Adult Bees Research Articles

The Gut-Brain-Microbiome Axis in Bumble Bees.

The brain-gut–microbiome axis is an emerging area of study, particularly in vertebrate systems. Existing evidence suggests that gut microbes can influence basic physiological functions and that perturbations to the gut microbiome can have deleterious effects on cognition and lead to neurodevelopmental disorders. While this relationship has been extensively studied in vertebrate systems, little is known about this relationship in insects. We hypothesized that because of its importance in bee health, the gut microbiota influences learning and memory in adult bumble bees. As an initial test of whether there is a brain-gut–microbiome axis in bumble bees, we reared microbe-inoculated and microbe-depleted bees from commercial Bombus impatiens colonies. We then conditioned experimental bees to associate a sucrose reward with a color and tested their ability to learn and remember the rewarding color. We found no difference between microbe-inoculated and microbe-depleted bumble bees in performance during the behavioral assay. While these results suggest that the brain-gut–microbiome axis is not evident in Bombus impatiens, future studies with different invertebrate systems are needed to further investigate this phenomenon.

Comparison of long-term changes in size and longevity of bee colonies in mid-west Japan and Maui with and without exposure to pesticide, cold winters, and mites.

Four long-term field experiments in mid-west Japan (Shika) made it clear that extinction of colonies exposed to neonicotinoid was much higher than for colonies exposed to organophosphates. The incidence of hive death for of organophosphate-exposed and control (pesticide-free) colonies was similar. We conducted a field experiment in Maui for 271 days using the same pesticides (dinotefuran: 0.2 ppm, clothianidin: 0.08 ppm, fenitrothion: 1 ppm) as used in Shika with the honeybee, Apis mellifera, colonies without mites. Numbers of adult bees, capped brood, mites and other hive parameters were accurately counted on photographs of combs and on the inside of the hives. All six neonicotinoid (dinotefuran & clothianidin)-exposed colonies failed during the experiment. One of three organophosphate (fenitrothion)-exposed colonies and one of the three control colonies also failed. The findings from Maui, where colonies displayed no mites, provides evidence from Shika, with mites, that neonicotinoids are more hazardous to honeybee colonies than organophosphates. The apparent longevity of honeybee colonies on Maui was estimated by numbers of adult bees and capped brood using a mathematical model previously proposed. Seasonal changes in longevity on Maui differ greatly from changes at Shika, the latter showing distinct seasonal variation. Longevity on Maui remains nearly constant throughout the year with wide variations. At Shika, it increases drastically in winter, by six- to ten fold more than the other seasons. Differences seem to depend on the existence of cold winters and the length of flowering seasons. In a perpetually hospitable environment, small changes in conditions can be sensitively reflected in apparent longevity. Examining wide variations in apparent longevity that are seemingly incoherent, we recognized several differences in apparent longevity between neonicotinoid-exposed and organophosphate-exposed colonies: The colony that failed in after organophosphate-exposure colony group exhibited the longest apparent longevity and the fewest number of newly capped brood, as also was the case in control colonies. Extended longevity when few brood are newly produced is reasonable to maintain the colony from a physiological point of view. Extension of apparent longevity is not seen in neonicotinoid-exposed colonies when the number of newly capped brood is fewer. This finding suggests that neonicotinoid pesticides may inhibit normal apian physiology.

Summer brood interruption as integrated management strategy for effective Varroa control in Europe

Most Varroa induced colony losses occur during the autumn or winter season as a consequence of an elevated Varroa infestation level and an insufficient health status of the adult bees. Even with an initial low Varroa infestation in early spring, critical mite and virus infection levels can be reached before winter if colonies continuously rear brood throughout the whole season. To overcome this challenge, beekeepers can artificially interrupt brood production by suitable management procedures, depending on their type of beekeeping operation. To assess their efficacy, associated workload, and impact on colony development, different methods for brood interruption (queen caging with the combination of oxalic acid treatment, total brood removal, trapping comb technique) were tested during two seasons in 11 locations on 370 colonies in 10 European countries. A protocol was developed to standardize the methods’ application across different environmental conditions. The efficacy of queen caging depended on the mode of oxalic acid application and ranged from 48.16% to 89.57% mite removal. The highest efficacies were achieved with trickling a 4.2% solution (89.57%) and with the sublimation of 2 g of oxalic acid (average of 88.25%) in the broodless period. The efficacy of the purely biotechnical, chemical-free trapping comb and brood removal methods did not differ significantly from the queen caging groups. We conclude that a proper application of one of the described brood interruption methods can significantly contribute to an efficient Varroa control and to the production of honey bee products meeting the highest quality and food-safety standards.

