[Composition of the Araneae (Arachnida) fauna of the provincial Iberá Reserve, Corrientes, Argentina]. / Composición de la fauna de Araneae (arachnida) de la Reserva provincial Iberá, Corrientes, Argentina.

A survey of the spider community composition and diversity was carried out in grasslands and woods in three localities: Colonia Pellegrini, Paraje Galarza and Estancia Rinc6n (Iberá province Reserve). Pit fall traps, leaf litter sifting, foliage beating, hand collecting and sweep nets were used. Shannon's diversity index, evenness, Berger-Parker's dominance index, beta and gamma diversity were calculated, and a checklist of spider fauna was compiled. Species richness was estimated by Chao 1, Chao 2, first and second order Jack-knife. A total of 4,138 spiders grouped into 150 species from 33 families of Araneomorphae and two species from two families of Mygalomorphae were collected. Five species are new records for Argentina and eleven for Corrientes province. Araneidae was the most abundant family (39.8%), followed by Salticidae (10.9%), Anyphaenidae (7.9%), Tetragnathidae (7.4%), and Lycosidae (5.5%). The other families represented less than 5% of the total catch. The web-builder guild had the highest number of specimens and the highest richness index. The abundance, observed richness, Shannon diversity and evenness indexes were highest in Colonia Pellegrini woodland and Paraje Galarza grassland. Alpha diversity represented 89% of the gamma; the remaining 11% corresponded to beta diversity. According to the indexes, between 67% and 97% of the existing spider fauna was represented in the collected specimens from Iberá.

Composición de la fauna de Araneae (Arachnida) de la Reserva provincial Iberá, Corrientes, Argentina

Composition of the Araneae (Arachnida) fauna of the provincial Iberá Reserve, Corrientes, Argentina. A survey of the spider community composition and diversity was carried out in grasslands and woods in three localities: Colonia Pellegrini, Paraje Galarza and Estancia Rincón (iberá province Reserve). Pit fall traps, leaf litter sifting, foliage beating, hand collecting and sweep nets were used. Shannon’s diversity index, evenness, Berger-Parker’s dominance index, ß and diversity were calculated, and a checklist of spider fauna was compiled. Species richness was estimated by Chao 1, Chao 2, first and second order Jack-knife. A total of 4 138 spiders grouped into 150 species from 33 families of Araneomorphae and two species from two families of Mygalomorphae were collected. Five species are new records for Argentina and eleven for Corrientes province. Araneidae was the most abundant family (39.8%), followed by Salticidae (10.9%), Anyphaenidae (7.9%), Tetragnathidae (7.4%), and Lycosidae (5.5%). The other families represented less than 5% of the total catch. The web-builder guild had the highest number of specimens and the highest richness index. The abundance, observed richness, Shannon diversity and evenness indexes were highest in Colonia Pellegrini woodland and Paraje Galarza grassland. Alpha diversity represented 89% of the gamma; the remaining 11% corresponded to ß diversity. According to the indexes, between 67% and 97% of the existing spider fauna was represented in the collected specimens from iberá. Rev. Biol. Trop. 57 (1-2): 339-351. Epub 2009 June 30.

Se estudió la composición y diversidad de la comunidad de arañas de la Reserva provincial iberá, Corrientes, Argentina. Se realizaron capturas en bosque y pastizal en Colonia Pellegrini, Paraje Galarza y Estancia Rincón por medio de las técnicas de muestreo: trampas "pit-fall", tamizado, golpeteo de follaje, observación directa y red de arrastre. Las arañas se agruparon en gremios y se compiló un inventario. La similitud entre localidades y unidades ambientales se midió con el índice de Jaccard, y se calcularon los índices de diversidad de Shannon, equitabilidad, dominancia de Berger-Parker, y la diversidad beta y gamma. Para estimar la riqueza de especies se utilizó Chao 1, Chao 2, Jackknife 1 y 2. En total se recolectaron 4 138 arañas, se identificaron 33 familias y 150 especies de Araneomorphae, y dos familias y dos especies de Mygalomorphae. Cinco especies son nuevos registros para Argentina y 11 para la provincia de Corrientes. Araneidae fue la familia más abundante (39.8%), seguida por Salticidae (10.9%), Anyphaenidae (7.9%), Tetragnathidae (7.4%), Lycosidae (5.5%), y las restantes familias representaron menos del 5% de la captura total. El gremio de arañas tejedoras de telas orbiculares fue el de mayor abundancia y riqueza de especies. Entre las unidades ambientales, la mayor abundancia, riqueza y diversidad se verificó en el bosque de Colonia Pellegrini y en el pastizal de Paraje Galarza. La diversidad a fue alta, representó el 89% de la diversidad gamma, y la diversidad ß constituyó el 11% restante. Según los diferentes índices se capturó entre el 67% y el 97% de las especies que están presentes en la Reserva.

Arañas (Arachnida: Araneae) asociadas a dos bosques degradados del Chaco húmedo en Corrientes, Argentina

Spiders (Arachnida: Araneae) associated with two degraded forests in the humid Chaco of Corrientes, Argentina. The advancing degradation of the forest in the biogeographic Chaco province (Argentina) produces an important loss of its little known biodiversity. We studied the spider biodiversity in two forests of Corrientes, Argentina’s "Distrito Oriental Húmedo del Chaco": Laguna Brava and El Perichón. Seasonal samplings of foliage and fallen leaves between 2001 and 2002 produced 2 067 individuals from 33 families and 226 species/ morphospecies). The families Araneidae, Anyphaenidae, Salticidae and Theridiidae were the most abundant in both forests. The "orb weavers" guild had the highest number of specimens (n=382) and "stalkers" the highest richness (S=56). in Brava, highest abundance was in the summer (n=287) and spring (n=273), in Perichón, it was in winter (n=315). The specific richness and the diversity indexes were higher in Brava (S=134, H´=4.23, E=0.86, D=0.023) than in Perichón (S=127, H´=4.08, E=0.84, D=0.029). The similarity value between both forests was MH=0.611. Rev. Biol. Trop. 55 (3-4): 899-909. Epub 2007 December, 28.

El importante avance de la degradación de bosques en la Provincia Biogeográfica del Chaco, Argentina, conlleva una pérdida importante de su poco conocida biodiversidad. Se realizó un estudio de la fauna de arañas en dos bosques de la provincia de Corrientes, Argentina, correspondientes al Distrito Oriental Húmedo del Chaco, en las localidades de Laguna Brava y El Perichón. Se realizaron muestreos estacionales entre los años 2001 y 2002. Las arañas recolectadas (2 067 individuos de 33 familias y 226 especies/morfoespecies) fueron obtenidas por golpeteo del estrato arbustivo y tamizado de hojarasca. Las familias Araneidae, Anyphaenidae, Salticidae y Theridiidae fueron las más abundantes en los dos bosques. El gremio de arañas "constructoras de telas orbiculares" presentó el mayor número de individuos (n=382) y el de "cazadoras al acecho" la mayor riqueza (S=56). En Laguna Brava se observó mayor abundancia en el verano (n=287) y primavera (n=273) y en el Perichón en invierno (n=315). La riqueza específica y el valor de los índices de diversidad, fueron mayores en Laguna Brava (S=134, H´=4.23, E=0.86, D=0.023) que en El Perichón (S=127, H´=4.08, E=0.84, D=0.029). La similitud entre ambos bosques fue MH=0.611.

[Spiders (Arachnida: Araneae) associated with two degraded forests in the humid Chaco of Corrientes, Argentina]. / Arañas (Arachnida: Araneae) asociadas a dos bosques degradados del Chaco húmedo en Corrientes, Argentina.

