ODOUR-GUIDED HOST FINDING of MOSQUITOES: IDENTIFICATION of NEW ATTRACTANTS on HUMAN SKIN

Abstract:
The basic principles of olfaction in mosquito-host interaction is presented using Aedes aegypti. Olfactometer bioassays investigated which compounds of the complex blend of human emanations play a role in the attraction, and which factors make some hosts more attractive than others. Beside L-(+)-lactic acid and carbon dioxide, ammonia, and short-chain fatty acids contribute to the attractive. The key compound is lactic acid, which is produced by eccrine sweat glands. Other components also contributed to the high attractiveness of a synthetic mixture. Comparing the hands of different humans we verified that certain individuals are more attractive to mosquitoes than others. The addition of lactic acid to the odour of less attractive people significantly increased their attractiveness and changed the mosquitoes’ preference. The importance of lactic acid was confirmed in odour samples from different animals. The samples did not contain significant amounts of lactic acid and elicited only weak behavioural responses. The attractiveness of these animal odours increased when lactic acid was added. These findings emphasise the key role of lactic acid for A. aegypti: it is only a weak attractant by itself, but an essential element in the pattern of kairomones. Using this artificial odour blend in CO2 baited mosquito traps could provide an important tool for the surveillance of mosquito population in vector control.