Development and evaluation of a new effective tool and method for assessing varroadestructor (Acari: Varroidae) mite populations in honey bee colonies

Authors: POSADA-FLOREZ, FRANCISCO - Non ARS Employee; Abban, Samuel; SMITH, IRVING - Retired ARS Employee; Cook, Steven

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2022
Publication Date: 5/12/2022
Citation: Posada-Florez, F., Abban, S.K., Smith, I.B., Cook, S.C. 2022. Development and evaluation of a new effective tool and method for assessing varroadestructor (Acari: Varroidae) mite populations in honey bee colonies . Insects. 13(5):457. https://doi.org/10.3390/insects13050457.
DOI: https://doi.org/10.3390/insects13050457

Interpretive Summary: Varroa destructor mites are harmful ectoparasites of Apis mellifera honey bees. Beekeepers must be diligent and frequently assess the mite populations in their colonies to determine whether treatment of colonies with commercial varroacides are required. Failure to treat honey bee colonies for mite infestations when mite populations reach levels greater than approximately 7 mites per 100 honey bees, can often result in colony collapse. Several methods are available for sampling Varroa numbers in the adult population in honey bees colonies, and each have their advantages and disadvantages. The 'sugar roll' method is a common method but requires using powdered sugar, which can be messy, a respiratory risk to uses, and is restricted to using when humidity levels are low. The alcohol wash method is another common method, but uses potentially toxic to the user and the environment, and employs flammable fluids. A new tool, the Varroa shaker device (VSD) is constructed of PVC pipe that separates into three parts, and uses a fluid together with a shaking motion to dislodge mites from their honey bee hosts. Inside the shaker there are two mesh filters, one with small mesh to capture Varroa mites separate from the honey bees, and one with larger mesh to separate bees from the washing solution. The bees can be shaken with only water as the washing solution. Using the VSD, the recovery of mites from collections of bees is >90%, which is similar to the efficiency reported for both the sugar roll and alcohol wash methods. The VSD can be used in both laboratory and field settings to accurately assess honey bee colonies for their Varroa mite population levels. Given the ease of construction and use, the VSD will greatly simplify this process by both commercial and hobbyist beekeepers

Technical Abstract: A new device for assessing infestations of Varroa destructor mites in honey bee colonies was designed and tested for effective use, and also evaluated against the sugar roll method, which is widely known and used within the beekeeping industry. The Varroa shaker device (VSD) is constructed of PVC pipe that separates into three parts. Inside the shaker there are two mesh sizes; the larger mesh separates the bees from the mites, and the smaller mesh captures the mites. The VSD can be used by shaking bees with only water as the wash solution. The recovery of mites using the VSD is >90%, which is similar to that recorded for using the sugar roll method. Our tests demonstrated that the VSD accurately assessed mite loads when fewer than 250 bees were sampled and shaken with 250 ml of water for one minute. To assure accurate mite counts are achieved with any sampling device, honey bees should be taken from frames with open and/ or capped brood where Varroa mites are more likely to be, as the mites must enter cells containing larvae just prior to capping for their reproduction. The VSD can be used in both laboratory and field settings to accurately assess honey bee colonies for levels of Varroa mite infestation or for collecting live mites for research purposes.