Wolbachia, a pandemic with potential

La infección causada por Wolbachia es la más extendida entre los animales. La capacidad de esta bacteria para manipular la reproducción de sus hospedadores la posicionan en el centro de la biología de los organismos, influyendo en procesos tan capitales como la determinación del sexo, el ciclo celular,la formación y extinción de especies y el comportamiento de artrópodos entre los que se cuentan varias plagas y vectores de enfermedades. Cualidades tales como la herencia vertical de Wolbachia, la velocidad a la que se propaga en las poblaciones que afecta, la capacidad de bloquear la actividad patogénica de diversos microorganismos o de acortar el ciclo de vida de sus hospedadores la señalan como un potencial instrumento para el control de poblaciones de insectos y nematodos perjudiciales. ¿Cuáles son las posibilidades que nos ofrece esta pandemia? En la presente contribución se presenta una revisión de los aspectos fundamentales de esta infección y sus implicancias prácticas para el manejo de insectos plaga. Esta revisión está basada en el simposio del mismo nombre acontecido en el VIII Congreso Argentino de Entomología.ABSTRACT. Wolbachia infection is the most widespread in animals. Its ability to manipulate insect reproduction places it at the center of organismal biology, af- fecting such important processes like sex determination, cell cycle, generation and extinction of species and behaviour of arthropods, including several pest and disease vector insects. Attributes like vertical transmission, the speed at which it drives in the population, the ability to block the pathogenic activity of several microorganisms and the ability to shorten the lifespan of its host point to this bac- terium as a potential tool to control harmful insects and nematodes. What are the possibilities offered by this pandemic? In the present work a detailed and updated review of the main aspects of this infection is presented, as well as the practical implications for managing pest and disease vector insects and nematodes. This review is based on the symposium of the same title held in the VIII Argentinean Meeting of Entomology.Fil: Rodriguero, Marcela Silvina. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Ecologia, Genetica y Evolución; Argentina; Consejo Nacional de Invest. Científ.y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Bs. As; Argentina

Mito-nuclear genetic comparison in a Wolbachia infected weevil: insights on reproductive mode, infection age and evolutionary forces shaping genetic variation

<p>Abstract</p> <p>Background</p> <p>Maternally inherited endosymbionts like <it>Wolbachia pipientis </it>are in linkage disequilibrium with the mtDNA of their hosts. Therefore, they can induce selective sweeps, decreasing genetic diversity over many generations. This sex ratio distorter, that is involved in the origin of parthenogenesis and other reproductive alterations, infects the parthenogenetic weevil <it>Naupactus cervinus</it>, a serious pest of ornamental and fruit plants.</p> <p>Results</p> <p>Molecular evolution analyses of mitochondrial (<it>COI</it>) and nuclear (<it>ITS1</it>) sequences from 309 individuals of <it>Naupactus cervinus </it>sampled over a broad range of its geographical distribution were carried out. Our results demonstrate lack of recombination in the nuclear fragment, non-random association between nuclear and mitochondrial genomes and the consequent coevolution of both genomes, being an indirect evidence of apomixis. This weevil is infected by a single <it>Wolbachia </it>strain, which could have caused a moderate bottleneck in the invaded population which survived the initial infection.</p> <p>Conclusions</p> <p>Clonal reproduction and <it>Wolbachia </it>infection induce the coevolution of bacterial, mitochondrial and nuclear genomes. The time elapsed since the <it>Wolbachia </it>invasion would have erased the traces of the demographic crash in the mtDNA, being the nuclear genome the only one that retained the signal of the bottleneck. The amount of genetic change accumulated in the mtDNA and the high prevalence of <it>Wolbachia </it>in all populations of <it>N. cervinus </it>agree with the hypothesis of an ancient infection. <it>Wolbachia </it>probably had great influence in shaping the genetic diversity of <it>N. cervinus</it>. However, it would have not caused the extinction of males, since sexual and asexual infected lineages coexisted until recent times.</p

