Fall Treatment with Fumagillin Contributes to an Overwinter Shift in Vairimorpha Species Prevalence in Honey Bee Colonies in Western Canada.

(1) Background: Microsporidiosis (nosemosis) is an intestinal disorder of adult honey bees caused by the microsporidian pathogens Vairimorpha apis and Vairimorpha ceranae. In Canada, fumagillin is an approved antibiotic used to treat this disease. However, the recommended dosage is based on efficacy studies for V. apis, the native pathogen in European honey bees. Since the detection of V. ceranae in Apis mellifera, V. ceranae became more prevalent in managed European honey bees and seems to have replaced V. apis due to yet unknown reasons. (2) Methods: This colony study investigated the efficacy of fumagillin administered in the fall to colonies infected with both V. apis and V. ceranae and its effects on the Vairimorpha species' prevalence overwinter. Spore loads in control and fumagillin-treated colonies were analysed by microscopy; Vairimorpha species prevalence was determined molecularly and infection and treatment effects on colony productivity were assessed. (3) Results: Fall fumagillin treatment was associated with a temporary reduction in spore load, but there was no difference in spore loads between treated and control colonies the following spring. Interestingly, fumagillin-treated colonies had a significantly greater prevalence of V. ceranae relative to V. apis the following spring, suggesting fumagillin is less effective in controlling V. ceranae.

Conservation of Local Honeybees (Apis mellifera L.) in Southeastern Turkey: A Preliminary Study for Morphological Characterization and Determination of Colony Performance.

The aim of this study was to investigate the morphological traits and colony performance parameters of local honeybees of the Adiyaman province for future breeding programs. The study was carried out in 2019-2020; a total of 39 colonies were obtained from 13 apiaries in 5 districts, which represented local honeybees, and they were placed in an isolated area. At the same time, 835 worker bees representing local honeybees were assessed for 21 morphological features. There was a difference between the district groups according to the morphological traits (p < 0.05). In terms of the morphological characteristics of honeybees, the correct classification rate to their original groups was determined to be 65.1%. The difference between the district groups was statistically significant regarding the number of frames covered with bees, brood area, and hygienic behavior (p < 0.05). The average weight at the emergence of queens according to district groups and flight activity was found to be significant according to the periods (p < 0.01). As a result, homogeneous honeybees can be found in provinces when considering morphological characteristics. Although colony performance values are low, it is essential to protect the bees' genetic material given their ability to adapt to arid climates and insufficient flora.

Influence of Probiotic Feed Supplement on Nosema spp. Infection Level and the Gut Microbiota of Adult Honeybees (Apis mellifera L.).

Honeybees' gut microbiota can provide new valuable access into the pathogenesis-related factors included in infections. Hence, we researched the presence and comparison of gut microbiota groups in control and Nosema spp.-infected honeybee colonies through high-throughput sequencing of the 16S rRNA. As the newest approach in apiary management, we hypothesize that the EM® probiotic for bees could have an important role in therapeutic and immunomodulatory effects on honeybee colonies. The aim of this study was to estimate its impact on the gut microbiota composition of adult honeybees. The major genera were detected, where Lactobacillus was the most abundant genus, followed by Gilliamela, Snodgrassella, and Bifidobacterium. Inoculation with Nosema spp. spores made the relative proportions of Bifidobacterium lower, which was ameliorated by EM® for bees' application. In addition, EM® for bee applied treatments suppressed the increase in the number of Nosema spp. spores. This result points out that continuous EM® for bees treatment shall change bees' gut microbiome composition and mitigate the influence of Nosema spp. infection. Snodgrassella alvi was a major member of the honeybee gut microbiota and may be significantly increased by long-term treatment with EM® for bees. Toward these results, it is possible that EM® for bees treatment will protect honeybees from herbicide glyphosate negative effects in agricultural fields by improving microbiome and immune functions.

Plant-based supplement containing B-complex vitamins can improve bee health and increase colony performance.

