Abstract
During decomposition, vertebrate carrion emits volatile organic compounds to which insects and other scavengers are attracted. We have previously found that the dung beetle, Anoplotrupes stercorosus, is the most common dung beetle found on vertebrate cadavers. Our aim in this study was to identify volatile key compounds emitted from carrion and used by A. stercorosus to locate this nutritive resource. By collecting cadaveric volatiles and performing electroantennographic detection, we tested which compounds A. stercorosus perceived in the post-bloating decomposition stage. Receptors in the antennae of A. stercorosus responded to 24 volatiles in odor bouquets from post-bloating decay. Subsequently, we produced a synthetic cadaver odor bouquet consisting of six compounds (benzaldehyde, DMTS, 3-octanone, 6-methyl-5-hepten-2-ol, nonanal, dodecane) perceived by the beetles and used various blends to attract A. stercorosus in German forests. In field assays, these beetles were attracted to a blend of DMTS, 3-octanone, and benzaldehyde. Generalist feeding behavior might lead to the super-dominant occurrence of A. stercorosus in temperate European forests and have a potentially large impact on the exploitation and rapid turnover of temporally limited resources such as vertebrate cadavers.
Highlights
In terrestrial ecosystems, vertebrate carrion and feces form unevenly distributed, ephemeral resource islands that are enriched with nitrogen, phosphorus, sulfur, and other vital elements, in contrast to the relatively nutrient-poor surroundings consisting of plant biomass [1,2]
By collecting over 10,000 individual forest dung beetles (A. stercorosus) in pitfall traps baited with stillborn piglet cadavers in German forests, we showed that this beetle species is lured to carrion, and, more importantly, that it is mainly attracted to the progressed decomposition stages (Figures S1 and S2)
Our aim was to characterize the compounds that occur in post-bloating cadaver odor bouquets and that can be perceived by the generalist dung beetle, A. stercorosus, by using gas chromatography coupled with electroantennographic detection (GC–EAD)
Summary
Vertebrate carrion and feces form unevenly distributed, ephemeral resource islands that are enriched with nitrogen, phosphorus, sulfur, and other vital elements, in contrast to the relatively nutrient-poor surroundings consisting of plant biomass [1,2]. These properties of dung and carrion, make them high-quality resources and hotspots of biological and chemical activity that microbes, insects, and other scavengers can utilize as their diet and for reproduction [2,3]. The post-bloating stage is associated with the strongest olfactory signature [12] This stage is characterized by the opening of the body caused by the overpressure of microbial gases and of orifices formed by the feeding processes of insects and vertebrate scavengers. The leakage of body fluids and the enhanced emission of VOCs increasingly attract further carrion-feeding insect taxa, such as burying beetles (Coleoptera: Silphidae) [10] and hide beetles (Coleoptera: Dermestidae) [18,19], until the advanced decay stage and even until the final stage of decomposition, when only dry material remains
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