The advancing degradation of the forest in the biogeographic Chaco province (Argentina) produces an important loss of its little known biodiversity. We studied the spider biodiversity in two forests of Corrientes, Argentina's "Distrito Oriental Húmedo del Chaco": Laguna Brava and El Perich6n. Seasonal samplings of foliage and fallen leaves between 2001 and 2002 produced 2067 individuals from 33 families and 226 species/morphospecies). The families Araneidae, Anyphaenidae, Salticidae and Theridiidae were the most abundant in both forests. The "orb weavers" guild had the highest number of specimens (n=382) and "stalkers" the highest richness (S=56). In Brava, highest abundance was in the summer (n=287) and spring (n=273), in Perichón, it was in winter (n=315). The specific richness and the diversity indexes were higher in Brava (S=134, H'=4.23, E=0.86, D=0.023) than in Perichón (S=127, H'=4.08, E=0.84, D=0.029). The similarity value between both forests was MH=0.611.

Arthropods associated with the crown of Mauritia flexuosa (Arecaceae) palm trees in three different environments from Brazilian Cerrado

Canopy arthropods, mainly from palm trees, are little known in the Brazilian Cerrado. In order to describe the arthropod community structure associated with the crown of Mauritia flexuosa (Arecaceae), we sampled 150 palm trees in six "veredas" of the Federal District, Brazil, in wild, rural and periurban areas in the rainy season. The arthropods within abandoned bird nests, mammal refuges, leaves and organic matter were manually collected, preserved in ethanol 70 percent and separated by order, family, morphospecies and feeding guilds. Stem height and diameter of the palm crowns were measured and leaves and bird nests were counted. We collected 3,862 arthropods, from 15 orders, 45 families and 135 morphospecies. The most abundant orders were Coleoptera (28.6 percent), Blattodea (21.8 percent), Collembola (11.4 percent) and Hemiptera (10.2 percent). The families Blaberidae, Entomobryidae, Reduviidae, Oniscidae, Staphylinidae, Carabidae and Formicidae, represented 82.1 percent of all individuals collected. The majority of morphospecies was not abundant, 71 (52.6 percent) were represented by less than 1 individual/tree. Coleopterans accounted for the highest number of morphospecies (43.7 percent) followed by Araneae (20.0 percent). The analysis of the arthropod feeding guilds showed prevalence of predatory/hematophagous ones (36.0 percent). Arthropod richness and abundance presented smaller values for periurban environment. The number of bird nests presented positive correlation with abundance and richness; this was not found when considering the measurements of the palm trees. The importance of M. flexuosa for the maintenance of the arthropod fauna of the "veredas" in Cerrado biome is discussed.

Artrópodos associados à copa de árvores, principalmente palmeiras, são pouco conhecidos no Cerrado. Para descrever a estrutura da comunidade de artrópodos associada à copa de Mauritia flexuosa (Arecaceae) foram amostradas 150 palmeiras em seis "veredas" do Distrito Federal, de áreas silvestres, rurais e periurbanas na estação chuvosa. Os artrópodos presentes nos ninhos abandonados de aves, refúgios de mamíferos, folhas e matéria orgânica foram coletados manualmente, fixados em etanol 70 por cento e separados em ordem, família, morfoespécie e guildas alimentares. As características das palmeiras medidas foram altura da estipe, diâmetro da copa, número de folhas e de ninhos de aves nas palmeiras. Foram coletados 3.862 indivíduos, pertencentes a 15 ordens, 45 famílias e 135 morfoespécies. As ordens mais abundantes foram Coleoptera (28,6 por cento), Blattodea (21,8 por cento), Collembola (11,4 por cento) e Hemiptera (10,2 por cento). As famílias Blaberidae, Tenebrionidae, Entomobryidae, Reduviidae, Oniscidae, Staphylinidae, Carabidae e Formicidae representaram 82,1 por cento de todos os indivíduos coletados. A maioria das morfoespécies foi pouco abundante, 71 (52,6 por cento) apresentaram uma abundância média igual ou menor que 1 indivíduo/palmeira. Coleoptera compreendeu o maior número de morfoespécies (43,7 por cento) seguida de Araneae (20,0 por cento). A análise das guildas alimentares mostrou prevalência de predadores e hematófagos (36,0 por cento). A riqueza e a abundância de artrópodos foram menores no ambiente periurbano. O número de ninhos de aves apresentou correlação positiva com abundância e riqueza, o que não ocorreu com as medidas das palmeiras. A importância de M. flexuosa para a manutenção da artropodofauna nas "veredas" no bioma Cerrado é discutida.

Arthropods associated with the crown of Mauritia flexuosa (Arecaceae) palm trees in three different environments from Brazilian Cerrado.

Canopy arthropods, mainly from palm trees, are little known in the Brazilian Cerrado. In order to describe the arthropod community structure associated with the crown of Mauritia flexuosa (Arecaceae), we sampled 150 palm trees in six "veredas" of the Federal District, Brazil, in wild, rural and periurban areas in the rainy season. The arthropods within abandoned bird nests, mammal refuges, leaves and organic matter were manually collected, preserved in ethanol 70% and separated by order, family, morphospecies and feeding guilds. Stem height and diameter of the palm crowns were measured and leaves and bird nests were counted. We collected 3,862 arthropods, from 15 orders, 45 families and 135 morphospecies. The most abundant orders were Coleoptera (28.6%), Blattodea (21.8%), Collembola (11.4%) and Hemiptera (10.2%). The families Blaberidae, Entomobryidae, Reduviidae, Oniscidae, Staphylinidae, Carabidae and Formicidae, represented 82.1% of all individuals collected. The majority of morphospecies was not abundant, 71 (52.6%) were represented by less than 1 individual/tree. Coleopterans accounted for the highest number of morphospecies (43.7%) followed by Araneae (20.0%). The analysis of the arthropod feeding guilds showed prevalence of predatory/hematophagous ones (36.0%). Arthropod richness and abundance presented smaller values for periurban environment. The number of bird nests presented positive correlation with abundance and richness; this was not found when considering the measurements of the palm trees. The importance of M. flexuosa for the maintenance of the arthropod fauna of the "veredas" in Cerrado biome is discussed.

Life cycle and reproductive patterns of Triatoma rubrovaria (Blanchard, 1843) (Hemiptera: Reduviidae) under constant and fluctuating conditions of temperature and humidity

O presente trabalho teve como objetivo avaliar a influência da temperatura e umidade relativa sobre o ciclo biológico, mortalidade e fecundidade de Triatoma rubrovaria. Formaram-se quatro coortes, cada uma de 60 ovos recentemente colocados. As coortes foram divididas em dois grupos: O grupo condições controlada foi mantido em estufa com temperatura e umidade constantes, e o grupo temperatura ambiental foi mantido em condições variáveis de temperatura e umidade. O tempo de incubação dos ovos foi de 15.6 condições controlada e de 19.1 dias temperatura ambiental. O período de desenvolvimento de ovo a adulto foi de dez meses em condições controlada e 4 meses mais extenso em temperatura ambiental. A taxa de eclosão foi 99.1% em condições controlada e 98.3% em temperatura ambiental. A fecundidade foi 817.6 condições controlada e 837.1 temperatura ambiental. O percentual de mortalidade ninfal foi 52.6% no grupo condições controlada e 51.8% no grupo temperatura ambiental. As variações de temperatura e umidade relativa exercem influência no ciclo biológico e em alguns padrões reprodutivos desta espécie, mas não em sua mortalidade.

Life cycle and reproductive patterns of Triatoma rubrovaria (Blanchard, 1843) (Hemiptera: Reduviidae) under constant and fluctuating conditions of temperature and humidity.

The aim of this study was to evaluate the temperature and relative humidity influence in the life cycle, mortality and fecundity patterns of Triatoma rubrovaria. Four cohorts with 60 recently laid eggs each were conformed. The cohorts were divided into two groups. In the controlled conditions group insects were maintained in a dark climatic chamber under constant temperature and humidity, whereas triatomines of the ambiental temperature group were maintained at room temperature. Average incubation time was 15.6 days in the controlled conditions group and 19.1 days in the ambiental temperature. In group controlled conditions the time from egg to adult development lasted 10 months while group ambiental temperature took four months longer. Egg eclosion rate was 99.1% and 98.3% in controlled conditions and ambiental temperature, respectively. Total nymphal mortality in controlled conditions was 52.6% whereas in ambiental temperature was 51.8%. Mean number of eggs/female was 817.6 controlled conditions and 837.1 ambiental temperature. Fluctuating temperature and humidity promoted changes in the life cycle duration and in the reproductive performance of this species, although not in the species mortality.

