Research Project: Sustainable Crop Production and Wildland Preservation through the Management, Systematics, and Conservation of a Diversity of Bees

Location: Pollinating Insect-Biology, Management, Systematics Research

2020 Annual Report

Objectives
Objective 1: Improve crop pollination by alfalfa leafcutting bees, bumble bees and mason bees by identifying the environmental and biological factors that impact bee health during propagation and pollination and develop new and improved bee management strategies to ensure healthy, sustainable pollinator populations. Subobjective 1.1: Improve best management practices for pollinator use in cropping systems that result in sustainable pollinator supply for continued crop pollination. Subobjective 1.2: Identify impacts of xenobiotic factors on managed bee health (climatic factors, phenological mismatch, temperature range, etc.), host-plant [nutritional value/ host plant chemicals], invasives, pesticides. Subobjective 1.3: Examine the linkage between nutrition and bee performance in non-Apis bees (immunity, longevity, and reproduction). Subobjective 1.4: Develop effective treatments of pathogen, pest, and parasites in non-Apis bees. Subobjective 1.5. Devise new sampling and diagnostic methods for bee pests and diseases. Objective 2: Improve bee systematics and develop new tools for rapid bee identification to enhance the understanding of wild bee diversity and the identification of environmental and biological factors that promote wild bee sustainability. Subobjective 2.1: Evaluate bee biodiversity and improve the taxonomic and systematic knowledge needed to achieve effective bee conservation stewardship.

Approach
Objective 1: Improve crop pollination by alfalfa leafcutting bees, bumble bees and mason bees by identifying the environmental and biological factors that impact bee health during propagation and pollination and develop new and improved bee management strategies to ensure healthy, sustainable pollinator populations. 1.1. Hypotheses will be tested using field studies with measurement of bee health and pollination performance to improve management of mason bees and bumble bees. Experiments will examine interactions of mason with honey bees in co-deployment and impacts on pathogens as detected using molecular methods. 1.2. Exposure to agrichemicals via soil and leaf pieces by solitary bees will be quantified. The hypothesis that sublethal exposure agrichemicals including adjuvants impacts bee health will be tested for honey bees and alfalfa leafcutting bees using experimental manipulation and examine interactions with pathogens. 1.3. Hypotheses will be tested that nutrition (amino acid and sugar sources) can impact the reproduction and life span of alfalfa leafcutting bees. We will determine how the nutritional requirements of a bumble bee colony changes during colony age, as well as the maximal and minimal foraging range of Bombus huntii. 1.4. Hypotheses to examine control of chalkbrood and pollen ball formation via antimicrobial disinfectants will be tested for solitary bees. The life cycle and control of a major emerging parasitoid (Melittobia sp.) in alfalfa leafcutting bees will be determined. 1.5. Molecular methods will identify parasites, parasitoids, and pathogens of mason bees and alkali bees. Non-lethal methods to sample bumble bees parasites and pathogens will be developed. With molecular data, we will identify the species of Melittobia found in managed bees and characterize genetic diversity across populations. Objective 2: Improve bee systematics and develop new tools for rapid bee identification to enhance the understanding of wild bee diversity and the identification of environmental and biological factors that promote wild bee sustainability. We will 1) develop up-to-date taxonomies informed by phylogeny, 2) produce web-accessible bee identification tools, and 3) capture biological data present in museum specimens. To accomplish this, we will continue our efforts to survey bees across the western U.S, digitize bee collections, and conduct systematic studies of groups in need of revision. We will use molecular data, especially phylogenomic information derived from DNA sequences using ultra-conserved elements, to build phylogenies and refine species boundaries. The sequence information will be combined with taxonomic keys and images to allow non-experts to more easily identify bees.

Progress Report
This report documents progress for Project 2080-21000-019-00D “Sustainable Crop Production and Wildland Preservation through the Management, Systematics and Conservation of a Diversity of Bees”. Of the 20,000 bee species worldwide, only a fraction are successfully managed to pollinate agricultural crops; although, pollination by native bees species can have major impact on crop yield and quality. Natural ecosystems provide habitats for native bees visiting agriculture and serve as a reserve for sourcing pollinator species. ARS scientists in Logan, Utah, continue research to improve production and management of several species of social and solitary bees, seek novel pollinators to meet pollination needs, and learn how native bee populations contribute to crop pollination. The project has two goals: (1) Improve crop pollination by non-Apis bees by identifying factors that impact bee health and develop bee management strategies to ensure pollinator populations; (2) Improve bee systematics and develop new tools for rapid bee identification to enhance understanding of wild bee diversity and presence. ARS scientists at Logan have reported research on solitary bees, bumble bees, and honey bees of relevance to the general public, alfalfa seed producers, almond growers, fruit growers, bumble bee producers, honey bee keepers, tomato producers, and agencies such as: Animal and Plant Health Inspection Service (APHIS) Plant Protection and Quarantine Program, U.S. Forest Service (USFS), Natural Resources Conservation Service (NRCS), U.S. Fish and Wildlife Service (FWS), Bureau of Land Management (BLM), National Parks Service (NPS), U.S. Geological Services (USGS), and U.S. Environmental Protection Agency (EPA). Expertise has been provided to private citizens and to non-profit conservation groups such as Xerces Society for Invertebrate Conservation and North American Pollinator Protection Campaign. With increased focus on native bees, ARS scientists in Logan, Utah have actively collaborated in native bee surveys. For Sub-objective 1.1, significant progress was made using Blue Orchard Bees (BOB) in crop production. Blue orchard bees are often shipped for pollination use to regions that do not match the local climates from which they originated.Understanding how bee origin impacts bee retention in orchards is important for maximizing crop pollination. Most retained bees stayed near a central release site in the orchards and no regular pattern of dispersal to distant sites was shown. This information has led to new management strategies that will mitigate loss of adult BOBs during crop pollination and maximize pollination. In related research, adding BOBs to Washington orchards already stocked with honey bees resulted in higher fruit set just after bloom had ended, than where only honey bees were present. For cherry, fruit set in orchard sections averaged 71% with BOBs present and 51% with only honey bees present. For pears, fruit set with BOBs present averaged 31% and with only honey bees averaged 24%. However, after fruit drop, gains in added fruit set did not result in higher overall yields. In contrast to previous results in cherries, the number of BOBs produced in cherry orchards failed to replace starting populations. To optimize fruit yield, it is necessary to continue to enhance management strategies for orchards. For sustainable bee production for pollination stocks, research is needed on how agronomic practices impact bee reproduction. For commercial production of bumble bees, research examined methods to rear localized species for commercial pollination to help decrease pathogen spill-over from and displacement by species from other regions. For capture of local queens, arboreal nest boxes were tested. In order to maximize mating of future queens, the age at which sperm maturation was reached in drones was determined. Work is initiated on using microcolonies in plant breeding in cages. For Sub-objective 1.2, impact of environmental stress has been investigated. Bees in alpine environments face many challenges, including weather and finding floral hosts. A nine year study in Colorado Rocky Mountains found bee emergence was sensitive to snowmelt timing; but that bee phenology is less sensitive than flower phenology to climatic variation, potentially reducing synchrony of flowers and pollinators under climate change. Large-scale outbreaks of bark beetles resulted in more dead trees but also in increased diversity and number of flowers in the open canopy. Following bark beetle outbreaks, researchers found increased alpine bee diversity. Experiments were continued on impacts of organosilicone spray (OSS) adjuvants. The exposure of bees to OSS and fungicides was examined over time after spray in almonds and levels quantitated. With university collaborators, OSS was found to be taken up by plants. Breakdown of OSS by plants was affected by plant health, with persistence in diseased or stressed plants. Toxicity of insecticides and fungicides increased synergistically when OSS was added. In experiments examining gene expression, OSS was found to decrease expression of genes involved in immunity and anti-viral defenses in honey bees. For Sub-objective 1.3, experiments to examine forage needs of different species of bees and the interactions of the bees were initiated, using honey bee colonies, sentinel colonies of native bumble bees, and Osmia bees. Data to be collected include bee survival and colony growth, source of floral resources, amounts of pollen/nectar being collected, and pathogen detection. Experiments were conducted on bumble bee foraging. For Sub-objective 1.4, research on treatment of pathogens and parasites continues. Alfalfa leafcutting bees (ALCB) are essential pollinators of alfalfa seed crops. A tiny parasitic wasp (Melittobia) has disrupted managed ALCB incubation with devastatingly high losses of bee stocks. Experiments demonstrated that wasps continuously move from one cell to another and able to parasitize 90% of bee cells within 9 days. Trials showed that Melittobia fail to develop at low temperatures, suggesting that parasitism rates could be slowed or negated if managers can place ALCBs into cold storage as soon as bees have reached critical overwintering late larval stages. For ALCB, research was performed to ask how disinfecting agents (hypochlorous acid) can control chalkbrood and other diseases. The hypochlorous acid did not control chalkbrood but did improve survival of eggs and larvae, suggesting that other pathogens or factors are affected that may cause “pollen ball”. Samples have been collected to identify potential pathogens. For Sub-objective 1.5, towards defining pathogens and their identifications, the microbiomes of two Osmia species have been determined, using bees co-reared under identical conditions in a variety of environments. The microbiomes differed by species and were also affected by locality. Two potential pathogens were identified. Efforts are underway to determine if bumble bee frass can be used to monitor pathogens in colonies, to avoid killing bees. For Sub-objective 2.1, much research has been performed. A number of non-native bee species in the family Megachilidae have become established in the United States and present threats to bee pollination in agricultural and natural ecosystems. Detecting exotic bees at ports of entry is needed and challenging given the large number of species. ARS researchers and collaborators in Logan, Utah have developed an illustrated, interactive, web-based guide (Exotic Bee ID) to the bee genera of Megachilidae that allows APHIS inspectors to identify bee genera and determine if they are exotic or native species. A greatly expanded 2nd edition was released. Because a significant number of native bees found throughout the United States belong to this family, the guide will be of use to pollination researchers, land managers, and interested naturalists to identify native bees. The mason bee subgenus Osmia includes several solitary bee species (mason bees) that are managed for orchard and fruit pollination in the United States. Using genomic sequence data, ARS researchers and academic collaborators from Europe and Asia have created a phylogeny of the subgenus Osmia. The results found problems with the identification of several species, including an invasive species introduced into the United States, indicating a need for research to determine the source of introduction. This work provides a strong framework that will inform future ecological, agricultural, and conservation-related investigation into Osmia. Bees are a diverse and important group of insects for the pollination of flowering plants in agricultural and natural ecosystems. Despite their importance, uncertainty exists as to when bees originated and who their closest relatives are. Using genomic sequence data and a diverse sampling of related wasps, ARS researchers and colleagues have identified a small group of wasps that feed on flower-feeding insects as the closest relatives of bees. This research provides important information on bee diversity. Also for Sub-objective 2.1, the Mojave Poppy Bee was found pollinating the rare Dwarf Bear Poppy (Arctomecon humilis) in Utah and later in 1995 in Nevada on the rare poppy Arctomecon californica. Research indicated that this was a specialist bee performing the pollination of these rare plants. Since 1995, populations of Mojave poppy bees appear to have experienced severe declines in Utah. Four surveys for this bee on dwarf bear poppy in Utah lacked detection and resulted in the conclusion that the bee may be locally extinct in Utah. Surveys in 2020 at multiple sites in Nevada documented the Mojave Poppy Bee on multiple populations of the rare A. californica, suggesting this specialist bee is still providing pollination services essential for survival of these endemic plants in Nevada.

Accomplishments
1. Use of blue orchard bees plus honey bees as cherry and pear pollinators increases fruit set, but not final yield. Adding blue orchard bees (BOBs) to Washington orchards already stocked with honey bees resulted in higher fruit set just after bloom had ended, than where only honey bees were present. For cherry, fruit set in orchard sections averaged 71% with BOBs present and 51% with only honey bees present. Likewise for pears, fruit set with BOBs present averaged 31% and with only honey bees averaged 24%. However, after fruit drop later in the summer and at final harvest, the gains in added fruit set did not result in higher overall yields. To optimize fruit yield, it will be necessary to continue to enhance management strategies for both the bees and the orchards.

2. Alfalfa leafcutting bee stocks can be devasted by exponential spread of tiny parasitic wasp Melittobia. Alfalfa leafcutting bees are essential pollinators of alfalfa seed crops and other crops, including canola and blueberries. A tiny parasitic wasp (Melittobia) has disrupted managed ALCB incubation with devastatingly high losses of bee stocks. To ask how the wasp can kill the entire stock of incubating bees, one parasitized cell that produced 30-200 female wasps was placed with 100 cells containing healthy larvae and resulted in more than 90% of the bees being parasitized. Wasps were shown to continuously move from one cell to another. Trials showed that Melittobia fail to develop at low (12°C) and high (>35°C) temperatures, suggesting that parasitism rates could be slowed or negated if managers can place ALCBs into cold storage as soon as bees have reached critical overwintering late larval stages.

3. Exotic bee identification tool aids in detecting invasive bees. The second edition of the Exotic Bee ID was released in March 2020 and significantly expands the use of this tool for identification of exotic and introduced bee species in the United States. A number of non-native bee species in the family Megachilidae have become established in the United States and present threats to bee pollination in agricultural and natural ecosystems. Detecting exotic bees at ports of entry is needed and is challenging because there are an estimated 20,000 species of bees in the world. ARS researchers and collaborators in Logan, Utah, have developed an illustrated, interactive, web-based guide to the bee genera of Megachilidae that allows APHIS inspectors to identify bee genera and determine if they are exotic or native species. The new edition presents four new Lucid keys for subgenera and species of carder bees (Anthidium) and mason bees (Osmia), 96 new fact sheets for subgenera and species of Anthidium and Osmia, and over 800 images for the new taxa. Because a significant number of native bees found throughout the United States belong to this family, the guide will be of use to pollination researchers, land managers, and interested naturalists in identifying their native bees.

4. Climate change and bark beetle outbreaks affect alpine bee communities. Bees in alpine environments face many challenges, including weather and finding floral hosts. Climate change can disrupt plant-pollinator systems through a temporal mismatch, if bees and flowering plants differ in their phenological responses to warming temperatures. While the cues that trigger flowering are well understood, little is known about what determines bee phenology. A nine-year study in the Colorado Rocky Mountains found that bee emergence was sensitive to snowmelt timing, but that bee phenology was less sensitive than flower phenology to climatic variation, potentially reducing synchrony of flowers and pollinators under climate change. Large-scale outbreaks of bark beetles result in more dead trees but also in increased diversity and number of flowers in the open canopy. Following bark beetle outbreaks, researchers found that alpine bee diversity and numbers increased, suggesting that outbreaks may aide in conservation of pollination in forests.

5. Understanding retention and dispersal of blue orchard bees in cherry orchards informs management decisions. Blue orchard bees (BOBs) are often shipped for pollination use to regions that do not match the local climates from which they originated. Understanding how bee origin impacts bee retention in orchards is important for maximizing crop pollination. California- and Utah-sourced bees were flown in California cherry orchards in March and in Utah orchards in May. Bees from Utah remained at orchard nesting sites significantly more than those from California when in California cherries, but bees from both states were retained equally in Utah cherries. Most retained bees stayed near a central release site in the orchards and no regular pattern of dispersal to distant sites was shown. This information was used to develop new management strategies that will mitigate loss of adult BOBs during crop pollination and maximize pollination.

6. Improved systematics and identification of the agriculturally important mason bee subgenus Osmia. The mason bee subgenus Osmia includes several solitary bee species (mason bees) that are managed for orchard and fruit pollination in the United States and other species that have been introduced into areas outside their native ranges. In the United States, several of Osmia species have increased use as major pollinators in commercial agriculture and need to be conserved. Despite the importance of this widely distributed group, few studies have examined its systematics in a comprehensive way. Using genomic sequence data, ARS researchers in Logan, Utah, and academic collaborators from Europe and Asia have created the most complete phylogeny of the subgenus Osmia to date, identifying relationships among the 29 known species with high confidence. The results also found problems with the previous identification of several species, including an invasive species introduced into the United States, indicating a need for future research to determine the country of origin for the introduction and to block additional introductions. This work demonstrates the power of genome-scale data to resolve phylogenetic relationships in bees and provides a strong framework that will inform future ecological, agricultural, and conservation-related investigation into Osmia.

7. Persistence of the rare Mojave Poppy Bee (Perdita meconis), a pollinator of Bear Poppies (Arctomecon humilis and A. californica), documented. The Mojave Poppy Bee was first described in 1993 after being found pollinating the rare Dwarf Bear Poppy (Arctomecon humilis) in Utah and later in 1995 in Nevada on the rare poppy Arctomecon californica. Research indicated that this was a specialist bee performing the pollination of these rare plants. Since 1995, populations of Mojave poppy bees appear to have experienced severe declines in Utah. Surveys for this bee on dwarf bear poppy in Utah in 2012, 2016, and 2017 yielded no P. meconis bees. This lack of detection has resulted in the conclusion that this species may be locally extinct in Utah. Surveys in 2020 at multiple sites in Nevada documented the presence of the Mojave Poppy Bee on multiple populations of the rare Arctomecon californica, suggesting that this specialist bee is still providing pollination services essential for survival of these endemic plants in Nevada.

8. New insight into the determinants of the microbiome of solitary bees. Managed pollinators such as the mason bees like Osmia lignaria and O. ribifloris are essential to the production of a wide variety of agricultural crops. These pollinators encounter a diverse array of microbes when foraging for food and nest-building materials on various plants. To ask how microbiome composition was determined by species and environment, ARS scientists and collaborators reared up both species in the same environments, including a containment screenhouse. Both species and environment affected the bacterial and fungal species in the microbiome, suggesting that the bee could affect its offspring’s microbiome. Potential bee pathogens were identified.

