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1.
Mem Inst Oswaldo Cruz ; 114: e180544, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31038548

RESUMO

BACKGROUND: Aedes aegypti populations in Brazil have been subjected to insecticide selection pressures with variable levels and sources since 1967. Therefore, the Brazilian Ministry of Health (MoH) coordinated the activities of an Ae. aegypti insecticide resistance monitoring network (MoReNAa) from 1999 to 2012. OBJECTIVES: The objective of this study was to consolidate all information available from between 1985 and 2017 regarding the resistance status and mechanisms of Brazilian Ae. aegypti populations against the main insecticide compounds used at the national level, including the larvicide temephos (an organophosphate) and the adulticide deltamethrin (a pyrethroid). METHODS: Data were gathered from two sources: a bibliographic review of studies published from 1985 to 2017, and unpublished data produced by our team within the MoReNAa between 1998 and 2012. A total of 146 municipalities were included, many of which were evaluated several times, totalling 457 evaluations for temephos and 274 for deltamethrin. Insecticide resistance data from the five Brazilian regions were examined separately using annual records of both the MoH supply of insecticides to each state and the dengue incidence in each evaluated municipality. FINDINGS: Ae. aegypti resistance to temephos and deltamethrin, the main larvicide and adulticide, respectively, employed against mosquitoes in Brazil for a long time, was found to be widespread in the country, although with some regional variations. Comparisons between metabolic and target-site resistance mechanisms showed that one or another of these was the main component of pesticide resistance in each studied population. MAIN CONCLUSIONS: (i) A robust dataset on the assessments of the insecticide resistance of Brazilian Ae. aegypti populations performed since 1985 was made available through our study. (ii) Our findings call into question the efficacy of chemical control as the sole methodology of vector control. (iii) It is necessary to ensure that sustainable insecticide resistance monitoring is maintained as a key component of integrated vector management. (iv) Consideration of additional parameters, beyond the supply of insecticides distributed by the MoH or the diverse local dynamics of dengue incidence, is necessary to find consistent correlations with heterogeneous vector resistance profiles.


Assuntos
Aedes/efeitos dos fármacos , Dengue/prevenção & controle , Resistência a Inseticidas/efeitos dos fármacos , Inseticidas/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Nitrilos/farmacologia , Piretrinas/farmacologia , Temefós/farmacologia , Animais , Bioensaio , Brasil/epidemiologia , Dengue/epidemiologia , Dengue/transmissão , Incidência , Inseticidas/administração & dosagem , Nitrilos/administração & dosagem , Piretrinas/administração & dosagem , Temefós/administração & dosagem
2.
Mem. Inst. Oswaldo Cruz ; 114: e180544, 2019. graf
Artigo em Inglês | LILACS | ID: biblio-1002687

RESUMO

BACKGROUND Aedes aegypti populations in Brazil have been subjected to insecticide selection pressures with variable levels and sources since 1967. Therefore, the Brazilian Ministry of Health (MoH) coordinated the activities of an Ae. aegypti insecticide resistance monitoring network (MoReNAa) from 1999 to 2012. OBJECTIVES The objective of this study was to consolidate all information available from between 1985 and 2017 regarding the resistance status and mechanisms of Brazilian Ae. aegypti populations against the main insecticide compounds used at the national level, including the larvicide temephos (an organophosphate) and the adulticide deltamethrin (a pyrethroid). METHODS Data were gathered from two sources: a bibliographic review of studies published from 1985 to 2017, and unpublished data produced by our team within the MoReNAa between 1998 and 2012. A total of 146 municipalities were included, many of which were evaluated several times, totalling 457 evaluations for temephos and 274 for deltamethrin. Insecticide resistance data from the five Brazilian regions were examined separately using annual records of both the MoH supply of insecticides to each state and the dengue incidence in each evaluated municipality. FINDINGS Ae. aegypti resistance to temephos and deltamethrin, the main larvicide and adulticide, respectively, employed against mosquitoes in Brazil for a long time, was found to be widespread in the country, although with some regional variations. Comparisons between metabolic and target-site resistance mechanisms showed that one or another of these was the main component of pesticide resistance in each studied population. MAIN CONCLUSIONS (i) A robust dataset on the assessments of the insecticide resistance of Brazilian Ae. aegypti populations performed since 1985 was made available through our study. (ii) Our findings call into question the efficacy of chemical control as the sole methodology of vector control. (iii) It is necessary to ensure that sustainable insecticide resistance monitoring is maintained as a key component of integrated vector management. (iv) Consideration of additional parameters, beyond the supply of insecticides distributed by the MoH or the diverse local dynamics of dengue incidence, is necessary to find consistent correlations with heterogeneous vector resistance profiles.


Assuntos
Humanos , Resistência a Inseticidas/imunologia , Temefós/análise , Aedes , Controle de Vetores , Brasil/epidemiologia
3.
Biomed Res Int ; 2018: 6257860, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30402487

RESUMO

Background: Chemical control is still a major strategy to constrain vector density and mitigate pathogen transmission. However, insecticide overuse poses a high selective pressure, favouring the spread of resistance alleles in natural populations. In an insecticide-free environment, a fitness cost is expected in resistant insects when compared to susceptible counterparts. This study investigates whether insecticide resistance to an organophosphate (temephos) and a pyrethroid (deltamethrin) is associated with fitness traits in four Aedes aegypti wild populations sampled every three months over one year. Findings: We measured development time from larvae to adult, female survival, wing length, fecundity, and adult resistance to starvation in field insecticide resistant Ae. aegypti populations four times over a year. These results were confronted with resistance levels to temephos and deltamethrin and with potentially related mechanisms, including a kdr mutation in the pyrethroid target site. No differences in fitness cost were found after contrasting mosquitoes from the same population collected throughout a year, irrespective of differences in insecticide resistance levels. Additionally, significant differences were not observed among field populations. However, compared to the reference strain Rockefeller, field females survived significantly less. Moreover, larval development was equal or slower in three out of four field populations. In no case differences were evidenced in starvation tolerance, wing length, and fecundity. Conclusions: Overall, field resistant mosquitoes seemed to have a slight fitness disadvantage when compared with the Rockefeller susceptible strain which might represent a potential fitness cost of insecticide resistance. However, after comparing Ae. aegypti from the same population but sampled at different moments, or from different field populations, mosquito life-history traits varied independently of resistance ratios. The metabolic deviations necessary to overcome the adverse effects of insecticides may cause an energy trade-off that affects energy allocation and ultimately basic demands of insect biology. The extent of fitness cost due to insecticide resistance is critical information to delay the evolution of resistance in wild vector populations.


Assuntos
Aedes/genética , Aptidão Genética , Resistência a Inseticidas/genética , Aedes/efeitos dos fármacos , Animais , Brasil , Feminino , Fertilidade/efeitos dos fármacos , Resistência a Inseticidas/efeitos dos fármacos , Nitrilos/toxicidade , Piretrinas/toxicidade , Análise de Sobrevida , Temefós/toxicidade
4.
PLoS Negl Trop Dis ; 12(8): e0006734, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30125295

RESUMO

BACKGROUND: Resistance to pyrethroids and to the organophosphate temephos is widespread in Brazilian populations of the dengue vector, Aedes aegypti. Thereof, since 2009 Insect Growth Regulators are employed as larvicides, and malathion is used against adults. METHODOLOGY/PRINCIPAL FINDINGS: We performed laboratory selection with malathion of two A. aegypti field populations initially susceptible to this organophosphate but resistant to temephos and deltamethrin. A fixed malathion dose inducing at least 80% mortality in the first generation, was used throughout the selection process, interrupted after five generations, when the threshold of 20% mortality was reached. For each population, three experimental and two control groups, not exposed to insecticides, were kept independently. For both populations, quantitative bioassays revealed, in the selected groups, acquisition of resistance to malathion and negative impact of malathion selection on deltamethrin and temephos resistance levels. In the control groups resistance to all evaluated insecticides decreased except, unexpectedly, to deltamethrin. Analysis of the main resistance mechanisms employed routine methodologies: biochemical and molecular assays for, respectively, metabolic resistance and quantification of the NaV pyrethroid target main kdr mutations at positions 1016 and 1534. No diagnostic alteration could be specifically correlated with malathion selection, neither with the unusual deltamethrin increase in resistance levels observed in the control groups. CONCLUSIONS/SIGNIFICANCE: Our results confirm the multifactorial character of insecticide resistance and point to the need of high throughput methodologies and to the study of additional field vector populations in order to unravel resistance mechanisms.


