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The insecticide resistance is becoming increasingly severe in malaria vectors and has become one of the most important threats to global malaria elimination. Currently, malaria vectors not only have developed high resistance to conventional insecticides, including organochlorine, organophosphates, carbamates, and pyrethroids, but also have been resistant to recently used neonicotinoids and pyrrole insecticides. This article describes the current status of global insecticide resistance in malaria vectors and global insecticide resistance management strategies, analyzes the possible major challenges in the insecticide resistance management, and proposes the response actions, so as to provide insights into global insecticide resistance management and contributions to global malaria elimination.
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Introducción. El desarrollo de la resistencia a insecticidas de Aedes aegypti representa una gran amenaza para la salud pública. La vigilancia y el monitoreo de la eficacia biológica a los insecticidas y la sensibilidad de las poblaciones de Aedes aegypti es de fundamental importancia para prolongar la vida útil de estas moléculas. Objetivo. Evaluar la eficacia biológica de los insecticidas deltametrina y ciflutrina y la sensibilidad de poblaciones de Aedes aegypti a estos insecticidas durante el brote epidémico de virus del Zika en Kuna Yala, Panamá. Materiales y métodos. Se evaluó la eficacia biológica de la deltametrina y la ciflutrina, y la sensibilidad a estos insecticidas de poblaciones de la cepa Aedes aegypti Ustupo, mediante bioensayos estandarizados por la Organización Mundial de la Salud durante el brote epidémico de virus del Zika en Kuna Yala, Panamá. Resultados. En los bioensayos con Aedes aegypti Ustupo se observó posible resistencia a deltametrina y a ciflutrina con un porcentaje de mortalidad del 95,3 y 94 %, respectivamente. Se registró baja eficacia biológica con la cepa Aedes aegypti Ustupo para la deltametrina y la ciflutrina, con medias de porcentajes de mortalidad de 75 y 31,1 %, en el intradomicilio, mientras que en el peridomicilio fue de 63,7 y 26,1 %, respectivamente. Conclusión. Los resultados de este estudio representan un desafío que debe enfrentar el Programa Nacional de Control de Aedes para lograr cuidar y mantener el efecto tóxico de los insecticidas aplicados contra las poblaciones de Aedes. Es necesario que el Programa Nacional de Control de Aedes establezca unos lineamientos de manejo de la resistencia para caracterizarla y evaluar la distribución geográfica de las poblaciones afectadas. Lo anterior con el propósito de garantizar la sostenibilidad de las intervenciones antivectoriales contra las poblaciones de Aedes.
Introduction. The development of resistance to insecticides in Aedes aegypti represents a major threat to public health. Surveillance and monitoring of the biological efficacy and sensibility of Aedes aegypti populations to insecticides is fundamental to prolong the useful life of insecticide molecules. Objective. To evaluate the biological efficacy of deltamethrin and cyfluthrin and sensibility to insecticides in Aedes aegypti during the zika epidemic outbreak in Kuna Yala, Panama. Materials and methods. We assessed the biological efficacy of deltamethrin and cyfluthrin, and sensibility in the strain Aedes aegypti Ustupo using bioassays standardized by the World Health Organization during the Zika epidemic outbreak in Kuna Yala, Panama. Results. In the bioassays with Aedes aegypti Ustupo, we observed a possible resistance to deltamethrin and cyfluthrin with a mortality rate of 95,3 and 94%, respectively. The obtained results registered low biological efficacy of deltamethrin and cyfluthrin with average percentages of mortality of 75 and 31.1% in the intradomicile, and 63,7 and 26.1% in the peridomicile. Conclusion. The results of this study represent a challenge for the National Aedes Control Program to care for and maintain the toxic effect of insecticides applied against Aedes populations. There is a need for the National Aedes Control Program to establish some guidelines about resistance assessment and resistant populations' geographic distribution to guarantee the sustainability of anti-vector interventions against Aedes populations.
