DOI: https://doi.org/10.55406/ABRC.23
The American Association of Professional Apiculturists (AAPA) hosted its annual meeting, the American Bee Research Conference (ABRC), in Jacksonville, Florida on January 5th and 6th, 2023 in conjunction with the American Beekeeping Federation’s annual convention. This conference provides a unique opportunity for AAPA members to interact and exchange ideas between industry, academia and the beekeeping community. As an organization, AAPA consists of senior and junior scientists, students, beekeepers and inspectors who work with or study honey bees. At this year’s ABRC, we showcased nearly 50 talks and poster presentations from bee researchers from the U.S. and Canada. Research topics included Pests, Pathogens and Beneficial Microbes; Breeding, Genetics and Evolution; Chemical Ecology, Behavior and Nutrition; Pesticides and Acaricides; and Beekeeping Management, Education and Outreach. The large number of presentations given by students and postdocs was noteworthy; the high quality of the research they presented is an asset for the AAPA. We were also thrilled to host two keynote speakers: Dr. Chelsea Cook (Marquette University) and Dr. David Tarpy (North Carolina State University). AAPA is pleased to share the abstracts of this year’s meeting with the readership of Bee Culture. We hope this information helps the beekeeping community learn about the latest research developments regarding honey bees in the U.S. and beyond. Thanks for reading and for participating in this year’s ABRC.
Sincerely,
The editors of the 2023 ABRC Proceedings:
Margarita López-Uribe
Priyadarshini Chakrabarti Basu
Brock Harpur
Juliana Rangel
Michael Goblirsch
Robyn Underwood
Keynotes
Stay Cool: The social and ecological components of collective thermoregulation in honey bees
Cook, CN1
1Marquette University, Milwaukee, WI
Social animals may be particularly resilient to a changing environment because of their ability to utilize social and ecological information to behave collectively. As these social groups behave, they manipulate their environments, creating an extended phenotype. Although many studies show social animals integrate ecological and social information as their environmental context shifts, the mechanisms by which they do this are mostly unknown. Honey bees strictly regulate the temperature of their colony. When it is hot, honey bees circulate cool air into the colony by fanning. Fanning is performed by a relatively small task group (three to 50 bees) but is critical for the survival of the colony, as overheated larvae can die. This makes them an excellent model system by which to understand if and how social animals can be resilient to climate change. As such, the Cook Lab explores the sensory collection, communication and integration of the collective management of temperature in the honey bee colony. We utilize behavioral, physiological and ecological techniques to study the necessary and sufficient mechanisms of honey bee fanning. By understanding how honey bees manage their environment, we then create tools, such as cold storage, to enhance their health and survival.
A love for honey bees: a model system in applied ecology
Tarpy, DR1
1Department of Applied Ecology, North Carolina State University, Raleigh, NC
Discipline-focused research in the biological sciences focuses on a single fundamental question within a given paradigm (e.g., ecology, evolution, genetics or environmental science). A system-based approach, however, takes a different perspective by asking numerous questions and applying different techniques to a single study system, which promotes interdisciplinarity (i.e., ecology, evolution, genetics and environmental science). Here, I argue that a system-based approach using honey bees is an excellent paradigm for any number of social, organismal and sub-organismal disciplines in biological research. I review some of the work that our collaborators and lab members have conducted on the reproductive plasticity of queens, as well as how such fundamental research can be applicable to the apiculture industry to address practical issues with queen loss and diminished longevity. One general conclusion from our empirical work is that premature supersedure is more likely a function of the colony environment rather than the phenotype of the queen, and I introduce a conceptual model of how colony collective decision-making is necessary to understand the myriad of queen problems facing the industry. I conclude that only by taking a system-based approach will we be able to better understand the complexities of this model social insect and primary managed pollinator.
Pest, Pathogens and Beneficial Microbes
Evaluating the seasonal efficacy of commonly used chemical treatments on Varroa destructor population growth in honey bee colonies
Jack, C1; Boncristiani, H1,2; Prouty, C1; Ellis, J1
1University of Florida, Entomology and Nematology Department, Gainesville, FL; 2Inside The Hive Media & Consulting Inc., Odenton, MD
Most beekeepers control Varroa destructor by treating honey bee colonies with synthetic miticides. The aim of our research was to determine how commonly used chemical treatments influence Varroa population growth rates seasonally so that specific recommendations on product efficacy can be made. We applied the same eight chemical treatments following labeled rates to seasonal cohorts of honey bee colonies to determine how much the mite population growth rates were influenced by the treatments. The chemical treatments tested were: Apivar®, Apistan®, Apiguard®, MAQS®, Checkmite+®, Oxalic Acid (dribble), Oxalic Acid (shop towels) and amitraz (shop towels soaked in Bovitraz®). Many treatments were more effective at reducing Varroa populations for at least two months during Winter and Spring than in Summer and Fall. Unfortunately, most treatments were ineffective at controlling Varroa in the Summer and Fall. Of the two amitraz-based treatments, the off-label Bovitraz® treatment was more effective, being the only treatment to reduce Varroa populations successfully in all seasons. Conversely, the commonly used treatment Apivar® was only effective in the Winter. The seasonal treatment efficacy data gathered through this study will allow for the refinement of treatment recommendations for Varroa, especially regarding seasonal efficacy of each miticide and the temporal efficacy post-treatment.
Temperature affects assessment of amitraz resistance in Varroa destructor
Rinkevich, F1
1USDA-ARS Honey Bee Breeding, Genetics, and Physiology Laboratory, Baton Rouge, LA
Amitraz resistance in Varroa destructor is a phenomenon that reduces the efficacy of amitraz to control Varroa. Surveys have shown an increasing trend of amitraz resistance in many beekeeping operations. Amitraz resistance in Varroa is measured using the Apivar efficacy test, which is a consistent predictor of treatment success or failure at the colony level. To ensure the reliability of the test, we investigated how temperature affects the outcomes and interpretation of the Apivar efficacy test. The Apivar efficacy was run at a range of temperatures from 10-35°C in cages with Apivar and control cages. At temperatures higher than 30°C, the proportion of Varroa that fell off the bees under control conditions increased with temperature. In cages with Apivar, the Apivar efficacy was reduced and much more variable with lower temperatures. This result was followed with Varroa bioassays with technical amitraz at the same temperature ranges. Amitraz became less toxic at lower temperatures, thus corroborating the reduced Apivar efficacy at lower temperatures. These results show that the Apivar efficacy test should be performed between 20-30°C in order to provide consistent results. Considerations on past and future amitraz resistance monitoring efforts are discussed.
