Artículos, informes y presentaciones en Congresos

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  • Resumen
    Acceso Abierto
    Antagonismo entre hongos entomopatógenos y bacterias presentes en la cutícula de cucarachas urbanas
    (2019) Lozano, Francisco; Gutierrez, Alejandra Concepción
    Las cucarachas son controladas principalmente mediante el uso de insecticidas orgánicos sintéticos. Una posible alternativa para el control es el uso de hongos entomopatógenos. Los ensayos que se realizaron en laboratorio con hongos entomopatógenos han tenido diferentes resultados dependiendo de la especie de cucaracha (Gutierrez et al., 2014; 2016). Para comprender las posibilidades del uso del control biológico con hongos en cucarachas, debemos iniciar los estudios en comprender la relación entre el hongo y la cutícula de las cucarachas. Datos de Gutierrez et al. 2015 y datos no publicados mostraron que la susceptibilidad a los hongos entomopatógenos es diferente en las especie de cucaracha analizada como fueron Blattella germanica (L.) (Blattodea: Blattellidae) y Periplaneta fuliginosa (S.) (Blattodea: Blattidae) . En una primer etapa se realizaron ensayos in-vitro con extractos cuticulares de las cucarachas mencionadas y comparando dos tratamientos con y sin antibiótico, se comprobó que la inhibición de la acción del hongo entomopatógeno Metarhizium anisopliae (Hypocreales: Clavicipitaceae) estaba relacionada a los microorganismos presentes en la cutícula de los insectos y no a la composición cuticular. Se procedió a aislar estos microorganismos. En este caso se pudo aislar una bacteria en cultivo puro, la cual fue identificada como Serratia marcescens por métodos moleculares. Esta bacteria se aisló de P. fuliginosa y coincide con la especie de cucaracha que presentó una mayor resistencia a la acción del hongo, en comparación con Blattella germanica que fue muy susceptible. El objetivo del trabajo fue comprobar in-vitro que la bacteria aislada inhibe el crecimiento del hongo. Materiales y métodos: Se realizó un antifungigrama para comprobar la inhibición de la bacteria hacia el hongo. Se sembraron en placas de Petri con SDYA ¼ 1x104 conidios /mL de M. anisopliae. Dentro de las cajas de Petri con el hongo se colocó un papel de filtro de 0.5 cm de diámetro conteniendo 6 μl de una suspensión de Serratia marcescens de 4.8 x 1010 UFC/ml. Se incubó durante 24 hs. a 25 °C. Se realizaron tres réplicas más un control. Transcurrido este periodo de tiempo, se observó la inhibición de las bacterias sobre el crecimiento fúngico. Resultados y discusión: se comprobó que esta bacteria inhibió el crecimiento y la esporulación del hongo M. anisopliae generando un halo de 0,5 cm de inhibición en el crecimiento fúngico y de 3 cm de inhibición de la esporulación. Conclusión general: los microorganismos presentes en la cutícula de las cucarachas analizadas podrían ser los responsables de la diferencia en la susceptibilidad hacia los hongos en las diferentes especies de cucarachas. Estos estudios permitirán ampliar el conocimiento para poder utilizarlo en el desarrollo de métodos de control biológico eficientes.
  • Artículo
    Acceso Abierto
    New association between the mite Erythraeus sp. (Acari: Prostigmata: Parasitengona) and the psyllid Russelliana adunca (Hemiptera: Psylloidea)
    (2021) Baliotte, Carla; Aquino, Daniel Alejandro; Dellapé, Gimena; López Armengol, María Fernanda; Gittins, Cecilia; Cédola, Claudia Viviana
    The association between the ectoparasitic mite, Erythraeus Latreille (Acari: Prostigmata: Parasitengona) and the psyllid Russelliana adunca Burckhardt (Hemiptera: Psylloidea) is reported for the first time. Larval erythraeid mites are not common on psyllids, therefore this first report adds a new host association and widens the distribution of the mite in South America.
