Ammonia and carbon dioxide:: Quantitation and electroantennogram responses of Caribbean fruit fly, Anastrepha suspensa (Diptera: Tephritidae)

A Fourier transform infrared (FTIR) spectroscopic method was developed to quantify ammonia (NH3) and carbon dioxide (CO2) to facilitate accurate determination of antennal sensitivity of adult Caribbean fruit flies, Anastrepha suspensa (Loew), to these compounds. Electroantennogram (EAG) recordings were made from antennae of flies that were exposed to known quantities of each of the pure gases and to mixtures of these gases. EAG response to volumetric dilutions of saturated vapor from a commercially available ammonium bicarbonate lure was determined, and FTIR analysis was used to measure the amount of NH3 and CO2 in the samples. Maximal EAG responses were elicited with doses >= 24 mu g NH3 and >= 57 mu g CO2. Mean female response was greater than male response to substrates that included CO2. For both sexes, EAG response to NH3 was greater than response to COD When NH3 and CO2 were combined either as a mixture of pure gases or as vapor emitted from the lure, the EAG response was approximately equal to the sum of the individual responses to the two compounds. A polynomial regression was the best fit for describing antennal response to ammonia, carbon dioxide, and mixtures of these chemicals whether obtained from pure gas sources or from commercial lures.