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In the late winter or early spring, beekeepers stimulate the colonies to increase the population of bees using different dietary supplements, principally based on carbohydrates and proteins. Honey bees require multiple sources of nectar and pollen to obtain balanced nutrition, so the formulation of effective supplements requires the identification and testing of candidate components, especially at the colony level. In this study, we evaluated the effectiveness of a nutritional supplement (SUP) composed of two important phytochemicals that have been reported to improve honey bee health (abscisic acid (ABA) and p-coumaric acid (CUM)) combined with fish protein hydrolyzate (FPH), and essential omega fatty acids (Ω3/6) in nuclei colonies. We first evaluated the toxicity of SUP compared with the control (sugar syrup) in laboratory bioassays during 96 hours. Then, we tested the effect on the amount of brood, honey, and pollen in bee hives nuclei supplemented with SUP for thirty days. In addition, we quantified and compared the concentration of total proteins in individual honey bees collected at the beginning and at the end of the experiment. The results obtained show that SUP is palatable, nontoxic to Apis mellifera, and significantly increases the amount of open brood and pollen reserves of bee nuclei compared with nuclei feed with sugar syrup. No significant differences were observed, between nuclei feed with SUP and control nuclei, in the amount of honey reserves and total proteins of individual bees. Here, we show the value of a nutritional supplement that combines essential nutritional components and phytochemicals to improve important parameters associated with colony fitness. We expected this nutritional supplement helps beekeepers to develop their colonies in view of the increase of industrial agriculture and the consequent loss of floral resources. [ABSTRACT FROM AUTHOR]

Bombus pauloensis is a native bumble bee species widely distributed over South America and a key pollinator for native plants and commercial crops. This species is affected by pathogens such as Nosema ceranae, Crithidia bombi and Apis mellifera Filamentous Virus (AmFV). This work aims to document the presence and intensity of exogenous pathogens on the native bumble bee B. pauloensis in different periods of the year during spring and summer. Bumble bees were sampled in four study areas with contrasting land uses to preliminary evaluate if anthropization levels can be related to the presence and intensity of pathogens. DNA was isolated from twenty individuals per sampling site and N. ceranae, C. bombi and AmFV pathogens load were quantified by quantitative PCR. The results showed a wide and ubiquitous prevalence of N. ceranae and C. bombi pathogens in all the sampled bumble bees throughout the year, with a pathogens load that did not differ significantly among the sampling sites. AmFV was undetected in any of the individuals analyzed in any sampling site. This suggests that human activities could equally impact all habitats populated by B. pauloensis. Honey bees were detected with a relevant abundance in all the sampling sites and could be one of the main anthropogenic drivers of pathogens spread and host switches in the analyzed sampling sites. This study analyzes the general occurrence of the prevalence and intensity of the pathogens in a native Argentinian bumble bee species and attempts the correlation with the land use [ABSTRACT FROM AUTHOR]

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.

Apis mellifera filamentous virus (AmFV) is a large double stranded DNA virus of honey bees and its prevalence and relationship with other parasites is poorly known. Samples consisted of fifty-one adult bees belonging to eight native species collected using entomological nets in six provinces of Argentina, from 2009 to 2018. Total genomic DNA was extracted from individual bees and a 551 bp fragment of the Bro-N gene of AmFV was amplified by qPCR. In the present work we have reported for the first time both the presence and the wide geographic distribution of AmFV in Argentinian species of native bees. This is the first report of the presence of this virus associated with Xylocopa atamisquensis, X. augusti, X. frontalis, X. spendidula, Bombus pauloensis and Peponapis fervens. Detecting pathogens that could threaten native bee health is of outmost importance to generate both conservation and management strategies.

Varroa destructor (Anderson & Trueman, 2000) causes the most important parasitosis of beekeeping in the world. For this reason, prevention is needed to avoid colony death. The most typical treatments involve synthetic acaricides. However, the use of these acaricides results in the emergence of resistant populations of mites to these products and in the appearances of drug residues in products of the hives. Compounds of essential oils have emerged as an alternative to traditional acaricides; however the toxicity produced by these mixtures is currently poorly explored. The aim of this work was to assess, by means of in vitro tests with adult bees, how acaricidal action and toxic interactions in a binary mixture of essential oil compounds (Thymol, Phellandrene, Eucalyptol, Cinnamaldehyde, Myrcene, and Carvacrol) affect V. destructor. Calculations of LC50 ’s of the individual compounds on A. mellifera and V. destructor made clear that the toxic effect of each compound is different for both species. Thymol and Phellandrene turned out to be lethal for mites at lower concentrations than for bees. The binary mixture of these two substances presented a different toxicity than one produced by each pure compound, as it was highly selective for mites in bioassays at 24 hours through complete exposure to both A. mellifera and V. destructor. These results make such formulations optimal substances to be considered as alternative controls for the parasitosis.

Honey bees collect resin from various plant species and transform it into propolis that is incorporated into the nest. The role of resins in the bee health field is poorly understood. The aim was to evaluate the effects of forced consumption of propolis on the physiological condition and short-term survival of Apis mellifera worker bees. It was tested if the number of circulating hemocytes in hemolymph, the abdominal fat bodies and the hypopharyngeal glands development were affected by the feeding with propolis extracts in laboratory conditions during the warm and the cold seasons. Propolis added to sugar candy was consumed by workers for fourteen days without affecting the bee survival. The number of circulating hemocytes in hemolymph remained constant despite the differential diet during the experiment. However, the development of fat bodies and hypopharyngeal glands was altered by propolis ingestion. The abdominal fat body development in winter bees diminished after fourteen days of propolis consumption, while it increased in summer bees. The hypopharyngeal gland development decreased for the assayed period in workers from both seasons. Our results encourage us to continue exploring this research field and learn how long-term forced ingestion of a plant-derived compound, a non-nutritive substance, can modify physiological bee parameters. A broader understanding of the multiple roles of propolis in the health of the honey bee colonies could be obtained by studying the ways in which it is processed and metabolized and the effect that generates in another physiological responses.

Nosema ceranae is a pathogen of Apis mellifera, which seems to have jumped from its original host Asiatic honey bee Apis ceranae. Nosemosis which affects the honey bee Apis mellifera is caused by two parasitic fungi described as etiologic agents of the disease. Nosema apis was the only microsporidian infection identified in A. mellifera until N. ceranae in Taiwan and Europe. Nosema spp. positive samples of adult worker bees from the Venezuelean state of Lara were determined through light microscopy of spores. Samples were then tested to determine Nosema species (N.apis/N.ceranae) using previously reported PCR primers for the 16S rRNA gene. A multiplex PCR assay was used to differentiate both N. apis and N. ceranae species. Only N. ceranae was found in the analyzed samples and the percentage of infected foragers fluctuated between 18% and 60%.