Performing Department
(N/A)
Non Technical Summary
There are many stressors contributing to poor health in honey bee colonies that are used for pollination of almonds, apples, blueberries, pumpkins and many other healthy foods. However, the varroa mite, a devastating parasite of honey bees, is consistently identified as the most serious threat to honey bees. Many commercial beekeepers providing hives for crop pollination are struggling to manage varroa as this pest has evolved resistance to common control methods. Despite the challenges, some beekeepers have been successful at using a range of genetic, cultural and chemical varroa control tactics in an Integrated Pest Management approach. Widespread adoption of these practices across commercial beekeeping has been limited by barriers to communication driven by a lack of objective data on the efficacy and timing of varroa control methods and an accounting of the economic costs. Even among beekeepers that are successfully managing varroa today, new approaches for varroa control are badly needed to handle future varroa outbreaks.To reduce honey bee colony losses and maximize the strength of colonies available for crop pollination beekeepers need (1) a re-evaluation of the efficacy and economics of using various combinations of currently available varroa management tools, (2) development of new chemical controls that overcome resistance, and (3) integration and implementation of all approaches into comprehensive varroa management plans.
Animal Health Component
60%
Research Effort Categories
Basic
20%
Applied
60%
Developmental
20%
Goals / Objectives
The sustainability of the pollination-dependent U.S. specialty crop industry, including almonds, blueberries, cranberries, strawberries, apples, cucurbits, melons, vegetable seed and others, depends on a predictable and healthy supply of honey bee colonies. Beekeepers must effectively manage parasitic varroa mite populations to maintain a sufficient number of strong healthy colonies to meet pollination needs. Beekeepers will be required to change the way mites are managed due to growing resistance to widely used miticides. This can be accomplished through a trans-disciplinary approach working with beekeepers to (1) Identify and disseminate cost-effective approaches to mite management using currently available methods and (2) Developing new chemical varroa controls, with new modes of action, combined with optimized use of existing chemical tools, to manage varroa resistance and integrate with existing mite management programs.Social Science Research Objective: A: Identify varroa management programs implemented by beekeepers leading to reduced colony loss, and evaluate beekeeper information-seeking behavior and motivations when managing for varroa.Hypotheses:(1) Common elements of varroa control programs that are related to reduced colony losses will be identified through structured interviews with beekeepers and field testing of management efficacy and varroa resistance(2) Common elements of beekeeper learning and decision-making processes related to varroa control, including economic constraints and source of management guidance, will be identified.Natural Science Research Objective:B: Determine prevalence and mechanisms of varroa resistance to miticides and develop novel resistance-breaking tools for effectively controlling varroa mites in honey bee colonies.Hypotheses:(1) Miticide resistance monitoring will establish that currently registered miticides have reduced effectiveness at controlling varroa populations,(2) Existing pesticides with current registration for other uses and natural products will be safe and effective against varroa resistant to existing miticides and can be formulated for varroa control(3) Efficacy of oxalic acid, a currently registered miticide with no known varroa resistance, can be maximized through improved timing and delivery.Outreach Objective:C: Disseminate best practices for varroa IPM that are cost effective and overcome identified barriers to adoption and reduce colony losses.Hypothesis:Beekeepers will exhibit behavior change and adopt IPM-based varroa control programs if they are demonstrated to be (1) effective at reducing colony losses, (2) economically reasonable, (3) presented by trusted beekeepers or through other trusted sources, and (4) can be tailored to their specific needs.
