Incipient colonisation of Lutzomyia longipalpis in the city of Resistencia,province of Chaco,Argentina (2010-2012)

Lutzomyia longipalpis was recorded for the first time in Argentina in 2004, in the province of Formosa. In the following years, the vector spread to the south and west in the country and was recorded in the province of Chaco in 2010. From November 2010-May 2012, captures of Phlebotominae were made in the city of Resistencia and its surroundings, to monitor the spread and possible colonisation of Lu. longipalpis in the province of Chaco. In this monitoring, Lu. longipalpis was absent in urban sampling sites and its presence was restricted to Barrio de los Pescadores. This suggests that the incipient colonisation observed in 2010 was not followed by continuous installation of vector populations and expansion of their spatial distribution as in other urban centres of Argentina.     

The peri-urban interface and house infestation with Triatoma infestans in the Argentine Chaco: an underreported process?

Peri-urban infestations with triatomine bugs, their sources and their dynamics have rarely been investigated. Here, we corroborated the reported occurrence of Triatoma infestans in a peri-urban area and in neighbouring rural houses in Pampa del Indio, in the Argentine Chaco, and identified its putative sources using spatial analysis and demographic questionnaires. Peri-urban householders reported that 10% of their premises had triatomines, whereas T. infestans was collected by timed manual searches or community-based surveillance in only nine (3%) houses. Trypanosoma cruzi-infected T. infestans and Triatoma sordida were collected indoors only in peri-urban houses and were infected with TcV and TcI, respectively. The triatomines fed on chickens, cats and humans. Peri-urban infestations were most frequent in a squatter settlement and particularly within the recently built mud houses of rural immigrants, with large-sized households, more dogs and cats and more crowding. Several of the observed infestations were most likely associated with passive bug transport from other sources and with active bug dispersal from neighbouring foci. Thus, the households in the squatter settlement were at a greater risk of bug invasion and colonisation. In sum, the incipient process of domestic colonisation and transmission, along with persistent rural-to-urban migratory flows and unplanned urbanisation, indicate the need for active vector surveillance and control actions at the peri-urban interface of the Gran Chaco.     

Long-term impact of a ten-year intervention program on human and canine Trypanosoma cruzi infection in the Argentine Chaco

BackgroundInterruption of domestic vector-borne transmission of Trypanosoma cruzi is still an unmet goal in several American countries. In 2007 we launched a long-term intervention program aimed to suppress house infestation with the main domestic vector in southern South America (Triatoma infestans) and domestic transmission in Pampa del Indio, a resource-constrained, hyperendemic municipality with 1446 rural houses inhabited by Creole and indigenous people, in the Argentine Chaco ecoregion. Here, we assessed whether the 10-year insecticide-based program combined with community mobilization blocked vector-borne domestic transmission of T. cruzi to humans and dogs.MethodsWe carried out two municipality-wide, cross-sectional serosurveys of humans and dogs (considered sentinel animals) during 2016–2017 to compare with baseline data. We used a risk-stratified random sampling design to select 273 study houses; 410 people from 180 households and 492 dogs from 151 houses were examined for antibodies to T. cruzi using at least two serological methods.ResultsThe seroprevalence of T. cruzi in children aged <16 years was 2.5% in 2017 (i.e., 4- to 11-fold lower than before interventions). The mean annual force of child infection (λ) sharply decreased from 2.18 to 0.34 per 100 person-years in 2017. One of 102 children born after interventions was seropositive for T. cruzi; he had lifetime residence in an apparently uninfested house, no outside travel history, and his mother was T. cruzi-seropositive. No incident case was detected among 114 seronegative people of all ages re-examined serologically. Dog seroprevalence was 3.05%. Among native dogs, λ in 2016 (1.21 per 100 dog-years) was 5 times lower than at program onset. Six native adult dogs born after interventions and with stable lifetime residence were T. cruzi-seropositive: three had exposure to T. infestans at their houses and one was an incident case.ConclusionsThese results support the interruption of vector-borne transmission of T. cruzi to humans in rural Pampa del Indio. Congenital transmission was the most likely source of the only seropositive child born after interventions. Residual transmission to dogs was likely related to transient infestations and other transmission routes. Sustained vector control supplemented with human chemotherapy can lead to a substantial reduction of Chagas disease transmission in the Argentine Chaco.     

Echinoderms (Echinodermata) of the Mexican Caribbean

A systematic list of the echinoderms of the Mexican Caribbean based on museum specimens of the Colección Nacional de Equinodermos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México and the National Museum of Natural History, Smithsonian Institution, Washington, D.C. is presented. This list reveals an important echinoderm biodiversity in the Mexican Caribbean, where five of the six echinoderm classes are represented. A total of 178 echinoderm species is recorded, distributed in 113 genera, 51 families and 22 orders. 30 new records for the Mexican Caribbean are presents: Crínoidea (three), Asteroidea (two), Ophiuroidea (eleven), Echinoidea (one), Holothuroidea (thirteen).     

Ecological and Sociodemographic Determinants of House Infestation by Triatoma infestans in Indigenous Communities of the Argentine Chaco

BackgroundThe Gran Chaco ecoregion, a hotspot for Chagas and other neglected tropical diseases, is home to >20 indigenous peoples. Our objective was to identify the main ecological and sociodemographic determinants of house infestation and abundance of Triatoma infestans in traditional Qom populations including a Creole minority in Pampa del Indio, northeastern Argentina.MethodsA cross-sectional survey determined house infestation by timed-manual searches with a dislodging aerosol in 386 inhabited houses and administered questionnaires on selected variables before full-coverage insecticide spraying and annual vector surveillance. We fitted generalized linear models to two global models of domestic infestation and bug abundance, and estimated coefficients via multimodel inference with model averaging.

Principal Findings

Most Qom households were larger and lived in small-sized, recently-built, precarious houses with fewer peridomestic structures, and fewer livestock and poultry than Creoles’. Qom households had lower educational level and unexpectedly high residential mobility. House infestation (31.9%) was much lower than expected from lack of recent insecticide spraying campaigns and was spatially aggregated. Nearly half of the infested houses examined had infected vectors. Qom households had higher prevalence of domestic infestation (29.2%) than Creoles’ (10.0%), although there is large uncertainty around the adjusted OR. Factors with high relative importance for domestic infestation and/or bug abundance were refuge availability, distance to the nearest infested house, domestic insecticide use, indoor presence of poultry, residential overcrowding, and household educational level.

Conclusions and Significance

Our study highlights the importance of sociodemographic determinants of domestic infestation such as overcrowding, education and proximity to the nearest infested house, and corroborates the role of refuge availability, domestic use of insecticides and household size. These factors may be used for designing improved interventions for sustainable disease control and risk stratification. Housing instability, household mobility and migration patterns are key to understanding the process of house (re)infestation in the Gran Chaco.     

Activity of Lutzomyia pseudolongipalpis and L. longipalpis s.l. (Diptera: Psychodidae) in Venezuela

The nocturnal activity of the phlebotomine sandfly Lutzomyia pseudolongipalpis and two populations of L. longipalpis s.l. from different American visceral leishmaniasis foci in Venezuela was studied using collection bottle rotator traps. The activity of L. pseudolongipalpis from Lara State was continuous throughout the night, while that of L. longipalpis s.l. from El Layero, Guárico State and from Santa Ana del Valle, Margarita Island, was greatest before 23:00 h. The activity of sandflies of both populations and sexes steadily decreased thereafter. These different patterns seem to correlate with genetic data that indicate the presence in Venezuela of at least two sibling species in the L. longipalpis complex. The advantages of the bottle rotator trap for this type of study are discussed.     

Distribution and 16S rDNA sequences of <Emphasis Type="Italic">Argas monachus</Emphasis> (Acari: Argasidae), a soft tick parasite of <Emphasis Type="Italic">Myiopsitta monachus</Emphasis> (Aves: Psittacidae)

Specimens of Argas monachus Keirans et al. were collected from Myiopsitta monachus nests in 42 localities in Argentina and Paraguay from 2006 to 2010. A list of localities where this tick has been found is presented. 16S rDNA sequences of specimens of A. monachus from different localities were compared to confirm whether they belong to the same specific taxon. Argas monachus is present in the phytogeographic provinces of Chaco, Espinal, and Monte, but not in the Pampa (all from de Chaco Domain) where the host is well distributed. No differences were found among 16S rDNA sequences of geographically distant specimens.     

