Aedes aegypti: Sensilla trichodea and stimulus-conducting structures

Abstract

Much of the morphology of the olfactory sensilla on the antennae of the mosquito Aedes aegypti (L.) has been described, however little is known about the fate of odour molecules once they have been adsorbed onto the surfaces of sensilla. A stimulus-conducting system of pores, pore kettles, and pore tubules has been described for the sensilla trichodea (olfactory hairs) of several insects but not mosquitoes. Scanning electron microscopy was used to identify the s. trichodea of Ae. aegypti and to attempt visualization of their pore openings. Chemical fixation, cryopreparation, freeze drying, and negative staining, with high resolution transmission electron microscopy (TEM), were used to locate putative stimulus-conducting structures associated with the pores. TEM sections using Dalton's fixative or freeze drying showed pores and pore tubules, whereas pore tubules were poorly preserved in cryoprepared sections. The putative stimulus-conducting structures were clearly demonstrated by negative staining of whole sensilla which was quick and easy. The current hypothesis of olfactory stimulus conduction is extended to include Ae. aegypti.