Sensitivity to chemically diverse phagostimulants in a single gustatory neuron of a polyphagous caterpillar

Caterpillars of the arctiid moth, Giammia geneura, are polyphagous, but spe cies of Plantago are amongst their preferred food plants. A neuron in the m edial styloconic sensillum on the galea has been shown to have a general ph agostimulatory function. Experiments with binary mixtures and cross-adaptat ion have demonstrated that it responds to some sugars, to several amino aci ds, and also to catalpol. Catalpol is a plant secondary compound in Plantag o and a phagostimulant for the caterpillars. The possible significance of c ombining sensitivity to nutrient compounds with sensitivity to a secondary compound is discussed.