الموضوعات
Insecticide Resistance , Aedes , Zika Virus , Vector Control of Diseases , Dengueالملخص
Introducción. El dengue es un problema de salud pública para el departamento de La Guajira. El control se ha enfocado en el vector con el uso de insecticidas, entre ellos los organofosforados. Objetivo. Evaluar el estado de la sensibilidad a insecticidas organofosforados de quince poblaciones de Aedes aegypti (L.) en el departamento de La Guajira, Colombia. Materiales y métodos. Se realizaron bioensayos para temefos, malatión y pirimifos- metil en larvas de tercer estadio y mosquitos adultos de Ae. aegypti en los municipios de Albania, Barrancas, Dibulla, Distracción, El Molino, Fonseca, Hatonuevo, La Jagua del Pilar, Maicao, Manaure, Riohacha, San Juan del Cesar, Uribia, Urumita y Villanueva, siguiendo la metodología de la Organización Mundial de la Salud (OMS) y la técnica de botellas usando la guía de los de los Centers for Disease Control and Prevention, respectivamente. Se determinó la sensibilidad por medio de la relación de resistencia a CL50 y CL95 (RRCL50, RRCL95) para temefos y a dosis y tiempo diagnóstico para temefos, malatión y pirimifos-metil en las poblaciones de campo evaluadas, usando como control la cepa sensible Rockefeller. Resultados. Las 15 poblaciones del departamento de La Guajira son sensibles a: temefos (relación de la resistencia a CL50<5,0; relación de resistencia a CL95<5,0; 98 a 100 % de mortalidad); pirimifos-metil (99 a 100 % de mortalidad) y malatión (100 % de mortalidad). Conclusión. Con base en los resultados obtenidos, es factible el uso de temefos, malatión y pirimifos-metil para el control de Ae. aegypti en las poblaciones evaluadas.
Introduction. Dengue is a public health problem in La Guajira region. Control has focused on the vector using insecticides, including organophosphates. Objective. To evaluate the state of susceptibility to organophosphates insecticides in fifteen Aedes aegypti (L.) populations in La Guajira, Colombia. Materials and methods. We collected samples of third-instar larvae and adult mosquitoes of Ae. aegypti in the municipalities of Albania, Barrancas, Dibulla, Distracción, El Molino, Fonseca, Hatonuevo, La Jagua del Pilar, Maicao, Manaure, Riohacha, San Juan del Cesar, Uribia, Urumita, Villanueva. Bioassays for temefos, malathion, and pirimiphos-methyl were carried out following the methodology of the World Health Organization, and the bottle technique using the guidance of the Centers for Disease Control and Prevention. Susceptibility to temefos was determined through the resistance ratio between lethal concentration 50 and lethal concentration 95; for the compounds temefos, malathion and pirimiphos-methyl, susceptibility was calculated using diagnostic dose and diagnostic time in the populations evaluated. Rockefeller susceptible strain was used as a control. Results. All evaluated populations of Ae. aegypti from La Guajira were found to be susceptible to temefos (ratio resistance to CL50<5.0; ratio resistance to CL95<5.0; 98 - 100 % mortality); pirimiphosmethyl (99 - 100 % mortality), and malathion (100 % mortality). Conclusion. Based on the results, the use of temefos, malathion, and pirimiphosmethyl is feasible for the control of Ae. aegypti in the evaluated populations.