  • Artículo
    Acceso Abierto
    First record of Heteropsylla tenuata from Argentina (Hemiptera: Psyllidae), and additional notes on other psyllid species
    (2021) Baliotte, Carla; Aquino, Daniel Alejandro; Bouvet, Juan P.; Dellapé, Gimena
    The Psyllidae family is the most diverse within Psylloidea, with more than 1,300 species worldwide. Some psyllid species are important pests mainly of fruit trees, forest and ornamental plants. Despite being an economically relevant group, there are few studies on its biology, geographic distribution, natural enemies or host plant associations for many Argentinean psyllid species. This work records one species from Argentina for the first time, extends the distribution of another two psyllid species and provides information on host plants.
  • Artículo
    Acceso Abierto
    Virulence and enzymatic activity of three new isolates of Beauveria bassiana (Ascomycota: Hypocreales) from the South American locust Schistocerca cancellata (Orthoptera: Acrididae)
    (2020) Pelizza, Sebastian A.; Medina, H.; Ferreri, N. A.; Elíades, Lorena; Pocco, Martina Eugenia; Stenglein, Sebastián; Lange, Carlos Ernesto
    Schistocerca cancellata is a large-sized acridid, which has historically represented the greatest agricultural problem in southern South America, causing serious economic losses. Since 2015 S. cancellata entered in a state of outbreak condition of historical proportions, producing frequent and large swarms of up to 25 km² in the north and central region of Argentina and areas of neigh boring Bolivia and Paraguay. At present, chemical insecticides are still the only means available for the control of S. cancellata. We analyzed under laboratory conditions the effectiveness of three fungal strains of Beauveria bassiana isolated from S. cancellata and also determined the relationship between chitinase, protease, and lipase levels at different temperatures of these fungi and their insecticidal activities. The pathogenicity assays were carried out by the sprayed method with concentrations of 1 × 10⁴, 1 × 10⁶ and 1 × 10⁸ conidia/ml. We observed that isolate LPSc 1227 caused the highest mortality at each dose studied, ranging from 100% at a dose of 1 × 10⁸ conidia/ml to 33.3 ± 3.2% at the lowest dose of 1 × 10⁴ conidia/ml. Moreover, in this isolate the highest values of chitinolytic and proteolytic activity were recorded (2.31 ± 0.31 and 1.78 ± 0.04), respectively.
  • Artículo
    Acceso Abierto
    Potential of spore-forming bacteria as biocontrol agents of wheat foliar diseases under laboratory and greenhouse conditions
    (2000) Alippi, Adriana Mónica; Perelló, Analía; Sisterna, Marina Noemí; Greco, Nancy Mabel; Cordo, Cristina Alicia
    The potential of Bacillus subtilis, Bacillus cereus, Bacillus licheniformis, Bacillus pumilus, Brevibacillus laterosporus and Paenibacillus polymyxa as biocontrol agents of four foliar necrotrophic pathogens of wheat in Argentina has been evaluated. The following assays were used: (a) effect of the bacterial antagonists on fungal growth in the central disk test with paired cultures, (b) effect of the antagonists on the germination of fungal spores in the paired suspension assay, and (c) reduction of disease severity in greenhouse experiments. The observed effects were specific for the antagonist-pathogen combination investigated. In the paired culture test, most of the bacterial antagonists inhibited the mycelial growth of the four pathogens tested at 14 days of the evaluation. B. licheniformis showed the best results for controlling Septoria tritici and Drechslera tritici-repentis whereas it was the worst against Bipolaris sorokiniana. In the case of Alternaria triticimaculans, the best were B. laterosporus, P. polymyxa and B. licheniformis. Microscopic examination of excised pieces of the fungal colony perimeters showed clear differences among treatments and controls in hyphal morphology (plasmolysis and vacuolation of hyphae, irregular texture in the cytoplasm, formation of chlamydospores). In the central disk test, mycelial necrosis of A. triticimaculans was induced by B. laterosporus, P. polymyxa and B. pumilus. Similar results were obtained with B. sorokiniana in the presence of B. licheniformis and B. subtilis and D. tritici-repentis with B. pumilus. In some combinations, the presence of inhibition haloes or bacterial chemotaxis were observed. In the paired suspension assay, all the bacteria except B. cereus, inhibited the conidial germination of S. tritici. Only P. polymyxa, B. licheniformis and B. laterosporus inhibited the conidial germination of A. triticimaculans, B. laterosporus being the most effective. Although all the bacteria inhibited the conidial germination of B. sorokiniana, the most efficient were B. licheniformis, B. cereus and B. laterosporus. In greenhouse experiments, P. polymyxa and B. cereus were the most efficient to reduce disease severities produced by S. tritici and A. triticimaculans; on the contrary, these bacteria were not effective against B. sorokiniana and D. tritici-repentis. B. laterosporus BLA 170 showed a good behaviour against all the fungal pathogens, particularly for D. tritici-repentis and B. sorokiniana. This is the first report on the efficacy of B. laterosporus against fungal wheat pathogens.
