Source: PURDUE UNIVERSITY submitted to
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
Funding Source
Reporting Frequency
Accession No.
Grant No.
Project No.
Proposal No.
Multistate No.
Program Code
Project Start Date
May 15, 2020
Project End Date
May 14, 2023
Grant Year
Project Director
Harpur, B.
Recipient Organization
Performing Department
Non Technical Summary
Honey bees are the most important managed pollinator in the United States. Despite extensiveinvestments of time and money by beekeepers and researchers, an unsustainable proportion ofcolonies are lost each year in the US. These losses are the result of multiple stressors (e.g., poornutrition, pesticide exposure) that are catalyzed by the presence of a widespread pest: theectoparasitic mite Varroa destructor. Beekeepers have responded to Varroa by developing honeybee stocks that are mite-resistant. There are dozens of such stocks available to beekeepers acrossthe country. Unfortunately, beekeepers are often left to rely on anecdotal evidence regarding howregarding how successful each stock will be in their apiaries. We propose leveraging our existingbeekeeper-driven breeding program for a Varroa resistance trait called 'mite biting behavior' togenerate relevant data on the performance and profitability of multiple commercially availablehoney bee stocks. Working closely with beekeepers and beekeeping organizations in Indiana andPennsylvania, we will distribute colonies originating from four commonly-used honey bee stocksto beekeepers across each state. For two beekeeping seasons, we will work with these beekeepersto monitor the expression of traits associated with colony health and profitability in each of thesecolonies. Our long-term goal is to generate evidence-based data that will help beekeepers choosethe best stocks to increase the sustainability and profitability of their beekeeping operations. Thisproject systematically engages stakeholders and state apiarists through hands-on trainingworkshops, data collection, the creation of extension materials, and dissemination ofresults.
Animal Health Component
Research Effort Categories

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
Knowledge Area
307 - Animal Management Systems;

Subject Of Investigation
3010 - Honey bees;

