Evaluación de la sensibilidad a insecticidas en poblaciones de Aedes aegypti (Diptera: Culicidae) del departamento de Caldas, Colombia, en 2007 y 2011 / Insecticide susceptibility evaluation in Aedes aegypti populations of Caldas, Colombia, in 2007 and 2011

Introducción. El uso continuo de insecticidas para el control de la transmisión del dengue puede generar una reducción en los niveles de sensibilidad de las poblaciones de los mosquitos vectores. La vigilancia oportuna es necesaria para detectar cualquier problema potencial de resistencia. Objetivo. Determinar el estado de la sensibilidad a insecticidas de uso en salud pública en poblaciones de Aedes aegypti del departamento de Caldas, Colombia, en el 2007 y el 2011. Materiales y métodos. Se realizaron pruebas de sensibilidad a los organofosforados temefós, malatión, fenitrotión y metil-pirimifós y al piretroide deltametrina, siguiendo las metodologías estandarizadas de la Organización Mundial de la Salud y de los Centers for Disease Control and Prevention de los Estados Unidos. Resultados. En el 2007 se encontró resistencia al temefós en dos barrios del municipio de La Dorada, con grados de resistencia de 11,5 y 13,3. Por ello, la Dirección Territorial de Salud de Caldas suspendió el uso de este larvicida en dichos barrios. Cuatro años después, en el 2011, se observó una reducción en los grados de resistencia al temefós, así como resistencia al metil-pirimifós. Todas las poblaciones evaluadas fueron sensibles a los insecticidas deltametrina, malatión y fenitrotión en los dos períodos. Conclusión. La cuantificación de los grados de resistencia en dos períodos permitió evidenciar la reducción de la resistencia al temefós después de suspender su uso. Se recomienda mantener la vigilancia de los niveles de sensibilidad de los insecticidas usados en los programas de control de dengue.

Introduction: Continuous use of insecticides for the control of dengue transmission may lead to decreased susceptibility levels in mosquito vector populations. Timely monitoring is necessary to ensure detection of any potential resistance problems. Objective: To determine the susceptibility status of Aedes aegypti to insecticides used in public health in Caldas, Colombia, during 2007 and 2011. Materials and methods: Susceptibility tests to the organophosphates temephos, malathion, fenitrothion and pirimiphos methyl, as well as to the pyrethroid deltamethrin, were carried out using standard World Health Organization and Centers for Disease Control and Prevention protocols. Results: In 2007, resistance to temephos was detected in Ae. aegypti populations from La Dorada with resistance ratios of 11.5 and 13.3, prompting the Caldas Health Department to suspend the use of this larvicide. A reduction in resistance ratios to temephos was observed in 2011, as well as an apparent resistance to pirimiphos methyl. All Ae. aegypti populations tested were susceptible to deltamethrin, malathion and fenitrothion in both years. Conclusion: Evaluating the resistance ratios during two distinct periods allowed a decrease in resistance to be detected after suspension of the use of temephos. Surveillance of mosquito populations for changes in susceptibility levels to the insecticides used in dengue control programs is therefore recommended.

Anopheles species composition explains differences in Plasmodium transmission in La Guajira, northern Colombia

Malaria in La Guajira, the most northern state of Colombia, shows two different epidemiological patterns. Malaria is endemic in the municipality of Dibulla whereas in Riohacha it is characterised by sporadic outbreaks. This study aimed to establish whether differences in transmission patterns could be attributed to different vector species. The most abundant adult female species were Anopheles aquasalis, exclusive to Riohacha, and Anopheles darlingi, restricted to Dibulla. Anopheles mosquitoes were identified using morphology and the molecular markers internal transcribed spacer 2 and cytochrome c oxidase I. All specimens (n = 1,393) were tested by ELISA to determine natural infection rates with Plasmodium falciparum and Plasmodium vivax. An. darlingi was positive for P. vivax 210, with an infection rate of 0.355% and an entomological inoculation rate of 15.87 infective bites/person/year. Anopheles albimanus larvae were the most common species in Riohacha, found in temporary swamps; in contrast, in Dibulla An. darlingi were detected mainly in permanent streams. Distinctive species composition and larval habitats in each municipality may explain the differences in Plasmodium transmission and suggest different local strategies should be used for vector control.