Viability of ozone fumigation as a method of sterilizing combs in commercial beekeeping operations
Reed, R1; Hopkins, BK1
1Department of Entomology, Washington State University, Pullman, WA
Beekeepers face many challenges when trying to preserve combs in good condition from year to year. Greater wax moths (Galleria mellonella), brood diseases such as American foulbrood (Paenibacillus larvae) and pesticide residues can all decrease the useful lifespan of comb. Past and current sterilization/fumigation methods are limiting and hamper adoption, but ozone fumigation presents a potential new strategy. Previous studies have shown the promise of fumigation with high concentrations of ozone as a method of overcoming wax moths, brood diseases and Nosema (Nosema ceranae) but were all conducted on a small scale. Here we summarize those findings and propose a study to implement this practice on a commercial scale. This study will monitor greater wax moth mortality, American foulbrood spore viability and pesticide residue degradation in combs placed in a cargo container with an ozone generator.
Stable isotopes elucidate Vairimorpha ceranae infection and seasonality
Webster, T1; Kamminga, K1; Gehefer, K1
1Kentucky State University, College of Agriculture, Community and the Sciences, Frankfort, KY
Stable isotopes (SI) of carbon and nitrogen are often measured in ecosystem studies to elucidate trophic steps between and within organisms. In these steps, the heavier isotopes 13C and 15N “partition” relative to the lighter isotopes 12C and 14N because they move slower through physiological processes. Except for their use in detecting honey adulteration, SI have rarely been used in honey bee research. In our study, we artificially inoculated worker bees with the Microsporidian pathogen Vairimorpha ceranae (formerly Nosema ceranae) and found that the partitioning of C and N isotopes within the bee midgut was not related to the progress of the infection. No significant difference was found in bee midguts as the infection progressed when comparing the ratio of 13C relative to 12C and 14N to 15N for control (not inoculated) and treated (inoculated) bees at zero, six, nine and 12 days post-inoculation. However, we found a significant difference in the partitioning of 13C and 15N between bees collected in September and October. A significantly higher ratio of 15N was recorded in bees collected in September than those from October. Conversely, a significantly lower enrichment of 13C was recorded in bees collected in September compared to those in October.
Interactive effects of diet quality, pesticide exposure and virus infection in honey bees
Hsieh, EM1; Dolezal, AG1
1Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL
Honey bees maintained in agricultural landscapes frequently experience the adverse effects of sublethal pesticide exposure, virus infection and poor forage, but the interactions between these factors remain complex and highly variable. To better understand these stressor dynamics, we performed a series of high-throughput bioassays measuring the survivorship of adult honey bee workers when exposed to different combinations of diet types, pesticides (chlorpyrifos, thiamethoxam and lambda-cyhalothrin) and virus (Israeli acute paralysis virus) infection. Our results showed that diet type can significantly influence survivorship response but is dependent on pesticide identity and presence of virus. Pollen consumption can improve survival when bees are exposed to viruses and field-relevant pesticide doses and can even be involved with inducing hormetic responses to chlorpyrifos ingestion, but these effects are not universal across all pesticide types. Quantification of immune gene expression reveals a complicated interaction network that suggests that pollen consumption boosts certain detoxification genes while pesticide exposure depresses it. Taken together, these findings all contribute towards an improved understanding of basic bee biology and can eventually be translated to informing bee health management decisions.
Screening for viral loads in honey bee colonies with various levels of resistance to Varroa
Levin-Nikulin, S1; Schroeder, DC2; Spivak, M1
1Department of Entomology, 1980 Folwell Ave, University of Minnesota, St Paul, MN; 2Department of Veterinary Population Medicine, University of Minnesota, St Paul, MN
Honey bee viruses, such as Deformed wing virus (DWV), Acute paralysis virus (ABPV), Kashmir bee virus (KBV) and Israeli acute paralysis virus (IAPV) are major contributors to poor colony health and survivorship. A rapid, simple, semi-automated, high throughput and cost effective method of screening colonies for viruses would benefit bee research and the beekeeping industry. Here we describe a novel approach that combines an RNA grade liquid homogenizer followed by magnetic bead capture for total virus nucleic acid extraction. We used this method to screen for viruses in colonies selected for resistance to Varroa at the University of Minnesota. We compared the results to virus loads in colonies from a migratory beekeeping operation that also selects colonies for Varroa resistance, and to unselected colonies from a commercial queen producer. Our findings showed lower viral loads in the colonies selected for resistance to Varroa and more colonies had virus loads below the limit of detection compared to unselected colonies, indicating our method of screening for viruses is effective and may be useful to screen a large number of colonies quickly and inexpensively.
Anthranilic diamides as small hive beetle control and prevention
Bartlett, LJ1,2
1Department of Entomology, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA; 2Center for the Ecology of Infectious Diseases, Odum School of Ecology, University of Georgia, Athens, GA
Small hive beetles remain a persistent problem in parts of the Southeast, where warm wet soils allow for rapid population growth and the overwhelming of colonies during the Summer dearth. Further, SHB infestation prevents beekeepers from easily provisioning colonies with additional pollen or protein feed (patties). We have demonstrated that the differential specificity of anthranilic diamide insecticides between bees and beetles allows for the control and prevention of small hive beetle infestation in the Southeast even when feeding with large patties, opening new avenues for improving bee health including during Spring splits and throughout the Summer.
Analysis of host-virus interactions in honey bees infected by Israeli Acute Paralysis Virus
Amiri, E1,2; Flores-Rodriguez, M2; Vyas, S2; Brannon, A2; Tarpy, DR3; Strand, MK4; Rueppell, O2,5
1Delta Research and Extension Center, Mississippi State University, Stoneville, MS; 2Department of Biology, University of North Carolina at Greensboro, Greensboro, NC; 3Department of Applied Ecology, North Carolina State University, Raleigh, NC; 4Life Sciences Branch, U.S. Army Research Office, DEVCOM-ARL, Research Triangle Park, NC; 5Department of Biological Sciences, University of Alberta, Edmonton, Canada
Viruses play a significant role in the current honey bee health crises. Thus, understanding the interactions between the virus and their host is critical for devising strategies to prevent or treat viral diseases. We used a micro-injection method to inject Israeli Acute Paralysis Virus (IAPV) to understand in detail the disease progression, and to define the temporal replication dynamics of IAPV in different body parts of worker honey bees at different developmental stages. In order to explore the induced systemic antiviral responses to IAPV, we quantified the expression of nine immune genes from different innate immune pathways. Our findings confirmed that two-week-old worker bees tolerate virus infection better and survive longer than their two-day-old sisters, even though the progression of viral infection is following the same pattern. Contrary to our expectations, the expression of some immune genes significantly varied among body parts and developmental stages. The findings will be discussed in detail in the context of virus-host interactions.
Is there a trade-off? Impacts of antibiotic treatments on gut microbiota and immune gene expression in honey bees (Apis mellifera)
Tomasko, N1; Hinshaw, C1; López-Uribe, MM1
1Department of Entomology, Penn State University, University Park, PA
Antibiotics serve as fundamental treatments to bacterial infections in all organisms. However, these treatments can also kill beneficial microbes that have key functions such as eliminating pathogens and maintaining immune homeostasis. Considering the links between beneficial microbes and immunity, it is critical to understand whether changes in the microbiome can reduce the individual’s ability to fight infections. Here, we use honey bees to study the immunological effects of antibiotics. Honey bees are often treated with antibiotics when infected with bacterial infections such as American foulbrood (Paenibacillus larvae). To quantify consequences of antibiotic treatment for immune function, we fed honey bees oxytetracycline followed by an immune challenge of heat-killed Escherichia coli to characterize changes in key gut bacteria and characterized immunosuppression effects. Honey bees were collected from five colonies and treated under controlled conditions over seven days. The relative expression of three immune genes and several groups of bacteria were quantified through qPCR to assess the immune gene expression and gut microbiota abundance. We did not find significant differences in survival between treatments. The combination of antibiotics and heat-killed E. coli are predicted to present trade-offs that reduce immune gene expression and microbiota abundance.
Nosema ceranae infection significantly reduces honey bee worker flight ability
Liu, F1; Zhang Y2; Huang, ZY3
1Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, China; 2Yunnan Academy of Biodiversity, Southwest Forestry University, Kunming, Yunnan, China; 3Department of Entomology, Michigan State University, East Lansing, MI
Nosema ceranae (recently renamed Vairimorpha) is an intracellular pathogen for honey bee midgut epithelial cells. Negative effects of Nosema ceranae on honey bee behavior and physiology are well studied but it is not clear whether flight ability of workers are impacted when bees are infected by this pathogen. We studied how N. ceranae infection could affect worker flight ability by using flight mills in a laboratory setting. We inoculated worker bees at day one (newly emerged bees) with nosema spores and then measured their flight ability on day 11-13 (average of 12 days). We found that Nosema ceranae infection significantly reduced the flowing parameters: flight time, flight distance, flight speed, duration of the longest flight episode and distance of the longest flight episode. Not impacted parameters included average flight speed, number of stops and duration of rests. These data suggest honey bee worker flight ability are significantly negatively impacted and this could have implications for reduced foraging in infected foragers.
eDNA as a biological tool to monitor western honey bee (Apis mellifera) microbial and arthropod communities
Marcelino, J1*; Boardman, L2*; Valentin, RE3; Boncristiani, H4; Standley, JM1; Ellis, JD1
1Honey Bee Research and Extension Laboratory, Entomology and Nematology Department, University of Florida, Gainesville, FL; 2Department of Biological Sciences & Center for Biodiversity Research, University of Memphis, Memphis, TN 38152; 3Elysium Health Inc., New York, NY, 10013; 4Inside The Hive Media & Consulting Inc., Odenton, MD, 21113; *Boardman and Marcelino should be considered joint first authors
Expedient methods to determine the identity of organisms that honey bees (Apis mellifera) contact are needed for timely detection of pests and pathogens. We explored the feasibility of using eDNA metabarcoding to profile the biota (arthropods, bacteria, fungi) associated with honey bees in order to detect pests and pathogens honey bees encounter in their environment. We sampled representative surfaces (n=13) within and outside hives of an apiary, and surrounding areas, to determine the most informative locations to detect microbial and arthropod communities. Our method proved to be reliable. We were able to detect DNA from the small hive beetle (Aethina tumida), Varroa destructor, Melissococcus plutonius (causative agent of European foulbrood), greater wax moth (Galleria mellonella) and lesser wax moth (Achroia grisella). Our protocol demonstrated that eDNA metabarcoding can accurately detect DNA from arthropods and microorganisms honey bees contact. This method can be used as a molecular predictor tool for colony health surveys.
Innate immune system components reduce infection intensity and prevalence of the fungal parasite Nosema in the honey bee Apis mellifera
Webb, J1; Zhou, J2; Baer, B1
1Department of Entomology, Center for Integrative Bee Research, University of California, Riverside, Riverside, CA, United States; 2Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, P.R.C. China
Honey bee societies consist of thousands of individuals that live in close proximity to each other within their colonies. These conditions are favorable for pathogens and parasites to establish and spread among closely related hosts. The fungal pathogen Nosema ceranae is an obligate intracellular parasite of European honey bees Apis mellifera. Infected individuals display a range of symptoms including dysentery, decreased foraging, disorientation, lethargy and infection can increase mortality and decrease the life expectancy of entire colonies. Honey bee drones are susceptible to Nosema infections as well, and the parasite is able to contaminate semen and get transferred sexually to the queen during the mating process. However, the seminal fluid of honey bees contains a range of antimicrobial molecules that are efficient in reducing Nosema spore viability. Here we used a metabolomics approach and identified several metabolites that are known to have anti fungal abilities. The metabolites specified were then used to orally treat bees artificially infected with N. ceranae. We found that bees treated with these metabolites showed significantly lower infection intensities than untreated bees. We also show that the prevalence of infection was reduced by ~40% in bees that received these treatments.
Comparative quantification of honey bee (Apis mellifera) associated viruses in wild and managed colonies
Dickey, M1 and Rangel, J1
1Texas A&M University, Department of Entomology, College Station, TX
The most detrimental threat to honey bee (Apis mellifera) health continues to be the ectoparasitic mite, Varroa destructor, which has been linked to colony losses worldwide. Varroa is also a prolific vector of several honey bee-associated viruses. Wild honey bee colonies are more tolerant to Varroa parasitization than managed colonies. Because they live in feral conditions, wild colonies are not treated for Varroa control, allowing for the natural selection of mite tolerant bees. To date, there is limited information about virus prevalence in wild honey bee populations. The Welder Wildlife Refuge (WWR) is a unique site to study the viral landscape of wild bees in the Southern U.S. Our goal was to identify and quantify honey bee-associated viruses in a wild population and compare the presence of these viruses to that in the nearest managed apiaries. We found significant changes of viral titers over time at the WWR for two major viruses (DWV and BQCV). However, there was not a significant difference in viral titers between the managed population and WWR. Our results indicate that perhaps wild honey bees are more tolerant to virus infections than managed colonies in spite of them being equally prone to virus infections, given that wild colonies exhibit lower yearly losses than managed operations.