الموضوعات
Aedes , Insecticides, Organophosphate , Temefos , Insecticide Resistance , Colombia , Malathionالملخص
Objective To investigate the seasonal Aedes population fluctuation and the resistance of Aedes populations to common insecticides in Jiangsu Province in 2020, so as to provide insights into vector-borne infectious diseases control.. Methods One village was randomly sampled from each of Xinbei District of Changzhou City and Zhangjiagang County of Suzhou City in southern Jiangsu Province, Hai’an County of Nantong City and Yandu District of Yancheng City in Central Jiangsu Province, and Suining County of Xuzhou City and Sihong County of Suqian City in northern Jiangsu Province during the period between May and October, 2020. A small ponding container was sampled, and larval Aedes mosquitoes were collected using straws once each in early and late stages of each month. All larvae were bred in laboratory to adults for population identification. In addition, larval breeding were observed in all small ponding containers in and out of 30 households that were randomly sampled from six surveillance sites, and the larval mosquito density was estimated using Breteau index. Larval A. albopictus mosquitoes were sampled around Cuiyuan New Village in Jintan District of Changzhou City, and bred in laboratory to the first offspring generation, and the susceptibility of adult female mosquitoes to deltamethrin, lambda-cyhalothrin, malathion, and propoxur was tested using the filter-paper bioassay recommended by WHO. Results A total of 1 165 larval Aedes mosquitoes were captured from small ponding containers in six surveillance sites of Jiangsu Province in 2020, and all were identified as A. albopictus following eclosion. The largest number of Aedes larvae captured was found in July. A total of 1 152 households were investigated in six surveillance sites, and the mean Breteau indexes were 9.58, 13.20, 13.71, 13.20, 12.18 and 5.58 from May to October, respectively, while a high Aedes transmission risk was seen in Xinbei District of Changzhou City, with a higher Breteau index than in Suining (H = 23.667, Padjusted = 0.001) and Sihong (H = 22.500, Padjusted = 0.003) counties. The field-captured A. albopictus from Cuiyuan New Village in Jintan District of Changzhou City remained sensitive to malathion, but was resistant to propoxur, and developed high-level resistance to deltamethrin and lambda-cyhalothrin. Conclusions A. albopictus was present in southern, central and northern Jiangsu Province in 2020, and the larval density peaked in July. A. albopictus captured from Cuiyuan New Village in Jintan District of Changzhou City has developed high-level resistance to pyrethroid pesticides.
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OBJECTIVE@#To analyze the density, distribution and insecticide resistance of Aedes albopictus in Ningbo City in 2021, so as to provide insights into formulation of dengue fever control strategies.@*METHODS@#Four administrative villages were randomly selected from each county (district) in Ningbo City from April to November, 2021, to investigate the indoor population density of Aedes larvae, and the Breteau index (BI) was calculated. The population density of adult mosquitoes was investigated in residential areas, parks/bamboo forests, waste tire stacking sites/waste stations/construction sites in each county (district). On June 2021, larvae of the natural strain A. albopictus were collected from epidemic sites of dengue fever in Ningbo City in 2018, and raised in laboratory. Then, larvae and female mosquitoes without blood feeding were selected for insecticide resistance bioassays, while insecticide-sensitive strains of A. albopictus served as controls. The resistance of A. albopictus larvae to deltamethrin, beta-cypermethrin, propoxur, temephos and dichlorvos using the impregnation method, and the medium lethal concentration (LC50) and resistance ratio (RR) were calculated. The resistance of adult A. albopictus to beta-cypermethrin, permethrin, deltamethrin, propoxur and malathion was determined using the tube bioassay, and the mosquito mortality was calculated.@*RESULTS@#A total of 10 072 small water containers from 9 935 households were investigated in Ningbo City in 2021, and there were 1 276 containers with Aedes larvae detected, with an average BI of 12.89. Totally 1 422 mosquito nets were allocated and 954 female A. albopictus were captured, with an average net trapping index of 1.34 mosquitoes/(net·hour). Both larval and adult A. albopictus mosquitoes were found from April to November, and the density of larval A. albopictus peaked in September (BI = 21.21), while the density of adult A. albopictus peaked in August, with a net trapping index of 2.38 mosquitoes/(net·hour). The LC50 values of delta-methrin, beta-cypermethrin, propoxur, temephos and dichlorvos were 0.017 4, 0.000 9, 0.364 1, 0.038 1 mg/L and 0.001 6 mg/L against larvae of natural strains of A. albopicchus, with RRs of 49.66, 25.53, 9.65, 2.24 and 6.06, and the mortality rates of adult mosquitoes were 66.00% (66/100), 69.39% (68/98), 25.00% (25/100), 98.97% (96/97) and 100.00% (98/98) 24 hours post-treatment with 0.08% beta-cypermethrin, 0.03% deltamethrin, 0.4% permethrin, 0.05% propoxur, and 0.5% malathion for 24 h, respectively.@*CONCLUSIONS@#A. albopictus is widely distributed in Ningbo City, with a high population density and presents high-level resistance to common pyrethroid insecticides. The population density and insecticide resistance of A. albopictus requires to be reinforced.
