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1.
Med Vet Entomol ; 36(4): 486-495, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-35762523

RESUMEN

The urban mosquito species Aedes aegypti is the main vector of arboviruses worldwide. Mosquito control with insecticides is the most prevalent method for preventing transmission in the absence of effective vaccines and available treatments; however, the extensive use of insecticides has led to the development of resistance in mosquito populations throughout the world, and the number of epidemics caused by arboviruses has increased. Three mosquito lines with different resistance profiles to deltamethrin were isolated in French Guiana, including one with the I1016 knock-down resistant allele. Significant differences were observed in the cumulative proportion of mosquitoes with a disseminated chikungunya virus infection over time across these lines. In addition, some genes related to resistance (CYP6BB2, CYP6N12, GST2, trypsin) were variably overexpressed in the midgut at 7 days after an infectious bloodmeal in these three lines. Our work shows that vector competence for chikungunya virus varied between Ae. aegypti laboratory lines with different deltamethrin resistance profiles. More accurate verification of the functional association between insecticide resistance and vector competence remains to be demonstrated.


Asunto(s)
Aedes , Arbovirus , Virus Chikungunya , Insecticidas , Animales , Insecticidas/farmacología , Mosquitos Vectores , Resistencia a los Insecticidas/genética
2.
Mem Inst Oswaldo Cruz ; 115: e200313, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33533870

RESUMEN

BACKGROUND: Aedes aegypti is the sole vector of urban arboviruses in French Guiana. Overtime, the species has been responsible for the transmission of viruses during yellow fever, dengue, chikungunya and Zika outbreaks. Decades of vector control have produced resistant populations to deltamethrin, the sole molecule available to control adult mosquitoes in this French Territory. OBJECTIVES: Our surveillance aimed to provide public health authorities with data on insecticide resistance in Ae. aegypti populations and other species of interest in French Guiana. Monitoring resistance to the insecticide used for vector control and to other molecule is a key component to develop an insecticide resistance management plan. METHODS: In 2009, we started to monitor resistance phenotypes to deltamethrin and target-site mechanisms in Ae. aegypti populations across the territory using the WHO impregnated paper test and allelic discrimination assay. FINDINGS: Eight years surveillance revealed well-installed resistance and the dramatic increase of alleles on the sodium voltage-gated gene, known to confer resistance to pyrethroids (PY). In addition, we observed that populations were resistant to malathion (organophosphorous, OP) and alpha-cypermethrin (PY). Some resistance was also detected to molecules from the carbamate family. Finally, those populations somehow recovered susceptibility against fenitrothion (OP). In addition, other species distributed in urban areas revealed to be also resistant to pyrethroids. CONCLUSION: The resistance level can jeopardize the efficiency of chemical adult control in absence of other alternatives and conducts to strongly rely on larval control measures to reduce mosquito burden. Vector control strategies need to evolve to maintain or regain efficacy during epidemics.


Asunto(s)
Aedes/efectos de los fármacos , Insectos Vectores/genética , Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Mosquitos Vectores/efectos de los fármacos , Piretrinas/farmacología , Aedes/genética , Aedes/virología , Animales , Guyana Francesa , Insectos Vectores/efectos de los fármacos , Control de Mosquitos/métodos , Mosquitos Vectores/virología , Análisis Espacio-Temporal
3.
Mem Inst Oswaldo Cruz ; 114: e190120, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31553370

RESUMEN

BACKGROUND: In recent years, South America has suffered the burden of continuous high impact outbreaks of dengue, chikungunya and Zika. Aedes aegypti is the main mosquito vector of these arboviruses and its control is the only solution to reduce transmission. OBJECTIVES: In order to improve vector control it is essential to study mosquito population genetics in order to better estimate the population structures and the geneflow among them. METHODS: We have analysed microsatellites and knockdown resistance (kdr) mutations from a trans-border region in Amazonia between the state of Amapá (Brazil) and French Guiana (overseas territory of France), to provide further knowledge on these issues. These two countries have followed distinct vector control policies since last century. For population genetic analyses we evaluated variability in 13 well-established microsatellites loci in Ae. aegypti from French Guiana (Saint Georges and Cayenne) and Brazil (Oiapoque and Macapá). The occurrence and frequency of kdr mutations in these same populations were accessed by TaqMan genotype assays for the sites 1016 (Val/Ile) and 1534 (Phe/Cys). FINDINGS: We have detected high levels of gene flow between the closest cross-border samples of Saint-Georges and Oiapoque. These results suggest one common origin of re-colonisation for the populations of French Guiana and Oiapoque in Brazil, and a different source for Macapá, more similar to the other northern Brazilian populations. Genotyping of the kdr mutations revealed distinct patterns for Cayenne and Macapá associated with their different insecticide use history, and an admixture zone between these two patterns in Saint Georges and Oiapoque, in accordance with population genetic results. MAIN CONCLUSIONS: The present study highlights the need for regional-local vector surveillance and transnational collaboration between neighboring countries to assess the impact of implemented vector control strategies, promote timely actions and develop preparedness plans.


