TOOLS FOR VARROA MANAGEMENT A GUIDE TO EFFECTIVE VARROA SAMPLING & CONTROL HEALTHY BEES · HEALTHY PEOPLE · HEALTHY PLANET™ ™ First Edition 2015 Copyright © 2015 The Keystone Policy Center on behalf of The Honey Bee Health Coalition This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. The Honey Bee Health Coalition offers this Guide free of charge, and permits others to duplicate and distribute it. You may not use the material for commercial purposes. If you distribute the Guide, please give appropriate credit to the Coalition as its author. We encourage readers to distribute it to beekeepers and anyone else who can benefit from it. TABLE OF CONTENTS INTRODUCTION 3 Integrated Pest Management and Varroa Mite Control 4 ABOUT VARROA MITES 5 Honey Bee and Varroa Mite Seasonal Development 5 MONITORING VARROA MITE POPULATIONS 6 Recommended Sampling Methods 6 Interpreting Sample Findings 8 Alternate Sampling Methods for Varroa Assessment 9 SELECTING CONTROL METHODS 9 Summary of Controls Discussed in this Guide 10 Control Options by Seasonal Phase 10 DESCRIPTIONS OF VARROA CONTROLS 13 Chemical Controls 13 Non-Chemical Controls 17 ABOUT THE HONEY BEE HEALTH COALITION 21 ADDITIONAL RESOURCES 22 General information 22 Sampling 22 Integrated Pest Management 23 Other resources 24 Older material 24 Disclaimer The Honey Bee Health Coalition, its members, Keystone Policy Center, and their respective representatives, directors, officers, agents, independent contractors, and employees (hereinafter collectively referred to as “Authors”) disclaim any liability for loss or damage resulting from the use and application of any mite treatment product or Varroa control technique referred to or described in this Guide. The treatment products and control techniques referred to in this Guide are generally recognized as beekeeper standard practice and specific pesticides are labeled for such use. No warranty of accuracy or reliability is given, and the Authors shall not be responsible to any person for any loss or damage, including by reason of negligence. Nothing in this Guide is intended as an endorsement or recommendation of any product or technique. Readers should exercise their own judgment in researching information and making decisions about their respective situations. It is the responsibility of the reader to evaluate the accuracy, completeness or utility of any information or other content of this Guide. Readers desiring further information are encouraged to consult their local university extension service. INTRODUCTION Every honey bee colony in the continental United States and Canada either has Varroa mites today or will have them within several months. Varroa mite infestation represents one of the greatest threats to honey bee health, honey production, and pollination services. When honey bee colonies are untreated or treated ineffectively colonies can fail and beekeepers can incur major economic losses, and, ultimately, agricultural food production may be impacted. In addition, colonies with Varroa are a source of mites that can spread to other colonies, even in other apiaries, through drifting, robbing, and absconding activity of bees. All beekeepers should remain vigilant to detect high Varroa mite levels and be prepared to take timely action in order to reduce mite loads. Effective mite control will reduce colony losses and avoid potential spread of infectious disease among colonies. This Guide will explain practical, effective methods that beekeepers can use to measure Varroa mite infestations in their hives and select appropriate control methods. The Honey Bee Health Coalition offers this Guide free of charge and asks that you please reference the Coalition if distributing. Tools for Varroa Management | Page 3 DESCRIBING VARROA MITE LEVELS The most accurate way to describe Varroa mite infestation is the number of mites per 100 adult bees. For brevity, this Guide expresses mite levels as a percentage. For example: “3 mites per 100 adult bees” is written as “3 percent” in this Guide. PHOTO COURTESY OF THE BEE INFORMED PARTNERSHIP Integrated Pest Management This Guide presents information There is no “one-size-fits- and Varroa Mite Control about IPM techniques that all” solution for Varroa integrate: management. This Guide The information presented in this also reviews the efficacy, Guide will best help beekeepers » Rigorous monitoring of application, advantages, who recognize that optimum mite populations to detect and disadvantages of a wide management of Varroa is increases in the number of variety of control methods. This based on understanding: mites early and to assess the effectiveness of controls. allows beekeepers to choose » The life cycles of both the an approach suited to their