CONTROL STRATEGIES

Control of the Varroa mite must be accomplished using several strategies in concert with each other, similar to integrated pest management techniques commonly used in much of agriculture. Dr. W. Ritter of the German Federal Republic in "Varroa Disease of the Honeybee Apis mellifera," Bee World, Vol. 62, Figure 3. Adult female, showing curvature of body and legs covered by the shell. (SEM photo by H. L. Cromroy and W. C. Carpenter No. 4, 1981, pp. 141-153) suggests a combination of the following: 1.Develop and use more effective treatment methods.

2.Control importation of all species of honey bees.

3.Diagnose infestations in the latent stage (before damage is seen).

4.Isolate infested colonies and those in the immediate area.

5.Control and coordinate treatment of infested colonies.

According to Dr. Ritter, the aim in the German Federal Republic has been to isolate the source of infestation and eradicate the mite in specific localities. However, where it has been spread over a wide area, infestation can at best only be reduced, particularly where there are feral colonies.

He also states that unsuitable highly toxic substances are coming into use and their improper application can contaminate honey. Frequent underdosing can also result in resistant strains of mites, already observed in Japan with phenothiazine. Frequent use of chemicals can also make beekeeping unprofitable, says Dr. Ritter, and a biological control should be a first priority in research for a long-range answer to Varroa control.

CHEMICAL CONTROL

Using chemicals to reduce mite populations can in no way be compared to experiences by beekeepers with TerramycinŽ to control American foulbrood. Therefore, beekeepers are urged not to use chemicals for mite control unless they are registered. Not only is the practice of using unregistered pesticides illegal, but it can also create undesirable effects. Among these are chemically-resistant mites, contaminated wax and honey, and susceptible lines of bees which are more prone to parasitization.

Figure 4. Life Cycle of Varroa Bee Mite.

Again, it is emphasized that USE of any unregistered chemicals by beekeepers is potentially HARMFUL to the beekeeping industry. It should be remembered that chemical control can only be considered a short range objective--more long-range research will be required to find suitable biological control and/or resistant strains of bees.

HONEY CONTAMINATION

Although pesticide use may be impermanent, or at best, changing as more and more chemicals are used for mite control, it is a certainty that more and more honey will be screened for chemical contamination in the future. Should pesticide contamination be found, the resulting adverse publicity could severely damage the honey industry. Witness the use of aldicarb on watermelons and the AlarŽ scare on apples. If there is a tradeoff between mite control and contamination of honey, the bias must be for protecting the name and reputation of honey in the decision-making process.

CONTROL BY MANAGEMENT/ MANIPULATION

Experience has shown that Varroa mite control is possible by reducing the mite populations through management/manipulation. Because the mite needs access to brood to complete its life cycle, bees can be removed from brood (broodless times in cold climates may also be taken advantage of) for a period of days by placing them in packages or empty boxes.

Adult bees removed from infested colonies can be established on foundation or broodless comb that has been stored for a few days and is free of mites. Other manipulations including the use of drone combs as Varroa traps and heat treatment of infested combs may be useful for small-scale beekeepers.

Varroa Mite Treatment Page

Treat for Varroa mites now if you have not already begun treatment. Many people treat twice a year; extract early and treat at the beginning of August and then again as soon as possible in the spring.

I have recently fitted a Varroa screen into the bottom of my hive and have discovered, as I expected that I have Varroa. I counted 15 of the mites on the paper insert, within a twenty four hour period. I plan on using Bayvarol strips.

In 1998, the Varroa mite is as widely spread as flies or mosquitoes. There is NO SUCH choice as "to treat or not treat"! If you want to save your bays, you MUST treat, perhaps only once a year in northern temperate zones and maybe even three times per year in southern temperate zones. I test for varroa mites in March and July and treat if necessary, but I surely don't bother to test in the fall. I TREAT always from October 1st to November 20th. My location is in Maryland near Washington, DC. After 65 years of beekeeping, treating for Varroa is another treatment, BUT NOT OPTIONAL NOW. It is kind of like tying your shoes.

Here in Washington State, USA, I have been recommending a survey be done in late February. If 50 or less mites are found, treat in mid August. If more than 50 or 100 mites are found in any one colony treat in late February (daytime temperatures 50F. or above) for the length of time prescribed on the label or until you put the first super on, whichever occurs first. Even if you can only leave the strips in the hive for two or three weeks in February/March you will lower the Varroa population significantly, and probably not experience any colony collapse in the fall. Use a complete treatment in mid August (>50F.) after removal of honey supers. Once you treat colonies, you probably can rely on only one treatment per year if you are in the northern US. In the UK, follow the Bayvarol label and any recommendations provided by research, or government agencies. Don't rely on beekeeper recommendations because you will here all kinds of them. That is one reason why many beekeepers in the US are continuing to lose significant numbers of colonies to Varroa; they don't follow the label, for economic reasons.h