1a. Objectives (from AD-416):
The long-term objective of this project is to develop the economic value of Russian honey bees (RHB) through genetic improvements and devise innovative management strategies to increase the stock’s general and pollination productivity. Over the next five years, we will focus on multiple interrelated projects with the following objectives: Objective 1: Develop procedures for identification of RHB as a stock certification tool, determine the genetic makeup of feral bees, and identify genes contributing to mite resistance and survivability. Objective 2: Develop management techniques (e.g., determine economic thresholds for mite treatment, develop cultural techniques for small hive beetle (SHB) management in standard and nucleus colonies, and determine winter management and spring build-up strategies) to build RHB populations for crop pollination (e.g., for almond). Objective 3: Determine if there are genetic components of RHB response to emerging problems (such as colony collapse disorder or CCD) once syndromes and causes are identified. Objective 4: Use traditional breeding techniques to develop RHB with improved economic traits. Objective 5: Develop procedures for routine identification of sex alleles and determine queen relationships in multiple queen colonies. Objective 6: For Russian bee stock, use molecular approaches to investigate the physiological basis for bee immune responses to fungal pathogens (such as chalkbrood), and develop strategies for controlling natural honey bee diseases. Identify molecular bases for honey bee physiological responses to chalkbrood. Identify and assess the role of genes that could potentially be involved in the antifungal activity.
1b. Approach (from AD-416):
Honey bees play a vital role in the pollination of agricultural crops valued at $14.6B annually. Demands for commercial pollination are steadily growing. However, meeting these demands is increasingly difficult due to serious biological problems. Varroa destructor, Acarapis woodi, Aethina tumida [small hive beetle (SHB)], the emerging problems of colony collapse disorder (CCD) and high winter loss of pollination colonies all are plaguing the beekeeping industry. Perhaps Israeli Acute Paralysis Virus (IAPV) and Nosema ceranae, both recently discovered in the United States will join this list of serious problems. The Russian honey bees (RHB), developed by this unit, are resistant to varroa and tracheal mites, harbor fewer SHB, are excellent honey producers and overwinter well. This research is focused on further improving RHB to increase the stock’s usefulness, especially for early season pollination via stock selection and the development of management procedures. Increasing the commercial acceptability of this mite-resistant stock may mitigate colony losses since commercial beekeepers who use RHB stock for almond pollination report only modest winter loss of colonies. Relevance to Action Plan: Marker assisted selection is a tool being developed in Baton Rouge, Louisiana. This work will be accelerated through additional funding for Russian bees. The problem to be addressed is relevant to the NP 305 Action Plan, Component 2 Bees and Pollination (Honey Bees) Problem Problem Statement 2A.3 Developing and Using New Research Tools: Genomics, Genetics, Physiology, Germplasm Preservation, and Cell Culture.
3. Progress Report:
This serves as the final report for project 6413-21000-012-00D. Research and technology transfer related to Russian honey bees (RHB) has resulted in the complete transfer of all RHB lines to industry. Using DNA markers a method to identify RHBs was developed. RHB tracheal mite resistance was shown to be regulated by a few dominant genes. Quantitative trait loci associations were found for RHB resistance to tracheal mites but were not confirmed in a validation study. Management research on RHB found that RHB colonies grow larger during the winter in 8-frame hives, when fed from early November with continual supply of protein supplemented with 25% pollen and a continual trickle of sucrose syrup. Longevity of worker bees from individual colonies produced in the autumn is correlated to the survival of workers in winter clusters, providing a useful estimate of colon longevity. The honey bee diet developed by ARS produced larger colonies than other diets prior to almond pollination. Varroa mite research indicates that in Italian colonies higher levels of varroa mite infestion which are below treatment thresholds cause the loss or the early supersedure of introduced queens. RHB colonies display the Varroa Sensitive Hygienic trait quickly and to a high degree along with having several other mechanisms of resistance. Reproductive varroa mites that are released from the cells infest by hygienic behavior will infest new cells but will not be able to reproduce, explaining the high incidence of non-reproductive mites in hygienic colonies. Colonies of several different stocks of honey bees varied in the onset and severity of Deformed Wing Virus (DWV) symptomology independently from differences in the intensity of varroa infestations. This discovery opens the way to selecting honey bees that are resistant to both varroa mites and DWV. Individual brood with differential varroa infestations have differential immune response patterns. Levels of DWV increase in individual brood as numbers of infesting varroa increase confirming that varroa mites vector DWV. Measurements of the mites that fall to the bottoms of hives present novel ways to evaluate comparative resistance to varroa between colonies. Small Hive Beetle (SHB) research found that RHB are more resistant to SHB than Italian colonies. SHB populations develop well in apiaries having heavy clay soils or even volcanic rubble. SHB populations peak in the autumn suggesting that that might be the best time to trap them. SHB traps in apiaries which are white, are placed at the height of hive entrances, and are baited with yeast dough enriched with slow release ethanol are superior traps. SHB fed a diet of brood, pollen and honey had the highest fecundity. Protein-rich diets caused ovary activation and egg-laying while a diet of honey alone did not. High temperature accelerated ovary activation and egg-laying. A real-time PCR assay was developed to differentiate Nosema (N.) apis and Nosema (N.) ceranae. Variation in patriline response to N. ceranae was detected in RHB, but not Italian Honey Bees (IHB), indicating that there is a genetic component to Nosema resistance.
1. New measurements of honey bee resistance to varroa. Existing methods for evaluating resistance to varroa are difficult, time consuming and not suited for use by commercial honey bee breeders. ARS researchers in Baton Rouge, Louisiana studied the relationship of mite populations in colonies and the characteristics of the mites that fall to the bottom of the hive. They found that the number of younger mites on bottom boards is a good indication of the number of mites infesting the colony and hence can be used to measure mite population growth through time. They also found that the ratio of the number of older mites to all mites on the bottom board is related to reduced numbers of mites infesting colonies. Further development of these two measurements may produce methods for selecting honey bees that are resistant to varroa that are suitable for use by commercial honey bee breeders.
2. Variation in honey bee resistance to deformed wing virus. An important, but relatively unstudied, component of honey bee mortality associated with varroa mite infestations is the response of honey bees to the Deformed Wing Virus that the mite transmits. ARS researchers in Baton Rouge, Louisiana, studied the response to varroa in a large number of commercial honey bee stocks and found that they varied in the onset and severity of Deformed Wing Virus symptomology independently from the intensity of varroa infestations. This discovery opens the way to selecting honey bees that are resistant to both varroa mites and Deformed Wing Virus.
3. Hygienic behavior produces infertile varroa mites. It has long been known that honey bees that are highly hygienic toward brood cells having varroa mites have numerous infested cells that do not contain a reproductive mite. ARS researchers in Baton Rouge, Louisiana, discovered that reproductive mites that are released from cells by honey bees engaging in hygienic behavior infest new cells but are unable to continue reproduction.
De Guzman, L.I., Rinderer, T.E., Frake, A.M., Wakefield, M., Marris, G., Budge, G., Brown, M. 2013. Evaluation of the efficacy of small hive beetle (Aethina tumida Murray) bait and lures. The Science of Bee Culture. 5:3-6.