Abstract
The Stimulating activity of twenty eight sugars and related compounds have been tested behaviorally on the tarsal chemoreceptors of the cabbage butterfly, Pieris rapae crucivora BOISDUVAL. Among these, D-fructose, L-fucose and sucrose showed strong stimulating activity, but the females showed higher levels of response than the males to these sugars. Based on the RC50 for these three sugars, the following series of stimulating effectivenes is obtained : L-fucose>sucrose>D-fructose. Furthermore, from the tarsal response to D-fructose and related compounds, to raffinose, and to sucrose, it is suggested that there is stringent specificity in the relationship between the stimulating ability of D-fructose and the chemoreceptors of the cabbage butterfly. Only the three sugars, L-fucose, D-fructose and sucrose, showed very higher intake amount than other sugars. The intake amount of all other sugars was about equal to or larger than that of water. Therefore, it is concluded that L-fucose, D-fructose and sucrose have higher stimulating activity to the tarsal, proboscis-tip and internal chemoreceptors. Based on these results, relationship between the stimulating activity of sugars and kinds of specific gustatory receptor site is discussed. Although L-fucose showed the highest stimulating effectiveness on the tarsal and apparently on proboscis-tip and internal chemoreceptors, its nutritive value was very low.
