An Experimental Investigation Into the Colonization of Concealed Cadavers by Necrophagous Blowflies

Abstract

We used seven baited boxes with different combinations of access holes and odor diffusion surfaces to study the arrival of necrophagous flies. During laboratory experiments, 30 gravid Lucilia sericata females were kept in a chamber with one of the boxes. The box with the largest odor diffusion surface (99 cm2) combined with the lowest accessibility (one 1 cm2 entrance hole) was entered least (5 ± 3.7 flies per run). In contrast, the most frequently entered box (one 9 cm2 entrance hole with no additional odor diffusion surface) caught a mean of 24.6 ± 3.4 flies per run. These results indicate that 1) L. sericata entered nearly inaccessible places and 2) both odor diffusion and accessibility impacted the number of flies caught. During field experiments, the seven boxes were placed together outdoors. The box with the most entrances (ten 9-cm2 holes) caught the most flies (55.6–99.4% of the total). Only a few flies entered the other boxes. Access to the less accessible boxes (poor odor diffusion and small entrances) was also delayed. The major conclusions of the field experiments are that 1) boxes with low accessibility took longer to be accessed; 2) larger odor diffusion surfaces were more attractive to flies; and 3) flies accessed boxes more readily through larger holes than through an equivalent surface area made up of smaller holes. With these conclusions in mind, attempts to quantify the preappearance interval or to interpret the number of flies observed in indoor forensic entomology cases should be approached with caution.

Oviposition preferences and antennal size in carrion flies

“…Traps baited with decaying marine fish flesh captured the most individuals, whereas traps baited with decaying pig liver typically attracted the least. This largely consistent pattern of relative preferences for different sources of odour has not been widely reported for carrion flies in natural populations, perhaps reflecting the more typical forensic entomological research focus on how oviposition behaviour is influenced by variation in the characteristics of the same carcass species (Archer & Elgar, 2003a,b; Gião & Godoy, 2007; Gunn & Bird, 2011; Yang & Shiao, 2012; Charabidze et al, 2015; Gunn, 2016; Martin & Verheggen, 2018; but see Bunchu et al, 2008). We also found that individuals of L. sericata and an unidentified platystomatid collected from the traps baited with pig liver tended to have longer antennae than those collected from the other traps.…”

“…For example, the oviposition behaviour of Lucilia sericata (Meigen) (Diptera: Calliphoridae) is influenced by two semiochemicals: individuals are initially attracted to sulphur‐rich volatiles, originating from bacterial composition products, and then commence ovipositing in response to ammonia‐rich compounds and carbon dioxide (Ashworth & Wall, 1994). Trap sampling and behavioural assays reveal that the oviposition choices of carrion flies are influenced by the age and body part of the corpse, presence of larval competitors and predators, and location of the corpse on the substrate (Archer & Elgar, 2003a,b; Gião & Godoy, 2007; Gunn & Bird, 2011; Yang & Shiao, 2012; Charabidze et al, 2015; Gunn, 2016; Martin & Verheggen, 2018).…”

The Effect of Cement and wrapping on the Decomposition rate of the Rabbit Carcasses

“…Even though time taken were not signi icantly different for ground exposed and wrapped control carcasses to reach irst sign of skeletonised stage, it was signi icant under freshwater as wrapping factor delay the decomposition by 2 times. It was explained by Charabidze D et al [38], carcasses with low accessibility took longer to be accessed by the necrophagous lies.…”

Use of necrophagous insects as evidence of cadaver relocation: myth or reality?

“…The question of the inside/outside location of a cadaver is a key point in many forensic investigations ( Frost et al, 2010 ). The location of a cadaver affects its colonization time (the pre-appearance interval, i.e., the time before insects reach the cadaver) and thus the post-mortem interval estimation ( Pohjoismaki et al, 2010 ; Reibe & Madea, 2010 ; Charabidze, Hedouin & Gosset, 2015 ). Furthermore, access to the cadaver by necrophagous insects greatly affects its decomposition ( MacLeod & Donnelly, 1962 ; Campobasso, Di Vella & Introna, 2001 ).…”