Domestic host availability modifies human-triatomine contact and host shifts of the Chagas disease vector Triatoma infestans in the humid Argentine Chaco

Domestic animals may affect human-vector contact and parasite transmission rates. We investigated the relationships between host-feeding choices, site-specific host availability, bug nutritional status, stage and abundance of Triatoma infestans Klug (Heteroptera: Reduviidae) in rural houses of Pampa del Indio during spring. We identified the bloodmeal sources of 865 triatomines collected in 70 sites from four main ecotopes. The main sources in domiciles were human (65.9%), chicken (23.4%) and dog (22.4%); dog (64.4%, 35.3%) and chicken (33.1%, 75.4%) in kitchens and storerooms, respectively; and chicken (94.7%) in chicken coops. Using random-intercept logistic regression clustered by domicile, the fraction of human-fed triatomines strongly decreased with increasing proportions of chicken- and dog-fed bugs, dropping from 96.4% when no chicken or dog slept indoors at night to 59.4% when both did. The fraction of dog-fed bugs significantly decreased with increasing human and chicken blood indices, and marginally increased with an indoor-resting dog. Mixed blood meals occurred 3.62 times more often when a chicken or a dog slept indoors. Host blood source did not affect mean body weight adjusted for body length and bug stage. Indoor-resting chickens and dogs greatly modified human-bug contact rates, and may be targeted with long-lasting systemic insecticides to suppress infestation.     

Species composition and seasonal abundance of sandflies (Diptera: Psychodidae: Phlebotominae) in coffee agroecosystems

The composition and seasonal occurrence of sandflies were investigated in coffee agroecosystems in the Soconusco region of Chiapas, Mexico. Insect sampling was performed on three plantations located at different altitudes: Finca Guadalupe Zajú [1,000 m above sea level (a.s.l.)], Finca Argovia (613 m a.s.l.) and Teotihuacán del Valle (429 m a.s.l.). Sandflies were sampled monthly from August 2007-July 2008 using three sampling methods: Shannon traps, CDC miniature light traps and Disney traps. Sampling was conducted for 3 h during three consecutive nights, beginning at sunset. A total of 4,387 sandflies were collected during the course of the study: 2,718 individuals in Finca Guadalupe Zajú, 605 in Finca Argovia and 1,064 in Teotihuacán del Valle. The Shannon traps captured 94.3% of the total sandflies, while the CDC light traps and Disney traps captured 4.9% and 0.8%, respectively. More females than males were collected at all sites. While the number of sandflies captured was positively correlated with temperature and relative humidity, a negative correlation was observed between sandfly numbers and rainfall. Five species of sandflies were captured: Lutzomyia cruciata , Lutzomyia texana , Lutzomyia ovallesi , Lutzomyia cratifer / undulata and Brumptomyia sp. Lu. cruciata , constituting 98.8% of the total, was the most abundant species. None of the captured sandflies was infected with Leishmania spp.     

First record of Phlebotomine sandflies (Diptera: Psychodidae) in the Comoros Archipelago with description of Sergentomyia (Vattieromyia) pessoni n. sp. and S. (Rondanomyia) goodmani comorensis n. ssp

No Phlebotomine sandflies had ever been reported in the Comoros Archipelago, including the three islands of the Republic of the Union of Comoros (Grande Comore, Mohéli and Anjouan) and the French oversea department of Mayotte. During three field surveys carried out in 2003, 2007 and 2011, we provided the first record of Phlebotomine sandflies in this area. A total of 85 specimens belonging to three species were caught: a new species S. (Vattieromyia) pessoni n. sp. (two females from Grande Comore), a new subspecies of Sergentomyia (Rondanomyia) goodmani (80 specimens from Grande Comore and one from Anjouan) and Grassomyia sp. (two females from Mohéli). The individualisation of these taxa was inferred both from morphological criteria and sequencing of a part of the cytochrome b of the mitochondrial DNA. These taxa are closely related to Malagasy sandflies.     

Natural breeding places of phlebotomine sandflies

Methods of finding larvae and pupae of phlebotomine sandflies (Diptera: Psychodidae) are described and the known types of breeding sites used by sandflies are listed. Three ways of detecting sandfly breeding places are the use of emergence traps placed over potential sources to catch newly emerged adult sandflies; flotation of larvae and pupae from soil, etc., and desiccation of media to drive out the larvae. Even so, remarkably little information is available on the ecology of the developmental stages of sandflies, despite their importance as vectors of Leishmania, Bartonella and phleboviruses affecting humans and other vertebrates in warmers parts of the world. Regarding the proven or suspected vectors of leishmaniases, information on breeding sites is available for only 15 out of 29 species of sandflies involved in the Old World and 12 out of 44 species of sandflies involved in the Americas, representing approximately 3% of the known species of Phlebotominae. Ecotopes occupied by immature phlebotomines are usually organically rich moist soils, such as the rain forest floor (Lutzomyia intermedia, Lu. umbratilis, Lu. whitmani in the Amazon; Lu. gomezi, Lu. panamensis, Lu. trapidoi in Panama), or contaminated soil of animal shelters (Lu. longipalpis s.l. in South America, Phlebotomus argentipes in India; P. chinensis in China; P. ariasi, P. perfiliewi, P. perniciosus in Europe). Developmental stages of some species (P. langeroni and P. martini in Africa; P. papatasi in Eurasia; Lu. longipalpis s.l. in South America), have been found in a wide range of ecotopes, and many species of sandflies employ rodent burrows as breeding sites, although the importance of this niche is unclear. Larvae of some phlebotomines have been found in what appear to be specialized niches such as Lu. ovallesi on buttress roots of trees in Panama; P. celiae in termite hills in Kenya; P. longipes and P. pedifer in caves and among rocks in East Africa. Old World species found as immatures in the earthen floor of human habitations include P. argentipes, P. chinensis, P. martini and P. papatasi. Much more information on sandfly breeding sites is required to facilitate their control by source reduction.     

Where do these bugs come from? Phenotypic structure of Triatoma infestans populations after control interventions in the Argentine Chaco

House re-invasion by native triatomines after insecticide-based control campaigns represents a major threat for Chagas disease vector control. We conducted a longitudinal intervention study in a rural section (Area III, 407 houses) of Pampa del Indio, northeastern Argentina, and used wing geometric morphometry to compare pre-spray and post-spray (re-infestant bugs) Triatoma infestans populations. The community-wide spraying with pyrethroids reduced the prevalence of house infestation by T. infestans from 31.9% to < 1% during a four-year follow-up, unlike our previous studies in the neighbouring Area I. Two groups of bug collection sites differing in wing shape variables before interventions (including 221 adults from 11 domiciles) were used as a reference for assigning 44 post-spray adults. Wing shape variables from post-spray, high-density bug colonies and pre-spray groups were significantly different, suggesting that re-infestant insects had an external origin. Insects from one house differed strongly in wing shape variables from all other specimens. A further comparison between insects from both areas supported the existence of independent re-infestation processes within the same district. These results point to local heterogeneities in house re-infestation dynamics and emphasise the need to expand the geographic coverage of vector surveillance and control operations to the affected region.     

Native arbuscular mycorrhizal fungi in the Yungas forests, Argentina

The arbuscular mycorrhizal fungal (AMF) communities from the Yungas forests of Argentina were studied. The AMF species present in the rhizosphere of some dominant native plants (one tree: Alnus acuminata; three herbaceous species: Duchesnea indica, Oxalis conorrhiza, Trifolium aff. repens; and one shrub: Sambucus peruviana) from two sites (Quebrada del Portugués and Narváez Range) of the Yungas forests were isolated, identified and quantified during the four seasons of the year. Twenty-two AMF morphotaxa were found. Spore density of some AMF species at each site varied among seasons. The genera that most contributed to the biodiversity index were Acaulospora for Quebrada del Portugués and Glomus for Narváez Range. High diversity values were observed in the Yungas forests, particularly in the spring (rainy season). We concluded AMF differed in species composition and seasonal sporulation dynamics in the Yungas forests.     

Molecular characterization of the Andean blackberry, Rubus glaucus, using SSR markers

The species Rubus glaucus, also known as the Andean or "Castilla" blackberry, is one of nine edible species of this genus that grow naturally in Central and South America. In Colombia, this species is the most important of all Rubus species for agricultural and commercial purposes. We used 20 SSRs developed for other Rubus species to characterize 44 Colombian R. glaucus genotypes, collected from eight different departments, and to look for molecular differences between thornless and thorny cultivated blackberries. Eighty-two bands were obtained from 28 loci. The genotypes were classified into eight populations, corresponding to collection sites. The mean number of polymorphic alleles per locus in all populations and genotypes ranged from 1.857 to 2.393. Samples collected from Valle del Cauca, Quindío, Caldas, and Risaralda departments had the highest heterozygosity values. The finding of exclusive bands from R. glaucus genotypes from Valle del Cauca, Quindío, and Caldas demonstrates genetic and molecular differentiation between thorny and thornless Andean blackberries.     

