|Lehman, R - Michael|
|BROZEL, VOLKER - South Dakota State University|
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2014
Publication Date: 6/1/2014
Citation: Schmid, R.B., Lehman, R.M., Brozel, V.S., Lundgren, J.G. 2014. An indigenous gut bacterium, Enterococcus faecalis (Lactobacillales: Enterococcaceae), increases seed consumption by Harpalus pensylvanicus (Coleoptera: Carabidae). Florida Entomologist. 97(2):575-584.
Interpretive Summary: Harpalus pensylvanicus is a beneficial ground beetle commonly found in agroecosystems throughout the Midwest United States. Within the guts of the beetles a simple community of symbiotic microbes has been found containing the bacteria Enterococcus faecalis, which is thought to contribute to the digestion of the beetle’s diet. We ran a feeding assay consisting of four dietary treatments: antibiotic fed then E. faecalis fed, antibiotic fed then no E. faecalis, non-antibiotic fed then E. faecalis fed, non-antibiotic fed then no E. faecalis. Seed consumption of the beetles was measured. Results showed that beetles fed antibiotics and then E. faecalis consumed a greater weight of seeds, confirming the hypothesis that E. faecalis facilitates an increase in seed consumption by H. pensylvanicus. This research provides additional knowledge regarding benefits provided by the beetles potentially manifesting as a form of weed management for agricultural producers.
Technical Abstract: Harpalus pensylvanicus is a beneficial beetle contributing to insect control and seed predation in North American cropland. The bacterial endosymbiont Enterococcus faecalis is found in the intestinal tract of H. pensylvanicus and is thought to contribute to the digestion of the insect's seed diet. We assessed the ability of E. faecalis to increase seed consumption by H. pensylvanicus. This was tested through a laboratory feeding assay consisting of four dietary treatments, antibiotic +, E. faecalis +; antibiotic +, E. faecalis -; antibiotic -, E. faecalis +; and antibiotic -, E. faecalis -, in which seed consumption of the beetles was measured. Beetles administered antibiotics and then E. faecalis consumed a greater weight of seeds. These data provide further evidence that a gut microbiota dominated by E. faecalis facilitates seed consumption by H. pensylvanicus, possibly by contributing digestive enzymes to their host. Further research on the symbiotic relationship between E. faecalis and H. pensylvanicus and how to promote positive symbioses could increase the benefits of these beetles, which may be an additional advantage for agricultural producers as a form of weed management on top of other benefits provided by the beetles.