Sustainable parasitic mite control for honeybees
Varroa mite infestations have decreased honey production and pollination, and the project manager will offer education on integrated pest management techniques to beekeepers, especially those on the brink of abandoning their honey operations. The design and development of at least two IPM tactics will be accompanied by varroa control and monitoring and workshops for farmers; the goal is to have 100 beekeepers implement IPM controls and 500 to 1000 begin or improve varroa monitoring.
Two changes in beekeeper behavior are targeted: 1) 500-1000 beekeepers will be monitoring varroa levels to determine if a threshold has been exceeded prior to treating the colony with a miticide and 2) 100 beekeepers will have implement at least two IPM tactics to control varroa.
This project targets 300 of the approximately 5000 hobbyists and 700 sideliners in MAAREC to participate in planning workshops. From the 300 beekeepers, 10 beekeepers will participate in the evaluation of IPM tactics plus mite monitoring. Each of the beekeepers will hold, with our assistance, a workshop at his/her apiary to demonstrate IPM tactics and monitoring. Fifty beekeepers will attend each apiary workshops (400-500 total) and 40-80 will implement multiple IPM tactics to control varroa during the second year.
Few beekeepers currently monitor for varroa and IPM cannot be implemented effectively without monitoring; we will encourage beekeepers to begin monitoring for varroa. Approximately 200 beekeepers each year will be recruited to begin monitoring.
Beekeepers will be able to reduce their use of fluvalinate and coumaphos, and the resulting residues in hive products, by at least 50%, reduce the cost of production by decreasing the annual colony mortality from 40-60% to less than 20% and supply healthy bees for honey production and pollinating field crops and wild plants.
We will verify reaching our target through surveys and data from state apiary inspection programs. To provide a baseline from which to measure behavior change, specific information will be collected about varroa control IPM tactics used by beekeepers and the success of those tactics prior to the start of the project from approximately 2000 hobbyist and sideline beekeepers. Annual surveys will be conducted to evaluate progress toward adoption of IPM control tactics and monitoring of varroa levels. Additionally, we will obtain the annual statistics of the beekeeping industry from each MAAREC state to verify changes in management practices.
A survey is under development to assess the baseline status of varroa monitoring and use of IPM tactics in the Mid-Atlantic region. The survey is expected to be complete by mid-January and mailed to most of the region’s beekeepers by early February.
At this time we have 16 beekeepers participating in six varroa control and monitoring studies. One beekeeper with approximately 350 hives is interested in determining the distribution of mites within an apiary along with determining any differences in the reliability of monitoring methods. This beekeeper is also interested in the interaction of virus and varroa as it relates to over wintering survival and if the timing of interventions to reduce mite levels alters the efficacy of the intervention. A group of 4 beekeepers are interested testing the fall mite threshold and determining overwintering success at these thresholds. Three beekeepers are cooperating to test formic acid as a control tactic for varroa and another beekeeper is testing oxalic acid. Five beekeepers are preparing to test sucrose octanate in colonies. This material is registered for use in honey bee colonies to control varroa but application methods have not been developed. To date the only method tested is the spraying of each individual frame of bees (10 frames, 2 sides each, per hive box). This method is too time consuming for all but the smallest of beekeepers (1-2 hives). These five beekeepers are testing application methods they believe will reduce the time for application but result in similar dose levels. The last study by two beekeepers is looking at varroa population growth rates and the potential for stopping monthly monitoring if varroa levels remain low during the summer. Additionally, thirteen beekeepers are planning projects to begin in spring 2004. Based upon the response thus far, it is expected that more beekeepers will wish to conduct experiments as part of this project. We will encourage beekeepers to work together in order to improve the quality of the experiments. We will also encourage beekeepers to adopt IPM tactics and test the efficacy of the tactic on their own. The number of IPM workshops planned for the spring and summer will remain the same.
Forty-eight beekeepers have been recruited to begin monitoring for varroa in June 2004. Announcements for recruiting more beekeepers have been sent to state and local beekeeping associations for insertion into newsletters. A regional announcement on the MAAREC web site is planned. More beekeepers will be recruited during the next 4 months at various state and county beekeeper meetings, through newsletter announcements and direct contact by apiary inspectors and study personnel. Because of the late start of the project – mid-June 2003 – we were unable to provide beekeepers with monitoring tools early enough in the year to provide meaningful data. Sticky boards, to provide beekeepers with an incentive to monitor, have been ordered. Because of the delay in data collection we plan to continue recruiting beekeepers to implement monitoring through the 2005 season.
The target for the number of beekeepers participating in studies (10) has been exceeded. Workshops are being planned at several apiaries and we expect to have 20 beekeepers participating in studies by next summer (2004). We have recruited beekeepers for monitoring for varroa, Several beekeepers monitored during summer 2003 and we expect to meet our target of 200 beekeepers. Workshops demonstrating varroa monitoring using powdered sugar shakes are planned for spring 2004. Data for all these projects are being collected and analysis will begin on some projects by mid-spring 2004.
Impacts and Contributions/Outcomes
No results of the baseline survey are available at this time. Raw data are expected to arrive by March/April 2004 and analysis will be begin at that time.
The study determining the distribution of mites within an apiary has produce preliminary data that we will be testing against other data. Thus far the data indicate that colonies in the northwest corner of an apiary have the highest mite levels. If this result can be verified with other data collected over the last 4 years, then we will be able to test the reliability of decisions made using this information in apiaries with 20 or more colonies. If it is possible to predict the distribution of mites in an apiary the time a beekeeper needs to spend monitoring his/her colonies will be reduced.
We have also been able to obtain preliminary information on the reliability of powdered sugar shakes for monitoring varroa. As long as the beekeeper calibrates the number of bees obtained in a sample, we are able to reliably predict colony mite load.
A group of beekeepers (4) wanted to test the survivorship of overwintered colonies using the fall mite thresholds. This work would result in the reduced application of miticides as approximately half the hives did not need to be treated. Each beekeeper was asked questions about how adverse he/she was to losing colonies and about their willingness/reluctance to use miticides. [This was to help the beekeeper determine the level of risk that was acceptable.] Colonies with mite levels substantially below the threshold were not treated. Colonies with mite levels substantially above the threshold were treated. Colonies with mite levels between the two extremes were treated or not depending upon the beekeepers risk assessment. Survivorship of all colonies will be recorded in February (winter survivorship) and April (sufficient honey stores to last until nectar and pollen flow begins). Preliminary data indicate that the timing of the decision to treat or not treat is crucial. If one treats for varroa too late in the year, and viruses are present in the colony, the colony has a very high chance of dying even though mite levels are low after treatment. The beekeepers are very important to our ability to determine if treatment timing is a component of colony survivorship because of the number of colonies that can be studied.
Three beekeepers are testing formic acid in a 1 or 2 day treatment. Thus far we have observed significant loss of mites from treated colonies and, at the higher formic acid doses, queen loss. Normally queen loss would be a sufficient reason to drop this control tactic but a number of beekeepers, including two conducting this work, are interested in using formic acid to remove the queen when requeening is desired, while at the same time reduce mite levels. Using formic acid to remove a queen would eliminate the very time consuming and difficult task of finding and removing the queen when the queen needs to be replaced. One of the beekeepers also noticed that Small Hive Beetles left the colony when formic acid was applied.
University of Delaware
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Newark, DE 19716
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