Morphology of the larvae, male genitalia and DNA sequences of Anopheles (Kerteszia) pholidotus (Diptera: Culicidae) from Colombia

Since 1984, Anopheles (Kerteszia) lepidotus has been considered a mosquito species that is involved in the transmission of malaria in Colombia, after having been incriminated as such with epidemiological evidence from a malaria outbreak in Cunday-Villarrica, Tolima. Subsequent morphological analyses of females captured in the same place and at the time of the outbreak showed that the species responsible for the transmission was not An. lepidotus, but rather Anopheles pholidotus. However, the associated morphological stages and DNA sequences of An. pholidotus from the foci of Cunday-Villarrica had not been analysed. Using samples that were caught recently from the outbreak region, the purpose of this study was to provide updated and additional information by analysing the morphology of female mosquitoes, the genitalia of male mosquitoes and fourth instar larvae of An. pholidotus, which was confirmed with DNA sequences of cytochrome oxidase I and rDNA internal transcribed spacer. A total of 1,596 adult females were collected in addition to 37 larval collections in bromeliads. Furthermore, 141 adult females, which were captured from the same area in the years 1981-1982, were analysed morphologically. Ninety-five DNA sequences were analysed for this study. Morphological and molecular analyses showed that the species present in this region corresponds to An. pholidotus. Given the absence of An. lepidotus, even in recent years, we consider that the species of mosquitoes that was previously incriminated as the malaria vector during the outbreak was indeed An. pholidotus, thus ending the controversy.

Comportamiento de picadura de Anopheles darlingi Root,1926 (Diptera: Culicidae) y su asociación con la transmisiónde malaria en Villavicencio (Colombia) / Biting behavior of Anopheles darlingi Root, 1926 (Diptera: Culicidae) and its association with malaria transmission in Villavicencio (Meta, Colombia)

Introducción. Anopheles darlingi es el principal vector de la malaria, o paludismo, en el neotrópico. Esta especie es reconocida por presentar un comportamiento antropofílico y variabilidad en sus hábitos de picadura a lo largo de su rango de distribución. Objetivo. Caracterizar el comportamiento de picadura de An. darlingi y establecer su relación con la transmisión de la malaria en Villavicencio. Materiales y métodos. Entre 2008 y 2009 se llevaron a cabo un estudio de tipo transversal y uno longitudinal, en cinco localidades de Villavicencio con transmisión de malaria. Estos incluyeron recolección de ejemplares inmaduros y de adultos en las viviendas. Se utilizó la prueba ELISA para la detección de infección con Plasmodium spp. Resultados. Se recolectaron 2.772 mosquitos. Anopheles darlingi fue la especie predominante en las capturas con atrayente humano. Los criaderos identificados para esta especie fueron pantanos, caños, lagunas y estanques piscícolas. Anopheles darlingi estuvo presente durante todo el año, con densidades mensuales promedio entre 2,2 y 55,5 mosquitos por persona por noche. Presentó actividad hematofágica durante toda la noche en el intradomicilio y en el peridomicilio. De las 18:00 a las 22:00, se registraron entre el 47 % y el 81 % de los mosquitos capturados en 12 horas de observación. Se encontró una tasa de infección con Plasmodium falciparum de 0,05 % y se estimó una tasa entomológica de inoculación de 2,9 picaduras infecciosas por persona al año. Conclusión. Anopheles darlingi se encontró infectado con P. falciparum, estuvo presente durante todo el año y exhibió características en su comportamiento de picadura que favorecen el contacto entre humano y vector, lo cual es un riesgo permanente para la transmisión de la malaria en Villavicencio.

