Changes in thermal sensitivity of Rhinella arenarum tadpoles (Anura: Bufonidae) exposed to sublethal concentrations of different pesticide fractions (Lorsban® 75WG).

The intensive use of agrochemicals and the rapid increase of global temperatures have modified the thermal conditions of aquatic environments, thus increasing amphibians' vulnerability to global warming and positioning them at great risk. Commercial formulations of chlorpyrifos (COM) are the pesticides most widely used in agricultural activities, with a high toxic potential on amphibians. However, little is known about the separate effects of the active ingredient (CPF) and adjuvants (AD). We studied the thermal sensitivity at different concentrations and pesticide fractions in Rhinella arenarum tadpoles, on thermal tolerance limits (CTmax = Critical thermal maximum and CTmin = Critical thermal minimum), swimming speed (Ss), Optimum temperature (Top), and Thermal breadth 50 (B50). Our results demonstrate that the pesticide active ingredient, the adjuvants, and the commercial formulation of chlorpyrifos differentially impair the thermal sensitivity of R. arenarum tadpoles. The pesticide fractions affected the heat and the cold tolerance (CTmax and CTmin), depending on the concentrations they were exposed to. The locomotor performance (Ss, Top, and B50) of tadpoles also varied among fractions, treatments, and environmental temperatures. In the context of climate change, the outcomes presented are particularly relevant, as mean temperatures are increasing at unprecedented rates, which suggests that tadpoles inhabiting warming and polluted ponds are currently experiencing deleterious conditions. Considering that larval stages of amphibians are the most susceptible to changing environmental conditions and the alarming predictions about environmental temperatures in the future, it is likely that the synergism between high temperatures and pesticide exposure raise the threat of population deletions in the coming years.

Thermal sensitivity of Rhinella arenarum tadpole at low concentrations of dimethoate pesticides.

One of the main causes of contamination of aquatic environments, which affects biotic communities, is the use of pesticides in agricultural regions. Amphibians are considered good bio-indicators of aquatic pollution, because they are one of the most susceptible groups to pollution. Several studies suggest that both pollution and climate change produce synergistic effects in amphibians which amplify the toxicity afecting survival, and malformations with an increase in temperature. We studied the sensitivity of sublethal concentrations of dimethoate in Rhinella arenarum tadpoles on two fitness related thermal traits including locomotor swimming performance and thermal tolerance limits (CTmax = critical thermal maximum and CTmin = critical thermal minimum). The locomotor performance of R. arenarum tadpoles decreased with increasing sublethal dimethoate concentrations up to ∼60 % at intermediates dimethoate concentration. The tadpoles showed a tendency to decrease their tolerance to high temperatures (CTmax) with increasing dimethoate concentration around ∼0.5 °C, however no significant differences were found among treatments. Similarly, tadpoles showed decreases in their cold resistance (CTmin) with dimethoate concentrations, around 1 °C the high concentrations of dimethoate. The increase of atypical climatic events, such as heat waves may put R. arenarum tadpoles at greater risk when exposed to dimethoate. Our results show that the sublethal concentrations of the dimethoate pesticide may affect the fitness and survival of the larvae of R. arenarum in natural, and seminatural enviroments.

Testosterone is closely related to Leydig cell activity, environmental factors, and androgen receptor distribution in adult male lizards of Liolaemus cuyanus (Reptilia: Liolaemidae) during the reproductive cycle.

Testosterone, the primary sex hormone in male lizards, is closely linked to Leydig cell activity (the cells where steroidogenesis occurs) throughout the reproductive cycle, but testosterone action is related to androgen receptors (ARs) distribution in the seminiferous epithelium. In temperate zones, environmental factors detected through the hypothalamic-pituitary-gonadal axis, downregulate plasma testosterone, resulting in a seasonal reproductive cycle. The aim of this work is to study plasma testosterone in adult male lizards of Liolaemus cuyanus, an oviparous species, throughout its reproductive cycle and its relationship with Leydig cell histology, TotalLeydigCell/ActiveLeydigCell (TLC/ALC) ratio, environmental factors (temperature, relative humidity and solar irradiation) and ARs distribution in seminiferous epithelium. Specimens (N = 27) were captured (October to March) in a semi-arid zone (Valle de Matagusanos, San Juan, Argentina) and grouped into three relevant reproductive periods: pre-reproductive (PrR), reproductive (R), and post-reproductive (PsR). Significant differences in plasma testosterone were found among these periods, highest during R than in PsR. A significant positive correlation between plasma testosterone and TLC/ALC ratio was also observed. Plasma testosterone has a significant positive correlation only with solar irradiation, but not with the other variables. In PrR and R, ARs distribution was cytoplasmic and nuclear, shifting to only cytoplasmic in PsR. These results highlight the close correspondence between plasma testosterone, Leydig cell histology and activity, environmental factors, and ARs distribution, resulting in a synchronization that allows males of L. cuyanus to coordinate their reproductive cycle with the most favorable environmental conditions, probably for mating and birth of offspring.

Thermophilic response post feeding in Pleurodema nebulosum (Anura: Leptodactylidae) from Monte desert, Argentina.

We studied the thermophilic response to feeding of a typical desert adapted anuran from the Monte Desert. Our aim was to evaluate thermal changes in the selected body temperature of adult frogs of Pleurodema nebulosum, and measure the intestinal passage time, and food digestion. Our results show that after feeding, they selected higher micro-environmental temperatures ~ + 2 °C than frogs that remained starved. Pleurodema nebulosum would present a postprandial thermophilic response. The time of retention of food in the digestive tract was thermo-dependent, being lower in those individuals who were incubated at high temperatures (25 °C) compared to those subjected to lower temperatures (20 °C). Although we did not detect effects of temperature on digestive efficiency, the mass of faecal material indicates an increase at temperatures closer to the selected ones, suggesting that the defecation rate is influenced by temperature. Laiuoperinae frogs are characterized by explosive breeding behavior and fast growing rate. The digestive efficiency is essential for acquiring energy necessary for growth, reproduction and refuge-seeking, among others. In this framework, the differential selection of temperatures between moments of fasting and feeding allows the frogs to maintain a high digestive efficiency, maximizing the absorption of nutrients.

The body temperature of active desert anurans from hyper-arid environment of South America: The reliability of WorldClim for predicted body temperatures in anurans.

The temperature of anuran activity from arid regions have been poorly studied. In recent years, the emphasis was placed on predicting the impacts of global warming on the fauna of ectotherms in general. Many times future impacts are predicted based on global thermal information (macroscale) but not on an individual scale. We used literature data about body temperature in anurans that inhabit the desert region of the Northwest of Argentina to analyze the role of the elevation, eco-region and substrate temperature on the individual scale. Also, we evaluated the predictive capacity that global environmental variables obtained from WorldClim for this region, and compared them with those of local scale. Our results showed that the activity body temperature of the toads in the arid region of western Argentina strongly influenced by elevation and the substrate temperature on the individual scale. We observed that data of the global scale (WorldClim) can predict the body temperature of the studied amphibians, but with a deviation, not less than 8 °C. According to our results, it is evident that to making reliable predictions of how global warming impacts on amphibians in the region, the environmental temperature data need to be recorded at the local scale (operative temperatures).

Sublethal concentrations of chlorpyrifos induce changes in the thermal sensitivity and tolerance of anuran tadpoles in the toad Rhinella arenarum?

Amphibians are considered one of the groups most susceptible to chemical contamination, therefore are good bio-indicators of aquatic pollution. Synergistic effects of temperature and pesticides have been found in amphibians determining amplified toxicity effect on survival and malformations with increasing temperatures. We studied the sensitivity of sublethal concentrations of chlorpyrifos in Rhinella arenarum tadpoles over on two fitness related thermal traits: locomotor swimming performance and thermal tolerance limits (CTmax = critical thermal maximum and CTmin = critical thermal minimum). Our result shows a decrease in the locomotor performance of R. arenarum tadpoles with increasing sublethal chlorpyrifos concentrations. The experimental temperature increased locomotor performance but this being only significant for the control whereas tadpoles raised at any sublethal chlorpyrifos concentration did not increase their total swimming distance with temperature (Concentration × Temperature interaction, P < 0.019). Chlorpyrifos toxicity decreases maximum swimming distance but this reduction not compensated at high temperatures that do enhance swimming performance in the control treatment. On the other hand, higher chlorpyrifos sensitivity in CTmax than CTmin since tadpoles exposed to all polluted treatments exhibits a significant decline in CTmax but not in CTmin. Current global warming and the increase of atypical climatic events, such as heat waves may put at risk the larval chlorpyrifos polluted populations of R. arenarum. Our results show that the sublethal concentrations of the chlorpyrifos pesticide may affect the fitness and survival of the larvae of R. arenarum.

Toxicity of wine effluents and assessment of a depuration system for their control: assay with tadpoles of Rhinella arenarum (BUFONIDAE).

We evaluated the toxicity of the winery effluent and the efficiency of a symbiotic depuration system by means an experiment with Rhinella arenarum tadpoles. The studied effluent was taken from warehouses during the cleaning season. These effluents subsequently subjected to the purification treatment under evaluation. The effluent samples differentiated into two treatment levels: "raw" where the effluent was evaluated with field conditions and "treated" where the effluent was previously filtered with the symbiotic depuration system. The results of the bioassays compared with the physicochemical parameters determined in the effluent samples. The lethal response had a clear-cut correspondence with the effluent quality assessed utilizing physicochemical parameters. In all cases, dilution of the samples resulted in a significant reduction of their toxicity. It concluded that (a) winery effluents could be harmful to tadpoles of R. arenarum, (b) the symbiotic purification system used to treat wine effluents it would produce a significant reduction in the contaminant levels of the effluent. However, this reduction in contaminant levels does not provide sufficient safety for the release of the effluents into the environment.

Effect of salinity on locomotor performance and thermal extremes of metamorphic Andean Toads (Rhinella spinulosa) from Monte Desert, Argentina.

Rhinella spinulosa is distributed from Peru to Argentina (from 1200 to 5000 m elevation), inhabiting arid mountain valleys of the Andes, characterized by salty soils. The variations in soil salinity, caused by high evapotranspiration of water, can create an osmotic constraint and high thermal oscillations for metamorphsed Andean toad (R. spinulosa), affecting their thermoregulation and extreme thermal tolerances. We investigated the changes in thermal tolerance parameters (critical thermal maximum and crystallization temperature) of a population of metamorphosed R. spinulosa from the Monte Desert of San Juan, Argentina, under different substrate salinity conditions. Our results suggest that the locomotor performance of metamorphs of R. spinulosa is affected by increasing salinity concentrations in the environment where they develop. On the other hand, the thermal extremes of metamorphs of R. spinulosa also showed changes associated with different salinity conditions. According to other studies on different organisms, the increase of the osmolarity of the internal medium may increase the thermal tolerance of this species. More studies are needed to understand the thermo-osmolar adjustments of the metamorphs of toads to environmental variability.

Thermal ecology of the post-metamorphic Andean toad (Rhinella spinulosa) at elevation in the monte desert, Argentina.

Rhinella spinulosa is an anuran toad species distributed latitudinal and altitudinal (1200-5000m) from Peru to Argentina, inhabiting mountain valleys in the Andes. Considering the broad range of habitats where they live, it is important to understand the thermal physiological mechanisms, thermal tolerances and physiological adaptations for surviving in rigorous environments. We investigated the thermal parameters (field body temperature, selected body temperature, locomotor performance in field and laboratory conditions, and thermal extremes) during diurnal activity for a population of juvenile, post-metamorphosed toads (Rhinella spinulosa) from the Monte Desert of San Juan, Argentina. Post-metamorphic toads are active from approximately 1100-1900 (in contrast to nocturnal adult toads). Our findings show that these toads have a wide thermal tolerance range, ranging from a critical thermal maximum of 36.9°C to crystallization temperatures below 0°C. During their active period, toads always showed suboptimal thermal conditions for locomotion. Despite the suboptimal condition for the locomotion, diurnal activity is likely to confer thermal advantages, allowing them to search for food and increase digestion and growth rates. We also found that the toads are capable of super-cooling, which prevents mortality from freezing when the environmental temperatures drop below 0°C. The environmental temperatures are below zero at night, when toads are inactive and take refuge under rocks. In summary, this toad population demonstrates high thermal plasticity, as shown by a relatively high level of activity sustained over a wide range of ambient temperature (~35°C). These thermal adaptations allow this species of juvenile toads to inhabit a wide range of altitudes and latitudes.

Variation of thermal parameters in two different color morphs of a diurnal poison toad, Melanophryniscus rubriventris (Anura: Bufonidae).

We study the variation in thermal parameters in two contrasting populations Yungas Redbelly Toads (Melanophryniscus rubriventris) with different discrete color phenotypes comparing field body temperatures, critical thermal maximum and heating rates. We found significant differences in field body temperatures of the different morphs. Temperatures were higher in toads with a high extent of dorsal melanization. No variation was registered in operative temperatures between the study locations at the moment of capture and processing. Critical thermal maximum of toads was positively related with the extent of dorsal melanization. Furthermore, we founded significant differences in heating rates between morphs, where individuals with a high extent of dorsal melanization showed greater heating rates than toads with lower dorsal melanization. The color pattern-thermal parameter relationship observed may influence the activity patterns and body size of individuals. Body temperature is a modulator of physiological and behavioral functions in amphibians, influencing daily and seasonal activity, locomotor performance, digestion rate and growth rate. It is possible that some growth constraints may arise due to the relationship of color pattern-metabolism allowing different morphs to attain similar sizes at different locations instead of body-size clines.

Falcaustra sanjuanensis sp. nov. (Nematoda: Kathlaniidae) from Odontophrynus cf. barrioi (Anura: Cycloramphidae) from Argentina.

Here, we describe a new kathlaniid nematode, Falcaustra sanjuanensis sp. nov., from the large intestine of Odontophrynus cf. barrioi (Anura: Cycloramphidae), from San Juan Province, Argentina. The new species belongs to the Falcaustra group that possesses a pseudosucker. It resembles F. andrias in the distribution pattern of caudal papillae (six precloacal, four adcloacal, 12 postcloacal, one unpaired median anterior to the cloaca) but differs from F. andrias in the following characters: the longer size of males and females (11.17-13.45 mm and 10.1-15.5 mm, respectively); the longer size and form of the gubernaculum (0.17-0.23 mm, triangular form); the arrangement of postcloacal papillae (three pairs on the ventral side, two pairs on the lateral side, one pair on the subventral side) and unpaired papilla anterior to the cloaca located on the protuberance. The species description is based on light microscopy and scanning electron microscopy (SEM). Falcaustra sanjuanensis sp. nov. represents the 12th Neotropical species assigned to the genus. Also, we added a key to Neotropical species of Falcaustra.

Ampliación de la distribución de Sephanoides sephaniodes (Trochilidae: Aves) en Argentina

El presente trabajo reporta la ampliación de la distribución de Sephanoides sephaniodes hacia el centro-oeste de Argentina. Se analizan posibles causas de la dispersión y consecuencias ecológicas de la misma.

The present work report the expansion of the distribution of Sephanoides sephaniodes toward the west-central of Argentina. It discusses possible causes of dispersion and ecological consequences of them.

Variation in the thermal parameters of Odontophrynus occidentalis in the Monte desert, Argentina: response to the environmental constraints.

We studied the variation of thermal parameters of Odontophrynus occidentalis between season (wet and dry) in the Monte desert (Argentina). We measured body temperatures, microhabitat temperatures, and operative temperatures; while in the laboratory, we measured the selected body temperatures. Our results show a change in the thermal parameters of O. occidentalis that is related to environmental constraints of their thermal niche. Environmental thermal constraints are present in both seasons (dry and wet), showing variations in thermal parameters studied. Apparently imposed environmental restrictions, the toads in nature always show body temperatures below the set point. Acclimatization is an advantage for toads because it allows them to bring more frequent body temperatures to the set point. The selected body temperature has seasonal intraindividual variability. These variations can be due to thermo-sensitivity of toads and life histories of individuals that limits their allocation and acquisition of resources. Possibly the range of variation found in selected body temperature is a consequence of the thermal environmental variation along the year. These variations of thermal parameters are commonly found in deserts and thermal bodies of nocturnal ectotherms. The plasticity of selected body temperature allows O. occidentales to have longer periods of activity for foraging and reproduction, while maintaining reasonable high performance at different temperatures. The plasticity in seasonal variation of the thermal parameters has been poorly studied, and is greatly advantageous to desert species during changes in both seasonal and daily temperature, as these environments are known for their high environmental variability.

Thermal parameters changes in males of Rhinella arenarum (Anura:Bufonidae) related to reproductive periods.

The regulation of body temperature in ectotherms has a major impact in their physiological and behavioral processes. Observing changes in thermal parameters related with reproduction allows us to better understand how Rhinella arenarum optimizes a thermal resource. The aim of this study was to compare the thermal parameters of this species between breeding and non-breeding periods. In the field, we recorded the body temperature from captured animals, the air temperature, and the temperature of the substrate. In the laboratory, we measured the temperature R. arenarum selected on a thermal gradient and the critical extreme temperatures. The results of our study show variations in thermal parameters between the two situations studied. This species makes efficient use of thermal resources during the breeding period by basking to significantly increase body temperature. Because calling is energetically costly for males, this behavior results in increased efficiency to callers during the breeding period.

Thermal parameters changes in males of Rhinella arenarum (Anura:Bufonidae) related to reproductive periods

The regulation of body temperature in ectotherms has a major impact in their physiological and behavioral processes. Observing changes in thermal parameters related with reproduction allows us to better understand how Rhinella arenarum optimizes a thermal resource. The aim of this study was to compare the thermal parameters of this species between breeding and non-breeding periods. In the field, we recorded the body temperature from captured animals, the air temperature, and the temperature of the substrate. In the laboratory, we measured the temperature R. arenarum selected on a thermal gradient and the critical extreme temperatures. The results of our study show variations in thermal parameters between the two situations studied. This species makes efficient use of thermal resources during the breeding period by basking to significantly increase body temperature. Because calling is energetically costly for males, this behavior results in increased efficiency to callers during the breeding period. Rev. Biol. Trop. 59 (1): 347-353. Epub 2011 March 01.

La regulación de la temperatura en ectotérmos tiene gran importancia en los procesos fisiológicos y comportamentales. Los cambios en los parámetros térmicos relacionados con la reproducción nos permiten entender de qué manera Rhinella arenarum optimiza el recurso térmico. El objetivo del presente trabajo fue comparar los parámetros térmicos de la especie entre el periodo reproductivo y no reproductivo. En el campo se registraron la temperatura corporal de los animales capturados, la temperatura del aire y del sustrato. Además, en laboratorio se registro la temperatura selecta en un gradiente térmico. Como así también las temperaturas criticas máxima y mínima. Los resultados de nuestro estudio muestran variaciones de los parámetros térmicos entre ambas situaciones estudiadas. Aparentemente esta especie hace un uso eficiente del recurso térmico durante el periodo reproductivo ya que el basking le permite aumentar considerablemente la temperatura corporal, probablemente este comportamiento esté relacionado con el aumento de la eficacia para emitir el canto durante el periodo de reproducción ya que el mismo es energéticamente costoso para los machos.

A prospective study demonstrating the effect of 5% povidone-iodine application for anterior segment intraocular surgery in Paraguay.

PURPOSE: To determine the conjunctival bacterial flora in cataract surgery patients and the effect of presurgical irrigation with 5% povidone-iodine solution. METHODS: Three samples from the inferior conjunctival fornix of the eye to be operated were obtained at baseline before washing (T0) with 10 ml 5% povidone-iodine solution, immediately after washing (T1), and upon completion of surgery (T2). Bacteria from the samples were inoculated in blood agar, chocolate agar, and thioglycolate broth. RESULTS: A total of 221 patients (n=224 eyes) with a mean age of 67 +/- 13 years were included in the study. Bacteria from the (T0) samples were successfully grown in 73.2% of the thioglycolate agars, 21.0% of the blood agars, and 19.2% of the chocolate agars. Compared with T1 samples, the use of povidone-iodine wash translated into a 60.8% reduction (from 73.2% to 12.5%) in colonization of the conjunctiva (p<0.001), while no significant difference was found between the T1 and T2 samples. CONCLUSION: Conjunctival irrigation with a 5% povidone-iodine solution effectively reduces conjunctival flora and is therefore strongly recommended as a means of preventing postsurgical endophthalmitis following cataract surgery.

First record of partial albinism and scoliosis in Odontophrynus occidentalis tadpoles (Anura: Cycloramphidae)

Albinism has been widely reported for diverse group of vertebrates. However, scoliosis is a rare abnormality. In this work, the first record of partial albinism and scoliosis case in tadpole of the frog Odontophrynus occidentalis is being presented. The individual was captured in Quebrada de las Flores, Sierra Pie de Palo, Caucete Department, San Juan Province, Argentina.

Characteristics of the corneal endothelium and pseudoexfoliation syndrome in patients with senile cataract.

BACKGROUND: The characteristics of the corneal endothelium in patients with/without pseudoexfoliation syndrome (PEX) with senile cataract in Paraguay are unknown. METHODS: Endothelial density, mean coefficient of variation (%) in cell size and mean cell hexagonality (%) were measured using automated specular microscopy. Multivariate general linear model analysis was used to determine the effect of age, gender and PEX on endothelial characteristics. Analysis of variance tests analysed the effect of age on endothelial variables without regard to PEX status. Categories of <2000 and > or =2000 cells/mm(2) were compared in the presence/absence of PEX using age as covariate to calculate odds ratios for corneal decompensation. RESULTS: Out of 468 eligible patients, 51 were excluded. Sixty-one patients had PEX. Unadjusted mean endothelial cell density was 2451 cells/mm(2); cell size coefficient of variation was 34.3; and the mean percentage of hexagonal cells was 57.7. Adjusting for age, only the mean difference between the groups with and without PEX for endothelial cell density was significant (PEX = 2315, no PEX = 2482, P = 0.002). Of the total study population, at-risk endothelial cell densities were found in 46 eyes (11%); and 13 (28%) of those were found to have PEX. When PEX was present, the calculated odds ratio for corneal decompensation following surgery was 1.90 after adjustment for age. CONCLUSIONS: Endothelial cell density data were consistent with published literature. Because Paraguay has a high prevalent of PEX, it is suggested that specular microscopy screening be carried out for all patients scheduled for intraocular surgery where feasible.

A prospective study demonstrating the effect of 5 percent povidone-iodine application for anterior segment intraocular surgery in Paraguay / Estudio prospectivo demostrando el efecto de la instilación de yodo povidona al 5 por ciento previo a cirugía de segmento anterior en Paraguay

PURPOSE: To determine the conjunctival bacterial flora in cataract surgery patients and the effect of presurgical irrigation with 5 percent povidone-iodine solution. METHODS: Three samples from the inferior conjunctival fornix of the eye to be operated were obtained at baseline before washing (T0) with 10 ml 5 percent povidone-iodine solution, immediately after washing (T1), and upon completion of surgery (T2). Bacteria from the samples were inoculated in blood agar, chocolate agar, and thioglycolate broth. RESULTS: A total of 221 patients (n=224 eyes) with a mean age of 67 ± 13 years were included in the study. Bacteria from the (T0) samples were successfully grown in 73.2 percent of the thioglycolate agars, 21.0 percent of the blood agars, and 19.2 percent of the chocolate agars. Compared with T1 samples, the use of povidone-iodine wash translated into a 60.8 percent reduction (from 73.2 percent to 12.5 percent) in colonization of the conjunctiva (p<0.001), while no significant difference was found between the T1 and T2 samples. Conclusion: Conjunctival irrigation with a 5 percent povidone-iodine solution effectively reduces conjunctival flora and is therefore strongly recommended as a means of preventing postsurgical endophthalmitis following cataract surgery.

