Submitted to: BMC Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2006
Publication Date: 5/15/2006
Citation: Evans, J.D., Armstrong, T.N. 2006. Antagonistic interactions between honey bee bacterial symbionts and implications for disease. BMC Ecology. 6:4. Interpretive Summary: Honey bees are often exposed to pests and pathogens, generating great expenses for beekeepers and affecting the abilities of bees to provide hive products and perform important pollination roles. The widespread brood disease American Foulbrood (AFB) is caused by the bacterium Paenibacillus larvae. Here we describe a novel search for means to control this pathogen. We survey colonies for additional resident bacteria species that directly inhibit the AFB bacterium. We report a large set of such bacteria and discuss how they might be involved in natural disease resistance. These beneficial bacteria also might be introduced to colonies as a means of controlling disease, providing a new tool for beekeepers in controlling this bacterium and reducing reliance on conventional antibiotics.
Technical Abstract: Insects harbor diverse bacterial symbionts, many of which have strong effects on insect survival and reproduction. Facultatively symbiotic bacteria can affect insect nutrition, immuno-competence, and susceptibility to disease agents. Honey bees and other social insects maintain a diverse microbial biome within which inhibitory and mutualistic interactions are expected. Here we isolate, culture, and describe by 16srRNA and protein-coding gene sequences 61 bacterial isolates from honey bee larvae, reflecting a total of 43 distinct bacterial taxa. We culture these bacteria alongside the primary larval pathogen of honey bees, Paenibacillus larvae, and show that many of these isolates severely inhibit the growth of this pathogen. Accordingly, symbiotic bacteria including those described here are plausible natural antagonists toward this widespread pathogen. The results suggest a tradeoff in social insect colonies between the maintenance of potentially beneficial bacterial symbionts and deterrence at the individual and colony level of pathogenic species. They also provide a novel mechanism for recently described social components behind disease resistance in insect colonies, and point toward a potential control strategy for an important bee disease.