Project Methods
Social Science EffortsOnline and in-person surveys: Surveys will be conducted at national and regional beekeeping conferences using to explore information-seeking behavior among beekeepers, to assess commonly employed varroa management techniques and to assess the decision making process beekeepers practice concerning varroa management. Semi-structured interviews will be conducted with large-scale beekeepers to gather information on the same topics, but with additional questions . Human ethics (IRB) approval will be obtained by the appropriate institutions before conducting any research with participants.Cost-return studies: Economic costs of the various varroa control methods will be separated into operating and investment costs. Economic benefits from varroa management strategies will be measured in terms of decreased colony mortality at points throughout the year. Lower colony loss rates depending on time of year will result in higher pollination income or honey production. Economic benefits will also be measured for almond producers. Decreased colony mortality will lead to lower risk of inadequate pollination, which should lead to decreasing pollination fees over time. Additionally, growers optimize the number of hives per acre and colony strength to save on input costs. These benefits will be quantified using pollination fee estimatesalong with colony strength and mortality measurements.Natural Science EffortsDirect assessment of colony health: On-the-ground follow ups with beekeepers participating in the semi-structured interviews will directly assess colony health, varroa infestation levels and resistance to current miticides will be conducted. A standard inspection will be conducted in spring, while colonies are pollinating almonds, and in fall, when varroa infestations peak. Canonical correlation analysis will be used to associate monitoring and management practices to a series of beekeepers determinants using CCA. Mortality data will be modeled using a mixed effect GLMM to estimate the relative risk of practices while accounting for confounding factors such as operation size, migratory status and region.Resistance monitoring assays: This cage bioassay method measures the number of varroa dislodged from bees when exposed to a small strip of Apivar® (amitraz) in a 1-quart plastic container to assess amitraz resistance. Resistance monitoring tests will be conducted with the same beekeepers in multiple years so that changes in amitraz resistance levels can be documented over time.Miticide use patterns: A 10-gram sample of wax from the center of 2 brood combs in colonies in each of 25 apiaries will be collected from colonies subject to resistance monitoring assays. Wax samples will be pooled at the apiary level and miticide concentrations will be determined by GC-MS or LC-MS at the USDA-AMS laboratory in Gastonia NC. Miticide use patterns will be paired to results of resistance testing and miticide concentrations in wax to determine mite control methods associated with the development of resistance.Screening novel miticides: Potential miticide compounds will be screened for varroa toxicity and bee safety first by generating separate dose-response curves using vial bioassays. A decision tree will be used to evaluate results and promote promising compounds to cage testing wher the number of varroa that fall through the mesh flooring of the cages during the 48 hour trial will be counted and removed then the bees will be subjected to an alcohol wash to remove remaining varroa. Survivorship data will be analyzed using binomial-logit generalized linear mixed-effects models (GLMMs) to establish dose-mortality curves.Field testing varroacide formulations: Mini-nucleus colonies will be prepared for testing 3 concentrations/product. Each concentration will have 3 replicates (2 modified brood boxes). A negative control and positive control will be included. The efficacy of mite-kill (%) will be calculated based on comparing the infestation percentage at day 15 and day 28 to the percentage of infestation at day 0. Data will be analyzed using a mixed model ANOVA. This preliminary analysis will then inform the concentration or dosage of formulations taken to full field trials.For each field trial colony assessments and varroa population estimates will be made before initiation of the trial, at the end, and at least two times while the miticide application is present. Analysis of all field data will utilize a GLMM-framework. At least 10 g of honey and wax will each be collected from 5 randomly selected colonies in the treatment and control groups for pesticide residue testing at the USDA-AMS lab in Gastonia, NC.Optimization of oxalic acid as a miticide: Field trial involving full-sized colonies will test temperature of oxalic acid vaporization (160°C, 180°C, 210°C, and 230°C), seasonal differences in oxalic acid efficacy, and five different common application methods used by beekeepers to apply OA to their colonies. Varroa infestation and colony strength parameters will be measured.Outreach effortsDemonstration trials: Three demonstration trials will be performed by Bee Informed Partnership Tech Team Specialists using beekeeper-managed colonies. Standard colony health data will be collected, including varroa levels by alcohol wash. One treatment group will serve as a positive control, managed according to the participating beekeeper's standard varroa management scheme and compare with demonstrated successful practices identified through the work of the project, either existing methods proven successful by beekeepers or novel miticides will be used. Bee Informed Partnership Tech Teams will monitor colonies prior to specialty crop pollination events.Case studies: Narrative case studies will be developed using information initially collected through semi-structured interviews, decision making assessment, and on-the-ground follow-ups above. Beekeeper permission to be included in publicly available case studies will be sought, and additional documentation of IPM treatment regimes by the beekeepers will be established. Cost analysis of varroa control will be included.Varroa Management Decision Support Tools and Resources: The Varroa Decision Support Tool will be adapted for large-scale beekeepers by expanding the decision criteria to include the treatment windows based on their business model and the cost and return information. The tool will be presented in the form of an interactive Excel spreadsheet that will allow beekeepers to input information corresponding to the specifics of their operation and to make decisions.Evaluation:Major Indicators(1) Number of beekeepers reached(2)Number of novel miticides identified(3)Number of existing successful tools identified(4)Increase in knowledge & intention to change behavior(5)Adoption of recommended best practices(6)Decrease in varroa parasitism and increase in honey bee colony healthEvidence for(1)Beekeeper support, new stakeholders(2)Successful decision tool and varroa miticide pipeline(3)Successful cooperation with stakeholders(4)Access to effectively communicated information appropriate for real-world scenarios(5)Use of information, or immediate corrective action after pest management recommendation(6)Adequate training programsEvaluation type(1)Quantitative(2)Quantitative(3)Quantitative / qualitative(4)Quantitative(5)Quantitative / qualitative(6)Quantitative / qualitativeEvaluation Methods(1)Analytics for website hits and Podcast listens, submitted questionnaires(2)Lab and field trial data(3)Interviews, Demonstration Trial data, BIP Tech Team colony health/productivity monitoring(4)Pre-/post- questionnaires, interviews, BIP Survey(5)Pre-/post- questionnaires, interviews, BIP Survey(6)Pre-/post- questionnaires, interviews, BIP Tech Team health/productivity monitoring, BIP Survey