  • Artículo
    Acceso Abierto
    Effects of endophytic Beauveria bassiana (Ascomycota: Hypocreales) on biological and reproductive parameters and food preference of the soybean pest Helicoverpa gelotopoeon
    (Science Direct, 2019) Russo, María Leticia; Scorsetti, Ana Clara; Vianna, María Florencia; Allegrucci, Natalia; Ferreri, Natalia; Cabello, Marta Noemí; Pelizza, Sebastian A.
    Objectives: We studied Beauveria bassiana ability to endophytic colonize soybean and its effects on some biological and reproductive parameters and on the food preference of Helicoverpa gelotopoeon, a polyphagous plague of several agronomic crops. Methods: A suspension of 1x108 conidia ml-1 of B. bassiana (LPSC 1098), was inoculated in soybean plants using the leaf spraying method. H. gelotopoeon survival, developement, fecundity and fertility were registered to evaluate fungal effect. Also, food preference was determined by the free-choice method. Results: B. bassiana as an endophyte adversely affected the duration of the larval stages (L1, L2, L3, L4) and of the adult stages, as well as the total duration of the life cycle. Furthermore, the oviposition period, fecundity and fertility of H. gelotopoeon decreased. This is the first report of decreased consumption of soybean leaves by H. gelotopoeon due to endophytic B. bassiana. Conclusions: This investigation shows that endophytic fungi could be considered as useful microorganisms for the integrated pest management
  • Artículo
    Acceso Abierto
    HiCrome Bacillus agar for presumptive identification of Bacillus and related species isolated from honey samples
    (2019) Alippi, Adriana Mónica; Abrahamovich, Eliana
    This study aimed to evaluate the performance of Hicrome Bacillus™ agar for isolation and rapid identification of the aerobic spore-forming bacteria most frequently found in honey samples. A collection of 197 bacterial isolates of Bacillus, Brevibacillus, Lysinibacillus, Paenibacillus, and Rummeliibacillus belonging to different species that have been reported in honey were screened for their abilities to grow and for their colony colors and medium appearance in HiCrome Bacillus agar. Also, 21 strains from culture collections were used for comparison and quality controls. A flowchart utilizing a combination of colony and media characteristics in the chromogenic medium and a set of simple biochemical and morphological tests were elaborated for quick presumptive identification. A procedure for direct isolation from honey samples was developed. In conclusion, HiCrome Bacillus agar in combination with simple microbiological tests was highly useful for rapid and reliable identification of most Bacillus, Brevibacillus, Lysinibacillus and Paenibacillus species commonly found in honey samples facilitating isolation from polymicrobial honey.
