Development of Thanatophilus micans (Fabricius 1794) (Coleoptera: Silphidae) at constant temperatures

Abstract

Thanatophilus micans is capable of finding corpses at least as quickly as most fly species and, as the most widespread species of the Silphidae in Africa, offers a useful model for estimating post-mortem interval. Larvae were reared at ten constant temperatures from 15 degrees C to 35 degrees C and their length measured at 4, 8, or 12-h intervals depending on their instar. Length generally increased with increased rearing temperature, but decreased at extremely high temperatures. Note was made of the age at which individuals progressed past developmental milestones. Development took longer at lower temperatures. These results are presented as a combined isomegalen and isomorphen diagram. Developmental constants were generated for each milestone using major axis regression. Developmental threshold values did not differ significantly between milestones. Development took longer than in blow flies, but was faster than in Dermestidae. The three models presented here, therefore, cover an important time frame in estimating minimum PMI once fly larvae have matured to the point of leaving a corpse, and, therefore, provide a tool that was not previously available to forensic entomologists.

Carrion Beetles Visiting Pig Carcasses during Early Spring in Urban, Forest and Agricultural Biotopes of Western Europe

“…Many forensic entomological studies have been conducted on pig carcasses as surrogate human models for physiological, ethical and economical reasons (Rodriguez and Bass 1983; Catts and Goff 1992; Anderson and VanLaerhoven 1996; Grassberger and Frank 2004; Hart and Whitaker 2005), but few were conducted in Europe with pig carcasses (Grassberger and Frank 2004; Garcia-Rojo 2004; Wyss and Cherix 2006; Matuszewski et al 2008). Many published reports are focused on Diptera pattern colonization and very few looked at Coleoptera succession (Kocarek 2003; Matuszewski et al 2008; Midgley and Villet 2009, Midgley et al 2010). However, the use of beetles in forensic entomology can be relevant (Kulshrestha and Satpathy 2001; Midgley et al 2010).…”

How promptly do blowflies colonise fresh carcasses? A study comparing indoor with outdoor locations

“…By calculating the age of the most developed insect larvae, a minimum time since death can be indicated [6]. Several studies deal with the developmental time of larvae of several fly and beetle species using carcasses as breeding sites [10,1,2,21,13] and with different ways of calculating larval age [20,15]. Corpses in houses or apartments are frequently found in late stages of decay infested by larvae of Calliphoridae, Phoridae, Muscidae or Sarcophagidae.…”

Effect of the killing method on post-mortem change in length of larvae of Thanatophilus micans (Fabricius 1794) (Coleoptera: Silphidae) stored in 70% ethanol

“…Small specimens could be young or stunted by competition or low temperatures [9,13]), but length measurements cannot take this into account [6]. Even when these effects are absent, there is natural variation in body length at any given age [5,9], resulting in sampling error in length measurement, and larvae of the same species moult at different lengths, meaning that reaching a given length does not trigger moulting and is therefore not a direct surrogate for age. However, with dead samples, it is perhaps the best indicator available.…”

“…Thanatophilus micans adults have been observed on animal carcasses within 24 h of death (personal observation) and larvae within 4 days, which coincides with the egg development period [9]. The total development time in T. micans is longer than in most flies, which make T. micans larvae an important forensic indicator once fly larvae are no longer present on a corpse.…”