FIBKA Guidelines on Varroa Destructor - Integrated Control Programme

The following Guidelines have been reviewed. There has been good feedback from beekeepers that find them easy to use and effective in dealing with the varroa threat. The Executive Council has again re-affirmed their confidence in them at their meeting on 12th of December 2009. Those Guidelines are subject to review on an annual basis.

1. Open Mesh Floor:

The hive should be placed on an OMF with top insulation in roof of the hive. OMF helps to lower mite population as well as assist in the early build up of the stock in spring. The insert should be used for monitoring the average daily mite drop throughout the year.

2. The average daily mite drop level

The average daily mite drop level determines whether treatment is required as follows:

3. Control using approved treatments:

There are only two chemical treatments licensed for use in Ireland. They are Bayvarol and Apiguard. Bayvarol has been a most efficient treatment for Varroa. However, there are signs of resistance to Bayvarol developing in the Island of Ireland. In order to retain Bayvarol within the armoury of treatments total reliance must no longer be made on it. This means that Apiguard must be used more frequently:

(a) Irish experience has shown that Apiguard can be very effective if the proper conditions are used: A shallow eke of 20 mm should be placed above the brood box to accommodate the tray. Two applications of one tray of 50g Apiguard gel per colony at a two week interval. Leave the product in the colony until the tray is empty. Maximum of two treatments per year. Treat in early Autumn as the maximum ambient temperature should be above 15°C.

(b) Average daily mite drop should be checked after any treatment to find out if the treatment has been effective. If resistance is detected or suspected notify the Dept of Agr. and Food, Crop Production and Safety Division, Backweston Main reception, Young's Cross, Celbridge, Co Kildare. Tel No 01-6157100 (the format for email to the Department is firstname.surname@agriculture.gov.ie)

Biotechnical control methods

Biotechnical control methods should be undertaken in late Spring as a follow up to Apiguard. Some commonly used biotechnical methods are as follows: (From "Managing Varroa" - DEFRA crown copyright.)

Drone Brood Trapping for heavy infested colonies during the foraging season:

1. Place two shallow combs in the brood chamber in spring and allow the bees to build natural drone comb beneath them. A good time to put these in the colony is when the queen first begins to lay up drone brood. Place the combs in the colony one at a time and alternate at 9-day intervals (a run of alternating pair of frames). Another option is to use an empty deep frame fitted with a starter strip of foundation to avoid possible misshapen comb.
2. When a drone comb is full of sealed drone brood (infested with varroa), cut it from the frame before it emerges and destroy it. Failure to do this will breed more mites. The frame can be re-used immediately.
3. Repeat the process several times in the season for maximum effectiveness.

Comb trapping

1. Confine the queen to a worker Comb "A" using a purpose-made comb-cage (available commercially).
2. After 9 days confine her to a new, empty comb 'B' and leave comb 'A' in the brood chamber to become infested with mites.
3. After a further 9 days remove comb 'A' (now sealed). Confine the queen to a new comb 'C', leaving comb 'B' in the brood chamber.
4. After 9 more days remove comb 'B'. Release the queen (or re-queen by introducing another queen) leaving comb 'C' in the brood chamber.
5. After 9 more days, remove comb

Artificial Swarm

1. Move parent colony to one side of the original site, at least 4 metres away.
2. Place a second hive containing newly drawn combs and the queen (alone) on the original site to house the artificial swarm. Foragers will return to this hive creating the artificial swarm.
3. After 9 days remove all but one queen cell from the parent colony The cell can be protected in a queen cell nursery cage which prevents the virgin queen from leaving the hive to mate, but allows worker bees access to care for her.
4. After 3 weeks all brood in the parent colony will have hatched. Transfer two bait combs of unsealed brood from the artificial swarm to the parent colony, and when they are capped, remove and destroy them. At this stage, cull the virgin and introduce a new queen to the parent colony
5. The old queen in the swarm can later be removed and the two colonies reunited.

Open mesh Floors

1. Fit a mesh varroa-monitoring floor (without a collection tray) to the hive.
2. Many of the mites falling from the colony are alive. The mesh floor allows these to drop out of the hive rather than returning to the colony.
3. Used in conjunction with other control methods this method helps keep mite numbers down.

Placing hives in a sunny location

There is evidence that by simply placing an apiary in a sunny instead of an additional shaded location, a beekeeper can expect significantly reduced rates of varroa mite population growth

Dusting with Icing Sugar

1. Have the hive on a Varroa screen or preferably and Open Mesh Floor.
2. Use pure icing sugar
3. Sift 225 gm of icing sugar before use and place it in a container and take to the hives.
4. Close the monitoring screen so that the icing sugar does not fall to the ground.
5. Sift the icing sugar into the hive over the top bars of the frames and onto the bees in the 'seams'. A sugar sifter is an ideal tool for this or a CLEAN talcum powder container whereby the sugar can be puffed onto the bees. There is no need to remove the frames from the brood box.
6. After a day remove the insert sheet and destroy.
7. Another method is by attaching a screened box with solid floor to the front of a hive and using a commercial bee repellent to run bees into the box The box with bees is then removed, closed and the bees dusted with 225 g powdered sugar and gently rolled to ensure an even distribution of sugar After 20-30 minutes, during which bees are grooming themselves, the box is gently bounced over white paper to dislodge and remove mites from the mix Then the bees are returned to their colony by dumping them into an empty hive body placed over the brood nest The authors report a mite removal rate of over 76% with this method. Adapted From an Article by Keith Delaplane in Bee Craft

4. Monitor by using the uncapping fork on drone brood.

Uncap 100 drone cells. If level of infestation exceeds 10% then treat immediately

THE NEEDLESS REMOVAL OF DRONE BROOD SHOULD BE AVOIDED AS DRONES ARE NEEDED FOR QUEEN MATING.

5. Oxalic acid can be a useful mid winter treatment when there is no brood in the hive.

The recommended dosage of oxalic acid dihydrate for Northern Europe according to the European Group for Integrated Varroa Control, 2000 is 4.5% oxalic acid dihydrate in a sugar water solution (1:1 mixture). Add 45 grams of oxalic acid dihydrate to one litre of the sugar water solution.

Dosage rate is: 20-25 ml on a small colony, 25-30 ml on a medium colony and 30-35 ml on a large colony.

Note: Molecular formula of oxalic acid dihydrate is: C2H2O4.2(H2O), Relative Molecular Mass = 126.06

IT IS ILLEGAL TO DO THIS WITHOUT A PRESCRIPTION FROM A VETERINARY SURGEON WHO IS PREPARED TO USE THE 'CASCADE' METHODOLOGY.

6. Change three or four frames in the brood box annually to avoid the build up of residue in the wax.

7. DO NOT IMPORT QUEENS OR PACKAGE BEES for fear of introducing a resistant strain of varroa mite or other bee diseases and pests eg. Kashmir bee virus or Small Hive Beetle into Ireland.

8. When resistance becomes widespread you will have to stop using pyrethroids and rely on alternatives. Keep up to date with new developments in the control of varroa - as the situation develops you need to make sure you have the latest information to help you respond appropriately

A Print Version (Word) of this Guideline is available here