title: Virtual forensic entomology: improving estimates of minimum post-mortem interval with 3D micro-computed tomography.
abstract: We demonstrate how micro-computed tomography (micro-CT) can be a powerful tool for describing internal and external morphological changes in Calliphora vicina (Diptera: Calliphoridae) during metamorphosis. Pupae were sampled during the 1st, 2nd, 3rd and 4th quarter of development after the onset of pupariation at 23 °C, and placed directly into 80% ethanol for preservation. In order to find the optimal contrast, four batches of pupae were treated differently: batch one was stained in 0.5M aqueous iodine for 1 day; two for 7 days; three was tagged with a radiopaque dye; four was left unstained (control). Pupae stained for 7d in iodine resulted in the best contrast micro-CT scans. The scans were of sufficiently high spatial resolution (17.2 μm) to visualise the internal morphology of developing pharate adults at all four ages. A combination of external and internal morphological characters was shown to have the potential to estimate the age of blowfly pupae with a higher degree of accuracy and precision than using external morphological characters alone. Age specific developmental characters are described. The technique could be used as a measure to estimate a minimum post-mortem interval in cases of suspicious death where pupae are the oldest stages of insect evidence collected.
authors.affiliation: Department of Entomology, Natural History Museum, Cromwell Rd, London SW7 5BD, UK. c.richards@nhm.ac.uk
authors.forename: Cameron S
authors.initials: CS
authors.lastname: Richards
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Simonsen
authors.forename: Richard L
authors.initials: RL
authors.lastname: Abel
authors.forename: Martin J R
authors.initials: MJ
authors.lastname: Hall
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Schwyn
authors.forename: Martina
authors.initials: M
authors.lastname: Wicklein
mesh_terms: D000818:Animals; D004175:Diptera / Q000254:growth & development*; D004772:Entomology; D005247:Feeding Behavior; D049429:Forensic Pathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D007455:Iodine; D007814:Larva / Q000254:growth & development; D008853:Microscopy; D010781:Photography; D011180:Postmortem Changes; D011679:Pupa / Q000254:growth & development; D011856:Radiographic Image Enhancement / Q000379:methods; D013194:Staining and Labeling; D013997:Time Factors; D055114:X-Ray Microtomography
chemical_list: D007455:Iodine