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Small-scale spatial pattern of web-building spiders (Araneae) in alfalfa: Relationship to disturbance from cutting, prey availability, and intraguild interactions

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Author

Summary, in English

Understanding the development of spatial patterns in generalist predators will improve our ability to incorporate them into biological control programs. We studied the small-scale spatial patterns of spider webs in alfalfa by analyzing the relationship between web locations over distances ranging from 4 to 66 cm. Using a coordinate-based spatial statistic (O-ring) and assuming a heterogeneous distribution of suitable web sites, we analyzed the impact of cutting and changes in spider abundance on web distribution. We analyzed the influence of small-scale variation in prey availability by comparing web distributions to the pattern of sticky-trap captures of Aphididae and Diptera described by a count-based spatial statistic (SADIE). Cutting of alfalfa reduced the overall density of web-building spiders but had no immediate impact on the spatial distribution of their webs. Availability of aphids was highest before the alfalfa was cut and was clumped at a scale of 66 cm. Spider webs, however, were not clumped at any scale or date. In contrast, webs were regularly distributed at smaller distances (<20 cm) immediately before and after cutting. Because cursorial and web-building spiders were most active during this period, we hypothesize that the development of small-scale regularity in web locations was driven by intraguild interactions. Our results suggest that intraguild interactions contribute to the development of small-scale spatial patterns of spider webs in alfalfa. Variation in prey availability may have more of an influence on web distribution in crops with a different vegetation structure or if patterns are studied at larger spatial scales.

Department/s

Publishing year

2007

Language

English

Pages

801-810

Publication/Series

Environmental Entomology

Volume

36

Issue

4

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Ecology

Keywords

  • predator-prey association
  • biological control
  • generalist predators

Status

Published

ISBN/ISSN/Other

  • ISSN: 1938-2936