Our goal is to promote the health of bee pollinators. Our primary research focus is on honey bees, ranging from basic studies on mechanisms of social behaviors to applied studies on bee breeding and management. We work as a team to provide the richest learning environment for students at all levels and from all backgrounds.

Propolis

We have initiated a series of new research projects on propolis, a complex resin that honey bees collect from some trees, such as poplar and birch in temperate regions. Bees collect the propolis on their hind legs and deposit it in the nest as a form of cement or caulk to seal cracks and to line the nest entrance and cavity. Propolis is widely known for its diverse antimicrobial properties and its value as a human medicine. Few studies have investigated the antimicrobial benefits of propolis to bees.

A. Colony-level Immune Benefits and Behavioral Mechanisms of Resin Collection by Honey Bees

• Funded by National Science Foundation, beginning 2007
• In collaboration with Dr. Jay Evans, USDA Bee Lab, Beltsville, MD

With newly available gene candidates for immunity and techniques for assessing the activity levels and efficacy of the products from these genes, honey bees are an attractive model for understanding insect innate immunity. We are exploring the evolutionary benefits of resin (propolis) collection to honey bees, and the proximate mechanisms that regulate resin collection at the individual and colony-level. Harvesting a substance with antimicrobial properties that ultimately benefits the collective immune system of a group of individuals is a fascinating example of environmental effects on innate immunity.

Our first goal is to determine if plant resin plays an integral role in the colony-level defense against pathogens in honey bees. We are comparing the gene-transcript levels of seven immune-related genes in honey bees from resin-rich and resin-poor colonies, as well as levels of key pathogens in bee colonies. Our second goal is to determine the behavioral mechanisms that initiate resin collection by individual foragers by comparing the frequency of recruitment signals (dances and trembling) produced by individual resin foragers between high- and low-resin collecting colonies.

B. Does Propolis Reduce the Reproductive Success of the Parasitic Mite, Varroa destructor Mites?

• Funded by the National Honey Board

Varroa destructor continues to be a major cause of honey bee colony death in the U.S. We are investigating the effect of propolis on the reproductive success of this parasitic mite by applying propolis solution to the inside walls of a colony (as a "propolis envelope) and to combs within the brood nest. We are testing the relative efficacy of propolis collected from the tropics (Brazil) and from temperate regions (Minnesota).

C. Novel Antimicrobial Properties of Honey Bee Propolis in Human and Animal Health

• Funded by College of Agriculture, Food and Natural Resource Sciences, University of Minnesota
• In collaboration with Drs. Jerry Cohen and Gary Gardner, Department of Horticultral Science

This is a collaborative project to investigate the antimicrobial and antiviral properties of propolis. The impetus for this project stemmed from research by Drs Peterson and Gekkar in the University of Minnesota Medical School that propolis is highly active against HIV-1 in human cell culture. The specific goals of the project are to investigate the chemical components of plant resins from different botanical origins that are collected by honey bees and to identify those components in propolis that are responsible for the biological activity against bee- and human-related bacteria and viruses. The results of these studies will have strong significance for human health issues as this information will help us to better understand the potential health-promoting effects of phytochemicals present in a product collected from honey bee colonies. In addition, the results will also have great potential benefit with respect to honey bee health and other agricultural uses, which are major concerns for the agricultural industry.

Honey Bee Projects

Honey Bee Hygienic Behavior

A. Breeding Honey Bees for Resistance to Diseases and the Parasitic Mite, Varroa destructor

• In collaboration with beekeepers in MN and ND
• Funded by NC-SARE (North Central – Sustainable Agriculture Research and Education), National Honey Board, and beekeeping associations in MN, ND, SD, IA, WI, IL, and CA.

Our primary and long-term goal is to help honey bees and beekeepers by reducing 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 devasting 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.

Our "MN Hygienic" line of bees is sold throughout the U.S. We are now collaborating with the beekeeping and queen breeding industries to promote selection for this trait among a variety of other commercially available lines of bees.

B. Neuroethology of Hygienic Behavior

• In collaboration with Dr. Karen Mesce, Dept of Entomology and Graduate Program in Neuroscience
• Funded by NSF (National Science Foundation) since 1993

Our long-term goal is to understand how genetic differences between hygienic and non-hygienic honey bees translate into behavioral differences that can be attributed to neural-circuit wiring versus circuitry that is differentially modulated.

Our research has shown that hygienic bees have increased olfactory sensitivity and responsiveness to diseased brood compared to non-hygienic bees. We recently isolated a volatile compound from larvae infected with the fungal disease, chalkbrood, that elicits hygienic behavior by bees in field colonies.

We are also studying the role of octopamine and other amines in the expression of hygienic behavior. Our previous results indicated that bees collected while performing hygienic behavior had increased expression of OA (determined by immunostaining with a highly specific OA-antibody) in cells located medial to the antennal lobes. Oral administration of OA to non-hygienic bees increased their olfactory sensitivity to the odor of diseased brood. OA administered orally (OA in sucrose solution) to individually marked bees within observation hives increased the frequency of performance of the hygienic tasks by individual bees compared to same-aged control bees (fed sucrose only).

Varroa destructor

A. Reducing Pesticide Use in Honey Bee Colonies through Sound Sampling and Treatment Procedures

• Funded by Funded by NC-SARE (North Central – Sustainable Agriculture Research and Education)

The continuing, long-term goal of this research is to reduce the amount of pesticide use in honey bee colonies for the control of the parasitic mite, Varroa destructor. We are developing a simple and standardized sampling plan for commercial beekeepers to help them determine the infestation level of Varroa destructor mites in their colonies. We will guidelines for migratory beekeepers on making educated treatment decisions for the mite based on the sampling plan.

The North Central region of the US, particularly MN, ND and SD are the top honey producing states based on yield per colony, together producing over 30% of the total honey production for the nation. The reduction in pesticide use by beekeepers will increase the profitability of beekeeping, which is based on small and moderate-scale owner-operated farms, improve the quality of honey, a wholesome food product, and improve environmental quality by promoting honey bees, vital pollinators of our agro- and natural ecosystem.