Comparison of the Efficacy of Mite-resistance Assays in Predicting Resistance Trait Heritability, Colony Mite Loads, and Overwinter Colony Survival

Commodities

• Animals: bees

Practices

• Animal Production: animal protection and health, livestock breeding
• Education and Training: workshop
• Pest Management: genetic resistance

Honey bee health underpins more than $20 billion in annual U.S. crop pollination. However, rising colony losses driven largely by Varroa destructor, viruses they transmit and rising miticide resistance threaten both farm viability and food security. In 2025 national honey bee losses exceeded 60% in commercial beekeeping operations. Miticide resistance was discovered in 100% of tested samples, highlighting an urgent need for biology-based strategies that reduce chemical dependence while strengthening colony resilience.

This project evaluates the reliability and heritability of four major hygienic behavior assays, in order to determine which methods best predict mite resistance and overwinter survival. We will compare assay performance in twelve breeder colonies (six selected, six controls) and their untreated F1 daughters. Across two seasons, all colonies will undergo standardized rounds of UBO, PKB, and FKB testing, as well as mite washes and Harbo assays. By analyzing correlations among assay scores, mite loads, reproductive mite presence, and overwinter survival, we will identify which tools reliably capture heritable Varroa-resistant traits and which factors influence assay consistency.

This project addresses a documented need for effective selection tools that help beekeepers identify and propagate Varroa-resistant stock. Results will be shared through a report, digital outreach, and a presentation at Cornell's Dyce Lab. A hands-on workshop at They Keep Bees will train beekeepers to practice each assay method. By providing evidence-based guidance to at least 100 beekeepers, the project aims to enable measurable improvements such as higher overwinter survival and reduced reliance on miticides.

Primary Research Questions

1. Do pin-killed brood (PKB), freeze-killed brood using liquid nitrogen (FKB), and unhealthy brood odor (UBO) assays provide predictive measures of heritable mite-resistant traits in F1 daughter queens?
   
   
2. Are these assays also predictive of overall colony mite loads and winter survival outcomes? Winter survival will be defined as survival from August of year 1 until March of year 2.
   
   

Measurable Objectives

• Objective 1

Quantify hygienic behavior in breeder queen and control colonies using PKB, FKB, and UBO assays, scoring each hive according to standardized protocols to determine levels of Varroa resistant hygienic behavior.

• Objective 2

Measure reproductive Varroa mite levels and phoretic mite loads in breeder and control colonies using Harbo Brood assays (HB) and alcohol washes, scoring colonies according to standardized HB and mite-wash methodologies.

• Objective 3

Quantify hygienic behavior in F1 daughter colonies (from both breeder queens and controls) using PKB, FKB, and UBO assays, and score each colony using the same standardized protocols applied to mother colonies.

• Objective 4

Analyze correlations among PKB, FKB, UBO, HB, and mite-wash results across all breeder and F1 colonies, and determine whether these assay outcomes predict colony-level mite loads, trait differences between selected vs. control lines, and winter survival rates. Winter survival will be defined as survival from August of year 1 until March of year 2.

• Objective 5

Perform outreach to 100 beekeepers through post-trial educational workshops, presentations and publish a report of the findings with clear statistical analysis.