Control of Antennal Hair Erection in Male Mosquitoes

The long fibrillae, or hairs, on the antennae of male mosquitoes are essential for the detection of the female flight sound, the sole sexual attractant. In Anopheles stephensi, as in many other genera and species, these long hairs are recumbent on the shaft of antenna during the daytime and become briefly erect at dusk, coincident with swarming and mating activity. Evidence is presented that erection of the antennal hairs is under direct nervous control. Isolated antennae can be induced to erect their hairs only in the presence of α-adrenergic agonists, and this response is blocked in the presence of the α-adrenergic blocking drug, phentolamine. Thus, a cell surface receptor, resembling the vertebrate α-adrenergic receptor, probably mediates the response to the natural neurotransmitter. The action of α-adrenergic drugs is mimicked by cyclic nucleotides and also by theophylline.