Chemical Factors Determining the Choice of Food Plants by Papilio Larvae

Abstract

A series of complex chemical compounds present in the essential oils of Umbelliferae impart characteristic odors to the plants of this family. Species of Papilio which fefed on Umbelliferae are attracted by these chemicals. The larvae are attracted by specific compounds not by groups of related compounds. The olfactory sense in these larvae can discriminate among closely related odors, and apparently larvae react to compounds because of the odors as man perceives them and not because of any other properties of the compounds; Although the attractant chemicals are most common in Umbelliferae, they occur in other families. Papilios now feeding on umbelliferous plants originally fed upon Rutaceae. The transition from one plant family to the other took place because of the presence of identical attractant chemicals in both families. The present distribution of the genus Papilio is related in part to the distribution of the host plants.