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Seasonal Effects on Carrion Decomposition and Insect Colonization

Award Information

Award #
2017-R2-CX-0004
Location
Awardee County
Yolo
Congressional District
Status
Open
Funding First Awarded
2017
Total funding (to date)
$147,229

Description of original award (Fiscal Year 2017, $50,000)

Insect colonization of carrion is a continuous, overlapping series of trophic interactions and ecological successions. Insect scavengers, predators, and parasitoids appear to follow predictable colonization patterns governed by a multitude of biotic and abiotic factors, including species competition, decomposition state, weather, and temperature.

Due to its predictable nature, the principles of successional ecology can be applied by forensic entomologists to estimate the period of infestation in decedents. This estimated period of time can then serve as a proxy for time elapsed since death in criminal investigations. Despite its strong ecological foundations, succession based forensic entomology is still a developing field of research. This may negatively affect its reliability for use by expert witnesses.

For successional work, statistical confidence has been hampered by factors such as pseudoreplication and observational-based emphases. These weaknesses can at least partially be attributed to the problematic length of multi-year seasonal studies. The scope of this work fills the need for a multi-season and year successional analysis.

Accordingly, the researchers placed five pig carrion in the University of California, Davis Riparia Reserve each season for two consecutive years. For each carrion, the researchers sampled insects present and recorded state of decomposition over the course of a full year. Additionally, the researchers recorded both historical and concurrent NOAA weather data from the nearby University of California, Davis Experimental Farm. The intent is to analyze annual and seasonal variation of insect succession, diversity, decomposition, and weather through multiple regression analyses.

Finally, the researcher will attempt to coalesce these factors to a form a predictive model of insect succession in decedents. Ultimately, we seek to strengthen the potential utility of successional ecology for expert testimony by forensic entomologists.

ca/ncf

Estimating the time of death of a cadaver based on the types of insects present in the remains and their stage of development is an established forensic practice. The applicant proposes to strengthen the statistical confidence underlying this practice through an analysis of the progression of insects present on pig carcasses for two consecutive years. (Pigs are widely used as analogs for humans and human cadavers in science.) Based on the data collected, the applicant further proposes to develop a predictive model of insect succession in cadavers.

"Note: This project contains a research and/or development component, as defined in applicable law," and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14). nca/ncf

Insect colonization of carrion is a continuous, overlapping series of trophic interactions and ecological successions. Insect scavengers, predators, and parasitoids appear to follow predictable colonization patterns governed by a multitude of biotic and abiotic factors, including species competition, decomposition state, weather, and temperature. Due to its predictable nature, the principles of successional ecology can be applied by forensic entomologists to estimate the period of infestation in decedents. This estimated period of time can then serve as a proxy for time elapsed since death in criminal investigations. Despite its strong ecological foundations, succession based forensic entomology is still a developing field of research. This may negatively affect its reliability for use by expert witnesses, particularly in light of Daubert vs. Merrell Dow Pharmaceuticals. For successional work, statistical confidence has been hampered by factors such as pseudoreplication and observational-based emphases. These weaknesses can at least partially be attributed to the problematic length of multi-year seasonal studies. The scope of this work fills the need for a multi-season and year successional analysis. Accordingly, we placed five pig carrion in the University of California, Davis Riparia Reserve each season for two consecutive years. For each carrion, we sampled insects present and recorded state of decomposition over the course of a full year. Additionally, we recorded both historical and concurrent NOAA weather data from the nearby University of California, Davis Experimental Farm. We intend to analyze annual and seasonal variation of insect succession, diversity, decomposition, and weather through multiple regression analyses. Finally, we shall attempt to coalesce these factors to a form a predictive model of insect succession in decedents. Ultimately, we seek to strengthen the potential utility of successional ecology for expert testimony by forensic entomologists.

"Note: This project contains a research and/or development component, as defined in applicable law," and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14). NCA/NCF

Date Created: September 29, 2017