Wild Honey Bees Research Articles

Index to Titles and Authors/Editors of Books Reviewed

Index to Titles and Authors/Editors of Books Reviewed

Modeling the Potential Global Distribution of Honeybee Pest, Galleria mellonella under Changing Climate.

Simple SummaryThe greater wax moth (GWM) is a common pest of bee colonies throughout the world. This study highlighted the global habitat suitability of GWM using the statistical power of Maxent to model its current and future distribution under climate-change scenarios in 2050 and 2070. Our study shed light on the major environmental factors that manage the habitat suitability of GWM. To the best of our knowledge, this is the first modeling study of wax moths. In brief, this pest can cause severe indirect damage to the global honey market totalling millions of dollars; therefore, developing prompt monitoring or control strategies is advised. Beekeeping is essential for the global food supply, yet honeybee health and hive numbers are increasingly threatened by habitat alteration, climate change, agrochemical overuse, pathogens, diseases, and insect pests. However, pests and diseases that have unknown spatial distribution and influences are blamed for diminishing honeybee colonies over the world. The greater wax moth (GWM), Galleria mellonella, is a pervasive pest of the honeybee, Apis mellifera. It has an international distribution that causes severe loss to the beekeeping industry. The GWM larvae burrow into the edge of unsealed cells that have pollen, bee brood, and honey through to the midrib of the wax comb. Burrowing larvae leave behind masses of webs that cause honey to leak out and entangle emerging bees, resulting in death by starvation, a phenomenon called galleriasis. In this study, the maximum entropy algorithm implemented in (Maxent) model was used to predict the global spatial distribution of GWM throughout the world. Two representative concentration pathways (RCPs) 2.6 and 8.5 of three global climate models (GCMs), were used to forecast the global distribution of GWM in 2050 and 2070. The Maxent models for GWM provided a high value of the Area Under Curve equal to 0.8 ± 0.001, which was a satisfactory result. Furthermore, True Skilled Statistics assured the perfection of the resultant models with a value equal to 0.7. These values indicated a significant correlation between the models and the ecology of the pest species. The models also showed a very high habitat suitability for the GWM in hot-spot honey exporting and importing countries. Furthermore, we extrapolated the economic impact of such pests in both feral and wild honeybee populations and consequently the global market of the honeybee industry.

Non-native plant species integrate well into plant-pollinator networks in a diverse man-made flowering plant community

Urban green areas offer diverse flower resources for pollinators. Yet, the role of non-native plant species in local plant-pollinator networks is understudied. We explored the effects of plant origin, nationwide distribution, flower color and type on flower visitation by wild bees and honey bees as well as the structure of a plant-pollinator network in a botanical garden in Hungary. Honey bee preferred North American plants over Europeans; it had the highest degree and topological centrality value. The network had similar compactness with its simulated removal from the network model. The species richness and abundance of flower-visiting wild bees did not differ among the plants of different origins and flower color and type. Plant species of different origin, nationwide distribution, and flower color and type had the highest number of direct and indirect links. Our results suggest that non-native plant species can integrate well in diverse botanical gardens and wild bees can adopt these new foraging resources.

Gut Bacterial Flora of Open Nested Honeybee, Apis florea

Honeybees are eusocial insects with close interaction with their surrounding environment. Gut microbiota in honeybees play a significant role in host health, biology, and interaction behavior with the surrounding environment. Apis florea, a wild bee, is the most primitive among all honeybees and is indigenous to the Indian subcontinent. Previous reports on reared honeybee species provide information on the gut microbiome. No such studies are reported on the gut microbiota of the wild honeybee species. This study aimed at studying the gut microbiome of the wild honeybee species, A. florea. The study reports the analysis and the identification of gut bacteria in the wild honeybee species, A. florea, employing culture-based and culture-independent methods. Cultured bacteria were identified and characterized by MALDI-TOF MS and 16S rRNA sequencing. A comprehensive analysis and identification of non-culturable bacteria were performed by 16S rRNA amplicon next-generation sequencing. This approach splits gut bacteria into four bacterial phyla, four families, and 10 genera in major. The dominant taxa identified in A. florea belonged to the family Enterobacteriaceae (79.47%), Lactobacillaceae (12.75%), Oxalobacteraceae (7.45%), and Nocardiaceae (0.13%). The prevailing bacteria belonged to Enterobacter, Lactobacillus, Escherichia-Shigella, Massilia, Klebsiella, Citrobacter, Pantoea, Serratia, Rhodococcus, and Morganella genera, belonging to phyla Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. This study observed the occurrence of a few bacteria that are not previously reported for their occurrence in other species of the Apis genus, making this investigation highly relevant with regard to the bee microbiome.

