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Honey bees contribute substantially to the world economy through pollination services and honey production. In the U.S. alone, honey bee pollination is estimated to contribute at least $11 billion annually, primarily through the pollination of specialty crops. However, beekeepers lose about half of their hives every season due to disease, insecticides, and other environmental factors. Here, we explore and validate a spatiotemporal statistical model ofVarroa destructormite burden (in mites/300 bees) in managed honey bee colonies, exploring the impact of both environmental factors and beekeeper behaviors. We examine risk factors forVarroainfestation using apiary inspection data collected across the state of Illinois over 2018–2019, and we test the models using inspection data from 2020–2021. After accounting for spatial and temporal trends, we find that most environmental factors (e.g., floral quality, insecticide load) are not predictive ofVarroaintensity, while lower numbers of nearby apiaries and several beekeeper behaviors (e.g., supplemental feeding and mite monitoring/treatment) are protective againstVarroa. Interestingly, while monitoringandtreating forVarroais protective, treatingwithoutmonitoring is no more effective than not treating at all. This is an important result supporting Integrated Pest Management (IPM) approaches. 

Corpse-mediated pathogen transmission is a viable route through which naïve hosts can become infected, but its likelihood for honey bee-associated viruses is largely unknown. While these viruses can be easily detected in deceased bees, it remains unclear if they stay infectious within postmortem hosts or if enough viral RNA degradation-and subsequently virus inactivation-occurs post-host death to render these viruses inviable. This knowledge gap has important implications for how researchers perform honey bee virus studies and for our general understanding of honey bee virus transmission. To better understand the resiliency of honey bee-associated viruses within deceased hosts, we first tested the hypothesis that postmortem specimens, stored in colony-normal temperature and humidity conditions, can be reliably used to quantify virus abundance. To determine this, we experimentally-infected adult honey bees with Israeli acute paralysis virus (IAPV) and then measured the virus levels of individuals sampled live or at different postmortem time points (4, 12, 24, and 48 hours post-death) using RT-qPCR and a standard curve absolute quantification method. We found no significant differences based on when bees were sampled, indicating that postmortem honey bees are statistically comparable to using live-sampled bees and can be reliably used to quantify absolute IAPV abundance. We then performed a follow-up experiment that determined whether or not the IAPV detected in postmortem bees remained infectious over time. We found that IAPV extracted from postmortem bees remained highly infectious for at least 48 hours post-death, indicating that any viral RNA degradation that may have occurred during the postmortem interval did not adversely affect IAPV's overall infectivity. The results from this study suggest that IAPV is more resilient to degradation than previously assumed, support the use of postmortem bees for downstream IAPV analyses, and indicate that postmortem hosts can act as sources of IAPV infection for susceptible individuals. 

Abstract Mobile genetic elements (MGEs), such as plasmids and bacteriophages, are major contributors to the ecology and evolution of host-associated microbes due to a continuum of symbiotic interactions and by mediating gene flow via horizontal gene transmission. However, while myriad studies have investigated relationships between MGEs and variation in fitness among microbial and eukaryotic hosts, few studies have incorporated this variation into the context of MGE evolution and ecology. Combining HiC-resolved metagenomics with the model honey bee worker gut microbiome, we show that the worker gut contains a dense, nested MGE community that exhibits a wide degree of host range variation among microbial hosts. Using measures of gene similarity and syntenty, we show that plasmids likely mediate gene flow between individual honey bee colonies, though these plasmids exhibit broad host range variation within their individual microbiomes. We further show that phage-microbe networks exhibit high variation among individual metagenomes, and that phages show broad host range with respect to both the number and phylogenetic distance of their hosts. Finally, we provide evidence that measures of nucleotide variation positively correlate with host range in bee-associated phages, and that functional targets of diversifying selection are partitioning differently between broad or narrow host range phages. Our work underscores the variability of MGE x microbial interactions within host-associated microbial communities and highlights the genomic variation associated with MGE host range diversity. 

Abstract Despite the queen’s crucial reproductive role in honey bee colonies, queen diet and feeding behavior remain remarkably enigmatic, with most studies assuming they are solely fed nutritious glandular secretions (i.e., royal jelly) by workers. This colors our understanding of basic honey bee biology and how governmental agencies assess pesticide risk. We hypothesized that adult queens also consume honey and pollen. Through experiments with queenright laboratory microcolonies fed with marked diets, we demonstrate that queens are fed pollen and nectar by workers and can also feed directly. We then measured pollen content in mature, unmanipulated queens sacrificed from 43 conventional field colonies from two distinct geographical regions. Similar to workers, we found pollen in almost all queens guts, though at expectedly lower quantities than in young workers. These findings suggest queens have a more complex, dynamic diet than previously thought, raising new questions about how dietary habits and feeding behaviors influence pesticide risk and other aspects of queen biology. 

Abstract Honey bees are important organisms for research in many fields, including physiology, behavior, and ecology. Honey bee colonies are relatively easy and affordable to procure, manage, and replace. However, some difficulties still exist in honey bee research, specifically that honey bee colonies have a distinct seasonality, especially in temperate regions. Honey bee colonies transition from a large society in which workers have a strict temporal division of labor in the summer, to a group of behaviorally flexible workers who manage the colony over winter. Furthermore, opening colonies or collecting bees when they are outside has the potential to harm the colony because of the disruption in thermoregulation. Here, we present a simple and affordable indoor management method utilizing a mylar tent and controlled environmental conditions that allows bees to freely fly without access to outdoor space. This technique permits research labs to successfully keep several colonies persistently active during winter at higher latitudes. Having an extended research period is particularly important for training students, allowing preliminary experiments to be performed, and developing methods. However, we find distinct behavioral differences in honey bees managed in this situation. Specifically learning and thermoregulatory behaviors were diminished in the bees managed in the tent. Therefore, we recommend caution in utilizing these winter bees for full experiments until more is known. Overall, this method expands the research potential on honey bees, and calls attention to the additional research that is needed to understand how indoor management might affect honey bees. 

Abstract Virus symbionts are important mediators of ecosystem function, yet we know little of their diversity and ecology in natural populations. The alarming decline of pollinating insects in many regions of the globe, especially the European honey bee, Apis mellifera, has been driven in part by worldwide transmission of virus pathogens. Previous work has examined the transmission of known honey bee virus pathogens to wild bee populations, but only a handful of studies have investigated the native viromes associated with wild bees, limiting epidemiological predictors associated with viral pathogenesis. Further, variation among different bee species might have important consequences in the acquisition and maintenance of bee-associated virome diversity. We utilized comparative metatranscriptomics to develop a baseline description of the RNA viromes associated with wild bee pollinators and to document viral diversity, community composition, and structure. Our sampling includes five wild-caught, native bee species that vary in social behavior as well as managed honey bees. We describe 26 putatively new RNA virus species based on RNA-dependent RNA polymerase phylogeny and show that each sampled bee species was associated with a specific virus community composition, even among sympatric populations of distinct host species. From 17 samples of a single host species, we recovered a single virus species despite over 600 km of distance between host populations and found strong evidence for isolation by distance in associated viral populations. Our work adds to the small number of studies examining viral prevalence and community composition in wild bees.