It is common knowledge that nutritive stress resulting from decreased diversity and quality of food, pollution of food sources and beekeeping errors may lead to increased susceptibility of bees to pathogens and pesticides. The dearth of adequate food is frequently compensated with supplements. Thus, this research was aimed to study the effects of the plant-based supplement B + on colony strength (assessed according to open and sealed brood area, honey and pollen/bee bread reserves, and the number of adult bees). In addition, Nosema ceranae spores and viruses were quantified and the level of infestation with Varroa destructor assessed. The experiment was conducted in late summer and early spring. In colonies which were given B + in feed a significant increase (p < 0.05) in the parameters of colony strength were noticed in comparison to the control (colonies fed on sugar syrup). Moreover, it was proven that the bees from these colonies had significantly lower (p < 0.05) N. ceranae spore counts, and acute bee paralysis, deformed wing and sacbrood virus loads. Our results suggest that the addition of B + supplement to the colonies provide them with nutrients, contribute to their strengthening, might prevent nutritive stress and increase the success of bees in combating pathogens.

Urbanisation is associated with reduced Nosema sp. infection, higher colony strength and higher richness of foraged pollen in honeybees.

Bees are vital pollinators, but are faced with numerous threats that include loss of floral resources and emerging parasites amongst others. Urbanisation is a rapidly expanding driver of land-use change that may interact with these two major threats to bees. Here we investigated effects of urbanisation on food store quality and colony health in honeybees (Apis mellifera) by sampling 51 hives in four different land-use categories: urban, suburban, rural open and rural wooded during two seasons (spring and autumn). We found positive effects of urban land use on colony strength and richness of stored pollen morphotypes, alongside lower late-season Nosema sp. infection in urban and suburban colonies. Our results reveal that honeybees exhibit lower colony performance in strength in rural areas, adding to the growing evidence that modern agricultural landscapes can constitute poor habitat for insect pollinators.

High Load of Deformed Wing Virus and Varroa destructor Infestation Are Related to Weakness of Honey Bee Colonies in Southern Spain.

Many factors, including pathogens, contribute to the continuing losses of colonies of the honey bee Apis mellifera, which has led to steady population decline. In particular, colony losses have been linked to deformed wing virus (DWV) and the Varroa destructor mite. To clarify the potential role of these two pathogens in honey bee colony weakening and loss, we sampled colonies in southern Spain during a 21-month period and analyzed the samples for loads of four viruses and varroa. Loads of DWV and black queen cell virus as well as varroa infestation negatively correlated with colony vigor as measured using the subjective colony strength method. Logistic regression identified varroa and DWV as the main factors involved in colony weakening. Our results confirm that varroa and DWV play a key role in triggering colony weakening in southern Spain and provide evidence that experienced beekeepers' and technicians' assessments of colony vigor can accurately estimate colony strength.

Laurus nobilis L. Extracts against Paenibacillus larvae: Antimicrobial activity, antioxidant capacity, hygienic behavior and colony strength.

The aim of this work was to compare the antimicrobial activity against Paenibacillus larvae and the antioxidant capacity of two Laurus nobilis L. extracts obtained by different extraction methods. The hydroalcoholic extract was moreover added as supplementary diet to bees in field conditions to test behavioural effects and colony strength. Both laurel extracts were subjected to different phytochemical analysis to identify their bioactive compounds. Antimicrobial activity was analyzed by the minimal inhibitory concentration (MIC) determination by means the agar dilution method. The hydroalcoholic extract (HE) was able to inhibit the bacterial growth of all P. larvae strains, with 580 µg/mL mean value. This better antibacterial activity in relation to the essential oil (EO) could be explained by the presence of some phenolic compounds, such as flavonoids, evidenced by characteristic bands resulting from the Fourier Transform Infrared Spectroscopy (FTIR) analysis. Antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging ability and ferric reducing antioxidant power (FRAP) assays. The HE showed the highest antioxidant activity as measured by DPPH, with IC50 values of 257 ±â€¯12 µg/mL. The FRAP assay method showed that the HE was 3-fold more effective reducing agent than the EO. When the bee colonies were supplied with laurel HE in sugar paste an improvement in their general condition was noticed, although neither the hygienic behavior nor the proportions of the breeding cells varied statistically due to the treatment. In conclusion, the inhibition power against P. larvae attributable to the phenolic compounds, the antioxidant capacity of the HE, and the non-lethal effects on adult honey bees on field trials suggest the HE of laurel as a promising substance for control American foulbrood disease.

