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United States Department of Agriculture

Agricultural Research Service

Research Project: Managing and Conserving Diverse Bee Pollinators for Sustainable Crop Production and Wildland Preservation

Location: Pollinating Insect-biology, Management, Systematics Research

2016 Annual Report


1a. Objectives (from AD-416):
Objective 1: Improve the production and management of non-Apis bees such as blue orchard bees, bumble bees, and alfalfa leafcutting bees for crop pollination by increasing knowledge of bee nutritional needs and environmental effects on bee physiology (especially on diapause and overwintering). Sub-Objective 1.1: Identify the pollen and nectar requirements for maintaining non-Apis bee fitness, in both native and managed ecosystems. Sub-Objective 1.2: Develop a better understanding of the environmental factors that affect diapause in non-Apis bees, and develop methods to improve winter survival. Objective 2: Identify environmental (e.g. poor nutrition) and biological factors associated with bee declines (non-Apis species and the honey bee) and develop methods to diagnose and control non-Apis mortality, such as pollen ball and chalkbrood, that are caused by parasites, pathogens (e.g. Crithidia and viruses of bumble bees), and pesticides. Sub-Objective 2.1: For non-Apis bees, develop methods to control pests and diagnose and treat infectious diseases. Sub-Objective 2.2: Identify the primary environmental and biological factors that affect managed bee sustainability. Objective 3: Quantify bee forage in relation to floral resources and management practices, such as grazing and improve nesting design and strategies (e.g. using chemical cues to enhance nest location), to maximize bee pollination. Sub-Objective 3.1: Improve the reproduction and health of Megachile rotundata (alfalfa leafcutting bee) and native bees by providing non-crop floral resources. Sub-Objective 3.2: Improve production systems for managed non-Apis bees. Objective 4: Improve bee taxonomy and curation and identify mechanisms that affect bee diversity to enhance conservation efforts, particularly in relation to fire and climate change. Sub-Objective 4.1: Expand the taxonomy and systematics of native bees and develop user-friendly identification keys. Sub-Objective 4.2: Evaluate bee biodiversity and improve the knowledge needed to achieve effective bee conservation and stewardship. Sub-Objective 4.3: Evaluate the effect of habitat-altering events on bee diversity and abundance, especially the effects of fire. Sub-Objective 4.4: Identify climatic factors that define the ranges, phenologies and population persistence of select native bees.


1b. Approach (from AD-416):
Bees are vital to agriculture. The commercial production of more than 90 crops is accomplished through bee pollination. The honey bee is the best known crop pollinator, but unfortunately, honey beekeepers have been facing a recent bee health crisis. Although a significant amount of scientific time and effort has been invested into identifying the causes for poor colony health, the issue can be viewed as a more general problem, the declining availability of pollinators for agriculture and ecosystems. In addition to working toward finding solutions to the health issues facing honey bees, we provide another approach: tapping into the pollination potential of the diverse bee fauna of the U.S. This project plan addresses four main objectives (Fig. 1): (1) improve non-Apis bee production and management systems, (2) develop methods to control pathogens and parasites and identify environmental stressors for all bees, (3) understand the foraging and nutritional needs of non-Apis bees, and (4) improve bee systematics and taxonomy and our knowledge of bee diversity. Our overriding goal is to provide agriculture with a tool box of pollinators. To achieve this, we must provide a better understanding of the causes behind pollinator declines, improve pollinator availability, and better understand how bee population size and density affect crop pollination. Of necessity, this requires addressing diseases and parasites, environmental impacts, and human-induced threats such as pesticides and habitat loss. Equally important is wild bee diversity. Wild bees provide free pollination services for agricultural crops, maintain plant reproduction in natural areas, and ensure a pool of future managed pollinators.


