Resumo O objetivo deste trabalho foi identificar, por análise molecular, as espécies do gênero Helicoverpa nas lavouras – Bt e não Bt – de milho, soja e alfafa, no centro da Argentina. Um total de 1.343 lagartas foram analisadas por PCR-RFLP. A espécie H. zea foi a única detectada no milho não Bt e na maioria do Bt. A espécie H. gelotopoeon predominou na soja não Bt e na alfafa, mas H. zea ocorreu em baixa proporção. A soja Bt não apresentou infestações por Helicoverpa spp. A exótica H. armigera não foi encontrada, porém, mariposas adultas dessa espécie foram capturadas com armadilha luminosa em uma amostragem complementar.

Abstract The objective of this work was to identify, by molecular analysis, the species of the genus Helicoverpa in corn, soybean, and lucerne Bt and non-Bt crops, in central Argentina. A total of 1,343 carterpillars were analyzed by PCR-RFLP. Helicoverpa zea was the only species detected on non-Bt and on most Bt corn hybrids. The species H. gelotopoeon predominated on non-Bt soybean and on lucerne, and H. zea larvae occurred in low proportion. Bt soybean did not show Helicoverpa spp. infestations. The exotic H. armigera was not found, though adult moths of this species were light-trapped in a complementary sampling.

Abstract Microsporidia are obligate intracellular fungi with a remarkable ability to infect a wide range of invertebrate and vertebrate hosts. Namely, Enterocytozoon bieneusi is the most frequently microsporidia reported worldwide, and mainly associated with chronic diarrea and wasting syndrome in AIDS patients. Microscopy and PCR-based detection techniques are effective for diagnosis and identification of species and genotypes; however, these methods should be standardized in each laboratory. In this study, we performed microscopy and nested PCR techniques with PCR product sequencing to detect E. bieneusi in human stool samples. These techniques, if applied together, might prove useful for diagnosis and future epidemiological studies of intestinal microsporidiosis in Argentina.

Resumen Los microsporidios son hongos intracelulares obligados con una notable capacidad para infectar una amplia gama de hospedadores invertebrados y vertebrados. Enterocytozoon bieneusi es el microsporidio más frecuentemente reportado en todo el mundo, principalmente tricrómicaasociado con diarrea crónica y síndrome debilitante en pacientes con sida. Las técnicas dedetección basadas en microscopía y PCR son útiles para el diagnóstico y la identificación deespecies y genotipos, pero estos métodos deben estar estandarizados en cada laboratorio.En este estudio evaluamos técnicas de microscopía y PCR anidada, con secuenciación de losproductos, para detectar E. bieneusi en muestras de heces humanas. Estas técnicas, usadas con-juntamente, podrían ser útiles para su aplicación en el diagnóstico de microsporidiosis intestinaly para realizar estudios epidemiológicos de esta afección en Argentina.

Cohnella is a highly cellulolytic bacterial genus, which can be found in a variety of habitats. The aim of this study was to assess its presence in the digestive tract of termite species collected in North-eastern Argentina: Nasutitermes aquilinus, N. corniger and Cortaritermes fulviceps. Gut homogenates were incubated with cellulosic substrate for bacterial growth. Bacterial 16S rDNA was partially amplified using new primers for Cohnella spp. and cloned. Sequences obtained showed highest similarity (97.2-99.9%) with those of Cohnella spp. previously reported from diverse environments. Phylogenetic analysis tended to group the clones according to their host species and sampling sites. These results indicate the association of Cohnella-related intestinal symbionts with three common Neotropical termites. Their potential industrial application encourages further research.

Cohnella es un género de bacterias celulolíticas que puede ser encontrado en una variedad de hábitats. El propósito de este estudio fue registrar su presencia en el tracto digestivo de termitas (Nasutitermes aquilinus, N. corniger y Cortaritermes fulviceps) colectadas en el noreste argentino (NEA). Se incubaron homogenados de intestinos en sustrato celulósico para multiplicar las bacterias. Utilizando nuevos cebadores para Cohnella spp., se amplificó una porción del ADN ribosomal 16S bacteriano, el cual fue posteriormente clonado. Las secuencias obtenidas mostraron su mayor porcentaje de similitud (97,2-99,9%) con Cohnella spp., previamente reportadas en diversos ambientes. El análisis filogenético tendió a agrupar a los clones de acuerdo a la especie hospedante y al sitio de muestreo. Estos resultados indican que especies de termitas frecuentes en el NEA albergan simbiontes intestinales relacionados con el género Cohnella. Las potenciales aplicaciones industriales de estos microorganismos animan a profundizar los estudios.

