Nuevos registros de garrapatas (Acari: Ixodidae) asociadas a roedores sigmodontinos en Chubut, Argentina

Se reportan nuevos hallazgos de garrapatas obtenidas de roedores capturados en sitios cercanos a Cholila (42o31'S, 71o27'W), provincia del Chubut (Argentina). Se registraron las siguientes asociaciones parásito-hospedador: Oligoryzomys lonngicaudatus: 1 larva de Amblyomma tigrinum, 1 hembra de Ixodes sigelos, 2 ninfas de I. sigelos; Reithrodon auritus: 1 hembra de I. sigelos; Loxodontomys micropus: 1 ninfa de I. sigelos; Chelemys macronyx: 7 larvas de I. sigelos. Ixodes sigelos no ha sido reportada previamente en C. macronyx, así como tampoco A. tigrinum sobre O. longicaudatus. Estos resultados brindan nueva evidencia del rol fundamental que cumplen los roedores en el ciclo biológico de algunas garrapatas presentes en la Argentina.We report new findings of ticks from rodents trapped at different sites near Cholila (42o31’S, 71o27’W), Chubut Province (Argentina). The following host-parasite associations were recorded: Oligoryzomys longicaudatus: 1 larva of Amblyomma tigrinum, 1 female of Ixodes sigelos, 2 nymphs of I. sigelos; Reithrodon auritus: 1 female of I. sigelos; Loxodontomys micropus: 1 nymph of I. sigelos; Chelemys macronyx: 7 larvae of I. sigelos. Ixodes sigelos has not been previously reported on C. macronyx as well as not A. tigrinum on O. longicaudatus. These results provide new evidence about the fundamental role of rodents in the life cycle of some ticks present in Argentina.Fil: Mastropaolo, Mariano. Universidad Nacional del Litoral; ArgentinaFil: Martin, Gabriel Mario. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nava, Santiago. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Ornithodoros quilinensis sp. nov. (Acari, Argasidae), a new tick species from the Chacoan region in Argentina

Ornithodoros quilinensis sp. nov. (Acari: Argasidae) is described from larvae collected on the small rodents Graomys centralis (Cricetidae: Sigmodontinae) in Argentina. The diagnostic characters for this new species are a combination of small size (520-540 μm), a dorsal plate oval in shape with a length of approximately 200 μm, 14 pairs of dorsal setae, hypostome short and narrower at the base (length from Ph1 to apex 133 μm (120-141)) with dental formula 2/2 and apex blunt, and the capsule of the Haller's organ irregular in shape and without reticulations. The analysis of the 16S rDNA sequences available for the genus Ornithodoros indicate that, phylogenetically, O. quilinensis represents an independent lineage only related to a Bolivian tick species of the genus Ornithodoros yet not formally described.Fil: Venzal, José M.. Universidad de la Republica, Salto; UruguayFil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria Eea, Rafaela; ArgentinaFil: Mangold, Atilio Jose. Instituto Nacional de Tecnología Agropecuaria Eea, Rafaela; ArgentinaFil: Mastropaolo, Mariano. Instituto Nacional de Tecnología Agropecuaria Eea, Rafaela; ArgentinaFil: Casás, Gustavo. UNIVERSIDAD DE LA REPUBLICA (UDELAR); . Universidad de la República; UruguayFil: Guglielmone, Alberto Alejandro. Instituto Nacional de Tecnología Agropecuaria Eea, Rafaela; Argentin

Divergent environmental preferences and areas of sympatry of tick species in the Amblyomma cajennense complex (Ixodidae)

