Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 22, 2006
Publication Date: April 1, 2007
Citation: Lundgren, J.G., Lehman, R.M., Chee Sanford, J. 2007. Bacterial communities within the digestive tracts of ground beetles (Coleoptera: Carabidae). Annals of the Entomological Society of America. 100:275-282. Interpretive Summary: Ground beetles are important biological control agents in agricultural systems, consuming both insect pests and weed seeds. Previously, we fed two seed-feeding species antibiotics, and observed that seed consumption was reduced. We hypothesize that this was due to potential bacterial contribution to digestion, which is commonly found in other insects. With this in mind, we describe the bacterial communities of two abundant and granivorous ground beetles.
Technical Abstract: We identified the bacterial communities within the alimentary tracts of two granivorous ground beetles. We conducted feeding studies on Harpalus pensylvanicus using diet-administered antibiotics to “cure” beetles of microorganisms within their digestive tracts. T-RFLP analyses of bacterial rDNA extracted from the guts of field collected individuals of H. pensylvanicus and Anisodactylus sanctaecrucis revealed that gut associated bacterial communities were of low diversity. Individuals from the same beetle species possessed similar bacterial community profiles, but the two species exhibited unique profiles. Bacterial 16S rDNA clone libraries constructed for the two beetle species showed that H. pensylvanicus had a more diverse community (6 operational taxonomic units (OTU)) compared to A. sanctaecrucis (3 OTU). Only one OTU, closely related to Hafnia alvei, was common between the two beetle species. Cloned partial 16S rDNA sequences for each OTU were most closely matched to the following cultivated bacteria: Serratia sp., Burkholderia fungorum, and Hafnia alvei and Phenylbacterium sp., Caedibacter sp., Spiroplasma sp., Enterobacter strain B-14, and Weissella viridescens, representing the divisions Alpha-, Beta- and Gamma-proteobacteria, Mollicutes and Bacilli. Some, but not all of these organisms have been previously associated with insects. The identification of bacteria uniquely and consistently associated with these ground beetles provides the basis for further investigation of species-specific functional roles.