Pesticide exposure of wild bees and honey bees foraging from field border flowers in intensively managed agriculture areas

Bees are critical for food crop pollination, yet their populations are declining as agricultural practices intensify. Pollinator-attractive field border plantings (e.g. hedgerows and forb strips) can increase bee diversity and abundance in agricultural areas; however, recent studies suggest these plants may contain pesticides. Pesticide exposure for wild bees remains largely unknown; however, this information is needed to inform agricultural practices and pesticide regulations meant to protect bees. It is important to determine whether border plantings that attract and support pollinators may also deliver pesticides to them. In this study, we collected various samples for pesticide residue analysis, including: multiple species of wild bees, honey bees, flowers from four types of bee-attractive field border plants, and soil. Silicone bands were also utilized as passive aerial samplers of pesticide residues. The five pesticides detected most frequently across all samples were the insecticide bifenthrin, the herbicides thiobencarb, metolaclor, and propanil, and the fungicide fluopyram. We detected the greatest number of parent pesticides in bands (24), followed by soil (21). Pesticides were also detected in field border plant flowers (16), which do not receive direct pesticide applications, and included many products which were not applied to adjacent field crops. Pesticide concentrations were lower in bees than in flowers but higher in bees than in soils. Pesticide residue per bee (ng/bee) increased with increasing wild bee size, though pesticide concentration (ng/g) did not increase. While honey bees and wild bees contained a similar number and concentration of pesticides overall, pesticide mixtures varied by bee type, and included some mixtures known to cause sublethal effects. The results from this study highlight the benefits of measuring more sample types to capture the total exposome of bees, including a greater range of bee species, as well as the need to consider exposure to pesticides at the landscape level.

Forbs included in conservation seed mixes exhibit variable blooming detection rates and cost‐effectiveness: implications for pollinator habitat design

Although forb‐rich plantings for pollinator habitat are becoming more common, natural resource managers lack insight on the cost‐effectiveness of forbs seeded in private land conservation programs. Additional information on the possible benefits of including more forb species in a mix may help guide the design of future pollinator habitat. We examined the detection of blooming forbs from seed mixes, colonization of non‐seeded blooming forbs, and bee utilization of forbs on private lands enrolled in United States Department of Agriculture (USDA) conservation programs. By obtaining the original seed mixes used on conservation program lands and sampling forbs and bees, we provide a first‐hand evaluation of the cost‐effectiveness of USDA conservation plantings in a field setting. We identified seeded forbs with the highest blooming detection rates and the most common colonizing forbs across 27 sites, the majority of which were considered young conservation plantings. We additionally designated 16 forbs as the most cost‐effective due to their higher‐than‐average blooming detection rate and lower‐than‐average seed cost. We found a positive association between seed mix richness and number of blooming, seeded forbs detected and found a negative association with blooming, non‐native colonizing forbs, which highlights potential benefits of increasing forb richness in seed mixes. However, we did not observe an association between seed mix richness and wild bee or honey bee counts. Examining the cost‐effectiveness of seeded forbs on USDA conservation enrollments and subsequent bee utilization can inform land managers in designing seed mixes for pollinator habitat.