[Epidemiology of Chagas disease in San Roque, Corrientes. Triatomine infestation and human seroprevalence]. / Epidemiología de la enfermedad de Chagas en San Roque, Corrientes. Infestación por triatominos y seroprevalencia humana.

This investigation was aimed to evaluate triatomine colonization in domestic and extradomestic ecotopes located around a palm community, to determine triatomines infection index and to obtain human seroprevalence rates. Samplings were performed in spring 1998 and summer 1999 in Colonia Laurel, Department San Roque, Corrientes, Argentina. Timed-collection of triatomines (man/hour method) was performed. Trypanosoma cruzi identity was determined by morphological criteria and by PCR. Indirect hemagglutination and indirect immunofluorescence antibody tests were used for detection of T. cruzi infection in human volunteers. Sixteen human dwellings were analized, 11 resulted infested by Triatoma infestans and two by Triatoma sordida. A total of 122 T. infestans of all age classes were collected and T. cruzi infection was recorded in 16.7%. Triatoma infestans was confirmed as the predominant species in the domicile and T. sordida in the peridomicile. Diagnosis of Chagas disease infection was performed in 77.9% (88/113) of the inhabitants and the prevalence was 26.1%. A relatively high infection rate was observed in the 0-10 age group. Seropositives percentages increased with age and reached 66.6% in older than 40 years. Presence of T. infestans, human seroreactivity to T. cruzi, < or = 4 year old seropositives and precarious life conditions prove that this endemic disease is still a problem in the studied area.

[Population statistics of Triatoma rubrovaria in laboratory]. / Estadísticos poblacionales de Triatoma rubrovaria en condiciones de laboratorio.

OBJECTIVE: To obtain T. rubrovaria population parameters in order to describe its demographic characteristics. METHODS: The study was carried out in the laboratory of Arthropods, Corrientes, Argentina, from October 2000 to February 2003. Eggs were grouped to form five 100-egg cohorts. Insects were fed on chickens (Gallus domesticus). The cohorts were monitored weekly and kept under controlled temperature (28 +/- 3 degrees C) and relative humidity (63 +/- 10%). A life table was constructed and other vital statistics were calculated and recorded. RESULTS: Higher mortality was recorded in the first through the fourth nymphal stadium. A constant decrease was seen from the fifth nymphal instar. Life expectancy dropped linearly after overcoming the critical stages. Adults mean survival was 50.2 weeks. The first oviposition was after 40.6 weeks. The fecundity was 859.6 eggs with an average 22.8 eggs per female. The reproductive period was 37.7 weeks. The generation time was 55.3 weeks and the net reproduction rate was 133.7. The intrinsic rate of weekly increment was 0.088. In a stable age distribution the population would be composed of 25.3% eggs, 72.3% nymphs and 2.4% adults. Adults accounted for more than 70% of the total reproductive value. CONCLUSIONS: Triatoma rubrovaria had a long survival as imago, a late first reproduction and a low intrinsic rate of natural increase.

Estadísticos poblacionales de Triatoma rubrovaria en condiciones de laboratorio / Population statistics of Triatoma rubrovaria in laboratory

