Decreased sensitivity of mixed-function oxidases from papilio polyxenes to inhibitors in host plants

J. J. Neal, May R Berenbaum

Research output: Contribution to journalArticlepeer-review


Caterpillars of Papilio polyxenes, the black swallowtail, feed on umbellifers that contain both toxic furanocoumarins and methylenedioxyphenyl compounds such as myristicin and safrole. These phytosynergists enhance the toxicity of furanocoumarins by inhibiting mixed-function oxidases (MFOs), the detoxification enzymes responsible for metabolizing furanocoumarins. In model substrate assays, MFOs from P. polyxenes are twice as active as MFOs from Heliothis zea, a generalist herbivore not adapted to feeding on either furanocoumarins or furanocoumarin/phytosynergist combinations. P. polyxenes MFOs are 10 and 46 times less sensitive to inhibition by myristicin and safrole, respectively, than H. zea MFOs and eight times less sensitive to inhibition by safrole than MFOs from Papilio troilus, a closely related species that does not encounter furanocoumarin/phytosynergist combinations in its diet. Higher MFO activity and decreased sensitivity to MFO inhibitors are important adaptations that allow black swallowtail caterpillars to feed on many umbelliferous plants.

Original languageEnglish (US)
Pages (from-to)439-446
Number of pages8
JournalJournal of Chemical Ecology
Issue number1
StatePublished - Jan 1989


  • Heliothis zea
  • Lepidoptera
  • Papilio polyxenes
  • Papilio troilus
  • Papilionidae
  • methylenedioxyphenyl
  • mixed-function oxidase inhibition
  • myristicin
  • noctuidae
  • safrole
  • xanthotoxin

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry


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