Herramientas moleculares para la caracterización de Rhizoctonia spp. causales de patologías en tabaco Tipo Virginia en Salta y Jujuy (Argentina)

Desde fines de los años noventa la actividad tabacalera se encuentra afectada por una sintomatología que se visualiza con distintas manifestaciones externas como: marchitamiento de la parte aérea de la planta, amarillamiento y posterior necrosis de los tejidos que puede terminar con la muerte de la planta. Coincidente con aquella manifestación aérea, el sistema radicular se presenta con escaso desarrollo y en su mayoría con presencia de raíces con podredumbre, visualizándose muchas veces en el cuello necrosis total o parcial. En las campañas 2008/09/10 se relevaron 80 lotes comerciales de tabaco por campaña en las provincias de Salta y Jujuy, diagnosticándose Rhizoctonia solani agente causal de la podredumbre radicular, como la enfermedad con mayor prevalencia e incidencia, siendo este patógeno uno de los responsables del complejo del amarillamiento en tabaco. En sus comienzos esta sintomatología se manifestaba en forma aislada, pero en los últimos años se expandió por toda la zona tabacalera transformándose en uno de los problemas fitosanitarios más importantes de este sector productivo, por lo cual surge la necesidad de implementar medidas de manejo para mitigar esta dolencia. Uno de los pilares más importantes para el manejo de una enfermedad, es el diagnóstico certero del agente causal. El sistema de clasificación para los aislamientos de R. solani está basado en la capacidad de anastomosis o fusión de las hifas, siendo el criterio más usado para separarlo en grupos relativamente homogéneos. Se ha clasificado a este hongo en 14 grupos de anastomosis y varios subgrupos. En tabaco los grupos de anastomosis AG1, AG2.2, AG4 y AG5 causan damping off en plantines bajo almácigo y en plantas jóvenes posterior al transplante al campo y podredumbre radicular en planta adulta. Mientras que AG2.2 y AG3 producen la mancha foliar o target spot. Recientemente los marcadores moleculares y estudios de secuenciación de ADN demostraron ser herramientas de gran utilidad para la caracterización de aislamientos en AG permitiendo una caracterización más rápida y precisa que los tests de anastomosis convencionales ya que estos últimos pueden dar falsos positivos. Entre los métodos moleculares más utilizados para la clasificación de Rhizoctonia spp. se destaca el análisis de secuencias ITS o espaciadores internos transcritos (internal transcribed spacers). Los ITS son regiones de ADN no codificantes que separan las regiones que codifican las unidades de ADN ribosómico. Estas regiones muestran mayor polimorfismo de secuencia que las regiones codificantes y por lo tanto son útiles como fuente de marcadores genéticos y se utilizaron para estudios filogenético en Rhizoctonia spp. En el presente trabajo se caracterizaron 49 aislamientos de Rhizoctonia spp. colectados en diferentes lotes comerciales de tabaco en las provincias de Salta y Jujuy empleando marcadores ITS-rDNA.Fil: Mercado Cárdenas, Guadalupe. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Salta-Jujuy. Estación Experimental Agropecuaria Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Galván, Marta Zulema. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Salta-Jujuy. Estación Experimental Agropecuaria Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Rodriguero, Marcela Silvina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentin

Geographical Range and Laboratory Studies on Apanteles opuntiarum (Hymenoptera: Braconidae) in Argentina, a Candidate for Biological Control of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America