Asunto(s)
Aedes/efectos de los fármacos , Aedes/genética , Resistencia a los Insecticidas/genética , Mosquitos Vectores/efectos de los fármacos , Mosquitos Vectores/genética , Mutación/genética , Animales , Biodiversidad , Brasil , Guyana Francesa , Genotipo , Resistencia a los Insecticidas/efectos de los fármacos
4.
BMC Infect Dis ; 16: 318, 2016 07 08.
Artículo en Inglés | MEDLINE | ID: mdl-27390932

RESUMEN

BACKGROUND: Dengue viruses (DENV) are comprised in four related serotypes (DENV-1 to 4) and are critically important arboviral pathogens affecting human populations in the tropics. South American countries have seen the reemergence of DENV since the 1970's associated with the progressive re-infestation by the mosquito vector, Aedes aegypti. In French Guiana, DENV is now endemic with the co-circulation of different serotypes resulting in viral epidemics. Between 2009 and 2010, a predominant serotype change occurred from DENV-1 to DENV-4 suggesting a competitive displacement. The aim of the present study was to evaluate the potential role of the mosquito in the selection of the new epidemic serotype. METHODS: To test this hypothesis of competitive displacement of one serotype by another in the mosquito vector, we performed mono- and co-infections of local Ae. aegypti collected during the inter-epidemic period with both viral autochthonous epidemic serotypes and compared infection, dissemination and transmission rates. We performed oral artificial infections of F1 populations in BSL-3 conditions and analyzed infection, dissemination and transmission rates. RESULTS: When two populations of Ae. aegypti from French Guiana were infected with either serotype, no significant differences in dissemination and transmission were observed between DENV-1 and DENV-4. However, in co-infection experiments, a strong competitive advantage for DENV-4 was seen at the midgut level leading to a much higher dissemination of this serotype. Furthermore only DENV-4 was present in Ae. aegypti saliva and therefore able to be transmitted. CONCLUSIONS: In an endemic context, mosquito vectors may be infected by several DENV serotypes. Our results suggest a possible competition between serotypes at the midgut level in co-infected mosquitoes leading to a drastically different transmission potential and, in this case, favoring the competitive displacement of DENV-1 by DENV-4. This phenomenon was observed despite a similar replicative fitness in mono-infections conditions.


Asunto(s)
Aedes/virología , Coinfección/transmisión , Virus del Dengue/patogenicidad , Insectos Vectores/virología , Animales , Coinfección/virología , Dengue/epidemiología , Virus del Dengue/inmunología , Guyana Francesa , Humanos , Serogrupo , América del Sur , Replicación Viral/fisiología
5.
Mem Inst Oswaldo Cruz ; 111(9): 561-9, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27653361

RESUMEN

In French Guiana, malaria vector control and prevention relies on indoor residual spraying and distribution of long lasting insecticidal nets. These measures are based on solid epidemiological evidence but reveal a poor understanding of the vector. The current study investigated the behaviour of both vectors and humans in relation to the ongoing prevention strategies. In 2012 and 2013, Anopheles mosquitoes were sampled outdoors at different seasons and in various time slots. The collected mosquitoes were identified and screened for Plasmodium infection. Data on human behaviour and malaria episodes were obtained from an interview. A total of 3,135 Anopheles mosquitoes were collected, of which Anopheles darlingi was the predominant species (96.2%). For the December 2012-February 2013 period, the Plasmodium vivax infection rate for An. darlingi was 7.8%, and the entomological inoculation rate was 35.7 infective bites per person per three-month span. In spite of high bednet usage (95.7%) in 2012 and 2013, 52.2% and 37.0% of the participants, respectively, had at least one malaria episode. An. darlingi displayed heterogeneous biting behaviour that peaked between 20:30 and 22:30; however, 27.6% of the inhabitants were not yet protected by bednets by 21:30. The use of additional individual and collective protective measures is required to limit exposure to infective mosquito bites and reduce vector densities.


