Submitted to: Journal of Apicultural Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2008
Publication Date: 5/1/2008
Citation: Benda, N.D., Boucias, D., Torto, B., Teal, P.E. 2008. Detection and characterization of kodamaea ohmeri associated with small hive beetle Aethina tumida infesting honeybee hives. Journal of Apicultural Research. 47(3):194-201. Interpretive Summary: Yeasts are found in a variety of environments, including in association with insects and plant material. Yeasts have been found in the gut of nitidulid beetles feeding on flowers and mushrooms. Volatiles from yeast fermentation attract nitidulids beetles and serve as cues for egg-laying. The Small Hive Beetle (SHB) is a nitidulid beetle native to Africa. SHB was recently introduced into the U.S.A. and Australia. This beetle invades and destroys honeybee hives, where it feeds and reproduces on the food stores and bee larvae. When honeybee hives become infested with SHB, a slimy coating develops on the comb surface and the honey ferments. Sceintists at the Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville Florida and Department of Entomology and Nematology, University of Florida collected pollen and honey, SHB larvae and adults, and honeybees robbing the hives from SHB-infested hives in Florida and Kenya. When these samples were cultured on growth media, a lawn of yeast grew. The yeast were identified as Kodamaea ohmeri. Differences between the Floridian and Kenyan yeast isolates in other portions of the DNA sequence suggest that the two isolates are different strains of the same yeast species. However, volatile chemicals released by the two isolates were the same and were attractive to SHB. Further sampling and investigation is necessary to understand the relationship between the yeast, the SHB, and the honeybee.
Technical Abstract: Honeybee hive infestation by the Small Hive Beetle (SHB) is associated with fermentation of hive materials. Pollen, beetles, and robbing bees (ten of each) were collected from hives infested with SHB in both Florida and Kenya. Plating of homogenized bodies of beetles and bees and comb swabs resulted in smooth cream-colored yeast colonies that formed pseudomycelial cells as they aged. Fatty acid profiles of yeast isolates from Florida and Kenya most closely matched the profiles of Candida krusei and C. sake, respectively. The DNA sequence of the 28S and 5.8S-ITS2 of both the Florida and Kenya isolates were 99-100% homologous to Kodamaea ohmeri. However, the ITS1 region differed between the two geographic strains. The two strains produced similar volatile profiles which were attractive to SHB and contained compounds also found in honeybee alarm pheromone. Healthy hives were also sampled and found to have multiple yeast species. More investigation is needed to better understand the relationships between the yeast, SHB and honeybee hive.