Epidemiological study of honeybee pathogens in Europe: The results of Castilla-La Mancha (Spain)

As a part of a Pilot Monitoring Program of honey bee health coordinated by the EURL (European Union Reference Laboratory) and according to the criteria established for Spain, 14 apiaries in Castilla-La Mancha were selected at random and sampled during the autumns of 2012-2014 to identify the most prevalent nosogenic agents, potentially those related to the honey bee colony collapse phenomenon. In all the apiaries studied, Nosema ceranae was the most prevalent pathogen detected over the three years, confirming the worldwide spread of this microsporidian, a pathogen that negatively affects honey bee health at an individual and colony level. Trypanosomatids were also very prevalent in honey bee colonies, although the majority of Trypanosomatids detected were not Crithidia mellificae but rather the genetically distinct Lotmaria passim lineage. We also detected Varroa destructor mites, and the particularly high prevalence in 2014 suggests a possible problem regarding mite control in field conditions that requires attention. In agreement with data from other regions, the BQCV and DWV were the most prevalent viruses in honey bee colonies and thus, the Varroa-DVW interaction may be an important cause of bee colony mortality. While there was little evidence of a relationship between the BQCV virus and N. ceranae under field conditions during 2012, this was not the case in 2013 and 2014. Finally, the AKI-complex or LSV-complex was not detected. The information obtained in this study should help orientate future plans for honey bee disease control

Prevalencia de los principales agentes patógenos de Apis Mellifera Iberiensis en la cabaña apícola española

Las abejas melíferas son susceptibles a una amplia variedad de enfermedades y amenazas medioambientales. El objetivo principal de este estudio fue detectar aquellos agentes patógenos relacionados con la pérdida de colonias de abejas melíferas en España utilizando para ello técnicas moleculares basadas en la reacción en cadena de la polimerasa (PCR). Para ello se realizó un estudio nacional durante los años 2006 y 2007. Los resultados obtenidos muestran una alta detección de Varroa destructor (haplotipo Coreano) y Nosema ceranae, una relevante prevalencia Acarapis woodi y una baja detección de Nosema apis, Ascosphaera apis, Paenibacillus larvae y Melissococcus plutoniusHoney bees are subject to a wide variety of diseases and environmental threats. The main aim of this study was to detect those pathogens associated with honey bee losses in Spain, using the molecular techniques based on polymerase chain reaction (PCR). This national study was conducted during 2006 and 2007. The results show a high detection of Varroa destructor (Korean haplotype) y Nosema ceranae, a relevant prevalence of Acarapis woodi and low detection of Nosema apis, Ascosphaera apis, Paenibacillus larvae and Melissococcus plutonius

Colonisation patterns of Nosema ceranae in the Azores Archipelago

Nosema ceranae is a highly prevalent pathogen of Apis mellifera, which is distributed worldwide. However, there may still exist isolated areas that remain free of N. ceranae. Herein, we used molecular tools to survey the Azores to detect N. ceranae and unravel its colonisation patterns. To that end, we sampled 474 colonies from eight islands in 2014/2015 and 91 from four islands in 2020. The findings revealed that N. ceranae was not only present but also the dominant species in the Azores. In 2014/2015, N. apis was rare and N. ceranae prevalence varied between 2.7% in São Jorge and 50.7% in Pico. In 2020, N. ceranae prevalence increased significantly (p < 0.001) in Terceira and São Jorge also showing higher infection levels. The spatiotemporal patterns suggest that N. ceranae colonised the archipelago recently, and it rapidly spread across other islands, where at least two independent introductions might have occurred. Flores and Santa Maria have escaped the N. ceranae invasion, and it is remarkable that Santa Maria is also free of Varroa destructor, which makes it one of the last places in Europe where the honey bee remains naive to these two major biotic stressors.This research was funded by Portuguese funds through FCT (Fundação para a Ciência e a Tecnologia) in the framework of the project BeeHappy grant number POCI-01-0145-FEDER-029871. ARL was supported by a PhD scholarship (SFRH/BD/143627/2019) from the FCT. FCT provided financial support by national funds (FCT/MCTES) to CIMO (UIDB/00690/2020).info:eu-repo/semantics/publishedVersio

First data on the prevalence and distribution of pathogens in bumblebees (Bombus terrestris and Bombus pascuorum) from Spain

