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Varroa

Overview

Varroa destructor
Image courtesy Entomology Today

The danger with Varroa destructor is less with the Varroa itself than for the viruses it vectors into your hive. The viruses known to be transmitted by Varroa destructor include:

• Acute Bee Paralysis Virus (ABPV)
• Deformed Wing Virus (DWV)
• Israeli Acute Paralysis Virus (IAPV)
• Kashmir Bee Virus (KBV)

There are other viruses which are associated with Varroa destructor, and these include:

• Black Queen Cell Virus (BQCV)
• Cloudy Wing Virus
• Sacbrood Virus (SBV)
• Slow Bee Paralysis Virus (SBPV)

Testing for this pest

There are only two tests for which scientific analysis has been completed to identify testing results where action should be taken.

1. Alcohol wash. This is the best, tried-and-true method.
   • The Varroa EasyCheck tool from Véto Pharma is a very easy tool to use.
   • For determining action thresholds, historically that has been 3%. Later guidance has it at:
     • 1% for August and September - due to the rapid growth in the Varroa destructor population heading into Winter, and
     • 2% for all other months.
2. Sugar shake. This was thought to be less harmful to the bees as they would be released alive back into the hive. Later studies have shown that the bees are harmed in the shaking process and their lives are cut shorter as a result.

There are other methods (e.g., washing with soapy water), but those have not been verified regarding the results they may produce.

Integrated Pest Management

Control Methods

Cultural

• Ensure you have strong colonies
• Use entrance reducers
• Reduce colony drift & robbing
  • Place hives near landmarks
  • Spread hives out (10+ yds apart is best)
  • Orient hive entrances in different directions

Genetic

• If the colony is not strong, consider re-queening
• Some queen options include:
  • Varroa Sensitive Hygiene queens
    • Minnesota hygienic
    • Purdue ankle biter
  • Russian queens
  • Saskatraz queens

Treatment Methods

Cultural

• A brood break is a very good option, especially if you find that the hive is queenless. If the infestation of Varroa destructor is high, do consider chemical treatment also.

Chemical

• If the action threshold is exceeded, action should be taken. The Honey Bee Health Coalition has a Varroa Management Decision Tool which is excellent and should be consulted.

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Additional pictures of this

More Information

Published Articles

• Mites and Viruses, by Ryan, Jessica, at the U.S. Department of Agriculture. Published in Bee Culture magazine.

Books and Papers

• Tools for Varroa Management - a Guide to Effective Varroa Sampling & Control by the Honey Bee Health Coalition.