  • Comunicacion
    Acceso Abierto
    Longevity and fecundity of Dichroplus maculipennis (Orthoptera, Acrididae) at non-outbreaking and outbreaking situations
    (2011) Mariottini, Yanina; De Wysiecki, Laura; Lange, Carlos Ernesto
    Longevity and fecundity of Dichroplus maculipennis (Orthoptera, Acrididae) at non-outbreaking and outbreaking situations. Dichroplus maculipennis is one of the most characteristic and damaging grasshopper species of Argentina, mainly in areas of the Pampas and Patagonia regions. We estimated and compared the longevity and fecundity of adult female D. maculipennis under controlled conditions (30°C, 14L:10D, 40% RH) from individuals collected as last instar nymphs (VI) in the field and with a known recent history of low and high density conditions. Densities of D. maculipennis at the collecting sites were 0.95 individuals per m2 in 2006 and 46 ind/m2 in 2009, representing non-outbreaking and outbreaking situations, respectively. Adult female longevity in 2006 (67.96 ± 3.2 days) was significantly higher (p < 0.05) than in 2009 (37.44 ± 1.98 days). The number of egg-pods per female was 3.32 ± 0.44 for 2006 and 1.62 ± 0.26 for 2009. The average fecundity in 2006 (89.29 ± 11.9 eggs/female) was significantly greater (p < 0.05) than that in 2009 (36.27 ± 5.82 eggs/female). While it was observed that the oviposition rate was higher in 2006, this difference was not significant (p > 0.05). The fecundity curves showed that the highest values were at weeks 11 and 13 for the 2006 females, and at week 6 for those of 2009. Since the daily oviposition rate at low and high densities was not significantly different, the diminished fecundity rate at high density is attributable to their reduced longevity
  • Documento de conferencia
    Acceso Abierto
    Manejo integrado de plagas en el cinturón hortícola platense
    (2018) Navone, Graciela
    El Laboratorio de Ecología de Plagas y Control Biológico del CEPAVE realiza investigación científica para el manejo de plagas en distintos sistemas productivos, entre ellos en el Cinturón Hortícola Platense (Buenos Aires), con énfasis en el control biológico por medio de la acción de enemigos naturales – en este caso agentes de control biológico – nativos o de presencia espontánea. Es decir, se hace hincapié en el aprovechamiento de los recursos naturales propios de la región. Los estudios abordan la ecología de insectos y ácaros plaga, así como de sus enemigos naturales: ciclos de vida, demografía, efectividad de control, desempeño sobre distintas plantas, variaciones poblacionales, interacciones entre agentes. La finalidad de estas investigaciones es conocer más acerca de las principales plagas en los cultivos hortícolas y desarrollar programas de CB mediante depredadores (Figura 2.A) y parasitoides nativos o establecidos. Se pretende mejorar el manejo sanitario de la producción en estos cultivos, contribuyendo con alternativas para reducir el uso de plaguicidas químicos en el contexto del MIP.
  • Documento de conferencia
    Acceso Abierto
    Desarrollo de una estrategia compatible con el ambiente para la mitigación de la problemática causada por los simúlidos (Barigüí) en el Río Salado, provincia de Buenos Aires
    (2018) García, Juan José; Ordoqui, Eliana; Carlos, F.
    Las localidades ubicadas a lo largo de la cuenca del río Salado en la provincia de Buenos Aires sufren desde hace dos décadas las molestias, problemas de salud y pérdidas económicas, provocadas por la acción de insectos hematófagos de la Familia Simuliidae (simúlidos - barigüí). El presente proyecto intenta investigar la/s especie/s involucrada7s, biología y ecología de la/s misma/s, variación estacional de los estados inmaduros y de los adultos, y los factores ambientales que influyen en esas variaciones, como información esencial para poder implementar medidas de control racionales y compatibles con el ambiente.
  • Artículo
    Acceso Abierto
    Efectos de la calidad del alimento en la tucura Dichroplus pratensist Bruner (Orthoptera: Acrididae)
    (1996) Pereyra, Patricia; Sánchez, Norma Elba; Wysiecki, María Laura de
    Los acridios están frecuentemente asociados a plantas que sufren estrés hídrico y térmico, en pastizales con sequías estacionales marcadas. El objetivo de este trabajo fue evaluar el efecto de hojas de maíz, Zea mays, sometidas a marchitamiento artificial, en el comportamiento alimentario, la supervivencia y la fecundidad de Dichroplus praiensis en laboratorio. Se utilizaron hojas turgentes y hojas marchitas para evaluar la preferencia alimentaria, tasas de consumo, crecimiento y eficiencia de conversión de alimento. Se computó la supervivencia diaria, la duración del 5to estadio nínfal, el período de preoviposición y la fecundidad en hembras criadas con ambos tipos de alimentos. Tanto ninfas de 5to estadio como adultos mostraron una marcada preferencia por el alimento marchito. Las ninfas alimentadas con hojas marchitas crecieron y consumieron más que las alimentadas con hojas turgentes. En los adultos, hubo una mayor tendencia al consumo de alimento marchito, sin embargo, no se hallaron diferencias entre alimentos para la tasa de crecimiento relativo. No hubo tampoco diferencias entre tratamientos en la supervivencia, duración del 5to estadio ninfal, período de preoviposición y fecundidad.