OBJETIVO: Obtener parámetros poblacionales de T. rubrovaria a fin de caracterizar demográficamente a esta especie. MÉTODOS: La investigación se realizó entre octubre de 2000 y febrero de 2003 en el laboratorio de artrópodos, Corrientes, Argentina. Se conformaron cinco cohortes de 100 huevos cada una. Los insectos se alimentaron sobre gallina (Gallus domesticus). Las cohortes se controlaron semanalmente. La experiencia se llevó a cabo en condiciones controladas de temperatura (28±3ºC) y humedad relativa del aire (63±10 por ciento). Se elaboraron tablas completas de vida y se obtuvieron estadísticos vitales. RESULTADOS: La mayor mortalidad se registró en ninfas de primero a cuarto estadio. A partir del quinto estadio el número de individuos decreció en forma constante. La expectativa de vida, después de superar las edades críticas, disminuyó en forma lineal. La supervivencia media de los adultos fue 50,2 semanas. La primera oviposición ocurrió a las 40,6 semanas. La fecundidad fue 859,6 huevos, con una media de 22,8 huevos. El período reproductivo fue de 37,7 semanas. El tiempo generacional fue de 55,3 semanas y la tasa neta de reproducción 133,7. La tasa intrínseca de incremento natural resultó 0,088. En una distribución estable de edades 25,3 por ciento correspondería al estado de huevo, 72,3 por ciento al estado ninfal y 2,4 por ciento al estado adulto. Los adultos contribuyeron con más del 70 por ciento al valor reproductivo total. CONCLUSIONES: Triatoma rubrovaria se caracterizó por una supervivencia prolongada como imago, una edad de la primera reproducción tardía y una tasa intrínseca de incremento natural baja.

Epidemiología de la enfermedad de Chagas, Departamento General Paz, Argentina / Chagas' disease epidemiology in the province of General Paz, Argentina

OBJETIVO: El objetivo del presente trabajo fue investigar la colonización por triatominos en ambientes domésticos y peridomésticos y evaluar la seroprevalencia de infectados chagásicos en localidades rurales. MÉTODOS: La investigación se realizó en General Paz, Corrientes, Argentina. Las viviendas y peridomicilios se seleccionaron mediante un muestreo simple al azar. La búsqueda de triatominos se efectuó por el método captura/hora/hombre. Los insectos se identificaron taxonómicamente y se clasificaron según sexo y edad. La infección por Trypanosoma cruzi se detectó por observación directa de las heces al microscopio y por la técnica de la reacción en cadena de la polimerasa (PCR). Se evaluaron serológicamente a pobladores voluntarios mediante las técnicas de hemaglutinación indirecta (HAI) y ensayo inmunoenzimático (ELISA). Se hallaron los índices de infestación, densidad, colonización, infección natural y dispersión. RESULTADOS: Se analizaron 42 viviendas y 50 peridomicilios. En el domicilio los índices de infestación e infección de Triatoma infestans fueron 23,8 y 19,4 respectivamente. Los índices de densidad, colonización y dispersión fueron 2,1; 47,0 y 50,0 respectivamente. La infestación del peridomicilio por T. infestans fue 5,9 por ciento y por T. sordida 11,8 por ciento. T. sordida resultó infectada por Trypanosoma cruzi en un 2,0 por ciento. La seroprevalencia al T. cruzi de los 85 pacientes fue del 22,3 por ciento. CONCLUSIONES: Se estima que en el área investigada la transmisión del T. cruzi está interrumpida. Sin embargo, la presencia de infectados humanos y de T. infestans parasitadas posibilitan el reinicio del ciclo de transmisión. Se proponen acciones de rociado con insecticidas con el objeto de eliminar las poblaciones del vector

[Chagas' disease epidemiology in the province of General Paz, Argentina]. / Epidemiología de la enfermedad de Chagas, Departamento General Paz, Argentina.

OBJECTIVE: The aim of this study was to evaluate triatomine colonization in domestic and peridomestic ecotopes and to assess the seroprevalence of Chagas' disease in rural areas. METHODS: The study was carried out in the province of General Paz, Corrientes, Argentina. Human dwellings and peridomestic ecotopes were randomly selected. Triatomines were collected using the man/hour/capture method. The insects were taxonomically determined and classified by age and sex. Trypanosoma cruzi infection was detected through direct microscopy of feces and polymerase chain reaction (PCR). Diagnosis of Chagas infection in volunteer residents was performed using indirect hemagglutination (IHA) and immunoenzimatic assay (ELISA). Infestation, density, colonization, natural infection and dispersion indexes were recorded. RESULTS; A total of 42 households and 50 peridomestic areas were examined. Triatoma infestans domestic infestation and infection indexes were 23.8 and 19.4; respectively. Density, colonization and dispersion indexes were 2.1; 47.0 and 50.0; respectively. Of all, 5.9% of peridomiciles were infested by T. infestans and 11.8% by Triatoma sordida. Trypanosoma cruzi infection was observed in 2.0% of T. sordida. The seroprevalence rate obtained from 85 human sera analyzed was 22.3%. CONCLUSIONS: The results suggest a halt in T. cruzi transmission in the study area. Nevertheless the presence of seroreactive individuals and infected T. infestans vectors might facilitate the resurgence of the transmission cycle. Control actions with the use of insecticides might be considered in order to eliminate vector populations.

Estadísticos poblacionales de Triatoma sordida Stäl 1859 (Hemiptera: Reduviidae) en condiciones experimentales / Population statistics of Triatoma sordida Stäl 1859 (Hemiptera: Reduviidae), in experimental conditions

Foram estudados diferentes parâmetros populacionais de Triatoma sordida em condiçöes de laboratório. Realizou-se um seguimento longitudinal de quatro coortes de 100 ovos cada uma; os insetos foram criados a 28§C ñ 3§C e 63 por cento ñ 10 por cento de umidade relativa, e alimentados cada sete dias sobre galinha (Gallus domesticus) durante 40'. As coortes foram controladas uma vez por semana. A expectativa de vida média dos machos foi de 37,4 semanas e a das fêmeas de 36,8. O tempo médio de desenvolvimento foi de 61,7 semanas. A taxa reprodutiva líquida indica que esta populaçäo aumentará 143,2 vezes durante cada geraçäo. A taxa intrínseca do crescimento natural foi de 0,082 por semana. A média do valor máximo reprodutivo verificou-se na terceira semana no início do estádio adulto. A distribuiçäo estável de idades de T. sordida seria de 32 por cento ovos, 26 por cento ninfas do primeiro estádio, 19 por cento ninfas do segundo estádio, 13 por cento ninfas do terceiro estádio, 6 por cento ninfas do quarto estádio, 3 por cento ninfas do quinto estádio e 1 por cento de adultos. A análise dos parâmetros permite considerar que esta espécie comporta-se como K-estrategista em condiçöes experimentais

Presencia de triatoma sordida Stäl, 1859 en ecotopos urbanos de la cuidad de Corrientes, Argentina / Presence of triatoma sordida Stäl, 1859 in Corrientes city urban ecotopes

Com o objetivo de verificar a presença de T. sordida em ecótopos urbanos da cidade de Corrientes, Argentina, tomaram-se como base um habit extradomiciliário e a domicílio. Em um pombal situado no parque Mitre foi realizado censo da polulaçäo de T. sordida para o qual foram dissecados 400 ninhos de pombas (Columbia livia). Os exemplares detectados no domicílio foram enviados por moradores ao Laboratório de Artrópodos. Os triatomíneos foram determinados sistematicamente e por classe de idade. A matéria fecal dos mesmos foi examinada ao microscópio com 400 aumentos para a identificaçäo do Trypanosoma cruzi. No pombal coletaram-se 1.920 exemplares de T. sordida, populaçäo constituída por ovos, ninfas e adultos. Em 27 domicílios foi constatada a presença desta espécie, capturando-se 13 ovos, 33 ninfas de diferentes estádios, 27 fêmeas e 9 machos. Nenhum triatomíneo resultou infectado por T. cruzi. Os adultos de T. sordida deslocaram-se ao domicílio na primavera e veräo, sendo que 33 por cento do material encontrado nos domicílios correspondeu a fêmeas. Comprovaram-se a adaptaçäo de T. sordida a um habitat extradomiciliário e a sua tendência a invadir domicílio, fatos que se deveriam ter em conta nos programas de controle de vectores