FOOD-FINDING BY POLYPHAGOUS ARCTIID CATERPILLARS LACKING ANTENNAL AND MAXILLARY CHEMORECEPTORS

Abstract

AbstractPatterns of locomotion of arctiid caterpillars,Diacrisia virginicaFabr., deprived of all external chemosensory organs were recorded in a field where there was patchy distribution of two of the most favored food plants,Plantago majorL. andTaraxacum officinaleWalker, on a background of grass and mixed forbs. Each track traced in the field was retraced on a digitizing tablet from its point of origin in the center of a circle of 30 cm radius to the circumference. The length of the path was a measure of tortuosity. The patterns of paths followed by normal, antennectomized, maxillectomized, and antennectomized + maxillectomized larvae were compared. No differences in meander were found. The ability of larvae of each class to locate, discriminate among, and feed upon food plants was tested in field-plot tests and cafeteria tests. Different degrees of chemosensory deprivation did not affect ability to locate and begin feeding on plants but did impair ability to discriminate among species. Execution of normal patterns of meandering by chemosensorily deprived larvae and successful encounters with food plants support the hypothesis that food-related search behavior by this species of caterpillar is neither initiated nor steered by chemical stimuli provided by food plants.