Location: Pollinating Insect-Biology, Management, Systematics Research
2025 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 is the final report for Project 2080-21000-019-000D Sustainable Crop Production and Wildland Preservation through the Management, Systematics, and Conservation of a Diversity of Bees, which has been replaced by new project 2080-30500-001-000D Management, Conservation, Systematics, and Genomics of Diverse Bees for Sustainable Crop Production and Wildlands Preservation in a Changing Climate. For additional information, see new project report.
Of the 20,000 bee species worldwide, few are managed to pollinate agricultural crops; although, pollination by native species benefits crop yield. ARS scientists in Logan, Utah, did research to: (1) Improve crop pollination by non-Apis bees by identifying factors impacting bee health and develop bee management strategies to ensure pollinator populations; (2) Improve bee systematics and develop new tools for bee identification for understanding of wild bee diversity and presence. Research was reported to the public, alfalfa seed producers, almond growers, fruit growers, bee producers, honey bee keepers, and agencies such as: Animal and Plant Health Inspection Service (APHIS), 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).
For Sub-objective 1.1, research was carried out for almond, cherry, pear, berry, and alfalfa seed crops. Three mason bee species (Osmia lignaria, O. ribifloris, and O. bruneri) were tested as managed pollinators in berry crops. O. ribifloris should be explored as a managed pollinator for blueberry pollination and O. bruneri for pollination of currants.
Significant progress was made using Blue Orchard Bees (BOB, or Osmia lignaria) in crop production. BOBs were demonstrated to adapt to warming environments, with better reproduction and greater efficiency in almond pollination when acclimated. BOB release into orchards was detailed in best management practices to maximized pollination. Adding BOBs to cherry and pear orchards stocked with honey bees resulted in higher fruit set. Surveys of Washington State Fruit growers indicate a desire to use BOBs.
Sub-objective 1.2 focused on Organosilicone spray (OSS) adjuvants, which are widely used in tank mixes and have been detected in pollen. OSS adjuvants were found to negatively impact egg laying by honey bee queens and increase titers of Deformed Wing Virus in workers. ARS researchers and collaborators, found OSs to be taken up by plants and detected in all plant tissues. Toxicity of insecticides and fungicides in adult honey bees increased synergistically with added OSS. In honey bees OSS exposure decreased expression of immunity and anti-viral defenses genes. OSS at moderate doses caused death of early instar larvae when fed in pollen to BOBs. OSS increased titers of Apis mellifera filamentous virus with increased mortality.
Collaborations with Utah State University (USU) revealed how pesticides move from soil or leaf pieces into pollen provisions. Data will allow parameters to be incorporated into models used by EPA for risk assessment.
With collaborators, pesticides were measured in bee-collected pollen in blueberry and alfalfa seed pollination. In blueberry pollen from honey bees and bumble bees, 80 pesticides were detected with an average of 22 pesticides per sample, even on farms with no pesticide applications. For alfalfa pollen and soil taken from alkali bee nests, pesticides not actively applied were detected in the soil. These data give evidence of widespread pesticide exposure at a landscape level.
Chemical control with minimal pollinator impacts is needed for pests in alfalfa seed crops. The safety of two insecticides (afidopyropen and sulfoxaflor) used during bloom for Lygus bug control was tested on alfalfa leafcutting bees (ALCB). Afidopyropen had no measurable effects. Sulfoxaflor increased bee mortality and should be used with caution during bloom.
Experiments focued on Sub-objective 1.3, examined forage needs and interactions of bees, using honey bee colonies, sentinel colonies of native bumble bees, and solitary Osmia bees. Solitary bees do well when given a single floral resource; however, both honey bees and bumble bees required multiple floral resources for colony survival. The amount of floral resources was important. With limited flowers, competition resulted with negative impacts on all three types of bees; but no negative interactions on flowers were observed.
For alfalfa seed production, coordinating bee emergence with alfalfa bloom is critical; weather conditions can cause bee managers to hold ALCB while waiting for plants to bloom. Feeding bees honey-water for five days or less assures the bees will perform pollination well, but performance was best when bees could be directly released.
For Sub-objective 1.4, ALCB are essential pollinators of alfalfa seed crops and a tiny parasitic wasp (Melittobia) has disrupted managed ALCB use with high losses of bee stocks. New best management practices for control were developed. Molecular genetics were done on the wasp, resulting in a definitive ID as M. acasta. The life cycle was fully detailed.
For Sub-objective 1.5, diapausing adults of O. lignaria were found to be infected with multiple species of microsporidia, with sequences similar to Nosema ceranae and to unknown microsporidia species. Molecular analyses with primers for multiple genes of N. ceranae found the microsporidian in BOBs was related to N. ceranae but not the same species, indicating that spillover of N. ceranae from honey bees to O. lignaria via feces on flowers does not occur.
