For a second role, CO 2 also helps female mosquitoes orient themselves with respect to a potential host. While most olfactory receptors are located on the antennae of insects, the mosquito CO 2 receptors are located on the labial palps. The olfactory responses to CO 2 are integrated with other olfactory information to produce the host seeking behaviors of female mosquitoes. 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.