Olfactory responses and field attraction of mosquitoes to volatiles from Limburger cheese and human foot odor.

Olfactory responses of female Aedes aegypti (Linnaeus) to various odor stimuli were studied in a dual-port olfactometer. Responses (i.e., the percent of ca. 75 available female mosquitoes in flight chamber entering each olfactometer port) were studied toward clean conditioned air (control), human foot skin emanations (collected on socks by wearing them for three days), human hand, and Limburger cheese. Mean percent response was greatest to the human hand (80.1%), followed by the human worn sock (66.1%), Limburger cheese (6.4%), and control (< 0.1%). In field studies the worn sock alone attracted very few mosquitoes but a synergistic response occurred to the sock + carbon dioxide baited traps for most species of mosquitoes in six genera (Aedes, Anopheles, Coquillettidia, Culex, Culiseta, and Psorophora). This synergistic effect persisted even when the socks were exposed to environmental conditions for eight consecutive days. Limburger cheese alone did not attract mosquitoes to traps compared to unbaited traps, and there appeared to be a slight repellent effect for most mosquito species when used in combination with carbon dioxide.