Web-site selection strategies of linyphiid spiders in alfalfa: Implications for biological control

James D. Harwood, John J. Obrycki

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Site-specific foraging can enhance the ability of generalist predators to provide effective and sustainable levels of pest control in agroecosystems. This can result from increased growth rates, higher population densities, and improved capture frequencies of pests at high prey density microsites. We tested the hypothesis that linyphiid spiders would exhibit microhabitat-specific web-site selection strategies in alfalfa. This was predicted to result in high prey densities at web-sites compared to paired non-web-sites through direct, or indirect, selection of prey-rich habitats. A total of 22,242 potential prey items were collected from mini-sticky traps located at 896 microsites. Web-centered mini-sticky traps on the ground, representative of Erigone autumnalis Emerton (Araneae: Linyphiidae) webs, captured similar numbers of potential prey as paired non-web-centered traps nearby. However, aerial sticky traps at web-sites of Bathyphantes pallidus (Banks) (Araneae: Linyphiidae) contained significantly more Diptera and Empoasca fabae (Harris) (Homoptera: Cicadellidae) than paired non-web-centered sticky-traps. Prey activity-densities also varied between web-sites of E. autumnalis and B. pallidus. Diptera were dominant at aerial microsites of B. pallidus whilst Collembola were abundant on ground-based traps of E. autumnalis. These results suggest that in alfalfa, the pressure for selecting prey-rich web-sites by erigonine spiders is low, but B. pallidus exhibits a selective web-location strategy targeted towards high quality dipteran prey. These sites also captured large numbers of E. fabae, a major pest of alfalfa, thus implicating aerial-based linyphiines as valuable predators in biological control.

Original languageEnglish
Pages (from-to)451-467
Number of pages17
Issue number4
StatePublished - Aug 2007

Bibliographical note

Funding Information:
The authors would like to thank two anonymous reviewers and the editor for their valuable suggestions. JDH and JJO are supported by the Kentucky Agricultural Experiment Station State Project KY099004. This is publication number 06-08-043 of the Kentucky Agricultural Experiment Station.


  • Alternative prey
  • Araneae
  • Collembola
  • Empoasca fabae
  • Food webs
  • Generalist predators
  • Linyphiidae
  • Microsite selection
  • Predator-prey interactions

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Insect Science


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