الموضوعات
Animals , Female , Malathion , Temefos , Aedes , Propoxur , Permethrin , Dichlorvos , Mosquito Vectors , Larva , Dengue/prevention & controlالملخص
BACKGROUND Malaria is a public health concern in the Amazonian Region, where Anopheles darlingi is the main vector of Plasmodium spp. Several studies hypothesised the existence of cryptic species in An. darlingi, considering variations in behaviour, morphological and genetic aspects. Determining their overall genetic background for vector competence, insecticide resistance, and other elements is essential to better guide strategies for malaria control. OBJECTIVES This study aimed to evaluate the molecular diversity in genes related to behaviour and insecticide resistance, estimating genetic differentiation in An. darlingi populations from Amazonian localities in Brazil and Pacific Colombian region. METHODS We amplified, cloned and sequenced fragments of genes related to behaviour: timeless (tim) and period (per), and to insecticide resistance: voltage-gated sodium channel (Na V ) and acetylcholinesterase (ace-1) from 516 An. darlingi DNA samples from Manaus, Unini River, Jaú River and Porto Velho - Brazil, and Chocó - Colombia. We discriminated single nucleotide polymorphisms (SNPs), determined haplotypes and evaluate the phylogenetic relationship among the populations. FINDINGS The genes per, tim and ace-1 were more polymorphic than Na V . The classical kdr and ace-1 R mutations were not observed. Phylogenetic analyses suggested a significant differentiation between An. darlingi populations from Brazil and Colombia, except for the Na V gene. There was a geographic differentiation within Brazilian populations considering per and ace-1. CONCLUSIONS Our results add genetic data to the discussion about polymorphisms at population levels in An. darlingi. The search for insecticide resistance-related mechanisms should be extended to more populations, especially from localities with a vector control failure scenario.
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Background & objectives: The state of Himachal Pradesh is one of the hilly forested states of India. Warming of climate has been evidenced in the state due to the ongoing climate change which may cause the upsurge/introduction of mosquito-borne diseases. To curb disease transmission, an effective vector control strategy will be required. Methods: Insecticide susceptibility status of available malaria vectors was determined using the standard WHO method in six districts Kangra, Una, Mandi, Bilaspur, Solan and Mandi of the state. An. culicifacies and An. fluviatilis were tested against DDT (4%), malathion (5%) and deltamethrin (0.05%) using WHO insecticide susceptibility kits. Results: Overall, An. culicifacies was found resistant to DDT in all the six districts, susceptible to malathion in all districts except Bilaspur and Solan where it showed possible resistance. It was susceptible to deltamethrin in all the study districts. An. fluviatilis was resistant to DDT and susceptible to malathion and deltamethrin in Kangra and Una districts. Interpretation & conclusion: At present, indoor residual spraying (IRS) is not being undertaken in Himachal Pradesh. However, with the information generated through the present study, the state government can plan evidence-based IRS at least for focal spray in limited foci reporting malaria incidence.
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Introdução: cerca de quatro bilhões de pessoas residem em áreas com risco de dengue, uma arbovirose transmitida pelo mosquito Aedes (Stegomyia) aegypti (Linnaeus, 1762) (Insecta, Diptera, Culicidae). Na tentativa de combater esse vetor e reduzir a disseminação da dengue, o meio de controle vetorial frequentemente utilizado são os inseticidas. Entretanto, o uso indiscriminado destes no controle do mosquito está relacionado aos mecanismos de resistência desse vetor. Objetivo: mapear as evidências científicas relacionadas à resistência do mosquito A. aegypti aos inseticidas utilizados para o controle populacional. Metodologia: revisão de escopo, segundo metodologia Instituto Joana Briggs, em bases de dados indexadas: PubMed, Embase, CINAHL, Web of Science, SCOPUS e Biblioteca Virtual em Saúde. Através do mnemônico PCC (população, conceito e contexto), elaborou-se a estratégia de busca utilizando descritores do Decs e Mesh. Resultados: foram encontrados 1.631 estudos sobre a temática. Após critérios de elegibilidade e seleção, foram incluídos 30 estudos específicos sobre resistência do Aedes aegypti a inseticidas foram incluídos na revisão. A maior parte tratou de forma experimental e 28 (93,3%) estudos trabalharam o controle químico. Em relação à resistência a inseticidas, em 20 estudos (66,6%) constatou-se resistência metabólica e em 9 (30%) a resistência mediada pela alteração da variabilidade genética. Os estudos que observaram mutação não deixam claro se a mutação gênica é especificamente devido à ação mutagênica aos inseticidas. Conclusões:o A. aegypti desenvolve adaptações que lhe conferem resistência aos inseticidas, sendo que esses mecanismos de resistência estão relacionados à variabilidade genética e a adaptações metabólicas, que são transmitidas a seus descendentes ao longo das gerações. Assim, torna-se necessário um avanço nos estudos visando não apenas identificar e explicar os mecanismos de resistência, mas encontrar meios alternativos de manejo que possam controlar o inseto sem ocasionar resistência aos mesmos.