3. Progress Report:
Pollinating Insects—Biology, Management and Systematics Research Unit (PIBMSRU) aims to enhance the understanding, availability, quality, and identification of bees that support U.S. agriculture as pollinators of valuable food and seed crops. In FY2016, we made reports on solitary bees, bumble bees, and honey bees of relevance to alfalfa seed producers, almond growers, fruit growers, bumble bee producers, beekeepers, tomato producers, and agencies such as: the Animal and Plant Health Inspection Service (APHIS) Plant Protection and Quarantine Program, the U.S. Forest Service (USFS), the Natural Resources Conservation Service (NRCS), the U.S. Fish and Wildlife Service (FWS), the Bureau of Land Management (BLM), the National Parks Service (NPS), U.S. Geological Services (USGS), and U.S. Environmental Protection Agency (EPA). Consultation and expertise have been provided to private citizens and to non-profit conservation groups such as the Xerces Society for Invertebrate Conservation, North American Pollinator Protection Campaign, and the Saint Louis Zoo. We provide consultation to the Tribal Pesticide Program Council representing Native American Nations with guidance on Managed Pollinator Protection Plans. Of the more than 20,000 bee species worldwide, only a small fraction of species have been successfully managed to pollinate agricultural crops. ARS scientists at PIBMSRU continue research to improve production and management of several species of social and solitary bees currently managed in agricultural systems, and to seek novel pollinators to meet pollination needs. Comparative studies are being performed to understand how environmental stresses and pathogens affect health of honey bees, bumble bees, and solitary bees in agricultural environments. Through collaborations, our scientists continue to understand the contributions of unmanaged bees to pollination of our nation’s crops and natural ecosystems. This requires knowledge of bee taxonomy to accurately determine which species are visiting the target crops in orchards and fields. Pollen is a required food for bees that are raised in captivity, especially for commercially raised bumble bees, and must be collected in large amounts. Pollen taken from honey bee colonies with pollen traps can vector pathogens like viruses and fungi. Irradiation, ozone treatment, and ethylene oxide fumigation had significant impact on viral load, spore viability, palatability, and fatty acid content of pollen. Ethylene oxide and gamma irradiation are effective in reducing pathogens and equally palatable to bees; both are recommended for pollen sterilization. This will provide bumble bee producers with treatments before feeding pollen to bees and result in cleaner stock for growers of bumble bee dependent crops. Alfalfa leafcutting bee females provide smaller amounts of larval food early in the nesting season and produce offspring that do not undergo diapause, while later offspring are provided larger provisions and enter diapause. ARS researchers initiated manipulative experiments to determine factors that influence nesting females to supply food to larvae in differing amounts. These factors include health of female, viral diseases, and size of nest cavities. For solitary bees, bumble bees, and honey bees, abiotic and biotic factors are evaluated for impacts. For a key ground-nesting pollinator of alfalfa, an ARS scientist and a soil biophysicist from Decagon Instruments examined the water relations between nests of alkali bees and surrounding soil since these bees require moist nesting soil; the total water potentials of live eggs, larvae, provisions and soils were measured. The initial dry provisions were protected from microbial growth; and overtime, additional water was absorbed. This information reveals the importance of soil moisture for bee production. To help protect alfalfa leafcutting bees from wasp parasites and parasitoids, an ARS scientist designed kill-traps for use during incubation and at nesting sites. Trap style, color and use of leafcutting bee cocoon extract as an attractant were evaluated to determine efficacies. The developmental timing of a minute wasp parasitoid, Melittobia sp., is being determined to predict adult emergence and its infestation of alfalfa leafcutting bees. ARS researchers determined effects of several doses (lethal and sublethal) of an insecticide, a fungicide, and a spray adjuvant and their combinations on survival and development timing for blue orchard bee larvae reared on almond and apple pollen. Behavior of adult bees exposed to recently-sprayed floral resources was evaluated following applications of an insecticide, a fungicide, or combination of both. In addition, impacts on viral diseases and chalkbrood will be determined. In collaborative research with Pennsylvania State University scientists on honey bees, an ARS scientist found that a