Physical and ant-mediated refuges from parasitism: Implications for non-target effects in biological control

Kris A.G. Wyckhuys, Robert L. Koch, George E. Heimpel

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32 Scopus citations


A promising natural enemy for release against the Asian soybean aphid, Aphis glycines Matsumura, in North America is the aphidiine braconid wasp Binodoxys communis (Gahan). The aphid Aphis monardae Oestlund, a native of North America's tall-grass prairies, is a non-target species that may be at risk from releases of B. communis. This paper describes ecological facets of A. monardae populations in their native habitat that could protect them from attack by this exotic biological control agent. In prairie habitats, A. monardae populations aggregate in flower heads of their host plant, Monarda fistulosa L. On this host plant, aphids are also commonly tended by four ant species, and ant-tended colonies are larger than un-attended colonies. Laboratory studies showed that parasitism rates of A. monardae by B. communis are significantly higher on vegetative M. fistulosa than on M. fistulosa flower heads. In addition, attendance of A. monardae by the ant Lasius neoniger Emery significantly decreased parasitism by B. communis. Ants attacked and killed host-seeking adult parasitoids, and preyed upon B. communis mummies. No evidence was found that B. communis reared from A. monardae are less susceptible to attack by ants than parasitoids reared from A. glycines. M. fistulosa flower heads and attendance by L. neoniger may act as refuges for A. monardae against B. communis. Our work describes spatial refuges as ecological filters that separate non-target organisms from exotic natural enemies. Implications for classical biological control of A. glycines are discussed.

Original languageEnglish (US)
Pages (from-to)306-313
Number of pages8
JournalBiological Control
Issue number3
StatePublished - Mar 2007

Bibliographical note

Funding Information:
We thank Chris Kulhanek, Jo Barta and Mark Anderson for help with field research and laboratory experiments. We also thank David Voegtlin for providing A. monardae, Kim Hoelmer for collecting B. communis, and Keith Hopper for culturing B. communis before we brought it to Minnesota. James C. Trager identified ant species that were collected in the field. Steve A. Kells provided information for maintaining an ant colony under laboratory conditions. This work was funded in part by the multi-state USDA-RAMP project, in part by the North Central Soybean Research Council, and in part by the Minnesota Agricultural Experiment Station. We are also grateful to Bob Djupstrom and the Minnesota DNR, Scientific and Natural Areas Program for their granting permission to conduct research in Minnesota prairie sites.


  • Ant-parasitoid interactions
  • Binodoxys communis
  • Classical biological control
  • Lasius neoniger
  • Non-target effects
  • Parasitism
  • Soybean aphid
  • Spatial refuges


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