Introduction: about four billion people live in areas at risk of dengue, an arbovirus transmitted by the Aedes (Stegomyia) aegypti (Linnaeus, 1762) (Insecta, Diptera, Culicidae). To combat this vector and reduce the spread of dengue, the means of vector control often used are insecticides. However, their indiscriminate use in mosquito control is related to the resistance mechanisms of this vector. Objective: to map the scientific evidence related to the resistance of the Aedes aegypti mosquito to the insecticides used to control dengue. Methodology: scope review, according to the Joana Briggs Institute methodology, in indexed databases: PubMed, Embase, CINAHL, Web of Science, SCOPUS and Virtual Health Library. Using the mnemonic PCC (population, concept and context), a search strategy was developed using Decs and Mesh descriptors. Results: 1,631 studies on the subject were found. After eligibility and selection criteria, 30 specific studies on Aedes aegypti resistance to insecticide were included in the review . Most treated experimentally and 28 (93.3%) studies worked on chemical control. Regarding the resistance to insecticide, in 20 studies (66.6%) there was found metabolic resistance and in 9 (30%) resistance mediated by modification on the genetic variability. Studies that have looked at mutation do not make it clear whether the gene mutation is specifically due to mutagenic action of insecticides. Conclusions: Aedes aegypti develops adaptations that gives them resistance to insecticides, and these resistance mechanisms are related to genetic variability and to metabolic adaptations, which are transmitted to its descendants over generations. Thus, it is necessary to perform advance in studies aiming not only to identify and explain the resistance mechanisms, but to find alternative means of management that can control the insect without causing resistance to them.
الموضوعات
Animals , Male , Female , Insecticide Resistance , Aedes , Mosquito Vectors/drug effects , Insecticides , Dengue/prevention & controlالملخص
ObjectiveTo investigate the resistance to beta-cypermethrin in Aedes albopictus in Xuhui District， Shanghai， China， and determine the effects of insecticide components， concentration and distance on eliminating resistant population of Aedes albopictus in ultra-low volume （ULV） spray， which would provide scientific evidence for effective mosquito control strategy and rational use of beta-cypermethrin. MethodsLarval impregnation method recommended by the World Health Organization was used to determine the drug resistance in Aedes albopictus larvae to calculate the median lethal concentration （LC50） of insecticides to Aedes albopictus larvae. The resistance to insecticides in female adults of Aedes albopictus was measured by the adult mosquito contact tube method recommended by the World Health Organization， and the 24-hour mortality （%） of female mosquitoes caused by insecticides was measured. Then the 24-hour mortality （%） of resistant female adults of Aedes albopictus due to beta cypermethrin monotherapy and compound agents was calculated by ULV spray. ResultIn 2016， 2017， 2019 and 2021， the resistance ratio in Aedes albopictus larvae to beta-cypermethrin was 9.22， 68.22， 37.33 and 59.22， respectively. In 2021， the 24-hour mortality of Aedes albopictus female adults was 62.07%. ULV sprayer experiments were performed using 4.5% beta-cypermethrin （single dose） and 12.0% beta-cypermethrin-chlorpyrifos （compound dose）. The 24-hour mortality increased with the concentration of the insecticides. The overall mortality caused by compound was higher than that by single dose. The mortality were 24.24%， 31.60% and 97.83% at the concentrations of 0.045 0%， 0.067 5% and 0.090 0% for single dose， respectively， and 58.87%， 61.62% and 90.00% at the concentrations of 0.12%， 0.18% and 0.24% for compound dose， respectively. There was no significant difference in mortality when spraying distance was 10 m， 30 m and 50 m. ConclusionAedes albopictus in Xuhui District is developed varying resistance to beta-cypermethrin. It warrants to strengthen the monitoring on insecticide resistance to formulate scientific and reasonable strategy for insecticide use. and reduce the resistance level of the Aedes albopictus to beta-cypermethrin. Compound dose is recommended to improve the effect. In addition， comprehensive treatment may be adopted to reduce the resistance.
