A New Bacterium-bee Interaction

We isolated a free-living Gram negative bacillus from hemolymph of worker honey bees (Apis mellifera) found separated from winter clusters. In some hives, greater than 90% of the dying bees detached from the winter cluster were found to contain this bacterium in their hemolymph. Throughout the year, the same organism was rarely found in bees engaged in normal hive activities, but was detected in about half of Varroa destructor mites obtained from colonies that housed the septic bees.

Whole-genome nucleotide sequence analysis confirmed this bacterium is a novel strain of Serratia marcescens. We named this organism S. marcescens strain sicaria (sicarius, Latin, meaning assassin), due to its recovery from diseased and dead honey bees. Herein, we refer to this strain of S. marcescens as Ss1.

We report the isolation of Ss1, a novel bacterium obtained from hemolymph of septic adult worker bees. This organism was also found in honey bee drones, carcasses of worker bees found in winterkilled hives, and about half of V. destructor examined.  Ss1 does not appear to have been identified in previous culture-based detection methods, or by sensitive metagenomic approaches applied to characterize a spectrum of microbes relevant to apiculture. Genomic, growth rate, and biochemical properties of Ss1 show clear differences when compared with other Serratia examined. Thus, we believe Ss1 has not previously been described.

We linked this infection to wintertime failure of hives in western Wisconsin, but did not establish causation of hive failure to this bacterium. Additional studies are needed to elucidate the transmission and impact of Ss1 within the complex environment of the hive.

Burritt NL, Foss NJ, Neeno-Eckwall EC, Church JO, Hilger AM, Hildebrand JA, et al. (2016) Sepsis and Hemocyte Loss in Honey Bees (Apis mellifera) Infected with Serratia marcescens Strain Sicaria. PLoS ONE 11(12): e0167752. doi:10.1371/journal.pone.0167752

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html