Beehive Medical Spotlight: Chronic Bee Paralysis Virus "Black Back"
Updated: Jun 20, 2020
This week for our Hive Medical Spotlight is the Chronic Bee Paralysis Virus (CBPV). This virus uses Varroa as a vector for transmission. Once a hive is infected it takes a few days for symptoms to show up.
Commonly called "Black Back" or "Hairless Black". This virus is commonly always in a hive and is in-apparent. CBPV is an unclassified virus from a single strand of RNA with wo distinct syndromes associated with this virus. Type 1 and type 2 respectively. In an apiary with an outbreak not all colonies will develop the disease. Affected colonies are usually strong and crowded, typically. CBPV does not usually cause large amounts of mortality. However, it will weaken colonies and if it persists into the fall it may cause a colony to collapse. Type 1 syndrome is the most serious of the two and is the paralysis syndrome.
It has been observed in France that bees drinking honeydew (from aphids) frequently develop this disease and therefore it is also a vector. Signs/symptoms include: abnormal trembling of wings and bodies; ataxia(impaired coordination), circling, inability to take off or fly, manifested by bees crawling on the ground and up stems; bloated abdomens; mortality within a few days. At the colony level bees can be seen crawling on the ground with outspread (not K-Wing) wings and in front of around and the floor of the hive.
Type 2 affected bees tend to be smaller with a shortened abdomen, the Honeybees become hairless and appear dark and shiny, glossy in appearance. In the beginning stages bees are able to fly, but soon begin crawling and trembling, looking abnormal to observant Beekeeper's. Type 2 usually appears in the spring and summer in the same conditions as type 1. Conditions for this virus to flare up usually include inclement weather as a factor. It can significantly weaken a colony, although it is considered to be a minor problem. Only a few type 2 bees are observed within the colony.
Research is ongoing if it is two separate strains or one strain with different stages. It is believed that this virus is readily transmitted through food and pheromone sharing by mouth part contact.
This virus is found in all stages of bees from eggs to adults. The prognosis that this spontaneously disappears on its own is very good, but if the disease persists into autumn the chances of survival drop.
Treatments include minimizing transmission and reducing viral loads within colonies to help the bees fight the virus. Optimal Varroa control is another tool as well as overwintering without honeydew, limiting overcrowded colonies, healthy selected queens and re-queening.
Clean the front and surrounding areas of the hive by removing dead bees as they remain a vector of disease with other bees coming in contact with them, namely the undertaker and house cleaner bees.
Apply the shock swarm technique to lower the viral load within the colony (find the queen and cage her, set aside, shake every single bee off the frames in front of the hive and reassemble the hive). Be mindful that this will cause a large cloud of upset bees. Apply this method once every four days for two weeks to help shake off the more diseased bees and reduce viral load and transmission rates.
Re-queen the colony with a new queen or if possible a CBPV resistant queen if one can be found.
Treatment of the hive for Varroa is always recommended if you have threshold levels of Varroa. Remember not to over treat for prevention. Hives frequently can come down with this virus, but if you're keeping up with Varroa and making sure your colonies are not overly crowded, the situation should resolve on its own.
Beekeeping is more of an art than a science, we certainly apply science, but learning what to watch for, and what a problem is can take some learning. When levels of this virus are rising and more and more are noticed with black back, or more are seen with the debilitating shaking syndrome, then helping to reduce the viral load is the cure, but again, vigilance is needed. Just remember, this virus is usually not fatal, and cannot simply be cured, just managed back to a state where the hive enters homeostasis with the virus, just as we humans are in homeostasis with the cold virus, we always have it, but when the body is thrown out of balance the virus becomes active, CBPV is the same in general.
Thank you for taking the time to read our blog and I hope this information is useful to you. Remember to follow us here on our blog for more information, as well as on our Facebook Group and Business Page: Mystic Earth Apiary LLC. Good luck everyone, this seems to be a year where this virus is more prevalent than in previous years. Source Citation: Honeybee Veterinary Medicine: Apis mellifera L. (2015) Nicolas Vidal-Naquet. pg. 71-75. 5M Publishing.