First record of <i>Fusarium verticillioides</i> as an entomopathogenic fungus of grasshoppers

Fusarium verticillioides (Saccardo) Nirenberg (Ascomycota: Hypocreales) is the most common fungus reported on infected corn kernels and vegetative tissues, but has not yet been documented as being entomopathogenic for grasshoppers. Grasshoppers and locusts represent a large group of insects that cause economic damage to forage and crops. Tropidacris collaris (Stoll) (Orthoptera: Acridoidea: Romaleidae) is a large and voracious grasshopper that in recent years has become an increasingly recurrent and widespread pest in progressively more greatly extended areas of some of in Argentina's northern provinces, with chemical insecticides being currently the only means of control. During February and March of 2008-09, nymphs and adults of T. collaris were collected with sweep nets in dense woodland vegetation at a site near Tres Estacas in western Chaco Province, Argentina, and kept in screened cages. F. verticillioides was isolated from insects that died within 10 days and was cultured in PGA medium. Pathogenicity tests were conducted and positive results recorded. Using traditional and molecular-biological methods, an isolate of F. verticillioides was obtained from T. collaris, and its pathogenecity in the laboratory was shown against another harmful grasshopper, Ronderosia bergi (Stål) (Acridoidea: Acrididae: Melanoplinae). The mortality caused by F. verticillioides on R. bergi reached 58 ± 6.53% by 10 days after inoculation. This is the first record of natural infection caused by F. verticillioides in grasshoppers.Instituto de Botánica "Dr. Carlos Spegazzini

First record of <i>Fusarium verticillioides</i> as an entomopathogenic fungus of grasshoppers

Fusarium verticillioides (Saccardo) Nirenberg (Ascomycota: Hypocreales) is the most common fungus reported on infected corn kernels and vegetative tissues, but has not yet been documented as being entomopathogenic for grasshoppers. Grasshoppers and locusts represent a large group of insects that cause economic damage to forage and crops. Tropidacris collaris (Stoll) (Orthoptera: Acridoidea: Romaleidae) is a large and voracious grasshopper that in recent years has become an increasingly recurrent and widespread pest in progressively more greatly extended areas of some of in Argentina's northern provinces, with chemical insecticides being currently the only means of control. During February and March of 2008-09, nymphs and adults of T. collaris were collected with sweep nets in dense woodland vegetation at a site near Tres Estacas in western Chaco Province, Argentina, and kept in screened cages. F. verticillioides was isolated from insects that died within 10 days and was cultured in PGA medium. Pathogenicity tests were conducted and positive results recorded. Using traditional and molecular-biological methods, an isolate of F. verticillioides was obtained from T. collaris, and its pathogenecity in the laboratory was shown against another harmful grasshopper, Ronderosia bergi (Stål) (Acridoidea: Acrididae: Melanoplinae). The mortality caused by F. verticillioides on R. bergi reached 58 ± 6.53% by 10 days after inoculation. This is the first record of natural infection caused by F. verticillioides in grasshoppers.Instituto de Botánica "Dr. Carlos Spegazzini

Compatibility of chemical insecticides and entomopathogenic fungi for control of soybean defoliating pest, Rachiplusia nu.

Fil: Pelizza, Sebastián Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios en Parasitología y Vectores; ArgentinaFil: Schalamuk, Santiago. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica; ArgentinaFil: Simón, María Rosa. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; ArgentinaFil: Stenglein, Sebastián Alberto. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomía. Laboratorio de Biología Funcional y Biotecnología. Azul; ArgentinaFil: Pacheco Marino, Suani Giovanna. Instituto de Genética Veterinaria Ingeniero Fernando Noel Dulout. La Plata; ArgentinaFil: Scorsetti, Ana Clara. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Carlos Spegazzini; Argentin

Common Bean Germplasm Molecular Analysis: A Biotechnological Approach for Breeding

Argentina, which is a major producer of common bean (Phaseolus vulgaris L.), represents the southern most limit of the Andean diversification center of the species. The diverse environmental conditions of these places and human selection favored the development of a great variability of wild beans and landraces, which is endangered due to the destruction of habitats by forest exploitation and agriculture. Information on the variability of these resources is essential to set conservation strategies and design breeding programs aimed at enlarging the genetic base of commercial beans. This work is an overview of the marker-based studies on landraces and wild bean genetic diversity, with special emphasis on Argentinean beans, as a first step for the optimal exploitation of the naturally available bean genetic resources, to generate new traits and improve crop performance. The identification of diversity and hybridization between populations is enhanced by the application of the new tools and the information generated by bean genomic research. Gene flow, which appears to occur fairly frequently in bean, has to be studied in more detail in this region in order to facilitate the transfer of useful alleles from the unexploited germplasm to improved lines, broadening the genetic diversity available for breeding. Some resistance gene analogs (RGAs) have been described within the Andean gene pool and only a few have been functionally characterized or linked to a phenotype. Therefore, a strategy for the exploitation of bean germplasm variability based on the detection of RGAs is also mentioned, though more work should be devoted at identifying these sequences in Andean landraces and wild beans.Facultad de Ciencias Agrarias y Forestale