commonly-used organosilicones spray adjuvant synergized with viruses in larval food to cause increased viral titers in late instar larvae and death during pupation. Black Queen Cell Virus was primarily affected and is commonly found in honey bees, bumble bees, and some solitary bees. Organosilicones are widely used in cropping systems to increase chemical penetration and spreading. These are similar symptoms to those reported by bee keepers with elevated colony losses. Collaborations between ARS and scientists at the University of Maryland and the University of Liege, Belgium, have resulted in defining four pathologies as predictive biomarkers for honey bee colonies having an increased likelihood of undergoing Colony Collapse Disorder (CCD). Bees of known ages from both healthy apiaries and apiaries undergoing CCD were dissected. The occurrence of these four pathologies was significantly associated with bees of all ages from CCD colonies and was not found in older bees from healthy colonies. This will provide beekeepers with a method to predict the future health of colonies. Bumble bee colonies depend on healthy queens to establish nests in spring. These queen bees are solitary and susceptible to diseases and parasites not observed in other life stages. ARS researchers screened over 300 queens from six states for parasites and pathogens. Four viruses were detected, with Black Queen Cell Virus found in 19% of individuals. The most prevalent pathogen was a protozoa, Crithidia bombi, which causes low nesting success in queen bumble bees. Also notable was a queen castrating nematode found in over 7%. These results explain the low nesting success that commercial producers experience when raising colonies for pollination. The results have been transmitted to USDA APHIS to inform regulatory decisions. A two-year study confirmed that combining blue orchard bees and honey bees in almond orchards increased fruit set (average fruit set 67%) in southern Central Valley of California, as compared to only honey bees (average fruit set 30%). Overall nut yield increased but was affected by weather (heat and extended drought) and management conditions. With this proof of concept, making the blue orchard bees more affordable and available is a priority. An ARS scientist and postdoctoral associate with collaborators at the University of California, Davis and Wonderful Orchards, LLC, found that planting of spring flowers near almond orchards allows for continued nesting of blue orchard bees and increased reproduction. Once almond bloom ceased, bees used the spring flowers, as evidenced by non-almond pollen in nests. Establishment and maintenance of floral plots will be evaluated for economic feasibility and practicality. Distribution of blue orchard bee nesting boxes in commercial cherry orchards affects bee production. Females make more nests and progeny when given more small nesting boxes per acre with even dispersal as compared to a large nest-shelter in a central location. ARS scientists found that the blue orchard bee is an effective, avid pollinator of red and purple raspberries. Preliminary work was extended to multiple commercial cultivars. As compared to honey bees, blue orchard bees are more adapted to Pacific Northwest weather with cool and damp conditions. Wintering blue orchard bees at freezing delayed their spring emergence for a month to synchronize them with raspberry bloom and bees had excellent survival and reproduction. To aid the U.S. Forest Service (USFS) and the Bureau of Land Management (BLM) in developing pollinator-friendly seed mixes, PIBMSRU scientists compiled data from 12 years of sampling of bees at different forbs. Although flax and yarrow are common in current seed mixes, these do not contribute to bee conservation. To aide these agencies in native pollinator conservation, a novel calculation was developed to estimate the impact of honey bee competition with native bees for pollen and nectar resources and was derived from surveys in two states from 17 apiaries populated with 40-96 hives. In a 16 square mile area, a large apiary required as much pollen as needed to feed several million immature solitary bees. The National Pollinating Insect Collection (NPIC) and the associated National Pollinating Insect Database (NPID) are being used to investigate the taxonomy and biodiversity of native bees. These data augment ongoing studies to fill identified seasonal and spatial knowledge gaps. Current work analyzes data from NPID and the American Museum of Natural History to better understand on how conserved national areas act as reservoirs for pollinators. Data from inventory and monitoring projects conducted in collaboration with U.S. Geological Survey (USGS), U.S. Fish and Wildlife Service (FWS), Utah Cooperative Agricultural Pest Survey Program, and the the National Park Service (NPS) are used in descriptions of new species of mason bees.