Four species of Neotropical ticks, Amblyomma mixtum, Amblyomma cajennense, Amblyomma tonelliae and Amblyomma sculptum (formerly included in the catch-all name A. cajennense), have an allopatric distribution in much of their range, with areas of parapatry for at least two of them. We inferred the abiotic niches of these organisms using coefficients of a harmonic regression of the temperature and the Normalized Difference Vegetation Index (NDVI, reflecting plant stress) from remotely sensed data from MODIS satellites with 0.05° spatial resolution. Combinations of coefficients describing the phenology of these two variables pointed to divergent niche preferences, compatible with previous events of vicariance among the species. Amblyomma cajennense has been recorded in areas with small variations in temperature and NDVI. The remaining species were recorded in areas with large variations. The maximum environmental niche overlap was ∼73.6% between A. mixtum and A. cajennense and 73.5% between A. tonelliae and A. sculptum. Projecting these inferences on the geographical space revealed probable areas of sympatry or parapatry between A. mixtum and A. cajennense or between A. tonelliae and A. sculptum, the latter of which was confirmed with field collections. The A. sculptum distribution overlaps with that of A. tonelliae in northern Argentina and Paraguay; parapatry occurs at one extreme of the conditions occupied by both species. Compared with areas of allopatry, sites with both species had consistently lower temperatures, except for 10–12 weeks during the summer, and higher NDVI values throughout the year. We hypothesise that the overlap between A. tonelliae and A. sculptum resulted from secondary contact between populations, with A. sculptum adapting to sites with high water availability to balance high summer temperatures. Additional surveys of the areas of spatial overlap among these species are necessary to elucidate the forces driving their evolution and their adaptation to the environment.Fil: Estrada Peña, Agustín. Universidad de Zaragoza; EspañaFil: Tarragona, Evelina Luisa. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Vesco, Umberto. Università di Torino; ItaliaFil: De Meneghi, Daniele. Università di Torino; ItaliaFil: Mastropaolo, Mariano. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Mangold, Atilio Jose. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Guglielmone, Alberto Alejandro. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Nava, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentin

Distribution and 16S rDNA sequences of Argas monachus (Acari: Argasidae), a soft tick parasite of Myiopsitta monachus (Aves: Psittacidae)

Specimens of Argas monachus Keirans et al. were collected from Myiopsitta monachus nests in 42 localities in Argentina and Paraguay from 2006 to 2010. A list of localities where this tick has been found is presented. 16S rDNA sequences of specimens of A. monachus from different localities were compared to confirm whether they belong to the same specific taxon. Argas monachus is present in the phytogeographic provinces of Chaco, Espinal, and Monte, but not in the Pampa (all from de Chaco Domain) where the host is well distributed. No differences were found among 16S rDNA sequences of geographically distant specimens. © 2011 Springer Science+Business Media B.V.Fil: Mastropaolo, Mariano. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela. Agencia de Extension Rural Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Turienzo, Paola Noemí. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Di Iorio, Osvaldo Rubén. Universidad de Buenos Aires; ArgentinaFil: Nava, Santiago. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Venzal, José Manuel. Universidad de la República; UruguayFil: Guglielmone, Alberto Alejandro. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela. Agencia de Extension Rural Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mangold, Atilio Jose. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela. Agencia de Extension Rural Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Rickettsia parkeri in Argentina

Clinical reports of an eschar-associated rickettsiosis in the Paraná River Delta of Argentina prompted an evaluation of Amblyomma triste ticks in this region. When evaluated by PCR, 17 (7.6%) of 223 questing adult A. triste ticks, collected from 2 sites in the lower Paraná River Delta, contained DNA of Rickettsia parkeri

Epidemiology of bovine babesiosis caused by Babesia bigemina (Smith y Kilborne, 1893) in Southwestern Chaco province

