Supplementation of honey bee production colonies with a native beneficial microbe mixture

Honey bee colonies form a complex superorganism, with individual and social immune defences that control overall colony health. Sometimes these defences are not enough to overcome infections by parasites and pathogens. For that reason, several studies have been conducted to evaluate different strategies to improve honey bee health. A novel alternative that is being studied is the use of beneficial microbes. In a previous study, we isolated and characterised bacterial strains from the native gut microbiota of honey bees. Four Apilactobacillus kunkeei strains were mixed and administered in laboratory models to evaluate their potential beneficial effect on larvae and adult bees. This beneficial microbe mixture was safe; it did not affect the expression of immune-related genes, and it was able to decrease the mortality caused by Paenibacillus larvae infection in larvae and reduced the Nosema ceranae spore number in infected adult honey bees. In the present study, we aimed to delve into the impact of the administration of this beneficial microbe mixture on honey bee colonies, under field conditions. The mixture was administered in sugar syrup using lyophilised bacterial cells or fresh cultures, by aspersion or sprayed and feeder, once a week for three consecutive weeks, in autumn or spring 2015, 2017 and 2019. Colony strength parameters were estimated before the administration, and one and three months later. Simultaneously different samples were collected to evaluate the infection levels of parasites and pathogens. The results showed that dministering the beneficial microbe mixture decreased or stabilised the infection by N. ceranae or Varroa destructor in some trials but not in others. However, it failed to improve the colony’s strength parameters or honey production. Therefore, field studies can be a game-changer when beneficial microbes for honey bees are tested, and meticulous studies should be performed to test their effectivenessAgencia Nacional de Investigación e InnovaciónInstituto Nacional de Investigación Agropecuari

Unraveling honey bee–varroa destructor interaction: multiple factors involved in differential resistance between two uruguayan populations

The ectoparasite Varroa destructor is the greatest biotic threat of honey bees Apis mellifera in vast regions of the world. Recently, the study of natural mite-resistant populations has gained much interest to understand the action of natural selection on the mechanisms that limit the mite population. In this study, the components of the A. mellifera–V. destructor relationship were thoroughly examined and compared in resistant and susceptible honey bee populations from two regions of Uruguay. Mite-resistant honey bees have greater behavioral resistance (hygienic and grooming behaviors) than susceptible honey bees. At the end of the summer, resistant honey bees had fewer mites and a lower deformed wing virus (DWV) viral load than susceptible honey bees. DWV variant A was the only detected variant in honey bees and mites. Molecular analysis by Short Tandem Repeat showed that resistant honey bees were Africanized (A. m. scutellata hybrids), whereas susceptible honey bees were closer to European subspecies. Furthermore, significant genetic differentiation was also found between the mite populations. The obtained results show that the natural resistance of honey bees to V. destructor in Uruguay depends on several factors and that the genetic variants of both organisms can play a relevant rol

Genetic diversification of an invasive honey bee ectoparasite across sympatric and allopatric host populations

Invasive parasites are major threats to biodiversity. The honey bee ectoparasite, Varroa destructor, has shifted host and spread almost globally several decades ago. This pest is generally considered to be the main global threat to Western honey bees, Apis mellifera, although the damages it causes are not equivalent in all its new host’s populations. Due to the high virulence of this parasite and the viruses it vectors, beekeepers generally rely on acaricide treatments to keep their colonies alive. However, some populations of A. mellifera can survive without anthropogenic mite control, through the expression of diverse resistance and tolerance traits. Such surviving colonies are currently found throughout the globe, with the biggest populations being found in Sub- Saharan Africa and Latin America. Recently, genetic differences between mite populations infesting surviving and treated A. mellifera colonies in Europe were found, suggesting that adaptations of honey bees drive mite evolution. Yet, the prevalence of such co-evolutionary adaptations in other invasive populations of V. destructor remain unknown. Using the previous data from Europe and novel genetic data from V. destructor populations in South America and Africa, we here investigated whether mites display signs of adaptations to different host populations of diverse origins and undergoing differing management. Our results show that, contrary to the differences previously documented in Europe, mites infesting treated and untreated honey bee populations in Africa and South America are genetically similar. However, strong levels of genetic differentiation were found when comparing mites across continents, suggesting ongoing allopatric speciation despite a recent spread from genetically homogenous lineages. This study provides novel insights into the co-evolution of V. destructor and A. mellifera, and confirms that these species are ideal to investigate coevolution in newly established host- parasite systems.Agencia Nacional de Investigación e InnovaciónPrograma ECOS-Su

Genetic diversification of an invasive honey bee ectoparasite across sympatric and allopatric host populations.

