Smoke of Capsicum baccatum L. var. baccatum (Solanaceae) repels nymphs of triatoma infestans (Klug) (Hemiptera: Reduviidae) / Humo de capsicum baccatum L. var. baccatum (Solanaceae) repele las ninfas de Triatoma infestans (Klug) (Hemiptera: Reduviidae)

Control of the Chagas disease vector, Triatoma infestans (Klug) (Hemiptera: Reduviidae) with synthetic pesticides in Bolivia has become increasingly inefficient due to the development of resistance in the insects. In the Chaco region of Bolivia, guaraní populations have approached the problem by fumigating their houses with the smoke of native plants. Through interviews and field work with local guides, the main plant used by the guaraníes was collected and later identified as Capsicum baccatumL. var. baccatum (Solanaceae). In choice bioassays, filter papers exposed to the smoke of the plant repelled nymphs of T. infestans. Activity remained significant after storing the exposed filter papers for 9 days. Chemical analysis of smoke and literature data suggested that capsaicinoids present in the smoke were responsible for the repellent effect. The data presented provide a rationale for the use of C. baccatumvar. baccatumto control the Chagas vector bythe guaraní populations.

El control del vector de la enfermedad de Chagas, Triatoma infestans (Klug) (Hemiptera: Reduviidae) con plaguicidas sintéticos en Bolivia se ha vuelto cada vez más ineficiente debido al desarrollo de resistencias en los insectos. En la región del Chaco de Bolivia, las poblaciones guaraníes han abordado el problema fumigando sus casas con el humo de las plantas nativas. A través de entrevistas y trabajo de campo con guías locales, se recogió la principal planta utilizada por los guaraníes y posteriormente se identificó como Capsicum baccatumL. var. baccatum (Solanaceae). En bioensayos selectos, los papeles de filtro expuestos al humo de la planta repelieron a las ninfas de T. infestans. La actividad siguió siendo significativa después de almacenar los papeles de filtro expuestos durante 9 días. El análisis químico del humo y los datos de la literatura sugieren que los capsaicinoides presentes en el humo eran responsables del efecto repelente. Los datos presentados proporcionan una justificación para el uso de C. baccatum var. baccatum para el control del vector Chagas por las poblaciones guaraníes.

Transcriptomic modulation in response to an intoxication with deltamethrin in a population of Triatoma infestans with low resistance to pyrethroids

Background Triatoma infestans is the main vector of Chagas disease in the Southern Cone. The resistance to pyrethroid insecticides developed by populations of this species impairs the effectiveness of vector control campaigns in wide regions of Argentina. The study of the global transcriptomic response to pyrethroid insecticides is important to deepen the knowledge about detoxification in triatomines. Methodology and findings We used RNA-Seq to explore the early transcriptomic response after intoxication with deltamethrin in a population of T. infestans which presents low resistance to pyrethroids. We were able to assemble a complete transcriptome of this vector and found evidence of differentially expressed genes belonging to diverse families such as chemosensory and odorantbinding proteins, ABC transporters and heat-shock proteins. Moreover, genes related to transcription and translation, energetic metabolism and cuticle rearrangements were also modulated. Finally, we characterized the repertoire of previously uncharacterized detoxification-related gene families in T. infestans and Rhodnius prolixus. Conclusions and significance Our work contributes to the understanding of the detoxification response in vectors of Chagas disease. Given the absence of an annotated genome from T. infestans, the analysis presented here constitutes a resource for molecular and physiological studies in this species. The results increase the knowledge on detoxification processes in vectors of Chagas disease, and provide relevant information to explore undescribed potential insecticide resistance mechanisms in populations of these insects.

Cytochrome P450 Genes of the CYP4 Clan and Pyrethroid Resistance in Chagas Disease Vectors

he chemical control of Triatoma infestans, the major Chagas disease vector in southern South America, has been threatened in the last years by the emergence of pyrethroid-resistant bug populations. As an alternative approach, the efficacy of the entomopathogenic fungus Beauveria bassiana to control T. infestans populations (regardless their pyrethroid susceptibility) has been demonstrated. Growing research efforts on the interaction between T. infestans and B. bassiana by molecular, ecological, biochemical and behavioral traits has allowed framing such interaction as an evolutionary arms race. This review will focus on the relationships established in this particular host-pathogen system, compiling available data on the relevance of fungal pathogenesis, insect behavior, population dynamics and human intervention to favor fungal dissemination in bug populations. The current snapshot shows the fungus ahead in the evolutionary arms race and predicts a promissory landscape for the biological control of Chagas disease vectors.