Babesia bigemina es uno de los agentes etiológicos de la babesiosis de los bovinos y en Argentina es transmitida solamente por ninfas y adultos de la garrapata Rhipicephalus (B.) microplus. Los objetivos de este trabajo fueron evaluar el estatus epidemiológico y factores asociados para B. bigemina en rodeos del sudoeste de la provincia del Chaco y evaluar la incidencia de infección y la proporción de garrapatas infectadas en dos establecimientos ganaderos (AT y VA) de la región. Se determinó que un 51% de los rodeos se encontraba en inestabilidad enzoótica, con riesgo de sufrir brotes de importancia económica. El estatus epidemiológico se asoció con la utilización de pasturas megatérmicas perennes. No se encontró relación entre el control de garrapatas y la transmisión de B. bigemina ni una relación espacial entre los campos con el mismo estatus epidemiológico, infiriéndose que los factores de manejo tendrían mas influencia que los geográficos en la epidemiología de la enfermedad en la región estudiada. La proporción de garrapatas infectadas con B. bigemina fue de 19,8 % para AT y 9,3 % para VA. Esto explicaría una mayor transmisión del parásito en AT con respecto a VA. Sin embargo la infección estuvo relacionada con la proporción de animales con presencia de garrapatas y no con la abundancia de garrapatas sobre los animales. Esto indicaría que la proporción de garrapatas infectadas no sería una limitante para la transmisión y que las situaciones de baja transmisión no se deberían a la presencia de pocas garrapatas infectadas ni de pocas garrapatas sobre los animales, sino a pocos animales con garrapatas sobretodo por efecto de una distribución agregada. Se infiere que la variable más relevante en la regulación de la dinámica de transmisión es la densidad de hospedadores, o carga instantánea.Babesia bigemina is one of the etiological agents of bovine babesiosis and in Argentina is transmitted only by nymphs and adults of the tick Rhipicephalus (B.) microplus. The objectives of this study were to evaluate the epidemiological status and associated factors for B. bigemina in cattle herds from south western Chaco province and to evaluate the incidence of infection and the proportion of infected ticks in two cattle farms (AT and VA) of the region. It was asserted that 51% of the herds were in a situation of enzootic instability, with risks of suffering outbreaks of economical importance. The epidemiological status was associated with the use of megathermal perennial pastures. Neither was determined a relationship between tick control and transmission of B. bigemina nor a spatial relationship between farms with the same epidemiological status, inferring from this that farm management factors are of greater influence on the epidemiology of the disease in the surveyed region than the geographical factors. The proportion of ticks infected with B. bigemina was 19.8% for AT and 9.3% for VA. This could explain a greater transmission of the parasite in AT compared to VA. The infection, however, was related to the proportion of animals with presence of ticks and not to the abundance of ticks on the animals. This could indicate that the proportion of infected ticks is not a limiting factor for transmission and that the situations of low transmission are not due to a low proportion of infected ticks and even not due to low ticks boundaries on the animals, but due to a low proportion of animals with ticks, specially because of an aggregated distribution. It is inferred that the most relevant variable in regulation of dynamics of transmission is the host density, or stock density.Facultad de Ciencias Veterinaria

Epidemiology of bovine babesiosis caused by Babesia bigemina (Smith y Kilborne, 1893) in Southwestern Chaco province

Babesia bigemina es uno de los agentes etiológicos de la babesiosis de los bovinos y en Argentina es transmitida solamente por ninfas y adultos de la garrapata Rhipicephalus (B.) microplus. Los objetivos de este trabajo fueron evaluar el estatus epidemiológico y factores asociados para B. bigemina en rodeos del sudoeste de la provincia del Chaco y evaluar la incidencia de infección y la proporción de garrapatas infectadas en dos establecimientos ganaderos (AT y VA) de la región. Se determinó que un 51% de los rodeos se encontraba en inestabilidad enzoótica, con riesgo de sufrir brotes de importancia económica. El estatus epidemiológico se asoció con la utilización de pasturas megatérmicas perennes. No se encontró relación entre el control de garrapatas y la transmisión de B. bigemina ni una relación espacial entre los campos con el mismo estatus epidemiológico, infiriéndose que los factores de manejo tendrían mas influencia que los geográficos en la epidemiología de la enfermedad en la región estudiada. La proporción de garrapatas infectadas con B. bigemina fue de 19,8 % para AT y 9,3 % para VA. Esto explicaría una mayor transmisión del parásito en AT con respecto a VA. Sin embargo la infección estuvo relacionada con la proporción de animales con presencia de garrapatas y no con la abundancia de garrapatas sobre los animales. Esto indicaría que la proporción de garrapatas infectadas no sería una limitante para la transmisión y que las situaciones de baja transmisión no se deberían a la presencia de pocas garrapatas infectadas ni de pocas garrapatas sobre los animales, sino a pocos animales con garrapatas sobretodo por efecto de una distribución agregada. Se infiere que la variable más relevante en la regulación de la dinámica de transmisión es la densidad de hospedadores, o carga instantánea.Babesia bigemina is one of the etiological agents of bovine babesiosis and in Argentina is transmitted only by nymphs and adults of the tick Rhipicephalus (B.) microplus. The objectives of this study were to evaluate the epidemiological status and associated factors for B. bigemina in cattle herds from south western Chaco province and to evaluate the incidence of infection and the proportion of infected ticks in two cattle farms (AT and VA) of the region. It was asserted that 51% of the herds were in a situation of enzootic instability, with risks of suffering outbreaks of economical importance. The epidemiological status was associated with the use of megathermal perennial pastures. Neither was determined a relationship between tick control and transmission of B. bigemina nor a spatial relationship between farms with the same epidemiological status, inferring from this that farm management factors are of greater influence on the epidemiology of the disease in the surveyed region than the geographical factors. The proportion of ticks infected with B. bigemina was 19.8% for AT and 9.3% for VA. This could explain a greater transmission of the parasite in AT compared to VA. The infection, however, was related to the proportion of animals with presence of ticks and not to the abundance of ticks on the animals. This could indicate that the proportion of infected ticks is not a limiting factor for transmission and that the situations of low transmission are not due to a low proportion of infected ticks and even not due to low ticks boundaries on the animals, but due to a low proportion of animals with ticks, specially because of an aggregated distribution. It is inferred that the most relevant variable in regulation of dynamics of transmission is the host density, or stock density.Facultad de Ciencias Veterinaria