Obrieniolus, a new monotypic genus of Naupactini (Coleoptera, Curculionidae, Entiminae) from the Peruvian Andes and its phylogenetic placement

A new monotypic genus of Naupactini (Coleoptera: Curculionidae), Obrieniolus del Río is described based on the new species Obrieniolus robustus del Río, endemic to Peru. This genus is easily recognized by the black, denuded and shiny integument, with imbricate microsculpture and the rounded body, with short, cordiform and moderately convex elytra. According to a cladistic analysis based on 69 continuous and discrete morphological characters, the new genus is the sister taxon of a group formed by Amitrus Schoenherr, Trichocyphus Heller, Amphideritus Schoenherr, Asymmathetes Wibmer & O'Brien and Galapaganus Lanteri. The paper includes habitus photographs, line drawings of genitalia, mouthparts, and other external features of taxonomic value, and a dichotomous key to the genera of Naupactini distributed in the South American Transition Zone.     

Diameter-weight relationship and chromatic proportion of the sea urchin Lytechinus variegatus (Echinoidea: Toxopneustidae) in the islands of Margarita and Cubagua, Venezuela

In Margarita and Cabagua Islands, Venezuela, the sea urchin Lytechinus variegatus is consumed as food but few studies concern its biology. Between January 1999 and September 2000, 25 localities of Margarita and Cubagua islands we visited to determinate the relationship between diameter and weight of living urchins according to their coloration green or white. A total of 5 066 urchins (3 421 captured in Margarita and 1 645 in Cubagua) were measured. There is no significant difference in the weight-diameter relations of green or white sea urchins of both islands. The weight-diameter equation is P = 0.00246 D252. Utilizing a quadrant (0.5 x 0.5 m) monthly samples of urchins living in a 2 m2 of surface were taken to estimate the abundance of the specimens according their color (N = 6 948 urchins). The green urchins were more abundant than the white urchins, in a 3:2 proportion.     

A new species of Curimata (Characiformes,Curimatidae) from Paraná system,in resistencia,Argentine

A new curimatid fish, Curimata gnaca, from two localities, both in the neighborhoods of Resistencia, Chaco Province, Argentine, is described. The species is distinguished from other curimatids by the position of the mouth, a low number of perforated scales in lateral line, scales with straight margin on sides of body and long pectoral fins. The new species is placed in the genus Curimata until the problems within it will be solved.     

Studies on the behaviour and control of phlebotomine sandflies using experimental houses

Programmes for the control of phlebotomine sandflies (Diptera: Psychodidae), the vectors of leishmaniases, mainly target adults because larval breeding sites are generally unknown or inaccessible. To determine how blood‐questing sandfly females enter homes and to develop means for their control, an experimental house (EH) was constructed in a village endemic for cutaneous leishmaniasis. Initially, carbon dioxide (CO₂)‐baited suction traps were installed inside the EH to attract and capture sandflies. For other experiments, the windows of the EH were fitted with CO₂‐baited window entrance traps (WETs) that allow each window to be considered as a separate unit. The majority of captures inside the EH and in WETs consisted of Phlebotomus sergenti, a species that enters inhabited houses relatively infrequently. Analyses of collections in WETs and in sticky traps on external walls showed that sandflies entered windows having landed previously on the wall below or either side of the window. Shelves constructed below windows significantly reduced the numbers of sandflies that entered both the EH and inhabited houses. The lining of internal walls with insecticide‐impregnated fabric significantly increased mortality rates of sandflies captured inside the EH. To reduce the biting burden imposed by phlebotomine sandflies, several control measures must be integrated and sustained.     

Mitochondrial DNA haplogroups in Amerindian populations from the Gran Chaco.

Mitochondrial DNA from 141 individuals was typed for diagnostic restriction sites and the 9-bp region V deletion to examine the distribution of the founding mtDNA lineage haplotypes in three Amerindian populations (Mataco, Toba, and Pilagá) who currently inhabit the Argentinian part of the Gran Chaco. All four lineages were identified in the three tribes and four population samples studied. Disregarding ethnic or geographic origin, haplogroups B and D exhibit high incidence among the Gran Chaco inhabitants, whereas haplogroups A and C are present in a lower frequency. Three individuals possess none of the characteristic markers and, therefore, could not be assigned to one of those lineages. A neighbor-joining representation of F(ST) distances reflects the current geographic location of the populations, and this also corresponds to their historic distribution. After separating South America into four major regions (Tropical Forest, Andes, Gran Chaco, and Patagonia-Tierra del Fuego), the Gran Chaco populations present the highest average intragroup variability (Hs = 0.64) as well as the lowest intergroup diversity (G(')(ST) = 0.06). These findings suggest high levels of gene flow among the Chaco tribes, as well as with neighbor populations from outside the region.