Invasive parasites are major threats to biodiversity. The honey bee ectoparasite, Varroa destructor, has shifted host and spread almost globally several decades ago. This pest is generally considered to be the main global threat to Western honey bees, Apis mellifera, although the damages it causes are not equivalent in all its new host's populations. Due to the high virulence of this parasite and the viruses it vectors, beekeepers generally rely on acaricide treatments to keep their colonies alive. However, some populations of A. mellifera can survive without anthropogenic mite control, through the expression of diverse resistance and tolerance traits. Such surviving colonies are currently found throughout the globe, with the biggest populations being found in Sub-Saharan Africa and Latin America. Recently, genetic differences between mite populations infesting surviving and treated A. mellifera colonies in Europe were found, suggesting that adaptations of honey bees drive mite evolution. Yet, the prevalence of such co-evolutionary adaptations in other invasive populations of V. destructor remain unknown. Using the previous data from Europe and novel genetic data from V. destructor populations in South America and Africa, we here investigated whether mites display signs of adaptations to different host populations of diverse origins and undergoing differing management. Our results show that, contrary to the differences previously documented in Europe, mites infesting treated and untreated honey bee populations in Africa and South America are genetically similar. However, strong levels of genetic differentiation were found when comparing mites across continents, suggesting ongoing allopatric speciation despite a recent spread from genetically homogenous lineages. This study provides novel insights into the co-evolution of V. destructor and A. mellifera, and confirms that these species are ideal to investigate coevolution in newly established host-parasite systems

Impact of nutritional stress on the honeybee colony health

Honeybees Apis mellifera are important pollinators of wild plants and commercial crops. For more than a decade, high percentages of honeybee colony losses have been reported worldwide. Nutritional stress due to habitat depletion, infection by different pests and pathogens and pesticide exposure has been proposed as the major causes. In this study we analyzed how nutritional stress affects colony strength and health. Two groups of colonies were set in a Eucalyptus grandis plantation at the beginning of the flowering period (autumn), replicating a natural scenario with a nutritionally poor food source. While both groups of colonies had access to the pollen available in this plantation, one was supplemented with a polyfloral pollen patty during the entire flowering period. In the short-term, colonies under nutritional stress (which consumed mainly E. grandis pollen) showed higher infection level with Nosema spp. and lower brood and adult bee population, compared to supplemented colonies. On the other hand, these supplemented colonies showed higher infection level with RNA viruses although infection levels were low compared to countries were viral infections have negative impacts. Nutritional stress also had long-term colony effects, because bee population did not recover in spring, as in supplemented colonies did. In conclusion, nutritional stress and Nosema spp. infection had a severe impact on colony strength with consequences in both short and long-term

Perfiles virales de colonias susceptibles y sobrevivientes a Varroa destructor

Varroa destructor es la principal amenaza biótica de Apis mellifera, es vector de diversos virus y es letal si las colonias no son tratadas a tiempo. En Uruguay existe una población de abejas que sobreviven naturalmente a la parasitación con este ácaro sin necesidad de tratamientos. Este fenómeno estaría asociado a un mayor comportamiento higiénico de esas abejas; pero, además, podría deberse a la presencia de comunidades virales diferenciales asociadas a las colonias. El objetivo de este trabajo fue cuantificar y caracterizar los virus presentes en colonias de A. mellifera sobrevivientes y susceptibles a V. destructor de nuestro país. Para ello se tomaron muestras de abejas nodrizas de estas colonias en primavera y en otoño, y se realizó la detección y cuantificación absoluta mediante qPCR de los virus: de la Parálisis Aguda (ABPV), de las Celdas Reales Negras (BQCV), de las Alas Deformes (DWV) y de la cría ensacada (SBV). Paralelamente, muestras de esas mismas colonias fueron sometidas a protocolos de enriquecimiento de las partículas virales y posterior secuenciación masiva (Illumina). Los resultados de este trabajo nos permitieron realizar la caracterización genómica de los principales virus de interés apícola (ABPV, BQCV, DWV y SBV). A su vez, se observó que en otoño las colonias sobrevivientes presentaron menor nivel de infección para algunos virus comparado con las colonias susceptibles. Por último, la secuenciación masiva permitió la detección de algunos fragmentos de virus que aún no se habían detectado en nuestro país, como el Virus del Lago Sinaí y el Virus Filamentoso de Apis mellifera. Continuamos estudiando los perfiles virales de las colonias sobrevivientes y susceptibles a V. destructor con el fin de avanzar hacia un control sustentable de las poblaciones de ácaros.Agencia Nacional de Investigación e Innovació