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Objective To investigate the resistance level of adult Aedes albopictus to commonly used insecticides in urban areas of Huzhou City， and analyze the trend of insecticide resistance. Methods Aedes albopictus larvae were collected from different urban areas of Huzhou City in 2019 and 2020. The larvae were reared to adults for determining resistance using the WHO standard test kits by contact tube method. Results The mortality was 97.06%‒100.00% in adult Aedes albopictus mosquitoes exposed to 0.4% beta-cypermethrin， 0.1% deltamethrin， 0.5% malathion， 0.05% propoxur and 3% permethrin in 2019. While the adult mosquitoes exposed to 0.4% beta Cypermethrin， 0.08% beta Cypermethrin， 0.03% deltamethrin， 0.4% permethrin， 0.5% malathion and 0.02% propoxur in 2020， the adjusted mortality were 98.58%， 89.09%， 85.64%， 91.34%， 91.43% and 100% respectively . When the insecticide doses on medicated paper were high， the Huzhou populations of Aedes albopictus were sensitive to beta-cypermethrin， deltamethrin， malathion and propoxur， and showed suspected resistance to permethrin. While the Aedes albopictus were exposed to low testing dose， they showed suspected resistance to beta-cypermethrin， deltamethrin， permethrin and malathion， but remained to be sensitive to propoxur. Conclusion The adult Aedes albopictus in Huzhou City from 2019 to 2020 was still sensitive to propoxur， but their resistance to malathion changes from sensitive to resistant. When the contact tube method is used for insecticide resistance， it is suggested that the accurate diagnostic dose should be obtained first before conducting further insecticide resistance tests.
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ABSTRACT Background: Chagas disease (CD) is caused by the flagellate protozoan Trypanosoma cruzi and can be carried by different species of triatomines, including Rhodnius neglectus, which is wild, well distributed in Brazil, and has formed colonies in palm trees located in urban areas of municipalities in the state of São Paulo. Chemical control has been routinely used to reduce population density, but each year, there has been an increase in species dispersion and density. This study aimed to evaluate the susceptibility of insects to insecticides used in control. Methods: The reference population was collected from Araçatuba municipality, Nilce Maia. Dilutions of deltamethrin were prepared and applied to the back of the first-stage nymphs, which were biologically synchronized. The control group received pure acetone only. Mortality was assessed after 72 h. Results: The mortality rate with respect to diagnostic dose was 100%. The susceptibility profile observed for this population showed RR50 ranging from 1.76 to 3.632. Conclusions: The populations were susceptible to the insecticides tested. It is possible that the insecticide residual effect on this ecotope has decreased the lifespan, and controlling failures may be the cause of recolonization in this environment.
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Background: Chagas disease (CD) is caused by the flagellate protozoan Trypanosoma cruzi and can be carried by different species of triatomines, including Rhodnius neglectus, which is wild, well distributed in Brazil, and has formed colonies in palm trees located in urban areas of municipalities in the state of São Paulo. Chemical control has been routinely used to reduce population density, but each year, there has been an increase in species dispersion and density. This study aimed to evaluate the susceptibility of insects to insecticides used in control. Methods: The reference population was collected from Araçatuba municipality, Nilce Maia. Dilutions of deltamethrin were prepared and applied to the back of the first-stage nymphs, which were biologically synchronized. The control group received pure acetone only. Mortality was assessed after 72 h. Results: The mortality rate with respect to diagnostic dose was 100%. The susceptibility profile observed for this population showed RR50 ranging from 1.76 to 3.632. Conclusions: The populations were susceptible to the insecticides tested. It is possible that the insecticide residual effect on this ecotope has decreased the lifespan, and controlling failures may be the cause of recolonization in this environment.
