January 19, 2014
Intestinal Parasite More Harmful To Male Honey Bees Than Females
redOrbit Staff & Wire Reports - Your Universe Online
Male European honey bees are far more susceptible to a widespread fungal intestinal parasite than female members of the species, according to new research appearing in the January 17 edition of the open-access scientific journal PLoS ONE.The parasite, which is known as Nosema ceranae, originated in Asia but has spread rapidly to all corners of the world in recent years and could be partially responsible for the elevated number of colony deaths being reported in several regions of the northern hemisphere, researchers from the University of Bern explained in a statement.
These findings indicate that male honey bees (also known as drones), which are essential to bee colony reproduction, are more susceptible to a well-distributed parasite. The two female types of bees (workers and queens) are each diploid and contain two copies of each chromosome, while the drones are haploid and have only one chromosome set.
“The haploid susceptibility hypothesis predicts that haploid males are more prone to disease compared to their diploid female counterparts because dominant genes on one chromosome copy have the opportunity to mask mutated genes on the other copy in diploid organisms,” the university said.
In the study, University of Bern doctoral student Gina Tanner and her colleagues demonstrated that the male honey bees die more quickly and respond worse if they come in contact the fungal parasite than either female workers or queen honey bees.
“Although drones do not perform important colony maintenance functions like cleaning and feeding like the workers, they are responsible for mating with queens so that the next generation of honey bees can be produced within a colony,” added Tanner, who is also working with the Institute of Bee Health during the final year of her Ph. D. studies. “Without strong, fit drones, the chance of successful matings with queens could be severely compromised.”
“Recent studies, mainly coming out of the United States, suggest that queen failure is a major cause of colony death. Early death of queens could be the result of queens not obtaining sufficient quantity and quality of sperm from drones during mating,” the university added. The research originated from the European Union-funded research consortium BEE DOC (Bees in Europe and the Decline of Honeybee colonies).
In addition to Tanner, the research team included Marion M. Mehmann, Orlando Yañez, and Peter Neumann of the Swiss Bee Research Centre; Geoffrey R. Williams from the Dalhousie University Department of Biology; Joachim R. de Miranda from the Swedish University of Agricultural Sciences Department of Ecology; and Peter Neumann of the University of Pretoria Department of Zoology and Entomology’s Social Insect Research Group.