Sanitary situation of honey bees in Uruguay: novelties of the last decade

En los últimos años, la apicultura en Uruguay se enfrenta con bajos rendimientos de producción de miel y pérdidas anuales de colonias que pueden alcanzar el 30%, estando los problemas sanitarios involucrados en buena parte de esta situación. A nivel mundial la investigación sobre los factores que amenazan a las poblaciones de abejas melíferas se ha ampliado, abarcando los problemas nutricionales, la respuesta inmune, la microbiota intestinal, la identificación de nuevos patógenos o variantes de los mismos, el efecto de los agroquímicos, y otros insectos que comparten patógenos con las abejas melíferas. Respecto a la varroosis la investigación se ha enfocado en las poblaciones de abejas sobrevivientes a Varroa destructor. En Uruguay, la investigación sobre salud de las abejas melíferas en los últimos 10 años ha sido muy prolífica abordando buena parte de los temas mencionados desde las condiciones particulares que presenta el país. Esta revisión sobre la situación sanitaria de las abejas melíferas en Uruguay se centra en resultados de investigaciones nacionales sobre las parasitosis y virosis más prevalentes, la identificación de un nuevo parásito, el efecto de la nutrición y el herbicida glifosato tanto en la microbiota intestinal como en la sanidad, el estudio de parásitos y virus de las abejas melíferas presentes en abejorros nativos del género Bombus, y la descripción de una enfermedad específica del país como es el Mal del Río. Se resalta la importancia de los diferentes resultados para la apicultura nacional y se ponen en contexto con la información internacional reciente.In recent years, beekeeping industry in Uruguay faces low honey production yields and annual colony losses that can reach 30%, and health problems are involved in much of this situation. Worldwide, research on the factors that threaten honey bee populations has expanded, encompassing nutritional problems, the immune response, the intestinal microbiota, identification of new pathogens or its variants, the effect of agrochemicals, and other insects that share pathogens with honey bees. Regarding varroosis, research has focused on the populations of bees surviving Varroa destructor. In Uruguay, research on the health of honey bees in the last 10 years has been very prolific, addressing a good part of the aforementioned issues taking into account the particular conditions that the country presents. This review on the health situation of honey bees in Uruguay focuses on the results of national research on the most prevalent parasitosis and virosis, the identification of a new parasite, the effect of nutrition and the herbicide glyphosate on the intestinal microbiota and on the health, the study of parasites and viruses of honey bees present in native bumblebees of the genus Bombus, and the description of the country-specific disease (River disease). The importance of the diverse results for national beekeeping is highlighted and put in context with recent international information

Efecto de dosis subletales de pesticidas en la salud de las abejas melíferas

ANII: FCE_1_2017_1_13581

Intra-Colonial Viral Infections in Western Honey Bees (Apis Mellifera).

RNA viruses play a significant role in the current high losses of pollinators. Although many studies have focused on the epidemiology of western honey bee (Apis mellifera) viruses at the colony level, the dynamics of virus infection within colonies remains poorly explored. In this study, the two main variants of the ubiquitous honey bee virus DWV as well as three major honey bee viruses (SBV, ABPV and BQCV) were analyzed from Varroa-destructor-parasitized pupae. More precisely, RT-qPCR was used to quantify and compare virus genome copies across honey bee pupae at the individual and subfamily levels (i.e., patrilines, sharing the same mother queen but with different drones as fathers). Additionally, virus genome copies were compared in cells parasitized by reproducing and non-reproducing mite foundresses to assess the role of this vector. Only DWV was detected in the samples, and the two variants of this virus significantly differed when comparing the sampling period, colonies and patrilines. Moreover, DWV-A and DWV-B exhibited different infection patterns, reflecting contrasting dynamics. Altogether, these results provide new insight into honey bee diseases and stress the need for more studies about the mechanisms of intra-colonial disease variation in social insects