Screening new compounds against small hive beetles (Aethina tumida) with a novel acute toxicity bioassay and field trial
Kleckner, K1; De Carolis, A1; Jack, C1; Stuhl, C2; Formato, G3; Ellis, JD1
1Honey Bee Research and Extension Laboratory, Entomology and Nematology Department, University of Florida, Gainesville, FL; 2Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville, FL; 3Apicoltura, Produzioni e Patologia Delle Api, Istituto Zooprofilattico Sperimentale Delle Regioni Lazio e Toscana, Rome, Italy
Beekeepers need new registered products to control small hive beetles (SHBs), Aethina tumida, a significant pest of western honey bee (Apis mellifera) colonies. Few approved chemical control options exist and those available are often not effective. We developed a novel acute laboratory bioassay and field trial that delivers compounds of interest to adult SHBs via pollen. We assessed the efficacy of coumaphos (only approved in-hive treatment in the U.S.), acetamiprid (frequently used beetle control) and fipronil (commonly used in urban pest baits and by beekeepers to control SHBs) as SHB control agents. Adopting our bioassay, we found acetamiprid (LC50 = 20.5 µg/g) to be more toxic to SHBs than was coumaphos (LC50 = 1250 µg/g), yet less toxic to SHBs than was fipronil (LC50 = 1.78 µg/g). In our field trial, colonies treated with acetamiprid and fipronil had significantly reduced (p < 0.001) SHB populations over those of control colonies. Traps containing acetamiprid retained significantly higher (p < 0.001) numbers of dead SHBs than did traps containing fipronil. We consider acetamiprid to be a promising control agent against SHBs. Future research is needed to assess the effects of acetamiprid on colony health, hive products and surrounding environments.
Breeding, Genetics and Evolution
Hangry bees: Pollen deprivation affects temper in Pol-line honey bees (Apis mellifera)
Walsh, EM1; Simone-Finstrom, M1; Avalos, A1; Ihle, K; Lau, P2
1USDA-ARS Honey Bee Breeding, Genetics, and Physiology Research Unit, 1157 Ben Hur Rd., Baton Rouge, LA; 2USDA-ARS
Pollinator Health in Southern Crop Ecosystem Research Unit, 141 Experiment Station Rd., P.O. Box 346, Stoneville, MS
Temperament of honey bees (Apis mellifera) has long been associated with genetic background, with some honey bee populations (e.g. Africanized bees) being associated with “hot” temperaments. However, beekeepers have also traditionally associated environmental conditions with temperament, as bees that are queenless or in a dearth are commonly more aggressive than they were before entering these conditions. In this study, we simulated a pollen dearth by utilizing pollen traps on colonies, half of which collected pollen and half of which were kept closed. We performed aggression assays and found that colonies deprived of pollen were more aggressive (or “hangry”) than their non-pollen deprived counterparts in the same beeyard. Foragers were collected from these colonies on a weekly basis throughout the five week experiment and the expression of 4+ genes associated with temperament were examined. We have found that, regardless of genetic background, an environmental stimulus can play a pivotal role in honey bee temperament. This is something both breeders and scientists should keep in mind as they make operational and research decisions in the future.
Optimization of honey bee queen production practices for greater productivity and performance in northern climates.
Nasr, M1; Wilson, G2
1Saskatchewan Beekeepers Development Commission- Tech Adaptation Program, #141 – 800 Central Avenue, Prince Albert, SK, S6V 6G1, Canada; 2Saskatchewan Ministry of Agriculture, #141 – 800 Central Avenue, Prince Albert, SK, S6V 6G1, Canada
Recent surveys of Winter losses in Canada showed one of the top three causes of high colony mortality is poor queen quality. To address this problem, many Canadian beekeepers rely on importing queens for making new colonies. Although this is a common practice; Saskatchewan beekeepers have been active in raising their own queens. Investigating the quality of produced queens showed that queen production can start as early as mid-May, but queens produced mid-June to early August had significantly higher average number of sperm per queen (6.27±1.08mil). Produced queens significantly varied in head and thoracic measurements among producers and within the rearing season. The average number of sperm per locally produced queen was 2.96±1.54mil and this was overall 1.6 times higher than queens imported from other provinces in Canada or the USA in 2021. Specific recommendations were tailored and given to each local participant beekeeper based on the results in our assessments. Following-up with those queen producers in 2022, significant improvement in the average number of sperm (3.87±1.42mil) and reduced variation among tested queens were found. In 2022, testing imported queens showed that 40% had less than one million sperm per queen. These findings showed that efforts to produce quality queens in northern climates is viable and locally produced queens can be better in improving colony survivorship.
Reproductive mechanisms of evolutionary differentiation of the honey bee (Apis mellifera L.)
Ritchie, K1; Sheppard, WS
1Washington State University, Pullman, WA
Honey bee (Apis mellifera) queens store and use sperm from mating with multiple drones early in life. Queens can mate with drones from multiple subspecies to produce viable offspring. There is evidence to suggest that queens differentially use sperm during fertilization, but it is unclear when and where sperm selection is taking place in the queen reproductive tract. To evaluate differential sperm storage and use in honey bee queens, queens from different U.S. strains representing Old World subspecies were instrumentally inseminated with semen from one or multiple strains. Queens inseminated with semen from one strain were sacrificed and dissected 40 hours after insemination. Sperm counts from the dissected spermatheca were performed and data suggests that queens preferentially store more sperm when they are inseminated with semen from drones of the same strain. Queens inseminated with semen from multiple strains were introduced to colonies to evaluate sperm use over time. Using multiplex PCR, microsatellite analysis will be performed to determine paternity among honey bee worker progeny in the population. Findings from this research will further our understanding of female-male interactions in the honey bee queen reproductive tract and their effects on sperm storage and use.
