Commonly Used Intercarcass Distances Appear to Be Sufficient to Ensure Independence of Carrion Insect Succession Pattern

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Forensic entomology field researchers have typically placed experimental carcasses ≤50 m apart. Direct observations indicate that this intercarcass distance sufficiently prevents cross contamination by crawling larvae, but seems insufficient to prevent highly mobile adult insects from detecting or visiting more than one carcass. It would be valuable if minimum intercarcass distance ensured independence of replicates, because this is an assumption of common statistical analyses. For 32 domestic pig carcasses exposed during two consecutive summers (range of intercarcass distance 30 to >300 m), possible relationships between: 1) average distance to another carcass and aspects of the succession patterns of forensically important species and 2) intercarcass distance and community similarity indices were estimated with regression analyses. In addition, minimum intercarcass distance was investigated through semivariogram analyses of aspects of the succession interval as well as community similarity indices. Pairwise similarity of time to first occurrence was the only variable that displayed a consistent, in this case negative, relationship to intercarcass distance, although not statistically significant for any single analysis. Semivariogram analysis suggested that under the conditions used for our experiment commonly used intercarcass distances are satisfactory to ensure independence of carcasses.