Carcasses at Fixed Locations Host a Higher Diversity of Necrophilous Beetles

Abstract

In contrast to other necromass, such as leaves, deadwood, or dung, the drivers of insect biodiversity on carcasses are still incompletely understood. For vertebrate scavengers, a richer community was shown for randomly placed carcasses, due to lower competition. Here we tested if scavenging beetles similarly show a higher diversity at randomly placed carcasses compared to easily manageable fixed places. We sampled 12,879 individuals and 92 species of scavenging beetles attracted to 17 randomly and 12 at fixed places exposed and decomposing carcasses of red deer, roe deer, and red foxes compared to control sites in a low range mountain forest. We used rarefaction-extrapolation curves along the Hill-series to weight diversity from rare to dominant species and indicator species analysis to identify differences between placement types, the decay stage, and carrion species. Beetle diversity decreased from fixed to random locations, becoming increasingly pronounced with weighting of dominant species. In addition, we found only two indicator species for exposure location type, both representative of fixed placement locations and both red listed species, namely Omosita depressa and Necrobia violacea. Furthermore, we identified three indicator species of Staphylinidae (Philonthus marginatus and Oxytelus laqueatus) and Scarabaeidae (Melinopterus prodromus) for larger carrion and one geotrupid species Anoplotrupes stercorosus for advanced decomposition stages. Our study shows that necrophilous insect diversity patterns on carcasses over decomposition follow different mechanisms than those of vertebrate scavengers with permanently established carrion islands as important habitats for a diverse and threatened insect fauna.

Factors influencing carrion communities are only partially consistent with those of deadwood necromass

“…A single carcass was placed on each of 21 plots and allowed to decompose for 30 days. For a more detailed schedule and description of the wildlife carcass exposition, see the Online Resource 1 (Table S1) and von Hoermann et al ( 2021 ). All 21 plots were arranged under semi-open canopies of mixed montane forests.…”

“…One trap was mounted adjacent to the carcass mouth, and the other adjacent to the anus, to provide two locations for sampling carrion insects attracted to the carcass (Dekeirsschieter et al 2011 ). For a more detailed pitfall trapping description, see von Hoermann et al ( 2021 ). To provide a consistent sample time period for each trapping event, pitfall trap lids were removed 48 h before content collection.…”

Linking bacteria, volatiles and insects on carrion: the role of temporal and spatial factors regulating inter-kingdom communication via volatiles

“…In carrion ecology, pitfall traps proved to be effective in capturing and mirroring a high diversity of the carrion-inhabiting community (e.g. [ 107 , 108 ]). In the near-natural forest of the Bavarian Forest National Park in Germany a high number of 97 necrophagous Diptera species retrieved from pitfall traps close to wildlife carcasses were confirmed by DNA metabarcoding (von Hoermann et al ., unpublished result).…”

Degradative succession of the insects in small rodents in subtropical systems

“…Decomposition is a continuous degradation process that releases CO2 and energy (Bornemissza, 1957;Higley & Huntington, 2009;Medeiros et al, 2015;Rezende et al, 2021) that starts at the death of the organism and end when the carcass is reduced to the skeleton (Probst et al, 2020;von Hoermann et al, 2021;Wolff et al, 2001). In addition, another important process is pedogenesis, which depends on animals that mix organic matter with mineral components in the soil (Moskowitz et al, 2015;Oliveira-Costa, 2013).…”

“…Therefore, insect colonization in carcasses decomposing with abiotic factors influence (e.g. temperature and moisture) and carcass conditions (e.g., completeness, toxicology, and pathology) may determine the decomposition rates in an ecosystem (Andrade-Herrera et al, 2020;Jales et al, 2020;Moretti et al, 2008;Von Hoermann et al, 2021).…”