A dose-response transcriptome of honey bee workers: characterizing gene expression across a large range of oxidative stress
Herman, JJ1; Carswell, B1; Hofmeyer, J1; Rueppell, O1
1Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
Stress response in insects is often studied through single behaviors, traits or genes to identify quantitative impacts of sublethal stress dosages. While this approach has been used to study stressors and beneficial treatments in honey bees, experimental designs rarely combine a range of doses with a large number of biological outcomes due to costs and/or feasibility. Using a cost-efficient Tag-seq approach, we create a dose response of the entire honey bee transcriptome to the oxidative stressor Paraquat, a herbicide that induces oxidative stress in a wide variety of organisms. Across 10 doses, we vary the stress X-fold and evaluate the physiological responses in 96 whole transcriptome profiles. This whole transcriptome strategy along with a large dose range allows us to obtain both a gene and process view of how honey bees, and potentially other insects, respond to dramatically varying levels of oxidative stress. We are able to identify key biological processes that underlie resistance to oxidative stress and also how the transcriptome appears in response to doses that result in certain death. This study paradigm could help as a general framework for testing other stressors or beneficial treatments both alone and in conjunction to understand stressor-stressor and stressor-treatment interactions and hopefully contribute to improving honey bee health in the future.
Upgrade to the Russian honey bee genotype identification assay
Avalos, A1; Bilodeau, L1
1USDA-ARS Honey Bee Breeding, Genetics, and Physiology Research Unit, 1157 Ben Hur Rd., Baton Rouge, LA
Russian honey bees (RHB) are a Varroa-resistant breeding population developed by USDA-ARS that first incorporated genetic stock identification (GSI) as part of the selection strategy. Novel sequencing approaches and high throughput microfluidic chemistry has afforded an excellent opportunity to update the existing assay. Here we outline a methodological framework that capitalizes on both historical and novel genetic variation to arrive at an updated assay with increased accuracy and processing power. This approach provides an inherently modular framework that can be readily incorporated as a genetic survey of breeding populations or alternatively, modified to examine genetic variation associated with specific traits when available. Ultimately this work provides another genetic-based tool towards the ultimate goal of breeding for healthier more productive bees.
Beekeeping Management, Education and Outreach
Rough hives stimulate propolis production in support of bee health
Simone-Finstrom, M1; Shanahan, M2; Read, Q3; Spivak, M2
1USDA-ARS Honey Bee Breeding, Genetics, and Physiology Research Unit, 1157 Ben Hur Rd., Baton Rouge, LA; 2Department of Entomology, University of Minnesota, 1980 Folwell Avenue, St Paul, MN; 3USDA-ARS, SEA, 840 Oval Dr. 2126 Plant Sciences Building, North Carolina State University, Raleigh, NC
When wild honey bee (Apis mellifera) colonies nest in hollow tree cavities, they coat rough cavity walls with a thin layer of propolis, derived primarily of plant resins. The resulting “propolis envelope” serves structural and therapeutic functions inside the hive. In this study, we monitored colonies in hive types with different surface texture treatments (rough wood boxes, boxes with propolis traps and standard, smooth boxes) to determine if these surfaces encourage managed colonies to deposit more propolis. We examined the effect of propolis on colony health, pathogen loads, immune gene expression, bacterial gene expression and honey production in stationary and migratory beekeeping contexts. Migratory rough box colonies were significantly larger than migratory control colonies by the end of year one. In both stationary and migratory operations, propolis deposition was correlated to a seasonal decrease and/or stabilization in expression of multiple immune and bacterial genes, suggesting that propolis-rich environments contribute to hive homeostasis. There was also a significant decrease in Melissococcus plutonius gene expression with non-significant decreases in clinical symptoms of European foulbrood and Varroa loads. These findings provide support for implementation of rough box hives as a means to support propolis collection and colony health in multiple beekeeping contexts.
Perceived impacts of unusual and extreme weather events on beekeeping
Steinhauer, N1,2; Aurell, D3; Bruckner, S3; Wilson, M1,2; Williams, G3
1Department of Entomology, University of Maryland, College Park, MD; 2Bee Informed Partnership, College Park, MD; 3Department of Entomology and Plant Pathology, Auburn University, Auburn, AL
Unusual and extreme weather events, such as heat waves, droughts, wildfires, heavy rainfall and storms, can have serious impacts on honey bee (Apis mellifera) colonies: droughts can limit plants’ nectar and pollen production; rain and wind can limit foraging time; wildfires and floods can destroy colonies outright or their surrounding resources. With extreme events becoming more frequent, we attempted to quantify their impact on U.S. beekeepers through a perception questionnaire included in the 2022 Bee Informed Partnership survey. Droughts were seen as the most impactful event type on colonies; 25% of U.S. beekeepers (representing 87% of colonies) reported negative impacts from droughts in 2021-2022. The majority of reports came from the West region and migratory beekeepers, and commercial beekeepers were more likely to report droughts. By contrast, “high winds and storms” were widely reported by beekeepers (37%, representing 23% of colonies), but mostly without noticeable impact. Overall, the vast majority of impacts from unusual weather events were negative. This was the first attempt to document the prevalence and severity of weather impacts on the U.S. honey bee population and beekeeping. A better understanding of the scope of their potential impact should help stakeholders and policymakers better plan for changing conditions.
A longitudinal experiment shows that organic honey bee colony management supports healthy and productive colonies
Underwood, RM1; Lawrence, B1; Turley, NE1; Kietzman, P2; Cambron-Kopko, L1; Traver, BE3; López-Uribe, MM1
1Department of Entomology, Penn State University, University Park, PA; 2School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA; 3Department of Biology, Penn State Schuylkill, Schuylkill Haven, PA
Honey bee, Apis mellifera, colonies face numerous challenges, but management practices can help mitigate some of the negative effects of these stressors, but these practices vary significantly, resulting in striking differences in the type and frequency of chemicals used for pest and parasite control. The goal of this longitudinal, three year study was to use a systems approach to experimentally test the role of three representative beekeeping management systems (conventional, organic, chemical-free) on the health and productivity of stationary honey-producing colonies. We found that, over three Winters, the rates of survival for colonies in the conventional and organic management systems were at least two times higher than under chemical-free management. Varroa mite levels in the Fall were 4.52 and 3.53 times higher in the chemical-free than in the conventional and organic management systems, respectively. This led to higher levels of deformed wing virus (DWV) and expression of immune genes. Here, we experimentally demonstrated that beekeeping management practices are key drivers of the survival and productivity of managed honey bee colonies. More importantly, we found that the organic management system supports healthy and productive colonies, and can be incorporated by beekeepers as a sustainable approach for stationary beekeeping operations.
