Document Detail

Predation or scavenging? Thoracic muscle pH and rates of water loss reveal cause of death in arthropods.
MedLine Citation:
PMID:  20639425     Owner:  NLM     Status:  MEDLINE    
The difficulty of directly observing predatory events hinders a complete understanding of how predation structures food webs. Indirect approaches such as PCR-based and isotopic analyses clarify patterns of resource consumption but fail to distinguish predation from scavenging. Given that facultative scavenging is a ubiquitous and phylogenetically widespread foraging strategy, an improved ability to discriminate prey from carrion is needed to enhance an understanding of the demographic effects of consumption and the true nature of trophic interactions. Using physiological properties of muscle tissue - specifically pH and rate of water loss - we develop a novel method to discriminate prey from carrion collected by scavenging hymenopteran predators. Our focal system is the western yellowjacket (Vespula pensylvanica), a common scavenging predator in Hawaii and western North America. Prior to consumption, the physical properties of hymenopteran muscle tissue change in a quantifiable and deterministic manner post mortem and can be used to estimate the time and putative cause of death of diet items. Applying this method in laboratory and field situations resulted in the correct identification of prey and carrion in 49 out of 56 cases (88%). Although further investigation is needed to determine how post-mortem physiology of diet items changes in the guts of consumers, the approaches developed in this study can be used to distinguish predation from scavenging by central-place foragers (particularly arthropods). Such information will provide a more definitive characterization of species interactions and food webs.
Erin E Wilson; Christine V Young; David A Holway
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  213     ISSN:  1477-9145     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-07-19     Completed Date:  2010-10-19     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2640-6     Citation Subset:  IM    
Division of Biological Sciences, University of California, San Diego, 9500 Gilman Dr MC0116, La Jolla, CA 92093-0116, USA.
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MeSH Terms
Hydrogen-Ion Concentration
Hymenoptera / physiology*
Muscles / physiology*
Postmortem Changes
Predatory Behavior / physiology*
Regression Analysis
Stress, Physiological
Thorax / physiology*
Time Factors

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