Introduction: Anopheles darlingi is the main malaria vector in the neotropics. This species is recognized by its anthropophilic behavior and its high variability in biting activity throughout its distribution range. Objective: To characterize the biting behavior of An. darlingi and to establish its association with malaria transmission in Villavicencio. Materials and methods: Between 2008 and 2009, a cross sectional and a longitudinal entomological study were carried out in 5 localities with malaria transmission in Villavicencio. Mosquito collections included breeding sites search and human landing catches in houses. Collected mosquitoes were analyzed for Plasmodium using the ELISA standard protocol. Results: A total of 2,772 mosquitoes were collected in the study. Anopheles darlingi was the most abundant anopheline species. The most common breeding sites for this species were marshes, streams, lakes and fish ponds. Anopheles darlingi was found at all times during the year with monthly average human biting rates between 2.2 y 55.5 mosquitos/person/night. This species was collected throughout the night, indoors and outdoors, and 47 to 81% of An. darling captured during twelve hours of observation (18:00 to 06:00) were collected between18:00 and 22:00. Anopheles darlingi was found positive for P. falciparum with a 0.05% rate and the entomological inoculation rate was estimated at 2.9 infective bites/person per year. Conclusion: Anopheles darlingi was infected with P. falciparum, it was found all year long and it exhibited characteristics in biting behavior that favor human-vector contact, being a permanent risk for malaria transmission in Villavicencio.

Especies de Anopheles presentes en el departamento del Putumayo y su infección natural con Plasmodium / Anopheles species present in the department of Putumayo and their natural infectivity with Plasmodium

Introducción. El departamento del Putumayo es una región endémica para malaria, o paludismo, causada principalmente por Plasmodium vivax . Los vectores en esta región incluyen Anopheles darlingi , el cual se ha encontrado solamente en el municipio de Puerto Leguízamo, y recientemente se incriminaron como vectores en Puerto Asís a las especies An. rangeli y An. oswaldoi . Objetivo. El propósito del trabajo fue determinar el papel de An. benarrochi B en la transmisión de malaria en este departamento, ya que se reporta como la especie más abundante que pica a los humanos. Materiales y métodos. Se recolectaron larvas y adultos de Anopheles spp. entre el 2006 y el 2008 en los municipios Puerto Leguízamo y Puerto Asís, y se obtuvieron secuencias del gen ITS-2 y del gen mitocondrial COI para confirmar las determinaciones taxonómicas por morfología. Se practicó la prueba ELISA para establecer la infección por P. vivax y P. falciparum. Resultados. Se identificaron 6.238 individuos correspondientes a 11 especies: An. albitarsis s.l. (1,83 %), An. benarrochi B (72,35 %), An. braziliensis (0,05 %), An. costai (0,06 %), An. darlingi (19,37 %), An. mattogrossensis (0,08 %), An. neomaculipalpus (0,13 %), An. oswaldoi s.l. (0,64 %), An. punctimacula (0,03 %), An. rangeli (5,12 %) y An. triannulatus s.l. (0,34 %). Se evaluaron 5.038 adultos por ELISA y 5 se encontraron positivos para P. vivax 210 y VK 247, todos pertenecientes a la especie An. benarrochi B. Conclusión. Los resultados sugieren que An. benarrochi B juega un papel en la transmisión de P. vivax en el departamento de Putumayo, dada su alta atracción por los humanos y su infección natural con Plasmodium spp.

