Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Rhipicephalus microplus, cattle common tick, transmits pathogens that affect the livestock production in tropical areas. For its control, pyrethroid compounds have been used whose inappropriate use has generated resistance in this tick. The study of the mechanisms of resistance to pyrethroids in R. microplus has shown the presence of mutations in genes related to its effect, either of enzymes that inactivate the compound or the sodium channels, the acaricide's target site. In Colombia, the first phase of the present project found a mutation in a hydrolyzing esterase in field populations of R. microplus resistant to pyrethroids. As it has been demonstrated that the resistance to chemicals in this tick is multigenic, in its second phase the project has as main objective to detect a polymorphism at position 2134 of the sodium channel gene. This mutation sustitutes a thymine for an adenine, T2134A, and has been previously related in other countries with pyrethroids resistance in carriers. For this, 182 R. microplus ticks were collected in two farms with history of resistance to this type of acaricides and they were subjected to the engorged female tick immersion test in a cypermethrin solution prepared at the recommended dose for field use obtaining six susceptible individuals, 92 resistant and 84 moderately resistant. DNA was extracted from all specimens by the phenol-chloroform method and was processed by conventional PCR using specific allele primers to amplify a segment of the IIIS6 domain of the sodium channel gene. The resulting amplicons were detected by electrophoresis in 2% agarose gels stained with GelRed® and visualized with ultraviolet light. In the same way, the sequencing of 20 samples obteined from the three susceptible, moderately resistant and resistant phenotypes was carried out and the resulting sequences were aligned through the Mega 7 program and compared with sequences stored in the GenBank®. Analyzes showed that the population of R. microplus studied did not present the expected mutation but a different mutation at site 2134. In the DNA of resistant and moderately resistant ticks, it was observed the substitution of a thymine for a cytosine, T2134C, that to the translation generates the change from a phenylalanine to a leucine, unlike the mutation previously reported that generates the change of a phenylalanine for a isoleucine. This shows the presence of a novel polymorphism that has not been reported in other studies with this tick species and that would generate a new molecular marker of pyrethroid resistance for populations of this mite.Key Words: ticks; chemical resistance; pesticides; mutations; polymerase chain reaction

Lake Rio Cuarto is a meromictic maar lake located in the low plains of northern Costa Rica. Its plankton composition has been studied several times since the decade of 1970. Yet most studies made short term surveys, and at least one study lasted for one year. Here we present data on phytoplankton and zooplankton composition from a four year study of the lake, from 2013 to 2017. Phytoplankton was studied from subsurface samples, preserved in Lugol’s solution and zooplankton from 20 m vertical hawls of a 64 um mesh net, and preserved with formaline and later transferred to 95% etanol. Phytoplankton composition included 54 taxa, most of them from the were Chlorophyta, followed by Cyanobacteria and Bacillariophyta. The most abundant were Synechococcus spp., Aphanocapsa sp. Coenochloris fotii, Chlorella sp. and Discostella stelligera. Total phytoplankton decreased from 2013 to 2017, mainly due to a decrease in Cyanobacteria. Zooplankton comprised 14 taxa, 5 cladocerans, 4 copepods, 1 diptera and 4 rotifers. The most abundant were Keratella cochlearis, Brachionus falcatus, Eubosmina tubicen and Arctodiaptomus dorsalis. There was a substitution of dominant species through time, at first (2013-2014) K. cochlearis and E. tubicen alternated in dominance, and later (2015-2016), A. dorsalis, Diaphanosoma sp. and Ceridaphnia sp. became dominant, with a return of K. cochlearis by 2017. The relationship between both components of the plankton is a complex result of the responses of individual species of both microalgae and zooplankton. However, most zooplankton taxa should be regarded as omnivores, so those relationships are not direct causal effects. The changes that occurred during the time of the study seem to be related to changes in the conditions of the lake, since its thermocline deepened with time and became more transparent. Those changes were not cyclical on an annual basis, but seemed to occur more on a long-term basis, as has been recognized earlier in the literature about tropical lakes.

Population status of the The Apolinar’s Wren Cistothorus apolinari (Passeriformes: Troglodytidae) in seven wetlands of the Sabana de Bogotá, Colombia. The Apolinar’s Wren Cisthotorus apolinari is an endemic species of the Eastern Cordillera of Colombia currently classified Critically Endangered (CR) at the national level and Endangered (EN) worldwide, mainly due to the degradation of wetlands, their primary habitat, and the parasitism of the nests. There are few studies on the population status of this species over time in the wetlands of Sabana de Bogotá, the only inhabited areas in recent years. This paper presents the results of the monitoring carried out between June 2014 and January 2015 in seven wetlands of Sabana de Bogotá in which historical records have existed. Employing counting points and auditory censuses, the abundance of the Swamp Wren was recorded, the vegetation cover where the individuals were recorded and the abundances of Chamon Molotrhrus bonariensis. There were 63.6 hours of observation in 35 visits and 88 counting points, with nine records of C. apolinari between Tibanica, La Florida and Gualí, mainly associated with reed Schoenoplectus californicus. After an evaluation of possible biotic and abiotic factors present in the wetlands that determine the presence of the species in question, it was not found that one of them acted definitively in determining its existence, but trends are presented in some variables. These results seek to provide relevant information to contribute to the formulation of effective conservation measures for the protection of the species and its habitat throughout its distribution in the country.

Introduction: The effects of seasonal upwelling on the conditions of the water column and mesozooplankton communities are poorly understood in the coastal zones of the Eastern Tropical Pacific (ETP), despite the important role of upwelling events in the modulation of productivity in these zones. Objective: To evaluate the influence of seasonal upwelling over the Panama Bight on the structure of the water column and mesozooplankton communities in a tropical cove of the ETP. Methods: Hydrographic data and mesozooplankton samples were collected during four field campaigns in Ensenada de Utría (December 2011, February 2012, October 2013, and February 2013), an estuary located in the Northern Pacific coast of Colombia. Non-parametric and multivariate analyses were used to evaluate seasonal differences in the environmental and biotic variables. Results: Surface waters were warm (> 25 °C) and presented low salinities (< 30) throughout the study period. In contrast, subsurface waters were colder (< 20 °C), saltier (> 33), and presented low dissolved oxygen concentrations (< 2.0 ml l-1) during the dry season (January - March), whereas the water column was homogeneous during the rainy season (April - December). Despite the seasonal changes in the environmental conditions, the expected enhancement in the productivity of the system during the dry season (i.e., higher biomass and abundance of the mesozooplankton) only occurred in February 2012. Contrary to expectations, ichthyoplankton abundance was higher during the rainy season, when the assemblage was dominated by the larvae of anchovy (Cetengraulis mysticetus) and an unidentified Gobiidae. Conclusions: The entrance of upwelled waters into Ensenada de Utría is an important factor modulating the seasonal changes observed in the water column. However, there is high interannual variability in the response of mesozooplankton communities to the upwelling events. Because upwelled waters are oxygen-depleted and more acidic, the entrance of upwelled waters into Ensenada de Utría could be causing physiological stress to the benthic and pelagic organisms inhabiting the deepest zones of the cove. This condition may worsen in the future given the predicted increase of deoxygenation and ocean acidification due to climate change.

Ability of many species of lizards to decrease their maintenance cost during changes in environmental temperatures is probably related to their success in coping with a fluctuating environment. In Argentina, Liolaemus chacoensis is a species known in the Arid Chaco sector of Plain, this region is a subtropical area that presents well-marked seasonal differences and environmental mean temperatures are increasingly variable. The aim of this work was to determine how environmental temperatures influence the thermoregulation of L. chacoensis and to know if the population responds as a unit or there are differences between sex and season. The individuals were captured by hand in the southern sector of Valle Fértil, province of San Juan. A total of 44 adult individuals were captured during the months of November 2014 (spring), February 2015 (summer) and March 2015 (autumn). In spring, 17 individuals were captured (9 females and 8 males); for the summer there were 10 individuals in total (5 females, 5 males) and in autumn 17 lizards (7 females, 10 males). The body temperature (Tb), temperature of substrate (Ts) and air (Ta) were recorded and the thermal availability of the habitat was evaluated from the perspective of a non-thermoregulatory organism, using biophysical models. In the laboratory, selected temperature (Tsel) was studied. Then the thermoregulatory efficiency index (E) was calculated. The field body temperature in autumn was 3.86 °C lower with respect to spring and 2.84 °C lower than that of summer, which is related to the dependence found between Tb and Ta. The mean of Tsel between the seasonal was similar (P > 0.05). The thermoregulatory efficiency index indicates that L. chacoensis would behave like a moderate thermoregulator (E = 0.33), except for autumn (E = 0.01), where it is observed that they tend to have no thermoregulation. When analyzing the different population segments of L. chacoensis, a marked seasonal heterogeneity was observed in the thermal biology and the active selection of the microsites seems to be a mechanism responsible for maintaining the body temperature of the species.

La micología es la ciencia que se dedica al estudio de los hongos. Es un área extensa y diversificada, cuyos aportes van desde la generación de conocimiento hasta el desarrollo tecnológico de productos. Pero ¿qué tanto se conoce fuera de la comunidad científica del reino Fungi? En México, desde tiempos prehispánicos se tiene la tradición del consumo de hongos silvestres comestibles, entre los diversos grupos originarios que se distribuyen a lo largo del territorio mexicano. El consumo de hongos como una tradición, se encuentra ubicado en gran parte, hacia el centro del país. No obstante, también es posible encontrar esta tradición en algunas regiones del sureste mexicano. Elementos como el clima y la vegetación contribuyen a la prosperidad de los hongos en el ecosistema y figuran como un recurso muy apreciado por las comunidades indígenas, ya que inclusive estas poseen nombres vernáculos que les permiten diferenciar un hongo de otro, es decir, aún conservan un enorme repositorio de conocimiento empírico. Sin embargo, para aquella porción de la sociedad que no forma parte de estos grupos étnicos, o que no posee conocimientos especializados o empíricos en torno a las ciencias biológicas, el consumo de hongos se encuentra restringido de manera general a aquellos encontrados en el supermercado. Y ¿cuál es la labor que se ha hecho y se está realizando en divulgación micológica en México? Leer más

Mangroves have different degrees of interaction between oceanographic, climatic, geomorphological and soil conditions. Those interactions have strong impacts on local salinity conditions and availability of water and nutrients at local level, and on mangrove structure and composition. Based on the analysis of aerial photographs, field sampling and statistical multivariate analysis, floristic composition and structure of the mangroves present in the Sanguaré Natural Reserve were analyzed. Three types of forests were identified according to the physiographic classification of mangroves. A fridge mangrove dominated by Rhizophora mangle L. in a juvenile state, with low structural development, and two types of inland or basin mangroves dominated by Avicennia germinans (L.) L. The first of them, located behind the fridge mangrove, showed high salinity in the soil and in the interstitial water, predominance of sandy sediments, and low values of height and diameter at breast height (DBH) average of the trees. The second, with a low number of adult trees in all diameter categories, high basal area, low natural regeneration potential, and high concentrations of Fe and Cu in the soil, probably associated with contamination by domestic spills. The location of the first inner mangrove behind the fridge mangrove reveals the typical zonation of many mangroves in the world. The floristic composition, structure and distribution of the mangroves in the Sanguaré Reserve are the result of the interaction of local environmental variables such as salinity and soil texture, as well as the anthropic intervention prior to the establishment of the reserve and the current human presence being very close to the mangroves.

Because of the influence of different human activities, rivers and their associated biodiversity are under stress. The aim of this study was to evaluate the diversity of aquatic macroinvertebrates of the Jordan River and its relation to water quality. Mining, water harvesting, livestock, agriculture, recreation and illegal occupation of the territory; take place in the evaluated section (5650m). A sampling site was established at 1173 m (E1), here the river receives wastewater. The second, at 1069m, (E2) was set up before the intake of an aqueduct. And the third, at 1019m, (E3) after the inlet pipe. Concentrations of physicochemical variables (n = 15) were measured. Aquatic macroinvertebrates were collected in gravel, pebbles and macrophytes using Surber nets (0.36 m2, 500 µm), a screen net (1.6 m2, 350 µm) and a D-net (0.9 m2, 500 µm). The assemblage structure was assessed using abundance categories. The diversity of aquatic macroinvertebrate physicochemical variables were associated using canonical correspondence analysis (CCA). The physicochemical variables showed that E3 was the most contaminated site. There were 9 orders, 23 families and 31 taxa. E3 had the lowest richness and in E2 Rhagovelia was dominant. The CCA showed that the variables that have the greatest influence on the diversity of macroinvertebrates are oxygen, BOD5, Total Dissolved Solids (TDS) and turbidity. It is concluded that the diversity of macroinvertebrates decreases with increasing organic matter possibly due to sewage and flow decrease.