviours as host preference.Odors are the principle sensory signals that direct female mosquitoes to their preferred blood meal hosts [1,2]. Antennae of adult mosquitoes bear numerous sensory structures called sensilla, which are the physical sites of chemical detection. Within sensilla, olfactory signal transduction relies on odorant receptor proteins localized on the dendritic membranes of olfactory receptor neurons to initiate the events that ultimately lead to the perception of both the quality and the quantity of odors. Behavioural responses to volatile cues, including host finding by female mosquitoes, are critical components of vectorial capacity, the ability of an insect to transmit disease [2]. Two closely related mosquito sibling species, An. gambiae s.s. and An. quadriannulatus, display very different patterns of blood meal host preference. An. gambiae s.s. exhibits a high degree of anthropophily, while An. quadriannulatus exhibits strong zoophily [2]. Indeed, the strong preference for human blood meals by An. gambiae s.s. fema


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