Assuntos
Aedes/efeitos dos fármacos , Resistência a Inseticidas , Malation/farmacologia , Nitrilos/farmacologia , Piretrinas/farmacologia , Temefós/farmacologia , Animais , Bioensaio , Inseticidas/farmacologia
5.
PLoS Negl Trop Dis ; 12(3): e0006390, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29601580

RESUMO

BACKGROUND: Aedes aegypti, vector of dengue, chikungunya and Zika viruses, is found at high densities in tropical urban areas. The dissemination of this vector is partially the consequence of failures in current vector control methods, still mainly relying upon insecticides. In the State of São Paulo (SP), Brazil, public health managers employed pyrethroids against Ae. aegypti adults from 1989 to 2000, when a robust insecticide resistance monitoring system detected resistance to pyrethroids in several Ae. aegypti populations. However, pyrethroids are also the preferred compounds engaged in household applications due to their rapid knockdown effect, lower toxicity to mammals and less irritating smell. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated pyrethroid resistance in Ae. aegypti populations over the course of a decade, from 2004 to 2015, after interruption of pyrethroid public applications in SP. Qualitative bioassays with papers impregnated with a deltamethrin diagnostic dose (DD) performed with insects from seven SP municipalities and evaluated yearly from 2006 to 2014, detected resistance in most of the cases. Quantitative bioassays were also carried out with four populations in 2011, suggesting a positive correlation between resistance level and survivorship in the DD bioassays. Biochemical tests conducted with seven insect populations in 2006 and 2015, detected increasing metabolic alterations of all major classes of detoxifying enzymes, mostly of mixed function oxidases. Genotyping of the voltage-gated sodium channel (AaNaV, the pyrethroid target-site) with a TaqMan real time PCR based technique was performed from 2004 to 2014 in all seven localities. The two kdr mutations, Val1016Ile and Phe1534Cys, known to be spread throughout Brazil, were always present with a severe decrease of the susceptible allele over time. CONCLUSIONS/SIGNIFICANCE: These results are discussed in the context of public and domestic insecticide use, the necessity of implementation of a strong integrated vector control strategy and the conceptual misunderstanding between 'vector control' and 'chemical control of vectors'.


Assuntos
Aedes/efeitos dos fármacos , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Piretrinas/farmacologia , Aedes/genética , Alelos , Animais , Bioensaio/instrumentação , Bioensaio/métodos , Brasil/epidemiologia , Febre de Chikungunya/epidemiologia , Febre de Chikungunya/prevenção & controle , Febre de Chikungunya/virologia , Dengue/epidemiologia , Dengue/prevenção & controle , Dengue/virologia , Genótipo , Larva/efeitos dos fármacos , Controle de Mosquitos , Mosquitos Vetores/virologia , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/virologia
6.
PLoS Negl Trop Dis ; 12(2): e0006227, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29432488

RESUMO

BACKGROUND: In the tropics, the utilization of insecticides is still an important strategy for controlling Aedes aegypti, the principle vector of dengue, chikungunya and Zika viruses. However, increasing insecticide resistance in Ae. aegypti populations might hinder insecticide efficacy on a long-term basis. It will be important to understand the dynamics and evolution of insecticide resistance by assessing its frequency and the mechanisms by which it occurs. METHODOLOGY/PRINCIPAL FINDINGS: The insecticide resistance status of four Brazilian Ae. aegypti populations was monitored. Quantitative bioassays with the major insecticides employed in the country was performed: the adulticide deltamethrin (a pyrethroid-PY) and the larvicides, temephos (an organophosphate) and diflubenzuron (a chitin synthesis inhibitor). Temephos resistance was detected in all populations although exhibiting a slight decrease over time probably due to the interruption of field use. All vector populations were susceptible to diflubenzuron, recently introduced in the country to control Ae. aegypti. Resistance against deltamethrin was extremely high in three populations. Molecular assays investigated substitutions in the voltage gated sodium channel (NaV), the PY target site, at positions 1011, 1016 and 1534. Elevated frequencies of substitutions Val1016Ile and Phe1534Cys related to high PY resistance levels were identified. Biochemical assays detected alterations in the activities of two detoxifying enzyme classes related to metabolic resistance, glutathion-S-transferases and esterases. The results obtained were evaluated in the context of both recent insecticide use and the records of dengue incidence in each locality. CONCLUSIONS/SIGNIFICANCE: The four Ae. aegypti populations evaluated were resistant to the neurotoxic insecticides, temephos and deltamethrin. However, they were still susceptible to diflubenzuron. A probable correlation between adult insect resistance to PY and the domestic application of insecticides is discussed, pointing to the need for awareness measures regarding the correct utilization by citizens. This work aims to contribute to the efficient and rational management of Ae. aegypti control of both larvae and adults.