Abstract Laboratory trials were performed to determine the impact of three Neotropical predatory coccinellids (Cycloneda sanguinea, Eriopis connexa and Coleomegilla quadrifasciata) and a minute pirate bug (Orius insidiosus) on Chaetosiphon fragaefolii, an important strawberry aphid pest. The predation on C. fragaefolii nymphs and adults, as well as the time to the first attack of all predators were compared with predation on Aphis gossypii. Predator preferences for prey and aphid defensive behavior were also evaluated. Moreover, the effect of coccinellids on C. fragaefolii population growth was assessed in experimental greenhouse conditions. The predation rate varied among predators, being significantly lower for O. insidiosus than for the coccinellids. Consumption was higher on A. gossypii than on C. fragaefolii, regardless of the aphids developmental stage. The time to the first attack of all predators was longer in the presence of C. fragaefolii. Walking away and cornicle secretion were the most common antipredator behaviors of aphid against coccinellids and O. insidiosus, respectively. Coccinellids preferred A. gossypii over C. fragaefolii, while O. insidiosus showed indifference. Cycloneda sanguinea and E. connexa exhibited the highest suppression effect on the growth rate of C. fragaefolii. Thus, the four predators evaluated could contribute to reduce strawberry aphid populations, especially C. sanguinea and E. connexa.

This is the first report of the association between the rose-grain aphid Metopolophium dirhodum, a potentially important cereal pest and the facultative symbiont Hamiltonella defensa. The infection with this gamma-proteobacterium was determined by PCR in laboratory-reared and field-collected specimens of an Argentinian population of the aphid. Partial bacterial 16S, IGS and 23S rRNA genes were sequenced and compared to other available Hamiltonella sequences by phylogenetic analysis. The present study provides new information on previously unknown M. dirhodum microbiota.

Esta es la primera comunicación sobre la asociación entre el áfido Metopolophium dirhodum, una plaga potencialmente importante de cereales, y el simbionte facultativo Hamiltonella defensa. La infección con esta gamma proteobacteria se determinó mediante PCR en ejemplares de una población argentina del áfido, tanto en individuos criados en laboratorio como en ejemplares colectados en campo. Se secuenció parte de los genes 16S y 23S del ARNr, y el espacio intergénico, y se realizó una comparación con otras secuencias disponibles de Hamiltonella a través de un análisis filogenético. Este estudio proporciona nueva información sobre la hasta ahora desconocida microbiota de M. dirhodum.

O objetivo deste trabalho foi estabelecer uma tabela de vida para os estágios imaturos de Epinotia aporema, como parte de um estudo mais amplo para seu controle biológico. Os insetos foram criados em dieta artificial a 25±1ºC e 16:8 (luz:escuridão) horas de fotoperíodo. Para a identificação dos estágios larvais para estudos de interação inseto-patógeno em condições de laboratório, as larguras de cápsula cefálica também foram determinadas. O período de incubação dos ovos foi de 4,13±0,30 dias, o estágio larval foi de 11,64±0,49 dias, e o tempo de desenvolvimento das pupas dependeu do sexo, com 8,51±0,69 dias para as fêmeas e 9,41±0,65 dias para os machos. Foram identificados cinco estágios larvais.

The objective of this work was to establish a life table for the immature stages of Epinotia aporema, as part of a wider investigation on its biological control. Insects were reared on an artificial diet at 25±1ºC and a 16:8 (light:dark) hour photoperiod. For the identification of larval instars for the study of pathogen-insect interactions under laboratory conditions, head capsule widths (HCWs) were also determined. The egg incubation period was 4.13±0.30 days, larval stage took 11.64±0.49 days, and the development time of the pupal phase was sex-dependent with 8.51±0.69 days for the females and 9.41±0.65 days for the males. Five larval instars were identified.