La polilla de la tuna, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), es una plaga que amenaza las Opuntia spp. nativas de América del Norte. Se han implementado varias estrategias para su control, erradicándola de México pero no de los Estados Unidos, donde ha continuado incrementando su distribución geográfica con éxito. Por lo tanto, se propone un enfoque integrado que incluya al control biológico para regular las poblaciones de C. cactorum en América del Norte. Se realizaron relevamientos de campo del parasitoide recientemente descrito, Apanteles opuntiarum Martínez & Berta, dentro del área de distribución nativa de C. cactorum en Argentina, y se realizaron estudios de laboratorio para desarrollar un protocolo de cría del parasitoide. Apanteles opuntiarum fue el parasitoide más común de C. cactorum y sus distribuciones en el campo coincidieron ampliamente. En el laboratorio, el éxito reproductivo del parasitoide se maximizó cuando una o dos avispas estuvieron expuestas a 30 larvas dentro de un recipiente de 500 ml. Hembras criadas en laboratorio fueron menos exitosas parasitando hospedadores que hembras provenientes del campo. A pesar del éxito logrado en la cría de los parasitoides, obtuvimos una proporción de sexos sesgada hacia machos en los experimentos. Como este sesgo podría estar relacionado a la presencia del parásito reproductivo Wolbachia, tanto la colonia de laboratorio como individuos provenientes del campo fueron analizados y poseían Wolbachia. El presente estudio proporcionó información útil de campo y laboratorio para (1) estandarizar una técnica de cría en laboratorio; (2) realizar estudios de especificidad de hospedadores en condiciones de cuarentena; y (3) seleccionar las poblaciones de parasitoides que mejor coinciden con el clima de las áreas invadidas por C. cactorum en América del Norte.The cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), is a pest that threatens native Opuntia spp. in North America. Control tactics developed and implemented against this invasive pest successfully eradicated the moth in Mexico and on barrier islands in the United States. However, with the cancellation of the regional management program in the United States, no control tactics are being implemented to mitigate the expansion of the moth's geographical range. Hence, an integrated approach including biological control is proposed to regulate the population of C. cactorum in North America. Field surveys of the recently described parasitoid, Apanteles opuntiarum Martínez & Berta, were carried out within the C. cactorum native range in Argentina, and laboratory studies were conducted to develop a parasitoid rearing protocol. Apanteles opuntiarum was the most common parasitoid of C. cactorum and their field distributions were similar. In the laboratory, the parasitoid's reproductive success was maximized when one or two female wasps were exposed to 30 host larvae within a 500 ml container. Laboratory reared females were less successful at parasitizing hosts than field collected females. In spite of the success achieved with laboratory rearing, male bias was observed throughout the experiments. Because this bias might be related to the presence of the reproductive parasite Wolbachia, both laboratory colony and field collected individuals were screened and Wolbachia was detected. This study provides useful field and laboratory information on (1) laboratory rearing techniques for A. opuntiarum; (2) developing host specificity test protocols for studies under quarantine conditions; and (3) selecting parasitoid populations that best match the climatic conditions present in the C. cactorum invaded areas of North America.Fil: Mengoni Goñalons, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Varone, Laura. Fundación para el Estudio de Especies Invasivas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Logarzo, Guillermo Alejandro. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Guala, Mariel. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Rodriguero, Marcela Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Hight, Stephen D.. United States Department Of Agriculture. Agriculture Research Service; Estados UnidosFil: Carpenter, James E.. United States Department Of Agriculture. Agriculture Research Service; Estados Unido

The Effect of Reproductive System on Invasiveness: Lessons from South American Weevils

Successful invasion of a species into novel, marginal areas often requires the ability to face different ecological characteristics than those prevailing in its native environment. In insects, one of the factors that affect invasiveness is the reproductive system. Unisexuality provides advantages because a single specimen can initiate a new population. Unisexual reproduction precludes breakup of genetic combinations that promote ecological specialization, although it may limit evolutionary potential for colonization. In order to assess the importance of the reproductive mode in the colonization ability of the weevils that are native to South America, we compared 1 bisexual and 2 parthenogenetic species that expanded their ranges in the last 2 centuries. First, for parthenogenetic species we tested clonality of the sample. Second, we proposed central and marginal areas through phylogeographic and habitat modeling analyses, and identified the pathways of dispersal for each species. Bisexual Naupactus xanthographus (Germar) (Coleoptera: Curculionidae) expanded its range westward to areas with similar environmental constraints than in its native ecosystem. Conversely, parthenogenetic Naupactus leucoloma Boheman and Naupactus cervinus Boheman (both Coleoptera: Curculionidae) invaded other continents where they had low to null predicted habitat suitability. While a single clone of N. cervinus successfully established around the world in areas with apparently adverse conditions, clones of N. leucoloma expanded their range to areas only moderately suitable. We conclude that parthenogenesis is a driver in these particular species for colonization of marginal habitats. However, N. cervinus also would have pre-existing adaptations that allowed it to establish in areas with apparently low potential to survive.Fil: Rodriguero, Marcela Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Guzman, Noelia Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Lanteri, Analia Alicia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Confalonieri, Viviana Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Grupo de Investigación en Filogeografía y Filogenias Moleculares; Argentin