Silent, underground warfare of flies: an endoparasitic bee fly (Diptera: Bombyliidae) larva parasitising a predatory assassin fly (Diptera: Asilidae) larva

AbstractAssassin or robber flies (Asilidae) and bee flies (Bombyliidae) are two of the largest and most diverse fly families with over 7400 and 4700 described species worldwide, respectively. Adult assassin flies are predatory, feeding on smaller insects captured on the wing, and larvae predate on soft‐bodied arthropods in the soil or rotting wood. Adult bee flies feed on nectar and pollen. Almost all bee fly larvae are external or internal parasitoids of other insect larvae, usually in the soil. Although the interaction between bee fly larvae and their hosts has been rarely observed, we recently discovered assassin fly larvae hosting bee fly Lepidanthrax linguatus (Anthracinae: Villini) endoparasitoids in riverine sandy soil in southern NSW, Australia. While bee fly larvae have been known to attack other fly larvae, Asilidae is an uncommon host group. Furthermore, to find bee fly larvae inside the host is even less common because most bee fly larvae are ectoparasitoids. Here we describe and illustrate the host assassin fly (Bathypogon nigrinus: Bathypogoninae) larva and pupa, as well as the first instar bee fly larva (planidium) though careful external examination of the surface of the asilid larva, which is translucent, allowing us to see the internal parasite. This is the first larva and pupa from Bathypogoninae to be described. We also illustrate the bee fly larva in detail based on scanning electron microscopy of a larva in situ, after dissection from the host. Finally, we describe the late instar larval and pupal exuvia of the endoparasitoid. Like other endoparasitoid bombyliid larvae in the Villini, the first instar larva causes the host to produce a breathing tube that surrounds the posterior half of the parasitoid, allowing the parasitoid to maintain contact with atmospheric oxygen.

A three-year large scale study on the risk of honey bee colony exposure to blooming sunflowers grown from seeds treated with thiamethoxam and clothianidin neonicotinoids

Despite the restriction of the use of neonicotinoids in the EU, including thiamethoxam and clothianidin, the debate over their risk on honey bees has not been fully settled. This study presents results of a three-year study working with 180 honey bee colonies in ten replicates. Colonies were sorted into three treatments (60 colonies per treatment) exposed to sunflower blooms grown from seeds treated with thiamethoxam, clothianidin and a non-treated control. Each colony was assessed at six moments: one before to exposition to sunflower, two during the exposition (short-time risk), two after exposition (medium-time risk) and one after wintering (long-time risk). The health and development of the colonies were assessed by monitoring adult bee population, brood development, status of the queen, food reserves and survival. No significant difference among treatments when raw data was considered. However, when evolution from initial status of the colony was evaluated, a significant difference was observed from the first week of exposure to sunflower blooms. In this period, the number of adult bees and the amount of brood were slightly lower in the bee hives exposed to neonicotinoids, although such differences disappeared in subsequent evaluations. The concentration of residues in samples of beebread and adult bees was at the level of ng·g−1. Magnitude of the effect of the treatment factor on the variability of colony health and development related parameters was low. The most important factor was the hive, followed by the replicate and year, and to a lesser extent the initial strength of the colonies.

Composition and Efficacy of a Natural Phytotherapeutic Blend against Nosemosis in Honey Bees

Honey bees are essential to sustaining ecosystems, contributing to the stability of biodiversity through pollination. Today, it is known that the failure of pollination leads irremediably to the loss of plant cultures and, as a consequence, inducing food security issues. Bees can be affected by various factors, one of these being Nosema spp. which are protozoans specifically affecting adult honey bees and a threat to bee populations around the world. The composition of the phytotherapeutic product (Protofil®) for treating nosemosis was analyzed from a biochemical point of view. The most concentrated soluble parts in the phytotherapeutic association were the flavonoids, most frequently rutin, but quercetin was also detected. Additionally, the main volatile compounds identified were eucalyptol (1.8-cineol) and chavicol-methyl-ether. To evaluate the samples’ similarity–dissimilarity, the PCA multivariate statistical analysis, of the gas-chromatographic data (centered relative percentages of the volatile compounds), was applied. Statistical analysis revealed a significant similarity of Protofil® with the Achillea millefolium (Yarrow) samples and more limited with Thymus vulgaris (Thyme) and Ocimum basilicum (Basil), and, respectively, a meaningful dissimilarity with Taraxacum officinale (Dandelion). The results have shown a high and beneficial active compounds concentration in the analyzed herbs. High similarity with investigated product recommending the Protofil®, as the treatment compatible with producing organic honey.

