Effectiveness of several nutritional sources on the virulence of <i>Beauveria bassiana</i> s.l. CEP147 against the planthopper <i>Delphacodes kuscheli</i>

Delphacodes kuscheli Fennah (Hemiptera: Delphacidae) is the main planthopper vector of Mal de R ıo Cuarto virus (MRCV), a Fijivirus that severely affects maize production in Argentina. The effect of several nutritional sources on the virulence of Beauveria bassiana s.l. CEP147 (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) against this planthopper was evaluated with the aim to select some of them to be incorporated in future mass production studies. Ten agar-agar 2% media were used. Media were supplemented with 10 g of sucrose and 4% flour of either amaranth, chia, flax, oat bran, parboiled rice, poppy, quinoa, or wheat germ. Sabouraud dextrose agar with 1% yeast extract (SDAY) was used as control, and sucrose agar medium supplemented with 2% chitin was used as a possible inductor of enzymatic activity. We evaluated the effect of each medium on colony growth, conidial yield, viability, size, adherence, hydrophobicity, protease activity, cumulative mortality, and median survival time (MST). Principal component analysis indicated that conidial viability and adherence explained the most of the total variance, indicating that these variables can be used as indicators of fungal virulence. Medium supplemented with chia flour not only increased conidial viability (100%) and adherence (0.09 A550) with respect to the control medium, but also produced high D. kuscheli mortality (91.7%), with the lowest MST (5.2 days).We suggest that chia flour, which is rich in carbohydrates, proteins, vitamins, andminerals, might be incorporated as a nutritional supplement to solid substrates in order to increase the virulence of B. bassiana s.l. CEP147 against this and other pests. However, future studies are necessary to evaluate the effectiveness of this nutritional source on solid-state fermentation.Puede accederse a los datos utilizados para este artículo haciendo clic en "Documentos relacionados".Centro de Investigaciones en FitopatologíaFacultad de Ciencias Naturales y Muse

Oviposición de <i>Delphacodes kuscheli</i> (Homoptera-Delphacidae) sobre plantas de cebada en condiciones de laboratorio

Delphacodes kuscheli Fennah es, al presente, el &uacute;nico vector demostrado del Mal de R&iacute;o Cuarto del ma&iacute;z en la Argentina, principal enfermedad vir&oacute;sica que actualmente afecta a este cultivo. El insecto se desarrolla sobre distintas gram&iacute;neas, siendo la cebada uno de sus hospedantes m&aacute;s utilizados en condiciones de laboratorio. En la presente contribuci&oacute;n se analiza la preferencia por sitios de oviposici&oacute;n, su ubicaci&oacute;n en los tejidos vegetales y se brindan las caracter&iacute;sticas generales de las posturas. Se registr&oacute; el n&uacute;mero de huevos en tallo, vaina foliar, l&iacute;gula y l&aacute;mina foliar (tercios inferior, medio y superior). La vaina foliar y el tercio inferior de la l&aacute;mina fueron los sitios preferidos por el vector para la oviposici&oacute;n (F=18.6; gl 3/92; p&lt; 0,001, localiz&aacute;ndose con mayor frecuencia hasta 1 cm por arriba de la l&iacute;gula y hasta 1,5 cm por debajo de &eacute;sta. El 91,44% de las posturas se encontr&oacute; relacionado a la vena media mientras que s&oacute;lo el 8,55% lo estaba con venas secundarias. La hoja 4 fue la que conten&iacute;a el mayor n&uacute;mero de huevos, siendo tambi&eacute;n la m&aacute;s utilizada . El n&uacute;mero m&aacute;s frecuente de huevos por incisi&oacute;n fue dos. Los huevos depositados en la vaina foliar se ubicaron en cavidades aer&iacute;feras del par&eacute;nquima o en este tejido, cuando los espacios no estaban presentes. Los depositados en las l&aacute;minas foliares se localizaron en el mes&oacute;filo, generalmente en relaci&oacute;n con la vena media. Las caracter&iacute;sticas de las posturas coincidieron con las descriptas para otros delf&aacute;cidos.Delphacodes kuscheli Fennah is at present the only species with demostrated ability as a vector of Mal de R&iacute;o Cuarto del ma&iacute;z in Argentina, the main virus disease nowadays affecting this crop. This insect develops on different gramineae. Under laboratory conditions, the barley is one of its preferred hosts. The main subject of this paper was to study the site preferences for oviposition. Egg characteristics and their localization in the plant tissues were also analyzed. The number of eggs in stem, leaf sheath, ligulae and leaf blade (lower, medium and upper third) were recorded. Leaf sheath and basal portion of leaf blade were significantly preferred for oviposition (ANOVA: F=18,6; gl 3/92; p&lt; 0,001); the eggs being placed most frequently at 1cm over the ligule and 1,5 cm below it. They were attached predominantly to the midle vein (91,44%) and occasionally (8,55%) to secondary veins. The more exploited leaf for oviposition was the number four, on which the greatest number of eggs was also recorded. The more frequent egg number by incision was two. In the leaf sheaths, they were located inside air spaces, or in the parenchymatic tissue, if they were absent. In the leaf blades, eggs were placed in the mesophyll, usually beside mid-vein. Egg features resemble those of other delphacids

