1a. Objectives (from AD-416)
The overall goal of this project is to ensure the productivity and profitability of insect-pollinated crops by improving the diversity and availability of pollinators for U.S. agriculture. In general terms, we wish to create a toolbox of pollinators. To accomplish this, we seek to understand the diversity and abundance of wild bees in the U.S., and to develop methods for managing a selection of bees as pollinators, including developing effective methods for mass production, ultilization and disease control. To attain our objectives, we plan to focus on specific ecological and agricultural systems. Objective 1: Improve maintenance of wild lands and native bees by (a) enhancing knowledge of native bee pollination, systematics and biodiversity (especially for megachilidae and bombus), (b) developing identification keys that are friendly to non-experts monitoring native bees, and (c) restoring wild lands by identifying the native pollinator guilds necessary for commercial seed farming of native forbs. • Subobjective 1.1. Expand the taxonomy and systematics of native bees, especially Megachilidae, and develop user-friendly identification keys. • Subobjective 1.2. Document the diversity of native bees in the U.S. • Subobjective 1.3. Develop pollination systems for commercial production of native plant seed needed to restore plant communities on public lands in the Intermountain West. Objective 2: Deliver improved pollination management systems for non-apis bees, particularly the Alfalfa Leafcutting Bee (ALCB) and the alkali bee for alfalfa seed production, bumble bees for greenhouse and field crops, and the Blue Orchard Bee (BOB) for orchard crops. • Subobjective 2.1. Improve sustainability of commercial populations of alfalfa leafcutting bees (ALCB) used for alfalfa seed production. • Subobjective 2.2. Improve methods for maintaining alkali bees for alfalfa seed production. • Subobjective 2.3. Improve management methods of Osmia bees for crop pollination, focusing on managing blue orchard bees to pollinate almonds and Osmia aglaia for bramble fruits • Subobjective 2.4. Develop methods to increase retention of managed solitary bees, particularly the blue orchard bee and alfalfa leafcutting bee. • Subobjective 2.5. Develop management methods for bumble bees native to the U.S. Objective 3: Develop effective and grower-friendly systems for managing diseases in non-apis bees, particularly chalkbrood in the ALCB and BOB. • Subobjective 3.1. Determine chalkbrood epidemiology and diversity (through molecular systematics), and elucidate the genetics of bee immune responses and pathogen resistance. • Subobjective 3.2. Discover effective fungicides and other suppression tools,develop application methods for controlling chalkbrood in the ALCB, and use this as a model for chalkbrood control in BOB. • Subobjective 3.3. Discover the key pathogens and parasites that inhibit mass production of bumble bee colonies.
1b. Approach (from AD-416)
Bees are vital to agriculture. The commercial production of more than 90 crops are accomplished through bee pollination. The honey bee is the best known crop pollinator, but recently, honey beekeepers have been facing a bee health crises, and significant scientific time and effort has been put into identifying the cause. The issue can be viewed as a more general problem, one of a declining availability of pollinators for agriculture. As such, another approach to avoiding the crises can be taken, and that is to evaluate the diversity and use of many species of bees. Our plan addresses three main objectives (1) improve native bee diversity and abundance, and knowledge of their biology, (2) deliver improved pollinator management systems, and (3) develop effective disease management systems for non-Apis bees. Our results will develop an understanding of the causes behind pollinator declines, improve pollinator availability, improve crop quality and production for pollinated crops, and enhance the development of new cropping methods (such as covered row crops). Our overriding goal is to provide agriculture with a tool box of pollinators, however, all bees have their own diseases and parasites and are susceptible to environmental use of pesticides and loss of habitat. Research is needed to identify and control the negative impacts of these factors. In addition, many species of wild bees provide free pollination services for agricultural crops and maintain plant reproduction in our rangelands and other natural and wild areas, and thus it is important to evaluate and protect their populations.
