Field Validation of Practical Mite Resistance Tests Across Apiaries To Strengthen Small-Scale Breeder Selection

Commodities

Practices

The core problem this project aims to solve is that beekeepers still lack practical, reliable, field-ready tools to identify true Varroa-resistant colonies. Although decades of research show that resistance traits like suppressed mite reproduction and hygienic behavior exist, most small-scale and sideline beekeepers do not have accessible methods to measure them. As a result, breeding decisions are often based on survivorship, gut instinct, or single metrics like low mite washes none of which reliably indicate heritable resistance. The simplified Harbo assay, PKB test, and mite washes each capture part of the picture, but my own multi-year data has shown inconsistent results when these tools are used without standardization across yards, equipment, colony age, and sampling timing.

This inconsistency means beekeepers often misidentify breeder colonies, accidentally propagate weak genetics, or treat more than necessary, masking the very traits we need. At the same time, commercial operations report that resistant stock is hard to find, and current supply cannot meet demand. Without a validated, repeatable screening process that small producers can actually perform, the pipeline of trustworthy resistant queens will never develop. This project addresses that gap by testing, comparing, and stabilizing these field tools so beekeepers can finally select with confidence.

My innovative solution is to create a simple, field-ready system that allows beekeepers to identify truly Varroa-resistant colonies using tools they can perform in their own apiaries. Instead of relying on survivorship guesses or single metrics, this project tests three practical resistance indicators the Simplified Harbo Assay (SHA), the Pin-Killed Brood assay (PKB), and standardized mite washes under real working conditions to determine which combination of methods reliably identifies colonies that maintain low mite levels over time. The goal is not to invent new lab techniques, but to validate and refine accessible field tools until they form a consistent, repeatable screening protocol for small-scale breeders.

The study uses two beekeepers, each managing 20 standardized colonies for a total of 40 research colonies. Every colony is started on identical equipment, equalized as needed, and managed through the same treatment thresholds to keep environmental variables as controlled as possible. Each year, every colony receives:

• Two SHA tests to measure suppressed mite reproduction (NR:R ratios),

• Two PKB assays to assess hygienic response, and

• Four mite washes to track Varroa population growth through the season.

This creates a multi-layered dataset that shows how each test behaves not just once, but repeatedly, across differing colony strengths, nectar flows, and environmental stress. The innovative piece is the integration: instead of evaluating SHA, PKB, and mite washes in isolation, we directly test how well they agree, which signals are most stable over time, and which early-season measurements predict late-season mite control. That allows us to build a practical "selection filter" that breeders can use without expensive equipment, specialized training, or complicated statistics.

To deepen the biological context, a subset of colonies each year undergo viral testing (DWV-A, DWV-B, ABPV, CBPV). This shows whether colonies flagged as resistant by SHA/PKB/mite-wash profiles also maintain lower viral loads. This adds rigor and helps ensure that the scoring system we produce isn't only measuring low mites, but genuine tolerance or resistance traits.

The regenerative agriculture component lies in reducing chemical dependency. If beekeepers can reliably identify resistant colonies, they can select and propagate queens that require fewer treatments or none at all. This reduces pesticide residues in comb, prevents chemical resistance in mites, improves colony longevity, and strengthens local adaptation. Instead of relying on continual chemical inputs, the system shifts toward biological resilience and locally selected genetics, which aligns directly with regenerative agriculture principles.

The project also includes a strong educational component. Each year, the participating beekeepers refine the testing protocol based on field experience. Results are shared through the Sustainable Beekeepers Guild of Michigan (SBGMI) and Northern Queen Initiative (NQI) via webinars, field days, and plain-language summaries. The teaching emphasizes hands-on demonstration, showing beekeepers exactly how to perform each assay, how to interpret results, and how to apply the protocol to their own stock.

The innovation is not a new test, it is creating the first practical, validated, field-ready resistance-screening system that small producers can trust, replicate, and use to build healthier, chemical-independent bees.

Objectives Include:

• Standardize and manage 40 research colonies across two apiaries to create a controlled testing environment.

• Perform repeat, multi-season SHA, PKB, and mite-wash assays to evaluate how consistently each test identifies resistant colonies.

• Compare agreement between the tests and determine which early-season measures best predict late-season mite control.

• Conduct targeted viral testing to connect resistance indicators with actual colony health.

• Produce a simple, field-ready screening protocol that small-scale beekeepers can use to confidently select breeder colonies.

• Share results through SBGMI and NQI workshops, webinars, and written summaries.