Assuntos
Aedes/efeitos dos fármacos , Uso de Medicamentos , Resistência a Inseticidas , Inseticidas/farmacologia , Animais , Bioensaio , Brasil , Diflubenzuron/farmacologia , Nitrilos/farmacologia , Piretrinas/farmacologia , Temefós/farmacologia
7.
PLoS Negl Trop Dis ; 11(10): e0006063, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29084225

RESUMO

Mosquito vectors lay their white eggs in the aquatic milieu. During early embryogenesis water passes freely through the transparent eggshell, which at this moment is composed of exochorion and endochorion. Within two hours the endochorion darkens via melanization but even so eggs shrink and perish if removed from moisture. However, during mid-embryogenesis, cells of the extraembryonic serosa secrete the serosal cuticle, localized right below the endochorion, becoming the third and innermost eggshell layer. Serosal cuticle formation greatly reduces water flow and allows egg survival outside the water. The degree of egg resistance to desiccation (ERD) at late embryogenesis varies among different species: Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus eggs can survive in a dry environment for ≥ 72, 24 and 5 hours, respectively. In some adult insects, darker-body individuals show greater resistance to desiccation than lighter ones. We asked if egg melanization enhances mosquito serosal cuticle-dependent ERD. Species with higher ERD at late embryogenesis exhibit more melanized eggshells. The melanization-ERD hypothesis was confirmed employing two Anopheles quadrimaculatus strains, the wild type and the mutant GORO, with a dark-brown and a golden eggshell, respectively. In all cases, serosal cuticle formation is fundamental for the establishment of an efficient ERD but egg viability outside the water is much higher in mosquitoes with darker eggshells than in those with lighter ones. The finding that pigmentation influences egg water balance is relevant to understand the evolutionary history of insect egg coloration. Since eggshell and adult cuticle pigmentation ensure insect survivorship in some cases, they should be considered regarding species fitness and novel approaches for vector or pest insects control.


Assuntos
Aedes/metabolismo , Anopheles/metabolismo , Culex/metabolismo , Melaninas/metabolismo , Óvulo/química , Óvulo/metabolismo , Animais , Cor , Dessecação , Feminino , Água/análise , Água/metabolismo
8.
Biomed Res Int ; 2016: 8603140, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27822479

RESUMO

We evaluated the efficacy of the growth regulator triflumuron (TFM) in inducing mortality and disrupting both oviposition and egg hatching in Rhodnius prolixus adult females. TFM was administered via feeding, topically or by continuous contact with impregnated surfaces. Feeding resulted in mild biological effects compared with topical and impregnated surfaces. One day after treatment, the highest mortality levels were observed with topical surface and 30 days later both topical and impregnated surfaces induced higher mortalities than feeding. Oral treatment inhibited oviposition even at lower doses, and hatching of eggs deposited by treated females was similarly affected by the three delivery modes. Topical treatment of eggs deposited by nontreated females significantly reduced hatching. However, treatment per contact of eggs oviposited by untreated females did not disrupt eclosion. Additionally, oral treatment increased the number of immature oocytes per female, and topical treatment reduced the mean size of oocytes. TFM also affected carcass chitin content, diuresis, and innate immunity of treated insects. These results suggest that TFM acts as a potent growth inhibitor of R. prolixus adult females and has the potential to be used in integrated vector control programs against hematophagous triatomine species.


Assuntos
Benzamidas/farmacologia , Inseticidas/farmacologia , Reprodução/efeitos dos fármacos , Rhodnius/efeitos dos fármacos , Animais , Quitina/metabolismo , Diurese/efeitos dos fármacos , Ovos , Métodos de Alimentação , Feminino , Imunidade Inata/efeitos dos fármacos , Oócitos/efeitos dos fármacos , Oviposição/efeitos dos fármacos
11.
Biomed Res Int ; 2016: 8603263, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27419140

RESUMO

Insecticides are still largely applied in public health to control disease vectors. In Brazil, organophosphates (OP) and pyrethroids (PY) are used against Aedes aegypti for years. Since 2009 Insect Growth Regulators (IGR) are also employed in the control of larvae. We quantified resistance to temephos (OP), deltamethrin (PY), and diflubenzuron (IGR) of A. aegypti samples from 12 municipalities distributed throughout the country, collected between 2010 and 2012. High levels of resistance to neurotoxic insecticides were detected in almost all populations: RR95 to temephos varied between 4.0 and 27.1; the lowest RR95 to deltamethrin was 13.1, and values higher than 70.0 were found. In contrast, all samples were susceptible to diflubenzuron (RR95 < 2.3). Biochemical tests performed with larvae and adults discarded the participation of acetylcholinesterase, the OP target, and confirmed involvement of the detoxifying enzymes esterases, mixed function oxidases, and glutathione-S-transferases. The results obtained were discussed taking into account the public chemical control component and the increase in the domestic use of insecticides during dengue epidemic seasons in the evaluated municipalities.


Assuntos
Aedes/efeitos dos fármacos , Aedes/fisiologia , Diflubenzuron/farmacologia , Resistência a Inseticidas/fisiologia , Inseticidas/farmacologia , Nitrilos/farmacologia , Piretrinas/farmacologia , Acetilcolinesterase/metabolismo , Aedes/metabolismo , Animais , Brasil , Vetores de Doenças , Feminino , Glutationa Transferase/metabolismo , Larva/efeitos dos fármacos , Larva/fisiologia , Masculino , Oxirredutases/metabolismo , Saúde Pública , Temefós/farmacologia
14.
Insect Biochem Mol Biol ; 69: 91-104, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26079630

RESUMO

Chagas disease or American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite, Trypanosoma cruzi. Once known as an endemic health problem of poor rural populations in Latin American countries, it has now spread worldwide. The parasite is transmitted by triatomine bugs, of which Rhodnius prolixus (Hemiptera, Reduviidae, Triatominae) is one of the vectors and a model organism. This species occurs mainly in Central and South American countries where the disease is endemic. Disease prevention focuses on vector control programs that, in general, rely intensely on insecticide use. However, the massive use of chemical insecticides can lead to resistance. One of the major mechanisms is known as metabolic resistance that is associated with an increase in the expression or activity of detoxification genes. Three of the enzyme families that are involved in this process - carboxylesterases (CCE), glutathione s-transferases (GST) and cytochrome P450s (CYP) - are analyzed in the R. prolixus genome. A similar set of detoxification genes to those of the Hemipteran Acyrthosiphon pisum but smaller than in most dipteran species was found in R. prolixus genome. All major CCE classes (43 genes found) are present but the pheromone/hormone processing class had fewer genes than usual. One main expansion was detected on the detoxification/dietary class. The phosphotriesterase family, recently associated with insecticide resistance, was also represented with one gene. One microsomal GST gene was found and the cytosolic GST gene count (14 genes) is extremely low when compared to the other hemipteran species with sequenced genomes. However, this is similar to Apis mellifera, a species known for its deficit in detoxification genes. In R. prolixus 88 CYP genes were found, with representatives in the four clans (CYP2, CYP3, CYP4 and mitochondrial) usually found in insects. R. prolixus seems to have smaller species-specific expansions of CYP genes than mosquitoes and beetles, among others. The number of R. prolixus CYP genes is similar to the hemipteran Ac. pisum, although with a bigger expansion in CYP3 and CYP4 clans, along with several gene fragments, mostly in CYP4 clan. Eleven founding members of new families were detected, consisting of ten genes in the CYP3 clan and 1 gene in the CYP4 clan. Members of these clans were proposed to have important detoxification roles in insects. The identification of CCE, GST and CYP genes is of utmost importance for directing detoxification studies on triatomines that can help insecticide management strategies in control programs.


