March 14, 2012

Promiscuous Bee Queen Ensures Healthier Bee Colony

A new Wellesley College study shows that a queen bee´s promiscuity benefits the hive. Dr. Heather Mattila studied the lives of bee colonies and discovered that the more genetically diverse the worker bee, the healthier they are. These bees become so genetically diverse when the queen bee mates with multiple bees.

Research in bees has been growing in recent years in order to better understand and protect them. According to the U.S. Department of Agriculture, the honey bee population has been decreasing by 30% each year since 2007 due to Colony Collapse Disorder (CCD). As pollinators, bees play a very important role in agriculture and food supply. If the bees continue to disappear, food shortages could occur.

The cause of CCD remains a mystery, but researchers like Dr. Mattila have long believed that genetic diversity within a colony could be the key to healthier and heartier bees.

This new study provides insight on how the bee colonies become so genetically diverse.
Dr. Mattila and L.G. Newton, a microbiologist at Indiana University led the research team that compared two different groups of honey bee colonies. The first group colonies was comprised of genetically diverse bees, produced by a a promiscuous bee queen that had taken 15 different mates. The second group of bee colonies largely shared the same genetics, produced by a queen who had only taken one mate. By using a advanced molecular technique that had never been used before, 16S rRNA, the team studied active bacteria in the honey bees across the colonies. What the research team found surprised them.

According to their research, the genetically diverse honey bee colonies showed 1,105 different species of active bacteria. These bacteria were much more varied and in greater number than the genetically uniform colonies of honey bees, in whom researchers only found 781 species of bacteria. In addition, the active bacteria found within the first group of honey bees consisted of 40% potentially helpful bacteria. The bacteria in the second group of honey bees, however, consisted of of 127% more potential pathogens.

The team then made another discovery: The genetically diverse group of honey bees also carried 4 bacteria that are usually found in other animals (such as cows and humans) to aid in food digestion. Many of these bacteria had never been found in honey bees before.
“We´ve never known how healthier bees are generated by genetic diversity, but this study provides strong clues,” said Mattila. “Our findings suggest that genetically diverse honey bees have the advantage of broader microbial communities, which may be key to improving colony health and nutrition–and to understanding factors that can mitigate honey bee decline.”

Newton said in the press release, “We found that genetically diverse colonies have a more diverse, healthful, active bacterial community. Conversely, genetically uniform colonies had a higher activity of potential plant and animal pathogens in their digestive tracts.”

Just like humans, bees depend on healthy bacteria in their guts to ward off disease and infection, as well as digest and ferment food. In bees, these healthy bacteria are used to transform pollen collected by worker bees into a nutritious food substance called “bee bread”.

According to Mattila, this promiscuity in bee queens is unusual in other parts of the insect world: “It shows one of the many ways that the function of a honey bee colony is enhanced when a queen mates promiscuously, which is an unusual behavior for social insects. Most bees, ants, and wasp queens mate singly and produce colonies of closely related, single family workers.”

Dr. Heather Mattila shares her work with other bee researchers and bee enthusiasts, hoping that together they will be able to prevent CCD.


On the Net: