Gastrointestinal nematodes and mineral deficiencies in yearling cattle in Santiago del Estero, northern Argentina.

The aims were to study the epidemiology and the effect of gastrointestinal nematodes (GINs) on yearling cattle in a semiarid region in Argentina and to evaluate the mineral serum levels. Ten- to twelve-month-old calves were monitored between November and April 2019. Animals were divided into three groups: untreated control (CONG; n = 20); group treated with moxidectin (MXD, 200 µg/kg) every 30-40 days (MXDG; n = 20); group equally MXD treated and mineral supplementation administered in November and January (MMG; n = 20). Individual GIN egg counts (epg) and fecal cultures were made every 30-40 days. Animal live weight gain was determined. On 7-11-18, 25-1-19, and 3-4-19, serum levels of Se, Cu, Zn, Mg, and Ca were determined by atom absorption spectrophotometry. At the start of the trial, epg values were low (x̄ = 5.5), which increased only in CONG towards the end of the assay (x̄ = 229). In both GMXD and MMG, epg remained very low (x̄ = 4.1). Cooperia spp. (81%) prevailed over Haemonchus spp. (9%) and Oesophagostomum spp. (9%). Deficiency of Se ranged between marginal and important, except for MMG, although mean values were always below normal. Cu was marginally deficient in CONG and MXDG on the first two sampling dates, whereas MMG had normal values after treatment. Mg had low values in the three groups (x̄ = 1.5 mg/dl), whereas Ca and Zn exhibited normal values. Live weight gain (LWG) was higher in MMG than in MXDG, with significant differences (p < 0.05) by mid-January and then, when epg increased, dewormed groups showed higher LWG (p < 0.034) than CONG. A negative effect of GINs on LWG was observed, as well as low to marginal levels of Se, Cu, and Mg.

Triatominae of the semi-arid Chaco in central Argentina.

The epidemiological scenario in central Argentinian Chaco region shows persistence of Triatoma infestans domestic populations in endemic areas, with control interventions historically affected by the economic instability of the region. Considering this situation, we aimed to (i) update the information regarding to the diversity of triatomines present in domestic, peridomestic and sylvatic environments in departments historically endemic of the Chaco region, (ii) to report the occurrence of secondary vectors of Chagas disease invading domestic environments and (iii) to discuss the possible sources of dispersal of these sylvatic species towards anthropic habitats. Between November 2017 and March 2020, we visited fourteen rural communities of northwest Córdoba province (central Argentina). Entomological data were collected through community vector surveillance in domiciles, active search in peridomiciles and the use of light and yeast traps in sylvatic environments. Seven Triatominae species were captured invading domiciles (T. guasayana, T. garciabesi, T. platensis, T. delpontei, T. breyeri, Panstrongylus guentheri and T. infestans). T. guasayana and T. garciabesi were the species with the highest number of captures. The 32% of the peridomiciles registered infestation with T. infestans (n â€‹= 355), mostly in chicken coops and goat pens. In sylvatic environments, T. garciabesi, T. guasayana, T. infestans and P. guentheri were collected. Only one adult specimen of T. infestans was positive for the presence of Trypanosoma cruzi. Our results suggest that the persistence of T. infestans populations in peridomiciles continues to be a serious challenge for control programs, whereas the finding of secondary vectors of Chagas disease actively invading domiciles emphasizes the need to implement new strategies for entomological surveillance.

Spatial analyzes of triatomine infestation indices and their association to the actions of a Chagas disease program and environmental variables during a 5-year intervention period.

Vector control of Chagas disease in the past decades has been mainly based on chemical control. Fundación Mundo Sano is implementing an Integral Chagas Program in a rural area of the Argentinean Gran Chaco Region since 2002. The objective of this study was to analyze both, temporal and spatial variation of infestation indices and their relation to the actions of the Program and environmental variables as land and vegetation cover changes, during a 5 year intervention period (2010-2014). Triatoma infestans infestation data from five rural localities from the Province of Santiago del Estero (Argentina) was analyzed in order to detect spatial aggregation. Differences in control effectiveness were observed between the peridomicile and intradomicile: infestation indices were higher in the peridomicile, recurrent infestation was present only in the peridomicile while low level infestation clusters were absent in the peridomicile. Cluster zones with low intradomestic infestation had larger proportions of bare soil and thin vegetation. In contrast, cluster zones with high intradomestic infestation had higher forest vegetation proportions and smaller cultivated area proportions. Spatial statistics analysis detected differences in cluster patterns between intra and peridomestic infestation suggesting that control actions should be based on geographical areas and not on political units. This work brings together different approaches to analyze infestation levels at the fine spatial scale, which could be used as a base for risk spatial stratification.