Prevalence and titers of ssRNA viruses in honey bee colonies decreased when they moved from almond orchards into a Utah forest. All colonies were infected with a DNA virus (Apis mellifera filamentous virus, AmFV) at high levels. In bumble bee colonies, ssRNA viruses were not associated with colony death nor impacts on queen production. The AmFV virus was in newly emerged queens and highly correlated with death of bumble colonies. The solitary bee Osmia lignaria cleared all ssRNA viruses at metamorphosis, without any impacts. AmFV was found in wild populations of O. lignaria and caused death when fed to larvae.
For Sub-objective 2.1, PIBMSRU is home of the U.S. National Pollinating Insect Collection (NPIC), a world-class research collection of bees with over 2.4 million specimens and an associated database with specimen information, including plant/pollinator associations and a database is being added to the ARS Biocollections website, which will be searchable for occurrence and distribution of bee species, making data available to others.
ARS scientists and collaborators improved bee identification and phylogeny using genomic methods. Species were added to the library of DNA barcodes for U.S. bees; a low-cost protocol for barcoding was created.
The “Beenome100” research will produce high-quality genomes of more than 100 species, capturing the diversity of U.S. bees. ARS researchers at Logan, Utah are joining other ARS and university researchers to perform this research, by guiding species selection, specimen collection, and genomic data analysis. For these essential pollinators of agriculture and natural ecosystems, more than 100 genomes have been completed.
For bumble bee species of concern, museum specimens were used to create high-quality genomes for Franklin’s bumble bee, the rusty-patch bumble bee and the western bumble bee. Additional studies for the western bumble bee found recent declines in genetic diversity. Collaborative research linked the decline of this bee to climate change and pesticide exposures. A collaborative study on population genetics of rusty patched bumble bees found that genetic diversity varied by location, providing context for potential risks of translocation programs.
In collaboration with Kansas State University, ARS researchers helped develop methods in artificial intelligence (AI) to perform species-level bee identification from images to increase the utility of the “Bee Machine” app that can identify all U.S. bumble bee and other bee species.
To protect existing pollinators and pollination in agricultural and natural ecosystems, detection of invasive bees at ports of entry is needed. With collaboration, an interactive, web-based guide (Exotic Bee ID) to the bee genera of Megachilidae and other genera was developed and allows APHIS inspectors and others to identify bee genera and determine invasive status.
The classification and phylogeny for several groups of bees have been revisited. For the long-horned bee tribe Eucerini, genomic data from over 153 species was used to examine taxonomy, phylogeny, and biogeography. The group are pollinators of agriculturally important plants, such as squash and relatives. With genomic sequence data, a phylogeny of the subgenus Osmia was created. For the cleptoparasitic genus Nomada, a molecular phylogeny was performed on the 800 species globally, including 265 species in U.S. This genus is commonly collected and a proxy for bee diversity because of its reliance on other bees for reproduction.
The Mojave Poppy Bee pollinates the rare poppies Arctomecon humilis and A. californica and maybe extinct in Utah. The bee was found in 2020 in Nevada but not found under extreme drought in 2021 and 2022. In 2023 with abundant precipitation, the species was found again. This raises the question of how the bee species can undergo extended diapause and emerge when weather is favorable. For the poppies, multiple species of bees visited and all seeds fully developed.
To understand the impact of honey bee apiaries on native bees, controlled experiments were performed in the Uinta-Wasatch-Cache National Forest. Honey bee apiaries had no negative impacts on reproduction, survivorship, nor floral choice of other bee species.
Accomplishments
1. Pollinator plantings adjacent to blueberry fields do not reduce pesticide exposure in bees. Wildflower pollinator plantings installed to support wild bees adjacent to blueberry fields in Michigan were evaluated for their role in reducing pesticide exposures in wild bees. A research team led by an ARS researcher in Logan, Utah, found that presence of pollinator plantings did not reduce pesticide exposure in bumble bee collected pollen compared to sites without pollinator plantings. Wildflowers in plantings were contaminated with pesticides, sometimes at high levels, due to pesticide drift. These results provide evidence to growers, pesticide applicators, regulators, and researchers that pollinator plantings adjacent to agricultural fields can be sources of high-risk pesticide exposures for wild bees, and mitigation measures to reduce pesticide drift are needed. For growers that depend upon bee pollination for crop production, this is critical information.
2. Combined use of the blue orchard bee and honey bees in pear and cherry orchards results in increased yield, even in bad weather. Pollination of sweet cherries and pears can be difficult with unpredictable spring weather. ARS researchers in Logan, Utah, found that when blue orchard bees were added to honey bees in sweet cherry and pear orchards in Washington state, pollination efficacy increased by 12%. These results positively impact cherry and pear growers, especially those in Washington state or other areas where spring weather has become variable and cold snaps are common. The blue orchard bee flies at much cooler temperatures than honey bees, therefore acting as an added pollination insurance for the orchard growers.
3. Genomic data resolve species boundaries in the western bumble bee, a species of conservation concern. The western bumble bee, Bombus occidentalis, was once widespread in the western United States, but in the 1990s the species underwent a large decline. This bee is currently being considered for listing under the endangered species act. Uncertainty exists as to whether B. occidentalis is composed of one, two, or more species, making it hard to establish conservation targets. ARS researchers at Logan, Utah, in collaboration with university scientists, used genomic data to test species boundaries in B. occidentalis and found support for the existence of two, geographically separated species, B. mckayi in the north (Canada to Alaska), and B. occidentalis in the south (Canada and the contiguous United States). Both species occur in the United States and will need to be separately assessed for their conservation status. This data will support regulatory agencies and conservation measures.
4. Honey bees do not negatively impact other bee species when colony numbers do not exceed the amount of available floral resources. Honey bees have been in North America for more than 500 years and are critical pollinators for many crops, given the ability to move colonies into crops like almonds and fruit for pollination. Controversy about negative impacts of honey bees on other bee species caused stakeholders to ask for research to thoroughly investigate potential impacts of honey bee colonies on reproduction, interactions with floral hosts, and impacts of disease in other bee species. ARS researchers in Logan, Utah conducted a controlled experiment with sentinel bumble bee colonies, solitary bees, and honey bees. In cages with limited floral resources, competition did impact all three types of bees equally. No negative interactions were observed on flowers. In the field, presence of 48 colonies of honey bees did not impact reproduction of bumble bees nor solitary bees. No negative impacts of disease transmission were found among the three types of bees. Conclusions were that the amount of floral resources or carrying capacity was critical in determining how many honey bee colonies could be supported without negative impacts on other bee species. Other factors such as climate (drought and heat) and other uses (grazing by cows or sheep) need to also be considered, given impacts on floral resources. This data is important for land managers, growers, and bee keepers; each want to conserve bee species for pollination.
5. Reproduction of solitary bees is greatly impacted by extreme drought. The western United States has been greatly impacted by increased drought and hot weather. ARS researchers in Logan, Utah, conducted experiments for three years monitoring reproduction of a solitary bee (Osmia bruneri) that nests in cavities. During the three years, drought ranged from moderate, to severe, to extreme. During the extreme years with decreased floral resources, the female bees reproduced significantly less, forming fewer nest cells. Significantly, the sex ratio (how many females versus males) greatly shifted also, going from a 1:1 ratio of females to males to a 1:3 ratio (one female per 3 males). This resulted in many fewer female bees for pollination in the next season; and this observation may explain significant population decreases being observed for some species. This impact of climate change is of concern, given the role of solitary bees in pollination or plant reproduction for crops and plants in natural ecosystems. This information is required by land managers, conservation biologists, and growers.
6. Insights into the Mojave Poppy Bee populations and the Las Vegas bear poppy, as a possible threatened species. The Mojave Poppy Bee, a rare bee of the eastern Mojave Desert, is being considered to be listed as a threatened species. Fieldwork in 2024 by ARS researchers in Logan, Utah, concluded five years of searching for this bee. The bee remains present in many historic locations but not all. The appears now to be extinct in southwestern Utah. This bee requires rare bear poppies or prickly poppies for food for its offspring. These plants only live for a few years so they are not always found at known locations. This research also found that this bee can remain as an immature larva for at least three years, presumably to wait for good conditions. A reference genome was constructed for Mojave Poppy Bee, as part of the congressionally-mandated Beenome 100 project. The reference genome is the first for a major lineage of bees and it will serve as an important tool for assessing the conservation status of P. meconis. No evidence of pollination limitation was detected for the bee’s host plant, the Las Vegas bear poppy, Arctomecon californica, a rare plant that is pollinator dependent for reproduction. Populations of the plant fluctuate year to year. ARS researchers in Logan, Utah, documented wild bee visitations and seed production at eight poppy populations in 2022 and 2023. No evidence was found for reproduction of these poppies being pollination limited. The poppies had high rates of seed production, even in a severe drought year with lower bee activity. These results are being used by the U.S. Fish and Wildlife Service in their species status assessment in considering an endangered species listings for the Las Vegas bear poppy and the Mojave Poppy Bee.