Introduction: Putumayo is considered an endemic region for malaria transmission, mainly due to Plasmodium vivax. The vectors in this region are Anopheles darlingi , which has been found only in the municipality of Puerto Leguízamo, and An. rangeli and An. oswaldoi s.l. , which were recently incriminated as vectors in Puerto Asís. Objective: The purpose of this study was to determine the role of An. benarrochi B in malaria transmission in Putumayo, given that it is the most abundant species biting humans. Materials and methods: Collections of immature and adult stages of Anopheles spp. were made between 2006 and 2008 in the municipalities of Puerto Leguízamo and Puerto Asís in Putumayo, and sequences of internal transcribed spacer 2 ( ITS-2 ) of ribosomal DNA and the mitochondrial gene COI were obtained to confirm the morphological determinations. ELISA was carried out for P. vivax and P. falciparum infectivity. Results: A total of 6,238 specimens were identified, distributed in 11 species: An. albitarsis s.l. (1.83%), An. benarrochi B (72.35%), An. braziliensis (0.05%), An. costai (0.06%), An. darlingi (19.37%), An. mattogrossensis (0.08%), An. neomaculipalpus (0.13%), An. oswaldoi s.l. (0.64%), An. punctimacula (0.03%), An. rangeli (5.12%), and An. triannulatus s.l. (0.34%). A total of 5,038 adults were assessed by ELISA and 5 were found positive for P. vivax 210 and VK 247, all belonging to An. benarrochi B. Conclusion: The results suggest that An. benarrochi B plays a role in the transmission of P. vivax in Putumayo due to its high human contact and natural infection with Plasmodium sp.

Malaria vector species in Colombia: a review

Here we present a comprehensive review of the literature on the vectorial importance of the major Anopheles malaria vectors in Colombia. We provide basic information on the geographical distribution, altitudinal range, immature habitats, adult behaviour, feeding preferences and anthropophily, endophily and infectivity rates. We additionally review information on the life cycle, longevity and population fluctuation of Colombian Anopheles species. Emphasis was placed on the primary vectors that have been epidemiologically incriminated in malaria transmission: Anopheles darlingi, Anopheles albimanus and Anopheles nuneztovari. The role of a selection of local, regional or secondary vectors (e.g., Anopheles pseudopunctipennis and Anopheles neivai) is also discussed. We highlight the importance of combining biological, morphological and molecular data for the correct taxonomical determination of a given species, particularly for members of the species complexes. We likewise emphasise the importance of studying the bionomics of primary and secondary vectors along with an examination of the local conditions affecting the transmission of malaria. The presence and spread of the major vectors and the emergence of secondary species capable of transmitting human Plasmodia are of great interest. When selecting control measures, the anopheline diversity in the region must be considered. Variation in macroclimate conditions over a species' geographical range must be well understood and targeted to plan effective control measures based on the population dynamics of the local Anopheles species.

Molecular comparison of topotypic specimens confirms Anopheles (Nyssorhynchus) dunhami Causey (Diptera: Culicidae) in the Colombian Amazon

The presence of Anopheles (Nyssorhynchus) dunhami Causey in Colombia (Department of Amazonas) is confirmed for the first time through direct comparison of mtDNA cytochrome c oxidase I (COI) barcodes and nuclear rDNA second internal transcribed spacer (ITS2) sequences with topotypic specimens of An. dunhami from Tefé, Brazil. An. dunhami was identified through retrospective correlation of DNA sequences following misidentification as Anopheles nuneztovari s.l. using available morphological keys for Colombian mosquitoes. That An. dunhami occurs in Colombia and also possibly throughout the Amazon Basin, is of importance to vector control programs, as this non-vector species is morphologically similar to known malaria vectors including An. nuneztovari, Anopheles oswaldoi and Anopheles trinkae. Species identification of An. dunhami and differentiation from these closely related species are highly robust using either DNA ITS2 sequences or COI DNA barcode. DNA methods are advocated for future differentiation of these often sympatric taxa in South America.

Mixed-function oxidases and esterases associated with cross-resistance between DDT and lambda-cyhalothrin in Anopheles darlingi Root 1926 populations from Colombia

In order to establish the insecticide susceptibility status for Anopheles darlingi in Colombia, and as part of the National Network on Insecticide Resistance Surveillance, five populations of insects from three Colombian states were evaluated. Standardised WHO and CDC bottle bioassays, in addition to microplate biochemical assays, were conducted. Populations with mortality rates below 80 percent in the bioassays were considered resistant. All field populations were susceptible to deltamethrin, permethrin, malathion and fenitrothion. Resistance to lambda-cyhalothrin and DDT was detected in the Amé-Beté population using both bioassay methods with mortality rates of 65-75 percent. Enzyme levels related to insecticide resistance, including mixed function oxidases (MFO), non-specific esterases (NSE), glutathione S-transferases and modified acetylcholinesterase were evaluated in all populations and compared with a susceptible natural strain. Only mosquitoes from Amé-Beté presented significantly increased levels of both MFO and NSE, consistent with the low mortalities found in this population. The continued use of lambda-cyhalothrin for An. darlingi control in this locality has resulted in a natural resistance to this insecticide. In addition, DDT resistance is still present in this population, although this insecticide has not been used in Colombia since 1992. Increased metabolism through MFO and NSE may be involved in cross-resistance between lambda-cyhalothrin and DDT, although kdr-type nerve insensitivity cannot be discarded as a possible hypothesis. Additional research, including development of a kdr specific assay for An. darlingi should be conducted in future studies. Our data demonstrates the urgent need to develop local insecticide resistance management and surveillance programs throughout Colombia.

Retos de la entomología médica para la vigilancia en salud pública en Colombia: reflexión para el caso de malaria / Challenges of the medical entomology for the surveillance in public health in Colombia: reflections on the state of malaria

Se presenta una reflexión sobre la pertinencia del fortalecimiento de la vigilancia entomológica en los programas de control de paludismo en un escenario como Colombia, haciendo un reconocimiento de los vacíos de información sobre el conocimiento de las especies vectores y resaltando las acciones básicas que requiere el país en este campo. Bajo la premisa que los programas de control de vectores deben estar basados en resultados de los estudios entomológicos locales y dar respuestas prácticas a preguntas orientadas al control de la enfermedad, se mencionan algunas dificultades por resolver con relación a las especies de Anopheles en Colombia, particularmente en lo que tiene que ver con la taxonomía e incriminación como vectores y los retos que se podrían asumir en este aspecto.

Incrimination of Anopheles (Nyssorhynchus) rangeli and An. (Nys.) oswaldoi as natural vectors of Plasmodium vivax in Southern Colombia

Malaria transmission in the Southern Colombian state of Putumayo continues despite the absence of traditional vector species, except for the presence of Anopheles darlingi near the southeastern border with the state of Amazonas. In order to facilitate malaria vector incrimination in Putumayo, 2445 morphologically identified Anopheles females were tested for natural infection of Plasmodium vivax by ELISA. Specimens tested included An. apicimacula (n = 2), An. benarrochi B (n = 1617), An. darlingi (n = 29), An. mattogrossensis (n = 7), An. neomaculipalpus (n = 7), An. oswaldoi (n = 362), An. peryassui (n = 1), An. punctimacula (n = 1), An. rangeli (n = 413), and An. triannulatus (n = 6). Despite being overwhelmingly the most anthropophilic species in the region and comprising 66.1 percent of the mosquitoes tested, An. benarrochi B was not shown to be a vector. Thirty-five An. rangeli and one An. oswaldoi were naturally infected with P. vivax VK210. Sequence data were generated for the nuclear second internal transcriber space region of 31 of these 36 vivax positive mosquitoes (86.1 percent) to confirm their morphological identification. An. oswaldoi is known to be a species complex in Latin America, but its internal taxonomy remains unresolved. Herein we show that the An. oswaldoi found in the state of Putumayo is genetically similar to specimens from the state of Amapá in Brazil and from the Ocama region in the state of Amazonas in Venezuela, and that this form harbors natural infections of P. vivax. That An. rangeli and this member of the An. oswaldoi complex are incriminated as malaria vectors in Putumayo, is a novel finding of significance for malaria control in Southern Colombia, and possibly in other areas of Latin America.

Laboratory estimation of the effects of increasing temperatures on the duration of gonotrophic cycle of Anopheles albimanus (Diptera: Culicidae)

The increase of malaria transmission in the Pacific Coast of Colombia during the occurrence of El Niño warm event has been found not to be linked to increases in the density of the vector Anopheles albimanus, but to other temperature-sensitive variables such as longevity, duration of the gonotrophic cycle or the sporogonic period of Plasmodium. The present study estimated the effects of temperature on duration of the gonotrophic cycle and on maturation of the ovaries of An. albimanus. Blood fed adult mosquitoes were exposed to temperatures of 24, 27, and 30ºC, held individually in oviposition cages and assessed at 12 h intervals. At 24, 27, and 30ºC the mean development time of the oocytes was 91.2 h (95 percent C.I.: 86.5-96), 66.2 h (61.5-70.8), and 73.1 h (64-82.3), respectively. The mean duration of the gonotrophic cycle for these three temperatures was 88.4 h (81.88-94.9), 75 h (71.4-78.7), and 69.1 h (64.6-73.6) respectively. These findings indicate that both parameters in An. albimanus are reduced when temperatures rose from 24 to 30ºC, in a nonlinear manner. According to these results the increase in malaria transmission during El Niño in Colombia could be associated with a shortening of the gonotrophic cycle in malaria vectors, which could enhance the frequency of man-vector contact, affecting the incidence of the disease.

Molecular differentiation of Anopheles (Nyssorhynchus) benarrochi and An. (N.) oswaldoi from Southern Colombia

Anopheles (Nyssorhynchus) benarrochi, An. (N.) oswaldoi, and An. (N.) rangeli are the most common anthropophilic mosquitoes in the southern Colombian state of Putumayo. Adult females are most commonly collected in epidemiological studies, and this stage poses significant problems for correct identification, due to overlapping inter-specific morphological characters. Although An. rangeli is easy to identify, the morphological variant of An. benarrochi found in the region and An. oswaldoi are not always easy to separate. Herein we provide a rapid molecular method to distinguish these two species in Southern Colombia. Sequence data for the second internal transcribed spacer (ITS2) region of rDNA was generated for link-reared progeny of An. benarrochi and An. oswaldoi, that had been identified using all life stages. ITS2 sequences were 540 bp in length in An. benarrochi (n = 9) and 531 bp in An. oswaldoi (n = 7). Sequences showed no intra-specific variation and ungapped inter-specific sequence divergence was 6.4 percent. Species diagnostic banding patterns were recovered following digestion of the ITS2 amplicons with the enzyme Hae III as follows: An. benarrochi (365, 137, and 38 bp) and An. oswaldoi (493 and 38 bp). This polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay provides rapid, accurate, and inexpensive species diagnosis of adult females. This will benefit future epidemiological studies and, as PCR amplification can be achieved using a single mosquito leg, the remaining specimen can be either retained as a morphological voucher or further used in vector incrimination studies. That An. benarrochi comprises a complex of at least two species across Latin America is discussed.

Utilidad de la morfología de los huevos como un método indirecto para identificar Anopheles benarrochi Gabaldón, Cova García & López, Anopheles oswaldoi (Peryassu) y Anopheles rangeli Gabaldón, Cova García & López, (Diptera: Culicidae) en Putumayo, Colombia / Egg morphology as an indirect method to identify Anopheles benarrochi, Anopheles oswaldoi and Anopheles rangeli (Diptera: Culicidae)

La identificación correcta de las hembras es esencial para el éxito de cualquier estudio de epidemiología, resistencia a insecticidas o de control de vectores. En el departamento del Putumayo, en el sur de Colombia, la transmisión de malaria continúa siendo un problema, a pesar de la ausencia de los vectores principales de Latinoamérica (Anopheles darlingi Root, Anopheles nuneztovari Gabaldón, Anopheles albimanus Wideman, Anopheles trinkae Faran) en esta región. Se recolectaron. con cebo humano, hembras de Anopheles y se encontró una variante morfológica de Anopheles benarrochi, que en su estadio adulto fácilmente se confunde con Anopheles oswaldoi. La identificación de hembras de Anopheles, particularmente del subgénero Nyssorhynchus, es en general notoriamente difícil debido a la superposición de caracteres morfológicos en el estadio adulto; por tanto, las colecciones deben estar ligadas a la cría de material asociado para identificar correctamente las especies. Esto requiere tiempo y es difícil de obtener en muchas ocasiones. Se presenta un método indirecto de identificación de las especies A. benarrochi, A. oswaldoi y Anopheles rangeli del sur de Colombia usando la morfología de los huevos de hembras silvestres. Los huevos de A. rangeli y A. benarrochi se diferencian por la corona anterior, la cual es apical en A. rangeli y con paredes altas, mientras que en A. benarrochi es ventral y con paredes más cortas. Esta corona está ausente en A. oswaldoi. Estas diferencias fueron obvias incluso bajo un microscopio de luz, lo que hace posible una identificación correcta de estas especies en condiciones de campo. Se muestra cómo la observación de la morfología de los huevos puede permitir la determinación taxonómica correcta, aunque indirecta, de estas tres especies de Nyssorhynchus encontradas en el sur de Colombia, el cual puede ser útil también en otras regiones de Latinoamérica, en donde se encuentre la variante morfológica de A. benarrochi en simpatría con A. oswaldoi.Palabras clave: Nyssorhynchus, huevos, Anopheles, Colombia, microscopia electrónica.Egg morphology as an indirect method to identify Anopheles benarrochi, Anopheles oswaldoi and Anopheles rangeli (Diptera: Culicidae).

Morphometric discrimination of females of five species of Anopheles of the subgenus Nyssorhynchus from Southern and Northwest Colombia

The most important vectors of human Plasmodium in the neotropics belong to the subgenus Nyssorhynchus. These species are generally sympatric in terms of their geographical distributions. Some are difficult to identify based solely on examination of adult females using the available morphological keys, in these cases examination of immature stages and male genitalia is required to make correct determinations. However, in epidemiological studies it is necessary to identify the species of adult females which are found near humans, i.e. in studies of malaria transmission or evaluation of control measures. The purpose of the present study was to evaluate the discrimination of adult females of different species of Nyssorhynchus isolated mainly from Southern Colombia (department of Putumayo), using morphometric analysis. Adult females were obtained after rearing larvae collected in natural breeding places and from the progeny of females collected on humans. The morphological characteristics of the immature stages allowed the identification of four species of the subgroup Oswaldoi from Southern Colombia: Anopheles rangeli Gabaldon, Cova Garcia & Lopez, An. oswaldoi (Peryassu), An. benarrochi Gabaldon, Cova Garcia & Lopez and An. triannulatus (Neiva & Pinto). The species An. nuneztovari (Gabaldon) from the Northwest of Colombia was included for comparison. Morphometric analysis allowed differentiation of the females of all species to a confidence level approaching 90 percent using principal components analysis of 10 wing and leg variables, followed by canonical variate analysis of the first four principal components. We conclude that morphometrics may represent a useful taxonomic tool for this group and that its use should be further studied

Variante morfológica de adultos hembras de Anopheles / Morphological variation in Anopheles benarrochi (Diptera: Culicidae) adult females specimens from Putumayo, Colombia

Con el propósito de ampliar el conocimiento sobre las especies de Anopheles presentes en el Putumayo, sur de Colombia, y para esclarecer la identidad de los ejemplares clasificados como Anopheles (Nyssorhynchus) evansae en esta región, se recolectaron mosquitos hembra en cebo humano, se alimentaron en pequeños mamíferos y se mantuvieron vivos para la cría de isofamilias. Se realizaron observaciones de las características morfológicas de los huevos, larvas, pupas y adultos de ambos sexos, incluidas las genitalias masculinas. Se obtuvieron 247 posturas de madres identificadas preliminarmente como A. (N) evansee. A 27 de estas familias se le estudió la morfología de los estadios asociados. Todos los especímenes fueron subsecuentemente identificados como Anopheles (N:) benarrochi por la morfología de los huevos, larvas, pupas y genitalias masculinas, lo cual coincidió con las descripciones publicadas para esta especie. Sin embargo, los adultos hembra de Putumayo presentaron la proporción oscura en el tarsómero posterior 2, entre 0.17 y 0,33 de su longitud, inferior a lo informado para esta especie, lo cual se superpone con los rangos de Anopheles (N.) oswaldoi y A. (N.) evansae. Como resultado de la superposición en este carácter, es probable que hembras adultas de A. (N.) benarrochi hayan sido incorrectamente identificadas como A. (N.) evansae y A. (N.) oswaldoi en el sur de Colombia. La presencia de esta variante morfológica ha dificultado la identificación de A. (N.) benarrochi en Putumayo y, probablemente, en otras regiones de Colombia y países vecinos

Presencia de Aedes albopictus en Leticia, Amazonas, Colombia / Aedes albopictus presence in Leticia, Amazonas, Colombia

La especie Aedes albopictus es un eficiente vector del dengue en Asia y posiblemente, de otros arbovirus incluyendo la fiebre amarilla y la encefalitis. En la última década se ha extendido la distribución de A. albopictus a las Américas. En la ciudad de Tabatinga, Brasil, muy cerca de la frontera con Colombia, se ha informado la presencia de esta especie en 1996 y posteriormente, en octubre de 1997. En marzo de 1998, en desarrollo de un estudio sobre enfermedades tropicales realizado por el Programa de Estudio y Control de Enfermedades Tropicales, PECET, de la Universidad de Antioquia y la Secretaria de Salud del Amazonas, se capturaron 8 ejemplares adultos de A. albopictus en la ciudad de Leticia, departamento del Amazonas, siendo éste el primer hallazgo de esta especie en Colombia. La presencia en Colombia de A. albopictus vuelve más complejo el problema del dengue por la mayor adaptación de este vector a climas más fríos, la capacidad de transmisión transovariana, la buena capacidad vectorial para transmitir los cuatro serotipos del virus y la mayor dificultad para su control dado que sus criaderos están en áreas peridomésticas y rurales. La distribución de esta especie tanto en zonas selváticas como rurales y urbanas presenta un peligro potencial de urbanizar la transmisión de la fiebre amarilla. Se presenta el plan de contigencia que se debe implementar por parte de la Secretaría de Salud del Amazonas con miras a evitar la propagación de este vector a otras regiones del país

Comportamiento de Anopheles (Kerteszia) Lepidotus Zavortink, 1973, y su Incriminacion como posible Vector de Malaria en el Departamento del Tolima, Colombia (1) / Behavior of the Anopheles (Kerteszia) Lepidotus Zavortink, 1973, and its incrimination as possible vector of Malaria at the Department of Tolima, Colombia

En un foco de transmision de malaria en el Departamento del Tolima, que comprende 16 localidades de los municipios de Cunday, Villarrica, Dolores, Prado y Purificacion; y donde se encuentran unicamente casos autoctonos de Plasmodium se realizaron estudios entomologicos desde abril de 1981 hasta mayo de 1983. Se colectaron con cebo humano 2.209 mosquitos Anopheles, todos del subgenero Kerteszia, de los cuales el 99.5% (2.209) fue Anopheles Lepidotus Zavortink, 1973 y los restantes 10(0,5%) An. Boliviensis Theobald, 1905. Se concluye, con evidencia epidemiologica, que An. Lepidotus es el posible vector en este foco. Es el primer registro conocido en que esta especie se incrimina como posible vector de malaria en Colombia. Antiguas observaciones en este foco habian incrementado como responsable de la transmision de malaria a An. Boliviensis, debido a confusiones taxonomicas, aclaradas en los ultimos 10 anos. Las mas altas densidades de An. Lepidotus ocurrieron de enero a junio y el pico de densidad precedio por cerca de 2 meses al pico de casos de malaria. Se encontro que An. Lepidotus es altamente exofagica (3,7 veces mayor actividad de picadura fuera de las casas que dentro) y exofilica (92% de las hembras que picaron, salieron son reposar en las superficies dentro de las casas). Su habito de picadura es diurno, con un pico de actividad entre las 15:00 y 18:00 horas. No se encontro..