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.
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:
A comprehensive evaluation of all the mites collected on bottom board traps compared to the populations of infesting mites in colonies of both Russian and Italian honeybees indicated that the ratios of older mites to all fallen mites (O/T) and younger mites to all fallen mites (Y/T) produced high negative regressions. Further work may identify these measurements as new ways to select both Russian and Italian honey bees for increased resistance to varroa. Management research on Russian honey bees has determined that Russian colonies will grow larger when are fed a continual supply of a patty that is made of protein supplement and either 50% or 25% natural pollen along with a source of sugar syrup. Longevity of worker bees from individual colonies produced in the autumn is correlated to the survival of workers in winter clusters. However, this correlation was not found with worker bees caged from the colonies in the spring. Varroa mites that are released from cells they are infecting because of honey bee hygienic behavior are in a state of asynchronous development with other potential honey bee brood at the time of release. This asynchrony causes the mites to be infertile should they re-invade the brood. Auto- and allo-grooming against varroa mites results in many mites falling to the bottom of the hive that do not have apparent physical damage. Hence, assessments of grooming behavior must be refined to accommodate this observation. An improved method for marking varroa mites for capture/recapture studies was developed. A quantitative trait loci (QTL) was identified for larval resistance to the fungus causing chalkbrood. Due to the success of the project and the potential for the gene marked by the QTL to impart resistance to a second fungal problem of honey bees, Nosema (N.) ceranae, the project was extended to identify the causative factor in the larval mediated chalkbrood resistance. Fine mapping has reduced the QTL interval to a very small number of genes which are currently being evaluated for resistance function. Colony Collapse Disorder (CCD) research has shown that Russian and VSH varroa mite resistant colonies survived better than untreated Italian colonies in both cross country pollination studies and in trials in a mid-western to California pollination trial. Overall, the mite resistant stocks were equal and in some cases better pollinators than the control stock. Molecular genetic methods have been developed to detect and quantify Nosema ceranae infections. Patrilines of Russian honey bee colonies have variance in response to N. ceranae although Italian colonies do not. This indicates that the potential for breeding bees that have improved resistance to N. ceranae is greater for Russian honey bees. Feeding pollen or protein substitute to honey bee colonies through the winter increases the levels of infection of colonies by N. ceranae.
1. Winter feeding produces large Russian honey bee colonies for almond pollination. Almond pollination requires large honey bee colonies in February. This is an unusual time for honey bee colonies to be large and is especially true for mite-resistant Russian honey bees (RHB). Feeding RHB colonies from mid-November with sucrose syrup and protein patties containing 25 to 50% pollen produces very large colonies in February. This technique also is useful for managing Italian honey bees. Some beekeepers are now collecting pollen to use this technique in the coming year.
2. A single gene controls larval honey bee resistance to a fungus disease. Chalkbrood, a fungal disease of honey bee brood, periodically causes substantial reductions in colony populations and sometimes colony loss. Since no drug exists to control the disease, genetic resistance is highly desirable. Also, since the genetic system is simple, resistance to chalkbrood is an ideal trait to provide a “proof of concept” for Marker Assisted Selection.
3. A new way to measure resistance to varroa has been found. Worldwide, varroa mites are the primary cause of honey bee colony loss. Some honey bees have been bred for resistance to the mite: Russian honey bees have been bred for reduced mite levels and honey bees with the Varroa Sensitive Hygiene trait have been bred for that single trait. An additional trait for selection would be highly desirable to speed selection for improved resistance and extend selection to multiple honey bee stocks. ARS scientists in Baton Rouge, LA, have examined the natural mite fall in honey bee colonies and found that the measurement of “older mites/all mites” has a good correlation with reduced numbers of infesting mites. Further development may lead to an easy selection too for producing varroa resistance.
Bourgeois, A.L., Rinderer, T.E., Sylvester, H.A., Holloway, B.A., Oldroyd, B.P. 2012. Patterns of Apis mellifera infection by Nosema ceranae support the parasite hypothesis for the evolution of extreme polyandry in eusocial insects. Apidologie. 43(5):539-548.