Honey bee viruses in Serbian colonies of different strength.

Protection of honey bees is of great economic importance because of their role in pollination. Crucial steps towards this goal are epidemiological surveys of pathogens connected with honey bee losses. In this study deformed wing virus (DWV), chronic bee paralysis virus (CBPV), acute bee paralysis virus (ABPV) and sacbrood virus (SBV) were investigated in colonies of different strength located in five regions of Serbia. The relationship between colony strength and virus occurrence/infection intensity were assessed as well as the genetic relationship between virus sequences from Serbia and worldwide. Real-time RT-PCR analyses detected at least one virus in 87.33% of colonies. Single infection was found in 28.67% colonies (21.33%, 4.00%, 2.67% and 0.67% in cases of DWV, ABPV, SBV and CBPV, respectively). In the majority of colonies (58.66%) more than one virus was found. The most prevalent was DWV (74%), followed by ABPV, SBV and CBPV (49.30%, 24.00% and 6.70%, respectively). Except for DWV, the prevalence of the remaining three viruses significantly varied between the regions. No significant differences were found between colony strength and either (i) the prevalence of DWV, ABPV, SBV, CBPV and their combinations, or (ii) DWV infection levels. The sequences of honey bee viruses obtained from bees in Serbia were 93-99% identical with those deposited in GenBank.

The effect of Agaricus brasiliensis extract supplementation on honey bee colonies

ABSTRACT This study was done to discover any beneficial effect of a medicinal mushroom Agaricus brasiliensis extract on the honey bee. Firstly, a laboratory experiment was conducted on 640 bees reared in 32 single-use plastic rearing cups. A. brasiliensis extract proved safe in all doses tested (50, 100 and 150 mg/kg/day) irrespective of feeding mode (sugar syrup or candy). Secondly, a three-year field experiment was conducted on 26 colonies treated with a single dose of A. brasiliensis extract (100 mg/kg/day) added to syrup. Each year the colonies were treated once in autumn and twice in spring. The treatments significantly increased colony strength parameters: brood rearing improvement and adult population growth were noticed more often than the increase in honey production and pollen reserves. These positive effects were mainly observed in April. In conclusion, A. brasiliensis extract is safe for the bees and helps maintaining strong colonies, especially in spring.

Screening alternative therapies to control Nosemosis type C in honey bee (Apis mellifera iberiensis) colonies.

Nosemosis type C caused by the microsporidium Nosema ceranae is one of the most widespread of the adult honey bee diseases, and due to its detrimental effects on both strength and productivity of honey bee colonies, an appropriate control of this disease is advisable. Fumagillin is the only veterinary medicament recommended by the World Organization for Animal Health (OIE) to suppress infections by Nosema, but the use of this antibiotic is prohibited in the European Union and few alternatives are available at present to control the disease. In the present study three therapeutic agents (Nosestat®, Phenyl salicylate and Vitafeed Gold®) have been tested to control N. ceranae infection in honey bee colonies, and have been compared to the use of fumagillin. None of the products tested was effective against Nosema under our experimental conditions. Low consumption of the different doses of treatments may have had a strong influence on the results obtained, highlighting the importance of this issue and emphasizing that this should be evaluated in studies to test therapeutic treatments of honey bee colonies.