APIS Volume 6, Number 6, June 1988

eZine lover (@eZine)

Published in 

APIS

 · 1 Nov 2023

In this issue

• Task Force Deliberations on Varroa
• Developing Thresholds for Varroa
• Bees in Citrus: Fewer with Varroa

TASK FORCE DELIBERATIONS ON VARROA: CHANGING RULES

[Editor's note: Included for historical purposes only. Most of what is said here has happened and is in place. For most current information, contact the Florida Chief Apiary Inspector]

The Varroa mite task force, appointed by Agriculture Commissioner Conner, met recently to deliberate modifying regulations on the Florida movement quarantine. The time was appropriate considering the decision by USDA-APHIS to revoke the national movement quarantine. The agenda consisted of a present description of Federal and state efforts to control movement of colonies, and discussion of ongoing research efforts.

Interest continues in establishing a national movement quarantine and there appears to be some effort being expended to reexamine the issue. A big problem continues to be agreement by all segments of the beekeeping industry on the specifics of such a quarantine. Lacking this, it appears unlikely that another will be proposed.

Frank Robinson, chairman of Florida's Varroa Task Force and secretary- treasurer of the American Beekeeping Federation, suggested that some arrangement might still be made with USDA-APHIS, if industry personnel and regulators could agree on the following basic facts:

• A. Varroa will eventually spread throughout this country.
• B. Eradication isn't possible and the best that can be hoped for is to maybe slow advance of the pest.
• C. Chemical treatments are not going to achieve a "mite free" status so keeping populations of mites below some economic threshold level should be the goal.
• D. The longest possible interval between treatments and the least numbers of colonies that are treated should be the goal of any control program.
• E. Residues in honey and/or wax may be unavoidable, but will almost be assured if regulations require or even encourage "preventative" treatments.
• F. As far as possible, the normal movement of colonies, queens and package bees must be a goal of any program.

After a great deal of discussion, the Task Force was able to agree on the majority of the above tenets for the state. It recommended that the Commissioner "lift the quarantine on movement of honeybees and beekeeping equipment throughout Florida."

The bases for the recommendation are:

1. Current efforts at controlling movement are not effective. Florida, as of May 27, had twenty-nine infested counties involving some 11,000 colonies. Too few law enforcement officers and bee inspectors are employed to adequately cover the entire state. Bee inspectors' energies are so drained by Varroa inspections they are unable to go about the traditional business of controlling American foulbrood, which is on the rise. Hobbyist beekeepers are receiving less emphasis in Varroa and other diseases' control because most resources are being consumed by demands from commercial operators to move bees. Movement is the basis for most commercial beekeeping in Florida. If colonies can't be moved, then many beekeepers are out of business, mites or no mites.
2. Fluvalinate treatments do not control one hundred percent of mites in a colony and some, therefore, survive. Mites end up being moved in spite of everything. Beyond managed colonies, Varroa has also been found on a carpenter bee, bumble bee and beetle in Florida. An "unusual, green-eyed bee" in a box of carnations shipped from Colombia was also infested, as was an Africanized swarm taken off a ship from Guatemala.
3. Applying pesticide to all colonies in a yard when a single mite is detected in one colony (by the ether roll test) is in the long run detrimental. History of the synthetic pyrethroids, of which fluvalinate is one, suggests that resistance by mites can build up rapidly in an environment where these chemicals are widely used. In addition, the more pesticide that's in the environment, the more likely it will contaminate honey and wax. Applying pesticide inside a colony just to be able to move is not an appropriate tradeoff given that all mites are not killed and the risk of chemical contamination of hive products is increased.

Lifting the quarantine is not without risk to Florida beekeepers. No regulations concerning movement within the state will invariably mean that Varroa will spread unimpeded throughout Florida. If within-state movement is not controlled, there is a possibility that some states may not accept Florida bees under any conditions. Finally, there is a danger that Florida could become a "dumping ground" for infested colonies.

Modifying the present moving criteria will also be discussed at the Honey Bee Technical Council meeting. Specific questions are expected to be raised concerning: percentage of bees moving into the state to be checked; length of time a certificate is valid; recommended treatment times; levels of sampling (by the yard or outfit); netting requirements; sampling of non-commercial and non-migratory beekeepers; and certification requirements for queens and package bees.

At this time, the movement quarantine still remains in effect. For the most up-to-date information, consult your local bee inspector. In general, current requirements include:

1. All bees entering state certified by state of origin as apparently mite free based on original USDA requirement of 5% of colonies sampled by ether roll technique.
2. If for any reason the state of origin cannot check for Varroa, bees are allowed to come in under quarantine to a drop yard. They are then sampled and checked by Florida bee inspectors at above level before movement is allowed.
3. Bees moving within Florida are checked at 10% of colonies using ether roll. If negative, they may move anywhere for 90 days after certification. A separate certificate must be obtained for each yard moved each time it is moved. Netting is required.
4. Positive yards must be treated before movement. Present treatment is with fluvalinate Apistan strips for 21 days. Movement within Florida can occur after treatment has been in place for 7 days with completion of treatment at destination.
5. Bees located within 1 1/2 miles of a known positive yard are checked at 20% of colonies before movement is allowed.
6. Bees moving out of state are checked at 20% of colonies unless required otherwise by destination state.
7. Foulbrood inspection is currently done at the same time and percentage as Varroa.

