PMI estimation

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Insect succession and carrion decomposition in
selected forests of Central Europe.
Part 2: Composition and residency patterns of
carrion fauna
Szymon Matuszewski,Daria Bajerlein,Szymon Konwerski,Krzysztof Szpila
Presenter –
Divyanshu Singh
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2. Introduction
• PMI ??
• After death body undergoes many changes
• Forensic entomology - insect activity on the corpse
• Analysis of composition of carrion fauna and selected features of residency
in carrion in adults and larvae of particular taxa.
• Implications for
 Succession-based post-mortem interval (PMI) estimation
 Determination of the carcass movement
 Determination of the season of death
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3. The Approach
•Determine the forensic usefulness of carrion insects by
 recognition of reoccurring taxa
 quantify feature of residency
 relationship between a given taxon presence
and a particular state of the carcass
• Factors considered:
• Seasons - spring, summer and autumn
• Forest type - pine-oak forest, hornbeam-oak forest and alder forest
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4. Data Analysis, Results and Discussion
1. The composition of carrion fauna
2. The residency patterns of carrion fauna
3. The relationship between appearance time of carrion fauna and onsets of
decomposition processes
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5. The composition of carrion fauna
• Two-way analysis of variance (ANOVA)
Evaluate the significance of season and forest effect on the number of
minimally abundant taxa.
•The composition of adult and larva of Diptera and
Coleoptera
Number of taxa minimally abundant in adult stage
Number of taxa minimally abundant in larval stage
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6. Observation
 Seasonal differences seen
 Differences in pattern results from
• the seasonality of carrion taxa
• seasonal differences in decomposition
 Not much differences seen in different forest types
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7. The residency patterns of carrion fauna
• Comparison of taxa
• Determination of
 Length of the presence period
 Number of breaks in the presence period
 Length of the longest unbroken period
• To calculate relative length of the presence period (RLPP)
RLPP = LPP * 100% (LPP-length of presence period
LSI LSI-length of sampling interval.)
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8. Observation
 Length of the presence period in Diptera and Coleoptera
• Closer the relation between a taxon and carrion, shorter is
its presence period.
• Presence period of carrion-breeders was seen to be 46%
and carrion feeders 66%.
 Breaks in the presence period in Diptera and Coleoptera
• Residency was broken in case of adult carrion taxa and unbroken
in case of larval carrion taxa .
C – a reoccurring taxon with breaks clumped, b – a break in the presence period, lup – the longest
unbroken period, pp – the presence period.
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9. The relationship between appearance time of
carrion fauna and onsets of decomposition
processes
 Correlational analysis
To evaluate the relationship between the appearance time of a taxon
and different decompositional processes
 The Pearson product–moment correlation coefficient
used
• Outliers in scatterplot omitted
• Results of significant taxa presented
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10. Observation
 Key Variable affecting decomposition - Ambient temperature
 Ambient temperature closely related to
• Onset of bloating
• Appearance time of taxon
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11. Implications for forensic entomology
 Estimation of PMI
• Presence or absence of taxa on the carcass
 Determination of the carcass movement
• Differences between forest and open habitats suggest the
composition of insect fauna
 Determination of the season of death
• 2 season or 1 season taxa
• More experimentation needed
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12. Take Home Message
 For the composition of carrion fauna, large differences between seasons, but
no important differences between forest types.
 Residency of adults was broken, residency of larvae was unbroken.
 In adults, two distinct residency patterns observed;
• with breaks clumped in the final part of the presence period
• with breaks evenly distributed inside the presence period
 Almost in all taxa, the time of appearance showed the closest, significant,
positive and strong relationship to the onset of bloating.
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13. 13
References
1. http://entomology.wsu.edu/courses/coursefiles/ENTOM101/ENT101%20Fall200
6/ent%20101%20carrion%202006.pdf
3. S. Matuszewski, D. Bajerlein, S. Konwerski, K. Szpila, Insect succession and
carrion decomposition in selected forests of Central Europe. Part 1: Pattern and
rate of decomposition, Forensic Sci. Int. (2009),
doi:10.1016/j.forsciint.2009.10.016.
5. J.D. Wells, L.R. LaMotte, Estimating the postmortem interval, in: J.H. Byrd, J.L.
Castner (Eds.), Forensic Entomology. The Utility of Arthropods in Legal
Investigations,CRC Press, Boca Raton, 2001, pp. 263–285.
6. www.google.co.in
8. www.wikipedia.org
Castner (Eds.), Forensic Entomology. The Utility of Arthropods in Legal
Investigations,CRC Press, Boca Raton, 2001, pp. 263–285.
11. http://www.benecke.com/pdf-files/elderlyneglect.pdf
13. http://en.wikipedia.org/wiki/Post-mortem_interval
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14. Thank you for your attention!
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