DOI: 10.5061/dryad.v6wwpzh6p
title: Bees bred for Varroa sensitive hygiene trait demonstrate resistance to chalkbrood disease

description: To improve health and vitality of honey bees, Apis mellifera, beekeepers
 can propagate stocks that demonstrate resistance to both parasites and
 pathogens. Most breeding programs focus on resistance to Varroa destructor
 mites and/or brood pathogens. Colonies bred specifically the trait Varroa
 Sensitive Hygiene (VSH) have never been explicitly tested for resistance
 to brood disease. The goal of this study was to test if colonies bred for
 VSH are both mite and disease resistance. Over two years (2023 and 2024)
 and in two locations (University of Minnesota and the USDA-ARS lab in
 Baton Rouge, Louisiana), we compared colonies from the POL line bred
 specifically for Varroa resistance to colonies from a commercial source
 that were not selected specifically for Varroa resistance but were
 selected for “general” hygienic behavior using the freeze-killed brood
 (FKB) assay. We challenged colonies within each line with Ascosphara apis,
 that causes chalkbrood, and quantified mites, disease and hygienic
 behavior. Our study demonstrated that colonies from the POL line bred for
 VSH are just as resistant to chalkbrood as bees from a Commercial line
 bred for hygienic behavior by the FKB assay. Results confirmed that the
 POL line is more mite resistant than the Commercial, as it had
 significantly lower mites in two of three trials. Both the POL and
 Commercial colonies had high levels of hygienic behavior as measured by
 the FKB assay. These results indicate that honey bees selected for VSH
 respond to both mite-infested and disease-infected brood. Further
 comparative studies are needed to clarify any differences in genetic
 mechanisms and olfactory sensitivity mediating the VSH-trait and general
 hygienic behavior. On a practical level, using lines of honey bees
 selected for VSH in beekeeping operations could help curb losses, improve
 honey bee health, and reduce financial burdens caused by Varroa and
 diseases.
description: # Bees bred for Varroa sensitive hygiene trait demonstrate resistance to
 chalkbrood disease Dataset DOI:
 [10.5061/dryad.v6wwpzh6p](10.5061/dryad.v6wwpzh6p) ## Description of the
 data and file structure R script, and CSV files used to investigate
 chalkbrood resistance, mite resistance, and hygienic behavior in two lines
 of bees (a mite-resistant line and a line bred for general hygienic
 behavior) in Minnesota (2023 and 2024) and Louisiana, USA (2024). These
 data are associated with a manuscript that is currently under review. The
 data set contains four CSV files:  1. from Minnesota 2023
 (Carver2023RStudio) 2. from Minnesota 2024 (Carver2024) 3. compilation of
 the two datasets from Minnesota over the two years (Carver23_24) 4. and
 from the experiment in Louisiana 2024 (BTRData24) All csv files are coded
 to load into the ManuscriptCode file. This file contains all the code used
 to compare chalkbrood score, mite loads, colony strength, and hygienic
 behavior between the two queen lines. As well as code for all
 visualizations.  ### Files and variables #### File:
 ManuscriptCode4.15.25.rmd **Description:** This is the R markdown file
 that loads all the CSV files used and the code used for all statistical
 tests and visualizations in the manuscript.   #### File: Carver23\_24.csv
 **Description:** This is data from Minnesota 2024 and 2023 in one file for
 metric comparison between the years. Cells that are blank (missing values)
 or containing NA values indicate that data was unable to be collected for
 that metric measured.   ##### Variables * Stand:: Stand ID number *
 Colonynumb: Colony ID number  * Queen: Queen line (P = Pol line or C =
 Commercial line)  * Year: 2023 or 2024 (year of study)  * pre_mites:
 mites/100 adult bees pre-challenge * post_mites: mites/100 adult bees
 post-challenge * Fr_Bees: Frames of bees counted pre-challenge * Fr_Brood:
 Frames of brood counted pre-challenge * Br_Pt: Brood pattern (scored 1-5)
 pre-challenge * Strict_FKB: Percent of freeze killed brood removed in 24
 hours * week1_CB: Chalkbrood severity score at 1 week post-challenge *
 week2_CB: Chalkbrood severity score at 2 weeks post-challenge #### File:
 BTRData24.csv **Description:**  Data from study replication done in Baton
 Rouge, LA, in 2024 ##### Variables * Colony: Colony ID number * Queen:
 Queen line (It = Commercial, P = Pol-line) * peak: Peak infection
 (combination of early signs and mummies at 4 days post challenge) *
 7.15_chalk: Chalkbrood severity at 1 week * 7.15_brood: Brood area at 1
 week * 7.12_chalk: Chalkbrood severity at 4 days * 7.12_brood: Brood area
 at 4 days  * 7.10_chalk: Chalkbrood severity at 2 days * 7.10_brood: Brood
 area at 2 days * Strict_FKB: Strict percent of FKB removed in 24 hours *
 Liberal_FKB: Liberal percent of FKB removed in 24 hours  * june_mites:
 Mites/100 adult bees pre-challenge * 7.10_early_zeros: Early sign severity
 at 2 days post-challenge * 7.12_early_zeros: Early sign severity at 4 days
 post-challenge * 7.15_melty: Early sign severity at 1 week post-challenge
 #### File: Carver2024.csv **Description:**  Data from study in Minnesota
 2024. Cells that are blank (missing values) or containing NA values
 indicate that data was unable to be collected for that metric measured.  