OBJETIVO: Determinar la flora bacteriana de la conjuntiva en los pacientes a ser sometidos a cirugía de catarata y el efecto del lavado prequirúrgico con yodo povidona al 5 por ciento sobre dichos microorganismos. MÉTODOS: Se tomaron 3 muestras del fondo de saco conjuntival del ojo a ser operado de catarata antes (T0) de la irrigación de la conjuntiva con 10 ml de yodo povidona al 5 por ciento, como control, inmediatamente después (T1) y al término de la cirugía (T2). Se realizaron cultivos en agar sangre, agar chocolate y en caldo de tioglicolato. RESULTADOS: Se incluyeron en el estudio 221 pacientes (n=24 ojos) con un promedio de edad de 67 ± 13 años. El porcentaje de crecimiento bacteriano en (T0) fue de 73,2 por ciento en tioglicolato, 21 por ciento en agar sangre y 19,2 por ciento en agar chocolate. Al compararlo con (T1) el efecto de la yodo povidona se tradujo en una reducción del 60,8 por ciento (de 73,2 por ciento a 12,5 por ciento) en la colonización conjuntival (p<0.001). Entre las muestras de los tiempos T1 y T2 no hubo diferencia significativa en cuanto al crecimiento bacteriano. CONCLUSIÓN: El lavado conjuntival con yodo povidona al 5 por ciento reduce de forma efectiva la flora conjuntival por lo cual se recomienda fuertemente como método preoperatorio, como una de las medidas preventivas de la endoftalmitis posquirúrgica en cirugías de catarata.

Hábitos alimentarios de infantiles de Pleurodema nebulosum (Anura: Leptodactylidae), en Matagusanos, San Juan, Argentina / Alimentary habits of infantile Pleurodema nebulosum (Anura: Leptodactylidae), in Matagusanos, San Juan, Argentina

Los hábitos alimentarios de Pleurodema nebulosum en el oeste de Argentina son desconocidos. El objetivo de este trabajo es analizar la dieta de una población de infantiles de P. nebulosum. Se analizaron 34 estómagos, se clasificaron taxonómicamente sus presas y se midieron (ancho y largo), se calculó su volumen con la fórmula de la esfera elipsoide, se estimó además la frecuencia de ocurrencia y abundancia. Los IRI más importantes fueron: Hemiptera (1867), Hymenoptera (hormigas) (1431), Coleoptera (127), entre otros. Las presas que presentaron mayor porcentaje de frecuencia fueron los Hymenoptera (48,5 por ciento), Hemiptera (26,9 por ciento) y Coleoptera (10,8 por ciento). El valor de diversidad media fue de 0.19 (SD=0,2) y la amplitud del nicho trófico fue de 3,17. Este valor indicaría una posible especialización y considerando la baja diversidad encontrada, podría estar reflejando la escasa disponibilidad de presas en ese momento.

The alimentary habits of Pleurodema nebulosum in the west of Argentina are unknown. The objective in this work was to analyze the diet of a population of infantile of P. nebulosum. We analyze 34 stomachs, the preys were classified and measured (wide and long), and their volumes were estimated with the sphere ellipsoid. It was considered the occurrence frequency and the abundance. The IRI most important were: Hemiptera (1867), Hymenoptera (1431), Coleoptera (127), among others. The preys with highest presence were the Hymenoptera (48,5 per cent), Hemiptera (26,9 per cent) y Coleoptera (10,8 per cent). The value of mean diversity was of 0,19 (SD= 0,2) and the width of trophic niche was of 3,17; it could be indicate a possible specialization. But, in considering the low diversity values, it could be for the scarce readiness of preys in that moment too.