Colonization of stream macroinvertebrates by bacteria
McEwen, Heather; Leff, Laura G.
published: Mar 23, 2001
ArtNo. ESP141015101010, Price: 29.00 €
Aquatic invertebrates are exposed to bacteria in a variety of manners; in this study, colonization of invertebrates by three species of bacteria was examined. Rifampicin resistant strains of a common stream bacterium, Burkholderia cepacia, the coliform bacterium, Escherichia coli, and an insecticidal bacterium, Bacillus thuringiensis, were introduced into microcosms where they were given the opportunity to colonize aquatic invertebrates of several species. After incubation, the numbers of bacteria on the exterior surfaces of the invertebrates and in their digestive tract and feces were determined. In addition, two insect species were exposed to the bacteria as juveniles and then reared to adulthood. Overall, most bacterial species were able to effectively colonize the exterior surfaces of the invertebrates. In contrast, the foregut was not well colonized in all species of invertebrates (the bivalve Corbicula was particularly low) and the numbers in the hindgut were lower than in the foregut. Feces were colonized to varying degrees. The colonized invertebrates were able to function as vectors of the introduced bacteria, in that, they were able to disseminate the bacteria into new habitats. In general, there were few significant differences among invertebrate or bacterial species. The adult insects that had been provided introduced bacteria as larvae, typically retained these bacteria in their digestive tract; however, E. coli was not found in the gut of either species. In conclusion, almost all invertebrates were colonized by the different species of bacteria and even those bacteria which are not "native" or common in streams (E. coli and B. thuringiensis) were able to use the invertebrates as a habitat.