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

2021 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, Utah, 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. In support of Sub-objective 1.1, significant progress was made using blue orchard bees (BOB) in crop production. The second year of research on pollination with BOBs and honey bees in Washington sweet cherry orchards resulted in higher fruit set just after bloom had ended, than where only honey bees were present. For both 2019 and 2020 seasons, significantly higher fruit set occurred with use of both honey bees and BOBs for pollination. However, after fruit drop, gains in added fruit set did not result in higher overall yields, suggesting that other factors were important in determining fruit yield. To optimize fruit yield, it is necessary to continue to enhance management strategies for orchards. For the 2021 season, additional data is being obtained for both sweet cherries and pears. A pollen analysis of BOB provisions taken from nests made throughout the season, revealed that bees were collecting primarily cherry pollen while the orchard was in bloom. Other pollens being collected came from apple orchards nearby and blooming flowers on ground cover in the orchards. Related to commercial production of bumble bees, research examined the impact of overwintering conditions on Bombus queens from three species. The impact of fluctuating thermal regimes (FTR) versus static thermal treatments (control) was tested in combination with other factors likely to influence cold storage success, including initial weight, foundress colony age, and geographic distribution. Wild queens (B. vosnesenskii and B. huntii) stored in FTR had a lower survival as compared to controls; however, in commercial B. impatiens, queens had a higher survival response to FTR. The queen’s initial weight was positively correlated with longer survival and also linked to post hibernation lipids, which serve as an energy reserve while in cold storage. 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 and OSS was detected in all plant tissues including flowers, fruit, and pollen. 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 the 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 being collected include bee survival and colony growth, floral resources, amounts of pollen/nectar being collected, and pathogen detection. For alfalfa leafcutting bees (ALCB), diets including amino acids and sugars were tested for consumption and impacts on survival of newly emerged bees. Similar to honey bees, ALCB preferred to consume diets with essential amino acids. Those bees consuming a diet of sugar and a mixture of essential amino acids lived significantly longer than bees consuming just sugar water or dilute honey water. Experiments are being conducted to ask how these diets impact metabolism and reproduction of the bees when moved into blooming alfalfa over time, with the goal to allow for growers to maintain bees for pollination if bloom is delayed. In support of Sub-objective 1.4, research on treatment of pathogens and parasites continues. Alfalfa leafcutting bees are essential pollinators of alfalfa seed crops. A tiny parasitic wasp (Melittobia) has disrupted managed ALCB incubation with devastatingly high losses of bee stocks. Even if the wasps occur in a low percent of cocoons, they can move quickly into nearby cocoons and cause high losses. Treatment with dichlorvos strips was done at various timepoints. When pesticide strips were placed into incubating trays at three days, both Melittobia and another parasitic wasp species were largely controlled. A few Melittobia were able to live and emerge with the adult bees, indicating the control of these parasitoids is needed on a regular basis. For Sub-objective 1.5, towards defining pathogens and their identifications, bacterial, protozoan, and microsporidian pathogens of Osmia lignaria from four wild populations were assayed. Few bacterial and protozoan pathogens were detected. A high percentage of diapausing adult bees were infected with at least two species of microsporidia. Sequences confirmed one of the species as Nosema ceranae and the other sequences were microsporidia but did not match known species. Additional research is being done to determine the impacts on bee health and reproduction. Using molecular analyses, the species determination of the parasitoid wasp found in ALCB was made as Melittobia acasta in specimens from multiple growers in different states. Molecular analyses will be used to determine if the wasps are genetically the same in these detections and if the wasps might have come from a common source. Additional research is being performed to ask if the same species is found in other bee species. In support of Sub-objective 2.1, much research has been performed. Several different groups of bees and their classification and phylogeny have been revisited and the work is proceeding. For cleptoparasitic bees in the sub-family Nomadinae, the evolutionary history and systematics were resolved. The data reveal that the parasitic bees transitioned independently two times from closed-cell to open-cell parasitism. The data also revealed that the first hosts were related bees in the family Apidae and the parasitic bees shifted as they speciated to more distantly related bee species. For the genus Nomada, a molecular phylogeny was performed. The bee genus Nomada includes over 800 species globally, including 265 species in the United States, and represents the largest group of brood parasitic bees known. The genus is commonly collected in bee surveys and is of value as a proxy for overall bee diversity because of its reliance on other bees for reproduction. This research provides a sound foundation for the classification of this genus. In addition, the data provide insight into the evolution of this bee group with the genus likely having originated in the northern hemisphere during the late Cretaceous. The data also support the bees as having repeated dispersal across land bridges within the northern hemisphere during their evolutionary history. 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 prior to 2020 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 did find the Mojave Poppy Bee on several populations of the rare poppies. Several male specimens were collected and a genome has been constructed for the bee. In 2021, extensive surveys have been performed in multiple sites in Nevada and in Utah; these areas were under extreme drought conditions. The poppies were found in both states and were being visited by other bee species. However, no Mojave Poppy Bees were detected during the entire season and this species is only known to visit the poppies. In 2022, there are plans to revisit these sites to determine if this bee can be found. Some solitary bees can go through multiple years as diapausing bees, so there is hope that this may be the case and the bee will be detected again.

Accomplishments
1. Modified pest-control method protects alfalfa leafcutting bees from parasitic wasps during incubation. Alfalfa leafcutting bees (ALCB) are important pollinators of alfalfa for seed production. Developing leafcutting bees need to be incubated prior to adult emergence; and parasitic wasps present a danger to the bees. The parasitic wasp Melittobia acasta is especially dangerous when present in less than 1% of the cocoons and is capable of destroying the entire bee population needed for pollination of alfalfa field grown for seed production. ARS scientists in Logan, Utah, found that by adding a dichlorvos insecticide strip at three days into incubation of the bees, several species of parasitic wasps (Pteromalus venustus, and Mellitobia acasta) were killed and unable to attack additional bees. This treatment was much earlier than previously recommended and did not impact the leafcutting bees. This modification is a highly effective and simple strategy to protect the ALCBs and it helps to ensure that the growers can have a healthy population of bees for alfalfa pollination and seed set.

2. Development of method to prevent death of managed bumble bee colonies by a parasitic bee. Commercial bumble bee colonies are used for pollination of several crops in an open setting and are susceptible to invasion and death by a parasitic bumble bee species. Cuckoo bumble bees are a unique lineage of bees that depend exclusively on a host bumble bee species to provide nesting material, nutritional resources, and labor to rear offspring. Invasion by a cuckoo bumble bee typically results in the death of resident bumble bee queen and her offspring. ARS scientists in Logan, Utah, found that survival of deployed bumble bee colonies was greatly affected by cuckoo bumble bees that were present in large numbers. Data from field-deployed bumble bee colonies suggest that colonies with less than 20 workers are highly susceptible to cuckoo bumble bee invasion. A fabricated excluder was designed to prevent the cuckoo bumble bee invasion and was 100% effective at reducing colony loss. The use of the fabricated excluders on colony boxes will protect commercial bumble bee colonies utilized in open field conditions and enable effective delivery of pollination services.

3. Organosilicone spray adjuvants are taken up by plants and moved into flowers and pollen. Healthy pollinators are needed for pollination of agricultural and natural ecosystems. Previous research has found that commonly used organosilicone spray adjuvants (OSS) are toxic to bees and cause sublethal impacts on pathogens and behavior. OSS are commonly added to herbicide and other pesticide applications for a wide variety of uses. Understanding the fate of OSS in the environment is essential to trying to protect pollinators. ARS researchers and collaborators in Logan, Utah, found that OSS is taken up by plant roots, carried throughout the plant, and moved into pollen and fruits. The OSS were found to be broken down into smaller compounds during the process. Additional research is needed to determine if the breakdown components are toxic to bees.

4. Climate change may exacerbate the threat of biological invasions by introduced bee species. Island ecosystems may be particularly sensitive to the combined effects of climate change and biological invasions. In Hawaii, there are 21 non-native bees that have the capacity to spread pathogens and compete for resources with some 60 native bees to Hawaii. ARS researchers in Logan, Utah, modeled the predicted distributions for eight non-native bee species in Hawaii across the islands under current and future predicted climate conditions. Although the models predict expansion of the invasive bees into higher elevations under 2070 climate scenarios, areas below 500 meters in elevation were predicted to maintain their species richness. These models have the capacity to inform management decisions by federal and state stakeholders for non-native bees in Hawaii by assessing risk of invasion into new areas around the archipelago.

5. Incubation of blue orchard bees at constant temperature improves bee survival and coordination with orchard bloom period. Blue orchard bees (BOB) are efficient pollinators of fruit and nut trees blooming in early spring; use of these bees and honey bees can give synergistically higher fruit set for nut and fruit crops. BOBs are collected either from nests of orchards that they pollinated or from nests in natural habitats. ARS researchers in Logan, Utah, found that the development and survival of the bees was improved when nests with developing bees were kept at constant temperature versus at fluctuating natural temperatures. Having the bees at constant temperature prior and during overwintering allowed for optimization of bee emergence in coordination of bloom in early spring crops. This information will allow fruit and nut growers to have more effective pollination of their crops.

6. Honey bee hives can serve as incubators to help blue orchard bees (BOBs) emerge from cocoons in the field. Blue Orchard Bees (BOB) are an effective pollinator of early season fruit and nut crops, especially when used in combination with honey bees. The “hivetop” incubator (HTI) was designed and patented by collaborators, as a product to allow for the timely release of BOBs to pollinate spring orchard crops. Reluctance to use these HTIs has been based on an unfounded concern for the health of honey bee colonies that produce the heat which stimulates BOBs emergence. ARS scientists in Logan, Utah, found that HTIs provide for a quick and efficient emergence of BOBs with no loss of heat from the interior of honey bee hives. Honey bee colonies with or without the HTIs remained equally healthy with no impacts found on the queen, worker, and brood loss over the subsequent season. This demonstrated that the use of HTIs provides growers or bee keepers a way to easily manage BOBs for pollination events, providing added confidence in getting fruit set.

7. Extreme weather conditions negatively impact wild bees at blueberry farms. Wild bees are responsible for 10-80% of pollination on highbush blueberry farms, depending on the farm size. An ARS researcher in Logan, Utah, and collaborators analyzed over 15 years of data to find a significant decline and then partial recovery in wild bee abundance and species richness following extreme spring weather. In 2012, unusually high temperatures in early spring led to a very early bloom of spring plants and crops and early emergence of bees. Freezing temperatures in April and May, which are typical for the region, were then incredibly damaging to sensitive blooming crops such as blueberry, which usually aren’t subject to spring freezes. The damage to flowers was followed by large reductions in the populations of several species of wild mining bees the next year. Understanding the impacts of climate change on native bees is important in planning for the need for managed pollinators in blueberries.

8. New insights into the systematics and evolution of brood parasitic bees (Apidae: Nomadinae). Brood parasites (also known as cleptoparasites) represent a substantial fraction of global bee diversity, with the oldest and most speciose parasitic group being the subfamily Nomadinae. Despite significant interest, family relationships among brood parasitic species both within and outside the Nomadinae have not been well studied. Using genomic sequence data, ARS researchers in Logan, Utah, and academic collaborators from the United States and Europe, conducted the most comprehensive genetic analysis of this bee group to date, identifying family relationships and evolutionary patterns among 114 species. The study used the results to improve the taxonomy of Nomadinae bees and to examine the evolution of host-parasite associations in the group. This work enhances communication about Nomadinae bees and provides a strong framework for future ecological, agricultural, and conservation-related research.

9. Improved knowledge about the parasitic bee genus, Nomada. The parasitic bee genus, Nomada, includes over 800 species globally, including 265 species in the United States. This group of bees are parasitic on ground-nesting solitary bees and are commonly collected in bee surveys. Despite the importance of Nomada to bee conservation and biodiversity research, identifying and determining the relatedness of these bees has been challenging. Using genomic-scale molecular sequence data and extensive species sampling, ARS researchers in Logan, Utah, and Canadian collaborators have made the first extensive molecular study of relationships for this genus. The results have revealed new insight into the species and found that the genus likely originated in the northern hemisphere, a scenario that contradicts previous suggestions. This work advances understanding of the biodiversity of Nomada bees and provides a useful foundation for their identification and additional research.

Review Publications
Bossert, S., Copeland, R.S., Sless, T.J., Brady, S.G., Danforth, B.D., Branstetter, M.G., Gillung, J., Straka, J. 2020. Phylogenomic and morphological reevaluation of the bee tribes Biastini, Neolarrini, and Townsendiellini (Hymenoptera: Apidae) with description of three new species of Schwarzia. Insect Systematics and Diversity. 4(6). https://doi.org/10.1093/isd/ixaa013.
Branstetter, M.G., Muller, A., Griswold, T.L., Orr, M.C., Zhu, C. 2021. Ultraconserved element phylogenomics and biogeography of the agriculturally important mason bee subgenus Osmia (Osmia). Systematic Entomology. 46(2):453-472. https://doi.org/10.1111/syen.12470.
Freitas, F.V., Branstetter, M.G., Griswold, T.L., Almeida, E.A. 2020. Partitioned gene-tree analyses and gene-based topology testing help resolve incongruence in a phylogenomic study of host-specialist bees (Apidae: Eucerinae). Molecular Biology and Evolution. 38(3):1090-1100. https://doi.org/10.1093/molbev/msaa277.
Davis, T.S., Rhoades, P.R., Mann, A.J., Griswold, T.L. 2020. Bark beetle outbreak enhances biodiversity and foraging habitat of native bees in alpine landscapes of the southern Rocky Mountains. Scientific Reports. 10: Article 16400. https://doi.org/10.1038/s41598-020-73273-z.
Cane, J., Gardner, D.R., Weber, M. 2020. Neurotoxic alkaloid in pollen and nectar excludes generalist bees from foraging at death-camas, Toxicoscordion paniculatum (Melanthiaceae). Biological Journal of the Linnean Society, London. 131(4):927-935. https://doi.org/10.1093/biolinnean/blaa159.
Delphia, C.M., Griswold, T.L. 2021. First records, phenology, habitat, and host-plant associations of Macrotera opuntiae (Cockerell) (Hymenoptera: Andrenidae) in Montana. Journal of Melittology. (102):1-10. https://doi.org/10.17161/jom.i102.13700.
Murray, E., Evanhoe, L., Bossert, S., Geber, M.A., Griswold, T.L., McCoshum, S.M. 2021. Phylogeny, phenology, and foraging breadth of ashmeadiella (Hymenoptera: Megachilidae). Insect Systematics and Diversity. 5(3). https://doi.org/10.1093/isd/ixab010.
Klinger, E.G., Welker, D., James, R.R. 2021. Presence of pathogen-killed larvae influence nesting behavior of the alfalfa leafcutting bee, (Hymenoptera:Megachilidae). Journal of Economic Entomology. 114(3):1047-1053. https://doi.org/10.1093/jee/toab030.
Cane, J.H. 2020. A brief review of monolecty in bees and benefits of a broadened definition. Apidologie. https://doi.org/10.1007/s13592-020-00785-y.
Rothman, J.A., Cox-Foster, D.L., Andrikopoulos, C., McFrederick, Q.S. 2020. Diet breadth affects bacterial identity but not diversity in the pollen provisions of closely related polylectic and oligolectic bees. Insects. 11(9). Article 645. https://doi.org/10.3390/insects11090645.
McCabe, L.M., Chesshire, P.R., Smith, D.R., Wolf, A., Gibbs, J., Griswold, T.L., Wright, K., Cobb, N.S. 2020. Bee species checklist of the San Francisco Peaks, Arizona. Biodiversity Data Journal. 8: Article e49285. https://doi.org/10.3897/BDJ.8.e49285.
Stemkovski, M., Pearse, W.D., Griffin, S.R., Pardee, G.L., Gibbs, J., Griswold, T.L., Neff, J., Oram, R., Rightmyer, M.G., Sheffield, C., Wright, K., Inouye, B.D., Irwin, R.E. 2020. Bee phenology is predicted by climatic variation and functional traits. Ecology Letters. 23(11):1589-1598. https://doi.org/10.1111/ele.13583.
Hatfield, R., Strange, J.P., Koch, J., Jepsen, S., Stapleton, I. 2021. Neonicotinoid pesticides cause mass fatalities of native bumble bees: A case study from Wilsonville, Oregon, USA. Environmental Entomology. https://doi.org/10.1093/ee/nvab059.
Schmolke, A., Galic, N., Feken, M., Thompson, H., Sgolastra, F., Pitts Singer, T., Elston, C., Pamminger, T., Hinarejos, S. 2021. Assessment of the vulnerability to pesticide exposures across bee species. Environmental Toxicology and Chemistry. 40(9):2640-2651. https://doi.org/10.1002/etc.5150.
Tabor, J.A., Koch, J. 2021. Ensemble models predict invasive bee habitat suitability will expand under future climate scenarios in Hawai‘i. Insects. 12(5). Article 443. https://doi.org/10.3390/insects12050443.
Longino, J.T., Branstetter, M.G. 2021. Integrating UCE phylogenomics with traditional taxonomy reveals a trove of new world syscia species (Formicidae: Dorylinae). Insect Systematics and Diversity. 5(2). Article ixab001. https://doi.org/10.1093/isd/ixab001.