The Diversity Decline in Wild and Managed Honey Bee Populations Urges for an Integrated Conservation Approach

Many parts of the globe experience severe losses and fragmentation of habitats, affecting the self-sustainability of pollinator populations. A number of bee species coexist as wild and managed populations. Using honey bees as an example, we argue that several management practices in beekeeping threaten genetic diversity in both wild and managed populations, and drive population decline. Large-scale movement of hive stocks, introductions into new areas, breeding programs and trading of queens contribute to reducing genetic diversity, as recent research demonstrated for wild and managed honey bees within a few decades. Examples of the effects of domestication in other organisms show losses of both genetic diversity and fitness functions. Cases of natural selection and feralization resulted in maintenance of a higher genetic diversity, including in a Varroa destructor surviving population of honey bees. To protect the genetic diversity of honey bee populations, exchange between regions should be avoided. The proposed solution to selectively breed all local subspecies for a use in beekeeping would reduce the genetic diversity of each, and not address the value of the genetic diversity present in hybridized populations. The protection of Apis mellifera’s, Apis cerana’s and Apis koschevnikovi’s genetic diversities could be based on natural selection. In beekeeping, it implies to not selectively breed but to leave the choice of the next generation of queens to the colonies, as in nature. Wild populations surrounded by beekeeping activity could be preserved by allowing Darwinian beekeeping in a buffer zone between the wild and regular beekeeping area.

Unprecedented Density and Persistence of Feral Honey Bees in Urban Environments of a Large SE-European City (Belgrade, Serbia).

Simple SummaryThe western honey bee, a pollinator species that is essential for modern agriculture and food production sustainability, is under various anthropogenic pressures. In the last few decades, these have led to serious worldwide problems concerning the health and stability of honey bee colonies. The importance of wild or feral honey bees has only recently been recognized, as these populations are crucial for research on the processes that enable their survival under such pressures. Here, we present a case of an unmanaged free-living population of honey bees that, unlike in other known studies, live in a highly populated urban environment. This extraordinarily dense feral honey bee population, which is not directly associated with managed apiaries, provided us with a large dataset of various life history parameters that will considerably fill in the knowledge gaps on unmanaged colonies. Furthermore, we want to underline the importance of citizen science in the data collection process and suggest it as a suitable approach to study feral honey bees in urban landscapes. We believe that highly populated urban landscapes can support and reinforce feral honey bees and that similar citizen science projects should be set up in other urban areas or other countries.It is assumed that wild honey bees have become largely extinct across Europe since the 1980s, following the introduction of exotic ectoparasitic mite (Varroa) and the associated spillover of various pathogens. However, several recent studies reported on unmanaged colonies that survived the Varroa mite infestation. Herewith, we present another case of unmanaged, free-living population of honey bees in SE Europe, a rare case of feral bees inhabiting a large and highly populated urban area: Belgrade, the capital of Serbia. We compiled a massive data-set derived from opportunistic citizen science (>1300 records) during the 2011–2017 period and investigated whether these honey bee colonies and the high incidence of swarms could be a result of a stable, self-sustaining feral population (i.e., not of regular inflow of swarms escaping from local managed apiaries), and discussed various explanations for its existence. We also present the possibilities and challenges associated with the detection and effective monitoring of feral/wild honey bees in urban settings, and the role of citizen science in such endeavors. Our results will underpin ongoing initiatives to better understand and support naturally selected resistance mechanisms against the Varroa mite, which should contribute to alleviating current threats and risks to global apiculture and food production security.

Comparative Study of Antimicrobial Properties of Bee Venom Extracts and Melittins of Honey Bees.

Bee venom (BV), or apitoxin, is a complex substance produced by a gland in the abdominal cavity of bees. The main component of BV is melittin, which is a largely studied substance due to its biological properties. To date, the most well-known bee venom and melittin are derived from domesticated honey bees, while venom and melittin derived from wild honey bees have been under-investigated. Hence, this study primarily reports the antimicrobial activities of bee venom and synthetic melittin derived from four different honey bee species (Apis mellifera, A. cerana, A. dorsata, and A. florea) in Thailand. All the bee venom extracts and melittins showed more robust antibacterial activities against Gram-positive (Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, S. aureus MRSA, and S. epidermidis) than Gram-negative bacteria (Escherichia coli, Klebsiella pneuminiae, and Salmonella typhimurium) or a fungus (Candida albicans), while the synthetic melittins also have antimicrobial activity at higher concentrations than the bee venom extract. Furthermore, the A. cerana venom extract showed the highest activity against the tested bacteria, followed by A. mellifera, A. florea, and A. dorsata. Therefore, A. cerana venom may be further developed for use in medical applications as a potential alternative agent against Gram-positive bacteria and antibiotic-resistant bacteria.

