Impact of flowering buckwheat on Lepidopteran cabbage pests and their parasitoids at two spatial scales

Jana C. Lee, George E. Heimpel

Research output: Contribution to journalArticlepeer-review

110 Scopus citations

Abstract

We assessed the potential of annual buckwheat, Fagopyrum esculentum Moench, to lead to improved parasitism of lepidopteran cabbage pests over four years. Pest, parasitism, and hyperparasitism rates were monitored in replicated cabbage plots (12 x 20 m) with or without 3 m wide buckwheat borders from 2000 to 2003. Floral borders did not significantly increase egg, larval, or pupal densities of cabbage looper, Trichoplusia ni (Hübner), imported cabbageworm, Pieris rapae (L.), or diamondback moth, Plutella xylostella (L.). Buckwheat increased parasitism rates by Voria ruralis (Fallen) on T. ni larvae and Cotesia rubecula (Marshall) on P. rapae larvae over four years. Parasitism by Diadegma insulare (Cresson) on P. xylostella larvae was higher in buckwheat than control plots in the first year, and parasitism by Euplectrus plathypenae (Howard) on T. ni larvae was lower in buckwheat than control plots in the second year. The hyperparasitoid Conura side (Walker) attacked D. insulare all four years, but buckwheat did not affect hyperparasitism rates. The effect of spatial scale on pest densities and parasitism in 2001 was evaluated by comparing plots separated at least 67 m (nearby) versus 800 m apart (isolated). T. ni pupae and P. rapae eggs and pupae were more abundant in plots in closer proximity, whereas P. xylostella densities did not vary by the spatial separation of plots. Tachinids and Pteromalus puparum (L.) attacked more P. rapae in nearby plots. E. plathypenae responded to the treatment x scale interaction, parasitizing more in control than buckwheat when plots were isolated but not when plots were nearby.

Original languageEnglish (US)
Pages (from-to)290-301
Number of pages12
JournalBiological Control
Volume34
Issue number3 SPEC. ISS.
DOIs
StatePublished - Sep 2005

Bibliographical note

Funding Information:
We thank Tim Winkler, Kathy Kurtz, Gregory Miller, and Carmen Gavin for assistance in sampling and rearing. We thank John Luhman for help with parasitoid identifications and Eric Grissell at the USDA Sytematic Entomology Laboratory for hyperparasitoid identifications. Kimon and Jim Karelis at UMORE assisted us in the field. This research was funded by USDA NRI Grant #9802906, a USDA North Central Regional IPM grant to G.E.H., Community Genetics student research grant, Louise T. Dosdall, New Student and Doctoral Dissertation Fellowship to J.C.L., and the University of Minnesota Agricultural Experiment Station.

Keywords

  • Conura side
  • Copidosma floridanum
  • Cotesia glomerata
  • Cotesia rubecula
  • Diadegma insulare
  • Euplectrus plathypenae
  • Floral nectar
  • Habitat diversification
  • Hyperparasitism
  • Pieris rapae
  • Plutella xylostella
  • Pteromalus puparum
  • Trichoplusia ni
  • Voria ruralis

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