9. New insights into the origins of bees and role in pollination. With over 20,000 species known, bees are one of the most diverse and important groups of insects for the pollination of flowering plants in agricultural and natural ecosystems. Despite their importance, uncertainty exists as to when bees originated and who their closest relatives are and this information could provide insights into what makes bees special and great pollinators. Using genomic sequence data and a diverse sampling of related wasps, ARS researchers and colleagues have identified the closest relatives of bees with high confidence, revealing them to be a small group of wasps that feed on flower-feeding insects. This research provides important information on bee diversity and will help researchers understand what makes a bee different from a non-bee as a pollinator and aide in conserving bee species.

Review Publications
Boyle, N.K., Artz, D.R., Lundin, O., Ward, K., Picklum, D., Wardell, G., Pitts Singer, T. 2020. Wildflower plantings promote blue orchard bee, Osmia lignaria (Hymenoptera: Megachilidae), reproduction in California almond orchards. Ecology and Evolution. 10(7):3189-3199. https://doi.org/10.1002/ece3.5952.
Boyle, N.K., Pitts Singer, T. 2019. Assessing blue orchard bee (Osmia lignaria) propagation and pollination services in the presence of honey bees (Apis mellifera) in Utah tart cherries. PeerJ. https://doi.org/10.7717/peerj.7639.
Grab, H., Branstetter, M.G., Amon, N., Blitzer, E.J., Gibbs, J., Park, M. 2019. Agriculturally dominated landscapes reduce bee phylogenetic diversity and pollination services. Science. 363(6424):282-284. https://doi.org/10.1126/science.aat6016.
Longino, J.T., Branstetter, M.G. 2020. Phylogenomic species delimitation, taxonomy, and "bird guide" identification for the Neotropical ant genus Rasopone (Hymenoptera: Formicidae). Insect Systematics and Diversity. 4(2). https://doi.org/10.1093/isd/ixaa004.
Smith, A.M., Hallwachs, W., Janzen, D., Longino, M., Branstetter, M.G. 2020. A subterranean ant (Acanthostichus (Mayr 1887)) revealed in Costa Rica. Insectes Sociaux. 67:327–330. https://doi.org/10.1007/s00040-020-00754-9.
Cane, J.H., Love, B.G. 2018. Mortality and flowering of great basin perennial forbs after experimental burning: implications for wild bees. Rangeland Ecology and Management. 41(2):124-127. https://doi.org/10.1016/j.rama.2018.11.001.
Meiners, J.M., Griswold, T.L., Messinger-Carril, O. 2019. Decades of native bee biodiversity surveys at Pinnacles National Park highlight the importance of monitoring natural areas over time. PLoS ONE. 14(1): e0207566. https://doi.org/10.1371/journal.pone.0207566.
Portman, Z.M., Burrows, S.J., Griswold, T.L., Arduser, M., Irber, A., Tonietto, R.K., Cariveau, D.P. 2019. First records of the adventive Pseudoanthidium nanum (Moscáry) (Hymenoptera: Megachilidae) in Illinois and Minnesota, with notes on its identification and taxonomy. Great Lakes Entomologist. 52(1):12-20.
Portman, Z.M., Orr, M.C., Griswold, T.L. 2019. A review and updated classification of pollen gathering behavior in bees (Hymenoptera: Apoidea). Journal of Hymenoptera Research. 71:171-208. https://doi.org/10.3897/jhr.71.32671.
Kazenel, M.R., Wright, K.W., Bettinelli, J., Griswold, T.L., Whitney, K.D. 2020. Predicting changes in bee assemblages following state transitions at North American dryland ecotones. Scientific Reports. 10. https://doi.org/10.1038/s41598-020-57553-2.
Pitts Singer, T. 2020. Photoperiod effect on Megachile rotundata (Hymenoptera: Megachilidae) female regarding diapause status of progeny: the importance of data scrutiny. Environmental Entomology. 49(2):516–527. https://doi.org/10.1093/ee/nvaa004.
Tian, L., Rahman, S., Ezray, B., Franzini, L., Strange, J.P., Lhomme, P. 2019. A homeotic shift late in development drives mimetic color variation in a bumble bee. Proceedings of the National Academy of Sciences. 116(24):11857-11865. https://doi.org/10.1073/pnas.1900365116.