A Survey of Common Pathogens of Apis spp. in Wild Non-Cave Honeybees in Southwest China.

Honeybees are crucial pollinators with significant ecologic value. The decline of wild honeybee populations has been recognized and documented during recent decades. However, the health status of wild non-cave Apis spp., including giant and dwarf honeybees, remains generally unknown. We investigated eight common viruses and five bacterial or fungal pathogens in four wild non-cave honeybee species at 11 locations in Southwest China. As a result, Melissococcus plutonius, the pathogenic agent of European foulbrood, was detected in all the species, and the sequences were identical to the pathogen in managed cave honeybees. Only one virus, black queen cell virus (BQCV), was positive in one dwarf species, Apis florea, in our study. The positive BQCV infected three A. florea colonies in Guangxi Province, with distinct sequences from this virus reported in cave honeybees or in the same host in the nearby Yunnan Province. Although our results indicated a low pathogenic level of common diseases in the wild non-cave Apis spp. in Southwest China, the conservation of these wild pollinators is of importance in light of the noticeable decline in populations and the irreplaceable position of pollination.

Patch utilization and flower visitations by wild bees in a honey bee-dominated, grassland landscape.

Understanding habitat needs and patch utilization of wild and managed bees has been identified as a national research priority in the United States. We used occupancy models to investigate patterns of bee use across 1030 transects spanning a gradient of floral resource abundance and richness and distance from apiaries in the Prairie Pothole Region (PPR) of the United States. Estimates of transect use by honey bees were nearly 1.0 during our 3.5‐month sampling period, suggesting honey bees were nearly ubiquitous across transects. Wild bees more frequently used transects with higher flower richness and more abundant flowers; however, the effect size of the native flower abundance covariate (β^native = 3.90 ± 0.65 [1SE]) was four times greater than the non‐native flower covariate (β^non‐native = 0.99 ± 0.17). We found some evidence that wild bee use was lower at transects near commercial apiaries, but the effect size was imprecise (β^distance = 1.4 ± 0.81). Honey bees were more frequently detected during sampling events with more non‐native flowers and higher species richness but showed an uncertain relationship with native flower abundance. Of the 4039 honey bee and flower interactions, 85% occurred on non‐native flowers, while only 43% of the 738 wild bee observations occurred on non‐native flowers. Our study suggests wild bees and honey bees routinely use the same resource patches in the PPR but often visit different flowering plants. The greatest potential for resource overlap between honey bees and wild bees appears to be for non‐native flowers in the PPR. Our results are valuable to natural resource managers tasked with supporting habitat for managed and wild pollinators in agroecosystems.

Increased compositional heterogeneity of mass‐flowering orchard crops does not promote wild bee abundance in orchards

AbstractDue to increasing difficulties to maintain semi‐natural habitat within agricultural landscapes, management of the agricultural matrix may provide a more realistic approach to support farmland biodiversity and associated ecosystem services. We hypothesize that orchard compositional heterogeneity (OCH), that is, different mass‐flowering crops with sequential blooming periods, may support pollinators through continuous abundance of floral resources. We assessed whether increased OCH at the landscape level had a positive effect on wild bee abundances in sweet cherry and apple orchards during bloom. We monitored 15 sweet cherry and 14 apple orchards in Flanders, Belgium, situated along a gradient of OCH. We performed pollinator surveys during bloom to measure wild bee and honey bee abundance and monitored fruit development to assess fruit set and quality. We found no positive effect of OCH on wild pollinator abundance in our study system. Solitary bees showed contrasting responses between crops. Bumble bees showed no response. Wild pollinator abundance had a positive effect on sweet cherry fruit set and apple seed set. Our results imply that increasing crop compositional heterogeneity solely in terms of orchard crops with a limited difference in bloom phenology may prove to be insufficient to support pollinators. We confirm the importance of wild pollinators for pollination services in horticulture.

