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Identifying morphologically similar triatomine species is key to Chagas' disease vector control and surveillance, but remains challenging when only qualitative phenotypic data are available. We investigated whether morphometric and ecological variation can provide additional criteria for species delimitation by combining geometric morphometrics and ecological niche modelling to characterize two near-sibling triatomine species, Triatoma sordida and Triatoma garciabesi (Reduviidae: Triatominae). We analysed size and shape variation in 231 wings and 123 heads from one T. garciabesi and three T. sordida populations. Predicted distribution maps (21 climatic variables, 324 vector occurrence points) were produced using the Maxent method. Multivariate analyses summarized morphological and ecological variation. Wings and heads of T. sordida were significantly larger and more elongated than those of T. garciabesi. Discriminant analyses separated the species, with a partial overlap between Argentinean populations. The predicted distribution of T. garciabesi included northwest Argentina (mainly arid Chaco), whereas that of T. sordida included northeast Argentina (humid Chaco) and the Brazilian Cerrado and Caatinga ecoregions. Clear ecological niche differences were observed, with T. garciabesi occupying colder and drier areas than T. sordida. Our results show how morphometric variation and niche divergence can be used to enhance operational criteria for the delimitation of phenotypically similar triatomine species.

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

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, β and γ 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 β 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.

Spider diversity in cultures of Citrus sinensis (Rutaceae) in Corrientes province, Argentina. Spiders are predators that reduce insect pest populations in agroecosystems. In spite that the presence of spider assemblages has been described in different crop plants, no reports have been done for Citrus species in Argentina. We studied the spider community associated with cultures of Citrus sinensis in the province of Corrientes, Argentina, in two plots (AM1 irrigated and AM2 unirrigated) of 0.82 hectares each. Spiders were collected monthly by using pitfall traps, hand capture, agitation of foliage and sieving of soil litter. A total of 7 174 specimens were collected (33 families, 44 genera and 200 species/morphospecies). The AM1 recorded 3 811 individuals (33 families, 179 species/morphospecies) and AM2 3 363 individuals (31 families, 174 species/morphospecies). November, December and January showed the highest abundance in both plots. A total of 70% of collected spiders were juveniles. Eight families were the most abundant and represented 75% of spiders collected in both plots, the largest being Lycosidae. We identified eight guilds in both plots, for which the ground runners resulted the most abundant (AM1 n=1341, s=39, n=999 AM2, s=33), followed by orb weavers (AM1 n=637, s=36; AM2 n=552, s=33), the stalkers (AM1 n=471, s=43, AM2 n=453, s=47) and the space webbuilders (AM1 n=446, s=23; AM2 n=342, s=25). The analysis of alpha diversity in both plots (AM1H'=4.161, J'=0.802; AM2 H'=4.184, J'=0.811) showed no significant differences (t=1.083 p=0.279). The linear dependences model was the one with the best fit results, where the species observed were more than estimated. Clench model estimated 90.9% of the spiders observed in the unit with irrigation and 90.6% in the unit without irrigation.

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Domestic and peridomestic triatomine colonization, T. infestans infection rate and human seropositives to Trypanosoma cruzi in rural areas of Empedrado Department, Corrientes, Argentina, were carried out. Methods used in order to search the triatomines, to determine them systematically, to obtain their infection rates and the human seropositives, were the same applied in a previous report. From 100 households characterized, 53.0% had mud walls, laminated zinc or cardboard combined with other elements were used in 37.5% of the roofs, and 83.0% had earthen floors. Presence of domestic animais sleeping inside houses was detected in 91.0% of human dwellings. Domestic infestation by T. infestans was 29.0% and 1.0% by T. sordida. Other T. infestans entomological indexes recorded were: natural infection index = 23, colonization index = 75 and dispersion index = 54,5. T. sordida was found in 12.1% of peridomestic structures while T. infestans was detected in 2.4%. General prevalence from 298 human sera analized by Indirect Hemagglutination and Indirect Immunofluorescence Antibody Tests, was 32.2%. A high percentage of positive serology (23.7%) was found among 0-10 years old, wich represent the age group of higher transmission risk.

Se llevõ a cabo un estúdio epidemiológicopara obtener u n p a n o ra m a general de la transmisión doméstica del T ry p an o so m a cru zi en ãreas rurales dei Departamento San Miguel, Conientes, Argentina. Se investigaron 100 viviendas precarias, 50,0% de las mismas resultó infestado p o r T riatom a infestans y 1,0% p o r T. sórd ida, citãndose p o r prim era vez para la provinda de Comentes la colonización domiciliaria de esta especie. El 23,1% de T. infestans estaba infectado p o r T. cru zi. La seroprevalencia de 3 8 8 pacientes analizados p o r hemaglutinacíôn indirecta e inmunofluorescencia indirecta f u e 23,4% , destacãndose el alto índice (12,9% ) constatado en menores de 10 anos. Losporcentajes de seropositividad aumentaron con la edad, alcanzãndose 50,0% d e infectados en tre los 3 1 -4 0 anos. La infestaciõn dom éstica por'Y . in f e s ta n s , la prevalencia hum ana de seropositivos a lT. cruzi y las condiciones dep reca ried a d en que se desenvuelve la vida de los pobladores revelan la vigência de la endem ia chagãsica en el área estudiada.Palabras-claves: Triatominos. Infestaciõn. T. cru zi. Seroprevalencia. Conientes.