"Bees, particularly honey bees, are essential for pollination of crops, vegetable gardens, fruit trees and wildflowers. Parasitic mites and diseases are killing honey bees worldwide in record numbers, threatening the quality and availability of much

The United States is facing a pollination crisis. Both wild and managed bee pollinators are disappearing at rapid rates due to habitat loss, pesticide poisoning, diseases, and pests. Pollination is critical to successful commercial orchard and field-crop production, endangered species protection, urban gardening, ecological restoration, and forage production for the dairy and beef industries. Growers of apples, almonds, cherries, blueberries, cucumbers, pumpkins, cranberries, alfalfa, and many other crops depend on bee pollinators, both managed and wild, to produce fertile seeds and full-bodied fruit.

Two parasitic mite pests of honey bees were introduced into the U.S. in the 1980's: the tracheal mite, Acarapis woodi; and the most destructive mite, Varroa destructor. These mite pests have had a devastating effect on honey bee colonies and beekeeping businesses throughout the United States. The mites are specific pests of honey bees and do not affect bumblebees and other bee pollinators. Control measures for the mites have dramatically increased operating costs for beekeepers and many have gone out of business, resulting in a decline in national honey bee colony counts from an estimated 4.3 million in 1985 to 2.7 million in 1995. To control the mites, beekeepers have resorted to the in-hive use of pesticides, which have the potential to contaminate honey, beeswax, and other hive products. In recent years, the mites have developed resistance to the registered pesticides, and beekeepers are desperately seeking alternative controls.

In 1996, another problem of honey bees emerged. The most virulent bee brood disease of honey bees, American foulbrood (caused by the bacterium Paenibacillus larvae) has been controlled for the last 50 years by the use of an antibiotic, oxytetracycline. Most beekeepers routinely give preventative treatments of the antibiotic because the spores of the bacterium remain virulent in the wax combs for over 50 years. However, strains of bacteria have been found nationwide that are not inhibited by the antibiotic, and beekeepers are also seeking solutions to this problem.

The first goal of our research is to breed honey bees that demonstrate resistance to diseases and mites. We have bred a line of honey bees for hygienic behavior, which is the main mechanism of resistance to two diseases of honey bees (American foulbrood and chalkbrood, a fungal disease). Hygienic bees are able to detect and remove diseased brood from the nest, eliminating the disease before the pathogens reach the infectious stage. Our hygienic line is highly resistant to these diseases. Since 1994, we have been testing hygienic colonies to determine if the behavior would also provide sufficient resistance to the parasitic mite Varroa destructor. Our ongoing results indicate that hygienic colonies have significantly fewer V. destructor, less disease, and produced more honey than unselected, commercial colonies for up to one year without treatment. However, when mite infestation pressure was high (e.g., in migratory beekeeping operations when hundreds of colonies are moved together on trucks to a new location), the rate of removal of infested brood by hygienic bees could not outpace the rapid mite population increase, and the hygienic colonies required more frequent treatment to prevent collapse.

We are currently incorporating another trait of honey bees into the hygienic line, 'Suppression of Mite Reproduction' (SMR), which has been shown to be a more effective mechanism of resistance to the mite than hygienic behavior. In bees selected for SMR, the mites enter the brood cell to feed and reproduce, but they either die prematurely, or they do not lay eggs. We are testing reciprocal crosses between the hygienic line and the SMR line to increase mite resistance while maintaining disease resistance, high honey production and good brood survivability.

Most bee stocks in the U.S. traditionally have been good honey producers and have been easily treated for diseases and mites with antibiotics and pesticides, so until now there has been no pressure to maintain select lines of bees. Through our cooperative research with beekeepers, the hygienic line is now available commercially through a bee breeder in southern California. The line is distributed nationwide and beekeepers are realizing the benefits of using resistant stock.

The second goal is to study the life-history and social biology of bumblebees, and determine the impact of honey bees on the reproductive success of an important prairie-pollinating bumblebee, Bombus impatiens. We have learned to rear B. impatiens in the lab to study the behaviors of the bees within the nest. The degree of cooperation and conflict among queens and workers in bumblebee societies and the division of labor among workers depends on the degree of genetic variation among individuals, which depends on the number of males that mate with the queen. Using microsatellite DNA techniques, we are investigating whether bumblebees are polygynous. We have also revealed a large amount of information on life-history strategies of this bumblebee, which will assist in its conservation. Also, our study on effects of competition between honey and bumblebees on reproductive success of bumblebees indicate that there is resource competition between the species, which has a negative effect on the production of bumblebee queens and males.

Many different kinds of crops depend on pollination from bees. Honey bees are the primary pollinating insect in North America and an estimated $14 billion worth of agricultural commodities depend directly on or benefit indirectly on pollination from them. Therefore, the continued availability of pollinators is of great economic importance to producers of agricultural crops as well as to beekeepers. More specifically, this research will help beekeepers throughout the nation save money by eliminating altogether the use of antibiotics, and reducing the amount of pesticides used annually.

The hygenic queens resulting from research by Dr. Marla Spivak have been a boon to beekeepers such as Darrel Rufer, who lives in Waverly, Minnesota. Rufer, whose bee business is also carried out in Texas in the winters, is pleased with the hygenic queens. He and other Minnesota-based beekeepers who winter their bees in Texas bid as a group at an auction of the Minnesota hygenic breeder queens. Money from the auction of the bees goes to the Minnesota Honey Producers' Association. Using the hygenic queens has meant a reduction in all diseases, especially chalkbrood, Rufer said. The chalkbrood reduction alone would have been enough, he noted. Rufer, quoted in an extensive story about his beekeeping operation in the October, 2001, issue of "American Bee Journal," said, "The [hygenic] bee is pretty docile, produces a lot of honey, and overwinters excellent. We've geen using hygenic queens for four years now, and we're quite happy with them."

Halting, and possibly reversing the decreasing numbers of pollinators is of crucial environmental importance. Preserving healthy bee species aids in such environmentally sensitive issues as restoration of ecologically fragile habitats and protection of endangered species. In addition, research to find an alternative to pesticide control of two parasitic pests of honey bees may result in more ecologically friendly methods of controlling the mites.

Pollinators make many of our pleasures possible, including blooming gardens and healthful fruits and vegetables. This research may ensure that pollinators are protected, thus helping to maintain a good quality of life.

Minnesota County
All Counties, International, National, Upper Midwest

Primary Researcher
Marla Spivak
spiva001@umn.edu

Participating Individuals
10 Undergraduate Students
3 Graduate Students
2 Post Docs
8 Volunteers

Participating Institutions
Agriculture Utilization Research Institute-Pesticide Reduction Option (AURI-PRO) Sustainable Agriculture Research and Education (SARE) Beekeeping Associations in: MN, ND, SD, IA, WI, CA, IL

Department
Entomology

Government Funding Type
External
Federal
State

Additional Funding Information
Average annual funding is $1,500,020.00