What Is Israeli Acute Paralysis Virus – Symptoms & Prevention

Israeli acute paralysis virus (IAPV) is a common RNA viral infection in honey bees and wasps. It is linked to colony collapse disorder (CCD), resulting in the loss of bee colonies. The virus typically passes from adult to developing brood.

Different viral strains show varying severity levels, likely due to genetic variation. When bees are infected, their energy-producing processes are heavily affected.

The virus spreads throughout the bee’s body, affecting various brain, gut, and gland tissues.

Symptoms of Israeli acute paralysis virus

The symptoms of IAPV are similar to other diseases like Nosemosis, Kashmir Bee Virus (KBV), Deformed Wing Virus (DWV), Acute Bee Paralysis Virus (ABPV), and Chronic Bee Paralysis Virus (CBPV). Common signs include:

• Adult bees shivering and unable to fly.
• Discolored, darkened bodies.
• Hair loss on the abdomen and thorax.
• Disorientation and rigid paralysis.
• Dead bees outside the hive.
• Bees crawling outside the hive.

How to diagnose IAPV

Beekeepers should not rely on visual observation to diagnose viral infections. Instead, sending samples for lab testing will provide a quick, reliable diagnosis. Tests will 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. 

Related reading: What is Black queen cell virus?

How do bees fight diseases like IAPV?

Honey bees have multiple ways to defend against diseases as individuals and as a colony.

Individual bees have physical barriers, behavioral responses, and an immune system to fight off pathogens.

On top of this, bee colonies have developed “social immunity,” group behaviors that help protect the whole hive.

Examples of social immunity include bees grooming each other and collecting resin to sterilize the hive. Some bees change their chemical scent when sick, prompting other bees to groom them more.

Another way to stop the spread is removing infected bees from the hive.

Prevention

Beekeepers can help prevent IAPV and similar honey bee viruses by maintaining healthy colonies.

• Control varroa mites: The Varroa destructor is an effective vector of Israeli acute paralysis virus in honey bees. The beekeeper should consider eradication methods if mite levels exceed 3 per 100 bees. Learn more about eradicating varroa mites here.
• Reduce stress: Stress impacts a colony’s ability to fight off illness. Beekeepers should keep hive disturbances to a minimum and avoid opening hives in cold weather.
• Keep bees nourished: During nectar dearth and food shortages, provide sugar syrup or pollen substitutes to keep the hive strong and healthy.
• Consider bee breeds: Some bee stocks have excellent housekeeping behavior and have better resistance to disease and pests. For example, Russian bees instinctively suppress varroa mite populations, reducing viral spread.
• Hygienic beekeeping practices: Maintain clean hive tools and equipment to reduce spread; never move frames from sick to healthy ones or reuse equipment from dead hives; space out hives to reduce drifting behavior.
• 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 IAPV transmitted?

The Israeli Acute Paralysis 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).

During mating, drones may pass the virus to a queen. Future eggs will also have the disease.

The virus also contaminates food sources like flowers and honey. As foraging bees go about their business, they can quickly become infected.

10 facts about IAPV

1. The IAPV is classified as part of the dicistroviridae family.
2. The disease was first discovered in Israel apiaries in 2004.
3. It is related to Chronic Bee Paralysis Virus (CBPV), Kashmir Bee Virus (KBV), and Acute Bee Paralysis Virus (ABPV).
4. It has been identified as a significant factor associated with CCD.
5. The mite Varroa destructor, another major threat to bees, also helps spread the infection.
6. The virus infects eggs, larvae, adult workers, drones, and queens.
7. IAPV also exists in bee food and the insect’s waste.
8. The virus is in many countries including the United States, Australia, Argentina, China, Japan, Japan, Brazil, Poland, Russia, Spain, Italy, and South Korea.
9. Strong bee colonies had fewer cases of IAPV than weak colonies.
10. Weak colonies see the virus peak in winter and often don’t survive until spring. Strong colonies often make it through winter successfully.

Treatment

Although some promising treatments are currently being developed for IAPV, no reliable cure is available to beekeepers.

Caffeine is showing some promise as a treatment. Researchers studied how plant-made chemicals, called phytochemicals, affect honey bees infected with a virus.

They found that caffeine can help infected bees live longer when used at levels naturally found in flowers. However, it’s not a complete cure for the virus. This discovery suggests caffeine could potentially treat viral infections in bees and warrants further study. Source.

Do chemical treatments work?

Canadian researchers tested Apivar and Thymovar to see how well they protect honey bee colonies from mites (V. destructor) and viruses.

Results showed that Apivar was more effective than Thymovar in reducing mite infestation. However, neither treatment had a significant effect on the viral infections present in the colonies. Read more>

What about thermal treatment?

A study in partnership with MPI NZ investigated how to treat IAPV in honey bees, specifically in pupae and honey. They used thermal treatments to see if they could kill the virus.

Various heat treatments were tested. The most effective were at 70°C for 1hr 48min and 65°C for 6 or 8 hours. These treatments managed to deactivate the virus in all samples tested. However, other temperature-duration combinations either allowed the virus to survive or were deemed impractical for large-scale use.

The study is the first to show that thermal treatments can effectively deactivate IAPV in honey. More research is needed to confirm these findings in large-scale honey batches. Download the research>