  • Artículo
    Acceso Abierto
    Effect of endophytic entomopathogenic fungi on soybean Glycine max (L.) Merr. growth and yield
    (Science Direct, 2018) Russo, M. L.; Pelliza, S. A.; Vianna, M. F.; Allegrucci, N.; Cabello, Marta Noemí; Toledo, Andrea Vanesa; Mourelos, C.; Scorsetti, A. C.
    The soybean is a crop of economic importance and has a great number of potential pests which cause significant economic losses. The entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae and Metarhizium robertsii are important biological control agents, which can live as endophytes within plants and causes no apparent damage to the host. The aims of this study were to assess whether the entomopathogenic fungi B. bassiana, M. manisopliae and M. robertsii are able to colonize soybean plants as endophytes by using different inoculation techniques; and assess if these fungi produce any effect on the growth and yield of soybean plants under field conditions. We demonstrate the effectiveness of three inoculation methods (foliar spray, seed immersion and root immersion) to establish fungal entomopathogens as endophytes. Percentage of recovery for the different fungal strains was higher after 7 days of inoculation, through the organ that was in direct contact with the fungus during the inoculation. B. bassiana LPSc 1098 inoculated by leaf aspersion was the most successful strain. It was also demonstrated for the first time that inoculation with B. bassiana promoted the growth and increased the yield of soybean plants under filed conditions, with no adverse effects observed in the inoculated plants.
  • Artículo
    Acceso Abierto
    Control biológico de la polilla del tomate Tuta absoluta (Lepidóptera: Gelechiidae): eficiencia de búsqueda y capacidad de vuelo de las hembras de Pseudapanteles dignus (Hymenoptera: Braconidae)
    (2018) Salas Gervassio, Nadia Gisela; Vallina, Consuelo; Rochi, Victorio; Luna, María Gabriela; Sánchez, Norma Elba
    En este trabajo se estudió la eficiencia de búsqueda de las hembras de Pseudapanteles dignus para encontrar y parasitar a larvas de Tuta absoluta y la capacidad de vuelo de las mismas en un invernáculo experimental. Las hembras mostraron una baja eficiencia de parasitismo y una buena capacidad de vuelo durante el período de observación ensayado.
  • Artículo
    Acceso Abierto
    Biodiversity of entomonematodes parasitizing soil pest white grubs (Scarabaeidae) of Buenos Aires, Argentina
    (2014) Camino, Nora Beatriz; Achinelly, María Fernanda; Rusconi, José Matías; Eliceche, Daiana; Salas, Augusto
    This work was carried out between 2006-2010 in wheat fields of the Pampas, Argentina, in order to determine species of nematode parasites and pathogens of white grubs, soil major pest. Samples were taken with shovel in randomly selected sites. Nymphs of Diloboderus abderus and Cyclocephalla signaticollis (Scarabaeidae) were collected. Thirteen species of nematodes belonging to 5 families (Mermithidae, Thelastomatidae, Travassonematidae, Diplogasteridae and Rhabditidae) were determined. The richness species values were 1 for Cyclocephalla signaticollis and 12 for Diloboderus abderus. The thelastomatids and rhabdítids were the largest group of nematodes, with a total of 3 species each. The thelastomátids were very prevalent with infections exceeded 60%, followed by diplogasterids which reached 36%. The mermítids were less prevalent with values close to 10%. The family Travossonematidae was the one with the lowest abundance (0.32). Knowledge of nematode community will be a great ability to interpret host-parasite relationships and in many cases determine those species pest potential bioreguladoras important agents in agricultural areas of Argentina. This study provides for the first time to the Pampas region of our country a list of white worms parasitic nematodes.