 ##### Variables * Stand:: Stand ID * Colony #:: Colony ID * Queen: Queen
 line (P = Pol-line, C = Commercial line) * Peak: Peak infection
 (combination of early sign and mummy severity at 1 week post challenge) *
 may_mites: Initial mites/100 adult bees (this was the mite load right
 after we re-queened to see if the packages we made up needed to be
 treated) * june_mites: Mites/100 adult bees pre-challenge * aug_mites:
 Mites/100 adult bees post-challenge * Fr_Bees: Frames of bees
 pre-challenge * Fr_Brood: Frames of brood pre-challenge * Br_Pt: Brood
 pattern pre-challenge (ranked 1-5) * Fr_BeesAug: Frames of bees
 post-challenge * Liberal_FKB: Percent of FKB removed in 24 hours
 (liberal)  * Strict_FKB: Percent of FKB removed in 24 hours (strict)  *
 6.29_CB: Chalkbrood severity at 4 days * 6.29_brood: Brood area at 4 days
 * 7.1_CB: Chalkbrood severity at 1 week  * 7.1_brood: Brood area at 1
 week  * 7.5_CB: Chalkbrood severity at 12 days * 7.5_brood: Brood area at
 12 days * 7.8_CB: Chalkbrood severity at 2 weeks * 7.8_brood: Brood area
 at 2 weeks * 7.11_CB: Chalkbrood severity at 17 days * 7.11_brood: Brood
 area at 17 days  * 7.15_CB: Chalkbrood severity at 3 weeks * early2avg:
 Early sign severity at 2 days * early4avg: Early sign severity at 4 days *
 early1weekavg: Early sign severity at 1 week * early12avg: Early sign
 severity at 12 days * early2weeksavg: Early sign severity at 2 weeks *
 early3weeksavg: Early sign severity at 3 weeks #### File:
 Carver2023RStudio.csv **Description:** Data from study in Minnesota
 2023. Cells that are blank (missing values) or containing NA values
 indicate that data was unable to be collected for that metric measured.  
 ##### Variables * Colonystand: Stand ID  * Colonynumb: Colony ID * Queen:
 Queen lines, *indicated queens that the breeder thought were extra special
 * Queen Clean: Queen lines without *for coding purposes (O = Commercial
 Line,  P = Pol-line, H = MN HYG which were not analyzed in this study) *
 june29mites: Mites pre-challenge * august1mites: Mites mid-challenge in a
 subset of colonies * sep7mites: Mites post-challenge * july19chalk:
 Chalkbrood severity at 1 week * july28chalk: Chalkbrood severity at 2
 weeks * Strict_FKB: % freeze-killed brood removed at 24 hours (strict) *
 Liberal_FKB: % freeze-killed brood removed at 24 hours (liberal)  *
 JuneFr_Brood: Frames of brood pre challenge * JuneFr_Bees: Frames of bees
 post challenge * JuneBrood_Pt: Brood pattern (1-5) pre-challenge *
 AugFr_Brood: Frames of brood post challenge * AugBrood_Pt: Brood pattern
 (1-5) post challenge * 1weekFr_Brood: Frames of brood at 1 week post
 challenge * 2weekFr_Brood: Frames of brood at 2 weeks post challenge ##
 Code/software R Statistical software, version 4.3.1 *Performance* (to
 check for model assumptions) and *ggplot2* (for visualizations) packages.
 All code used is in the file titled ManuscriptCode4.15.25.rmd  ## Version
 changes: 20-June-2025: Updated column F in BTRData2024.csv which was
 miscalculated.