4. Accomplishments
1. Almond yield increased by pollinating with Blue Orchard Bees and Honey Bees. A two-year study has confirmed that using blue orchard bees along with honey bees in almond orchards increases fruit set (average fruit set 67%) in the southern Central Valley of California, as compared to use of only honey bees (average fruit set 30%). Overall nut yield increased in many of the plots with both blue orchard bees and honey bees; however, conditions were sub optimal (a short spring and extended drought), suggesting that either with optimal weather or altered management practices that yields may be increased even more so. With these results, use of the blue orchard bee has much promise, both in maximizing orchard yields and also in helping to decrease the demands on honey bees. It is now imperative to work towards making the blue orchard bees more available and affordable, as well as working with orchard managers to convert higher fruit set to higher nut yields. Current research has promise on enabling the rearing and increased production of blue orchard bees in orchards. This research demonstrates successful use of an alternative pollinator in increasing crop yield.

2. Spray adjuvants synergize with viral exposure to cause increased mortality in developing honey bee brood. In collaborative research with scientists at Pennsylvania State University, an ARS scientist in Logan, Utah, found that a commonly used spray adjuvant, organosilicones (OSS), synergized with viral exposure in the larval food to result in increased viral titers in late instar larvae and death during pupation. Organosilicones are widely used in various cropping systems and in industrial applications to increase chemical penetration and spreading. In almonds, the amount of organosilicones spray adjuvants used in tank mixing and pesticide applications nears the amount of fungicide use. The symptoms observed in dying brood that were exposed to OSS and viral exposure are similar to those reported by bee keepers who experience elevated colony losses following pollination events in crops such as almonds. These findings identify a previously unknown factor that may be underlying increased colony loss.

3. Nationwide survey of queen bumble bee pathogens reveals potential causes for commercial losses of bumble bee colonies. Bumble bee colonies depend on solitary queens to establish nests in the spring of each year; and to be successful, these queens must be healthy and not infected by pathogens. In commercial colonies used for greenhouse pollination, increased losses are found during production. ARS researchers in Logan, Utah, screened over 300 queen bumble bees for parasites and pathogens in six states distributed across the U.S. Among the pathogens, the most prevalent pathogen was a protozoan Crithidia bombi that causes low nesting success in queen bumble bees and four viruses, with Black Queen Cell Virus found in nineteen percent of all the individuals. Also notable was the presence of a queen castrating nematode in over seven percent of the queens. These results enable commercial producers to select for pathogen-free bees for more successful colonies and will also be transmitted to the USDA Animal and Plant Health Inspection Service (APHIS) to influence regulatory decisions by that agency.

4. Patent issued for bee attractant to increase blue orchard bee nesting and production. The Blue Orchard Bee can be used for managed pollination of many nut and fruit crops. One major hurdle in its use has been getting reliable nesting within the orchards, given that this is when the bees perform pollination by collecting pollen to feed their young. An attractant has been discovered and patented (Patent # US9301521) for the Blue Orchard Bee by ARS scientists in Logan, Utah, and Fargo, North Dakota, along with commercial companies. Nesting boxes can be sprayed with the attractant to increase the number of bees using the box and thus help ensure reliable pollination of the crop.

5. Nationwide survey of bumble bee species abundance and distribution. Recent reports of range shifts and declines in some species abundance have raised concerns that various factors such as climate change and pesticide use might be affecting bumble bee populations. ARS scientists in Logan, Utah, completed a nationwide survey of bumble bees, collecting 4,032 bumble bees from fifteen states in wild and agricultural landscapes. These bees have been identified and represent most of the thirty-nine species that occur in the contiguous U.S. The distribution and abundance of these species have been calculated and the data will be served on public databases once published. This survey is the largest bumble bee survey looking at national distribution of all bumble bee species that has ever been done and has provided essential insight into the current status of bumble bee species.

6. Extra floral resources increase blue orchard bee reproduction after almond bloom. An ARS scientist and a postdoctoral associate in Logan, Utah, and collaborators at the University of California, Davis, and Wonderful Orchards, LLC, found that spring flowers planted near almond orchards allows continued nesting of blue orchard bees used for almond pollination. Once the almond bloom ends, no other flowers are available to provide nectar and pollen to blue orchard bees or honey bees. Bees from across the orchard found and foraged on the blooming flower plot, as evidenced by the presence of spring flower pollen in nests located almost one mile from the flower plots. The number of blue orchard bee offspring produced was one and a half times the number of the starting population of bees released in the orchard. This increased production of blue orchard bees helps guarantee successful pollination of the almonds in the upcoming year.