  • Artículo
    Acceso Abierto
    Nematodes (Mermithidae) parasitizing grasshoppers (Orthoptera: Acrididae) in the Pampean region, Argentina
    (2017) Rusconi, José Matías; Camino, Nora Beatriz; Achinelly, María Fernanda
    This work provides the results of a survey of entomonematodes parasites of grasshoppers in grasslands of the Pampean Region, Argentina. Nymphs of Staurorhectus longicornis Giglio-Tos, Laplatacris dispar Rhen, 1939, Dichroplus elongatus Giglio-Tos, 1894 and Metaleptea brevicornis (L.) (Orthoptera: Acrididae) were collected. Mermithidae was the only family registered with seven species: Agamermis decaudata Cobb, Steiner and Christie, 1923, Amphimermis bonaerensis Miralles and Camino, 1983, Amphimermis dichroplusi Camino and Lange, 1997, Amphimermis ronderosi Camino and Lange, 1997, Hexamermis coclhearius Stock and Camino, 1992, Hexamermis ovistriata Stock and Camino, 1992, and Longimermis acridophila Camino and Stock, 1989. The values of parasitism ranged between 1-12%, and intensity not overcome the number of 5.0 nematodes per larva. The nematodes observed showed specificity, not registering the same species of parasite in more than one host species. The Pampean region constituted an area with high diversity of mermithids where new species could be consider as bioregulator agents of this troublesome insect pests in agricultural areas of Argentina.
  • Artículo
    Acceso Abierto
    Contribución de la vegetación silvestre al mantenimiento de servicios ecosistémicos: control biológico por conservación de la “polilla del tomate” Tuta absoluta (Lepidoptera: Gelechiidae)
    (2015) Salas Gervassio, Nadia Gisela; Luna, María Gabriela; Sánchez, Norma Elba
    El objetivo es conocer las relaciones entre Tuta absoluta, su parasitoide Pseudapanteles dignus y solanáceas silvestres presentes en predios hortícolas, para contribuir al control biológico por conservación de T. absoluta mediante manejo del hábitat. Exploramos la abundancia anual de geléquidos minadores en solanáceas silvestres y el parasitismo por P. dignus en siete predios. Tuta absoluta estuvo presente en 4 especies de solanáceas silvestres y P. dignus parasitó sólo a T. absoluta. La interacción T. absoluta-P. dignus se observó en tres especies de solanáceas de los alrededores del cultivo por períodos prolongados de varios meses, y en conjunto se mantuvo funcional durante casi todo el año. Esto sugiere que estas especies estarían actuando como fuente de dispersión del parasitoide hacia el cultivo, compensando el disturbio de los cultivos anuales, y contribuyendo a evitar la extinción del servicio ecológico que presta este parasitoide en limitar naturalmente a la plaga en tomate.
  • Artículo
    Embargado
    Factors Related to Aedes aegypti (Diptera: Culicidae) Populations and Temperature Determine Differences on Life-History Traits With Regional Implications in Disease Transmission
    (Oxford University Press, 2018) Muttis, Evangelina; Balsalobre, Agustín; Chuchuy, Ailen; Mangudo, Carolina; Ciota, Alexander T.; Kramer, Laura D.; Micieli, María Victoria
    Aedes aegypti (L.) (Diptera: Culicidae) is a vector of many medically significant viruses in the Americas, including dengue virus, chikungunya virus, and Zika virus. Traits such as longevity, fecundity, and feeding behavior contribute to the ability of Ae. aegypti to serve as a vector of these pathogens. Both local environmental factors and population genetics could contribute to variability in these traits. We performed a comparative study of Ae. aegypti populations from four geographically and environmentally distinct collection sites in Argentina in which the cohorts from each population were held at temperature values simulating a daily cycle, with an average of 25°C in order to identify the influence of population on life-history traits. In addition, we performed the study of the same populations held at a daily temperature cycle similar to that of the surveyed areas. According to the results, Aguaray is the most outstanding population, showing features that are important to achieve high fitness. Whereas La Plata gathers features consistent with low fitness. Iguazu was outstanding in blood-feeding rate while Posadas’s population showed intermediate values. Our results also demonstrate that climate change could differentially affect unique populations, and that these differences have implications for the capacity for Ae. aegypti to act as vectors for medically important arboviruses.
