Chemical defense in the zebra swallowtail butterfly, Eurytides marcellus, involving annonaceous acetogenins

Few herbivores feed on the foliage of the North American paw paw tree, Asim ina triloba; notable exceptions are the larvae of the zebra swallowtail but terfly, Eurytides marcellus. Toxic annonaceous acetogenins, produced by A.. triloba, are responsible for the relative unpalatability of the leaves. Ac etogenins found in A. triloba extracts are potent pesticidal and antineopla stic agents and have emetic activity in vertebrates. In this study, partiti oned aqueous MeOH fractions of the bioactive CH2Cl2 extracts, of freeze-dri ed and pulverized larvae, and of mature butterflies revealed acetogenin con tent through the use of HPLC coupled to tandem MS (LC-MS/MS). This sensitiv e technique provides an uncomplicated method for the detection of trace com pounds and, in this instance, has confirmed tissue presence of acetogenins that serve a probable role as chemical defense agents against bird predatio n in zebra swallowtail larvae and adults.