honey bee colony and the » Use of cultural practices (i.e., individual circumstances and mite. breeding, screen bottom risk tolerance. board, removal of drone » The number of mites present brood, etc.) to deter mite Doing nothing about Varroa in the colony at any point in population build-up. mites is not a practical option time. » Rotation of chemical for most beekeepers. Honey » How tactics to control mites products that considers bees are not capable of vary according to the season mite/bee population surviving or thriving unless the and type of beekeeping dynamics and minimizes beekeeper prevents Varroa operation. potential development of from reaching damaging levels. If the beekeeper does Successful Varroa control mite resistance caused by not control Varroa, a colony solutions are proactive. They repeated use of any one will most likely die and, in the control Varroa before the mites chemical control. process, spread mites and reach levels that threaten IPM techniques can help infections to other colonies colony productivity and survival, beekeepers maintain a colony’s in the same apiary and rather than respond after Varroa mite levels below 2 to 5 surrounding area. the damage has occurred. mites per 100 adult bees (i.e., a Integrated Pest Management 2 to 5 percent infestation level). (IPM) is a set of proactive, Current data suggest that using non-chemical and chemical these treatment thresholds methods that offers beekeepers may be a successful strategy the best whole systems for decreasing overall colony approach to controlling Varroa. losses. Tools for Varroa Management | Page 4 ABOUT VARROA MITES remain and mite populations Varroa mite populations can increase quickly and increase and decrease in unexpectedly. As a rule of synchrony with the seasonal thumb, in colonies with brood, pattern of honey bee mite populations double about development. Mite populations once a month -- and even reach their highest levels soon quicker when the colony has after the brood and adult large amounts of drone brood, honey bee populations reach or when Varroa are transmitted their peak, when there are more PHOTO COURTESY OF THE BEE INFORMED PARTNERSHIP from neighboring colonies. brood bees on which Varroa The Varroa mite, Varroa Therefore, beekeepers should reproduce. When the bee destructor, is a parasite that lives have an IPM plan in place to population and the amount of on the outside of its host. The frequently and regularly monitor bee brood decline, the phoretic mite feeds on the brood and and manage Varroa mites in mite numbers drastically adults of western (European) their colonies. increase on the adult bees honey bees, Apis mellifera. as the amount of bee brood When left untreated, colonies Honey Bee and Varroa Mite decreases. Eventually, Varroa with high levels of Varroa may Seasonal Development numbers decrease, along with die within months. Varroa mites Honey bees and their Varroa the adult bee population. The reduce overall colony vigor as mite parasites cycle through size of the mite population at well as transmit and enhance four temporal phases. In some the start of Population Decrease diseases, such as honey bee locations, there is one cycle per is critical because the colony viruses. Varroa, which is present year and, in other locations, needs to be healthy enough to on all continents, except more than one cycle. The rear sufficient numbers of bees Australia and Antarctica, is the phases are: to survive the dormant phase. most damaging honey bee pest During broodless periods, all » Dormant and a major factor responsible mites are carried on adult bees, for colony losses worldwide. » Population Increase except in locations where » Population Peak reduced brood rearing may be Adult Varroa mites are phoretic continuous during this phase » Population Decrease – they move around the (see Figure 1). environment by attaching themselves to adult bees. They Figure 1: Honey Bee & Varroa Mite Seasonal Phases readily spread among colonies Population Peak and apiaries through natural drift of workers and drones, robbing of weak colonies by stronger ones, swarming, and absconding, or through human- Population Population aided exchange of bees Increase Decrease and brood frames between colonies. Mites do not live longer than a few days without Dormant their host; so unoccupied bee Dormant equipment does not harbor live Population Size mites. Phase Bee Population Mite Population Even after a colony has For details on the Varroa Life Cycle consult: been treated, Varroa mites www.extension.org/pages/65450/varroa-mite-reproductive-biology Tools for Varroa Management | Page 5 MONITORING VARROA Recommended Sampling Equipment Needed: MITE POPULATIONS Methods » Wide mouth jar, such as quart Bee