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 maintaining our wildlands. This Project evaluated the diversity and abundance of wild bees in the U.S. and improved the management of pollinating bees for agriculture. The diversity (numbers of species) of bees is greater than all the diversity of mammals, lizards, frogs and birds put together. Each kind of bee provides a special ecological service, pollinates different plants, occurs at different times of year, and therefore, it is important to be able to tell the species apart. Methods for identifying the species within two important groups of pollinators, the mason bees (Osmia) and the carder bees (Anthidiini) were developed, and taxonomic descriptions were made. For example, the carder bees include 92 species, of which 21 are new, just discovered by ARS scientists in Logan, UT. A survey of the bees of Carlsbad Caverns National Park was conducted for a second year, revealing a high diversity of bees, including the first record of an orchid bee in the U.S. A national bumble bee survey was completed, providing the first documentation of bumble bee declines in North America. Research and technology transfer on agricultural pollination methods also progressed. Hands-on workshops were conducted to educate beekeepers and farmers on the latest methods for pollen-bee production and use. Workshops were conducted separately for almond and alfalfa seed crops. Commercialization of two new bees, the raspberry bee and the San Rafael bee, was initiated by supplying beekeepers with starting populations of these two bees for pollination of berry crops and native-plant seed crops, respectively. Research continued toward improving the rearing methods for western bumble bees, helping to make these bees more available for western agricultural systems. Research on pollinator health issues continued. Sometimes, alfalfa leafcutting bees produce two generations a year, instead of the expected one. This phenomenon was found to increase the spread of chalkbrood, a serious disease of this bee. Studies are now underway to determine what causes the bees to produce an extra generation. Experiments were initiated to evaluate how pesticides affect the nesting behavior of blue orchard bees and alfalfa leafcutting bees. Nesting females of the alkali bee, a valuable alfalfa pollinator, were found to require pollen for continued egg production, a fact not previously known. The bees feed themselves at the end of the day, after they finish providing for their nests. This means that for bees to reproduce well, flower resources must be available all day, not just in the morning. It is common for growers to apply such a large number of bees that all the nectar and pollen are used up by early afternoon, only getting replenished by the plants overnight. ARS scientists in Logan, UT, also found that communities of bees in rangelands generally survive wildfires because they tend to nest in the ground, away from the heat of fires. This is good news for our rangelands, which often experience wildfires. Bees are a necessary component for the reestablishment of native plant communities in areas ravaged by fires in the west.
1. Temperature stress can make bees more resistant to disease. Many crops require pollination by bees for high productivity. The reasons behind bee declines has been a major concern for beekeepers and researchers, and many hypothesize that the declines are a result of increased stresses leading to bees becoming more susceptible to diseases. ARS researchers in Logan, UT, found that when the alfalfa leafcutting bee was exposed to a temperature stress, either being excessively chilled or overheated, that chalkbrood infections declined. Molecular analyses revealed that stressful temperatures increased the activity of the immune system, and this activity reduced the ability of the pathogen to infect the bee. These results help us to understand the relationship between stress and disease, assisting beekeepers in maintaining healthier hives.
2. Genetic diversity of Western bumble bees declines. Several species of North American bumble bees are rapidly disappearing. To determine why populations are declining, ARS scientists from Logan, UT, investigated the possibility that the declines are related to low genetic diversity in some bees. Declining species were found to have a lower genetic diversity than stable species, and populations of the declining bee species were more isolated from one another. This work will be used to evaluate the status of other species and to determine what bees are at risk of going extinct.
3. Ground-nesting bees can survive the heat of range fires. Vast wildfires sweep over millions of acres of wildlands in the US annually, altering vegetation but with unknown impacts on pollinators. Most bees in rangelands nest underground. Heat tolerance experiments by ARS scientists in Logan, UT, show that these bees, of all ages, are not killed until soil temperatures exceed 120 degrees. However, only the top two inches of soil reach these temperatures in a fire, and 91% of the bees were found to nest deeper than two inches. Bees are critical to the success of restoration projects after wildfires, and now we know why native bees return so quickly to burned areas, even when all the plants have been destroyed.
4. Guide to Western Hemisphere carder bees created. Concerns about disappearing bees have highlighted the need for a better taxonomic understanding of native bees to assess the status of pollinators and pollination services. ARS scientists in Logan, UT, prepared a guide that allows identification for all 92 species of carder bees that occur in the Western Hemisphere. All these bees are described, illustrated, and information on their distribution, seasonality, nesting biology, and host plants summarized. Twenty-one new species were found in this effort, plus the species identifications were made for several males, where previously only the females were known. This project will aid future research on bee diversity, and has furthered our understanding of the evolution of bees.
5. Native bees visit clover crops in abundance. Growers who produce seed clover and other small-seeded legumes are renting increasing numbers of honey bee and bumble bee hives for pollination. ARS scientists in Logan, UT, evaluated the natural density of wild bumble bees in clover fields in western Oregon. Large numbers of colonies were found in and around clover fields, and the pollination service provided by the wild bumble bees was quantified. This information is now being used in conjunction with field surveys by researchers in Oregon to determine the proper number of bees needed to adequately pollinate these seed fields, allowing farmers a means to determine whether to rent hives.
6. Blue orchard bees like to keep their homes nearby. Blue orchard bees can be very effective pollinators for almonds, but the best methods for releasing the bees on large farms has been uncertain. The bees readily nest in plastic boxes hung from almond trees. ARS scientists in Logan, UT, found that hanging many small nest boxes evenly distributed throughout the orchard results in more bees nesting than when fewer, larger boxes are used. More nests mean more bees for the next year. It also means that more flowers are being pollinated, increasing nut yields.
Hodgson, E.W., Pitts Singer, T., Barbour, J.D. 2011. Effects of the insect growth regulator, novaluron on immature alfalfa leafcutting bees, Megachile rotundata. Journal of Insect Science. 11:43.