Characterization of small-spored Alternaria from Argentinean crops through a polyphasic approach

Small-spored Alternaria have been isolated from a wide variety of food crops, causing both economic losses and human health risk due to the metabolites produced. Their taxonomy has been discussed widely, but no scientific consensus has been established in this field to date. Argentina is a major exporter of agricultural products, so it is essential to thoroughly understand the physiological behaviour of this pathogen in a food safety context. Thus, the objective of this work was to characterize small-spored Alternaria spp. obtained from tomato fruits, pepper fruits, wheat grains and blueberries from Argentina by a polyphasic approach involving metabolomic and phylogenetic analyses based on molecular and morphological characters. Morphological analysis divided the population studied into three groups; A. arborescens sp.-grp., A. tenuissima sp.-grp., and A. alternata sp.-grp. However, when these characters were simultaneously analysed with molecular data, no clearly separated groups were obtained. Haplotype network and phylogenetic analysis (both Bayesian and maximum parsimony) of a conserved region yielded the same result, suggesting that all isolates belong to the same species. Furthermore, no correlation could be established between morphological species-groups and a metabolite or group of metabolites synthesized. Thus, the whole set of analyses carried out in the present work supports the hypothesis that these small-spored Alternaria isolates from food belong to the same species. Identification at species level through classical morphology or modern molecular techniques does not seem to be a useful tool to predict toxicological risk in food matrices. The detection of any small-spored Alternaria from Section Alternaria (D.P. Lawr., Gannibal, Peever & B.M. Pryor 2013) in food implies a potential toxicological risk.Fil: Da Cruz Cabral, Lucía Mariana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Rodriguero, Marcela Silvina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Stenglein, Sebastian Alberto. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Nielsen, Kristian Fog. Technical University of Denmark; DinamarcaFil: Patriarca, Andrea Rosana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; Argentin

A tale of swinger insects: Signatures of past sexuality between divergent lineages of a parthenogenetic weevil revealed by ribosomal intraindividual variation

Naupactus cervinus (Boheman) (Curculionidae, Naupactini) is a parthenogenetic weevil native to the Paranaense Forest which displays high levels of genetic variation. Two divergent clades were identified, one ranging in forest areas (Forest clade), and the other in open vegetation areas (Grassland clade). Both of them have individuals with high levels of heterozygosity in ribosomal sequences. Investigation of intraindividual variation in ITS1 sequences through cloning and posterior sequencing suggested that mating between both groups most likely occurred in the Paranaense Forest after a secondary contact, which led to fixed heterozygotes as a consequence of parthenogenesis. Otherwise, sexual segregation would have disrupted multilocus genotypes. Only a small number of heterozygous genotypes of all the possible combinations are found in nature. We propose the occurrence of a hybrid zone in the Paranaense Forest. The fact that it is one of the most important biodiversity hotspots of the world, together with its key role for investigating evolutionary processes, makes it worthy of conservation. This is the first genetic evidence of bisexuality in N. cervinus.Fil: Rodriguero, Marcela Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Wirth, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Alberghina, Josefina Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Lanteri, Analía Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; ArgentinaFil: Confalonieri, Viviana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin

Mito-nuclear genetic comparison in a Wolbachia infected weevil: Insights on reproductive mode, infection age and evolutionary forces shaping genetic variation

