title: Hydrocarbon profiles throughout adult Calliphoridae aging: A promising tool for forensic entomology.
abstract: Blow flies (Diptera: Calliphoridae) are typically the first insects to arrive at human remains and carrion. Predictable succession patterns and known larval development of necrophagous insects on vertebrate remains can assist a forensic entomologist with estimates of a minimum post-mortem interval (PMImin) range. However, adult blow flies are infrequently used to estimate the PMImin, but rather are used for a confirmation of larval species identification. Cuticular hydrocarbons have demonstrated potential for estimating adult blow fly age, as hydrocarbons are present throughout blow fly development, from egg to adult, and are stable structures. The goal of this study was to identify hydrocarbon profiles associated with the adults of a North American native blow fly species, Cochliomyia macellaria (Fabricius) and a North American invasive species, Chrysomya rufifacies (Macquart). Flies were reared at a constant temperature (25°C), a photoperiod of 14:10 (L:D) (h), and were provided water, sugar and powdered milk ad libitum. Ten adult females from each species were collected at day 1, 5, 10, 20, and 30 post-emergence. Hydrocarbon compounds were extracted and then identified using gas chromatography-mass spectrometry (GC-MS) analysis. A total of 37 and 35 compounds were detected from C. macellaria and Ch. rufifacies, respectively. There were 24 and 23 n-alkene and methyl-branched alkane hydrocarbons from C. macellaria and Ch. rufifacies, respectively (10 compounds were shared between species), used for statistical analysis. Non-metric multidimensional scaling analysis and permutational multivariate analysis of variance were used to analyze the hydrocarbon profiles with significant differences (P<0.001) detected among post-emergence age cohorts for each species, and unique hydrocarbon profiles detected as each adult blow fly species aged. This work provides empirical data that serve as a foundation for future research into improving PMImin estimates made by forensic practitioners and potentially increase the use of adult insects during death investigations.
authors.affiliation: Department of Entomology, 243 Natural Science, Michigan State University, East Lansing, MI 48824, USA. Electronic address: pechalje@msu.edu.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Pechal
authors.affiliation: School of Physical and Geographical Sciences, Keele University, ST5 5BG Staffordshire, UK. Electronic address: hanamoore@yahoo.co.uk.
authors.forename: Hannah
authors.initials: H
authors.lastname: Moore
authors.affiliation: School of Physical and Geographical Sciences, Keele University, ST5 5BG Staffordshire, UK. Electronic address: f.drijfhout@keele.ac.uk.
authors.forename: Falko
authors.initials: F
authors.lastname: Drijfhout
authors.affiliation: Department of Entomology and Department of Osteopathic Medical Specialties, 243 Natural Science, Michigan State University, East Lansing, MI 48824, USA. Electronic address: benbow@msu.edu.
authors.forename: M Eric
authors.initials: ME
authors.lastname: Benbow
mesh_terms: D000375:Aging; D000818:Animals; D004175:Diptera / Q000737:chemistry* / Q000254:growth & development*; D004772:Entomology; D005247:Feeding Behavior; D044707:Forensic Sciences; D006838:Hydrocarbons / Q000032:analysis*; D011180:Postmortem Changes
chemical_list: D006838:Hydrocarbons
keywords: Adult aging; Calliphoridae; Forensic entomology; Hydrocarbons