Evolutionary Ecology

, Volume 5, Issue 2, pp 136-145

First online:

Parthenocarpic fruits in wild parsnip: Decoy defence against a specialist herbivore

  • Arthur R. ZangerlAffiliated withDepartment of Entomology, University of Illinois
  • , May R. BerenbaumAffiliated withDepartment of Entomology, University of Illinois
  • , James K. NitaoAffiliated withDepartment of Entomology, Michigan State University

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Parthenocarpy, the production of fruits without viable seeds, is a widespread phenomenon in plants. While failure to effect pollination or fertilization is often cited as the cause of parthenocarpy, this explanation alone is inadequate to explain why plants produce, maintain and further develop fruits. Wild parsnips (Pastinaca sativa) frequently produce parthenocarpic fruit. When parsnip webworms (Depressaria pastinacella), specialist feeders on wild parsnip, were given choices between normal fruit and parthenocarpic fruit, they exhibited a strong preference for parthenocarpic fruit. However, on parthenocarpic fruit, insects fed less efficiently and grew more slowly than insects fed normal fruit. Parthenocarpic fruits, then, may act as decoys that divert herbivores away from fruits that contain plant offspring.


Parthenocarpy fruits defence wild parsnip Pastinaca sativa parsnip webworm Depressaria pastinacella furanocoumarins decoys