ON THRESHOLDS

A major problem in devising regulatory and control programs for Varroa is establishing realistic levels or thresholds of infestation. A basic building block of integrated pest management systems is to treat with pesticide only when the population builds up and exceeds an "economic threshold." This is the level above which it is deemed cost effective to apply pesticides. Below this threshold, the damage to the crop is less costly than pesticide treatment. For certain plants, this might be so many caterpillars per leaf or so much percentage of leaf damage.

The economic threshold for Varroa in a bee colony in Florida has yet to be determined. One problem is that the sampling procedures are not uniform and the results are variable. The two most popular methods: ether roll and fluvalinate impregnated plastic strips do not yet provide enough information to determine an adequate threshold. Is 25 mites per roll jar filled with 500 bees (.05 mites/bee) enough of an infestation to treat? How does this translate into damage in terms of honey production lost? Is it worth it to purchase and apply plastic strips at this level? At present, this would be a guess at best and debatable. What about the economic damage of 25 mites found dead on the bottom board after insertion of a fluvalinate impregnated plastic strip? Given the reputation of Varroa, would any beekeeper wait until this level is attained before treating? Those having a clear idea of the costs involved might.

If the experiences of other agriculturalists are any kind of a guide, however, many beekeepers would not wait very long before treating, no matter what the economic threshold level might be. This is especially true when a relatively innocuous material like fluvalinate is readily available. Traditional use of Terramycin as a control of American foulbrood also mitigates waiting very long and encourages preventative treatments, which are clearly counterproductive.

For regulators, on the other hand, 25 mites per roll jar or on the bottom board is not acceptable. This level will not prevent the spread of mites. What would be the regulatory threshold? In Florida, it is now a single mite in a jar from one colony. This threshold now requires all colonies in a yard to be treated with fluvalinate. However, at this low level of infestation, the roll technique may show mites on one occasion and not on another. Thus, mites probably will still be spread because of sampling variablility and the fact that treatment with fluvalinate cannot guarantee colonies free of mites. Research has shown fluvalinate to be more effective at detecting mites, but regulators in Florida rely on the roll technique. It is reasonably efficient and provides an immediate answer. Use of fluvalinate requires at least two trips to a colony, delays diagnosis and also adds to the amount of pesticide in the bees' environment.

Another threshold that bears examination is contaminants in honey. On a national basis, no residues of pesticide, herbicide or other chemicals are currently allowable in honey. Florida has set a level on bromine residues, but this is the only material I know of where some tolerance is established. What about a tolerance for chemicals used to reduce Varroa populations? There are none. Zero tolerance is a two-edged sword; good for industry public relations, but very damaging if any chemicals, no matter the amount, are found. Witness the recent furor over zero tolerance for controlled substances on the high seas. Billion and in certain cases, trillion parts per million are now common levels of chemicals that can be detected.

Until reasonable thresholds are established in the above areas, regulators/beekeepers/educators will clearly be "behind the eight ball" in determining any course of action to control the spread of Varroa. Meanwhile the pest continues to spread devastation inside bee colonies and confusion amongst the beekeeping community.

WHERE ARE THE BEES?

Word comes that restriction on movement of colonies in Florida last season was responsible for fewer colonies being brought into citrus groves. And managers and owners are asking where they are. They are sensitized to the fact that bees mean pollination and potential profits. Although the traditional belief is that citrus growers won't pay for pollination, they are clearly nervous when bees are in short supply. This also applies to states in the northeast, like Maine, where farmers rely heavily on bees for pollinating a wide variety of crops. Does this mean bees are finally getting some kind of respect?

There's a lot of evidence that this is the case. Maine continues to certify bee movement from Florida, in spite of the state's heavily Varroa infested reputation. A sojourn to the capital by Florida beekeeping industry leaders revealed that a good deal of support by growers and other groups exists to help solve beekeeping problems. The message that bees are important to agriculturalists has been received and processed. Now is the time to capitalize on it with realistic requests for help from the rest of the agricultural community.

Sincerely,

Malcolm T. Sanford
Bldg 970, Box 110620
University of Florida
Gainesville, FL 32611-0620
Phone (352) 392-1801, Ext. 143 FAX: (352)-392-0190
http://www.ifas.ufl.edu/~mts/apishtm/apis.htm
INTERNET Address: MTS@GNV.IFAS.UFL.EDU
©1988 M.T. Sanford "All Rights Reserved