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Chagas Disease , Insecticides , Disease , Triatominaeالملخص
Mosquitoes belonging to the genus Aedes pose a significant threat to human health on a global scenario due to their role in transmission of dengue, chikungunya, zika, and yellow fever. In absence of specific medications and vaccines against these diseases, disease prevention relies on vector control. However, in today's world, vector control is facing major challenges due to the onset of insecticide resistance in mosquitoes. There are four main mechanisms of insecticide resistance, namely, behavioral resistance, reduced penetration/cuticular resistance, metabolic detoxification, and target site resistance; however, the latter two mechanisms have been studied widely in Aedes mosquitoes. Insecticide resistance in Aedes mosquitoes is widespread throughout the world. This review compiles the degree of insecticide resistance/susceptibility prevailing among different field populations of Aedes mosquitoes worldwide. In addition, the review has detailed the mechanisms providing the resistance phenomenon observed in nature in Aedes mosquitoes.
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Objective To compare the differentially expressed proteins between cypermethrin-resistant and -sensitive Culex pipiens pallens, so as to unravel the mechanism underlying the resistance to cypermethrin in Cx. p. pallens. Methods A quantitative proteomic analysis was performed among cypermethrin-sensitive and -resistant isolates of Cx. p. pallens using isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results A total of 164 differentially expressed proteins were identified between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens, including 54 up-regulated proteins and 110 down-regulated proteins. A large number of cuticular proteins, larval cuticular proteins, pupal cuticular proteins and cuticular structural constituent proteins, which are associated with cytoskeletal structure and components, were differentially expressed between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens. Thirteen proteins, which were involved in energy production and conversion, translation, ribosomal structure and biogenesis, lipid transport and metabolism, post-translational modification, protein turnover, chaperones, cytoskeleton and intracellular transportation, were validated to be differentially expressed between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens, which may serve as potential markers of cypermethrin resistance. Conclusion Multiple insecticide resistance mechanisms contribute to the resistance to cypermethrin in Cx. p. pallens, including cuticular resistance and metabolic resistance, and the cuticular protein genes and cytochrome P450 enzymes may play an important role in the resistance of Cx. p. pallens to cypermethrin.
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Objective To investigate the susceptibility of Anopheles sinensis to malathion, deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province, so as to provide the scientific basis for local malaria vector control. Methods An. sinensis was captured from Puyang County, Puyang City of Henan Province in September 2018 and July 2020, and the susceptibility of field captured An. sinensis to malathion, deltamethrin and lambda-cyhalothrin was tested using the filter-paper bioassay recommended by WHO. The insecticide resistance level was assessed based on the WHO criteria. Results In 2018 and 2010, the half knock-down times (KT50) of malathion were 91.08 min and 40.95 min for An. sinensis, with knock-down rates of 37.50% and 60.87% 60 min post-exposure to malathion and 24-hour mortality rates of 90.91% and 100%, respectively, and the insecticide resistance levels were moderately resistant (M) and susceptible (S). The KT50 of deltamethrin were 415.56 min and 341.19 min for An. sinensis in 2018 and 2020, with knock-down rates of 22.92% and 16.98% 60 min post-exposure to malathion and 24-hour mortality rates of 22.92% and 16.98%, and the insecticide resistance levels were all resistant (R). The KT50 of lambda-cyhalothrin were 164.22 min and 236.22 min for An. sinensis in 2018 and 2020, with knock-down rates of 30.39% and 38.30% 60 min postexposure to malathion and 24 h mortality rates of 19.60% and 21.28%, respectively, and the insecticide resistance levels were all R. Conclusion An. sinensis is relatively susceptible to malathion but has developed high-level resistance to deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province..
