Herbivore response to vegetational diversity: Spatial interaction of resources and natural enemies

Jason P. Harmon, Erin E. Hladilek, Jennifer L. Hinton, Timothy J. Stodola, D. A. Andow

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Vegetational diversity in agricultural systems is predicted to reduce herbivore populations, but we observed the opposite effect: higher nymph population densities of a functionally monophagous herbivore, the squash bug, Anasa tristis (Hemiptera: Coreidae) in a vegetationally diverse squash-bean-corn polyculture than in a squash monoculture. We examined spatial and temporal aspects of squash bug and predator populations in relation to vegetational diversity. Average colonization, oviposition, and mortality rates for the herbivore were similar in monocultures and polycultures. In the polyculture, however, we found that squash bugs eggs were highly aggregated on plants on the outer edges of plots. Predation was also lower on plants near the edges, allowing the large aggregations of eggs found in the polyculture to escape predation and ultimately produce more squash bugs. Spatial interactions between herbivores and natural enemies may underlie some of the general effects of vegetational diversity on herbivores.

Original languageEnglish (US)
Pages (from-to)75-81
Number of pages7
JournalPopulation Ecology
Volume45
Issue number2
DOIs
StatePublished - Aug 1 2003

Keywords

  • Anasa tristis
  • Carabidae
  • Polyculture
  • Predation
  • Resource concentration hypothesis
  • Spatial patterns

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