Temperature-dependent appearance of forensically useful beetles on carcasses

Estimating the pre-appearance interval (PAI) of carrion insects from temperature is a new and promising improvement of entomological methods for post-mortem interval estimation. In order to use this approach in casework, a taxon should demonstrate a close relationship between PAI and temperature. In this article we test this relationship in selected species of beetles, namely Thanatophilus sinuatus Fabr., T. rugosus L., Necrodes littoralis L. (Silphidae), Necrobia rufipes De Geer, N. violacea L. (Cleridae), Dermestes frischii Kug. (Dermestidae), Creophilus maxillosus L., Philonthus politus L., Ontholestes murinus L. (Staphylinidae), Saprinus semistriatus Scriba, S. planiusculus Motch. and Margarinotus brunneus Fabr. (Histeridae). Data were collected from 30 pig carcasses decomposing under different temperature conditions in open and forest habitats of Western Poland. Beetles were sampled with pitfall traps and with manual and soil sampling. The on-site temperature of the ground level was recorded. The relationship was tested separately in adult and larval stages. All species, except for D. frischii, revealed significant relationship between PAI and temperature. In all cases PAI was found to decrease exponentially with an increase in temperature. Moreover, above some temperature it was nearly constant. The relationship was strong in the case of adult and larval N. littoralis, adult N. rufipes, adult and larval C. maxillosus, adult P. politus, S. semistriatus and S. planiusculus. The relationship of moderate strength was found for adult and larval T. sinuatus, adult N. violacea and adult M. brunneus. In the case of adult T. rugosus and O. murinus the relationship was weak. Current results demonstrate that there are solid premises for estimating PAI from temperature in T. sinuatus, N. littoralis, N. rufipes, N. violacea, C. maxillosus, P. politus, S. semistriatus, S. planiusculus and M. brunneus. Implications for forensic entomology are discussed.