Floral resource selection by wild bees and honey bees in the Midwest United States: implications for designing pollinator habitat

Many seed mix recommendations for creating pollinator habitat are in part based on anecdotal evidence or field observations of bees visiting forbs (i.e. use). However, there is limited information on what forbs are preferred by bees, particularly in working landscapes where bee forage may be limited. We examined floral resource selection by wild bees and honey bees on grasslands in the Midwest using a 5‐year dataset containing over 8,000 plant‐bee interactions. We observed wild bees visiting 83 forb species, but only 14 species were significantly selected (i.e. bees visited a plant more than expected based on availability). Approximately 70% of all wild bee visitations were on native flowers, whereas only 20% of all honey bee visitations were on natives. Honey bees visited 70 forb species, but only four forbs were significantly selected. The selection ratio for each forb species was not correlated with proportion of use by wild bees or honey bees, suggesting that bee visitation data alone do not elucidate patterns of forb selection or avoidance. We then compared our resource selection results to forbs recommended by U.S. Department of Agriculture (USDA) for regional pollinator habitat plantings. Many forbs that were selected by bees in our study were also recommended by USDA; however, some USDA‐recommended forbs were selected against by bees. A greater understanding of which floral resources are selected by bees can assist land managers in assessing conservation seed mixes and ultimately provide diverse, season‐long pollinator forage in working landscapes.

Cavity occupancy by wild honey bees: need for evidence of ecological impacts

The European honey bee (Apis mellifera) is managed worldwide for honey production and crop pollination, and is an invasive species in many countries. Wild colonies occupy natural and human‐made cavities and are thought to impact other cavity‐using species. We reviewed documented evidence of wild A mellifera nesting sites globally via a literature review (27 relevant studies) and citizen‐science observations of wild honey bee colonies on iNaturalist (326 observations). Honey bee occupancy rates from published studies were typically low and occupation was often temporary. Citizen‐science data showed that most colonies in cavities had small or narrow entrance holes. Current evidence of perceived competition with honey bees in cavities is largely anecdotal and little is known about the long‐term impacts on survival and reproductive success of other cavity‐occupying species. To guide conservation policy and practice, more empirical research is needed to understand the ecological outcomes of competitive interactions in nesting cavities.

Biodiversity of lactic acid bacteria of wild honey bee and Sumbawa horse milk by using RAPD-PCR

Wild honey bee and Sumbawa horse milk is the local product from West Nusa Tenggara, Indonesia, which has the characteristic of little sour in taste. The sour taste indicates lactic acid bacteria (LAB) existence that has a potential function as probiotics. The objection of this study is analysis of lactic acid bacteria biodiversity from wild honey bee and Sumbawa horse milk by using Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR). The genome of cultured samples from M17 and MRS medium were extracted, then identified by RAPD-PCR with primer (GTG)5 (5-GTGGTGGTGGTGGTG-3). The scoring of DNA fragments was analyzed using the Numerical Taxonomy and Multivariate Analysis System (NTSYS) application. The result show five clusters from a common ancestor indicated the broad diversity of LAB in wild honey bee and Sumbawa horse milk.

Breeding Efforts on Wild Honey Bee Apis cerana Fabr. within Coconut Plantations in Padang Pariaman, West Sumatra

In order to maximize the potential of wild honey bee Apis cerana, there have been ongoing breeding efforts conducted in three coconut plantations in Padang Pariaman, West Sumatra. The searching for wild honey bee colonies was performed in potential sites in Lancang, Batu Gadang and Pakandangan Villages. There were 20 colonies found in the wild and relocated using hive-to-stub method; 10 colonies were then bred in its original sites while other 10 stubs transferred into farm located in Pakandangan Village. To support the breeding efforts, there was inventory survey carried out at the surrounding of breeding farms to list plants that are food sources for honey bee. From total 60 bee hives found, 32 of them built inside the hollow of dead timber, 18 nests existed in living tree crevices and other 10 nests in various hollowing structures. The successfulness of breeding effort using hiving method before transferred to distance farming location reached 76.66%, much higher than letting the stubs in the original location of wild nests (23.34%). Number of honey combs grew on the first month after transferred was variable between 3-9 frames and 124 frames (35.38%), the breadth of comb up until 75%. Plants for food sources were enlisted until 65 species, in which 20 of them categorized as cultivated and year-round flowering plants.