7. A new bee that nests in sandstone. ARS scientists in Logan, Utah, made the surprising discovery of a new species of bee that constructs its nests in sandstone, including ancient cliff dwellings. This has led to investigations into its biology. Females appear to soften the rock with water to aid in digging with their mandibles. This desert bee has the ability to remain alive as a larva for multiple years before emerging, a strategy that would appear to have great value in the harsh environments where it lives where in some years there are little or no flowers. It is remarkable also for how long these nests are used. One site has documented occupancy of almost forty years.

8. Pathological traits have value as predictive biomarkers for Colony Collapse Disorder. Collaborations between an ARS scientist in Logan, Utah, and scientists at University of Maryland and University of Liege in Belgium, have resulted in a definitive study defining four particular pathologies as predictive biomarkers for honey bee colonies having an increased likelihood of undergoing Colony Collapse Disorder (CCD). These pathologies were defined by dissecting bees of known ages from both healthy apiaries and apiaries undergoing CCD. The occurrence of these four pathologies was significantly statistically associated with bees of all ages from CCD colonies and did not occur at a significant level in older bees from healthy colonies. Identification of these traits provides bee keepers and others with a method to reliably predict the future health of colonies. In addition, the type of associated pathologies suggests that the physiology of the CCD bees is experiencing a disruption in excretion and water reabsorption and suggests that more be learned on how these physiologies are regulated in honey bees.

9. Determination of the best methods for sterilization of pollen to enable its safe use as bee feed. Pollen is important as a food for bees that are raised in captivity, especially for commercially raised bumble bee nests and may also be needed to feed honey bee colonies without available floral resources. Pollen that is fed to bees is generally removed from honey bee colonies with devices called pollen traps; however, this pollen can vector pathogens such as viruses and fungal spores. ARS scientists at Logan, Utah, conducted a test of three methods, irradiation, ozone treatment, and ethylene oxide fumigation, to sterilize pollen without affecting nutrition and palatability for bees as a diet. Both ethylene oxide and gamma irradiation were effective in reducing pathogens and equally palatable to bees, and these are recommended treatments for pollen sterilization. This research provides bumble bee producers a way to treat pollen before feeding it to bees to provide healthier colonies to growers using bumble bees to pollinate crops.

10. Adult female solitary bees must eat pollen to reproduce. An ARS scientist in Logan, Utah, and a faculty biologist from Whitman College, showed that female alkali bees (used commercially for alfalfa pollination) begin eating pollen on their day of emergence, and continue to eat two to three daily pollen meals amid nesting activities for their entire adult lives. All females ate a pollen meal at day’s end, the very time that pollen resources are most depleted, a risk of overstocking managed pollinators. Subsequent greenhouse experiments with a cavity-nesting Osmia bee species showed that females confined with male-sterile sunflowers could not develop their first egg, whereas those availed pollen-bearing sunflowers ate pollen regularly, grew their first oocytes, nested and laid mature viable eggs. Deploying managed populations of solitary bees before bloom risks delayed or interrupted reproduction, and overstocking them risks short-changing nesting females of necessary dietary proteins needed for yolk synthesis.

11. World class bee collection expanded. Essential information on the biology and distribution of native bees is needed both for managing bees and conserving them and the services they provide. Institutional collections of bees are invaluable resources for ascertaining the status of the pollinators essential for successful reproduction of plants in agricultural and natural environments. ARS houses the U.S. National Pollinating Insects Collection (NPIC) in Logan, Utah, the largest collection of bees in the world, containing approximately 1.4 million specimens from 136 countries. Data from the insect labels, including the identity, date and time of collection, host plant, and gender, has been entered into a specimen-level relational database to increase the total to 1,422,779 records. The NPIC is an invaluable reference visited and used by scientists from all over the world, and the data on pollinators is made available to the public and the scientific community through the Global Biodiversity Information Facility and Discover Life websites.


