Immunity to Bacterial Infections in Honey Bees
by Peter Kilian
Honey bees constantly struggle against various bacterial and fungal species. For example, Nosema species are very detrimental parasitic fungi that infect honey bees and can cause great harm to an entire colony in a very short amount of time. A hive that is heavily infected with nosema will often collapse, leading to robbing behavior by other colonies and a potential spread of nosema to neighboring hives. While Nosema is very dangerous to the health of a beehive, bees do have a natural defense mechanism. A 2013 study out of the University of Würzburg in Würzburg, Germany explores how bees naturally defend against nosema and other microorganism attackers.
Testing for Immunity
In the experiment mentioned above, bees were infected with bacterial loads at varying stages of life. Bacteria were allowed to grow in the honey bees for measured periods of time. At the end of the growth period the final amount of bacteria present in the honey bees was measured. The results are quite interesting! The researchers found that honey bee larvae are able to cope with bacterial infection, by generating antibodies. These antibodies decrease the amount bacteria present in the larvae over the infection period. This suggests that the bee larvae must have some defenses in place to fight off early bacterial infection. In other words, they have some innate immunity. It is important to note that in this experiment, E. Coli was used, which does act differently than Nosema. Despite this, it is possible that larval bees could have immunity to other microbes.
Additionally, researchers also learned that honey bee drones are similarly protected by a powerful innate immune system. When infected with a bacterial load, the drones were able to fight off most of the infection during the incubation period. This means that the drones must have a powerful immune response that can deal with the foreign bacteria as it enters the body.
The results of this this study are very important. Applying similar methods to test for immunity to other microbes, such as Nosema spp., will help shed light on how bees might resist the myriad of diseases that pose a threat.
To access the full research article for free, visit plosone.org.
Peter Kilian is a first year beekeeper conducting research with the Urban Bee Lab and with Northeastern University, where he studies biology. He also works as a field beekeeper with our partner, The Best Bees Company.