Detection and characterization of wolbachia endosimbiont in wild bee (apis cerena) using the cytohrome C oxidase subunit I gene

Apis cerena; is as wild bee or honey bee, widespread in almost all regions of Indonesia, these bee economic value as the honey it produces. Indonesian people, especially in Tanjung Peropa Southeast Sulawesi who use bees as a honey-producing source maintain honey bees with a honeycomb claim system that lives in hives in forested trees or found in people’s homes. Until now, there is no breeding or breeding business. Wobachia is endosimbiont which was infected Artrophoda, including insects, which can influence the dynamics of these insects population and can reduce insect perform and viability. Therefore, molecular detection of the presence of Wolbachia in Apiscerena is important. The COI gene is a gene proposed as an animal barcode. There is evidence of primer use of the COI gene as a barcode which is often contaminated with Wolbachia COI gene which is not a target. The individual bee was extracted the genome DNA using the CTAB (cetyltrimethyl ammonium bromide) method, and then the cytochrome oxidase gene (COI) was umplified using an animal barcode primer. The amplification results are then sequenced and then characterized. Using Wolbachia COI gene data available on GenBank as a comparison, reconstruction of phylogenetic tree of Wobachian base on COI nucleotide sequences, so the position taxon of Wolbachia shall be determine. Phylogenetic tree reconstruction make with a Neiberjoining method with the Kimura 2-meter models and 1000x boostrapped. The results showed that the Wobachi COI gene was successfully amplified by these primer animal barcode, along 701bp. A proof that wild bees have been infected by Wolbachia. The findings of this study prove that PCR method are very sensitive to be used to detect existenceWolbachia in bees. This also means that the primer used to reveal animal barcodes, specifically vertebrates, can also amplify the Wolbachia gene; a Rickettsia. The gene has special characteristics, namely 633 base pairs (bp) conserved, and 24 bp variable nucleotides. Of these there are 12 nucleotides which unique for Wobachians who infected A.cerena from Tanjung Peropa, Kendari Southeast Sulawesi. Base N composition dominated of Timine. The phylogenetic tree showed that Wolbachia from Apis cerena, is closely related to Wolbachia endosymbiont Hymenoptera, with 99% of boostrapped value.

Coexistence of honeybees with distinct mitochondrial haplotypes and hybridised nuclear genomes on the Comoros Islands.

The honeybee, Apis mellifera, is a globally distributed species that has spread both naturally and by humans across the globe resulting in many natural and secondary contact zones. The geographic isolation of honeybees is likely to contribute to genetic differentiation. Secondary contact has resulted in hybridization at the nuclear genome, but replacement of mitochondrial. Here, we used a mitochondrial marker and 19 microsatellite markers to test for the variations in the mitochondrial and nuclear genomes of honeybee populations on the Comoros islands. We used samples of 160 workers for mtDNA analysis and 288 workers from 16 colonies spread across the three islands for microsatellite analyses. Our results showed that the wild honeybee populations of the Comoros Islands consist of coexisting mitochondrial haplotypes. One belongs to the typical African A-lineage, and the other, the newly described L-lineage, is closely related to Apis koschevnikovi, a honeybee species native to Southeast Asia. The nuclear genomes show complete hybridization, high genetic diversity, and strong differentiation according to the island of origin. Based on our results, we hypothesise that the Asian honeybee could have been transported from Southeast Asia to Madagascar and Comoros via the human migrations that occurred 6000years ago, and has hybridised with African honeybees at the nuclear genome, but maternal ancestry still can be traced using the mtDNA markers. We conclude that mtDNA plays a pivotal role in adaptation to the local environment, with both haplotypes of the honeybees of Comoros contributing significantly to the mito-nuclear coadaptation resulting in maintenance at almost equal frequency.

Possible Spillover of Pathogens between Bee Communities Foraging on the Same Floral Resource.

Simple SummaryFloral resource availability is one of the keys to preserving the health of bee communities. However, flowers also present a risk of pathogen transmission, as infected pollinators could deposit pathogens while foraging, exposing other pollinators to infection via the consumption of contaminated nectar or pollen. Here, we studied, over time, the prevalence of seven viruses in bee communities that share the same small surface of floral resource in order to assess the risk of virus spillover. In total, 2057 bee specimens from 30 species were caught, identified and checked for the presence of viruses. Specimens from the Halictidae family were the dominant wild bees. The prevalence of viruses was quite high: at least one virus was detected in 78% of the samples, and co-infections were frequent. The genetic diversity of the viruses was also investigated to look for the possible association of geographic origin or host with shared ancestry.Viruses are known to contribute to bee population decline. Possible spillover is suspected from the co-occurrence of viruses in wild bees and honey bees. In order to study the risk of virus transmission between wild and managed bee species sharing the same floral resource, we tried to maximize the possible cross-infections using Phacelia tanacetifolia, which is highly attractive to honey bees and a broad range of wild bee species. Virus prevalence was compared over two years in Southern France. A total of 1137 wild bees from 29 wild bee species (based on COI barcoding) and 920 honey bees (Apis mellifera) were checked for the seven most common honey bee RNA viruses. Halictid bees were the most abundant. Co-infections were frequent, and Sacbrood virus (SBV), Black queen cell virus (BQCV), Acute bee paralysis virus (ABPV) and Israeli acute paralysis virus (IAPV) were widespread in the hymenopteran pollinator community. Conversely, Deformed wing virus (DWV) was detected at low levels in wild bees, whereas it was highly prevalent in honey bees (78.3% of the samples). Both wild bee and honey bee virus isolates were sequenced to look for possible host-specificity or geographical structuring. ABPV phylogeny suggested a specific cluster for Eucera bees, while isolates of DWV from bumble bees (Bombus spp.) clustered together with honey bee isolates, suggesting a possible spillover.

Neonicotinoids in the agroecosystem: In-field long-term assessment on honeybee colony strength and microbiome

Bees can be severely affected by various plant protection products (PPP). Among these, neonicotinoid insecticides are of concern as they have been shown to be responsible for extensive honeybee colonies death when released into the environment. Also, sublethal neonicotinoid doses contaminating single honeybees and their colonies (e.g. through contaminated pollen) are responsible for honeybees physiological alterations with probable implication also on microbiome functionality. Honeybees show symbiotic interactions with specific gut bacteria that can enhance the adult host performances. Among the known mechanisms, the modulation of the immune system, the degradation of recalcitrant secondary plant metabolites, pollen digestion, and hormonal signaling, are the most important functional benefits for the host honeybee. To date, few research efforts have aimed at revealing the impact of PPP on the gut microbial community of managed and wild honeybees. The majority of the existing literature relays on cage or semifield tests of short duration for research investigating neonicotinoids-gut microbiome interactions. This research wanted to unravel the impact of two neonicotinoids (i.e. imidacloprid and thiacloprid) in natural field conditions up to 5 weeks of exposure. A long-term impact of neonicotinoids on gut microbial community of honeybees was observed. The alterations affected several microbial genera and species such as Frischella spp., lactobacilli and bifidobacteria, whose shifting is implicated in intestinal dysbiosis. Long-term impact leading to dysbiosis was detected in case of exposure to imidacloprid, whereas thiacloprid exposure stimulated temporary dysbiosis. Moreover, the microbial diversity was significantly reduced in neonicotinoid-treated groups. Overall, the reported results support a compromised functionality of the gut microbial community, that might reflect a lower efficiency in the ecosystemic functionality of honeybees.