What Is Kashmir Bee Virus? A Beekeeper’s Guide
Kashmir bee virus (KBV) is a disease that impacts honey bees at all stages of development. While healthy hives often keep this infection under control, it has a greater impact on weak hives.
KBV is a genetic relative of Acute Bee Paralysis Virus, both belonging to the Dicistroviridae family. The two viruses can infect the same host or the same bee colony.
The disease is endemic in various countries, including the United States, Australia, and Italy. However, it is less commonly reported in much of Europe. KBV is not as widespread as similar bee diseases like Deformed Wing Virus.
What are the symptoms of KBV?
Kashmir bee virus doesn’t typically result in large numbers of deaths. It is not usually associated with disease symptoms unless the colony has other pathogens or parasites. Source.
Symptoms to look for in the colony include:
- Older adult bees appearing greasy or oily.
- Adult bees shivering and unable to fly.
- Hair loss on the abdomen and thorax.
- Discolored, darkened bodies.
- Dead or crawling bees outside the hive.
- Disorientation and rigid paralysis.
How to diagnose KBV
Beekeepers should not rely on visual observation to diagnose viral infections. Instead, sending samples for lab testing provides a quick, reliable diagnosis. Tests reveal the type of virus along with the levels of disease.
The polymerase chain reaction (PCR) test effectively identifies positive cases. It rapidly makes millions or billions of copies of a DNA sample, enabling scientists to study a disease in detail.
Beekeepers should follow these steps to get the problem diagnosed:
- Select ten sick-looking bees still alive from near the hive’s entrance.
- Place them in a paper envelope or bag labeled with your name and hive number. Avoid containers or plastic bags.
- Freeze the bag for 24 hours, then send it to a local testing office.
Beekeepers with multiple hives can take a composite sample from different colonies.
Recommended reading about similar viruses:
How do bees fight diseases like KBV?
Honey bees have various options when defending diseases as individuals and as a colony.
Individual bees have physical barriers, behavioral responses, and an immune system to fight off pathogens.
Bee colonies have also developed “social immunity,” group behaviors that assist with hive protection. Bees often groom each other and collect resin to sterilize the hive. Some bees change their chemical fragrance when ill, which alerts other bees to groom them.
Another way the colony stops disease spread is by removing infected bees from the hive.
Prevention
Beekeepers can help prevent KBV and similar honey bee viruses by maintaining healthy colonies.
Varroa mite eradication: The Varroa destructor is a vector of the Kashmir bee virus in honey bees. Consider treatment if mite levels exceed 3 per 100 bees. Learn more about getting rid of varroa mites here.
Reduce stress: Stress impacts a colony’s ability to fight illness. Always keep hive disturbances to a minimum and avoid opening hives in cold weather.
Feed the colony: Provide pollen substitutes or sugar syrup during food shortages to keep the hive healthy.
Requeen: Some bee stocks have excellent housekeeping behavior with better resistance to pests and disease. Russian bees instinctively suppress varroa mite populations, leading to reduced viral spread.
Hygienic beekeeping: Maintain clean equipment and tools to reduce the spread and never reuse equipment from dead hives. Space out hives to reduce drifting.
Reduce chemicals: Restrict hive treatments like miticides, which may reduce bee virus tolerance.
Keep a watchful eye on other bee pests and diseases. If Nosema disease is present, then treat it.
How is KBV transmitted?
The Kashmir bee virus is transmitted from bee to bee within the colony and amongst other hives. It spreads from adult nurse bees to their brood during feeding (trophallaxis).
The virus also contaminates food sources like flowers and honey. As foraging bees go about their business, they can quickly become infected.
During mating, drones may pass the virus to a queen. Future eggs will also have the disease.
5 facts about KBV
- Researchers consider Kashmir bee virus a virulent strain under laboratory conditions.
- There is still much to learn about the virus’ severity in the field.
- The infection is a positive sense ssRNA virus within the Cripavirus genus.
- Disease transmission results from the movement of varroa mites. It is also transferred when adult bees and their babies eat contaminated food sources like pollen, honey, and royal jelly.
- KBV initially infected the easter honey bee (Apis cerana) until it jumped species to the western honey bee (Apis mellifera).
Treatment
Although some promising treatments are currently being developed for KBV, no reliable cure is available to beekeepers.
Do you enjoy learning about the challenges that bees face? We recommend reading our article about common bee threats. It is essential reading for beekeepers wanting to help their colonies thrive.