Bumblebees provide pollination services not only to wildflowers but also to economically important crops. In the context of the global decline of pollinators, there is an increasing interest in determining the pathogen diversity of bumblebee species. In this work, wild bumblebees of the species Bombus terrestris and Bombus pascuorum from northern and southern Spain were molecularly screened to detect and estimate prevalence of pathogens. One third of bumblebees were infected: while viruses only infected B. pascuorum, B. terrestris was infected by Apicystis bombi, Crithidia bombi and Nosema bombi. Ecological differences between host species might affect the success of the pathogens biological cycle and consequently infection prevalence. Furthermore, sex of the bumblebees (workers or males), sampling area (north or south) and altitude were important predictors of pathogen prevalence. Understanding how these factors affect pathogens distribution is essential for future conservation of bumblebee wild populations

Stable genetic diversity despite parasite and pathogen spread in honey bee colonies

In the last decades, the rapid spread of diseases, such as varroosis and nosemosis, associated with massive honey bee colonies mortality around the world has significantly decreased the number and size of honey bee populations and possibly their genetic diversity. Here, we compare the genetic diversity of Iberian honey bee colonies in two samplings performed in 2006 and 2010 in relation to the presence of the pathogenic agents Nosema apis, Nosema ceranae, and Varroa destructor in order to determine whether parasite and pathogen spread in honey bee colonies reflects changes in genetic diversity. We found that the genetic diversity remained similar, while the incidence of N. ceranae increased and the incidence of N. apis and V. destructor decreased slightly. These results indicate that the genetic diversity was not affected by the presence of these pathogenic agents in the analyzed period. However, the two groups of colonies with and without Nosema/Varroa detected showed significant genetic differentiation (G test). A detailed analysis of the allelic segregation of microsatellite loci in Nosema/Varroa-negative colonies and parasitized ones revealed two outlier loci related to genes involved in immune response.We thank beekeepers for providing the samples analyzed. This study was supported by INIA-FEDER grant numbers RTA2013-00042-C10-05 and 06 and RTA2008-00020-C02. The corresponding author of this paper is presently a member and receive support from COST Action FA1307 (Sustainable pollination in Europe: joint research on bees and other pollinators (SUPER-B). Irene Muñoz is supported by Fundación Séneca (Murcia, Spain) through the post-doctoral fellowship 19149/PD/13-N. We very much appreciated the helpful comments to improve the manuscript of two anonymous reviewers and the Editor Sven Thatje.info:eu-repo/semantics/publishedVersio

Diferencias morfométricas entre la abeja apis mellifera iberica y la abeja rusa de la región de primorsky

It has been proved that the Russian bees of the region of Primorsky have a great tolerance to Varroa. In the present work we have made a comparative study of these bees and Apis mellifera iberica, by means of a morphometric study, putting under the values obtained a descriptive statistical research, evaluating the normality of the distribution by means of the test of Kolmogorov-Smirnov and the differences between the two populations of bee by means of tests parametric (t´Student) or nonparametric (U of Mann-Whitney), according to the type of distribution

Frequent parasitism of Apis mellifera by trypanosomatids in geographically isolated areas with restricted beekeeping movements

Trypanosomatids form a group of high prevalence protozoa that parasitise honey bees, with Lotmaria passim as the predominant species worldwide. However, the knowledge about the ecology of trypanosomatids in isolated areas is limited. The Portuguese archipelagos of Madeira and Azores provide an interesting setting to investigate these parasites because of their geographic isolation, and because they harbour honey bee populations devoid of two major enemies: Varroa destructor and Nosema ceranae. Hence, a total of 661 honey bee colonies from Madeira and the Azores were analysed using different molecular techniques, through which we found a high prevalence of trypanosomatids despite the isolation of these islands. L. passim was the predominant species and, in most colonies, was the only one found, even on islands free of V. destructor and/or N. ceranae with severe restrictions on colony movements to prevent the spread of them. However, islands with V. destructor had a significantly higher prevalence of L. passim and, conversely, islands with N. ceranae had a significantly lower prevalence of the trypanosomatid. Crithidia bombi was detected in Madeira and on three islands of the Azores, almost always coincident with L. passim. By contrast, Crithidia mellificae was not detected in any sample. A High-Throughput Sequencing analysis distinguished two main haplotypes of L. passim, which accounted for 98% of the total sequence reads. This work suggests that L. passim and C. bombi are parasites that have been associated with honey bees predating the spread of V. destructor and N. ceranae.This work was funded by the Consejería de Educación, Cultura y Deportes, of the Junta de Castilla – La Mancha (European Regional development Fund) project No. SBPLY/19/180501/000334 and through the program COMPETE 2020—POCI (Programa Operacional para a Competividade e Internacionalização) and FCT (Fundação para a Ciência e a Tecnologia) in the framework of the project BeeHappy (POCI-01-0145-FEDER-029871).info:eu-repo/semantics/publishedVersio