Plants of Viola cornuta displaying typical virus symptoms were observed during spring 2003 in a plant nursery in Córdoba, central Argentina. Electron microscopic examinations of symptomatic leaf samples revealed the presence of isometric virus-like particles about 30 nm in diameter. Subsequent serological analysis allowed the identification of the pathogen as a subgroup I strain of Cucumber mosaic virus (CMV). These results were confirmed by antigen capture - reverse transcription - polymerase chain reaction with specific CMV primers, and digestion with a restriction enzyme. This is the first report of CMV infecting V. cornuta in Argentina.

The ability of first and third-instar Delphacodes kuscheli Fennah (Hemiptera: Delphacidae) nymphs to acquire and transmit Mal de Río Cuarto virus (MRCV), under controlled conditions, was investigated. First and third-instar nymphs were allowed acquisition feeding separately on infected wheat plants for 48 hours. The insects were then placed in groups of three for serial transmissions to healthy wheat plants, using inoculation periods of 24 hours. Both instars of D. kuscheli were demonstrated to acquire and subsequently transmit the virus. Nevertheless, transmission trials showed highest transmission efficiency and shortest latent period when MRCV was acquired by first-instar nymphs.

Se comparó la capacidad de ninfas de primer y tercer estadío de Delphacodes kuscheli Fennah (Hemiptera: Delphacidae) para adquirir y posteriormente transmitir el Mal de Río Cuarto virus (MRCV), bajo condiciones controladas. Ninfas I y III avirulíferas se alimentaron separadamente de plantas de trigo infectadas durante 48 horas, para luego ser colocadas en subgrupos de tres individuos sobre plantas de trigo sanas. Se realizaron transmisiones seriales utilizando períodos de inoculación de 24 horas. Ambos estadií os lograron adquirir y transmitir el MRCV, pero se evidenció una mayor cantidad de subgrupos infectivos cuando la adquisición se efectuó como ninfas I, así como una disminución significativa en la duración del período de latencia del virus respecto de los insectos que adquirieron el MRCV durante el tercer estadio ninfal.

The Mal de Río Cuarto disease is caused by Mal de Río Cuarto virus (MRCV) transmitted by Delphacodes kuscheli. Comparative studies were carried out on the cytopathological alterations produced by MRCV in corn (Zea mays), wheat (Triticum aestivum) and barley (Hordeum vulgare), as seen with a transmission electron microscope. Corn plants were infected with viruliferous D. kuscheli collected from the endemic disease area (i.e. Río Cuarto County, Córdoba, Argentina). For the viral transmission to small grain cereal plants, laboratory rared insects were used. In this case, the inoculum source was wheat and barley plants infected with MRCV isolate grown in a greenhouse. Leaf samples with conspicuous symptoms were collected: enations and size reduction in corn; crenatures, swelling veins and dark green color in small grain cereals. Viral infection was corroborated by DAS-ELISA. Viroplasms containing complete and incomplete virus particles and fibrillar material were found in the cytoplasm of infected cells in all species. Mature virions were between 60 and 70 nm diameter. In wheat and barley, viroplasms and dispersed particles were observed only in phloem, while in corn virions were also found in cells of the bundle sheath. Crystalline arrays of particles were detected in corn enation constitutive cells. Tubular inclusions were found only in wheat samples. The three species showed abnormalities in the chloroplasts of affected cells. The results showed that MRCV cytopathology has similarities with other viruses from the genus Fijivirus, family family Reoviridae, but slight differences depending upon the host plant.