Sustainable, integrated control of native vectors: The case of Chagas disease in Central America

Despite successes in reducing transmission, Chagas disease (American trypanosomiasis) remains the greatest economic burden of any parasitic disease in Latin America afflicting mostly the poor and further contributing to poverty. We review a long-term (2001-2022), integrated Ecohealth approach that addresses sustainable development goals to reduce risk of Chagas transmission by the main native vector in Central America, Triatoma dimidiata, s.l. The basis of the Ecohealth intervention was the identification of the risk factors for house infestation, an understanding of and collaboration with local communities, and genetic and proteomic studies that revealed the epidemiology and mechanisms of the rapid reinfestation seen following insecticide application. We review the development of this approach from a pilot project in two Guatemalan villages, to an expanded initiative across three countries with vastly different ecology, cultures, and municipal organization, and finally development of a multi-institutional, large-scale project to develop a strategy to tackle the remaining hot spots in Central America. This integrated Ecohealth approach resulted in reduced risk of transmission as measured by a sustained decrease in house infestation without further use of insecticides, a reduction in vectors with human blood meals and the Chagas parasite, as well as other health and economic benefits. We discuss lessons learned and how this approach could be applied to other vector-borne diseases.

Controle de populações de Triatoma infestans resistentes a piretróides, principal vetor do Trypanosoma cruzi, por meio do tratamento de cães com fluralaner no Chaco argentino / Control de poblaciones de Triatoma infestans resistente a piretroides, principal vector de Trypanosoma cruzi, mediante tratamiento de plantas con fluralaner en el Chaco argentino / Control of populations of pyrethroid-resistant Triatoma infestans, the main vector of Trypanosoma cruzi, through treatment of plants with fluralaner in the Argentine Chaco

We assessed whether fluralaner administered to outbred healthy dogs reduced or supressed site infestation and abundance of pyrethroid-resistant populations of Triatoma infestans Klug (Heteroptera: Reduviidae). We conducted a placebo-controlled before-and-after efficacy trial in 28 infested sites in Castelli (Argentine Chaco) over 10 months. All 72 dogs initially present received either an oral dose of fluralaner (treated group) or placebo (control group) at month 0 posttreatment (MPT). Preliminary results justified treating all 38 control-house dogs with fluralaner 1 month later, and 71 of 78 existing dogs at 7 MPT. Site-level infestation and triatomine abundance were evaluated using timed manual searches with a dislodging aerosol. In the fluralaner-treated group, infestation dropped significantly from 100% at baseline to 19% over 6-10 MPT whereas mean abundance fell highly significantly from 5.5 to 0.8-0.9 triatomines per unit effort. In the placebo group, site infestation and mean abundance remained stable between 0 and 1 MPT, and strongly declined after fluralaner administration from 13.0-14.7 - triatomines at 0-1 MPT to 4.0-4.2 over 6-10 MPT. Only one of 81 noninfested sites before fluralaner treatment became infested subsequently. Fluralaner significantly reduced the site-level infestation and abundance of pyrethroid-resistant T. infestans and should be tested more widely in Phase III efficacy trials.

Validation of a documentary on Chagas disease by a population living in an endemic area / Validação de um documentário sobre a doença de Chagas por uma população de área endêmica

Abstract Educational interventions may trigger actions that contribute to prevent parasitic diseases, such as Chagas disease (CD). This study aimed at investigating the impact of an instructional video named "Documentary on Chagas Disease" on knowledge about CD and its vectors displayed by a population that lives in an endemic area in Brazil, so as to validate it as an educational tool. The video was shown to 226 subjects, divided into two groups. Group 1 was composed of users of Basic Health Units (BHU) in Pelotas and Pinheiro Machado, cities located in Rio Grande do Sul (RS) state, Brazil, where CD is endemic. Group 2 consisted of students who attend three public schools located in the rural area in Pinheiro Machado, RS. Two questionnaires with questions about their knowledge about triatomines and CD were applied, before and after the documentary was shown. After the video was shown, there was significant increase in individuals' knowledge (in both groups) about "kissing bugs", their notification, the disease and its prevention. Besides, watchers considered that the quality of the material was satisfactory. Since the "Documentary on CD" can be easily accessed on the internet and was effective in teaching the population that lives in endemic areas, its use should be encouraged in places and meetings connected to health that aim at fighting against triatominae and at exposing an updated view of CD.