Epidemiología y efectos de los nematodes gastrointestinales en la recría bovina en el Chaco semiárido salteño

El objetivo del presente trabajo fue estudiar la epidemiología y el efecto de los nematodes gastrointestinales (NGI) en la recría bovina en la región del chaco semiárido de Salta. Desde marzo 2016 a febrero 2017 se formaron tres grupos de 20 terneras de recría: GMXD tratamiento cada 45 días con moxidectina (200 μg/kg), GIVM 1 solo tratamiento al inicio del ensayo con ivermectina 3,15% LA (630 μg/kg) y GCON control sin tratamiento. Cada 45 días se realizaron conteos de huevos (hpg) de nematodes y coprocultivos y se registró la ganancia de peso vivo (GPV). Al inicio los hpg fueron bajos (𝑥̅=102±77) elevándose en el GCON hacia mediados del invierno (𝑥̅ =1049±1040), para luego descender hacia el final del ensayo, luego de un pico a mediados de la primavera (𝑥̅ =667±928). Los hpg del GIVM mostraron solo un descenso parcial (37,3%) postratamiento y el GMXD siempre tuvo valores de hpg muy bajos, mostrando la eficacia de la moxidectina. Los géneros de nematodes predominantes fueron Haemonchus (47,1%) y Cooperia (45,9%). El efecto de los tratamientos se evidenció desde fines de otoño, mostrando el GMXD una mayor GPV (p<0,04) al final del invierno, comparado con los otros dos grupos. Al final del ensayo, las GPV totales del GMXD (146,5 kg) fueron significativamente (p<0,008) mayores que las del GIVM (111,0 kg) y del GCON (105,2 kg). Estos resultados muestran un pico del hpg a mediados de invierno, a Haemonchus y Cooperia como géneros predominantes y un efecto negativo en la GPV de la recría.

The aim of this study was to determine the epidemiology and the effects of gastrointestinal nematodes (GIN) on beef cattle heifers in the Chaco Semiarid region of Salta, Northwestern Argentina. In March 2016 sixty heifer calves were divided in three groups of twenty each: MXDG, calves treated with moxidectin (200 μg/kg) every 45 days, IVMG: calves treated once at the beginning of the trial with ivermectin LA (630 μg/kg) and CONG: untreated control calves. Faecal egg counts (FEC) and faecal cultures were performed every 45 days. Live weight gain (LWG) was recorded at each sampling time. The average FEC at the beginning of the trial was low (𝑥 ̅=102±77) for all groups. For the CONG the FEC peaked towards mid-winter (𝑥̅ =1049±1040), and mid-spring (𝑥̅ =667±928) and to decrease toward the end of the trial. FEC for IVMG only decreases partially (37.3%) post-treatment, while for MXDG showed always negligible values. The predominant genera were Haemonchus (47.1%) and Cooperia (45.9%). The moxidectin treatment effect was evident from late autumn onwards, the MXDG showed significant (p<0.04) higher LWG than the other two groups in late winter. At the end of the trial, the MXDG average total LWG (146.5 kg) was significantly (p<0.008) higher than those of IVMG (111.0 kg) and CONG (105.2 kg). The results of this study show a mid-winter peak in FEC, Haemonchus and Cooperia as predominant worms and a negative effect of GIN on beef heifer calves LWG.

Thermoconformity strategy in the freshwater turtle Hydromedusa tectifera (Testudines, Chelidae) in its southern distribution area.