La enfermedad denominada mal de Río Cuarto es causada por el Mal de Río Cuarto virus (MRCV) transmitido por Delphacodes kuscheli. Se reportan los resultados de un estudio de las alteraciones citopatológicas producidas por el MRCV en maíz (Zea mays), trigo (Triticum aestivum) y cebada (Hordeum vulgare), observadas en microscopio electrónico de transmisión. Las plantas de maíz fueron inoculadas con ejemplares infectivos de D. kuscheli colectados en la zona endémica de la enfermedad. Para la transmisión del virus a los cereales de grano fino se utilizaron insectos criados en laboratorio, siendo la fuente de inóculo plantas de trigo y cebada infectadas con un aislamiento del virus obtenido en Río Cuarto y mantenido en invernáculo. Se colectaron muestras de hojas con síntomas conspicuos en maíz, y en cereales de grano fino. La infección viral fue corroborada mediante DAS-ELISA. Se encontraron viroplasmas, conteniendo partículas virales completas e incompletas y material fibrilar, en el citoplasma de las células infectadas en todas las especies. Los viriones maduros midieron entre 60 y 70 nm de diámetro. En trigo y cebada, los viroplasmas y partículas dispersas fueron observados sólo en el floema, mientras que en maíz también se encontraron viriones en las células de la vaina. En maíz, se detectaron partículas formando arreglos cristalinos en las células de las enaciones. Exclusivamente en las muestras de trigo, se encontraron inclusiones tubulares. Las tres especies mostraron anomalías en los cloroplastos de las células afectadas. Los resultados obtenidos ponen de manifiesto que la citopatología propia del MRCV presenta semejanzas con la de otros fijivirus y pequeñas diferencias dependiendo de la planta hospedante.

The disease caused by the "Mal de Rio Cuarto virus" (MRCV) is one of the most important diseases among those affecting maize (Zea mays) crops in Argentina. The MRCV belongs to the Reoviridae family, within the Fijivirus genus. It is spread in nature by Delphacodes kuscheli (Hemiptera: Delphacidae). The manner of transmission of the members of this virus genus is persistent propagative. An efficient virus transmission system was arranged in order to perform the various characterisation studies. These studies were carried out with healthy vector populations raised in the laboratory. Different acquisition, latency and inoculation periods were tested and a range of differential hosts was also evaluated, by breeding in phytotrons and controlled atmosphere chambers. A sufficient number of virus-free insects could thus be obtained to perform work. Experimental transmission of MRCV was successfully accomplished under identical conditions with acquisition, latency and inoculation periods of two, 10 and one days for fine grain cereals and two, 10 and two days for maize respectively. The following species were infected in this manner: maize (Zea mays), barley (Hordeum vulgare), oats (Avena sativa), wheat (Triticum aestivum), rye (Secale cereale), grama rhodes (Chloris gayana) and birdseed (Phalaris canariensis). Virus detection in inoculated plants was performed by means of serological tests, electrophoresis of the dsRNA in polyacrylamide gel (which showed the 10 typical bands of the fijiviruses) and electron microscopy, which showed 60 - 70 nm isometric particles.

Entre las enfermedades que afectan al cultivo de maíz (Zea mays) en Argentina, la producida por el virus del mal de Río Cuarto (MRCV) es la más importante. El MRCV pertenece a la familia Reoviridae, género Fijivirus, y su propagación en la naturaleza es realizada por Delphacodes kuscheli (Hemiptera: Delphacidae). La modalidad de transmisión para los miembros de este género de virus es persistente propagativa. Se estableció la necesidad de ajustar un sistema de transmisión eficiente del virus para estudios de caracterización, partiendo de poblaciones libres de virus criadas en laboratorio, para lo cual se ensayaron distintos períodos de adquisición, latencia e inoculación, evaluándose además un rango de hospedantes diferenciales. Se lograron obtener insectos libres de virus en cantidad suficiente para llevar a cabo los trabajos, mediante su cría en fitotrones y cámaras aclimatadas. La transmisión experimental del MRCV se efectuó exitosamente, bajo idénticas condiciones, empleando períodos de adquisición, latencia e inoculación de dos, 10 y uno día respectivamente para los cereales de grano fino y de dos, 10 y dos días para el maíz. Se infectaron de este modo las siguientes especies: maíz, cebada (Hordeum vulgare), avena (Avena sativa), trigo (Triticum aestivum), centeno (Secale cereale), grama rhodes (Chloris gayana) y alpiste (Phalaris canariensis). La detección del virus en las plantas inoculadas se efectuó mediante pruebas serológicas, análisis de dsRNA en electroforesis en gel de poliacrilamida (obteniéndose las 10 bandas típicas de los fijivirus) y microscopía electrónica, detectándose las partículas isométricas de entre 60 y 70 nm de diámetro.