HERBIVORE AVOIDANCE OF DIGITALIS EXTRACTS IS NOT MEDIATED BY CARDIAC-GLYCOSIDES

This study was conducted to determine whether avoidance of digitalis ( Digitalis purpurea) by mountain beaver (Aplodontia rufa) is induced by toxic cardiac glycosides. High-performance liquid chromatography and behavioral assays were used to relate animal responses with the presen ce of common cardiac glycosides in several digitalis extracts. Statist ical analyses of multiple-choice tests showed no correlation between c ardiac glycoside content and mountain beaver avoidance of apple cubes treated with digitalis extracts. Therefore, we concluded that known to xic cardiac glycosides were not responsible for chemosensory cues that inhibited intake of food treated with digitalis extracts. These resul ts suggest that digitalis is a source of an effective nontoxic herbivo re repellent.