Ectotherm species are not capable of generating metabolic heat; therefore, they present different strategies for regulating their body temperatures, ranging from a precise degree of thermoregulation to a passive thermoconformity with ambient temperatures. In reptiles, aerial basking is the most common mechanism for gaining heat. However, among aquatic reptiles, such as freshwater turtles, aquatic basking is also frequent. Hydromedusa tectifera is a turtle of exclusively aquatic and nocturnal habits widely distributed in South America. We studied the relationship between body temperature (Tb) of H. tectifera and its habitat, and explored the effects of sex, life stage and body size and mass on Tb. Fieldwork was conducted in two streams of a mountain area of central Argentina. We recorded cloacal temperature, size and mass of 84 turtles. We also determined individuals' sex and life stage (adult/juvenile). Regarding ambient temperatures, we measured water temperature on the surface (Tsurf) and at depth of turtle capture (Tdepth) and air temperature. Mean Tb was 18.58°C (Min = 10.20°C; Max = 25.70°C). Tsurf and Tdepth were highly correlated. Multi-model analysis using Akaike criterion indicated that Tb was strongly associated with water temperature, whereas air temperature and body size and mass did not show a significant effect. There was also no effect of turtle sex or life stage on Tb. Our results indicate that H. tectifera is a thermoconformer and eurythermal species. A nocturnal pattern of activity and a fully aquatic lifestyle are suggested as determinant factors.

Cambios anatómicos en raíces e hipocótilos de plántulas de Prosopis ruscifolia (Fabaceae) sometidas a estrés salino / Anatomical changes in roots and hypocotyls of Prosopis ruscifolia (Fabaceae) seedlings exposed to saline stress

ResumenProsopis ruscifolia es una especie arbórea pionera en áreas inundadas o salinas. El objetivo de este trabajo fue determinar cambios anatómicos en raíces e hipocótilos de plántulas de P. ruscifolia sometidas a estrés salino, bajo condiciones controladas. Las semillas se recolectaron en bosques nativos de la Región Chaqueña Occidental de Argentina. Las semillas se sembraron sobre toallas de papel humedecidas con soluciones salinas de 100, 200 y 300 mM de NaCl y un control humedecido con agua destilada. Se sembraron cuatro repeticiones de 50 semillas cada una, correspondientes a cada tratamiento, se ubicaron en cajas plásticas herméticas dentro de cámara de siembra a 27 ºC y con fotoperíodo de 12 horas. Doce días después de la siembra, se extrajeron plántulas para estudios anatómicos. Se estudiaron 35 plántulas correspondientes a cada tratamiento. Se midieron en raíces e hipocótilos las siguientes variables anatómicas: diámetro de la raíz principal e hipocótilo (µm), espesor de la corteza (µm), número de estratos celulares en la corteza, diámetro del cilindro central (µm), diámetro de la médula (µm), número de estratos celulares en el periciclo y diámetro tangencial de los vasos (µm). Se realizó ANOVA con diámetro de la raíz o hipocótilo como variable dependiente y espesor de la corteza, número de estratos celulares en la corteza, diámetro del cilindro central, diámetro de la médula, número de estratos celulares en el periciclo, diámetro tangencial de los vasos y concentración salina como variables independientes. El diámetro de la raíz disminuyó significativamente con el aumento de la concentración salina (P < 0.0001). El espesor de la corteza redujo su espesor a 100 mM (P < 0.0001) e incrementó el número de estratos celulares que la componen (P < 0.0002). El diámetro del cilindro central se redujo a la concentración salina de 100 mM (P < 0.0001) y el diámetro de la médula y el número de estratos celulares del periciclo (P < 0.0003) disminuyó progresivamente hasta 300 mM. El diámetro tangencial de los vasos (P < 0.0001) se redujo recién a 300 mM de NaCl. Estos cambios anatómicos podrían estar relacionados con la alteración de la expansión y división celular causada por la salinidad y comprometer la formación de raíces laterales y el almacenamiento de reservas. Los hipocótilos no mostraron cambios anatómicos significativos en respuesta al incremento en la salinidad, con excepción de la variación en la posición de estomas y un incremento en el espesor de la hipodermis. Estos cambios parecen indicar el estrés hídrico impuesto por el bajo potencial osmótico causado por las sales. Las plántulas de P. ruscifolia experimentaron cambios anatómicos en respuesta a las concentraciones salinas analizadas, en rasgos vinculados al almacenamiento de reservas, a la absorción y la conducción de agua y la formación de raíces laterales.