3. Progress Report
Pollination is vital to U.S. agriculture and to the maintenance of our wildlands. Reproduction in many plants, and the commercial production of more than 90 crops, including almond, apple, cherry, cranberry, blueberry and squash, as well as numerous seed crops, are accomplished through bee pollination. Research has continued to evaluate the diversity and abundance of wild bees in the U.S., and to devleop methods for managing a selection of bees as pollinators, including developing effective mass production, release, and disease control methods. Studies of bee taxonomy and systematics continued on the megachilid bees (leafcutting and mason bees), a group of bees that are important pollinators in native systems and that have potential as managed pollinators. The US National Pollinating Insects Collection continues to grow, and the collection data has expanded to 612,339 identified specimens, making it a rich source of information for pollination researchers. The first of a five year cooperative project was initiated with California extension personnel to demonstrate the utility and sustainability of blue orchard bees for pollinating California almonds. The blue orchard bee is now being used by several experienced orchard producers. Research on nesting behavior in solitary bees continues. Research toward the development of novel bumble bee pollinators for agricultural use was continued, and bumble bee populations were surveyed throughout the western US to identify the current health of bumble bee populations. Several bee health issues were addressed this year including the environmental causes for pollen ball syndrome (early death of alfalfa leafcutting bee larvae); an evaluation of the best number of alfalfa leafcutting bees to release for alfalfa seed production (to optimize pollination, yet still maintain good bee health); and research on the transmission, distribution and control of chalkbrood disease in the alfalfa leafcutting bee continues. A systematic analysis of the chalkbrood pathogen group is underway, and an evaluation of the immune response of alfalfa leafcutting bees when exposed to this disease has been nearly completed. Studies on disease transmission also continues, and new fungicides are being evaluated for their efficacy as an application to control the disease. Research was initiated on the use of predatory nematodes to control pests of the alkali bee (another alfalfa pollinator) and seed predators of legumes. The salty soils of alkali bee nesting beds may prevent this method from being effective.
1. Immune systems discovered for the alfalfa leafcutting bee. A library of expressed genes from healthy and chalkbrood-infected alfalfa leafcutting bees was developed, and from this, 116 immune response genes were identified for this solitary bee. The immune response systems in honey bees was previously found to be much smaller than for other insects, and this same feature was found for the alfalfa leafcutting bee. Virtually nothing is known about disease resistance in bees, and a better understanding will help scientists develop better disease control methods for bees.
2. Alfalfa leafcutting bee use improves with proper stocking density. When bees are released in field cages at rates typical for use by U.S. alfalfa seed growers, ARS scientists found that this was too many bees, making them less efficient at pollinating flowers and causing them to produce fewer healthy offspring, as compared to when more modest numbers of bees are used. The alfalfa leafcutting bee is commonly used to pollinate alfalfa for seed production in the United States and Canada, but these bees frequently have problems with disease, parasites, predators, and unexplained morality of eggs and small larvae. When too many bees are placed in fields, they compete for food and nesting sites, which results in poor bee returns.
3. Blue orchard bees as a supplement to honey bees for almond pollination. Hand’s-on practical expertise on blue orchard bee management for almond pollination was developed by ARS scientists and a demonstration project was initiated with extension personnel. Bee reproduction rates in commercial almond orchards was variable during a wet year, although bees in some orchards did increase in number. In a previous year, when weather was better during almond bloom, blue orchard bee populations increased at every site and pollination was successful. Guidance on managing blue orchard bees for almonds is now available for newcomers to the use of this bee.
4. Construction of historic range maps for declining bumble bees. Currently, at least five North American bumble bee species are disappearing, with one species thought to have gone extinct within the last five years. Despite the rapid loss of these important pollinators, little is known about the cause of their demise. ARS scientists developed a method for determining the extent and cause of these losses using geographic information systems (GIS) and historic records of bumble bee collections to create models that can predict the geographic range of the bees at different points of time in history. This new method could be used for other pollinators to help scientists understand the effects of climate change or the accidental introduction of pathogens.
5. Fire increases pollinator diversity. Fires represent major ecological forces shaping forested regions. Controlled burns constitute one method used to manage fuel loads in natural areas. Zion National Park has an active fire management program, but the effects on pollinators remains unknown. Zion National Park is home to 474 different kinds of bees, and these bees are the principal pollinators in forests and shrublands, helping maintain plant diversity. ARS conducted a two year study in Zion National Park comparing bee pollinators in adjacent plots of burned and unburned forest and shrubland. In most cases, bee abundance was significantly greater in the burned areas two to five years after the burn. Burns thus represent opportunities for increasing pollinator populations until forest regeneration.Cane, J.H. 2009. Pollen Viability and Pollen Tube Attrition in Cranberry (Vaccinium macrocarpon). Acta Horticulturae 810:563-566.