A BIMODAL RESPONSE TO DIETARY SUGARS BY AN INSECT

¹ Department of Entomology, University of Wisconsin, Madison 6, Wisconsin

1. A study of the feeding behavior of newly hatched, previously unfed larvae of the European corn borer has shown that dietary sugar concentration has a pronounced and quantitatively measurable effect on such behavior.

2. The larvae tended to prolong their feeding in proportion to the dietary sugar concentrations.

3. The responses to sugar concentrations above a positive response threshold of about 0.001 M were in agreement with Fechner's law over the concentration range tested. There was a small but significant negative feeding response toward sugar concentrations below 0.001 M and down to 0.0002 M.

4. The experimental results obtained indicate that this organism displays a bimodal response to glucose, sucrose, and fructose, in which the modes differ in sign and are dependent upon the concentrations employed. The response spectrum of the insect toward the sugars tested appears to be parallel, if not directly comparable, to the human taste spectrum for sucrose.