Field Of Science
1060 - Biology (whole systems);
Goals / Objectives
The honey bee, Apis mellifera, is the most important agricultural pollinator. Through pollination, they contribute at least $19.2 billion annually to the United States economy and they contribute an additional $4.74 billion through the honey industry (Calderone 2012; Matthew et al 2018). Despite their agricultural and economic importance, honey bee populations have declined by 61% in the US during the past 70 years (vanEngelsdorp and Meixner 2010). Beekeepers today expect to lose an average of 40% of their colonies yearly. In Indiana and Pennsylvania, annual losses can be as high as 60% (Kulhanek et al. 2017; Sadler 2018). The cause of elevated loses is largely attributed to pathogens and pests. Without a doubt, the ectoparasitic mite Varroa destructor causes the greatest damage among all the other apicultural stressors (Boecking and Genersch 2008). Mite control is therefore critical for honey bee survival.Beekeepers have responded to emerging pathogenic or parasitic threats, such as Varroa, by artificially selecting for resistance traits. The United States has a long history of breeding honey bees for traits that confer resistant or tolerant to pests and pathogens (e.g. Bailey 1968; Sugden 1982; Spivak and Gilliam 1998a, b; Rinderer et al. 2010). In addition, US bee breeders often incorporate other traits as well: docility (Langstroth and Dadant 1922; Meixner et al. 2010), higher honey production (Meixner et al. 2010), lower propolis production, and 'beauty' (Langstroth and Dadant 1922). There are dozens of beekeeper-driven breeding organizations around North America that aim to maintain stocks resistant to mites. These include the Ontario Bee Breeders Association in Canada, the Russian Honey Bee Breeders Association in the US, and the Heartland Honey Bee Breeders Cooperative (HHBBC) in and surrounding Indiana. PD Harpur is the Scientific Director of the HHBBC, a group of beekeepers dedicated to maintaining the 'Purdue Mite Biting' stock of honey bees that are resistant to Varroa destructor. This stock and others (e.g. 'Italian', 'Russian', 'Buckfast', 'Minnesota Hygienic', and 'Carniolan') are available for beekeepers to purchase and beekeepers pay a premium to receive colonies bred within specific stocks.Breeding efforts have had some success at increasing the frequency of resistance traits in honey bees (e.g. Stokstad 2019). Unfortunately, there are few extension recommendations for beekeepers about which stocks they should use in their operations. Nor are there data sets available that document stock performance--how well a given stock is expected to survive and thrive within a given location. This leaves beekeepers with only anecdotal evidence about which stock will be best suited to their needs. Ultimately, beekeepers have many stocks available to them but are often unaware of which is best for their operation.We propose a collaborative, stakeholder-driven project to address this urgent need for beekeepers in the Midwest and Northeast. We will undertake a large phenotyping study (N=400 colonies) comparing the health and profitability of four commercially-available stocks widely-used by beekeepers in our regions. Each stock will be sourced from known breeders early in Spring 2020, established as single colonies, and provided to beekeepers within Indiana and Pennsylvania. Every month for two beekeeping seasons (May - September 2020 and 2021), we will work with beekeepers to quantify health- and profit-associated traits for each colony. Our results, along with hands-on phenotyping demonstrations, will be provided to beekeepers through annual hands-on demonstrations at Purdue University and the Pennsylvania State University. Our work will accomplish two major objectives:Objective 1: Assess the health and profitability of four honey bee stocks within the Midwest and NortheastObjective 2: Disseminate our findings to beekeepers in the form of field days, hands-on workshops, extension materials, and peer-reviewed work.?
Project Methods
The overall goal of this project is to generate science-based data and extension materials on the performance and profitability of multiple honey bee stocks when distributed across Indiana and Pennsylvania. We aim to develop a database of performance traits (Table 1) associated with each stock within each region. Specifically, we will compare the following four stocks:? California and Georgia Commercials: These mass-produced stocks are used by beekeepers across the country. They are typically referred to as 'Italian' (in the case of California, occasionally 'New World Carniolan').? Pennsylvania "Ferals": Several chemical-free beekeepers in Pennsylvania have maintained a survival stock started from feral honey bees without miticide treatment for over five years. Colonies will be purchased from bee breeder Bruce Rodríguez (Bernville, PA).? Purdue Mite Biters (Hunt et al. 2016): This stock has been developed since 2007 at Purdue University. Each year, queens are created from colonies expressing the highest level of mite-biting behavior. These are instrumentally-inseminated with drones from other high mite-biting colonies. Those mated queens are distributed to beekeepers across seven states (including Indiana and Pennsylvania).Objective 1: Assess the health and profitability of four honey bee stocks within the Midwest and NortheastDesign and Methods:Stage 1 - Sampling and Apiary Set-up: We will begin by sourcing stocks of honey bees from vetted bee breeders across the United States and from those which produce honey bees on large scales for commercial and hobby beekeepers. We will source California Commercial (Strachan Apiaries), Purdue Mite Biters (Hunt et al. 2016), Pennsylvania "Ferals" (Bruce Rodriguez), and Georgia Commercial colonies. These stocks are often used by beekeepers and/or purchased at a premium cost because they are 'identified' stocks that express valuable traits. We will purchase 400 total colonies (100 from each stock) as 5-frame 'nucleus colonies' containing frames of workers and a single, marked queen. Two hundred will be shipped to Purdue and the remaining two hundred will be shipped to Penn State. This will take place in Spring 2020. Each nucleus colony will be distributed into standard 10-frame Langstroth colonies with a screened bottom board. PD Harpur and Co-PD López-Uribe will provide 20 colonies (5 from each stock) to at least 5 beekeepers in each state (for a total of at least 10 beekeepers). These beekeepers regularly maintain at least 100 colonies of their own and will have indicated that they are interested in taking part in scientific research with their colonies. When provided with colonies, beekeepers will be kept blind to the source stock of each colony. Each beekeeper will also be provided with cardboard sticky boards, 50 ml sampling tubes, and an alcohol wash jar. They will be provided with detailed sampling instructions, contact information for PD Harpur and Co-PD López-Uribe, and instructions on how to manage the experimental colonies. Of importance, we will instruct beekeepers to keep each colony as a single 10-frame colony upon which they can add 'shallow' 10-frame boxes to collect honey.Stage 2 - Phenotyping and Data Collection: Beginning in July 2020 and ending in September 2020, we will work closely with each of the 20 beekeepers to sample from and phenotype the 400 experimental colonies within our study. Once per month, we will visit each beekeeper to assist in data collection. With each beekeeper, we will record the presence of a marked queen, the number of frames containing honey, the number of frames containing brood, the colony's weight, and the presence or absence of any diseases. If unmarked queens are found, they will be marked and their presence recorded.Phoretic Mite Loads: Forty-eight hours prior to our visit, each beekeeper will place a single cardboard sticky board (labelled with the date and colony ID) underneath each experimental colony for 48 hours to collect fallen Varroa mites. After 48 hours, the beekeepers will remove the cardboard sticky boards from each colony and, with our assistance, perform a standard alcohol wash of 300 bees (125 mL) to estimate phoretic mite loads (Dietemann et al. 2013b).Colony Weight and Honey production: Both the amount of honey and the overall weight of a colony are important factors for its health and profitability. Each month, we will measure weight gain and the number of fully-drawn and capped honey frames within each 'super' box added by beekeepers. In July, boxes of honey will be removed from the hives when the honey is ripe and capped. The boxes will be weighed before and after extraction of the honey to record the amount of honey that has been harvested and can be sold.Mite biting: Sticky boards will be collected after they are under the hives for 48 hours and covered in plastic wrap. They will be collected at each monthly visit by our sampling teams. Fallen mites on sticky boards will be removed at the Purdue University Research Apiary where each mite will be examined for biting damage (Hunt et al. 2016) and biting behavior will be scored as the percentage of total mites with evidence of biting damage.Viral loads: At each visit, we will collect samples of 50 in-hive worker bees to quantify viral infections of DWV, BQCV and IAPV. RNA will be extracted from the abdomen of pooled individuals per colony using the ToTALLY RNA Kit (Thermo Fisher) and converted to cDNA for downstream qPCR amplification using the Power SYBR Green Master Mix. We will do an absolute quantification of these viruses using gBlocks for each of the viruses. In addition, we will use Elongation Factor 1 alpha (EF1-a) as a positive control reference gene for honey bee amplifications (Lourenço et al. 2008) Three replicates of each qPCR reaction will be averaged and we will repeat reactions that do not have efficiencies above 95%.Overwinter survival: After the sampling season, beekeepers will overwinter each of the colonies in accordance with the best practices established in their state. In Spring 2021, colonies will be surveyed for survival (overwintering success). Each survived colony will remain within the study until Fall 2021. Beginning in May 2021 and ending in September 2021, we will repeat the sampling procedures outlined above to sample from and phenotype each of the remaining experimental colonies within our study.??Objective 2: Disseminate our findings to beekeepers in the form of field days, hands-on workshops, extension materials, and peer-reviewed work.Rationale: It is critical for beekeepers to know which stocks they should be using in their operations. It is equally critical for beekeepers to be involved in the implementation of this project and to understand how to properly quantify phenotypes they are interested in. Here, we propose a means to involve beekeepers in this work, train them, disseminate our findings to our stakeholders, and gauge if this information changed beekeepers' management practices.