Document Detail

Using stable isotopes to reveal shifts in prey consumption by generalist predators.
MedLine Citation:
PMID:  16826987     Owner:  NLM     Status:  MEDLINE    
The effectiveness of generalist predators in biological control may be diminished if increased availability of alternative prey causes individual predators to decrease their consumption of crop pests. Farming practices that enhance densities of microbidetritivores in the detrital food web can lead to increased densities of generalist predators that feed on pest species. The ability to predict the net biocontrol impact of increased predator densities depends upon knowing the extent to which individual predators may shift to detrital prey and feed less on crop pests when prey of the detritus-based food web are more abundant. We addressed this question by comparing ratios of stable isotopes of carbon (delta13C) and nitrogen (delta15N) in generalist ground predators and two types of prey (crop pests and microbidetritivores) in replicated 8 x 8 m cucurbit gardens subjected to one of two treatments: a detrital subsidy or no addition of detritus (control). Small sheet-web spiders (Linyphiidae) and small wolf spiders (Lycosidae) had delta13C values similar to those of Collembola in both the detrital and control treatments, indicating that small spiders belong primarily to the detrital food web. In control plots the larger generalist predators had delta13C values similar to those of the major insect pests, consistent with their known effectiveness as biocontrol agents. Adding detritus may have caused delta13C of one species of large wolf spider to shift toward that of the microbi-detritivores, although evidence is equivocal. In contrast, another large wolf spider displayed no shift in delta13C in the detrital treatment. Thus, stable isotopes revealed which generalist predators will likely continue to feed on pest species in the presence of greater densities of alternative prey.
David H Wise; Denise M Moldenhauer; Juraj Halaj
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Ecological applications : a publication of the Ecological Society of America     Volume:  16     ISSN:  1051-0761     ISO Abbreviation:  Ecol Appl     Publication Date:  2006 Jun 
Date Detail:
Created Date:  2006-07-07     Completed Date:  2006-10-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9889808     Medline TA:  Ecol Appl     Country:  United States    
Other Details:
Languages:  eng     Pagination:  865-76     Citation Subset:  IM    
Department of Entomology, University of Kentucky, Lexington, Kentucky 40546-0091, USA.
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MeSH Terms
Carbon Isotopes / analysis*
Crops, Agricultural / chemistry
Nitrogen Isotopes / analysis*
Predatory Behavior*
Reg. No./Substance:
0/Carbon Isotopes; 0/Nitrogen Isotopes

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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