Predation on Eggs of Aedes aegypti (Diptera: Culicidae): Temporal Dynamics and Identification of Potential Predators During the Winter Season in a Temperate Region

In temperate regions, the populations of Aedes aegypti (L.) remain in the egg stage during the cold season. The ability of these eggs to survive until the next favorable season is affected by several mortality factors, including the action of predators. In the present study, we analyzed the temporal dynamics of the loss of eggs and identified predators of Ae. aegypti eggs along the unfavorable season in a temperate region of Argentina. To this end, eggs were exposed in field conditions in pitfall traps, where walking arthropod taxa were captured during 1-wk periods from early June to early September (Austral winter).The association of arthropod taxa with the loss of eggs was analyzed to identify potential predators. Based on the results obtained, two taxa were chosen to confirm their capacity to consume eggs in a laboratory study. The proportion of lost eggs and the abundance of predators were significantly higher in the winter–spring transition, although results were heterogeneous among traps in all exposure periods. Ants of the genus Strumigenys, isopods of the species Armadillidium vulgare (Isopoda: Armadilloidea), and dermapterans of the species Euborellia annulipes (Dermaptera: Anisolabidae) were positively associated with a high proportion of lost eggs. In laboratory conditions, A. vulgare and E. annulipes consumed the offered eggs, thus confirming their predator capacity.This study represents the first record of predation of Ae. aegypti eggs in temperate South America and the first evidence of dermapterans consuming mosquito eggs.Fil: Byttebier, Bárbara. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Fischer, Sylvia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin

Seasonal and environmental variables related to the abundance of immature mosquitoes in rain pools of a peri-urban park of Buenos Aires (Argentina)

The aim of the present study was to investigate the variables associated with the composition of mosquito species in rain pools of ‘Bosque de Ezeiza’, a large peri-urban forested park of Buenos Aires city, Argentina. A total of 12 rain pools were sampled biweekly over a 1-yr period in search of mosquito immature stages. Mosquito immature stages were present in all the occasions in which water bodies were recorded. A total of 14 species of five genera were identified, with the highest abundances observed in autumn and spring. The total abundance varied among dates according to previous temperature, precipitation, and flooding conditions. Only one species, Psorophora cyanescens (Coquillett) (Diptera: Culicidae), was associated with extreme conditions (high temperature and prolonged period of drought). Besides drought periods, two main variables were related to species composition: temperature, which accounted for seasonal changes in species composition, and flooding history, which accounted for the predominance of floodwater mosquito species on recently flooded dates and for that of stagnant water species on dates with a longer permanence of water. Regarding the pools, the most important variables accounting for species composition were the insolation level and the variability in the flooded area, with floodwater mosquitoes associated with pools with high variability in the flooded area. Interestingly, Culex (Mel.) pilosus (Dyar and Knab) (Diptera: Culicidae) showed temporal and spatial dynamics more similar to floodwater species than to stagnant water species in the rain pools studied.Fil: Urcola, Juan Ignacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Fischer, Sylvia Cristina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin

Hatching Response of Aedes aegypti (Diptera: Culicidae) Eggs at Low Temperatures: Effects of Hatching Media and Storage Conditions

In temperate regions, Aedes aegypti (L.) (Diptera: Culicidae) populations remain in the egg stage during the cold season. To ensure the start of a new breeding season, eggs should hatch at the beginning of a favorable period. The aim of the current study was to investigate the hatching response of two Ae. aegypti egg batches collected and stored for 3 mo under different conditions, to different low immersion temperatures. Two different hatching media (water and yeast solution) were used for the first batch and only one (water) for the second egg batch. Eggs were immersed for 8 d, during which the number of hatched eggs was recorded daily. The proportion of hatched eggs, delay of the hatching response, proportion of dead larvae, and proportion of remaining eggs within the first egg batch were compared between the two hatching media at each temperature. These parameters also were compared between the two batches immersed in water. Hatching rates were higher and faster in the yeast solution. The hatching response was lower at lower immersion temperatures and among eggs stored under field conditions at colder temperatures (second batch). Among the eggs stored in the laboratory (first batch), older eggs exhibited lower hatching response. The proportion of dead larvae was higher in the yeast solution and in the eggs stored in the laboratory. The conditions that triggered a lower hatching response led to higher proportions of remaining eggs, allowing the population to maintain an egg bank for future favorable opportunities.Fil: Byttebier, Bárbara. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: de Majo, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Fischer, Sylvia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin

Effects of Thermal Heterogeneity and Egg Mortality on Differences in the Population Dynamics of Aedes aegypti (Diptera: Culicidae) Over Short Distances in Temperate Argentina

In temperate regions, the seasonal dynamics of Aedes aegypti (L.) (Diptera: Culicidae) is mainly influenced by temperature, whereas the probability of local extinction depends on the egg mortality during the cold season. The aim of the current study was to assess the importance of temperature and egg mortality in determining the differences in the oviposition dynamics of Ae. aegypti between favorable and less favorable areas in Buenos Aires City (Argentina). Year-round temperature dynamics were monitored, and oviposition dynamics were experimentally studied with ovitraps at two sites. Daily egg mortality values were calculated from a previous study performed at the same sites. The relative contribution of the differences in temperature and egg mortality between sites to the oviposition dynamics was assessed by means of a mathematical stochastic population dynamics model for Ae. aegypti. The results showed higher temperature and lower daily egg mortality at the site where higher oviposition activity was recorded. A larger influence of temperature than of egg mortality on population abundance during most of the activity season was detected in the results of the simulations. Our results showed a temperature gradient that relates to the distance to the Río de la Plata river and contributes to explaining the spatial heterogeneity in Ae. aegypti population abundances previously reported. The hypothesis of local extinctions because of egg mortality during the winter was not supported by the present analysis. The differences between field oviposition dynamics and simulation results suggest that rainfall might also be an important variable under extremely dry conditions.Fil: de Majo, María Sol. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Grupo de Estudio de Mosquitos; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina;Fil: Fischer, Sylvia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina; Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Grupo de Estudio de Mosquitos; Argentina;Fil: Otero, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires; Argentina; Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina;Fil: Schweigmann, Nicolas Joaquin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina; Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Grupo de Estudio de Mosquitos; Argentina

Increased size and energy reserves in diapausing eggs of temperate Aedes aegypti populations

Many insects overwinter in diapause, a pre-programmed anticipated response to unfavorable environmental conditions, often induced by a short-day photoperiod. Diapause involves morphological changes and increased energy stores required for metabolic demands during winter. In diapausing mosquito eggs, the accumulation of lipids plays an important role, because these molecules are the primary fuel consumed during embryogenesis and pharate larvae metabolism, and have a key role in egg desiccation resistance. The supposed inability of the mosquito Aedes aegypti to lay diapausing eggs has been recently challenged by a study on a temperate population, which showed that the inhibition of egg hatching in response to short days is possible in this species. Thus, the aim of the present study was to assess the effects of parental photoperiod on embryonic diapause-related traits, such as the triglyceride content and size of eggs laid, of two populations whose localities of origin differ in their winter length. Two colonies were maintained for each population: one under a Short-Day Photoperiod (SD: 10 h:14 h – Light:Dark) and the other under a Long-Day Photoperiod (LD: 14 h:10 h – Light:Dark). The eggs obtained from each combination of population and light treatment were used for size measurement (length, width and volume) and for the quantification of triglyceride content. Egg size showed differences between photoperiod treatments, with larger width and volume in eggs from the SD treatment. Remarkably, eggs from the SD treatment accumulated twice as many triglycerides as those from the LD treatment. Also, the eggs derived from the population having the longer winter accumulated larger amounts of triglycerides. The higher lipid content is probably contributing to a better survival during the cold season in both populations. The photoperiod-induced response in egg size and amount of triglycerides observed in this study support the hypothesis that the Ae. aegypti populations studied are able to lay diapausing eggs, a fact that provides physiological bases for the further expansion of this species to colder regions.Fil: Mensch, Julian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Di Battista, Cristian Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: de Majo, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Campos, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Fischer, Sylvia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin

Photoperiod affects female life history traits in temperate populations of Aedes aegypti from South America

In many insects, short photoperiods induce females to lay diapausing eggs, which are associated with a reduction in female fecundity, and/or with an increase in their growth rate, allowing for a larger size at adulthood. The effects of short photoperiods may also differ among populations, depending on the different selection pressures imposed by the winter conditions. Thus, this study aimed to experimentally assess the effects of short photoperiods on Aedes aegypti, an invasive mosquito species that also vectors several viral diseases. We compared life history parameters of the females reared from the first larval instar under contrasting photoperiods, in two populations from the temperate region of Argentina, one with a milder winter (BA) and the other with a harsher winter (SB). The results showed a significant increase in the time to oviposition, a trend to a larger size of females (significant only for SB) and higher inhibition of egg hatching (more pronounced in SB), in response to short photoperiods. No differences in fecundity were detected among treatments. The different reaction norms of the populations in female body size and egg hatching response suggest an adaptation to local conditions, which might favour a further expansion of A. aegypti towards colder climates.Fil: Campos, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Di Battista, Cristian Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: de Majo, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Montini, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Fischer, Sylvia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin

Introduction to socio-ecological analysis based on the collective mapping of someone’s own territory: uses made by different social actors and their associated conflicts

El presente trabajo expone una práctica de la materia “Ecología y Desarrollo” en el ámbito de una Facultad de ciencias naturales. El objetivo es fomentar la apropiación por parte del estudiantado del espacio del campus y de conceptos de conflictos socio-ambientales y sistemas socio-ecológicos. A través de un trabajo de debate y con el uso de imágenes aéreas, información bibliográfica, notas periodísticas, fotografías del lugar y el relato de un integrante del Vivero Comunitario Ciudad Universitaria, se reconstruyen históricamente los cambios en el paisaje y sus usos. Las dinámicas planteadas propiciaron la identificación de distintos actores involucrados, visualización espacial de los usos que estos hacen del espacio, y la identificación de diferentes conflictos. Esta herramienta didáctica y técnica resultó un dispositivo valioso para facilitar el diálogo entre distintos actores.The present article exposes a practice in the course “Ecology and Development” in a school of natural sciences. The objective is to promote the students’ appropriation of the campus space, the socio-environmental conflicts, and the concepts of socio-ecological systems. Through discussion and the use of aerial images, bibliographical information, journalistic notes, photographs and the narration of a member of the University Campus Community Plant Nursery, landscape changes and its uses are historically reconstructed. The work has led to the identification of different actors involved, a spatial visualization of the uses they make of space, and the identification of conflicts. This didactic and technical tool has proven to be a valuable device to facilitate dialogue among different actors.Fil: Urdampilleta, Constanza María. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Arquitectura, Diseño y Urbanismo; ArgentinaFil: Boron, Carlos Ignacio. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentina. Universidad Nacional de San Martin. Instituto de Nanosistemas; ArgentinaFil: Fischer, Sylvia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Ithuralde, Raúl Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Estudios para el Desarrollo Social. - Universidad Nacional de Santiago del Estero. Facultad de Humanidades Ciencias Sociales y de la Salud. Instituto de Estudios para el Desarrollo Social; Argentin

Aquatic and semiaquatic Coleoptera from Ernesto Tornquist Provincial Park (Buenos Aires Province, Argentina)

Se presenta el primer relevamiento de coleópteros acuáticos y semiacuáticos del Parque Provincial Ernesto Tornquist. El material entomológico estudiado se obtuvo durante las campañas de recolección de insectos acuáticos, realizadas entre los años 2005 y 2007, en las cuatro estaciones del año. Los ambientes estudiados fueron los arroyos Ventana, El Loro, Sauce Grande y dos charcos temporarios. Se identificaron en total 5.200 ejemplares pertenecientes a 9 familias, 20 géneros y 34 especies. Se brinda el listado de las especies y su distribución en la Argentina. Se citan, por primera vez para el parque, 23 especies y por primera vez para la Provincia de Buenos Aires: Austrelmis sp. e Hydrochus stolpi Germain.We present the results of the first survey on the aquatic and semiaquatic water beetles from the Ernesto Tornquist Provincial Park. The material was obtained from several quantitative samplings of aquatic insects covering all seasons from 2005 to 2007. The surveyed habitats were the Ventana, El Loro and Sauce Grande streams and two rain pools. A total of 5,200 specimens belonging to 9 families, 20 genera and 34 species of Coleoptera were identified. A list of the species known to occur in the park along with their distributional data in Argentina is presented. Twenty-three species are cited from the park for the first time. Austrelmis sp. and Hydrochus stolpi Germain are recorded for the first time from Buenos Aires Province.Fil: Fernandez, Liliana Alicia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Torres, Patricia Laura Maria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Michat, Mariano Cruz. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fischer, Sylvia Cristina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Oliva, Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Bachmann, Axel Oscar. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Meningococcemia: do diagnóstico ao tratamento – um estudo de caso

Trata-se de estudo de caso de lactente de 15 meses de idade, do sexo feminino, com diagnóstico de meningococcemia, inicialmente por meio de suspeita clínica e posteriormente confirmado com exame complementar. A paciente em questão possuía alguns fatores de risco relacionados ao desenvolvimento da doença meningocócica. No atendimento inicial foram identificados sinais de gravidade que levaram a equipe a implementar o tratamento de maneira oportuna. Nesse contexto, serão abordados conceitos pertinentes acerca do modo de transmissão, epidemiologia, manifestações clínicas, diagnóstico e tratamento da doença meningocócica. Considerando que a meningococcemia está associada à alta morbimortalidade, esse estudo de caso visa mostrar a importância de realizar a rápida suspeita e tratamento adequado para melhora do prognóstico, como na paciente apresentada neste estudo, que obteve um desfecho clínico favorável