Browsing by Autor "Rosenka Tejerina"

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A physiological time analysis of the duration of the gonotrophic cycle of Anopheles pseudopunctipennis and its implications for malaria transmission in Bolivia
(BioMed Central, 2008) Frédéric Lardeux; Rosenka Tejerina; Vicente Quispe; Tamara Chávez
Comparison of transmission parameters between Anopheles argyritarsis and Anopheles pseudopunctipennis in two ecologically different localities of Bolivia
(BioMed Central, 2013) Frédéric Lardeux; Claudia Aliaga; Rosenka Tejerina; Libia Torrez
Development of Exon-Primed Intron-Crossing (EPIC) PCR primers for the malaria vector Anopheles pseudopunctipennis (Diptera: Culicidae)
(Elsevier BV, 2012) Frédéric Lardeux; Claudia Aliaga; Rosenka Tejerina; Raùl Ursic-Bedoya
Using the Anopheles gambiae Giles genome as a template, we designed, screened and identified 14 novel Exon-Primed Intron-Crossing (EPIC) PCR primer pairs for Anopheles pseudopunctipennis Theobald 1901, a major vector of human Plasmodium sp. in South America. These primers were designed to target the conserved regions flanking consecutive exons of different genes and enabled the amplification of 17 loci of which nine were polymorphic. Polymorphisms at these loci ranged from two to four alleles. Intron length polymorphism analysis is a useful tool, which will allow the study of the population structure of this mosquito species, which remains poorly understood.
First concrete documentation for presence of Aedes (Stegomyia) albopictus in Bolivia: Dispelling previous anecdotes
(2024) Frédéric Lardeux; Philippe Boussès; Rosenka Tejerina; Audric Berger; Christian Barnabé; Lineth García
Abstract Background The presence of Aedes albopictus in Bolivia has been a subject of controversy, lacking concrete documentation until now. Objectives This study aimed to furnish evidence of Ae. albopictus presence in Bolivia. Methods Larval breeding sites were sampled in two northern Bolivian localities, Rosario del Yata and San Agustin, both situated in the Beni department within the Vaca Diez province and Guayaramerin Municipio, approximately 10 km apart. Mosquito larvae collected underwent rearing to L4 and adult stages for morphological identification, with some specimens sequenced for confirmation. Findings Ae. albopictus was identified in multiple breeding sites in both localities, confirming its establishment in the area. This marks the first concrete documentation of the species in Bolivia. The collections (larvae and adults) have been deposited in the Medical Entomology Laboratory of the Universidad Mayor de San Simón in Cochabamba, Bolivia, and the Laboratory of Entomology of the Instituto Nacional de Laboratorios de Salud of the Ministry of Health in La Paz, Bolivia. Main conclusion Acknowledging its role as a vector for arboviruses like dengue and Chikungunya, Ae. albopictus should be incorporated into the Bolivian National Program of Vector Control for monitoring.
First concrete documentation for presence of Aedes (Stegomyia) albopictus in Bolivia: dispelling previous anecdotes
(Instituto Oswaldo Cruz, Ministério da Saúde, 2024) Frédéric Lardeux; Philippe Boussès; Rosenka Tejerina; Audric Berger; Christian Barnabé; Lineth García
Given its role as a vector for arboviruses such as dengue and Chikungunya, Ae. albopictus should be incorporated into the Bolivian National Programme of Vector Control for monitoring.
Laboratory colonization of Anopheles pseudopunctipennis (Diptera: Culicidae) without forced mating
(Elsevier BV, 2007) Frédéric Lardeux; Vicente Quispe; Rosenka Tejerina; Roberto Rodríguez; Libia Torrez; Bernard Bouchité; Tamara Chávez
Anopheles pseudopunctipennis is one of the main malaria vectors in the Andean regions of South America. Few experimental data exist on this species because it is not very available in laboratories due to its eurygamic status that makes colony maintenance difficult. Indeed, individuals do not mate in the confined space of insectary cages. To avoid this problem, forced artificial mating can be used. However, this technique is time consuming, requires a well-trained technician, and is inadequate for easy mass production, which is sometimes necessary for certain experimental works. This study presents a technique based on exposure of adult mosquitoes to a blue stroboscopic light for 20 min during several nights, which encourages them to copulate naturally under laboratory conditions. After some generations, a self-free-mating strain was obtained. The technique is simple, inexpensive and is probably effective whatever the An. pseudopunctipennis strain considered.
Modeling the development of Triatoma infestans through temperature: Estimating generation time in Bolivia
(2023) Frédéric Lardeux; Stéphanie Depickère; Rosenka Tejerina
Abstract Background In Bolivia, controlling Triatoma infestans , the primary vector of Chagas disease, remains challenging in the hot regions of the country. The study aims to establish a temperature-based model of development for T. infestans and explore phenological factors that could partially explain the failures in vector control within these regions of high ambient temperature. Methods We employed the Briere-1 model to describe the development time from egg-hatch to adults of T. infestans with temperature. Given that the entire developmental cycle can exceed two years under cooler temperature conditions, direct study of this duration was not undertaken. Instead, simulation was employed. For this purpose, insect cohorts encompassing all six stages (egg, N1, N2, N3, N4, N5) were concurrently raised within temperature-controlled climate chambers. The number of days required for molting between consecutive stages was recorded. Using this recorded dataset, the development time from eggs to adults was statistically simulated for various constant temperatures. The Briere-1 model was then calibrated using the dataset from each molting phase and applied to the simulated complete development cycle. The model was then used in conjunction with field temperatures from four representative localities within Bolivia to compute development times and generation intervals. A GIS approach was also used to map development times and generation intervals in the geographical distribution range of T. infestans . Findings The model suggests that the minimum temperature required for the development of T. infestans is approximately 15°C. The temperature at which its development attains maximum efficiency is around 33°C, while the threshold for lethal temperature stands at approximately 39°C. In the warmer regions of Bolivia, T. infestans exhibits an almost bivoltine cycle, with the number of yearly generations ( G ) ranging from approximately 1.5 to 2.5. In contrast, within the cooler Dry Inter-Andean Valleys, its cycle becomes univoltine or even less frequent ( G ≤1). The model could potentially offer insights into the correlations between insecticide resistance and the number of yearly generations, thereby clarifying why the control of T. infestans in hotter regions proves more challenging to achieve. Interpretation The notion of generation time arises as a pivotal consideration in the management of T. infestans , especially within Bolivia’s warmer regions. In areas marked by higher temperatures, the generation time of the vector diminishes, leading to a notable increase in the population growth rate. This, in turn, accelerates the emergence of insecticide resistance, as evidenced by the findings of this current study. Author summary In Bolivia, the bug Triatoma infestans is the main carrier of Trypanosoma cruzi , the parasite responsible for Chagas disease. This study aims to understand how these bugs develop in different temperatures and how temperature affects efforts to control Chagas disease. Experiments in controlled environments with different temperatures were carried out and results revealed that the Briere-1 model can accurately imitated how the bugs’ growth rate changes with temperature: following a sigmoid pattern, higher temperatures make the bugs grow faster up to a maximum before slowing rapidly down. Using this model, the study looked at how long it takes for a new generation of bugs to develop and therefore estimated the generation time as a function of temperature. It appeared that in warmer places, the bugs can have more than one generation in a year, which makes their population grow quickly and increases the risk of Chagas disease spreading. The study also looked at whether the bugs’ resistance to insecticides is correlated to the generation time and it appeared that areas where bugs reproduce quickly tend to have more resistance to insecticides. This research emphasizes how important it is to consider temperature when trying to control T. infestans . Indeed, in areas with higher temperatures, the bugs reproduce more quickly and show a greater tendency to develop higher levels of resistance to insecticides. This dynamic complicates efforts to control them effectively. This information holds the potential to inform the development of improved strategies to curtail the spread of Chagas disease.
Optimization of a semi-nested multiplex PCR to identify Plasmodium parasites in wild-caught Anopheles in Bolivia, and its application to field epidemiological studies
(Oxford University Press, 2008) Frédéric Lardeux; Rosenka Tejerina; Claudia Aliaga; Raùl Ursic-Bedoya; Carl Lowenberger; Tamara Chávez
Without an adequate DNA extraction protocol, the identification of Plasmodium species in whole mosquitoes by PCR is difficult because of the presence of reaction inhibitors from the insects. In this study, eight DNA extraction protocols were tested, from which a chelex-based protocol was selected. Then a semi-nested multiplex PCR technique that detects and distinguishes among the four human Plasmodium species in single mosquitoes and in pools of up to 100 mosquitoes was optimized. The technique was used to detect P. vivax in wild-caught Anopheles pseudopunctipennis from a village in the Andean valleys of Bolivia in May 2003. The prevalence of infection was 0.9%. This is the first direct evidence of P. vivax transmission by this vector in this country. The extraction and PCR technique presented here can be useful to: (1) estimate Plasmodium prevalence in Anopheles populations in low prevalence areas where large numbers of individual mosquitoes would need to be processed to obtain a reliable estimate; (2) incriminate Anopheles species as malaria vectors; (3) identify all the circulating Plasmodium species in vectors from an area; (4) detect mixed infections in mosquitoes; and (5) detect mosquitoes with low-level parasite infections.
Presence of Triatoma breyeri (Reduviidae, Triatominae) in Bolivia
(2024) Frédéric Lardeux; Alberto Llanos; Roberto Rodríguez; Luc Abate; Philippe Boussès; Rosenka Tejerina; Christian Barnabé; Lineth García
The study focuses on identifying and understanding the ecological dynamics of Triatoma breyeri in Bolivia. Morphological identification and molecular analysis using gene fragments (COI, CytB and 16S) confirms T. breyeri 's presence and its relation to other species. The species has been consistently found in the Estancia-Mataral – La Palma region since 2010 but has not spread to other regions in Bolivia. The region of occurrence is a small characteristic dry inter-Andean valley. A MaxEnt model suggests part of the Bolivian Montane Dry Forest ecoregion serves as a unique habitat within its range. The infrequent presence in Bolivia and the distance from its main range in Argentina suggest recent accidental introduction, possibly through human transport. Further research is needed to comprehend its persistence in this small area of Bolivia.
Statistical analysis of larval postspiracular filament length reveals continuous variation in Bolivian Anopheles pseudopunctipennis (Diptera: Culicidae)
(2025) Frédéric Lardeux; D. Albornoz Vásquez; Rosenka Tejerina; Claudia Aliaga; Lineth García; Libia Torrez
Abstract Anopheles pseudopunctipennis is a neotropical malaria vector widely distributed from northern Argentina and Chile to the southern United States. At the larval stage, it is characterized by posterior-lateral caudal filaments, which vary markedly in length within the same samples in Bolivia, with some individuals displaying unusually long filaments. The coexistence of individuals with relatively long and relatively short filaments raises the question of whether at least two distinct populations could be differentiated based on caudal filament length. This study examined filament-length distributions in two Bolivian dry-valley populations, El Chaco and Mataral, to determine whether variation reflects distinct subpopulations or continuous phenotypic variation within a single population. Distributions deviated from normality, exhibiting moderate skewness and tail heaviness, and the Generalized Error Distribution provided the best statistical fit. Examination of outliers and a targeted analysis of the distribution tail using multiple complementary methods showed that extreme values did not form a discrete secondary cluster but rather represented the upper continuum of the trait range. The two sites showed broadly comparable distributions, consistent with similar environmental conditions. These results emphasize the importance of using appropriate distributional models for continuous traits, highlight the occurrence of rare extreme phenotypes within otherwise homogeneous populations, and provide a baseline for future studies on the ecological and genetic determinants of caudal filament variation in An. pseudopunctipennis .