Chemical Defense in the Zebra Swallowtail Butterfly, Eurytides marcellus, Involving Annonaceous Acetogenins

Abstract

Few herbivores feed on the foliage of the North American paw paw tree, Asimina triloba; notable exceptions are the larvae of the zebra swallowtail butterfly, Eurytides marcellus. Toxic annonaceous acetogenins, produced by A. triloba, are responsible for the relative unpalatability of the leaves. Acetogenins found in A. triloba extracts are potent pesticidal and antineoplastic agents and have emetic activity in vertebrates. In this study, partitioned aqueous MeOH fractions of the bioactive CH2Cl2 extracts, of freeze-dried and pulverized larvae, and of mature butterflies revealed acetogenin content through the use of HPLC coupled to tandem MS (LC-MS/MS). This sensitive technique provides an uncomplicated method for the detection of trace compounds and, in this instance, has confirmed tissue presence of acetogenins that serve a probable role as chemical defense agents against bird predation in zebra swallowtail larvae and adults.