Market implications of changes in climate, land coverage and annual colony loss rates for U.S. commercial beekeeping operations
Rangel, J1; Fei, C2; Chen, Y2; Woodward, R2
1Department of Entomology, Texas A&M University, College Station, TX; 2Department of Agricultural Economics, Texas A&M University, College Station, TX
In this project, we improved the current econometric models of the U.S. pollination market and updated the integrated model based on our previous published version. By expanding the research area to cover bee movement, pollination behavior and honey production in the lower 48 U.S. states, the data that encompass annual colony losses and splitting colonies by two units are parameters that were upgraded in the new model. Then, the impact of Summer and Winter percentage loss of colonies on the honey bee pollination and honey production market using the new developed model were investigated. We also embedded our data into the integrated econometric models of the climate change impact on honey production rates and honey bee loss rates, calculated using USDA data on the state-level “dead outs” divided by the maximum inventory of colonies in each state during a given period. The integral impact of climate change on the honey bee pollination market was analyzed using the new U.S. bee movement model. Our model and results will help to identify the climate impact on the honey production rate, honey loss rate and the honey bee pollination market in the U.S. Moreover, the climate change impact and the market changes under different policy and pollination scenarios are projected.
Seeing is bee-lieving – what happens after a sugar shake assay?
Tsuruda, JM1; Bruckner, S2; Underwood, R3; Williams, G2
1Department of Entomology & Plant Pathology, University of Tennessee, Knoxville, TN; 2Department of Entomology & Plant Pathology, Auburn University, Auburn, AL; 3Department of Entomology, Penn State University, University Park, PA
Varroa destructor remains one of the most impactful and widespread challenges in modern beekeeping. Beekeepers are encouraged to monitor to determine when populations have surpassed the economic threshold for intervention. While similar in the method of collection of bees, the alcohol wash destructively monitors for mites while the sugar shake is considered non-destructive and is often referred to as “safe” for the bees, leading many beekeepers to favor this assay despite research showing its lower mite recovery. To investigate whether the sugar shake assay affects assayed bees, we compared bees that underwent the sugar shake assay versus bees in a powdered sugar-coated group (no shaking), and a control group (no powdered sugar or shaking), by documenting their recovery in the hive five days later. Lower recovery rates were found for shaken bees and varying behavioral responses to the focal bees were observed, providing possible explanations for the recovery rates. While sugar shake assays are better than not monitoring at all, our results provide considerations for beekeepers who choose the sugar shake assay believing it is safe for the bees. Understanding and showing impacts of this assay on bees may influence beekeepers’ behaviors and increase the adoption of the alcohol wash.
Examining methods for Varroa destructor control in honey bee colonies (Apis mellifera) using oxalic acid vaporization: the difference between control versus reduction
Berry, J1; Bartlett, L1,2; Braman, K1; Bruckner, S3; Baker, C3; Delaplane, K1; Williams, G3
1Department of Entomology, University of Georgia, Athens, GA; 2Center for the Ecology of Infectious Diseases, Odum School of Ecology, University of Georgia, Athens, GA; 3Department of Entomology & Plant Pathology, Auburn University, Auburn, AL
Varroa destructor remains the leading cause of honey bee mortality in the United States. Mounting evidence of resistance to synthetic miticides means beekeepers are struggling to keep their colonies alive despite a whole host of other cultural, genetic and chemical options to control this formidable pest. Oxalic acid (OA), when vaporized, has proven to be an effective treatment against the phoretic phase of V. destructor, but has its limitations since the compound cannot penetrate brood cell wax caps. We present large, multi-apiary studies examining OA application during brood-rearing periods for V. destructor control. We show that repeated applications of OA while brood is present is capable of preventing V. destructor population growth but, does not decrease mite populations. More recently, we studied whether incorporating a forced brood break while vaporizing with OA would be a more effective treatment in controlling V. destructor. This option is designed to work with the ‘beekeeping calendar’ based on re-queening schedules or during a brood dearth. We show that a short brood break, achieved by confining the queen in a honey super above an excluder, increases the effectiveness of OA vaporization five-fold, and effectively reduces V. destructor populations.
Pesticides and Acaricides
How frequent is synergy to honey bees among pesticide combinations typically used in agricultural operations?
Taenzler, V; Weyers, A1; Maus, C1; Ebeling, M1; Levine, S2; Cabrera, A2; Schmehl, D2; Gao, Z1; Rodea-Palomares, I2
1Bayer AG, Crop Science, Alfred-Nobel-Strasse 50, 40789 Monheim am Rhein, Germany; 2Bayer CropScience LP, 700 Chesterfield Parkway West, Chesterfield, MO
Understanding the frequency of non-additive effects (synergism and antagonism) is important in the context of pesticide risk assessment. The goal was to investigate the prevalence of non-additive effects of pesticides to honey bees. We investigated mixtures of insecticides and fungicides of different chemical modes of action and classes and whether the experimental toxicity of the mixtures could be predicted based on the Concentration Addition (CA) model for acute contact and oral adult bee toxicity tests. Further, we investigated the appropriate Mixture Deviation Ratio (MDR) thresholds that should be used for the identification of non-additive effects based on acceptable rates for false positive and true positive findings. We found that a deviation factor of MDR = 5 is a sound reference for labeling potential non-additive effects in acute adult bee experimental designs. We found that only 2.4% and 9% of the mixtures evaluated had an MDR > 5 (potential synergy) and MDR < 0.2 (potential antagonism), respectively. The frequency and magnitude of deviation from additivity found for bees in this study are consistent with those of other terrestrial and aquatic taxa. Our findings suggest that synergy of pesticide mixtures to bees is rare and is not random but have mechanistic basis.
Toxicity of the not so “inert ingredients” in pesticides to adult worker honey bees
Shannon, B1; Johnson, RM2
1Environmental Sciences Graduate Program. The Ohio State University, Wooster OH; 2Department of Entomology, The Ohio State University, Wooster, OH
The principal functioning agents (PFAs) that make up spray adjuvants and serve as “inert ingredients” in formulated pesticides are a diverse group of agrochemicals that are added to pesticides with the intention of improving the function of spray application through enhanced leaf sticking, spreading and penetration. The significant honey bee colony losses that have been reported during and after almond pollination in California may be related to honey bee exposure to these compounds. The aim of this research was to determine if individual adjuvant PFAs applied during almond bloom can cause increased mortality in adult worker honey bees exposed to simulated spray applications from a Potter Spray Tower. This study established the acute toxicity, expressed as LC50, of sixteen adjuvant PFAs applied during almond bloom. Results show that some PFAs, especially in the ethoxylate, organic polymer and organo-silicone chemical groups, can cause adult bee mortality when applied alone at field relevant concentrations. A better understanding of the inert ingredients that are driving adjuvant and adjuvant-pesticide tank mixture toxicity to honey bees will play a key role in informing “Best Management Practices” for pesticide applicators spraying pesticides during bloom, when honey bee exposure is likely.
Toxicity of potential new varroacides to honey bee queens under laboratory and field conditions
Bahreini, R1; Nelson, L1; Hofmeyr, J1; Smith, T1; Rueppell, O1
1Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
Varroa mites are threatening honey bee colony survivorship and the sustainability of beekeeping. Evolution of resistance and low efficacy of current control efforts have increased the demand for new treatment tools that exhibit high efficacy, while minimizing adverse effects on honey bees. Based on previous investigations that assessed Varroa and worker bee mortality from 26 potential miticides (Bahreini et al.), we selected five promising candidates to test their long-term effects on honey bee mated-queens. Using a combination of lab and field experiments, we assessed queen mortality, queen performance, bee and brood viability, mite mortality, as well as sublethal effects on queen weight and sperm viability. As predicted, toxicity to queens was dose-dependent and queen survival rate was greater for 1% compared to 10% contact exposure in the laboratory bioassay. Queens proved to be less susceptible than workers in most cases. Field studies indicated that queens are able to tolerate 1000 mg active ingredient of two compounds per nucleus hive. At this concentration, the compounds showed efficacy against Varroa, while no adverse phenotypic effects on queens or adult bee populations were observed in treated colonies. Physiological sublethal effects on queens, workers and mites will be assessed in future transcriptomic studies. Further research is required to comprehensively investigate the potential of our candidate substances for effective and safe Varroa control under apicultural field conditions.
Bioacoustics monitoring to detect changes in honey bee visitation to blooming soybeans associated with an insecticide application
Johnson, R1; Forrester, K1; Lindsey, L2; Lin, CH3
1Department of Entomology, The Ohio State University, Wooster, OH; 2Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH; 3Department of Entomology, The Ohio State University, Columbus, OH
Utilization of soybean flowers by honey bees has been under-appreciated because it is difficult to observe pollinator activity on flowers through the dense soybean canopy. In the absence of obvious pollinator activity, insecticides carrying label language prohibiting application “if bees are visiting the treatment area” are often applied during soybean bloom. Bioacoustic methods provide a practical approach to (1) assess bee activity in soybeans and (2) determine the effect of an insecticide application on bee activity. An array of eight microphones were affixed to stakes and placed in four experimental soybean fields and recording was started. The day after microphone placement, half of each field, containing four microphones, was treated with the insecticide Fastac EC (alpha-cypermethrin). The following day recording was stopped and microphones were recollected. Honey bee activity in audio files was identified based on the wing beat frequency of honey bees (234±13.9 Hz) using automated analysis, followed by manual validation. Results indicate that honey bee activity in soybean fields was common and was not substantially affected by insecticide application. This work supports recommendations that insecticide applications should not be made to blooming soybeans during daytime hours when pollinators are actively visiting soybean flowers.
Chemical Ecology, Behavior and Nutrition
Monitoring the spread of defensive honey bee behavior in Pennsylvania
Dean, CAE1; Underwood, RM1; Given, K2; Harpur, BA2; López-Uribe, MM1
1Department of Entomology, Penn State University, University Park, PA; 2Department of Entomology, Purdue University, West Fayetteville, IN
Defensive behavior among managed colonies across the Americas, including the Southern United States, represents one of the phenotypic consequences of crossing honey bees of European origin and a South African subspecies. The resulting cross, referred to as African hybrid honey bees (AHBs), are defined as possessing >20% genetic material derived from African lineages and showing defensive behavior. Here, we explore whether defensive colonies in Pennsylvania, a Northern state where AHBs are not documented to have previously established, show evidence of defensive behavior suggesting possible introgression from African lineages. We first confirmed the designation of ‘defensive’ versus ‘non-defensive’ colonies, as identified by local beekeepers, using an assay wherein the number of stings was recovered from a 6 x 9 cm leather patch waved in front of the colony entrance for one minute upon agitation. Next, we sampled workers for genomic sequencing to perform an ancestry analysis assessing whether defensiveness in Pennsylvania colonies is correlated to a higher proportion of DNA derived from African lineages. Our results confirm the presence of highly defensive colonies in the state of Pennsylvania. We are currently working on developing a pipeline that will enable local beekeepers to diagnose, monitor and manage highly defensive colonies.
Pesticide stress drives premature self-removal behavior in honey bee (Apis mellifera) workers
Twombly Ellis, J1; Rangel, J1
1Texas A&M University, Department of Entomology, College Station, TX
Honey bees are challenged by multiple factors, many of which act concomitantly to affect colony health. One negative effect of these stressors is accelerated age polyethism wherein stressed bees perform tasks at a younger age than healthy bees. We recently documented an extreme example of this behavior that we termed premature self-removal. General developmental stress was shown to cause honey bees to remove themselves from the colony before they could fly, leading them to die prematurely. In this study, we tested the hypothesis that undergoing pesticide stress during pupal development can cause adult workers to perform this behavior. We used two pesticides commonly found in wax in honey bee colonies, Amitraz and Chlorothalonil. To determine if these pesticides lead to self-removal behavior, we stressed bees by rearing them in contaminated wax. We individually tagged focal bees upon emergence and introduced them into an observation hive. Tagged bees were followed and monitored for premature self-removal. Our results showed that pesticide stressed bees self-removed more than control bees. The Chlorothalonil stressed bees self-removed at a statistically significantly higher rate. We found that individual, field relevant pesticide levels cause this detrimental behavior. Therefore, contamination by multiple pesticides likely further increases self-removal rates.
