Abstract
Single antennal olfactory cells of the Japanese dung beetle, Geotrupes auratus, which releases food searching behavior in response to cow dung odor, responded well to dung odor and five components of dung specific odorant, namely-2-butanone, phenol, p-cresol, indole and skatole. The impulses were 2-20 mV in height and there were 10-20 impulses per one stimulus of about 3 sec duration. Sensillum cells were classified into two groups based on the type of response to odor components. One was the R-Type I which responded only to 2-butanone ("specialist"), and the other group, the R-Type II, showed responses not only to 2-butanone but also to the other four component odors ("generalist"). Both R-Type I and II cells increased in impulse frequency or number with increase of the concentration of each odorant. It seems that the dung beetles orient toward food through the R-Type I olfactory sensillum cells responding only to 2-butanone which is the most volatile among the components, and that R-Type II cells may contribute to the behavioral Function after arrival at the food.
