State of Insecticide Resistance in Triatoma infestans in 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 ineficiente 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 deficiencias 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 geográfica de la especie, se identificaron diferentes mecanismos de resistencia, está asociada a modificaciones 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.Os insetos triatomíneos são os vetores da doença de Chagas. O controlo químico desses insetos é a principal ferramenta utilizada para reduzir a incidência da doença. Os piretróides são os principais inseticidas usados para controlar os triatomíneos em todos os países endémicos. A evolução da resistência aos inseticidas converte em ineficiente uma estratégia de controlo químico eficiente. Na Argentina foram detetados diferentes focos de resistência em Triatoma infestans, o vetor mais importante do Cone Sul da América do Sul, associados a deficiências de controlo. Os estudos realizados nesta espécie mostram que a resistência é um problema complexo, visto que evoluiu em várias áreas da distribuição geográfica da espécie. Foram identificados diferentes mecanismos de resistência, associados a modificações em vários processos biológicos e ligados a variações ambientais, havendo uma escassez de alternativas de controlo. Neste manuscrito é apresentada uma revisão do conhecimento sobre a resistência aos piretróides em T. infestans na Argentina.Triatominae (kissing bugs) are the vectors of Chagas disease. Chemical control of these insects is the main tool for reducing the incidence of the disease. Pyrethroids are the main insecticides used for triatomine control in all endemic countries. The evolution of insecticide resistance renders a successful chemical control strategy ineffective. In Argentina, different foci of resistance have been detected in Triatoma infestans—the most important vector in the Southern Cone of South America, which are associated with control deficiencies. The studies conducted on this species show that resistance is a complex problem because it has evolved in several areas of the species’ geographical distribution. Different resistance mechanisms have been identified. Resistance is associated with changes in various biological processes and linked to environmental changes. There is a lack of control alternatives. This paper is a review of the knowledge on pyrethroid resistance in T. infestans in Argentina.Fil: Mougabure Cueto, Gastón Adolfo. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Lobbia, Patricia Alejandra. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Primer registro de colonias domésticas de la variante cromática oscura de Triatoma infestans (Hemiptera: Reduviidae)

Triatoma infestans (Klug) es el principal vector de la enfermedad de Chagas en el sur de Sudamérica. Aunque esta especie muestra una morfología y un patrón cromático similar a través de su distribución geográfica, algunas variantes melánicas han sido descriptas. La mayoría de estas variantes fueron reconocidas como parte de poblaciones silvestres, que evidenció una distribución silvestre de T. infestans mayor a la esperada. Este trabajo informa la presencia de ocho adultos y quince individuos inmaduros de T. infestans melánicos en unidades domiciliarias en el Gran Chaco argentino. Este es el primer registro de colonias domésticas de la variante cromática oscura de T. infestans.Triatoma infestans (Klug) is the main vector of Chagas disease in southern South America. Although this species shows a similar morphology and chromatic pattern throughout its geographical distribution, some melanic variations have been described. Most of these variants were recognized as part of wild populations constituting evidence of a wild distribution for T. infestans greater than the expected. This paper reports the presence of eight adults and fifteen immature individuals of melanic T. infestans in domiciliary units of Argentine Gran Chaco. This is the first report of domestic colonies of the dark chromatic morph of T. infestans.Fil: Lobbia, Patricia Alejandra. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Álvarez, Rodrigo. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; ArgentinaFil: Picollo, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Analysis of Chagas disease vectors occurrence data: the Argentinean triatomine species database

