Aristolochic acids as a defensive substance for the aristolochiaceous plant-feeding swallowtail butterfly, pachliopta aristolochiae interpositus

The chemical constituents isolated from every stage of the Taiwanese swallowtail butterfly, Pachliopta aristolochiae interpositus, were studied and compared with the constituents of the insect feeding plant, A. cucurbitifolia. Two aristolochic acid derivatives (1 and 4) and three aristolactam analogues (5, 6, and 7) were isolated from the larval osmeterial fluid and larvae of the insect. In addition, four purines (2, 3, 13, and 14), one indole alkaloid (11), one steroid (10), two benzenoids (8 and 9) and allantoin (12) were also isolated from the insect. Among these compounds, Aristolochic acid -I (AA-I, 1) was detected in all life stages of the insect, especially in the larval osmeterial fluid. The studies confirm that the toxic AAs are used as larval feeding stimulants and deterrent allomones against birds.