13 

 [15]. It is certain, however, that carbon dioxide activates flight in mosquitoes [7,17]. 



Experiments involving removal of carbon dioxide from exhaled breath showed 



reduction in mosquito attraction to a host; however, it is not certain that carbon 



dioxide was the only volatile compound removed in such a study [7]. The range of 



effectiveness of carbon dioxide has been shown to extend beyond 60 ft, possibly up 



to 120 ft [15]. 



Studies involving Ae. aegypti palpal sensilla showed logarithmic phasic 

 response to carbon dioxide from 0.01% to approximately 0.5% and that these sensilla 

 can detect changes in concentration of 0.01% carbon dioxide. Saturation occurs 

 above 0.5%, with little or no additional response at higher carbon dioxide 

 concentrations. Exhaled human breath contains approximately 4.5% carbon dioxide 

 compared to 0.01-0.10% found in the surrounding air [7]. Therefore, detection of 

 carbon dioxide plumes by the mosquito is possible after a two order-of-magnitude 

 dilution of carbon dioxide in exhaled breath. An additional note is that upon 

 palpectomy, mosquitoes showed little or no response to carbon dioxide at any 

 concentration level [4,7,16]. 

 Sound 



Sound (wingbeat frequency) is a short-range attractant for orientation of 

 males to females for purposes of mating [4,8,27]. The males of almost all species of 

 mosquito have a wingbeat frequency which is approximately double that of the 

 female [8,27]. The few species not employing sound as a short-range cue have 

 approximately equivalent wingbeat frequencies for both genders. Sound level is also 