Background: Maternally inherited endosymbionts like Wolbachia pipientis are in linkage disequilibrium with the mtDNA of their hosts. Therefore, they can induce selective sweeps, decreasing genetic diversity over many generations. This sex ratio distorter, that is involved in the origin of parthenogenesis and other reproductive alterations, infects the parthenogenetic weevil Naupactus cervinus, a serious pest of ornamental and fruit plants. Results: Molecular evolution analyses of mitochondrial (COI) and nuclear (ITS1) sequences from 309 individuals of Naupactus cervinus sampled over a broad range of its geographical distribution were carried out. Our results demonstrate lack of recombination in the nuclear fragment, non-random association between nuclear and mitochondrial genomes and the consequent coevolution of both genomes, being an indirect evidence of apomixis. This weevil is infected by a single Wolbachia strain, which could have caused a moderate bottleneck in the invaded population which survived the initial infection. Conclusions: Clonal reproduction and Wolbachia infection induce the coevolution of bacterial, mitochondrial and nuclear genomes. The time elapsed since the Wolbachia invasion would have erased the traces of the demographic crash in the mtDNA, being the nuclear genome the only one that retained the signal of the bottleneck. The amount of genetic change accumulated in the mtDNA and the high prevalence of Wolbachia in all populations of N. cervinus agree with the hypothesis of an ancient infection. Wolbachia probably had great influence in shaping the genetic diversity of N. cervinus. However, it would have not caused the extinction of males, since sexual and asexual infected lineages coexisted until recent times.Facultad de Ciencias Naturales y Muse

Molecular and Morphological Phylogenetic Analysis of Naupactus Dejean (Curculionidae: Entiminae) and Allied Genera: The Dilemma of Classification

Naupactus (Curculionidae: Entiminae) is the most speciose weevil genus of the tribe Naupactini. The main objective of this work is to recognize species groups within Naupactus and to analyze the relationships between this and other Neotropical genera. For this purpose, we compiled a combined data matrix of 60 terminal units corresponding to 40 species for which we recorded 812 molecular and morphological characters (763 and 49 respectively), which were analyzed by Maximum Parsimony and Bayesian analyses. The single tree obtained from each analysis was rooted with Cyrtomon inhalatus. The species of Naupactus were recovered as different monophyletic groups, some of them closer to other genera of Naupactini (Lanterius, Teratopactus, Pantomorus and Parapantomorus) than to species of the same genus. We conclude that Naupactus is non-monophyletic, even though most species can be recognized based on a particular combination of morphological characters, which are probably symplesiomorphic. To be consistent with the cladistic principles, some genera diversified in marginal areas of the Pantomorus-Naupactus complex should be synonymized with Naupactus; however, these nomenclatural changes may not ensure a generic definition based on synapomorphies. We prefer to be conservative about the current classification until more evidence is available. The only nomenclatural amendments proposed herein are the transference of Naupactus inermis Hustache to Lanterius and of N. setarius to Symmathetes.Facultad de Ciencias Naturales y Muse

Biological characterization of Aedes albopictus (Diptera: Culicidae) in Argentina: Implications for arbovirus transmission

Aedes albopictus (Diptera: Culicidae) is an invasive mosquito, native to Asia, that has expanded its range worldwide. It is considered to be a public health threat as it is a competent vector of viruses of medical importance, including dengue, chikungunya, and Zika. Despite its medical importance there is almost no information on biologically important traits of Ae. albopictus in Argentina. We studied life cycle traits, demographic parameters and analyzed the competence of this mosquito as a virus vector. In addition, we determined the prevalence of Wolbachia strains in Ae. albopictus as a first approach to investigate the potential role of this bacteria in modulating vector competence for arboviruses. We observed low hatch rates of eggs, which led to a negative growth rate. We found that Ae. albopictus individuals were infected with Wolbachia in the F1 but while standard superinfection with wAlbA and wAlbB types was found in 66.7% of the females, 16.7% of the females and 62.5% of the males were single-infected with the wAlbB strain. Finally, despite high levels of infection and dissemination, particularly for chikungunya virus, Ae. albopictus from subtropical Argentina were found to be relatively inefficient vectors for transmission of both chikungunya and dengue viruses.Centro de Estudios Parasitológicos y de Vectore