  • Artículo
    Embargado
    Population dynamics between the mermithid Strelkovimermis spiculatus (Nematoda: Mermithidae) and the floodwater mosquito Ochlerotatus albifasciatus (Diptera: Culicidae) over time
    (Elsevier, 2012) María V. Micieli, Paula Risso, María F. Achinelly , M. de los Milagros Villar, Evangelina Muttis; Micieli, María Victoria; Risso, Paula; Achinelly, María Fernanda; Villar, María de los Milagros; Muttis, Evangelina
    We investigated the population dynamics of Strelkovimermis spiculatus in Ochlerotatus albifasciatus to determine the abiotic and biotic parameters involved in this host-parasite system. Weekly samplings performed from May 2007 through May 2010 in three ponds located in open areas of La Plata, Argentina revealed that parasitism by S. spiculatus in O. albifasciatus occurred throughout all seasons with differences in effectiveness among breeding habitats: A mosquito-larva reduction of 80.7% was observed in a habitat where 100% of the generations were infected by nematodes; an intermediate situation (a 41.9% reduction) involved a lower percentage of parasitism above 50% although nematode infection was likewise registered in 92.9% of the generations. Finally, a mosquito-larva reduction of 2.68% was recorded where only 46.0% of the generations were parasitized and at levels of nematode infection below 50%. We analyzed the effects of abiotic and biotic parameters on S. spiculatus infections. The floodedsurface area was the only variable significantly associated with percent infection. Infection prevalence correlated positively with the mean number of emerged nematodes per larva and with the S. spiculatus male-to-female ratio in each parasitized-mosquito generation. In conclusion, the frequency over time and levels of infection are key parameters in the regulation of mosquito populations by this mermithid
  • Artículo
    Embargado
    Transmission of a pathogenic virus (Iridoviridae) of Culex pipiens larvae mediated by the mermithid Strelkovimermis spiculatus (Nematoda)
    (Elsevier, 2015) Muttis, Evangelina; Micieli, María Victoria; Urrutia, María Inés; García, Juan José
    Little progress been made in elucidating the transmission pathway of the invertebrate iridescent virus (MIV). It has been proposed that the MIV has no active means to enter the mosquito larva. We have previously found that the presence of the mermithid nematode Strelkovimermis spiculatus is associated with MIV infection in Culex pipiens under field conditions. In the present study, we evaluated the transmission of MIV to C. pipiens larvae mediated by S. spiculatus and several factors involved in this pathway (mosquito instars, nematode:mosquito larva ratio, amount of viral inoculum). Our results indicate that S. spiculatus functions as an MIV vector to C. pipiens larvae and seems to be an important pathway of virus entry into this system. Moreover, TEM images of S. spiculatus exposed to the viral suspension showed no infections inside the nematode but showed that viral particles are carried over the cuticle of this mermithid. This explains the correspondence between MIV infection and the factors that affect the parasitism of S. spiculatus in C. pipiens larvae.
  • Artículo
    Embargado
    Culex pipiens affected by joint infection of a mosquito iridescent virus and Strelkovimermis spiculatus
    (Elsevier, 2013) Muttis, Evangelina; Micieli, María Victoria; García, Juan José
    Dual infections with a mosquito iridescent virus (MIV) and the mermithid nematode, Strelkovimermis spiculatus were recorded in natural Culex pipiens populations around La Plata city, Argentina. S. spiculatus was detected in 82% of samples that were positive for MIV infection. Dissected larvae of Cx. pipiens with patent MIV infection presented 42% infection with S. spiculatus. Larvae of Cx. pipiens exposed to MIV and S. spiculatus under laboratory conditions produced a high joint infection rate (82.5%) while no infection was recorded on larvae exposed to virus suspension only. Field and laboratory results suggest a strong association between S. spiculatus and MIV in natural populations of Cx. pipiens, in which S. spiculatus could be a mode of entry for the virus into the mosquito hemocele.