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Gene Expression During Blow Fly Development: Improving the Precision of Age Estimates in Forensic Entomology

Authors

  • Aaron M. Tarone Ph.D.,

    1. Department of Zoology, Natural Science Building, Michigan State University, East Lansing, MI 48824.
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    • Present address: Department of Entomology, 2475 Texas A&M University, College Station, TX.

  • David R. Foran Ph.D.

    1. Department of Zoology, Natural Science Building, Michigan State University, East Lansing, MI 48824.
    2. Forensic Science Program, School of Criminal Justice 560 Baker Hall, Michigan State University, East Lansing, MI 48824.
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  • A portion of this work was presented at the 59th Annual Meeting of the American Academy of Forensic Scientists, February 19–24, 2007, in San Antonio, TX.

  • Supported by Grant Number 2004-DN-BX-K005, awarded by the National Institute of Justice, Office of Justice Programs, US Department of Justice.

Additional information and reprint requests:
David R. Foran, Ph.D.
School of Criminal Justice and Department of Zoology
560 Baker Hall
Michigan State University
East Lansing, MI 48824
E-mail: foran@msu.edu

Abstract

Abstract:  Forensic entomologists use size and developmental stage to estimate blow fly age, and from those, a postmortem interval. Since such estimates are generally accurate but often lack precision, particularly in the older developmental stages, alternative aging methods would be advantageous. Presented here is a means of incorporating developmentally regulated gene expression levels into traditional stage and size data, with a goal of more precisely estimating developmental age of immature Lucilia sericata. Generalized additive models of development showed improved statistical support compared to models that did not include gene expression data, resulting in an increase in estimate precision, especially for postfeeding third instars and pupae. The models were then used to make blind estimates of development for 86 immature L. sericata raised on rat carcasses. Overall, inclusion of gene expression data resulted in increased precision in aging blow flies.

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