Electrotarsogram responses to synthetic odorants by Varroa destructor, a primary parasite of western honey bees (Apis mellifera).

Olfaction is a key sensory modality for many arthropods and could be used as a tool in pest management through manipulation of pest behavior. Management of Varroa destructor, important parasitic mites of honey bees, could be improved through better understanding of the chemical ecology of this host-parasite relationship. We refined techniques of mounting mites to obtain electrophysiological recordings (electrotarsograms) of their responses to synthetic odor stimuli. Results of 271 electrotarsogram recordings from V. destructor revealed responses to 10 odorants relative to solvent controls. Electrotarsogram responses to methyl palmitate, ethyl palmitate, and 2-heptanol were highest at the lowest stimulus loading (10ng) we tested, suggesting that V. destructor may have acute sensitivity to low concentrations of some odors. Results suggest that odorant origin (e.g., methyl oleate from honey bee larvae, geraniol from adult honey bee alarm pheromone, and α-terpineol, a plant secondary metabolite) can influence the degree of electrophysiological response. Varroa destructor tended to be more responsive to known attractants and repellents relative to previously unexplored odorants and some repellent terpenes. Electrotarsograms offer the potential for screening odors to determine their importance in V. destructor host detection.

Young Honeybee (Apis Mellifera Bandasii) Queens Perform Better than Old Ones

A productivity of queen bee depends on several factors. Queen age is one of the most important factors affecting queen’s, as well as colony performance. The study was conducted to determine the effects of queen ages on performances of honeybee ( Apis mellifera ) colonies. The queens were reared from local honeybee, Apis mellifera bandasii ( A. m. bandasii ); nuclei colonies were formed and then transferred to standard Langstroth hives when all the frames of the nuclei boxes were occupied with brood and adult bees. Performances of the colonies headed by the new queens were evaluated over three years. Brood area, number of queen cell cups started and swarm queen cells constructed, number of empty cells/100 cells/per colony (brood solidness) and honey yield per harvest were determined every active season for three consecutive years. Colonies headed by 1-, 2- and 3-year-old queens produced 4721.43 ± 511.85, 5523.08 ± 490.07 and 3433.82 ± 413.83 cm 2 sealed brood, and constructed 0.07 ± 0.07, 2.23 ± 0.52 and 9.90 ± 1.89 queen cell cups and swarm cells/colony with 1.86 ± 0.38, 2.40 ± 1.65 and 8.85 ± 2.52 empty cells/100 cells/per colony, respectively. Honey harvested from 1- and 3-year-old queen colonies averaged 13.34 ± 1.11 and 10.50 ± 2.04 kg/colony/harvest, respectively. The colonies headed by 1-, and 2-year-old queens had more brood areas, better brood solidity, less number of queen cells but no significant differences in honey production compared to colonies headed by 3-year-old queens. Our results indicate that queen age has a significant effect on colony performances, suggesting that requeening every three years is adequate for our local honeybee colonies. Keywords : Apis mellifera , Queen age, Brood rearing, Swarm queen cells, Queen cell cups DOI: 10.7176/JBAH/10-13-05 Publication date: July 31 st 2020

Poor hive thermoregulation produces an Allee effect and leads to colony collapse

In recent years the honey bee industry has been experiencing increased loss of hives. The accumulation of multiple stressors on a hive potentially drives hive loss in various ways, including winter loss and colony collapse disorder. One of these stressors is the breakdown of thermoregulation inside the hive. For pupae to develop correctly into healthy adult bees, the temperature within the hive must be regulated by the hive bees to within a narrow range that ensures optimal development. Suboptimal development in adults affects their brain and flight muscles so bees becomes inefficient foragers with shorter life spans. We model the effect of thermoregulation on hive health using a system of delay differential equations that show that thermoregulatory stress has the capacity to drive colony loss in the model via a saddle-node bifurcation with an associated Allee effect.

Deformed wing virus type a and b in managed honeybee colonies of Argentina.

Apis mellifera is infected by more than 24 virus species worldwide, mainly positive-sense, single-stranded RNA viruses of the Dicistroviridae and Iflaviridae families. Among the viruses that infect honey bees, Deformed wing virus is the most prevalent and is present as three master variants DWV-A, B, and C. Given that the ectoparasitic mite Varroa destructor vectors these virus variants, recombination events between them are expected, and variants and their recombinants can co-exist in mites and honeybees at the same time. In this study, we detect, through RT-qPCR, the presence of DWV-A and B in the same samples of adult bees from colonies of Argentina. Total RNA was extracted from pools of ten adult bees from 45 apiaries distributed across the main beekeeping Provinces of Argentina (Buenos Aires, Santa Fe, Córdoba, Santiago del Estero, Río Negro, and Mendoza); then RT-qPCR reactions were performed to detect DWV-A and B, with specific primer pairs. After the amplifications, PCR products (204 and 660 bp amplicons for DWV-B, and ~250 bp for DWV-A) were purified and sequenced to verify that they corresponded to reported sequences, analyzing them using the Blast software. Of the 45 samples analyzed by RT-qPCR, over 90% were infected with DWV-A and 47% were also positive for DWV-B, where it was found in high prevalence specifically in colonies of A. mellifera of the Buenos Aires Province. Future studies will determine the impact of this type of the virus and its ability to recombine with the other DWV types in the apiaries of our country.

Methionine as a methyl donor regulates caste differentiation in the European honey bee (Apis mellifera).

Nutrition contributes to honey bee caste differentiation, but the role of individual nutrients is still unclear. Most essential amino acid contents, except that of methionine (Met), are greater in royal jelly than worker jelly. After ∼3.5 d, the Met content in the latter was slightly greater than in the former. Met is the major raw material used in the synthesis of S-adenosyl-L-methionine, an active methyl donor for DNA methylation, which is an epigenetic driver of caste differentiation. Here, we tested whether Met regulates caste differentiation in honey bees by determining its effects on the caste development of bees receiving four diets: the basic, basic + 0.2% Met, basic + 0.2% Met + 20 mg/kg 5-azacytidine, and basic + 20 mg/kg 5-azacytidine. The presence of Met decreased the adult bee body length and the numbers of ovarioles, indicating that Met may direct the development of female larvae toward worker bees. The upregulated expression of SAMS, Dnmt1, and Dnmt3 caused by Met exposure in 4-d-old larvae indicated that the worker-inductive effects of Met may occur through the promotion of DNA methylation. We investigated the co-effects of Met and glucose on bee development, and found that the effects of an increased glucose level on the number of ovarioles and body length did not strengthen the worker-inductive effects caused by Met. Our results contribute to caste development theory and suggest that Met-as a methyl donor-plays a regulatory, but not decisive, role in caste differentiation.

GASTROINTESTINAL BACTERIAL FLORA IN HONEY BEES

Bal arılarının (Apis mellifera) gastrointestinal sisteminde, mikroflora veya mikrobiyota olarak adlandırılan, çeşitli mikrobiyal tehditlere karşı korunmada, bazı metabolik faaliyetlerinde ve arı mahsullerinin üretiminde rol oynayan, arı bağışıklık sisteminde güçlü etki mekanizmalarına sahip, özgün bir mikroorganizma koleksiyonu bulunur. Özellikle yetişkin bal arıları çok zengin bir mikrofloraya sahiptirler. Arı sağlığının korunmasında en önemli ve dikkat çekici faktör, sahip oldukları bu mikrofloradır.Bal arıları (Apis mellifera) insanlar gibi toplu halde yaşar ve kovanda yaşamın devamlılığını sağlamak için iş birliği içinde çalışır. Üretken kolonilerde mikrobiyotadaki çeşitlilik artışı, arının gelişimsel yaşından beslenmesine, kovanın bulunduğu coğrafi konumdan iklim değişikliğine kadar çeşitli faktörlere bağlıdır. Bu bakteriyel topluluk kompozisyonundaki çeşitlilik azlığının da arının mevcut üretkenliğini olumsuz yönde etkileyebileceği belirtilmektedir. Bu derleme, arı yaşamı için büyük önem arz eden bağırsak temel mikroflorasının çeşitliliğini, edinim yollarını, arının gastrointestinal sistemindeki özel kolonizasyonunu ve bal arısı için fayda mekanizmalarını açıklamaktadır.

