Papers by Patricia Lobbia
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Fil: Rodriguez, Claudia Susana. Universidad Nacional de Cordoba. Facultad de Cs.exactas Fisicas y... more Fil: Rodriguez, Claudia Susana. Universidad Nacional de Cordoba. Facultad de Cs.exactas Fisicas y Naturales. Departamento de Biologia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina
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Background Chagas disease is a neglected tropical disease and Trypanosoma cruzi (its etiological ... more Background 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 Arge...
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En este trabajo se presentan los resultados del análisis tafonómico efectuado en el depósito Yegu... more En este trabajo se presentan los resultados del análisis tafonómico efectuado en el depósito Yegua
Quemada 3, Parque Nacional Monte León, con una ubicación cronológica correspondiente al
Holoceno medio (5360 ± 20 años AP). Los resultados muestran que el material arqueomalacológico
se encuentra en un proceso de degradación avanzado, resultado de períodos de exposición,
indicados por la pérdida de color, pero también de enterramiento, indicado por la pérdida de
las capas externas y la dureza de las valvas. Los restos de vertebrados muestran asimismo la
importancia que los procesos bioestratinómicos y diagenéticos tuvieron en la historia depositacional
del conjunto. Las superficies óseas están afectadas de manera homogénea, lo que indica
exposición a condiciones subaéreas. El conjunto artefactual lítico presenta evidencias de haber
pasado por períodos de exposición subaérea, evidenciado por la abrasión eólica y períodos de
enterramiento, mostrado por el desarrollo de un revestimiento de carbonato. El conjunto de evidencias
considerado y las variables tafonómicas analizadas permiten concluir que el depósito
YQ3 brinda información adecuada para discutir la ocupación humana al sur del río Santa Cruz en
un bloque temporal, el Holoceno medio, período para el cual se cuenta con limitada información.
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Background: The Sordida subcomplex (Triatominae) comprises four species, Triatoma garciabesi, T. ... more Background: The Sordida subcomplex (Triatominae) comprises four species, Triatoma garciabesi, T. guasayana, T. patagonica and T. sordida, which differ in epidemiological importance and adaptations to human environments. Some morphological similarities among species make taxonomic identification, population differentiation and
species delimitation controversial. Triatoma garciabesi and T. sordida are the most similar species, having been considered
alternatively two and a single species until T. garciabesi was re-validated, mostly based on the morphology of male genitalia. More recently, T. sordida from Argentina has been proposed as a new cryptic species distinguishable from T. sordida from Brazil, Bolivia and Paraguay by cytogenetics. We studied linear and geometric morphometry of the head, wings and pronotum in populations of these species aiming to find phenotypic markers for their discrimination, especially between T.
sordida and T. garciabesi, and if any set of variables that validates T. sordida from Argentina as a new species.
Results: Head width and pronotum length were the linear variables that best differentiated species. Geometric morphometry revealed significant Mahalanobis distances in wing shape between all pairwise comparisons. Triatoma patagonica exhibited the best discrimination and T. garciabesi overlapped the distribution of the other species in the
morphometric space of the first two DFA axes. Head shape showed differentiation between all pairs of species except for T. garciabesi and T. sordida. Pronotum shape did not differentiate T. garciabesi from T. guasayana. The comparison
between T. garciabesi and T. sordida from Argentina and T. sordida from Brazil and Bolivia revealed low differentiation based on head and pronotum linear measurements. Pronotum and wing shape were different between T. garciabesi and T. sordida from Brazil and Bolivia and T. sordida from Argentina. Head shape did not differentiate T. garciabesi from T. sordida from Argentina.
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The domiciliary presence of Triatoma infestans (Klug) (Hemiptera: Redu-viidae) after control inte... more The domiciliary presence of Triatoma infestans (Klug) (Hemiptera: Redu-viidae) after control interventions was reported in recent years. Toxicological studies showed high levels of resistance to pyrethroids suggesting resistance as one of the main causes of deficient control. The aim of the present study was to develop a protocol to test resistance to deltamethrin in T. infestans collected from the field by discriminate concentration. To evaluate field insects, the effect of age (early vs. later) and nutritional state (starved vs. fed) on the deltamethrin susceptibility of each developmental stage was studied. Topical and insecticide impregnated paper bioassays were used. Using the impregnated paper, the susceptibility to deltamethrin was not affected by the age of the stadium and the nutritional states, and varied with the post-exposure time and with the different developmental stages. A discriminant concentration of deltamethrin (0.36% w/v) impregnated in filter paper was established for all developmental stages. Finally, the methodology and the discriminant concentration were evaluated in the laboratory showing high sensitivity in the discrimination of resistance. The present study developed a methodology of exposure to insecticide impregnated papers and proposes a protocol to test T. infestans in field populations with the aim to detect early evolution of resistance to deltamethrin.
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Resumen La fragmentación es uno de los procesos tafonómicos más importantes en las aso-ciaciones ... more Resumen La fragmentación es uno de los procesos tafonómicos más importantes en las aso-ciaciones 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. Morphometric analysis of Mytilus edulis: a tool for analysing shell middens and Patagonian Coastal archaeology Abstract Fragmentation is one of the most important taphonomic processes in archaeomala-cological 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 edu-lis 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, Palabras clave Mytilus edulis Fragmentación Morfometría Arqueomalacología Costa patagónica Keywords Mytilus edulis Fragmentation Morphometry Archaeomalacology Coastal Patagonia
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Archaeofauna, 2019
This paper presents the results of the taphonomic analysis carried out in the Yegua Quemada 3 arc... more This paper presents the results of the taphonomic analysis carried out in the Yegua Quemada 3 archaeological deposit, Monte León National Park, dated back to the mid Holocene. The results show that the archaeomalacological materials are in a process of advanced degradation, being the result of exposure, indicated by the loss of color, but also of burial, indicated by the loss of the outer layers and hardness of shells. Vertebrate remains also show the importance that biostratinomic and diagenetic processes had in the site depositional history. These materials have a slightly weathered/weathered profile, with the bony surfaces affected in a homogeneous way, indicating exposure to subaerial conditions. The artefactual assemblage shows evidence of having gone through periods of subaerial exposure, evidenced by wind abrasion, and burial periods too, shown by the development of the carbonate layer. The set of evidences considered and the taphonomic variables analyzed here allow to conclude that YQ3 deposit provides adequate data to discuss the human occupation south of the Santa Cruz River in the middle Holocene.
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Transmission of Trypanosma cruzi (Kinetoplastida: Trypanosomatidae) occurs when feces/urine of in... more 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.
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The nymphs and adults of Triatoma infestans spend much of their time aggregated among themselves ... more The nymphs and adults of Triatoma infestans spend much of their time aggregated among themselves within narrow and dark shelters. The search for a suitable shelter depends in part on the recognition of chemical signals coming from the feces and the cuticle of the other individuals who use the refuge. The aim of this study was
determine the possible interaction between the chemical signals associated to the feces and to the cuticle of T. infestans. The results showed that the insects remained significantly more time on the feces that had contact with legs and the feces plus footprints than feces or footprints alone, demonstrating the interaction between evaluated
signals. These results demonstrates also that feces extracted a chemical stimulus from the legs. Understanding the interaction feces-legs as an interaction feces-cuticle of legs, the results suggest that the feces could extract some cuticular compound with activity on the behavior of the insects. This is the first report of the interaction
between the two aggregation signals recognized in T. infestans and of the increase in the behavioral response of insects exposed to feces that had contact with a cuticular structure.
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Primer registro de colonias domésticas de la variante cromática oscura de Triatoma infestans (Hem... more Primer registro de colonias domésticas de la variante cromática oscura de Triatoma infestans (Hemiptera: Reduviidae) RESUMEN. 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. PALABRAS CLAVE. Morfo oscuro. Triatominae. Variantes geográficas. ABSTRACT. 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.
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Pyrethroid resistance has been detected in Triatoma infestans (Klug)
(Hemiptera: Reduviidae) spec... more 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.
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Triatoma infestans (Klug, 1834) is the main vector of the Chagas´ disease in Argentina. The prese... more 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.
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The dispersal of insects is determinant in the colonization of new areas and the propagation of i... more 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.
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Claudia Rodríguez, Patricia Lobbia, Julieta Nattero,
Silvia Catalá and Liliana Crocco
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Thesis Chapters by Patricia Lobbia
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Conference Presentations by Patricia Lobbia
Una de las particularidades que presentan los sitios concheros es la diversidad de especies de mo... more Una de las particularidades que presentan los sitios concheros es la diversidad de especies de moluscos que los conforman y el modo en que varían las especies predominantes de cada sitio a lo largo de la costa. Cada especie presenta características estructurales (químicas) y ecológicas (incluso ornamentales) que le son particulares y responden de manera diferencial a diferentes procesos ambientales (bióticos y abióticos). Dada la importancia que tiene el estudio de las variables tafonómicas para la interpretación de los procesos involucrados en la formación de los sitios concheros, es que toma relevancia conocer la respuesta de cada especie particular a los diferentes procesos tafonomicos, analizando para ello distintas variables.
El objetivo de este trabajo es comparar las características tafonómicas que presentan los bivalvos recuperados en el sitio conchero P 27, depósito compuesto principalmente por restos de Aulacomya atra y Mytilus edulis. En éste depósito, ubicado en la desembocadura del rio Santa Cruz, Argentina, se recuperó una muestra sistemática de 883 valvas de A. atra y 572 de M. edulis, en las que se analizaron 8 variables tafonómicas (fragmentación, color, bioerosión, corrosión, abrasión, presencia de periostraco, marca de golpe y conservación de capa la prismática). Los resultados obtenidos reflejan que las especies difieren significativamente (p<0,0001) en 7 variables, no mostrando diferencias tafonómicas en el color. M. edulis presenta menor abrasión y mejor conservación de la capa prismática que A. atra, pero se ve afectada en mayor medida por la bioerosión, la perdida de periostraco y la corrosión. Al analizar las marcas de golpe y la fragmentación A. atra presenta una mayor porcentaje de valvas con marcas de golpe y mayor grado de fragmentación que M. edulis. Esto estaría indicando que las condiciones de vida previas a la depositación afectarían las posibilidades de conservación de las mismas ya que las marca de golpe generadas mientras el organismo estaba vivo podrían implicar una mayor debilidad de las valvas al momento de depositación. Por otro lado, la predominancia de ambas especies en el sitio constituye un indicador de que fueron recolectadas de bancos de moluscos mixtos cercanos a la costa. A modo de conclusión señalamos, por un lado, que las características intrínsecas de estas dos especies responden de manera diferencial a iguales procesos tafonómicos bajo condiciones semejantes. Por otro lado, señalamos también que la distribución geográfica y las características de hábitat (mesolitoral o profundidad) como así también la interacción con otras especies (bancos de moluscos mixtos o no) influyen en su conservación final. Estas observaciones son importantes al momento de analizar el proceso de formación de cada sitio en particular y al realizar comparaciones entre diferentes sitios con diferente composición de especies como así también, al abordar los análisis regionales.
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Papers by Patricia Lobbia
Quemada 3, Parque Nacional Monte León, con una ubicación cronológica correspondiente al
Holoceno medio (5360 ± 20 años AP). Los resultados muestran que el material arqueomalacológico
se encuentra en un proceso de degradación avanzado, resultado de períodos de exposición,
indicados por la pérdida de color, pero también de enterramiento, indicado por la pérdida de
las capas externas y la dureza de las valvas. Los restos de vertebrados muestran asimismo la
importancia que los procesos bioestratinómicos y diagenéticos tuvieron en la historia depositacional
del conjunto. Las superficies óseas están afectadas de manera homogénea, lo que indica
exposición a condiciones subaéreas. El conjunto artefactual lítico presenta evidencias de haber
pasado por períodos de exposición subaérea, evidenciado por la abrasión eólica y períodos de
enterramiento, mostrado por el desarrollo de un revestimiento de carbonato. El conjunto de evidencias
considerado y las variables tafonómicas analizadas permiten concluir que el depósito
YQ3 brinda información adecuada para discutir la ocupación humana al sur del río Santa Cruz en
un bloque temporal, el Holoceno medio, período para el cual se cuenta con limitada información.
species delimitation controversial. Triatoma garciabesi and T. sordida are the most similar species, having been considered
alternatively two and a single species until T. garciabesi was re-validated, mostly based on the morphology of male genitalia. More recently, T. sordida from Argentina has been proposed as a new cryptic species distinguishable from T. sordida from Brazil, Bolivia and Paraguay by cytogenetics. We studied linear and geometric morphometry of the head, wings and pronotum in populations of these species aiming to find phenotypic markers for their discrimination, especially between T.
sordida and T. garciabesi, and if any set of variables that validates T. sordida from Argentina as a new species.
Results: Head width and pronotum length were the linear variables that best differentiated species. Geometric morphometry revealed significant Mahalanobis distances in wing shape between all pairwise comparisons. Triatoma patagonica exhibited the best discrimination and T. garciabesi overlapped the distribution of the other species in the
morphometric space of the first two DFA axes. Head shape showed differentiation between all pairs of species except for T. garciabesi and T. sordida. Pronotum shape did not differentiate T. garciabesi from T. guasayana. The comparison
between T. garciabesi and T. sordida from Argentina and T. sordida from Brazil and Bolivia revealed low differentiation based on head and pronotum linear measurements. Pronotum and wing shape were different between T. garciabesi and T. sordida from Brazil and Bolivia and T. sordida from Argentina. Head shape did not differentiate T. garciabesi from T. sordida from Argentina.
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.
determine the possible interaction between the chemical signals associated to the feces and to the cuticle of T. infestans. The results showed that the insects remained significantly more time on the feces that had contact with legs and the feces plus footprints than feces or footprints alone, demonstrating the interaction between evaluated
signals. These results demonstrates also that feces extracted a chemical stimulus from the legs. Understanding the interaction feces-legs as an interaction feces-cuticle of legs, the results suggest that the feces could extract some cuticular compound with activity on the behavior of the insects. This is the first report of the interaction
between the two aggregation signals recognized in T. infestans and of the increase in the behavioral response of insects exposed to feces that had contact with a cuticular structure.
(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.
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.
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.
Thesis Chapters by Patricia Lobbia
Conference Presentations by Patricia Lobbia
El objetivo de este trabajo es comparar las características tafonómicas que presentan los bivalvos recuperados en el sitio conchero P 27, depósito compuesto principalmente por restos de Aulacomya atra y Mytilus edulis. En éste depósito, ubicado en la desembocadura del rio Santa Cruz, Argentina, se recuperó una muestra sistemática de 883 valvas de A. atra y 572 de M. edulis, en las que se analizaron 8 variables tafonómicas (fragmentación, color, bioerosión, corrosión, abrasión, presencia de periostraco, marca de golpe y conservación de capa la prismática). Los resultados obtenidos reflejan que las especies difieren significativamente (p<0,0001) en 7 variables, no mostrando diferencias tafonómicas en el color. M. edulis presenta menor abrasión y mejor conservación de la capa prismática que A. atra, pero se ve afectada en mayor medida por la bioerosión, la perdida de periostraco y la corrosión. Al analizar las marcas de golpe y la fragmentación A. atra presenta una mayor porcentaje de valvas con marcas de golpe y mayor grado de fragmentación que M. edulis. Esto estaría indicando que las condiciones de vida previas a la depositación afectarían las posibilidades de conservación de las mismas ya que las marca de golpe generadas mientras el organismo estaba vivo podrían implicar una mayor debilidad de las valvas al momento de depositación. Por otro lado, la predominancia de ambas especies en el sitio constituye un indicador de que fueron recolectadas de bancos de moluscos mixtos cercanos a la costa. A modo de conclusión señalamos, por un lado, que las características intrínsecas de estas dos especies responden de manera diferencial a iguales procesos tafonómicos bajo condiciones semejantes. Por otro lado, señalamos también que la distribución geográfica y las características de hábitat (mesolitoral o profundidad) como así también la interacción con otras especies (bancos de moluscos mixtos o no) influyen en su conservación final. Estas observaciones son importantes al momento de analizar el proceso de formación de cada sitio en particular y al realizar comparaciones entre diferentes sitios con diferente composición de especies como así también, al abordar los análisis regionales.
Quemada 3, Parque Nacional Monte León, con una ubicación cronológica correspondiente al
Holoceno medio (5360 ± 20 años AP). Los resultados muestran que el material arqueomalacológico
se encuentra en un proceso de degradación avanzado, resultado de períodos de exposición,
indicados por la pérdida de color, pero también de enterramiento, indicado por la pérdida de
las capas externas y la dureza de las valvas. Los restos de vertebrados muestran asimismo la
importancia que los procesos bioestratinómicos y diagenéticos tuvieron en la historia depositacional
del conjunto. Las superficies óseas están afectadas de manera homogénea, lo que indica
exposición a condiciones subaéreas. El conjunto artefactual lítico presenta evidencias de haber
pasado por períodos de exposición subaérea, evidenciado por la abrasión eólica y períodos de
enterramiento, mostrado por el desarrollo de un revestimiento de carbonato. El conjunto de evidencias
considerado y las variables tafonómicas analizadas permiten concluir que el depósito
YQ3 brinda información adecuada para discutir la ocupación humana al sur del río Santa Cruz en
un bloque temporal, el Holoceno medio, período para el cual se cuenta con limitada información.
species delimitation controversial. Triatoma garciabesi and T. sordida are the most similar species, having been considered
alternatively two and a single species until T. garciabesi was re-validated, mostly based on the morphology of male genitalia. More recently, T. sordida from Argentina has been proposed as a new cryptic species distinguishable from T. sordida from Brazil, Bolivia and Paraguay by cytogenetics. We studied linear and geometric morphometry of the head, wings and pronotum in populations of these species aiming to find phenotypic markers for their discrimination, especially between T.
sordida and T. garciabesi, and if any set of variables that validates T. sordida from Argentina as a new species.
Results: Head width and pronotum length were the linear variables that best differentiated species. Geometric morphometry revealed significant Mahalanobis distances in wing shape between all pairwise comparisons. Triatoma patagonica exhibited the best discrimination and T. garciabesi overlapped the distribution of the other species in the
morphometric space of the first two DFA axes. Head shape showed differentiation between all pairs of species except for T. garciabesi and T. sordida. Pronotum shape did not differentiate T. garciabesi from T. guasayana. The comparison
between T. garciabesi and T. sordida from Argentina and T. sordida from Brazil and Bolivia revealed low differentiation based on head and pronotum linear measurements. Pronotum and wing shape were different between T. garciabesi and T. sordida from Brazil and Bolivia and T. sordida from Argentina. Head shape did not differentiate T. garciabesi from T. sordida from Argentina.
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.
determine the possible interaction between the chemical signals associated to the feces and to the cuticle of T. infestans. The results showed that the insects remained significantly more time on the feces that had contact with legs and the feces plus footprints than feces or footprints alone, demonstrating the interaction between evaluated
signals. These results demonstrates also that feces extracted a chemical stimulus from the legs. Understanding the interaction feces-legs as an interaction feces-cuticle of legs, the results suggest that the feces could extract some cuticular compound with activity on the behavior of the insects. This is the first report of the interaction
between the two aggregation signals recognized in T. infestans and of the increase in the behavioral response of insects exposed to feces that had contact with a cuticular structure.
(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.
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.
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.
El objetivo de este trabajo es comparar las características tafonómicas que presentan los bivalvos recuperados en el sitio conchero P 27, depósito compuesto principalmente por restos de Aulacomya atra y Mytilus edulis. En éste depósito, ubicado en la desembocadura del rio Santa Cruz, Argentina, se recuperó una muestra sistemática de 883 valvas de A. atra y 572 de M. edulis, en las que se analizaron 8 variables tafonómicas (fragmentación, color, bioerosión, corrosión, abrasión, presencia de periostraco, marca de golpe y conservación de capa la prismática). Los resultados obtenidos reflejan que las especies difieren significativamente (p<0,0001) en 7 variables, no mostrando diferencias tafonómicas en el color. M. edulis presenta menor abrasión y mejor conservación de la capa prismática que A. atra, pero se ve afectada en mayor medida por la bioerosión, la perdida de periostraco y la corrosión. Al analizar las marcas de golpe y la fragmentación A. atra presenta una mayor porcentaje de valvas con marcas de golpe y mayor grado de fragmentación que M. edulis. Esto estaría indicando que las condiciones de vida previas a la depositación afectarían las posibilidades de conservación de las mismas ya que las marca de golpe generadas mientras el organismo estaba vivo podrían implicar una mayor debilidad de las valvas al momento de depositación. Por otro lado, la predominancia de ambas especies en el sitio constituye un indicador de que fueron recolectadas de bancos de moluscos mixtos cercanos a la costa. A modo de conclusión señalamos, por un lado, que las características intrínsecas de estas dos especies responden de manera diferencial a iguales procesos tafonómicos bajo condiciones semejantes. Por otro lado, señalamos también que la distribución geográfica y las características de hábitat (mesolitoral o profundidad) como así también la interacción con otras especies (bancos de moluscos mixtos o no) influyen en su conservación final. Estas observaciones son importantes al momento de analizar el proceso de formación de cada sitio en particular y al realizar comparaciones entre diferentes sitios con diferente composición de especies como así también, al abordar los análisis regionales.