Assuntos
Inativação Metabólica/genética , Resistência a Inseticidas/genética , Filogenia , Rhodnius/enzimologia , Rhodnius/genética , Animais , Hidrolases de Éster Carboxílico/genética , Sistema Enzimático do Citocromo P-450/genética , Genoma de Inseto , Glutationa Transferase/genética , Insetos Vetores , Inseticidas
15.
J Insect Physiol ; 83: 43-52, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26514070

RESUMO

Mosquito eggs are laid in water but freshly laid eggs are susceptible to dehydration, if their surroundings dry out at the first hours of development. During embryogenesis of different mosquito vectors the serosal cuticle, an extracellular matrix, is produced; it wraps the whole embryo and becomes part of the eggshell. This cuticle is an essential component of the egg resistance to desiccation (ERD). However, ERD is variable among species, sustaining egg viability for different periods of time. While Aedes aegypti eggs can survive for months in a dry environment (high ERD), those of Anopheles aquasalis and Culex quinquefasciatus in the same condition last, respectively, for one day (medium ERD) or a few hours (low ERD). Resistance to desiccation is determined by the rate of water loss, dehydration tolerance and total amount of water of a given organism. The ERD variability observed among mosquitoes probably derives from diverse traits. We quantified several attributes of whole eggs, potentially correlated with the rate of water loss: length, width, area, volume, area/volume ratio and weight. In addition, some eggshell aspects were also evaluated, such as absolute and relative weight, weight/area relationship (herein called surface density) and chitin content. Presence of chitin specifically in the serosal cuticle as well as aspects of endochorion external surface were also investigated. Three features could be related to differences on ERD levels: chitin content, directly related to ERD, the increase in the egg volume during embryogenesis and the eggshell surface density, which were both inversely related to ERD. Although data suggest that the amount of chitin in the eggshell is relevant for egg impermeability, the participation of other yet unidentified eggshell attributes must be considered in order to account for the differences in the ERD levels observed among Ae. aegypti, An. aquasalis and Cx. quinquefasciatus.


Assuntos
Aedes/embriologia , Anopheles/embriologia , Quitina/isolamento & purificação , Culex/embriologia , Óvulo/química , Aedes/química , Aedes/fisiologia , Animais , Anopheles/química , Anopheles/fisiologia , Culex/química , Culex/fisiologia , Dessecação , Insetos Vetores/química , Insetos Vetores/embriologia , Insetos Vetores/fisiologia , Óvulo/fisiologia , Água/metabolismo
16.
PLoS One ; 10(6): e0130719, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26107715

RESUMO

Several Aedes aegypti field populations are resistant to neurotoxic insecticides, mainly organophoshates and pyrethroids, which are extensively used as larvicides and adulticides, respectively. Diflubenzuron (DFB), a chitin synthesis inhibitor (CSI), was recently approved for use in drinking water, and is presently employed in Brazil for Ae. aegypti control, against populations resistant to the organophosphate temephos. However, tests of DFB efficacy against field Ae. aegypti populations are lacking. In addition, information regarding the dynamics of CSI resistance, and characterization of any potential fitness effects that may arise in conjunction with resistance are essential for new Ae. aegypti control strategies. Here, the efficacy of DFB was evaluated for two Brazilian Ae. aegypti populations known to be resistant to both temephos and the pyrethroid deltamethrin. Laboratory selection for DFB resistance was then performed over six or seven generations, using a fixed dose of insecticide that inhibited 80% of adult emergence in the first generation. The selection process was stopped when adult emergence in the diflubenzuron-treated groups was equivalent to that of the control groups, kept without insecticide. Diflubenzuron was effective against the two Ae. aegypti field populations evaluated, regardless of their resistance level to neurotoxic insecticides. However, only a few generations of DFB selection were sufficient to change the susceptible status of both populations to this compound. Several aspects of mosquito biology were affected in both selected populations, indicating that diflubenzuron resistance acquisition is associated with a fitness cost. We believe that these results can significantly contribute to the design of control strategies involving the use of insect growth regulators.


