The goal of our bee research in the Spivak lab is to promote the health of all bees. Our primary research focus is on honey bees, ranging from basic studies on mechanisms of social immunity and behavior, to applied studies on bee breeding and management.
Honey bees collect resins on their hind legs from a variety of plants and deposit them in the nest cavity where the resins, often mixed with wax, are called propolis. Two graduate students, Mike Simone-Finstrom (PhD 2010) and Renata Borba (PhD 2015) demonstrated that the presence of a propolis envelope on the inner walls of the nest cavity acts as an antimicrobial layer that enshrouds the colony, providing a quantifiable constitutive benefit to bee immune defenses (Simone et al., 2009; 2017; Borba et al. 2015; 2016) and in some cases supported colony health and survivorship. The propolis envelope also directly reduces the clinical symptoms of two honey bee diseases, chalkbrood and American foulbrood (Simone-Finstrom and Spivak, 2012; Borba and Spivak, 2017). Propolis use by honey bees is an example of social immunity, and is a unique example of social-medication, since bees increase resin collection after challenge with a fungal parasite (Simone-Finstrom and Spivak, 2012).
Based on Mike Wilson’s research (PhD 2013, advised by Dr. Jerry Cohen, Plant Biological Sciences) we are now able to identify the plant source of many honey bee collected resins using metabolomics (Wilson et al., 2013; 2015; 2017). Comparing individual resin loads collected from the hind legs of bees with resin collected directly from a variety of trees, we demonstrated that honey bees collected the majority of their resins in our area from cottonwood trees, Populus deltoides. Resin from P. deltoides has antimicrobial activity against the bacterium Paenibacillus larvae and the fungus Ascosphaera apis, the causative agents of American foulbrood and chalkbrood, respectively. The major antimicrobial compounds in these resins has been identified as a series of novel 3-acyl dihydroflavonols.
Current research focuses on developing strategies that beekeepers can use to encourage their bees to construct a healthy propolis envelope, such as testing rough surface textures to stimulate resin collection and using selective breeding to develop bees with propolis-collection genetics.
Current graduate student Maggie Shanahan and research technician Héctor Morales Urbina are also investigating the importance of propolis to stingless bee health in Chiapas, Mexico.
The publications cited above can be downloaded from here. Research on propolis funded primarily by NSF IOS-0717530 and IOS-1256992 to M. Spivak.
Honey Bee Hygienic Behavior and Bee Breeding
Our (M. Spivak and G. Reuter) primary and long-term goal is to help honey bees and beekeepers reduce the amount of antibiotics and pesticides used in beehives to control diseases and parasitic mites. We have been breeding bees for resistance to these maladies since 1993 with the aim of "getting bees back on their own six feet" to end their reliance on chemical treatments for survival. A reduction in the use of antibiotics and pesticides will reduce operating costs for beekeepers, while ensuring healthy, strong colonies for honey production and pollination, and the purity of honey, wax and other marketable bee products.
Hygienic behavior of honey bees is the main mechanism of resistance to the devastating bacterial disease, American foulbrood, and the fungal disease, chalkbrood. Hygienic bees detect and remove infected brood from the nest before the pathogen becomes infectious. In 1993, we began by breeding a line of honey bees for hygienic behavior with the goal of testing if the behavior is also an effective mechanism of resistance to the parasitic mite, Varroa destructor. Extensive field trials at the University and in collaboration with commercial beekeepers have shown that bees bred for hygienic behavior do detect and remove mite-infested worker brood, and colonies bred for the behavior have reduced mite loads compared to unselected control colonies.
Although our "MN Hygienic" line of bees is sold throughout the U.S., our current emphasis is helping beekeepers and bee breeders select for this and other resistance traits from among their own lines of bees. Read about it: The future of the MN Hygienic stock of bees is in good hands! (.pdf). We are also working one-on-one with members of the California Bee Breeders Association to help them select for disease and mite-resistance from among their tried-and-true stocks.
Our aim, is to promote genetic diversity, resilience and healthy bees, and we feel that working directly with queen breeders is the best way to accomplish our goal.
Research on breeding currently funded by USDA-NIFA 2018-67013-27532 to M. Spivak.
Pathogens and Cell Line
Mike Goblirsch (Post-doctoral Researcher) developed the first continuous cell line derived from honey bee embryonic tissues; his ongoing research utilizes this research tool to better understand some of the challenges that honey bees are confronted with. An in vitro system derived from honey bee cells is beneficial for: 1) determining how factors such as intracellular pathogens or toxicological agents interact with host cells to negatively affect bee health; 2) developing diagnostic assays and screening novel therapeutics against emerging bee diseases such as viruses; 3) assessing pesticide toxicity, using wells of a culture plate as experimental units instead of entire honey bee colonies; and 4) uncovering regulatory networks and functional evaluation of the honey bee genome through RNA interference (RNAi) gene silencing technology.
Honey bee foraging preferences and native prairie flowers
Morgan Carr-Markell (PhD candidate, funded by Costco Foods) studies honey bee use of native prairie plants as food sources. Recently, movements have grown to help honey bee populations and to restore native prairie ecosystems. It would help to know whether native prairies can attract and benefit non-native honey bees. To identify and assess the most attractive native prairie plants, she collects pollen and honey from colonies placed near large, reconstructed (recently planted) prairies. She looks at the pollen grains in these samples under the microscope and identifies them based on their structure. In addition, she videotapes waggle dances (signals between honey bee foragers about where the best flower patches are) and maps the dances to determine what proportion of the bees’ favorite flower patches is within prairies.
Ian Lane (Masters degree, 2016, funded by MN Environmental and Natural Resources Trust Fund) is studying how commercial turf grasses and flowering plants can be combined to create foraging patches for bees in home lawns. As flowering resources are removed from the landscape by human development, new tools are needed to ensure the health of managed and wild bees. Turf grass represents a significant portion of cultivated land in the United States (40 million acres), and is classically devoid of flowers. Investigating new ways of managing and planting turf lawns with flowering plants holds the potential to greatly improve the foraging resources available to bees in highly developed areas.
James Wolfin, (Masters student, funded by MN Environmental and Natural Resources Trust Fund), is working in collaboration with Minneapolis Parks and Recreation Board to establish flowers into existing turf lawns in neighborhood parks. These flowering lawn patches are being monitored for establishment and bee visitors, and compared to bees visiting turf lawns that only have the common lawn flower, white clover. The goal is to determine how floral enhancement of urban lawns affects the abundance and richness of bees.