A new ingestion bioassay protocol for assessing pesticide toxicity to the adult Japanese orchard bee (Osmia cornifrons)

Adopting an Integrated Pest and Pollinator Management strategy requires an evaluation of pesticide risk for pollinator species. For non-Apid species, however, the standardized ingestion assays are difficult to implement. This hinders the consideration of non-Apid species in farm management strategies and government regulatory processes. We describe a new method for a mason bee, Osmia cornifrons, which is an important pollinator of apples and other fruit crops. Our approach overcomes high control mortality seen in other bioassay protocols and expands testing to include males as well as females. The new pesticide toxicity assessment protocol showed that (1) a group feeding method is optimum even though there is no trophallaxis, (2) males had better tolerance to pesticides although they are smaller, and (3) pesticides can cause additional mortality after the standard 48 h assessment time specified by European Food Safety Authority and U.S. Environmental Protection Agency.

Interaction of Varroa destructor and Sublethal Clothianidin Doses during the Larval Stage on Subsequent Adult Honey Bee (Apis mellifera L.) Health, Cellular Immunity, Deformed Wing Virus Levels and Differential Gene Expression.

Honeybees (Apis mellifera L.) are exposed to many parasites, but little is known about interactions with abiotic stressors on their health, particularly when affected as larvae. Larvae were exposed singly and in combination to the parasitic mite Varroa destructor and three sublethal doses of the neonicotinoid insecticide clothianidin to evaluate their effects on survivorship, weight, haemocyte counts, deformed wing virus (DWV) levels and gene expression of the adult bees that subsequently developed. Clothianidin significantly reduced bee weight at the highest dose and was associated with an increase in haemocyte counts at the lowest dose, whereas V. destructor parasitism increased DWV levels, reduced bee emergence, lowered weight and reduced haemocyte counts. An interaction between the two stressors was observed for weight at emergence. Among the differentially expressed genes (DEGs), V. destructor infestation resulted in broader down-regulatory effects related to immunity that was often shared with the combined stressors, while clothianidin resulted in a broader up-regulatory effect more related to central metabolic pathways that was often shared with the combined stressors. Parasites and abiotic stressors can have complex interactions, including additive effects on reduced weight, number of up-regulated DEGs and biological pathways associated with metabolism.

Pathogenicity of aerobic bacteria isolated from honeybees (Apis mellifera) in Ordu Province

The honeybee (Apis mellifera) is an important pollinator insect. Any pathogenic infection in this beneficial insect is undesirable. In this study, bacterial diversity in beehives was investigated to determine the potential of pathogenic bacteria in honeybees. To do this, bacterial isolations were carried out from dead and diseased adult bees collected from 9 districts in Ordu Province in Turkey.Twenty species of pathogenic bacteria, 18 of which were nonsporeforming Staphylococcus lentus, Klebsiella oxytoca, Citrobacter freundii, Leucanostoc mesenteroides ssp. cremoris, Kocuria rosea, Kocuria kristinae, Sphingomonas paucimobilis slashline, Burkholderia cepacia, Leucanostoc mesenteroides ssp. dextranicum,Hafnia alvei, Escherichia coli, Aeromonas salmonicida, Citrobacter braakii, Pantoea agglomerans, Streptococcus equi ssp. zooepidemicus, Staphylococcus pseudintermedius, Staphylococcus lugdunesis and Staphylococcus vitulinus and 2 sporeforming Bacillus licheniformis and Paenibacillus polymyxa, were isolated and identified from the honeybees. The infectivity of these bacteria were also documented with bioassay experiments on the healthy bees.The highest insecticidal effectwas determinedwith Bacillus licheniformis (84%), Escherichia coli (84%), and Streptococcus equi ssp. zooepidemicus (80%) on the adult honeybees.This result confirms that the honeybee contains a very large number of bacterial species and that the majority of them are pathogenic for the species in Turkey. In addition, some of the entomopathogenic bacteria used for biological control can have negative impact on this economically important insect.

