title: Differences among antimicrobial properties of carrion beetle secretions reflect phylogeny and ecology.
abstract: Carrion beetles (Coleoptera: Silphidae) consist of two subfamilies in North America. Members of the Silphinae arrive at carcasses during the mid-stage of decay and their larvae feed on developing maggots, while members of the Nicrophorinae bury and tend carcasses upon which their developing larvae feed. The Nicrophorinae maintain the condition of the carcass by applying oral and anal secretions that reduce carcass decay apparently through bacterial inhibition, although quantification has not been made. We hypothesized that enzymes in the oral and anal secretions of the subfamily Nicrophorinae would inhibit bacterial growth, while secretions from the subfamily Silphinae would not. The secretions were assayed for inhibitory effects with a Microtox Analyzer that monitors the decrease in bioluminescence from the bacterium Vibrio fischerii. We found a significant difference of bioluminescence in the control compared to secretions of 8 out of 10 tested Nicrophorinae (with oral secretions being most active), while only anal secretions from Necrodes surinimensis of the Siphinae significantly reduced bacterial survival. These data follow the known phylogenic relationship in which Necrodes is the closest genus to the Nicrophorinae. The two species of Nicrophorinae, which did not show significant reductions in bacterial growth, differ ecologically from the others. Thus, the presence of antimicrobial compounds in most Nicrophorinae secretions, but not in most other Silphinae, represents an adaptation to preserve the buried carcass.
authors.affiliation: Department of Biology, University of Nebraska at Kearney, 905 W. 25th Street, Kearney, Nebraska 68849, USA. hobackww@unk.edu
authors.forename: W Wyatt
authors.initials: WW
authors.lastname: Hoback
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Bishop
authors.forename: Jeremy
authors.initials: J
authors.lastname: Kroemer
authors.forename: Joanne
authors.initials: J
authors.lastname: Scalzitti
authors.forename: Julie J
authors.initials: JJ
authors.lastname: Shaffer
mesh_terms: D000695:Anal Sacs / Q000737:chemistry / Q000502:physiology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D001409:Bacillus cereus / Q000254:growth & development; D001517:Coleoptera / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004463:Ecology; D005247:Feeding Behavior; D007814:Larva / Q000502:physiology; D009055:Mouth / Q000737:chemistry / Q000502:physiology; D010802:Phylogeny; D014733:Vibrio / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents