Effects of linear furanocoumarins on an adapted specialist insect (Papilio polyxenes)

Abstract. 1. Examination of phytochemical literature reveals that a disproportionately large number of hostplants for species in the genus Papilio Section II, and in particular the machaon complex, contain linear furanocoumarins. 2. Although the linear furanocoumarin xanthotoxin is known to be toxic to generalist lepidopterous larvae, it failed to affect adversely the growth and survivorship of Papilio polyxenes, a member of the P.machaon complex that feeds primarily on Umbelliferae containing furanocoumarins, when incorporated into an artificial diet. 3. On the contrary, growth rate and weight gain were significantly improved in the presence of xanthotoxin. 4. It is proposed, based on this experimental evidence and on hostplant utilization patterns, that furanocoumarins play a significant role in the behavioural and biochemical adaptation of Papilio species to their umbelliferous hosts.