Population Genetics of Nosema apis and Nosema ceranae: One Host (Apis mellifera) and Two Different Histories

Two microsporidians are known to infect honey bees: Nosema apis and Nosema ceranae. Whereas population genetics data for the latter have been released in the last few years, such information is still missing for N. apis. Here we analyze the patterns of nucleotide polymorphism at three single-copy loci (PTP2, PTP3 and RPB1) in a collection of Apis mellifera isolates from all over the world, naturally infected either with N. apis (N = 22) or N. ceranae (N = 23), to provide new insights into the genetic diversity, demography and evolution of N. apis, as well as to compare them with evidence from N. ceranae. Neutral variation in N. apis and N. ceranae is of the order of 1%. This amount of diversity suggests that there is no substantial differentiation between the genetic content of the two nuclei present in these parasites, and evidence for genetic recombination provides a putative mechanism for the flow of genetic information between chromosomes. The analysis of the frequency spectrum of neutral variants reveals a significant surplus of low frequency variants, particularly in N. ceranae, and suggests that the populations of the two pathogens are not in mutation-drift equilibrium and that they have experienced a population expansion. Most of the variation in both species occurs within honey bee colonies (between 62%-90% of the total genetic variance), although in N. apis there is evidence for differentiation between parasites isolated from distinct A. mellifera lineages (20%-34% of the total variance), specifically between those collected from lineages A and C (or M). This scenario is consistent with a long-term host-parasite relationship and contrasts with the lack of differentiation observed among host-lineages in N. ceranae (< 4% of the variance), which suggests that the spread of this emergent pathogen throughout the A. mellifera worldwide population is a recent event.This study was supported by funds from the Instituto Nacional de Investigación y Tecnología Agraria (INIA; http://www.inia.es/; grant numbers RTA2013-00042-C10-05 and 06), the Regional Government of Murcia (Fundación Séneca; http://fseneca.es/; grant number 19908/GERM/2015) and the Ministerio de Agricultura, Alimentación y Medio Ambiente (MAGRAMA; Plan Apícola Nacional 2014; http://www.magrama.gob.es). PDR is presently a member and receives support from COST Action FA1307, Sustainable pollination in Europe: joint research on bees and other pollinators, SUPER-B (http://www.cost.eu/COST_Actions/fa/Actions/FA1307)S

Survival of honey bees (Apis mellifera) infected with Crithidia mellificae spheroid forms (Langridge and McGhee: ATCC® 30254™) in the presence of Nosema ceranae

Crithidia mellificae, a trypanosomatid parasite of Apis mellifera, has been proposed to be one of the pathogens responsible for the serious honey bee colony losses produced worldwide in the last decade, either alone or in association with Nosema ceranae. Since this pathogenic effect contradicts the results of the experimental infections originally performed by Langridge and McGhee nearly 40 years ago, we investigated the potential linkage of this protozoan with colony decline under laboratory conditions. Nosema-free and trypanosomatid-free honey bees from three different colonies were experimentally infected with fresh C. mellificae spheroid forms (reference strain ATCC30254), with N. ceranae fresh spores and with both parasites at the same time. Replicate cages were kept at 27 °C and used to analyse survival. C. mellificae spheroid forms did not reduce significantly the survival of the worker bees (64.5% at 30 days post-infection vs. 77.8% for the uninfected bees used as controls; differences were non statistically significant) under these experimental conditions. In contrast, the cages infected with N. ceranae exhibited higher rates of mortality from the 20th day post-infection onwards, irrespective of the presence of C. mellificae, suggesting that the spheroid forms of the latter have no pathological effect on A. melliferaINIA-FEDER (RTA2013-00042-C10-06 and E-RTA2014-00003-C03)S