Distribution and genetic variation of Amblyomma triste (Acari: Ixodidae) in Argentina

A study was conducted to investigate the distribution of Amblyomma triste in Argentina under the hypothesis that this tick prevails in riparian localities along the Paraná River and adjacent humid environments from 34°30′ S to 25°20′ S, approximately. Ticks were collected from mammals and vegetation in those environments from November 2008 to October 2012. Additionally, genetic variation was tested from Argentinean, Brazilian, Chilean, and Uruguayan populations of A. triste by comparing sequences of 16S rDNA mitochondrial gene. The hypothesis was not confirmed because A. triste were collected at 36°16′ S, well beyond the southern limit predicted, and the distribution along the banks of the Paraná River was not continuous. The northernmost population of A. triste within Argentina was found at 25°42′ S. Still undetermined abiotic factors and plant communities may play a role in modulating the abundance of A. triste because host availability does not appear to be a restriction factor. The genetic variation among A. triste populations from Argentina, Brazil, and Uruguay indicates that they belong to a unique taxon that is considered bona fide A. triste (type locality Montevideo, Uruguay) while it is unclear if the Chilean population of A. triste is conspecific with the other populations investigated in this study. It would be of importance to compare those genetically homogeneous populations with other populations of alleged A. triste, especially populations established in the Nearctic Zoogeographic Region in Mexico and USA.EEA RafaelaFil: Guglielmone, Alberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mastropaolo, Mariano. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Cátedra de Parasitología y Enfermedades Parasitarias; ArgentinaFil: Mangold, Atilio Jose. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Non-parasitic life cycle of the cattle tick Rhipicephalus (Boophilus) microplus in Panicum maximum pastures in northern Argentina

The aim of this work was to study the non-parasitic phase of the Rhipicephalus microplus life cycle in Panicum maximum grasses from northern Argentina, in order to provide ecological information for designing methods of tick control. Four localities were chosen as replicates. The biological parameters measured were proportion of females ovipositing, the pre-oviposition period, the proportion of egg clusters hatching, the incubation period of eggs, larval longevity, and the total non-parasitic period (time from the exposure of the female to the date of death of the last larva) (TNPP)). The following general trends were observed: I) a longer TNPP occurred when female ticks were exposed in mid- and late summer and early spring; II) the shortest TNPP occurred when female ticks were exposed from late winter to late spring; III) larvae that were active in early and mid-summer had the shortest longevity; IV) incubation periods of eggs, which originated from females exposed in late summer, early autumn and mid-spring, were longer than the incubation period of eggs produced by females exposed in late spring and early summer; V) eggs did not hatch when the engorged females were exposed in the pastures in mid- and late autumn and winter. The spelling period of the P. maximum grasses that is needed to ensure total control of R. microplus consists of 19–20 weeks if the spelling starts in late spring and early summer, and 27–28 weeks if the spelling begins in mid- and late summer or in autumn.Fil: Mastropaolo, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias; ArgentinaFil: Mangold, Atilio Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Guglielmone, Alberto Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Nava, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentin