Bacteria involved in the health of honey bee (Apis mellifera) colonies
Date
2014
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Publisher
University of Delaware
Abstract
In recent years there has been a dramatic worldwide increase in the loss of honey bee (Apis mellifera ) colonies (1). This decline has received much attention due to the important ecosystem service they provide; pollination. The bacterial flora in colonies has important roles including protecting honey bees from pathogens by preventing their colonization and producing antimicrobial compounds as well as aiding in the conversion of pollen to bee bread (2, 3, 4). These findings suggest that the bacterial flora in bee bread is important for honey bee colony health. Antibiotics used in honey bee colonies and on plants pollinated by honey bees include Oxytetracycline HCl, Streptomycin, Tylosin Tartrate, and Fumagillin-B. However, the mode of action of these antibiotics is not specific towards pathogens; therefore commensal organisms can also be affected. The goal of this research was to determine if the bacterial flora of bee bread in honey bee colonies reflects the health of the colony. Bee bread was sampled from 15 colonies in the University of Delaware Research Apiary from May to October 2013. Colony characteristics including total number of bees, total number of brood, brood pattern, and the amounts of honey, pollen, and nectar were also determined. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) were used as a bacterial fingerprinting technique to get a profile of all the culturable and nonculturable bacteria present. Culturable bacteria were isolated from the bee bread samples and identified using fatty acid methyl ester (FAME) analysis. Bacterial isolates from bee bread were also tested for susceptibility to Oxytetracycline HCl, Streptomycin, Tylosin Tartrate, Fumagillin-B, and Ampicillin. FAME analysis identified some of the same core organisms reported by other researchers as well as diverse organisms, which may be environmental bacteria transferred into the colony. Principal component analysis was done on the bacterial banding patterns produced by PCR-DGGE, which suggested that the bacterial flora of bee bread is one of multiple factors involved in the survival of honey bee colonies after the winter season. Some Enterobacteriaceae were susceptible to Oxytetracycline HCl and Streptomycin, which suggests that their roles in the colony should be further researched.