Resumo Intervenções educacionais podem desencadear ações que contribuam para a prevenção de doenças parasitárias, como a doença de Chagas (DC). Este estudo teve como objetivo investigar o impacto de um vídeo instrucional denominado "Documentário Doença de Chagas" no conhecimento sobre DC e seus vetores exibidos a uma população que vive em área endêmica no Brasil, para validá-lo como uma ferramenta educacional. O vídeo foi exibido para 226 indivíduos, divididos em dois grupos. O grupo 1 foi composto por usuários das Unidades Básicas de Saúde (UBS) de Pelotas e Pinheiro Machado, cidades do estado do Rio Grande do Sul (RS), Brasil, onde a DC é endêmica. O grupo 2 foi formado por estudantes que frequentam três escolas públicas localizadas na zona rural de Pinheiro Machado, RS. Dois questionários com perguntas sobre conhecimentos sobre triatomíneos e DC foram aplicados, antes e depois da exibição do documentário. Após a exibição do vídeo, houve um aumento significativo no conhecimento dos indivíduos (em ambos os grupos) sobre "triatomíneos", sua notificação, a doença e sua prevenção. Além disso, os observadores consideraram que a qualidade do material era satisfatória. Como o "Documentário DC" pode ser facilmente acessado na Internet e ser eficaz no ensino à população que vive em áreas endêmicas, seu uso deve ser incentivado em locais e reuniões relacionadas à saúde, que visam combater os triatomíneos e exibir uma informação atualizada sobre a DC.

Do the new triatomine species pose new challenges or strategies for monitoring Chagas disease? An overview from 1979-2021

Chagas disease persists as one of the most important, and yet most neglected, diseases in the world, and several changes in its epidemiological aspects have been recorded since its discovery. Currently, some of the most relevant changes are related to: (i) the reduction in the incidence of the endemic due to the control of the most important vectors, Triatoma infestans and Rhodnius prolixus, in many countries; (ii) the migration of human populations spreading cases of the disease throughout the world, from endemic to non-endemic areas, transforming Chagas disease into a global threat; and (iii) new acute cases and deaths caused by oral transmission, especially in the north of Brazil. Despite the reduction in the number of cases, new challenges need to be responded to, including monitoring and control activities aiming to prevent house infestation by the secondary vectors from occurring. In 1979, Lent & Wygodzinsky(1) published the most complete review of the subfamily Triatominae, encompassing 111 recognised species in the taxon. Forty-two years later, 46 new species and one subspecies have been described or revalidated. Here we summarise the new species and contextualise them regarding their ecology, epidemiologic importance, and the obstacles they pose to the control of Chagas disease around the world.

Urban infestation by Triatoma infestans (Hemiptera: Reduviidae), an overlooked phenomena for Chagas disease in Argentina

Vector-borne transmission of Chagas disease in urban areas of Argentina has been an overlooked phenomena. We conducted the first comprehensive cross-sectional study of domestic infestation with Triatoma infestans and vector infection with Trypanosoma cruzi in a metropolitan area of San Juan, Argentina. Our results document the occurrence of T. infestans infected with T. cruzi in human sleeping quarters. In this urban setting, we also show that infestation was associated with construction materials, the presence of chickens, cats and a large number of dogs that can provide blood meals for the vector. Our findings reveal new challenges for vectorial control agencies.

Residual foci of Triatoma infestans infestation: Surveillance and control in Rio Grande do Sul, Brazil, 2001-2018

Abstract INTRODUCTION: This retrospective study conducted from 2001 to 2018 investigated the residual foci of Triatoma infestans infestation in Rio Grande do Sul, Brazil. METHODS: The data were obtained via entomological surveillance and the distribution of vector occurrence. The coverage of active research was mapped. RESULTS: The largest coverage rate for active research was observed in the northwest region of the total of 515,081 domiciles researched. Most T. infestans specimens were captured in the peridomicile. CONCLUSIONS: Infestation has decreased significantly since 2008, and T. infestans has not been captured since 2015.

Encuesta entomológica y caracterización de las viviendas con el vector de la enfermedad de Chagas, en aldea Chuchuapa, Santa Rosa, Guatemala / Entomological survey and characterization of houses with the vector of Chagas disease, in Chuchuapa village, Santa Rosa, Guatemala

En Guatemala en el 2015, el Ministerio de Salud Pública y Asistencia Social (MSPAS) reportó nuevos casos de la enfermedad de Chagas en la región suroriental del país, siendo Santa Rosa uno de los departamentos endémicos en donde Triatoma dimidiata es el principal transmisor. Se estimó la infestación de T. dimidiata en la aldea Chuchuapa, municipio de Santa María Ixhuatán, de abril a junio de 2019, se calcularon los índices en-tomológicos y se caracterizaron intra y peridomiciliar 149 viviendas (79.67% de las viviendas habitadas). Los datos se obtuvieron mediante un cuestionario mixto, en entrevista cara a cara y evaluación de las viviendas, por un equipo profesional experimentado, mediante el método y protocolo estándar hombre-hora. Se capturaron 20 triatominos en 10 viviendas, con un índice de infestación de 6.71% (10/149), un índice de densidad de 13.42% (20/149), 19 triatominos intradomiciliares y uno peridomiciliar, con un índice de infección natural por Tr y pano-soma cruzi intradomiciliar de 26.3% (5/19), índice de infección natural por T. cr u z i peridomiciliar de 100.0% (1/1) e índice de infección natural por T. c r u z i en los triatominos capturados de 30.0 % (6/20). Las viviendas infestadas presentaron techo de lámina, pared de bajareque con grietas y sin repello, piso de tierra y afiches en la pared, acumulación de leña u otros materiales tanto intra como peridomiciliar, convivencia con animales domésticos y tenencia de animales de corral. Los resultados representan un alto riesgo para la transmisión de la enfermedad de Chagas entre los habitantes de la aldea.

In Guatemala in 2015, the Ministry of Public Health and Social Assistance reported new cases of Chagas disease in the southeastern region of the country, with Santa Rosa being one of the endemic departments where Tr ia-toma dimidiata is the main transmitter. The infestation of T. dimidiata was estimated in the Chuchuapa village, municipality of Santa María Ixhuatán, from April to June 2019, the entomological indices were calculated and 149 dwellings were characterized intradomiciliary and peridomiciliary (79.67% of the inhabited dwellings). The data were obtained through a mixed questionnaire, in a face-to-face interview and evaluation of the dwellings, by an experienced professional team, using the standard man-hour method and protocol. 20 triatomines were captured in 10 homes, with an infestation index of 6.71% (10/149), a density index of 13.42% (20/149), 19 intradomiciliary triatomines and one peridomiciliary, with a natural infection index by intradomiciliary Trypanosomacruzi of 26.3% (5/19), natural infection index by peridomiciliary T. c r u z i of 100.0% (1/1) and natural infection index by T. c r u z i in captured triatomines of 30.0% (6/20). The infested dwellings have a sheet roof, awattle and daub wall with cracks and no wall plaster, dirt and posters on the wall, accumulation of firewood and other materials in both intradomiciliary and peridomiciliary, living with domestic animals and keeping poultry animals. The results represent a high risk for the transmission of Chagas disease among the villager.

Phenotypic and genetic variation of Triatoma costalimai (Hemiptera: Reduviidae)

Abstract INTRODUCTION: We aimed to study intraspecific variation in Triatoma costalimai, a potential vector of Chagas disease present in Brazil and Bolivia. METHODS: We analyzed phenotypic (connexivum color patterns, wing morphometrics) and genetic variation (16S mtDNA) of three Brazilian T. costalimai populations. We compared 16S sequences with those of putative Bolivian T. costalimai and its sister species, T. jatai. RESULTS: Brazilian populations had different connexivum color patterns and forewing shapes. A 16S mtDNA haplotype network showed a clear separation of Brazilian T. costalimai from both T. jatai and Bolivian T. costalimai. CONCLUSIONS: We report considerable variability in T. costalimai populations.

Proteolytic activity of Triatoma infestans saliva associated with PAR-2 activation and vasodilation

Triatoma infestans (Hemiptera: Reduviidae) is a hematophagous insect and the main vector of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae). In the present study, the authors investigated whether a serine protease activity from the saliva of T. infestans has a role in vasomotor modulation, and in the insect-blood feeding by cleaving and activating protease-activated receptors (PARs). Methods T. infestans saliva was chromatographed as previously reported for purification of triapsin, a serine protease. The cleavage activity of triapsin on PAR peptides was investigated based on FRET technology. Mass spectrometry was used to analyze the sites of PAR-2 peptide cleaved by triapsin. NO measurements were performed using the DAN assay (2,3-diaminonapthalene). The vasorelaxant activity of triapsin was measured in vessels with or without functional endothelium pre-contracted with phenylephrine (3 µM). Intravital microscopy was used to assess the effect of triapsin on mouse skin microcirculation. Results Triapsin was able to induce hydrolysis of PAR peptides and showed a higher preference for cleavage of the PAR-2 peptide. Analysis by mass spectrometry confirmed a single cleavage site, which corresponds to the activation site of the PAR-2 receptor. Triapsin induced dose-dependent NO release in cultured human umbilical vein endothelial cells (HUVECs), reaching a maximum effect at 17.58 nM. Triapsin purified by gel-filtration chromatography (10-16 to 10-9 M) was applied cumulatively to mouse mesenteric artery rings and showed a potent endothelium-dependent vasodilator effect (EC30 = 10-12 M). Nitric oxide seems to be partially responsible for this vasodilator effect because L-NAME (L-NG-nitroarginine methyl ester 300 µM), a nitric oxide synthetase inhibitor, did not abrogate the vasodilation activated by triapsin. Anti-PAR-2 antibody completely inhibited vasodilation observed in the presence of triapsin activity. Triapsin activity also induced an increase in the mouse ear venular diameter. Conclusion Data from this study suggest a plausible association between triapsin activity mediated PAR-2 activation and vasodilation caused by T. infestans saliva.(AU)

Systematic review on the biology, ecology, genetic diversity and parasite transmission potential of Panstrongylus geniculatus (Latreille 1811) in Latin America

Panstrongylus geniculatus (Latreille, 1811) is the triatomine with the largest geographic distribution in Latin America. It has been reported in 18 countries from southern Mexico to northern Argentina, including the Caribbean islands. Although most reports indicate that P. geniculatus has wild habitats, this species has intrusive habits regarding human dwellings mainly located in intermediate deforested areas. It is attracted by artificial light from urban and rural buildings, raising the risk of transmission of Trypanosoma cruzi. Despite the wide body of published information on P. geniculatus, many knowledge gaps exist about its biology and epidemiological potential. For this reason, we analysed the literature for P. geniculatus in Scopus, PubMed, Scielo, Google Scholar and the BibTriv3.0 databases to update existing knowledge and provide better information on its geographic distribution, life cycle, genetic diversity, evidence of intrusion and domiciliation, vector-related circulating discrete taxonomic units, possible role in oral T. cruzi transmission, and the effect of climate change on its biology and epidemiology.

Estado de la resistencia a insecticidas en Triatoma infestans de Argentina

Los insectos triatominos son los vectores de la enfermedad de Chagas. El control químico de estos insectos es la principal herramienta utilizada para reducir la incidencia de la enfermedad. Los piretroides son los principales insecticidas utilizados para el control de los triatominos en todos los países endémicos. La evolución de resistencia a insecticidas convierte en inefciente una exitosa estrategia de control químico. En Argentina se han detectado diferentes focos de resistencia en Triatoma infestans, el vector más importante en el Cono Sur de Sudamérica, asociados a defciencias en el control. Los estudios realizados sobre esta especie muestran que la resistencia es un problema complejo, ya que evolucionó en varias zonas de la distribución geográfca de la especie, se identifcaron diferentes mecanismos de resistencia, está asociada a modifcaciones en diversos procesos biológicos, está vinculada a variaciones ambientales y hay escasez de alternativas de control. En este manuscrito presentamos una revisión del conocimiento sobre la resistencia a piretroides en T. infestans en Argentina.

A successful community-base pilot programme to control insect vectors of Chagas disease in rural Guatemala

The adoption of novel integrated vector management (IVM) strategies requires proof-of-concept demonstrations. To implement a community-based intervention, for the control of vectors of Chagas disease in Guatemala, we engaged all relevant stakeholder groups. Based on this and previous experiences of the authors on engaged research and community-based interventions, several key factors can help facilitate effective integration of stakeholders in support of area-wide integrated vector management (AW - IVM) programmes. First and foremost, the diversity of stakeholders needs to be engaged early-on in the participatory action research and implementation processes, to provide ownership and contribute ideas on how to design and implement an intervention. Another important component, situational analysis regarding current pest control policies, practices and relevant stakeholders, is generated through interviews with key informants, at both national and local levels (governmental and non-governmental organizations); it can facilitate the joint identification of strengths, weaknesses, opportunities and threats regarding current pest control strategies and proposing solutions through an AW-IVM approach. In addition, successful AW - IVM can result from identifying locally relevant strategies to implement the proof-of-concept demonstrative project. Further, it is critical to maintain constant communication with the local and national leaders, involving them throughout the implementation and evaluation processes. Flexibility should also be built into the project to allow for community-driven changes in the strategy, through a cyclical joint reflective process. Periodic feedback of project development needs to be scheduled with key stakeholders to maintain rapport. Finally, the results of the evaluation should be shared and discussed with stakeholders to ensure long-term sustainability of the programme, intervention, or project. Here we present the citizen engagement procedures used to integrate community members, health officials, and non-governmental organization staff for Chagas disease control in a region of Guatemala. We demonstrate how these methods can be applied to support AW-IVM programmes, so that communities and authorities are actively involved in the development and implementation of a jointly agreed intervention. In 2012, we developed the IVM intervention in an area of Guatemala with persistentTriatoma dimidiata (Latreille) infestation that is associated with the presence of infected rodents (rats and mice), that act as reservoirs of the Trypanosoma cruzi Chagas parasites inside the households. Nine control communities received only the Ministry of Health insecticide application against the vector and nine intervention communities participated in the AW-IVM intervention. The intervention included a programme for rodent control by the community members, together with education about the risk factors for vector infestation, and insecticide application by the Ministry of Health. Entomological evaluations in 2014 and 2015 showed that vector infestation remained significantly lower in both intervention and control communities. In 2015, we found that there was a higher acceptance of vector surveillance activities in the intervention communities compared to control communities, suggesting that participatory activities increase programme sustainability. Finally, we found that there was a significant increase over time in the number of households with infected vectors in the control group, whereas there was no significant increase in the communities that participated in the programme. Thus, an AW-IVM programme including simultaneous rodent and vector control could reduce the risk of Chagas infection in communities with persistent vector infestation.

Insecticidal efficacy of fluralaner (Bravecto®) against Triatoma brasiliensis, a major vector of Trypanosoma cruzi in Brazil

Background: Triatomines are responsible for the vector transmission of the protozoan parasite Trypanosoma cruzi, which causes Chagas disease. Triatoma brasiliensis is the main vector of the parasite in Brazil, and dogs are an important reservoir of the parasite. The aim of this study was to evaluate the insecticidal efect of furalaner (Bravecto®) on T. brasiliensis after a blood meal in treated dogs. Methods: Healthy mongrel dogs (n=8) were recruited from the Zoonoses Control Center (ZCC) in the city of Natal, Rio Grande do Norte, Brazil, and randomized into two groups, a furalaner (Bravecto®)-treated group (n=4) and a control group (n=4). Colony-reared third-, fourth- and ffth-instar nymphs of T. brasiliensis nymphs (n=10) were allowed to feed on dogs from both groups for 30­40 min, once monthly, for up to 12 months. Bug mortality was observed up to 5 days after each blood meal. Results: Mortality in triatomines which had a blood meal on furalaner (Bravecto®)-treated dogs was 100% for up to 7 months after treatment, with mortality decreasing to 66.4% after 8 months, 57% after 9 months, 35% after 10 months, 10% after 11 months and 0% after 12 months. The mortality of triatomines that fed on non-treated control dogs was always ≤ 2.5%. Conclusions: Our results suggest that furalaner (Bravecto®) treatment of dogs induces long-term mortality of T. brasiliensis after the blood meal. This is a potential approach to be used to control vector transmission of T. cruzi, the etiological agent of Chagas disease, especially in endemic areas.

Biogeographical factors determining Triatoma recurva distribution in Chihuahua, México, 2014 / Factores biogeográficos determinantes de la distribución de Triatoma recurva en Chihuahua, México, 2014

Introduction: Triatoma recurva is a Trypanosoma cruzi vector whose distribution and biological development are determined by factors that may influence the transmission of trypanosomiasis to humans. Objective: To identify the potential spatial distribution of Triatoma recurve, as well as social factors determining its presence. Materials and methods: We used the MaxEnt software to construct ecological niche models while bioclimatic variables (WorldClim) were derived from the monthly values of temperature and precipitation to generate biologically significant variables. The resulting cartography was interpreted as suitable areas for T. recurva presence. Results: Our results showed that the precipitation during the driest month (Bio 14), the maximum temperature during the warmest month (Bio 5), and the altitude (Alt) and mean temperature during the driest quarter (Bio 9) determined T. recurva distribution area at a higher percentage evidencing its strong relationship with domestic and surrounding structures. Conclusions. This methodology can be used in other geographical contexts to locate potential sampling sites where these triatomines occur.

Introducción. Triatoma recurva es un vector de Trypanosoma cruzi cuya existencia y desarrollo biológico están determinados por factores que pueden influir en la transmisión de la tripanosomiasis a los seres humanos. Objetivo. Determinar una posible distribución espacial de Triatoma recurva y algunos factores sociales que determinan su presencia. Materiales y métodos. El modelado de nicho ecológico se hizo con el programa MaxEnt empleando las variables bioclimáticas (WorldClim) derivadas de los valores mensuales de temperatura y precipitación para generar variables biológicamente significativas. La cartografía resultante evidenció áreas adecuadas para la presencia de T. recurva. Resultados. Los resultados indicaron que la precipitación del mes más seco (Bio 14), la temperatura máxima del mes más cálido (Bio 5), y la altitud (Alt) y la temperatura media del trimestre más seco (Bio 9), determinaron en mayor porcentaje el área de distribución de T. recurva, observándose que es una especie con una acentuada relación con las estructuras domésticas y circundantes. Conclusión. Esta metodología puede emplearse en otros contextos geográficos para localizar posibles sitios de muestreo de estos triatominos.

Determination of insecticides' lethal concentrations and metabolic enzyme levels in Triatoma dimidiata / Determinación de concentraciones letales y niveles de enzimas metabólicas de insecticidas en Triatoma dimidiata

Abstract: Objective: The feasibility of the use of WHO impregnated paper and biochemical assays to determine lethal concentrations (LC50 and LC99) and insecticide metabolic enzyme levels of Triatoma dimidiata. Materials and methods: LC50 and LC99 were calculated with WHO papers impregnated at different concentrations of malathion, propoxur and deltamethrin; the percentage of insensitive acetylcholinesterase (iAChE); and the levels of esterases, glutathione S-transferases, and monooxygenases in laboratory nymphs of the first stage (5 to 7 days), were undertaken using the WHO biochemical assays. Results: Respectively the LC50 and LC99 µg/cm2 obtained for malathion were 43.83 and 114.38, propoxur 4.71 and 19.29, and deltamethrin 5.80 and 40.46. A 30% of the population had an iAChE, and only a few individuals had high P450 and β-eterase levels. Conclusion: Impregnated papers and biochemical tests developed by WHO for other insects, proved to be feasible methods in monitoring insecticide resistance and metabolic enzymes involved in T. dimidiata.

Resumen: Objetivo: La factibilidad de usar los papeles impregnados y ensayos bioquímicos según la OMS para determinar concentraciones letales (CL50 y CL99) y niveles enzimáticos en la resistencia a insecticidas en Triatoma dimidiata. Material y métodos: Se calcularon la CL50 y CL99 con papeles impregnados según la OMS a diferentes concentraciones de malatión, propoxur y deltametrina; el porcentaje de acetilcolinesterasa insensible (iAChE); y los niveles de esterasas, glutatión S-transferasas, y monooxigenasas en ninfas de laboratorio del estadio I (5-7 días) se determinaron usando los ensayos bioquímicos según la OMS. Resultados: Se obtuvieron las CL50 y CL99 µg / cm2 respectivamente para malatión 43.83 y 114.38, propoxur 4.71 y 19.29, y deltametrina 5.80 y 40.46. Un 30% de las chinches tuvo iAChE, y sólo pocos individuos tuvieron niveles superiores de P450 y β-eterasas. Conclusión: Los papeles impregnados y ensayos bioquímicos que describe la OMS para otros insectos demostraron ser métodos factibles para monitorear la resistencia a insecticidas y las enzimas metabólicas involucradas en T. dimidiata.

Cytotaxonomy of Dipetalogaster maxima Uhler, 1894 (Hemiptera, Reduviidae, Triatominae) / Citotaxonomia de Dipetalogaster maxima Uhler, 1894 (Hemiptera, Reduviidae, Triatominae)

Abstract The Triatomini tribe consists of ten genera and is regarded as one of the most important tribes from epidemiological point of view. The genus Dipetalogaster Usinger, 1939 is composed only by the species Dipetalogaster maxima Uhler, 1894. This triatomine is exclusive of the Mexico and is a potential vector for Chagas disease. Besides the epidemiological importance, the insects of the Triatominae subfamily are important biological models for cytogenetic studies. Therefore, in order to contribute to the knowledge on the reproductive biology and assist in citotaxonomy of D. maxima, this study aimed to describe spermatogenesis, as well as confirm the karyotype and heterochromatic patterns of this Mexican triatomine species. The seminiferous tubules were torn, fixed to a cover slip and underwent the cytogenetic technique of Lacto-acetic orcein and C-banding. Through the cytogenetics analysis of testicular material D. maxima it was possible to confirm the karyotype (2n = 22), describe the stages of spermatogenesis and characterize the heterochromatic pattern (restricted to sex chromosome Y) of the species. D. maxima showed the same arrangement of heterochromatin described for Triatoma lecticularia (Stål, 1859) (a species that occur in United States of American and Mexico and is phylogenetically related with D. maxima), highlighting the importance of this analysis as an optimization tool to explore phylogenetic correlations.

Resumo A tribo Triatomini consiste em dez gêneros e é considerada uma das tribos mais importantes do ponto de vista epidemiológico. O gênero Dipetalogaster Usinger, 1939 é composto apenas pela espécie Dipetalogaster maxima Uhler, 1894. Este triatomíneo é exclusivo do México e é um vetor potencial da doença de Chagas. Além da importância epidemiológica, os insetos da subfamília Triatominae são importantes modelos biológicos para estudos citogenéticos. Portanto, a fim de contribuir para o conhecimento da biologia reprodutiva e complementar o conceito específico de D. maxima, este trabalho objetivou descrever a espermatogênese, bem como confirmar o padrão cariotípico e heterocromático desta espécie mexicana, com foco citotaxonômico. Os túbulos seminíferos foram dilacerados, fixados em uma lamínula e submetidos à técnica citogenética de Orceína lacto-acética e Bandamento-C. Por meio da análise citogenética do material testicular de D. maxima foi possível confirmar o cariótipo (2n = 22), descrever os estágios da espermatogênese e caracterizar o padrão heterocromático (restrito ao cromossomo Y sexual) da espécie. D. maxima apresentou o mesmo arranjo de heterocromatina descrito para Triatoma lecticularia (Stål, 1859) (espécie que ocorre no México e nos Estados Unidos da América, filogeneticamente relacionada com D. maxima), destacando a importância desta técnica como ferramenta para explorar correlações filogenéticas.