Pathogenic and enzyme activities of the entomopathogenic fungus <i>Tolypocladium cylindrosporum</i> (Ascomycota: Hypocreales) from Tierra del Fuego, Argentina

Tolypocladium cylindrosporum is an entomopathogenic fungi that has been studied as a biological control agent against insects of several orders. The fungus has been isolated from the soil as well as from insects of the orders Coleoptera, Lepidoptera, Diptera and Hymenoptera. In this study, we analyzed the ability of a strain of T. cylindrosporum, isolated from soil samples taken in Tierra del Fuego, Argentina, to produce hydrolytic enzymes, and to study the relationship of those activities to the fungus pathogenicity against pest aphids. We have made the traditional and molecular characterization of this strain of T. cylindrosporum. The expression of hydrolase activity in the fungal strain was estimated at three incubation temperatures (4ºC, 12ºC and 24ºC), on different agar media supplemented with the following specific substrates: chitin azure, Tween ® 20, casein, and urea for chitinase, lipase, protease, and urease activity, respectively. The hydrolytic-enzyme activity was estimated qualitatively according to the presence of a halo of clarification through hydrolase action, besides was expressed semi-quantitatively as the ratio between the hydrolytic-halo and colony diameters. The pathogenicity of the fungus was tested on adults of the aphid Rhopalosiphum padi at three temperatures of incubation (4ºC, 12ºC and 24ºC). The suspension was adjusted to a concentration of 1x10 7 conidia/ml. In pathogenicity assays at seven days post-inoculation, the fungus caused the mortality of adults of Ropalosiphum padi at different temperatures also showed a broad ability to grow on several agar-culture media, supplemented with different carbon sources at the three incubation temperatures tested. Although, the growth was greater with higher incubation temperatures (with maximum levels at 24°C), the fungus reached similar colony diameters after 15 days of incubation on the medium supplemented with Tween® 20 at the lower two incubation temperatures of 4°C or 12°C. In accordance with the results on colony diameters, the fungus revealed an ability to degrade casein, chitin derivatives, Tween® 20, and urea as evidenced by the appearance of a halo around the fungal colony. Because of its origin and temperature tolerance, this Argentine strain has great potential for use as a biocontrol agent for insect pest control in cold and temperate environments.Facultad de Ciencias Agrarias y Forestale

Compatibility between entomopathogenic fungi and biorational insecticides in toxicity against <i>Ronderosia bergi</i> under laboratory conditions

Our aim was to evaluate the efficacy of combinations between two biorational insecticides (luphenuron, methoxyfenozide), a new synthetic chemical pesticide (rynaxypyr), and three entomopathogenic fungi strains (Beauveria bassiana LPSc 1067, LPSc1082), and Metarhizium anisopliae (LPSc 907) in the biocontrol of the pest grasshopper Ronderosia bergi (Sta°l) under laboratory conditions. The insecticides were tested at three concentrations: the average concentration recommended for application in the field (100 %) and 50 % and finally 25 % of that level. The fungal strains used were adjusted to 1 9 108, 1 9 106, and 1 9 104 conidia ml-1. The combinations of those insecticides with B. bassiana (LPSc 1067, LPSc 1082) and M. anisopliae (LPSc 907) caused higher mortality to R. bergi nymphs than any of the individual agents used alone. The three insecticides tested did not affect the isolates of the two species of entomopathogenic fungi employed. In conclusion, the use of these biorational insecticides in an IPM program aimed at control of the grasshopper R. bergi could be of value.Facultad de Ciencias Naturales y Muse

Endophytic colonisation of tobacco, corn, wheat and soybeans by the fungal entomopathogen <i>Beauveria bassiana</i> (Ascomycota, Hypocreales)

We demonstrate the effectiveness of three inoculation methods (foliar spray, seed immersion and root immersion) in establishing fungal the entomopathogen Beauveria bassiana as an endophyte in tobacco, corn, wheat and soybean. Colonisation of leaves by B. bassiana was assessed 7, 14, 21 and 28 days post-inoculation. There were significant differences (p < 0.001) in endophytic colonisation among the different inoculation techniques.Facultad de Ciencias Naturales y MuseoInstituto de Botánica "Dr. Carlos Spegazzini"Centro de Estudios Parasitológicos y de Vectore

Compatibility between entomopathogenic fungi and biorational insecticides in toxicity against <i>Ronderosia bergi</i> under laboratory conditions

Our aim was to evaluate the efficacy of combinations between two biorational insecticides (luphenuron, methoxyfenozide), a new synthetic chemical pesticide (rynaxypyr), and three entomopathogenic fungi strains (Beauveria bassiana LPSc 1067, LPSc1082), and Metarhizium anisopliae (LPSc 907) in the biocontrol of the pest grasshopper Ronderosia bergi (Sta°l) under laboratory conditions. The insecticides were tested at three concentrations: the average concentration recommended for application in the field (100 %) and 50 % and finally 25 % of that level. The fungal strains used were adjusted to 1 9 108, 1 9 106, and 1 9 104 conidia ml-1. The combinations of those insecticides with B. bassiana (LPSc 1067, LPSc 1082) and M. anisopliae (LPSc 907) caused higher mortality to R. bergi nymphs than any of the individual agents used alone. The three insecticides tested did not affect the isolates of the two species of entomopathogenic fungi employed. In conclusion, the use of these biorational insecticides in an IPM program aimed at control of the grasshopper R. bergi could be of value.Facultad de Ciencias Naturales y Muse

Pseudopithomyces chartarum associated with wheat seeds in Argentina, pathogenicity and evaluation of toxigenic ability

Argentina is one of the top 10 world producers and exporters of wheat. In routine surveys of wheat (Triticum aestivum L.) in Buenos Aires Province, Argentina, a new disease was observed in 2012 on seeds of wheat cv. Buck Meteoro. Symptomatic grains (black points) and leaves (chlorosis and spots) were collected during the spring of that year. The objectives of the present study were to identify the causal agent, to investigate its pathogenicity in relation to nine wheat cultivars and to identify the secondary metabolites produced by fungus. Symptomatic grains were plated on potato dextrose agar (PDA). Morphological characterization of colonies and sequencing of the ITS region after DNA extraction identified it as Pseudopithomyces chartarum. For pathogenicity tests, two different isolates, P221 and P224, were inoculated on seedlings of nine wheat cultivars, which showed different disease symptoms, % of grain germination (GG), % of grain discoloration (GD) and % of weak seedlings (WS), suggesting different levels of response against Pseudopithomyces chartarum. Particularly B. Meteoro, Buck Guapo and Klein Proteo cultivars demonstrated major infection tolerance for GD and WS. In contrast, Sy 100 and Klein Pantera were most affected showing weakness, chlorosis, or reduced length of coleoptile, and 50% of necrotic symptoms. Pseudopithomyces chartarum isolates produced secondary metabolites including alternariol, alternariol mono-methyl ether, altertoxin I and altertoxine II. The fungus is a new pathogen of wheat in Argentina that can cause diseases on different cultivars as well as produce mycotoxins.Facultad de Ciencias Agrarias y Forestale

Pathogenic and enzyme activities of the entomopathogenic fungus <i>Tolypocladium cylindrosporum</i> (Ascomycota: Hypocreales) from Tierra del Fuego, Argentina

Tolypocladium cylindrosporum is an entomopathogenic fungi that has been studied as a biological control agent against insects of several orders. The fungus has been isolated from the soil as well as from insects of the orders Coleoptera, Lepidoptera, Diptera and Hymenoptera. In this study, we analyzed the ability of a strain of T. cylindrosporum, isolated from soil samples taken in Tierra del Fuego, Argentina, to produce hydrolytic enzymes, and to study the relationship of those activities to the fungus pathogenicity against pest aphids. We have made the traditional and molecular characterization of this strain of T. cylindrosporum. The expression of hydrolase activity in the fungal strain was estimated at three incubation temperatures (4ºC, 12ºC and 24ºC), on different agar media supplemented with the following specific substrates: chitin azure, Tween ® 20, casein, and urea for chitinase, lipase, protease, and urease activity, respectively. The hydrolytic-enzyme activity was estimated qualitatively according to the presence of a halo of clarification through hydrolase action, besides was expressed semi-quantitatively as the ratio between the hydrolytic-halo and colony diameters. The pathogenicity of the fungus was tested on adults of the aphid Rhopalosiphum padi at three temperatures of incubation (4ºC, 12ºC and 24ºC). The suspension was adjusted to a concentration of 1x10 7 conidia/ml. In pathogenicity assays at seven days post-inoculation, the fungus caused the mortality of adults of Ropalosiphum padi at different temperatures also showed a broad ability to grow on several agar-culture media, supplemented with different carbon sources at the three incubation temperatures tested. Although, the growth was greater with higher incubation temperatures (with maximum levels at 24°C), the fungus reached similar colony diameters after 15 days of incubation on the medium supplemented with Tween® 20 at the lower two incubation temperatures of 4°C or 12°C. In accordance with the results on colony diameters, the fungus revealed an ability to degrade casein, chitin derivatives, Tween® 20, and urea as evidenced by the appearance of a halo around the fungal colony. Because of its origin and temperature tolerance, this Argentine strain has great potential for use as a biocontrol agent for insect pest control in cold and temperate environments.Facultad de Ciencias Agrarias y Forestale