5. Significant Activities that Support Special Target Populations:
During FY16, ARS scientists in Logan, Utah, actively provided consultation to the Tribal Pesticide Program Council (TPPC) representing 42 Native American Tribal Nations in providing advice and guidance on their Managed Pollinator Protection Plans, given their focus on native bee populations. Two meetings were attended, with a presentation given to help educate the Native Americans about the native pollinators and impacts that may be occurring between environmental stresses and their interactions with diseases. Continued advice will be given in FY17. Three Native American undergraduate students from Utah State University were hosted within our labs, each for a one-week period of time. These students were participants in the Native American Stem Mentorship program, begun with grant funding from the national Native American-Serving Nontribal Institutions initiative and that encourages to students to explore advanced science, technology, engineering, and math (STEM) educational opportunities and careers. The students worked with ARS scientists and technicians and were actively involved in research projects. Several of the projects were especially designed for their involvement. Besides giving them additional insight into scientific research, our goal was to also give them an appreciation for bees as pollinators and their roles in agricultural and natural ecosystems.


Review Publications
Cane, J.H., Love, B.G. 2016. Limited direct effects of a massive wildfire on its sagebrush steppe bee community. Ecological Entomology. doi: 10.1111/een.12304.

Sgolastra, F., Arnan, X., Pitts Singer, T., Maini, S., Kemp, W.P., Bosch, J. 2015. Pre-wintering conditions and post-winter performance in a solitary bee: does diapause impose an energetic cost on reproductive success? Ecological Entomology. doi: 10.1111/een.12292.

Griswold, T.L., Herndon, J.D., Gonzalez, V.H. 2015. First record of the orchid bee genus Eufriesea Cockerell (Hymenoptera: Apidae: Euglossini) in the United States. Zootaxa. 3957:342-346.

Artz, D.R., Pitts Singer, T. 2015. Effects of fungicide and adjuvant sprays on nesting behavior in two managed solitary bees, Osmia lignaria and Megachile rotundata. PLoS One. doi: 10.1371/journal.pone.0135688.

Orr, M., Griswold, T.L. 2015. A review of the cleptoparasitic bee genus Townsendiella (Apidae, Nomadinae, Townsendiellini) with the description of a new species from Pinnacles National Park. ZooKeys. 546:87-104.

Koch, J., Lozier, J., Strange, J.P., Ikerd, H.W., Griswold, T.L., Cordes, N., Solter, L., Stewart, I., Cameron, S.A. 2015. USBombus, a database of contemporary survey data for North American Bumble Bees (Hymenoptera, Apidae, Bombus) distributed in the United States. Biodiversity Data Journal. doi: 10.3897/BDJ.3.e6833.

Orr, M., Portman, Z., Griswold, T.L. 2015. Megachile (Megachile) montivaga (Hymenoptera: Megachilidae) nesting in live thistle (Asteraceae: Cirsium). Journal of Melittology. 48:1-6.

Nelson, R.A., Griswold, T.L. 2015. The floral hosts and distribution of a supposed creosote bush specialist, Colletes stepheni Timberlake (Hymenoptera: Colletidae). Journal of Melittology. 49:1-12.

Eardley, C., Griswold, T.L. 2015. Taxonomic revision of Plesianthidium Cameron (Hymenoptera: Megachilidae: Anthidiini), an endemic southern African bee genus. Zootaxa. 3973(1):1-56.

Cane, J.H. 2015. Landscaping pebbles attract nesting by the native ground-nesting bee Halictus rubicundus (Hymenoptera: Halictidae). Apidologie. 46(6):728-734.

Litman, J.R., Griswold, T.L., Danforth, B.N. 2016. Phylogenetic systematics and a revised generic classification of anthidiine bees (Hymenoptera: Megachile). Molecular Phylogenetics and Evolution. 100:183-198. doi: 10.1016/j.ympev.2016.03.018.

Eardley, C., Griswold, T.L. 2016. Taxonomic revision of the Afrotropical bee genus Serapista Cockerell (Hymenoptera: Apoidea: Megachilidae: Megachilinae: Anthidiini). Zootaxa. 4111(4):334-364.

Cane, J.H., Dobson, H.E., Boyer, B. 2016. Timing and size of the daily pollen meals eaten by adult females of a solitary bee (Nomia melanderi)(Apiformes: Halictidae). Apidologie. 48(1):17-30.

Last Modified: 09/24/2017
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