Assuntos
Aedes/efeitos dos fármacos , Diflubenzuron/farmacologia , Aptidão Genética/efeitos dos fármacos , Inseticidas/farmacologia , Controle de Mosquitos , Aedes/genética , Aedes/crescimento & desenvolvimento , Animais , Brasil , Quitina/biossíntese , Comportamento Alimentar/efeitos dos fármacos , Feminino , Fertilidade/efeitos dos fármacos , Insetos Vetores/efeitos dos fármacos , Insetos Vetores/genética , Insetos Vetores/crescimento & desenvolvimento , Resistência a Inseticidas/genética , Larva/efeitos dos fármacos , Longevidade/efeitos dos fármacos , Masculino , Nitrilos , Óvulo/efeitos dos fármacos , Piretrinas , Temefós
17.
PLoS Negl Trop Dis ; 9(2): e0003475, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25668559

RESUMO

INTRODUCTION: The mosquito Aedes aegypti, vector of dengue, chikungunya and yellow fever viruses, is an important target of vector control programs in tropical countries. Most mosquito surveillance programs are still based on the traditional household larval surveys, despite the availability of new trapping devices. We report the results of a multicentric entomological survey using four types of traps, besides the larval survey, to compare the entomological indices generated by these different surveillance tools in terms of their sensitivity to detect mosquito density variation. METHODS: The study was conducted in five mid-sized cities, representing variations of tropical climate regimens. Surveillance schemes using traps for adults (BG-Sentinel, Adultrap and MosquiTRAP) or eggs (ovitraps) were applied monthly to three 1 km(2) areas per city. Simultaneously, larval surveys were performed. Trap positivity and density indices in each area were calculated and regressed against meteorological variables to characterize the seasonal pattern of mosquito infestation in all cities, as measured by each of the four traps. RESULTS: The House Index was consistently low in most cities, with median always 0. Traps rarely produced null indices, pointing to their greater sensitivity in detecting the presence of Ae. aegypti in comparison to the larval survey. Trap positivity indices tend to plateau at high mosquito densities. Despite this, both indices, positivity and density, agreed on the seasonality of mosquito abundance in all cities. Mosquito seasonality associated preferentially with temperature than with precipitation even in areas where temperature variation is small. CONCLUSIONS: All investigated traps performed better than the House Index in measuring the seasonal variation in mosquito abundance and should be considered as complements or alternatives to larval surveys. Choice between traps should further consider differences of cost and ease-of-use.


Assuntos
Aedes , Insetos Vetores , Controle de Mosquitos/métodos , Aedes/virologia , Animais , Brasil , Febre de Chikungunya/transmissão , Dengue/transmissão , Feminino , Humanos , Insetos Vetores/virologia , Masculino , Densidade Demográfica , Dinâmica Populacional , Estações do Ano
19.
Rio de Janeiro; Fiocruz; 2015. 458 p.
Monografia em Português | LILACS, Coleciona SUS | ID: biblio-941632
20.
Bull World Health Organ ; 92(9): 685-9, 2014 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-25378760

RESUMO

PROBLEM: In 2010, dengue virus (DENV) serotype-4 was detected during a dengue outbreak in the Amazonian city of Boa Vista. At that time Brazil was already endemic for DENV-1, DENV-2 and DENV-3. This was the first time DENV-4 was observed in the country after it was initially detected and eliminated in 1981. APPROACH: To hinder the spread of DENV-4 throughout Brazil, standard vector control measures were intensified. Vector control professionals visited 56 837 households in 22 out of 31 districts of Boa Vista, to eliminate mosquito-breeding sites. Water storage containers were treated with the larvicide diflubenzuron, and deltamethrin was sprayed for adult Aedes aegypti mosquitoes. Fifteen days later, a second larvae survey and additional deltamethrin applications were performed. LOCAL SETTING: In Brazil, dengue vector control is managed at all three government levels. Regular surveillance of Aedes aegypti is done four to six times a year to strengthen mosquito control activities in areas with high-vector density. Educational dengue control campaigns in communities are scarce, especially between outbreaks. RELEVANT CHANGES: In spite of extensive implementation of all standard control actions recommended by the Brazilian dengue control programme, only a slight decrease in mosquito density was detected. LESSONS LEARNT: There is a need to redesign all levels of dengue control. Public consultation and engagement, behaviour change and actions that go beyond technical impositions are required. Vector control programme managers need to reflect on what constitutes good practices and whether intermittent information campaigns are effective measures for dengue prevention and control.


Assuntos
Vírus da Dengue/classificação , Dengue/prevenção & controle , Surtos de Doenças/prevenção & controle , Controle de Mosquitos/métodos , Aedes , Animais , Brasil/epidemiologia , Dengue/epidemiologia , Humanos
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