Microbial volatiles and succession of beetles on small carrion

• Published in: Ecological entomology 2022-10, Vol.47 (5), p.758-769
• Main Authors: Trumbo, Stephen T., Newton, Alfred F.
• Format: Article
• Language: English
• Subjects: Beetles; Carcasses; Carrion; chemical ecology; Coleoptera; Decay; Decomposition; Dimethyl sulfide; Ecological succession; forensic entomology; Forensic science; Insects; Microbial activity; Microorganisms; Mixtures; Seasonal variations; Silphidae; Staphylinidae; Sulfides; Sulfur; Thiocyanates; Traps; Volatile compounds; Volatiles
• ISSN: 0307-6946; 1365-2311
• DOI: 10.1111/een.13160

Ecological succession is understood in general terms (facilitation, tolerance, inhibition) even though the system‐specific mechanisms often remain elusive. The succession of insects on carrion is an important model because of its applications to ecosystem function and forensic science. It recently has been hypothesized that changing volatile cues produced by microbes drive succession on carrion. The authors investigated how two blends of sulphur volatiles attracted beetles that typically colonise during the fresh or active decay stages of carrion decomposition. Most beetles attracted to a fresh carcass or to a fresh carcass + dimethyl sulphide/methyl thiocyanate (DMS/MeSCN) blend were burying beetles that breed on small carcasses (95% Nicrophorus spp. other than Ni. pustulatus), with more beetles attracted to the chemically‐supplemented traps. Beetles attracted to carcasses in active decay (Ni. pustulatus, silphines, staphylinids) were also attracted to a fresh carcass + dimethyl disulphide/dimethyl trisulphide (DMDS/DMTS) blend, evidence that DMDS and DMTS are important cues for beetles during the middle stages of decomposition. The Fresh + DMDS/DMTS traps, however, were not a perfect mimic of a carcass in active decay. There were seasonal differences in attractiveness that the authors speculate are due to beetles responding to cues from carcasses used for feeding versus breeding. A second experiment demonstrated a synergy between DMDS and DMTS in attracting Ni. pustulatus and Euspilotus assimilis. The results support the hypotheses that changes in microbial communities and their volatiles during decomposition drive the succession of carrion‐frequenting insects and that blends of volatiles are necessary for some species to identify the targeted stage of decomposition. The cues that attract necrophilous beetles to different stages of carrion succession were investigated using baits supplemented with microbially‐derived volatiles. Fresh carcasses supplemented with methyl thiocyanate attracted carrion‐breeding Nicrophorus beetles; fresh carcasses supplemented with dimethyl disulphide and dimethyl trisulphide attracted beetles associated with active decay. It is hypothesized that changing microbial communities and their volatiles during carcass decomposition drive the well‐known successional pattern of insects.