7. Insight into the biology of the Hunt bumble bee, a pollinator of agricultural importance, by development of a high-quality genome. The Hunt bumble bee is an important pollinator found widely in western North America. To learn more about its biology and help with studies on its populations and breeding, ARS researchers in Logan, Utah, Hilo, Hawaii, and Stoneville, Mississippi, decoded the entire genetic code of a single male bee. Using advanced sequencing technologies, the ARS researchers put together a detailed map of its genome with high accuracy. This map shows how the bee's genetic material is organized into 18 chromosomes, covering a total of 317.4 million base pairs. This analysis indicates that over 97.6% of the genome is complete and correctly arranged. Importantly, the methods employed by the ARS researchers achieved high-quality genome assembly through efficient methods for studying and understanding genomes. This research benefits others wanting to create genomic information or protecting this bee’s health for pollination of crops and other plants.
8. New method of evaluating floral resources for plant management and pollinator health. Diverse flowers are needed to support healthy pollinator populations and important for plant reproduction. Traditional ways of counting flowers take a lot of time and people. Especially in large areas, these methods might miss changes in where and when flowers grow. Unmanned aerial vehicles (drones) can now be used to determine the distribution of flowers across big areas. ARS researchers in Logan, Utah, used pictures from drones and a machine learning algorithm to count flowers in places like fields and forests, where land shapes, plants, and flower sizes change. The ARS researchers found seven types of flowers covering 2,138 square meters, which is 0.5% of the whole area studied. The researchers figured out when flowers bloom by looking at how flower areas changed in the pictures. These models worked well even though there were very few flowers in the unmanned aerial vehicles pictures. This method of using images from drones to determine the diversity and number of flowers resources will greatly aide in management of lands to support healthy pollinators and plants by beekeepers, growers, and land managers.
9. Insight into world-wide distribution of bee species via a new dataset. Specific information on where organisms such as bees have been found is essential for scientific research and communication, yet gathering these records from multiple sources is a major accessibility issue. ARS researchers in Logan, Utah, and with collaboration by university scientists, created a new global bee occurrence dataset, providing data on distribution, seasonality and floral relationships. Existing bee occurrence data were merged and standardized from major data repositories and private datasets using a reproducible R-workflow. The data set gives a common taxonomic name, location, and collection date. The computer code used to merge, edit, flag, and filter the data are provided, allowing for periodic updates. This tool will be invaluable to researchers, land managers, and growers wanting pollination of specific crops.
Review Publications
Chanprame, S., Meidt, C., Griswold, T.L., Wilson, J.S., Graham, K.K. 2024. Chasing a little-known fairy bee (Perdita meconis) in a dynamic desert landscape. Insects. 15(11). Article 892. https://doi.org/10.3390/insects15110892.
de Pedro, D., Ceccarelli, F.S., Sagot, P., Lopez-Reyes, E., Mullins, J., Merida-Rivas, J., Falcon-Brindis, A., Griswold, T.L., Ascher, J.S., Gardner, J., Ayala, R., Vides-Borrell, E., Vandame, R. 2024. Revealing the Baja California Peninsula’s hidden treasures: An annotated checklist of the native bees (Hymenoptera: Apoidea: Anthophila). Zootaxa. 5522(1):1-391. https://doi.org/10.11646/zootaxa.5522.1.1.
Schweizer, R.M., Meidt, C.G., Benavides, L., Wilson, J.S., Griswold, T.L., Sim, S.B., Geib, S.M., Branstetter, M.G. 2023. Reference genome for the Mojave poppy bee (Perdita meconis), a specialist pollinator of conservation concern. Journal of Heredity. 115(4):470-479. https://doi.org/10.1093/jhered/esad076.
Graham, K.K., Milbrath, M.O., Killewald, M., Soehnlen, A., Zhang, Y., Isaacs, R. 2023. Identity and diversity of pollens collected by two managed bee species while in blueberry fields for pollination. Environmental Entomology. 52(5):907-917. https://doi.org/10.1093/ee/nvad072.
Warrit, N., Ascher, J., Basu, P., Belavadi, V., Brockmann, A., Buchori, D., Dorey, J.B., Hughes, A., Krishnan, S., Koch, J., et al. 2023. Opportunities and challenges in Asian bee research and conservation. Biological Conservation. 285. Article 110173. https://doi.org/10.1016/j.biocon.2023.110173.
Almeida, E.B., Bossert, S., Danforth, B.N., Porto, D.S., Freitas, F.V., Davis, C.C., Murray, E.A., Blaimer, B.B., Spasojevic, T., Stroher, P., Orr, M.C., Packer, L., Brady, S.G., Kuhlmann, M., Branstetter, M.G., Pie, M.R. 2023. The evolutionary history of bees in time and space. Current Biology. 33(16):3409-3422.e6. https://doi.org/10.1016/j.cub.2023.07.005.
McCabe, L.M., Chesshire, P., Cobb, N.S. 2023. Forest habitats and plant communities strongly predicts Megachiladae bee biodiversity. Diversity and Distributions. 11. Article e16145. https://doi.org/10.7717/peerj.16145.