Sublethal effects of gelsemine, a toxic alkaloid found in yellow jessamine nectar, on queen bee performance
Goblirsch, M1; Werle C1; Hamilton A2; Robinson GE3; Adamczyk J1
1USDA-ARS, Southern Horticultural Research Laboratory, Poplarville, MS; 2University of Illinois at Urbana-Champaign, Carl R Woese Institute for Genomic Biology, Urbana, IL; 3University of Illinois at Urbana-Champaign, Department of Entomology, Neuroscience Program, and Carl R Woese Institute for Genomic Biology, Urbana, IL
Yellow jessamine is native to the southeast U.S. The plant blooms in late Winter/early Spring, producing abundant, fragrant flowers that attract honey bees. It is a popular ornamental, but also establishes readily along roadsides and recently disturbed habitats. Yellow jessamine is a significant source of early season nectar, but there is a downside to its utilization, as beekeepers have observed weakening of colonies during its bloom. Gelsemine, a toxic alkaloid found in yellow jessamine nectar, is the likely cause of these negative effects, but few studies have explored this phytochemical beyond its acute toxicity. We used Queen Monitoring Cages (QMCs) maintained under controlled, laboratory conditions to expand understanding of how gelsemine may weaken colonies. These functional colony units contain a laying queen, 50 attendants and ad libitum provisions that included either untreated sugar solution or sugar solution containing 20 or 100 ppm gelsemine. Preliminary findings suggest that queens in QMCs given gelsemine at naturally occurring concentrations had reduced egg-laying with little to no effects on adult mortality, resource consumption or hatching success. Our results support that chronic exposure to gelsemine, as may occur during yellow jessamine bloom, could lead to a reduction in worker population and ultimately weaken the colony.
Engineered microalgae as a novel pollen substitute and therapeutic delivery system
McMenamin, A1; Weiss, M2; Meikle, W2; Martin, A1; Simone-Finstrom, M1; Ricigliano, V1
1USDA-ARS, Honey Bee Breeding, Genetics, and Physiology Research, Baton Rouge, LA; 2USDA-ARS Carl Hayden Honey Bee
Research Center, Tucson, AZ
With a rapidly growing human population and a changing climate, it is more important to devise sustainable agricultural solutions. Intensifying land-use has resulted in extirpations of native pollinators and a reduction in insect biomass, increasing our reliance on honey bees (Apis mellifera). However, beekeeping is threatened by unsustainable colony losses due to pests (e.g., Varroa destructor), pathogens (e.g., viruses) and inadequate nutrition. Here, we show that a microalgae-augmented diet improves colony size and thermoregulation when supplied to commercial colonies relative to control colonies. Microalgae-supplemented diet resulted in a unique expression profile of nine stress-response genes and biomarkers in nurse bees compared to controls. Bees fed microalgae that have been engineered express immune-stimulating biomolecules against deformed wing virus (DWV) – a major threat to colony health – survive longer and have reduced DWV genome equivalents when injected with DWV relative to various controls. Larvae reared on royal jelly supplemented with microalgae were challenged with 106 DWV genome copies at pupation and scored for deformities at eclosion. Individuals reared on engineered algae showed significantly lower rates of deformity than individuals reared on control jelly. Our data demonstrates that microalgae are a promising nutritional supplement and a scalable therapeutic delivery system for apiculturists.
Beebread production involves functional phytochemical changes in the diet of honey bees
Wu, W-Y1; Liao, L-H1; Berenbaum, MR1
1Department of Entomology, University of Illinois at Urbana-Champaign, 505 S. Goodwin Ave., Urbana, IL
Throughout its range, the western honey bee Apis mellifera can process foraged pollen via fermentation into bee bread for consumption during times of dearth. In addition to its nutritional amino acid and lipid content, pollen is rich in phytochemicals, which are now known to play a functional role in enhancing bee defenses against pesticides and pathogens. Beebread production has long been assumed to involve preservation of nutrients and little else. Beyond nutrient content, however, we examined the alteration of functional phytochemicals during beebread production by comparing the phytochemical profile of foraged pollen and beebread samples collected during the same floral blooming period. Chemical analysis via phenolic extraction revealed that the bee bread samples contained a greater diversity and abundance of phytochemicals. Three functional phytochemicals—p-coumaric acid, kaempferol and quercetin—were more abundant in the beebread than in the pollen. Moreover, in vitro cage-rearing assays showed that the longevity of adult honey bee workers was differentially affected by pollen or bee bread in the diet. Our findings suggest that beebread has potential as a supplement to enhance colony heath.
Developing a pollen nutrition database for north America: healthy food for healthy bees
Jennings, L1; Simon, M 2; Sagili, R2; Chakrabarti, P1,2
1Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS; 2Department of Horticulture, Oregon State University, Corvallis, OR
Poor nutrition is one of the major stressors of bee species and is a main contributor to loss in pollinator populations. Bees are currently faced with many nutritional challenges including loss of forage habitat and monoculture. The aim of this project is to promote better nutrition for bees by learning which floral resources are nutritionally optimal for all bees based on the nutritional composition of their pollens. This study will first use various methods of pollen collection in order to collect sufficient pollen from each target species of plants. Next, the collected pollen samples will be analyzed in the lab using basic biochemical assays, as well as mass spectrometry based methods, to determine the nutritional quality of the pollen. The pollen will be analyzed for its concentration of proteins, lipids, amino acids, sterols, metabolites and phytochemicals. Finally, all of this data collected will be compiled into an online database showcasing the nutritional quality of each plant species’ pollen. This database can be used by beekeepers, conservation groups and growers to scientifically select forage plants for pollinators.
Interactive effects of pesticides and nutrition on honey bee health
Lau, P1; Tundo, G1; Zhu, Y1; Zhang, W1
1USDA-ARS Pollinator Health in Southern Crop Ecosystem Research Unit, Stoneville, MS
Honey bees often encounter a variety of stressors in their environment, including poor nutrition and pesticides. These stressors interact and can be exacerbated in heavily anthropized habitats such as large-scale agroecosystems. In this study, we build upon our previous work on honey bee nutrition and examine how diets varying in macronutrient ratios can affect nurse bee susceptibility to pesticide stressors. We did so by orally exposing nurse bees to varying sublethal concentrations of clothianidin (CLO), a neonicotinoid insecticide known to have sublethal and lethal effects on honey bees, after newly emerged bees were given an artificial high protein diet, intermediate diet, high lipid diet, natural pollen diet or no diet. In the absence of pesticide stressors or at low concentrations, bees given the higher protein, balanced diet, and natural pollen had better survivorship compared to bees given no diet or a high lipid diet. However, bees given natural pollen had lower susceptibility when exposed to higher concentrations of CLO. Our preliminary results suggest that there may be other nutrients in pollen beyond crude protein and lipids that improve nurse bee tolerance to pesticide stress.