Asunto(s)
Anopheles/fisiología , Mordeduras y Picaduras de Insectos , Insectos Vectores/fisiología , Animales , Anopheles/clasificación , Anopheles/parasitología , Femenino , Bosques , Guyana Francesa , Humanos , Insectos Vectores/clasificación , Insectos Vectores/parasitología , Malaria Falciparum/transmisión , Malaria Vivax/transmisión , Densidad de Población , Estaciones del Año , Especificidad de la Especie
6.
J Med Entomol ; 52(5): 770-82, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26336249

RESUMEN

The incredible mosquito species diversity in the Neotropics can provoke major confusion during vector control programs when precise identification is needed. This is especially true in French Guiana where studies on mosquito diversity practically ceased 35 yr ago. In order to fill this gap, we propose here an updated and comprehensive checklist of the mosquitoes of French Guiana, reflecting the latest changes in classification and geographical distribution and the recognition of current or erroneous synonymies. This work was undertaken in order to help ongoing and future research on mosquitoes in a broad range of disciplines such as ecology, biogeography, and medical entomology. Thirty-two valid species cited in older lists have been removed, and 24 species have been added including 12 species (comprising two new genera and three new subgenera) reported from French Guiana for the first time. New records are from collections conducted on various phytotelmata in French Guiana and include the following species: Onirion sp. cf Harbach and Peyton (2000), Sabethes (Peytonulus) hadrognathus Harbach, Sabethes (Peytonulus) paradoxus Harbach, Sabethes (Peytonulus) soperi Lane and Cerqueira, Sabethes (Sabethinus) idiogenes Harbach, Sabethes (Sabethes) quasicyaneus Peryassú, Runchomyia (Ctenogoeldia) magna (Theobald), Wyeomyia (Caenomyiella) sp. cf Harbach and Peyton (1990), Wyeomyia (Dendromyia) ypsipola Dyar, Wyeomyia (Hystatomyia) lamellata (Bonne-Wepster and Bonne), Wyeomyia (Miamyia) oblita (Lutz), and Toxorhynchites (Lynchiella) guadeloupensis (Dyar and Knab). At this time, the mosquitoes of French Guiana are represented by 235 species distributed across 22 genera, nine tribes, and two subfamilies.


Asunto(s)
Distribución Animal , Culicidae/clasificación , Culicidae/fisiología , Animales , Femenino , Guyana Francesa , Masculino
7.
Malar J ; 13: 384, 2014 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-25260354

RESUMEN

BACKGROUND: In French Guiana, Mosquito Magnet® Liberty Plus trap baited with octenol (MMoct) has been proposed for sampling Anopheles darlingi after comparison with CDC light trap and Human landing catch (HLC). However, other available lures were not tested. The current study compared MMoct and MM baited with Lurex™ (MMlur) to HLC, and analysed entomological data from MMoct collection with malaria cases to facilitate malaria surveillance. METHODS: Two independent experiments were conducted during 2012 and 2013 in Saint-Georges town, French Guiana. The first experiment used Latin square design to compare MMoct and MMlur to HLC between 18:30 to 22:30 and 05:00 to 07:00. Parity rate was determined for An. darlingi from each sampling system. In the second experiment, a 24:00 hour collection was done for four consecutive days during the first week of each month and every four days for the rest of the month using MMoct. Portion of the 24 hour collection was dissected for parity rate. All anophelines were screened for Plasmodium infection by PCR. Data for number of malaria cases was analysed for association with density of An. darlingi. RESULTS: In the first experiment, 3,721 anopheline mosquitoes were collected over 21 nights. Of these, 95.7% was identified morphologically to five species and An. darlingi contributed 98.4%, mainly from HLC (75.1%, CI 95% [73.2-77.0]) than MMoct (14.1%, CI 95% [12.6-15.7]) and MMlur (10.8%, CI 95% [9.4-12.2]). Species richness was highest in HLC meanwhile species diversity index was greatest in MMoct. MMoct collected more parous An. darlingi than HLC (p<0.0001) and MMlur (p=0.0021). The second experiment amounted to 2035 females, 60.8% belonging to 10 species. Anopheles darlingi constituted 85.0% of the species and had parity rate of 52.3%. Specimens were uninfected with Plasmodium. Density of An. darlingi best correlated with malaria cases observed six weeks later (p=0.0016; r=0.4774). CONCLUSION: Though MMoct and MMlur performed well in sampling An. darlingi, MMoct captured more species and, therefore, would be useful for surveillance. Even if it collected mostly parous mosquitoes, MMoct proved useful in collecting entomological data required for predicting malaria emergence. It is a potential replacement for HLC.


Asunto(s)
Anopheles , Malaria/transmisión , Control de Mosquitos/instrumentación , Octanoles , Animales , Monitoreo Epidemiológico , Femenino , Guyana Francesa/epidemiología , Humanos , Modelos Lineales , Malaria/epidemiología , Malaria/prevención & control , Control de Mosquitos/métodos
8.
J Med Entomol ; 61(3): 818-823, 2024 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-38408180

RESUMEN

Arboviruses can be difficult to detect in the field due to relatively low prevalence in mosquito populations. The discovery that infected mosquitoes can release viruses in both their saliva and excreta gave rise to low-cost methods for the detection of arboviruses during entomological surveillance. We implemented both saliva and excreta-based entomological surveillance during the emergence of Zika virus (ZIKV) in French Guiana in 2016 by trapping mosquitoes around households of symptomatic cases with confirmed ZIKV infection. ZIKV was detected in mosquito excreta and not in mosquito saliva in 1 trap collection out of 85 (1.2%). One female Ae. aegypti L. (Diptera: Culicidae) was found with a ZIKV systemic infection in the corresponding trap. The lag time between symptom onset in a ZIKV-infected individual living near the trap site and ZIKV detection in this mosquito was 1 wk. These results highlight the potential of detection in excreta from trapped mosquitoes as a sensitive and cost-effective method to non invasively detect arbovirus circulation.


Asunto(s)
Aedes , Heces , Saliva , Virus Zika , Animales , Guyana Francesa , Virus Zika/aislamiento & purificación , Heces/virología , Femenino , Aedes/virología , Saliva/virología , Mosquitos Vectores/virología , Masculino , Infección por el Virus Zika/transmisión
9.
BMC Ecol ; 13: 45, 2013 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-24289184

RESUMEN

BACKGROUND: Sampling design is a key issue when establishing species inventories and characterizing habitats within highly heterogeneous landscapes. Sampling efforts in such environments may be constrained and many field studies only rely on subjective and/or qualitative approaches to design collection strategy. The region of Cacao, in French Guiana, provides an excellent study site to understand the presence and abundance of Anopheles mosquitoes, their species dynamics and the transmission risk of malaria across various environments. We propose an objective methodology to define a stratified sampling design. Following thorough environmental characterization, a factorial analysis of mixed groups allows the data to be reduced and non-collinear principal components to be identified while balancing the influences of the different environmental factors. Such components defined new variables which could then be used in a robust k-means clustering procedure. Then, we identified five clusters that corresponded to our sampling strata and selected sampling sites in each stratum. RESULTS: We validated our method by comparing the species overlap of entomological collections from selected sites and the environmental similarities of the same sites. The Morisita index was significantly correlated (Pearson linear correlation) with environmental similarity based on i) the balanced environmental variable groups considered jointly (p = 0.001) and ii) land cover/use (p-value << 0.001). The Jaccard index was significantly correlated with land cover/use-based environmental similarity (p-value = 0.001). CONCLUSIONS: The results validate our sampling approach. Land cover/use maps (based on high spatial resolution satellite images) were shown to be particularly useful when studying the presence, density and diversity of Anopheles mosquitoes at local scales and in very heterogeneous landscapes.


Asunto(s)
Anopheles , Ecosistema , Monitoreo del Ambiente/métodos , Insectos Vectores , Animales , Anopheles/parasitología , Análisis por Conglomerados , Ecología/métodos , Guyana Francesa/epidemiología , Sistemas de Información Geográfica , Insectos Vectores/parasitología , Malaria/epidemiología , Tecnología de Sensores Remotos
10.
Am J Trop Med Hyg ; 108(2): 424-427, 2023 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-36535248

RESUMEN

Anopheles darlingi is the main vector of malaria in South America. In French Guiana, malaria transmission occurs inland and along the rivers with a regular reemergence in the lower Oyapock area. Control against malaria vectors includes indoor residual spraying of deltamethrin and the distribution of long-lasting impregnated bednets. In this context, the level of resistance to pyrethroids was monitored for 4 years using CDC bottle tests in An. darlingi populations. A loss of susceptibility to pyrethroids was recorded with 30-minute knock-down measured as low as 81%. However, no pyrethroid molecular resistance was found by sequencing a 170 base pair fragment of the S6 segment of domain II of the voltage-gated sodium channel gene. Fluctuation of resistance phenotypes may be influenced by the reintroduction of susceptible alleles from sylvatic populations or by other mechanisms of metabolic resistance.


Asunto(s)
Anopheles , Insecticidas , Malaria , Piretrinas , Animales , Anopheles/genética , Guyana Francesa , Resistencia a los Insecticidas/genética , Mosquitos Vectores/genética , Malaria/prevención & control , Piretrinas/farmacología , Insecticidas/farmacología , Control de Mosquitos
11.
Trop Med Infect Dis ; 8(3)2023 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-36977169

RESUMEN

The mosquito (Diptera: Culicidae) fauna of French Guiana encompasses 242 species, of which nearly half of them belong to the genus Culex. Whereas several species of Culex are important vectors of arboviruses, only a limited number of studies focus on them due to the difficulties to morphologically identify field-caught females. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been reported as a promising method for the identification of mosquitoes. Culex females collected in French Guiana were morphologically identified and dissected. Abdomens were used for molecular identification using the COI (cytochrome oxidase 1) gene. Legs and thorax of 169 specimens belonging to 13 Culex species, (i.e., Cx. declarator, Cx. nigripalpus, Cx. quinquefasciatus, Cx. usquatus, Cx. adamesi, Cx. dunni, Cx. eastor, Cx. idottus, Cx. pedroi, Cx. phlogistus, Cx. portesi, Cx. rabanicolus and Cx. spissipes) were then submitted to MALDI-TOF MS analysis. A high intra-species reproducibility and inter-species specificity of MS spectra for each mosquito body part tested were obtained. A corroboration of the specimen identification was revealed between MALDI-TOF MS, morphological and molecular results. MALDI-TOF MS protein profiling proves to be a suitable tool for identification of neotropical Culex species and will permit the enhancement of knowledge on this highly diverse genus.

12.
Mem Inst Oswaldo Cruz ; 107(3): 429-32, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22510842

RESUMEN

Anopheles darlingi Root is the major vector of human malaria in the Neotropics and has been considered to be the sole malaria vector in French Guiana. The presence of other potential vectors suggests that malaria may be transmitted by other species under certain conditions. From 2006-2011, all anopheline specimens collected from 11 localities were assayed to determine if the Plasmodium circumsporozoite protein was present. In addition to An. darlingi, we found Anopheles oswaldoi, Anopheles intermedius and Anopheles nuneztovari specimens that were infected with Plasmodium sp. Further investigations on the behaviour and ecology of An. oswaldoi, An. intermedius and An. nuneztovari are necessary to determine their role in malaria transmission in French Guiana.


Asunto(s)
Anopheles/parasitología , Insectos Vectores/parasitología , Plasmodium falciparum/química , Plasmodium malariae/química , Plasmodium vivax/química , Proteínas Protozoarias/análisis , Animales , Anopheles/clasificación , Ensayo de Inmunoadsorción Enzimática , Femenino , Guyana Francesa , Humanos , Insectos Vectores/clasificación , Malaria/transmisión , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/aislamiento & purificación , Plasmodium vivax/aislamiento & purificación , Densidad de Población , Estaciones del Año
13.
J Am Mosq Control Assoc ; 28(4): 309-11, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23393754

RESUMEN

Throughout the early entomological campaigns in French Guiana (1900-1945), the presence of members of the Anopheles albitarsis Complex was reported in many places across the territory. However, since then no specimen has been caught despite many entomological studies conducted on the littoral and along the main rivers in places where malaria was endemic. We report here the 1st catches in the modern period of specimens of the An. albitarsis Complex in the deep rainforest. During a military intervention, Mosquito-Magnet traps and the Centers for Disease Control and Prevention light traps were used to sample malaria vectors in an illegal gold mining area and a permanent checkpoint. Members of the An. albitarsis caught were molecularly identified using DNA barcoding. In the 2 sites where An. albitarsis s.l. were caught, all specimens were An. marajoara. As An. marajoara is considered as an important malaria vector in Amazonia, the highest interest must be shown to this species in French Guiana.


Asunto(s)
Anopheles/clasificación , Anopheles/fisiología , Animales , Anopheles/genética , Demografía , Complejo IV de Transporte de Electrones/genética , Complejo IV de Transporte de Electrones/metabolismo , Guyana Francesa , Regulación Enzimológica de la Expresión Génica , Subunidades de Proteína/genética , Subunidades de Proteína/metabolismo
14.
Trop Med Int Health ; 16(1): 134-9, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21371212

RESUMEN

OBJECTIVES: To estimate the vector competence of Aedes aegypti populations sampled from distinct anthropogenic environments in French Guiana, Guadeloupe and Martinique for the strain CHIKV 06.21. METHODS: F(1)/F(2) females were orally infected at titres of 10(6) and 10(7.5) pfu/ml in blood-meals. Disseminated infection rates (DIR) of mosquitoes were estimated using indirect fluorescent antibody assay on heads' squashes, 7 or 14 days post-infection (pi). RESULTS: At a titre of 10(7.5) pfu/ml, DIR ranged from 88.9% to 100.0% and were not significantly different whether assessed at day 7 or 14 pi. At a titre of 10(6) pfu/ml, DIR observed 7 days pi ranged from 37.6 to 62.0%. CONCLUSIONS: Ae. aegypti from French Guiana and French West Indies are highly competent to transmit CHIKV. An evaluation of DIR 7 days rather than 14 days pi is adequate to estimate vector competence. The titre of 10(6) pfu/ml allows us to distinguish Ae. aegypti populations originating from distinct environments (dense or diffuse housing) by their vector competence. This assessment is a prerequisite to better evaluate the potential risk of Chikungunya outbreaks once the virus is introduced from endemic regions.


Asunto(s)
Aedes/virología , Infecciones por Alphavirus/veterinaria , Virus Chikungunya/patogenicidad , Insectos Vectores/virología , Infecciones por Alphavirus/transmisión , Animales , Virus Chikungunya/aislamiento & purificación , Susceptibilidad a Enfermedades , Conducta Alimentaria , Femenino , Guyana Francesa , Guadalupe , Martinica
15.
Mem Inst Oswaldo Cruz ; 106(3): 346-52, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21655824

RESUMEN

In French Guiana, pyrethroids and organophosphates have been used for many years against Aedes aegypti. We aimed to establish both the resistance level of Ae. aegypti and the ultra low volume spray efficacy to provide mosquito control services with practical information to implement vector control and resistance management. Resistance to deltamethrin and fenitrothion was observed. In addition, the profound loss of efficacy of AquaK'othrine® and the moderate loss of efficacy of Paluthion® 500 were recorded. Fenitrothion remained the most effective candidate for spatial application in French Guiana until its removal in December 2010. Further investigation of the mechanism of resistance to deltamethrin demonstrated the involvement of mixed-function oxidases and, to a lesser extent, of carboxylesterases. However, these observations alone cannot explain the level of insecticide resistance we observed during tube and cage tests.


Asunto(s)
Aedes , Resistencia a los Insecticidas , Insecticidas , Control de Mosquitos , Organofosfatos , Piretrinas , Aedes/enzimología , Animales , Dengue/prevención & control , Femenino , Guyana Francesa , Dosificación Letal Mediana
16.
PLoS One ; 16(1): e0243992, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33428654

RESUMEN

Insecticide resistance is a worldwide threat for vector control around the world, and Aedes aegypti, the main vector of several arboviruses, is a particular concern. To better understand the mechanisms of resistance, four isofemale strains originally from French Guiana were isolated and analysed using combined approaches. The activity of detoxification enzymes involved in insecticide resistance was assayed, and mutations located at positions 1016 and 1534 of the sodium voltage-gated channel gene, which have been associated with pyrethroid resistance in Aedes aegypti populations in Latin America, were monitored. Resistance to other insecticide families (organophosphates and carbamates) was evaluated. A large-scale proteomic analysis was performed to identify proteins involved in insecticide resistance. Our results revealed a metabolic resistance and resistance associated with a mutation of the sodium voltage-gated channel gene at position 1016. Metabolic resistance was mediated through an increase of esterase activity in most strains but also through the shifts in the abundance of several cytochrome P450 (CYP450s). Overall, resistance to deltamethrin was linked in the isofemale strains to resistance to other class of insecticides, suggesting that cross- and multiple resistance occur through selection of mechanisms of metabolic resistance. These results give some insights into resistance to deltamethrin and into multiple resistance phenomena in populations of Ae. aegypti.


Asunto(s)
Aedes/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Proteínas de Insectos/genética , Resistencia a los Insecticidas/genética , Canales de Sodio Activados por Voltaje/genética , Aedes/efectos de los fármacos , Aedes/genética , Animales , Esterasas/metabolismo , Femenino , Guyana Francesa , Técnicas de Silenciamiento del Gen , Genotipo , Inactivación Metabólica/genética , Proteínas de Insectos/antagonistas & inhibidores , Proteínas de Insectos/metabolismo , Insecticidas/farmacología , Mucosa Intestinal/metabolismo , Nitrilos/farmacología , Oligonucleótidos/metabolismo , Polimorfismo de Nucleótido Simple , Proteoma/análisis , Proteómica , Piretrinas/farmacología , Canales de Sodio Activados por Voltaje/química , Canales de Sodio Activados por Voltaje/metabolismo
17.
Pest Manag Sci ; 77(12): 5589-5598, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34398490

RESUMEN

BACKGROUND: Pyrethroid insecticides such as deltamethrin have been massively used against Aedes aegypti leading to the spread of resistance alleles worldwide. In an insecticide resistance management context, we evaluated the temporal dynamics of deltamethrin resistance using two distinct populations carrying resistant alleles at different frequencies. Three different scenarios were followed: a continuous selection, a full release of selection, or a repeated introgression with susceptible individuals. The responses of each population to these selection regimes were measured across five generations by bioassays and by monitoring the frequency of knockdown resistance (kdr) mutations and the transcription levels and copy number variations of key detoxification enzymes. RESULTS: Knockdown resistance mutations, overexpression and copy number variations of detoxification enzymes as a mechanism of metabolic resistance to deltamethrin was found and maintained under selection across generations. On comparison, the release of insecticide pressure for five generations did not affect resistance levels and resistance marker frequencies. However, introgressing susceptible alleles drastically reduced deltamethrin resistance in only three generations. CONCLUSION: The present study confirmed that strategies consisting to stop deltamethrin spraying are likely to fail when the frequencies of resistant alleles are too high and the fitness cost associated to resistance is low. In dead-end situations like in French Guiana where alternative insecticides are not available, alternative control strategies may provide a high benefit for vector control, particularly if they favor the introgression of susceptible alleles in natural populations. © 2021 Society of Chemical Industry.


Asunto(s)
Aedes , Arbovirus , Insecticidas , Piretrinas , Aedes/genética , Animales , Variaciones en el Número de Copia de ADN , Guyana Francesa , Humanos , Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Mosquitos Vectores/genética , Nueva Caledonia , Nitrilos , Piretrinas/farmacología
18.
Malar J ; 9: 80, 2010 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-20307300

RESUMEN

BACKGROUND: With an Annual Parasite Incidence (API) of 132.1, in the high and moderate risks zones, the Maroni area of French Guiana has the second highest malaria incidence of South-America after Guyana (API = 183.54) and far above Brazil (API = 28.25). Malaria transmission is occurring despite strong medical assistance and active vector control, based on general WHO recommendations. This situation is generated by two main factors that are the social and cultural characteristics of this border area, where several ethnic groups are living, and the lack of understanding of transmission dynamics of the main mosquito vector, Anopheles darlingi. In this context, entomological data collected in two villages belonging to two different ethnic groups of the French border of the Maroni River, were retrospectively analysed to find out how the mosquito bionomics are related to the malaria transmission patterns. METHODS: Data were provided by human landing catches of mosquitoes carried out each month for two years in two villages belonging to two ethnic groups, the Amerindians Wayanas and the Aloukous of African origin. The mosquitoes were sorted by species, sex, date, hour and place of collection and processed for Plasmodium sp. parasite detection. The data were compiled to provide the following variables: human biting rates (HBR), parity rates (PR), numbers of infective bites (IB), entomological inoculation rates (EIR) and numbers of infected mosquitoes surviving enough to transmit (IMT). Spatial and temporal differences of variables between locations and during the night were tested by the Kruskall-Wallis analysis of variance to find out significant variations. RESULTS: The populations of the main mosquito vector An. darlingi showed significant variations in the spatial and temporal HBR/person/night and HBR/person/hour, IB/person/month and IB/person/hour, and IMT/village/night and IMT/village/hour. In the village of Loca (Aloukous), the IMT peaked from June to August with a very low transmission during the other months. The risks were higher during the first part of the night and an EIR of 10 infective bites per person and per year was estimated. In the village of Twenke (Wayanas), high level of transmission was reported all year with small peaks in March and October. The risk was higher during the second part of the night and an EIR of 5 infective bites per person and per year was estimated. CONCLUSION: For the first time in the past 40 years, the mosquito bionomics was related to the malaria transmission patterns in French Guiana. The peak of malaria cases reported from August to October in the Maroni region is concomitant with the significant peak of An. darlingi IMT, reported from the village of Loca where transmission is higher. However, the persistent number of cases reported all year long may also be related to the transmission in the Amerindian villages. The An. darlingi bionomics for these two close populations were found significantly different and may explain why a uniform vector control method is inadequate. Following these findings, malaria prevention measures adapted to the local conditions are needed. Finally, the question of the presence of An. darlingi sub-species is raised.


Asunto(s)
Anopheles/parasitología , Mordeduras y Picaduras de Insectos , Insectos Vectores/parasitología , Malaria Falciparum/transmisión , Plasmodium falciparum/aislamiento & purificación , Animales , Anopheles/clasificación , Anopheles/fisiología , Femenino , Guyana Francesa/epidemiología , Humanos , Incidencia , Insectos Vectores/clasificación , Insectos Vectores/fisiología , Malaria Falciparum/epidemiología , Masculino , Densidad de Población , Dinámica Poblacional , Estaciones del Año
19.
Acta Trop ; 201: 105179, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31539525

RESUMEN

Natural products have proven to be an immeasurable source of bioactive compounds. The exceptional biodiversity encountered in Amazonia, alongside a rich entomofauna and frequent interactions with various herbivores is the crucible of a promising chemodiversity. This prompted us to search for novel botanical insecticides in French Guiana. As this French overseas department faces severe issues linked to insects, notably the strong incidence of vector-borne infectious diseases, we decided to focus our research on products able to control the mosquito Aedes aegypti. We tested 452 extracts obtained from 85 species originating from 36 botanical families and collected in contrasted environments against an Ae. aegypti laboratory strain susceptible to all insecticides, and a natural population resistant to both pyrethroid and organophosphate insecticides collected in Cayenne for the most active of them. Eight species (Maytenus oblongata Reissek, Celastraceae; Costus erythrothyrsus Loes., Costaceae; Humiria balsamifera Aubl., Humiriaceae; Sextonia rubra (Mez) van der Werff, Lauraceae; Piper hispidum Sw., Piperaceae; Laetia procera (Poepp.) Eichl., Salicaceae; Matayba arborescens (Aubl.) Radlk., Sapindaceae; and Cupania scrobitulata Rich., Sapindaceae) led to extracts exhibiting more than 50% larval mortality after 48 h of exposition at 100 µg/mL against the natural population and were considered active. Selectivity and phytochemistry of these extracts were therefore investigated and discussed, and some active compounds highlighted. Multivariate analysis highlighted that solvents, plant tissues, plant family and location had a significant effect on mortality while light, available resources and vegetation type did not. Through this case study we highlighted that plant defensive chemistry mechanisms are crucial while searching for novel insecticidal products.


Asunto(s)
Aedes , Insecticidas/farmacología , Extractos Vegetales/farmacología , Animales , Guyana Francesa , Larva/efectos de los fármacos , Control de Mosquitos
20.
Eur J Public Health ; 19(2): 183-8, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19221023

RESUMEN

BACKGROUND: A dengue fever outbreak occurred in the interior of French Guiana from November 2005 onwards. An investigation, with epidemiological, entomological and public health inputs, was initiated. Its objectives were to confirm the outbreak, to describe the emergence of dengue fever in the High Maroni area and to initiate a specific public health response. METHODS: The investigation was conducted in Maripasoula in February 2006, the biggest community in that part of the country. Definition criteria were used for suspected, probable and confirmed cases of dengue fever. An entomological evaluation for larvae and adult mosquitoes was carried out. Some personal and collective vector control measures were set up by the vector control team. RESULTS: This survey identified 127 suspected dengue fever cases, whereas the epidemiological surveillance system detected only six probable and confirmed cases from the same place and for the same period. The proportion of dengue fever was higher in those people who had not travelled (23.5%) than within the population that had travelled (15.3%) in the three previous months (P = 0.01). Larvae of Stegomyia aegypti were found throughout the town, and adults were captured in 90.9% of the houses. CONCLUSION: This is the first time that a dengue fever outbreak has been described beyond the coastal region of this French overseas Department.


Asunto(s)
Dengue/epidemiología , Brotes de Enfermedades , Adulto , Animales , Culicidae/virología , Dengue/diagnóstico , Dengue/etiología , Dengue/transmisión , Femenino , Guyana Francesa/epidemiología , Humanos , Masculino , Vigilancia de la Población/métodos
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