Descriptions of immatures of the South American plant hopper, Taosa (C.) longula

Descriptions of the immature stages of Taosa (Cuernavaca) longula Remes Lenicov (Hemiptera: Fulgoroidea: Dictyopharidae) and a key for their identification is provided for specimens collected on the water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Commelinales: Pontederiaceae), in northeastern Argentina and Peru. Newly emerged nymphs from eggs collected in the field were reared in rearing chambers, and each stage was fixed to microscopic examination and illustration. Fifth nymphal instars can be easily recognized from congeners by the brown marked pattern coloration, shorter vertex, and the distinguishable median carina along the frons. Information on behavior and developmental time is also included.Facultad de Ciencias Naturales y Muse

Descriptions of immatures of the South American plant hopper, Taosa (C.) longula

Descriptions of the immature stages of Taosa (Cuernavaca) longula Remes Lenicov (Hemiptera: Fulgoroidea: Dictyopharidae) and a key for their identification is provided for specimens collected on the water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Commelinales: Pontederiaceae), in northeastern Argentina and Peru. Newly emerged nymphs from eggs collected in the field were reared in rearing chambers, and each stage was fixed to microscopic examination and illustration. Fifth nymphal instars can be easily recognized from congeners by the brown marked pattern coloration, shorter vertex, and the distinguishable median carina along the frons. Information on behavior and developmental time is also included.Facultad de Ciencias Naturales y Muse

New taxa and combinations in Neotropical Delphacini (Hemiptera: Fulgoroidea)

A new South American genus of Delphacini (Hemiptera: Fulgoromorpha: Delphacidae), Neodelphax n. gen., is described. It includes a new species, N. sakakibarai sp. n., which is described herein, and two species that are removed from the genus Dicranotropis. All of them are illustrated. Supplementary descriptions of female N. fuscoterminata (Berg) comb. n. and N. acheron (Fennah) comb. n., including some new records and host plant associations are added. A preliminary key for males and females of South American species of Neodelphax with representative illustrations is also provided.Facultad de Ciencias Naturales y Museo (FCNM

Descriptions of immatures of the South American plant hopper, Taosa (C.) longula

Descriptions of the immature stages of Taosa (Cuernavaca) longula Remes Lenicov (Hemiptera: Fulgoroidea: Dictyopharidae) and a key for their identification is provided for specimens collected on the water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Commelinales: Pontederiaceae), in northeastern Argentina and Peru. Newly emerged nymphs from eggs collected in the field were reared in rearing chambers, and each stage was fixed to microscopic examination and illustration. Fifth nymphal instars can be easily recognized from congeners by the brown marked pattern coloration, shorter vertex, and the distinguishable median carina along the frons. Information on behavior and developmental time is also included.Fil: Marino, Ana Maria. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hernández, María Cristina. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Brentassi, Maria Eugenia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Defea, Bárbara Soledad. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Localización y caracterización morfológica de endosimbiontes obligados de Delphacodes Kuscheli y Dalbulus Maidis, dos especies de chicharritas vectoras de enfermedades del cultivo de maíz en Argentina (hemiptera: auchenorrhyncha)

Delphacodes kuscheli y Dalbulus maidis son dos especies de hemípteros auquenorrincos de importancia fitosanitaria que transmiten el “Mal de Río Cuarto virus” y el “Corn Stunt Spiroplasma” respectivamente, enfermedades que afectan al cultivo de maíz en Argentina. Entre los hemípteros es conocida la presencia de endosimbiontes obligados (bacterias u hongos) que proveen de aminoácidos esenciales y vitaminas indispensables para completar su ciclo vital. El objetivo de este trabajo es dar a conocer la localización y caracterización morfológica de los endosimbiontes obligados asociados a ambas especies. Los insectos provinieron de crías mantenidas en el Bioterio de la División Entomología, Facultad de Ciencias Naturales y Museo de La Plata. Las observaciones se realizaron con microscopio óptico y electrónico de transmisión para lo cual hembras adultas se procesaron según técnicas convencionales de fijación, inclusión y coloración. D. kuscheli aloja organismos eucariotas, yeast-like symbionts (YLS) en el cuerpo graso abdominal y en el polo posterior de los ovocitos; a nivel ultraestructural se destaca el grosor de la pared celular. Los endosimbiontes de D. maidis se alojan en órganos pares abdominales (bacteriomas) formados por células uninucleadas y una zona sincitial donde se localizan bacterias de forma irregular de gran tamaño (8-12 µm de longitud). Palabras clave: endosimbiontes, maíz, Delphacodes kuscheli, Dalbulus maidis, Argentina.Delphacodes kuscheli and Dalbulus maidis are two species of hemipterans auchenorrhynchans of phytosanitary importance that transmit the “Mal de Río Cuarto virus” and the “Corn Stunt Spiroplasma” respectively, diseases which affects maize crop in Argentina. Among hemipterans the presence of obligate endosymbionts (bacterial and/or fungal) that providing of essential amino acids and vitamins necessary for the life cycle of the host is known. The aim of this work is to provide the localization and morphological characterization of the obligate endosymbionts related with both species. The insects were reared in the Bioterio of the División Entomología, Facultad de Ciencias Naturales y Museo de La Plata. The observations were made using light and transmission electron microscopy. Adult females were processed using conventional methods of fixation, inclusion and coloration. D. kuscheli harbors eukaryotic organisms, yeast-like symbionts (YLS) in the abdominal fat body and in the posterior pole of the oocytes; at ultrastructural level the main character is the thickness of the cell wall. Endosymbionts of D. maidis are harbored in paired abdominal organs (bacteriomes) formed by uninucleate cells and a syncytial zone where irregular and big bacterium (8-12 µm long) are localized. Keywords: endosymbionts, corn, Delphacodes kuscheli, Dalbulus maidis, Argentina

Localización y caracterización morfológica de endosimbiontes obligados de Delphacodes kuscheli y Dalbulus maidis, dos especies de chicharritas vectoras de enfermedades del cultivo de maíz en Argentina (Hemiptera: Auchenorrhyncha)

Delphacodes kuscheli y Dalbulus maidis son dos especies de hem&iacute;pteros auquenorrincos de importancia fitosanitaria que transmiten el &ldquo;Mal de R&iacute;o Cuarto virus&rdquo; y el &ldquo;Corn Stunt Spiroplasma&rdquo; respectivamente, enfermedades que afectan al cultivo de ma&iacute;z en Argentina. Entre los hem&iacute;pteros es conocida la presencia de endosimbiontes obligados (bacterias u hongos) que proveen de amino&aacute;cidos esenciales y vitaminas indispensables para completar su ciclo vital. El objetivo de este trabajo es dar a conocer la localizaci&oacute;n y caracterizaci&oacute;n morfol&oacute;gica de los endosimbiontes obligados asociados a ambas especies. Los insectos provinieron de cr&iacute;as mantenidas en el Bioterio de la Divisi&oacute;n Entomolog&iacute;a, Facultad de Ciencias Naturales y Museo de La Plata. Las observaciones se realizaron con microscopio &oacute;ptico y electr&oacute;nico de transmisi&oacute;n para lo cual hembras adultas se procesaron seg&uacute;n t&eacute;cnicas convencionales de fijaci&oacute;n, inclusi&oacute;n y coloraci&oacute;n. D. kuscheli aloja organismos eucariotas, yeast-like symbionts (YLS) en el cuerpo graso abdominal y en el polo posterior de los ovocitos; a nivel ultraestructural se destaca el grosor de la pared celular. Los endosimbiontes deD. maidis se alojan en &oacute;rganos pares abdominales (bacteriomas) formados por c&eacute;lulas uninucleadas y una zona sincitial donde se localizan bacterias de forma irregular de gran tama&ntilde;o (8-12 &mu;m de longitud).Delphacodes kuscheli and Dalbulus maidis are two species of hemipterans auchenorrhynchans of phytosanitary importance that transmit the &ldquo;Mal de R&iacute;o Cuarto virus&rdquo; and the &ldquo;Corn Stunt Spiroplasma&rdquo; respectively, diseases which affects maize crop in Argentina. Among hemipterans the presence of obligate endosymbionts (bacterial and/or fungal) that providing of essential amino acids and vitamins necessary for the life cycle of the host is known. The aim of this work is to provide the localization and morphological characterization of the obligate endosymbionts related with both species. The insects were reared in the Bioterio of the Divisi&oacute;n Entomolog&iacute;a, Facultad de Ciencias Naturales y Museo de La Plata. The observations were made using light and transmission electron microscopy. Adult females were processed using conventional methods of fixation, inclusion and coloration. D. kuscheli harbors eukaryotic organisms, yeast-like symbionts (YLS) in the abdominal fat body and in the posterior pole of the oocytes; at ultrastructural level the main character is the thickness of the cell wall. Endosymbionts of D. maidis are harbored in paired abdominal organs (bacteriomes) formed by uninucleate cells and a syncytial zone where irregular and big bacterium (8-12 &mu;m long) are localized

Modeling population dynamics of yeast-like symbionts (Ascomycota: Pyrenomycetes: Clavicipitaceae) of the planthopper Delphacodes kuscheli (Hemiptera: Delphacidae)

Fil: Liljesthröm, Gerardo G.. Centro de Estudios en Parasitología y Vectores (CEPAVE). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Brentassi, María Eugenia. División Entomología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Marino de Remes Lenicov, Ana María. División Entomología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

Modeling population dynamics of yeast-like symbionts (Ascomycota: Pyrenomycetes: Clavicipitaceae) of the planthopper Delphacodes kuscheli (Hemiptera: Delphacidae)

Delphacodes kuscheli establish mutualistic relationship with yeast-like symbionts (YLS) that live in the fat body and are necessary for host survival and reproduction. We estimated for a host of age t, its body weight, W(t), and the number of YLS per host, YLS(t). The host body weight was calculated as: W(t) = Lm/[1+ e (d–kt)], (Lm = the maximum observed weight, and d and k are constants), and the fat body was considered a fixed proportion of W(t). We calculated the number of YLS per unit host body mass: α(t) = YLS(t)/W(t). We also calculated the number of YLS per host, cYLS(t), and analyzed the pattern of variation in both sexes adapting the expression of the logistic model: cYLS(t) = KNoert/K+(ert -1)No, (No = initial number of YLS, r = intrinsic per capita rate of natural increase, and K = variable carrying capacity). In females the carrying capacity varied according to a constant proportion of the host’s weight: K(t) = αW(t). In males α(t) was considered a decreasing function of the host age: K(t) = α(t)W(t). The coefficients No, α, and r were subjected to parameterization. We found that the patterns of W(t) and YLS(t) of D. kuscheli were similar to other planthoppers. In females YLS increased up to the adult stage and then remained almost constant, varying similarly to individual weight. In males YLS increased up to the 5th instar nymph as the individual weight did, but the number of YLS decreased in the adult stage and the correlation was not so good. The calculated number of YLS per host matches reasonably well with the number estimated experimentally both in females and males. This is the first study that quantified and modeled the dynamics of YLS endosymbionts in a Neotropical planthopper pest. The models will be used in future studies for better understand the experimental reduction of YLS in young nymphal stages.Centro de Estudios Parasitológicos y de VectoresFacultad de Ciencias Naturales y Muse