Effects of Bacterial Cell-Free Supernatant on Nutritional Parameters of Apis Mellifera and Their Toxicity Against Varroa Destructor

Abstract Apis mellifera L. is an essential pollinator that is currently being affected by several stressors that disturb their ecological function and produce colony losses. Colonies are being seriously affected by the ectoparasitic mite Varroa destructor. The relationship between stressors and bee symbionts is being studied in order to enhance bee health. The goal of this study was to evaluate the effect of cell-free supernatants (CFSs) produced by Lactobacillus johnsonii AJ5, Enterococcus faecium SM21 and Bacillus subtilis subsp. subtilis Mori2 on A. mellifera nutritional parameters and their toxicity against V. destructor. Toxicity and survival bioassays were conducted on adult bees with different concentrations of CFSs. Nutritional parameters such as soluble proteins and fat bodies in abdomens were measured. Varroa destructor toxicity was analyzed by a contact exposure method and via bee hemolymph. At low concentrations, two of CFSs tends to enhance bee survival. Remarkably fat bodies maintained their levels with all CFS concentrations in the abdomens, and soluble protein increased at a high concentration of two CFSs. Toxicity against V. destructor was observed only via hemolymph, and results were in agreement with the treatment that produced an increase in bee proteins. Finally, CFS produced by L. johnsonii AJ5 could be a promising natural alternative for strengthening bee health.

A Modified Standardized Method to Extract and Store Insect Hemolymph with Use of a Glass Capillary

Abstract Hemolymph is the “blood” circulating in the entire insect body. Analysis of this fluid gives information about the condition of the insect. The most precise analyses are conducted on insects’ hemolymph suspended in 0.6% physiological saline (NaCl). Most current hemolymph extraction methods are either difficult or do not provide pure material, the contamination of collected insect “blood” can change results. This study aimed to develop a technique for extract hemolymph, both easy and without risk of contaminating derived material. The presented method is a modification of available ways to extract, store and transport hemolymph with the use of a glass capillary. For the development of this technique, adult worker honey bees (Apis mellifera L.) were used. The method required such basic equipment as a glass capillary, sterile tweezer, Eppendorf tube and physiological saline. The collected hemolymph were frozen and hence sent in a glass capillary to another laboratory for analysis.

Comparison of Different Pollen Substitutes for the Feeding of Laboratory Reared Bumble Bee (Bombus Terrestris) Colonies

Abstract In bumble bee colonies, pollen is the only protein source for larval feeding and its shortage causes a distress in larval development. Adult bumble bees need pollen for the development of glands and the reproductive system. In bumble bee rearing, honey bee collected pollen is used as the main protein source, either as fresh-frozen or dried pellets, and pollen provisioning is the most problematic and expensive aspect of mass rearing. In honey bee breeding, pollen substitutes are used during the period of food shortage or to stimulate colony strength. We tested different protein diets (five commercial pollen substitutes and two natural protein sources) for the maintenance of bumble bee colonies in captivity. We further mixed Feedbee®, one of the substitutes that gave the best results, with different amounts of pollen to evaluate the optimal amount needed for the whole colony development. Although none of the pure protein diets alone were adequate, diets with a 1 to 1 and 1 to 3 ratio of Feedbee to pollen were both suitable for colony development and queen production. The colony consumed between 2 and 4 g per day of the Feedbee mixed diets, corresponding to a protein consumption of 0.75–0.85 g day−1. Nevertheless, the consumption rate of the pure pollen showed that a mean amount of protein between 0.4 and 0.5 g day−1 was enough to allow colony development indicating the suitability of Feedbee mixed diets.

Mode of Transmission Determines the Virulence of Black Queen Cell Virus in Adult Honey Bees, Posing a Future Threat to Bees and Apiculture.

Honey bees (Apis mellifera) can be infected by many viruses, some of which pose a major threat to their health and well-being. A critical step in the dynamics of a viral infection is its mode of transmission. Here, we compared for the first time the effect of mode of horizontal transmission of Black queen cell virus (BQCV), a ubiquitous and highly prevalent virus of A. mellifera, on viral virulence in individual adult honey bees. Hosts were exposed to BQCV either by feeding (representing direct transmission) or by injection into hemolymph (analogous to indirect or vector-mediated transmission) through a controlled laboratory experimental design. Mortality, viral titer and expression of three key innate immune-related genes were then quantified. Injecting BQCV directly into hemolymph in the hemocoel resulted in far higher mortality as well as increased viral titer and significant change in the expression of key components of the RNAi pathway compared to feeding honey bees BQCV. Our results support the hypothesis that mode of horizontal transmission determines BQCV virulence in honey bees. BQCV is currently considered a benign viral pathogen of adult honey bees, possibly because its mode of horizontal transmission is primarily direct, per os. We anticipate adverse health effects on honey bees if BQCV transmission becomes vector-mediated.

Chronic oral exposure of adult honey bees to PPPs: sensitivity and impact analysis of EFSA Bee GD

Chronic oral exposure of adult honey bees to PPPs: sensitivity and impact analysis of EFSA Bee GD