Abstract:Prosopis ruscifolia is a pioneer tree species in flooding or saline areas. The aim of this work was to assess anatomical changes in roots and hypocotyls of P. ruscifolia seedlings induced to saline stress under controlled conditions. Seeds, collected in natural forests of Western Chaco region in Argentina, were sown on paper towels moisturized with saline solutions of 100, 200 and 300 mM of NaCl, and a control group with distilled water. Four repetitions of 50 seeds per treatment were sown, located in hermetic polystyrene boxes, and included in a seeding chamber, at 27 ºC and 12 hours photoperiod. Were studied 35 seedlings from each saline concentration; these seedlings were processed 12 days after sown to obtain microscopic samples. The anatomical variables measured in roots and hypocotyls were the following: main root diameter (µm), bark thickness (µm), number of cell strata in bark, central cylinder diameter (µm), pith diameter (µm), number of cell strata in the pericycle and the tangential diameter of vessels (µm). ANOVA analysis were performed with hypocotyl and root diameters as the dependent variable, and bark thickness (µm), number of cell strata in the bark, the central cylinder diameter (µm), the pith diameter (µm), number of cell strata in the pericycle, the tangential diameter of vessels and the saline concentration as independent variables. Results showed that the root diameter decreased with increasing saline concentrations (P < 0.0001). The bark thickness decreased at 100 mM (P < 0.0001) and the number of cell strata of bark increased to 300 mM (P < 0.0002). The central cylinder diameter decreased at 100 mM saline concentration (P < 0.0001) and the number of cell strata of the pericycle and the pith diameter reduced progressively until 300 mM. The tangential diameter of vessels decreased at 300 mM. These anatomical changes suggested alterations in the expansion and cell division caused by the salinity, and could limit lateral roots formation and reserves storage. Hypocotyls did not show significant anatomical changes in response to increasing salinity, with exception of stomata position and an increase of the hypodermis thickness. These changes indicated that the water stress imposed by low osmotic potential is caused by increasing saline concentration. The seedlings of P. ruscifolia experienced anatomical changes in response to tested saline concentrations in traits related to reserve storage, the absorption and conduction of water, and lateral roots formation. Rev. Biol. Trop. 64 (3): 1007-1017. Epub 2016 September 01.

Hongos geofílicos en la zona occidental de la región chaqueña (Argentina) / Geophilic fungi in western zone of Chaco Region, Argentina

Mediante las técnicas de Orr y de dilución, se estudiaron muestras de tierra de la zona occidental de la región chaqueña recogidas durante las estaciones de invierno y verano del año 2006. Mediante el anzuelo queratínico se aislaron 22 géneros y 25 especies fúngicas. Los Onygenales estuvieron representados con sólo 8 géneros, principalmente Chrysosporium indicum, Aphanoascus fulvescens y Myceliophthora vellerea, mientras en los no Onigenales, destacan: Paecilomyces lilacinus y Aspergillus fumigatus. En las muestras procesadas por dilución en PDA, se obtuvieron 24 géneros y 43 especies. Entre éstas, el género más frecuente y con mayor diversidad fue Aspergillus, siendo A. fumigatus la especie más representada, siguiendo en importancia los micelios hialinos y dematiáceos sin fructificar, los Penicillium del sub género Biverticillium y los Trichoderma de la sección Trichoderma. Se destaca la presencia de Corynascus verrucosus y C. setosus. Con ambas técnicas no se obtuvieron diferencias significativas respecto del número total de aislamientos entre invierno y verano.

Soil samples from the western zone of Chaco Region and collected during winter and summer of 2006 were studied by means of Orr and dilution techniques. Twenty two genera and 25 fungal species resulted with the use of the keratinic bait. Onygenales were represented by only 8 genera, mainly Chrysosporium indicum, Aphanoascus fulvescens and Myceliophtora vellerea, while Paecilomyces lilacinus and Aspergillus fumigates were present in the not Onygenales group. In samples processed by PDA dilution, 23 genera and 43 species were obtained. Among these, Aspergillus was the most frequent genus and which showed the highest diversity, being A. fumigatus the highest represented species, followed in importance by fructification-free hyaline and dematiaceous mycelia, Penicillium of the sub genus Biverticillium and Trichoderma from the Trichoderma section. The presence of Corynascus verrucosus and C. setosus is also pointed out. There were no significant differences detected under both techniques as regards the overall number of isolations within winter and summer.