Bridging Breeds; Enhancing Carniolan Bees with Varroa Sensitive Hygiene Traits via Instrumental Insemination

Commodities

Practices

Carniolan honey bees are renowned for their gentleness, productivity, and winter hardiness, making them a popular choice for beekeepers worldwide. However, this population continues to suffer from varroa-related challenges, including colony losses, diseases, and weakened hive performance. Despite their widespread commercial use, little significant work has been undertaken to select for VSH traits within the Carniolan bee population, which are critical for varroa mite resistance and the sustainability of the subspecies as a whole.  Additionally, there is considerable market demand for VSH Carniolan bees, and supply is not being met within the industry.

Solution and Objectives:

This project addresses the lack of varroa sensitive hygiene (VSH) traits within the Carniolan honey bee population. By working together, we aim to narrow this gap by both selecting for existing VSH traits within the Carniolan population in Megan’s operation, and integrating higher-level VSH traits with drone semen and virgin queen introductions from Cory’s operation. This will improve the overall health and sustainability of Carniolan honey bees, furnish a robust model for future breeding exchanges, and provide beekeepers with an option for obtaining VSH Carniolan stock.  

Megan is currently treating her population for varroa mites at least 4 times annually, Cory is applying zero treatments.

Objective 1: Identify the Best Stock to Propagate Queens (graft) From

The first step involves identifying the most promising colonies within each of our existing breeding operations. Using performance metrics, including colony health, temperament, productivity, color and VSH scores, we will select the highest-quality colonies for grafting in the springtime. See attached  Colony Performance Rubrics.  Once identified, Megan and Cory will each share 30 virgin queens per year with one another, ensuring a diverse exchange of Carniolan and VSH genetics between operations. Queens will be shipped via UPS overnight shipping.

Objective 2: Instrumental Insemination of Virgin Queens

The virgin queens will be inseminated with selected drone semen to initiate crossbreeding between the Carniolan and VSH populations:

Megan's Virgins: These will be inseminated with the high-scoring VSH drones, that also express some Carniolan characteristics (gentleness, productivity, black in color) from Cory’s population. This strategy prioritizes the integration of high-level VSH traits into the Carniolan line while maintaining the unique grey-black color characteristic of Carniolan bees.

Cory's Virgins:  Virgins exhibiting the most Carniolan-like traits from Cory’s VSH stock will be inseminated with semen from Megan’s Carniolan breeding population, ensuring the genetic integrity of the Carniolan line while introducing enhanced VSH traits.

This targeted insemination plan of action will help to ensure the genetic diversity of the queens while minimizing the risk of inbreeding.

Objective 3: Establish Colonies with Newly Inseminated Queens

The inseminated queens will be introduced into hives to establish new colonies. These colonies will be monitored to evaluate their viability over time and to ensure the original queens are still present.

Objective 4: Performance Tracking and VSH Testing

Acceptable colonies will undergo performance evaluation, including:

Productivity Metrics: Temperament, colony strength/build up, color, and disease prevalence will be monitored to ensure desirable Carniolan traits are retained.

VSH Testing (Harbo Assay): This testing will measure the degree of mite resistance by observing the colonies’ ability to identify and remove reproductively viable Varroa-infested brood. Cory will conduct Harbo assays on his colonies in early fall, while Megan will conduct testing on hers in early Spring.  Each cooperator will travel to the other’s operation during this time period to assist in the testing and scoring process.  Refer to attached rubrics for evaluation metrics.

Objective 5: Selection for 2026 Breeding Season

Based on the performance tracking and VSH test results, the highest-scoring colonies will be selected for grafting in the 2026 season. We will repeat this process for the 2026 breeding cycle, hopefully starting with a higher level of VSH than the previous year.

Objective 6: Outreach

Share findings and breeding protocols throughout the bee industry at in-person conferences, on social media, YouTube, and other meeting forums.

Goal: Augmenting the Carniolan Population with VSH Traits at the Population Level

By continually selecting for high-performing colonies in addition to measuring VSH scores, this project seeks to establish a population of Carniolan honey bees that are better equipped to thrive in the presence of Varroa mites.