Recognizing that information from the palps is integrated with information from the antennae, we note the integration of information from the peripheral system is integrated in the central nervous system. We also note CO 2 is a necessary component of host odors. Lactic acid is a ubiquitous product of energy metabolism. While high levels of LA are produced under anaerobic conditions, low levels are also produced under aerobic conditions. LA evaporates from the skin of humans and other mammals.
Mosquitoes have LA receptors on the sensilla basiconica, or grooved pegs, on their antennae.
The LA receptors are specific to lactic acid, with very little activity in response to other small, organic acids. There are actually two LA receptors in the antennae of female mosquitoes. One of the receptors is stimulatory and the other is inhibitory, that is, there is increased frequency of nerve impulses in one and a reduced frequency in the other. The biological significance of the inhibitory lactic acid receptor is not well understood. The physiology of the LA receptor is of some interest because the expression of the LA receptor sensitivity coincides with host-seeking behavior.