Is Resource Change a Useful Predictor of Carrion Insect Succession on Pigs and Humans?

Abstract

Carrion is a dynamic and nutrient-rich resource that attracts numerous insect species that undergo succession due to the rapid change in the carrion resource. Despite this process being well-understood, few studies have examined resource change as a driver of carrion insect succession, and instead have focused on the effects of time per se, or on coarse, qualitative measures such as decay stage. Here we report on three field succession experiments using pig carcasses and human cadavers encompassing two winters and one summer. We quantified the effects of resource change (measured as total body score, TBS), carrion type, initial carrion mass, ambient temperature, and season on insect species richness and community composition. We found that all variables had an effect on different taxonomic or trophic components of the insect community composition, with the exception of initial carrion mass which had no effect. We found significant positive effects of TBS on beetle species richness and composition, while fly species richness was not significantly affected by TBS, but was by ambient temperature. TBS had a significant positive effect on all trophic groups, while ambient temperature also had a significant positive effect on the necrophages and predator/parasitoids. Our study indicates that resource change, as indicated by TBS, is an important driver of carrion insect species turnover and succession on carrion, and that TBS can provide information about insect ecological patterns on carrion that other temporal measures of change cannot.

Insect abundance patterns on vertebrate remains reveal carrion resource quality variation

“…We used six human cadavers and five pig carcasses (see Dawson et al 2021b for human and pig details). Our sample size is consistent with other studies using human cadavers, since sourcing cadavers in high numbers is logistically challenging (Knobel et al 2019) Pigs were killed by the abattoir using a captive head bolt and were transported to AFTER within one hour of death.…”

“…acknowledgement of the rapid change in carrion quality underpinning the very well-documented patterns in succession (Michaud et al 2015;Evans et al 2020;Dawson et al 2021b).…”

“…The quality of carrion as a resource is difficult to define due to its dynamic and continuously changing state, which includes changes in quality (nutritional output), digestibility, and quantity (biomass) (Barton et al 2019;Benbow et al 2019). The objective quality of carrion varies greatly from the onset of fresh decay through to dried remains, with optimal nutritional quality differing among species and depending on their adaptations and timing of colonising the remains (Dawson et al 2021b). For some arthropods, such as primary colonising flies that require carrion in this condition for their larvae to feed on, fresh carrion is preferred as a high-quality resource (Evans et al 2020).…”

“…Recent research on carrion insects has demonstrated that changes in carrion resource, as indicated by total body score (TBS), is an important factor driving insect species richness and community turnover (Dawson et al 2021b). Total body score is an ideal measure of resource change as it is a measure of decomposition and incorporates both the physical and chemical changes occurring on carrion.…”

Blowflies Reared in Laboratory Conditions from Maggots Collected on Rat (Rattus norvegicus Berkenhout, 1769, Var Wistar) Carrions in Yaoundé (Cameroon, Central Africa)

“…[50][51][52][53] used carcasses of pigs as trapping substrates. [54,55,56,12,57] utilized multiple trapping baits while [58,59] employed fish when [60,61] used chicken liver as bait. This multitude of biological models of trapping substrates gives new opportunities to authors to enrich their database on forensic entomology.…”