Chagas disease is a neglected tropical disease and Trypanosoma cruzi (its etiological agent) is mainly transmitted by triatomines (Hemiptera: Reduviidae). All triatomine species are considered as potential vectors; thus, their geographic distribution and habitat information should be a fundamental guide for the surveillance and control of Chagas disease. Currently, of the 137 species distributed in the Americas (Justi and Galvão 2017), 17 species are cited for Argentina: Panstrongylus geniculatus, P. guentheri, P. megistus, P. rufotuberculatus, Psammolestes coreodes, Triatoma breyeri, T. delpontei, T. eratyrusiformis, T. garciabesi, T. guasayana, T. infestans, T. limai, T. patagonica, T. platensis, T. rubrofasciata, T. rubrovaria and T. sordida. Almost 20 years have passed since the publication of the “Atlas of the Triatominae” by Carcavallo et al. (1998) and no work has been done to provide an updated complete integration and analysis of the existing information for Argentinean triatomine species. Here we provide a detailed temporal, spatial and ecological analysis of updated occurrence data for triatomines present in Argentina.Fil: Ceccarelli, Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Balsalobre, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Cano, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Canale, Delmi Margarita. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; ArgentinaFil: Lobbia, Patricia Alejandra. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Stariolo, Raúl Luis. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; ArgentinaFil: Rabinovich, Jorge Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Marti, Gerardo Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentin

Morphometric analysis of Mytilus edulis: a tool for analysing shell middens and Patagonian Coastal archaeology

La fragmentación es uno de los procesos tafonómicos más importantes en las asociaciones arqueomalacológicas. La gran cantidad de material fragmentado introduce sesgos que afectan la interpretación de los procesos de formación, conservación de los depósitos y las estrategias de subsistencia de los grupos humanos. El objetivo de este trabajo es analizar el proceso de fragmentación de Mytilus edulis, en el sitio PE 133, poniendo a prueba la morfometría como herramienta de estudio. Los resultados obtenidos demostraron que no se puede establecer una relación entre el tamaño de las valvas y el grado de fragmentación. Esto indicaría que la fragmentación depende de las características propias del molusco donde el espesor, forma y la composición química son más determinantes que el tamaño del individuo, el tipo de sedimento y la historia de formación del depósito. Finalmente, la fragmentación introduce sesgos en los análisis de longitud de los individuos, es así que, en este contexto las ecuaciones morfométricas se convierten en herramientas de gran utilidad que permiten incorporar en los análisis aquellos individuos fragmentados disminuyendo los sesgos que este proceso produce.Fragmentation is one of the most important taphonomic processes in archaeomalacological assemblages. The quantity of fragmented malacological material introduces biases that affect the interpretation of formation processes, shell midden preservation and human gathering strategies. In this paper we analyze the process of Mytilus edulis fragmentation at the PE 133 site, thereby presenting a methodology for studying archaeomalacological assemblages. The results show that no relationship could be established between shell size and the degree of fragmentation. This demonstrates that fragmentation depends on the mollusk characteristics. Therefore, shell thickness, shape and chemical composition, are more important that the size of the individual,the type of sediment, or site formation history. Finally, fragmentation introduces bias into shell length analysis, so that morphometric equations are a useful tool that permits us to to study fragmented individuals, resulting in a decrease in fragmentation bias.Fil: Lobbia, Patricia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Antropología de Córdoba. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Instituto de Antropología de Córdoba; Argentin

Active dispersal in Triatoma infestans (Klug, 1834) (Hemiptera: Reduviidae: Triatominae): Effects of nutritional status, the presence of a food source and the toxicological phenotype

In Argentina, the main vector of Chagas disease is Triatoma infestans (Klug, 1834). In recent years, the presence of T. infestans was reported in human dwelling after spraying with pyrethroids in several locations in Argentina. The presence of these insects can be attributed, among other factors, to colonization by bugs from sylvatic or peridomestic populations or to the evolution of resistance to insecticides. In both cases, the dispersal of insects is a determining factor. The aim was to determinate the interaction of dispersal with feeding, food resource and resistance to insecticides. Three nutritional states were obtained with the number of feeds (NF) offered (0, 1 or 2). The resistant females were evaluated only with NF1. The experimental arena was 10 m long and contained two shelters. Groups of 30 virgin females of each NF were released in one of the shelters and were able to move during 3 days/nights. Females without possibility of dispersal were the controls. Results showed that the individuals dispersed mainly walking regardless of the number of feeds, the presence of food resource and toxicological phenotype. This type of dispersal presented energy costs in susceptible individuals but not in resistant ones. The numbers of feeds that determined low nutritional states showed greater dispersal and activity associated with the shelter. The presence of a food source had an effect on the dispersal capacity and this depended on the number of feeds. There was a decrease in the dispersal in individuals with one feeding and an absence of response in fasted individuals and with two feeds. On the other hand, a lower dispersal tendency were found in resistant females compared to susceptible females, suggesting that resistance to deltamethrin is associated with adaptive costs.Fil: Lobbia, Patricia Alejandra. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Effect of reproductive state on active dispersal in Triatoma infestans (Klug, 1834)(Hemiptera: Reduviidae: Triatominae) susceptible and resistant to deltamethrin

Triatoma infestans (Klug, 1834)is the main vector of the Chagas´ disease in Argentina. The presence of insects in the domestic environment after application of pyrethroid insecticides was reported. The colonization and the evolution of insecticide resistance are processes that can explain these control failures. In both processes, the active dispersal of insects is a determining factor. The aim of the present study was to determine whether the reproductive state modulate the dispersal capacity of females of T. infestans susceptible and resistant to deltamethrin. For this, different variables associated with active dispersal were measured in virgin and copulated females both susceptible and resistant to deltamethrin. The experimental arena was 10 m long and contained two shelters. Groups of 12 females of each experimental group were released in one of the shelters and were able to move during 3 days/nights. The results showed that the females mainly dispersed by walking regardless of the reproductive state and the toxicological phenotype. On the other hand, the copula affected the posterior dispersal capacity in females susceptible and resistant to deltamethrin. The copulated females dispersed more times, leaved more times from the shelters and showed a higher proportion of dispersed individuals than the virgin females. Finally, the insecticide resistance reduced the dispersal capacity of females. The resistant insects showed lower number of dispersal events, a lower proportion of dispersed individuals, and lower exit and entry events from/to shelter than susceptible insects. This is the first report of the effect of copula on the capacity of active dispersion in vectors of Chagas disease susceptible and resistant to insecticides.Fil: Lobbia, Patricia Alejandra. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodriguez, C.. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Departamento de Fisiología. Cátedra de Introducción A la Biología; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Universidad Nacional de Córdoba; Argentin

Effects of the infection with Trypanosoma cruzi on the feeding and excretion/defecation patterns of Triatoma infestans

Transmission of Trypanosma cruzi (Kinetoplastida: Trypanosomatidae) occurs when feces/urine of infected triatomines come into contact with mucous membranes or damaged skin, and this occurs mainly when insects defecate while feeding on the host. Thus, the vector competence of the triatomines is associated with their feeding and excretion/defecation behavior. This work studied for the first time the effect of T. cruzi infection on feeding and excretion/defecation patterns of Triatoma infestans (Hemiptera: Reduviidae). Uninfected and infected fifth-instar nymphs were fed ad libitum and their feeding behavior and defecations were registered during and after feeding. The feeding pattern did not show differences between the experimental groups. However, the infected nymphs began to defecate earlier, defecated in greater quantity and there was a greater proportion of defecating individuals compared to uninfected nymphs. These results show that T. cruzi affected the excretion/defecation pattern of T. infestans in a way that would increase the probability of contact between infective feces and the mammalian host.Fil: Pereyra, Nicolás. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; ArgentinaFil: Lobbia, Patricia Alejandra. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentin

Effect of nutritional state and dispersal on the reproductive efficiency in Triatoma infestans (Klug, 1834) (Hemiptera: Reduviidae: Triatominae) susceptible and resistant to deltamethrin

The dispersal of insects is determinant in the colonization of new areas and the propagation of insecticide resistance. Nutritional status and reproductive characteristics determine the colonization capacity after the dispersal event. Studies about of the effects of dispersal on reproduction in triatomines are few and none in resistant insects. The aim was to determine the effects of nutritional state and dispersal on the subsequent reproductive potential in Triatoma infestans (Klug, 1834) susceptible and resistant to deltamethrin. Three nutritional states were obtained with the number of feeds (NF) offered (0, 1 or 2). The resistant females were evaluated only with NF1. The experimental arena was 10 m long and contained two shelters. Groups of 30 virgin females of each NF were released in one of the shelters and were able to move during 3 days/nights. Females without possibility of dispersal were the controls. The reproductive parameters were determined on the couples between the experimental females and males from the breeding. The results showed that most of the females dispersed by walking. The dispersal had effects on the reproduction of the deltamethrin-susceptible females and this depended on the number of feeds. Fecundity, fertility and the proportion of females that oviposited were higher in females dispersed with two feeds but was lower in females dispersed with less feeds. In addition, the effect of the dispersal on the reproduction and the life time also depended of the toxicological phenotype. The resistant insect oviposited in higher proportion and showed greater fecundity and more weeks of life when they dispersed that when they did not do it, and was opposite to that observed in susceptible ones. Finally, the resistance to insecticide had an effect on the reproduction and the life span and this effect depended on whether the insects dispersed or not.Fil: Lobbia, Patricia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; ArgentinaFil: Rodriguez, Claudia Susana. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Excretion/defecation patterns in Triatoma infestans populations that are, respectively, susceptible and resistant to deltamethrin

Pyrethroid resistance has been detected in Triatoma infestans (Klug) (Hemiptera: Reduviidae) specimens from different areas of Argentina and Bolivia. Genes conferring resistance can have a pleiotropic effect with epidemiological and evolutionary consequences. This research studied excretion/defecation patterns in deltamethrin-resistant T. infestans in order to elucidate its biological performance, adaptive consequences and role in the transmission of Chagas' disease. One deltamethrin-susceptible strain and two deltamethrin-resistant strains were used. Fifth-instar nymphs were fed ad libitum and their defecations recorded during and after the first or second feeding in the stadium. Resistant insects began to defecate later, defecated less, showed a lower proportion of defecating individuals and lower defecation indices compared with susceptible insects during the first hour after feeding. The number of bloodmeals in the stadium did not affect the main variables determining the pattern of defecation. The present study suggests that alterations in the excretion/defecation pattern in resistant insects entail an adaptive cost and, considering only this pattern, determine a lower capacity for transmission of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) compared with susceptible insects.Fil: Lobbia, Patricia Alejandra. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Calcagno, Javier Ángel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico. Departamento de Ciencias Naturales y Antropológicas; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Autogenic capacity in Triatoma infestans (Klug, 1834) (Hemiptera: Reduviidae) susceptible and resistant to deltamethrin

The insecticide resistance in Triatoma infestans (Klug, 1834) was detected in different areas of its geographical distribution. The mechanisms of resistance involved can affect different biological processes in addition to toxicological ones. Previous studies showed that reproductive efficiency was modified in resistant females compared to susceptible ones. The objective of this study was to compare the autogenic capacity and subsequent reproductive potential between deltamethrin-resistant and susceptible T. infestans. For each toxicological phenotype, pairs were formed between unfed adult females and recently fed adult male, which were separated after confirming copulation. Females were observed weekly until death, and reproductive parameters (initiation of mating, initiation of oviposition, fecundity, fertility and period between mating and initiation of oviposition) were recorded. Females from both toxicological phenotypes showed autogenic capacity. However, a lower proportion of deltamethrin-resistant unfed females laid eggs. Autogenic females showed a higher nutritional status than non-autogenic ones. No other differences in reproductive parameters were found between resistant and susceptible autogenic females. The possible mechanisms underlying the differences observed and their consequences on the spread of resistance are discussed. This is the first report describing the effect of pyrethroid resistance on T. infestans autogeny.Fil: Lobbia, Patricia Alejandra. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Remón, Carolina María. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Mougabure Cueto, Gastón Adolfo. Ministerio de Salud. Dirección de Enfermedades Transmisibles por Vectores. Centro de Referencia de Vectores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin