Abstract. Chagas disease represents a major public health concern in most of Latin America, and its control is currently based on vector control and blood bank screening. We investigated the geographic distribution and seasonal variations in triatomine populations in the Yucatan peninsula of Mexico to obtain entomologic data for the optimization of potential control programs. We collected domiciliated and peri-domiciliated Triatoma dimidiata from 115 houses in 23 villages distributed throughout most of the peninsula. A high abundance of bugs was observed in the northern part of the peninsula, indicating a prioritary area for vector control. Part of this distribution could be attributed to the type of vegetation. We also documented strong seasonal variations in T. dimidiata populations, with a higher abundance during the hot and dry season in April-June. These variations, associated with reduced year-round colonization of houses and the analysis of developmental stage structure, suggest that flying adults seasonally invading houses may play a larger role than domiciliated bugs in transmission of Trypanosoma cruzi to humans. The importance of this transmission dynamics may not be limited to the Yucatan peninsula, but may be a general mechanism contributing to natural transmission that should be taken into account in other regions for the design and optimization of control strategies.

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Host use by vectors is important in understanding the transmission of zoonotic diseases, which can affect humans, wildlife and domestic animals. Here, a synthesis of host exploitation patterns by kissing-bugs, vectors of Chagas disease, is presented. For this synthesis, an extensive literature review restricted to feeding sources analysed by precipitin tests was conducted. Modern tools from community ecology and multivariate statistics were used to determine patterns of segregation in host use. Rather than innate preferences for host species, host use by kissing-bugs is influenced by the habitats they colonise. One of the major limitations of studies on kissing-bug foraging has been the exclusive focus on the dominant vector species. We propose that expanding foraging studies to consider the community of vectors will substantially increase the understanding of Chagas disease transmission ecology. Our results indicate that host accessibility is a major factor that shapes the blood-foraging patterns of kissing-bugs. Therefore, from an applied perspective, measures that are directed at disrupting the contact between humans and kissing-bugs, such as housing improvement, are among the most desirable strategies for Chagas disease control.Key words: foraging -null models -diet analysis -multivariate statistics -Chagas disease -niche breadth Blood-feeding patterns of triatomines • Jorge Eduardo Rabinovich et al. 480 Several aspects of feeding-related behaviour in triatomines have also been well studied. Such aspects include feeding preferences (Quintal & Polanco 1977), avoidance of excessive warming during feeding (Lazzari et al. 2009), importance of nutritional status in flight initiation and dispersal (Lehane & Schofield 1982, Lehane et al. 1992, Noireau & Dujardin 2001, Emmanuelle-Machado et al. 2002, Ceballos et al. 2005, avoidance of predators during feeding (Bodin et al. 2009a, b), frequency and size of the blood intake (Maddrell 1963, Wood 1976, Montenegro & Pasina 1984, Maifrino et al. 1986, Pietrokovsky et al. 1996, Pereira et al. 1998, control of meal size (Bennet-Clark 1963b) and the relationship between feeding and defecation patterns as well as other aspects of feeding with epidemiological importance (Wood 1951, Dias 1956, Zeledón et al. 1970, 1977, Da Rocha e Silva et al. 1979, Crocco & Catalá 1996, Kollien & Schaub 1998, Zabala & D' Antonio 1988, Braga & Lima 1999, Aldana et al. 2001, Emmanuelle-Machado et al. 2002, Nattero et al. 2002, Almeida et al. 2003, Arévalo et al. 2007, Rodriguez et al. 2008, Klotz et al. 2009).Studies have been conducted on the relationship between the impacts of the triatomine feeding process and demographic parameters (Davies 1990, Malo et al. 1993, Emmanuelle-Machado et al. 2002, mortality and fecundity (Goodchild 1955, Hays 1965, Regis 1977, Patterson 1979, Catalá de Montenegro 1989, Braga et al. 1998, Braga & Lima 2001, Davey 2007, development time (Martinez-Ibarra et al. 2003, Martinez-Ibarra & Novelo-López 2004, resistance to starvation (Gajardo Tobar 1952,...

Chagas disease, caused by the parasite Trypanosoma cruzi , is the most important vector-borne disease in Latin America. The vectors are insects belonging to the Triatominae (Hemiptera, Reduviidae), and are widely distributed in the Americas. Here, we assess the implications of climatic projections for 2050 on the geographical footprint of two of the main Chagas disease vectors: Rhodnius prolixus (tropical species) and Triatoma infestans (temperate species). We estimated the epidemiological implications of current to future transitions in the climatic niche in terms of changes in the force of infection (FOI) on the rural population of two countries: Venezuela (tropical) and Argentina (temperate). The climatic projections for 2050 showed heterogeneous impact on the climatic niches of both vector species, with a decreasing trend of suitability of areas that are currently at high-to-moderate transmission risk. Consequently, climatic projections affected differently the FOI for Chagas disease in Venezuela and Argentina. Despite the heterogeneous results, our main conclusions point out a decreasing trend in the number of new cases of Tr. cruzi human infections per year between current and future conditions using a climatic niche approach.

Trypanosoma cruzi, the causative agent of Chagas disease, is transmitted to mammals - including humans - by insect vectors of the subfamily Triatominae. We present the results of a compilation of triatomine occurrence and complementary ecological data that represents the most complete, integrated and updated database (DataTri) available on triatomine species at a continental scale. This database was assembled by collecting the records of triatomine species published from 1904 to 2017, spanning all American countries with triatomine presence. A total of 21815 georeferenced records were obtained from published literature, personal fieldwork and data provided by colleagues. The data compiled includes 24 American countries, 14 genera and 135 species. From a taxonomic perspective, 67.33% of the records correspond to the genus Triatoma, 20.81% to Panstrongylus, 9.01% to Rhodnius and the remaining 2.85% are distributed among the other 11 triatomine genera. We encourage using DataTri information in various areas, especially to improve knowledge of the geographical distribution of triatomine species and its variations in time.

Assessing the sustainability of complex development processes requires multi-causal and integrated analyses. We develop a system-based methodology, rooted Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.in interdisciplinary discussion and consensus building between 15 experts, to construct a multi-causal diagram which examines the sustainability of the Argentine Pampaś process of agriculturization. The resulting diagram includes 25 factors and provides a big-picture of the multiple dimensions and interrelations affecting sustainability. According to this examination, the increasing concentration of production and the incorporation of technological innovations, triggered by economic and institutional factors, are the cause of environmental distresses and social changes, whose consequences for sustainability are still highly disputed. Nevertheless, the symptoms of both environmental and social unsustainability are more evident in the case of the extraPampean regions than in the Pampas. This suggests that the Pampean agriculture model should not be transferred to these regions without substantial modifications. The experts did not reach consensus on whether the agriculturization process is overall sustainable or unsustainable. Lack of consensus revolved mainly around opposing perspectives regarding the significance of the threats to environmental sustainability. The magnitude of socio-distributive unbalance and loss of rural jobs were also contentious. Yet, the paper shows how the exercise of building a joint causal diagram was undoubtedly helpful for linking piece-meal disciplinary facts, brought in from all fronts, into a comprehensive and coherent picture.

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Chagas disease is one of the most important diseases in Latin America. Insecticides have been sprayed to control domiciliated vectors. However, some triatomine species are not strictly domiciliated, and the transmission risk posed by immigrants is identified as a major challenge. The design of new control strategies requires disentangling the importance of demography and immigration in vector occurrence inside houses. Using a population dynamics model, we confirmed that dispersal can explain satisfactorily the domestic abundance of Triatoma dimidiata in Yucatan, Mexico. A surprisingly low fecundity was also required (no more than one to two female offspring per female per trimester). A wide range of survival probabilities was possible, although the best fit was obtained for a very low immature survival (< or = 0.01/trimester). Our model predicted that domestic populations are not sustainable, and up to 90% of the individuals found in houses are immigrants. We discuss the potential of different strategies to control the transmission of Chagas disease by non-domiciliated vectors.