Epormenis cestri secretions in Sebastiania schottiana trees cause mass death of honey bee Apis mellifera larvae in Uruguay

For more than 60 years, sporadic cases of massive summer honey bee larvae mortality in colonies located near freshwater systems with abundant riparian vegetation have been reported in Uruguay. This odd phenomenon, known as “River disease” by beekeepers, can lead to colony death by depopulation. The aim of this study was to detect the causes of larvae death. Different experiments and analyses were performed using affected apiaries located between two important water courses. 1 day old larvae were the most susceptible and substances that killed the larvae were present in the nectar but not in the pollen. A palynological analysis of nectar samples showed that bees collect this resource from commonly pollinated floral species in the country. However, abundant fungi spores and conidia were found, which indicates that the bees also collected honeydews. In the riparian vegetation, bees were observed collecting the secretions of the planthopper Epormenis cestri on Sebastiania schottiana trees. It was found that the mortality period of larvae overlaps with the presence of E. cestri. Larvae maintained in the laboratory were fed (i) nectar from healthy colonies, (ii) nectar from affected colonies, and (iii) secretions of E. cestri. The mortality of the larvae that received nectar from colonies affected with River disease and secretions of E. cestri was higher than the mortality of those receiving nectar from healthy colonies. This represents the first report of planthopper honeydew causing mass larval mortality in honey bees

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

Sublethal effects of acaricides and Nosema ceranae infection on immune related gene expression in honeybees

Nosema ceranae is an obligate intracellular parasite and the etiologic agent of Nosemosis that affects honeybees. Beside the stress caused by this pathogen, honeybee colonies are exposed to pesticides under beekeeper intervention, such as acaricides to control Varroa mites. These compounds can accumulate at high concentrations in apicultural matrices. In this work, the effects of parasitosis/acaricide on genes involved in honeybee immunity and survival were evaluated. Nurse bees were infected with N. ceranae and/or were chronically treated with sublethal doses of coumaphos or tau-fluvalinate, the two most abundant pesticides recorded in productive hives. Our results demonstrate the following: (1) honeybee survival was not affected by any of the treatments; (2) parasite development was not altered by acaricide treatments; (3) coumaphos exposure decreased lysozyme expression; (4) N. ceranae reduced levels of vitellogenin transcripts independently of the presence of acaricides. However, combined effects among stressors on imagoes were not recorded. Sublethal doses of acaricides and their interaction with other ubiquitous parasites in colonies, extending the experimental time, are of particular interest in further research work.Fil: Garrido, Paula Melisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Cs. Exactas y Naturales. Centro de Investigación en Abejas Sociales; ArgentinaFil: Porrini, Martín Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Cs. Exactas y Naturales. Centro de Investigación en Abejas Sociales; ArgentinaFil: Antúnez, karina. Instituto de Investigaciones Biológicas "Clemente Estable"; UruguayFil: Branchiccela, Belén. Instituto de Investigaciones Biológicas "Clemente Estable"; UruguayFil: Martínez Noël, Giselle María Astrid. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones En Biodiversidad y Biotecnología; ArgentinaFil: Zunino, Pablo. Instituto de Investigaciones Biológicas "Clemente Estable"; UruguayFil: Salerno, Graciela Lidia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones En Biodiversidad y Biotecnología; ArgentinaFil: Eguaras, Martin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Cs. Exactas y Naturales. Centro de Investigación en Abejas Sociales; ArgentinaFil: Ieno, Elena. Highland Statistics; Españ

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

Una aproximación a la epidemiología de Nosema ceranae y su rol potencial en la despoblación de colonias de abejas Apis mellifera

Tribunal : Dra. Susana Castro, Dra. Claudia Piccini y Dr. Ciro Invernizzi

Nosema ceranae and RNA viruses in European and Africanized honeybee colonies (Apis mellifera) in Uruguay

International audienceNosema ceranae is one of the causative agents of Nosemosis, a severe disease that affects the honeybee Apis mellifera. The aim of the present work was to compare N. ceranae and RNA virus infections in Africanized bees (hybrid of Apis mellifera scutellata and A. m. mellifera) and European (Italian) bees (A. m. ligustica) under field conditions. Africanized and Italian healthy colonies were relocated to an Eucalyptus grandis plantation, a place where colonies inevitably acquire Nosemosis. Fifteen and 30 days after that, all colonies presented N. ceranae spores although Africanized bees were less infected than Italian bees. Sacbrood virus (SBV) and Black queen cell virus (BQCV) were detected in both races of bees, although Africanized bees presented a lower level of BQCV infection than Italian bees. At the end of the flowering period, Africanized colonies had a larger honeybee population and produced more honey than Italian colonies. These results suggest that Africanized bees may be able to limit N. ceranae and BQCV infections within the colony, and that this may allow them to be more productive