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Objective To investigate the distribution and density of Culex mosquito populations and the resistance of Culex pipiens pallens to insecticides in Jiangsu Province in 2018 and 2019. Methods During the period from June to October in 2018 and 2019, six counties (districts, cities) were sampled in southern, northern and central Jiangsu Province as surveillance sites. The density of Culex mosquitoes was measured overnight using the light trapping technique. In addition, Culex pipiens pallens mosquitoes were collected from Hai’an of Nantong City and Yandu District of Yancheng City, central Jiangsu Province, and the sensitivity of female first filial generations to dichlorodiphenyltrichloroethane (DDT), malation, proposur, beta cypermethrin and deltamethrin was tested using the standard WHO insecticide susceptibility test assay. Results A total of 104 423 Culex mosquitoes were captured in six surveillance sites of Jiangsu Province in 2018 and 2019, and Culex quinquefasciatus (49.11%), Culex pipiens pallens (28.38%), and Culex tritaeniorhynchus (21.04%) were predominant species. The density of Culex mosquitoes started to increase since early June, peaked in July and tended to be low in late October. Culex pipiens pallens mosquitoes captured from Hai’an was susceptible to malation, while those from Yandu District were moderately resistant to malation. Culex pipiens pallens mosquitoes from both Yandu and Hai’an were moderately resistant to proposur, and were resistant to DDT, beta cypermethrin and deltamethrin. Conclusions Culex quinquefasciatus, Culex pipiens pallens and Culex tritaeniorhynchus are predominant Culex species in Jiangsu Province. Culex pipiens pallens is resistant to DT, beta cypermethrin and deltamethrin in central Jiangsu Province.
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ABSTRACT OBJECTIVE: To evaluate locomotor activity in four field populations of Ae. aegypti with different insecticide resistance profiles from the state of São Paulo for two years. METHODS: This study comprised the susceptible Rockefeller strain and four populations from São Paulo, Brazil: two considered populations with "reduced susceptibility" to pyrethroids (Campinas and Marília), and two "resistant populations" (Santos and Ribeirão Preto). First, 2016 and 2017 eggs from these five populations were hatched in laboratory. Virgin females underwent experiments under laboratory conditions at 25°C, with 12:12h light/dark (LD) photoperiod; 24-hour individual activity was recorded using a locomotor activity monitor (LAM). RESULTS: In females from 2016 field populations, both resistant populations showed significant more locomotor activity than the two reduced susceptibility populations and the Rockefeller strain (p < 0.05). As for females from 2017 field populations, reduced susceptibility populations showed a significant increased locomotor activity than the Rockefeller strain, but no significant difference when compared to Santos resistant population (p > 0.05). CONCLUSIONS: Our results indicate that insecticide-resistant Ae. aegypti populations show increased locomotor activity, which may affect the transmission dynamics of their arboviruses.
الموضوعات
Humans , Animals , Female , Pyrethrins/pharmacology , Aedes , Brazil , Insecticide Resistance , Locomotionالملخص
Abstract: Sylvatic populations of Triatoma infestans represent a challenge to Chagas disease control as they are not targeted by vector control activities and may play a key role in post-spraying house reinfestation. Understanding sylvatic foci distribution and gene flow between sylvatic and domestic populations is crucial to optimize vector control interventions and elucidate the development and spread of insecticide resistance. Herein, the genetic profiles of five Andean T. infestans populations from Bolivia with distinct insecticide susceptibility profiles were compared. Multilocus genotypes based on eight microsatellites and the DNA sequence of a fragment of the cytochrome B (cytB) gene were obtained for 92 individuals. CytB haplotypes were analyzed with previously reported Bolivian T. infestans haplotypes to evaluate putative historical gene flow among populations. Each specimen was also screened for two nucleotide mutations in the sodium channel gene (kdr), related to pyrethroid resistance (L1014 and L9251). Significant genetic differentiation was observed among all populations, although individuals of admixed origin were detected in four of them. Notably, the genetic profiles of adjacent domestic and sylvatic populations of Mataral, characterized by higher levels of insecticide resistance, support their common ancestry. Only one sylvatic individual from Mataral carried the kdr mutation L1014, suggesting that this mechanism is unlikely to cause the altered insecticide susceptibility observed in these populations. However, as the resistance mutation is present in the area, it has the potential to be selected under insecticidal pressure. Genetic comparisons of these populations suggest that insecticide resistance is likely conferred by ancient trait(s) in T. infestans sylvatic populations, which are capable of invading domiciles. These results emphasize the need for stronger entomological surveillance in the region, including early detection of house invasion, particularly post-spraying, monitoring for resistance to pyrethroids and the design of integrative control actions that consider sylvatic foci around domestic settings and their dispersion dynamics.
الموضوعات
Insecticide Resistance , Triatominae , Chagas Diseaseالملخص
In the last 15 years, different types of Triatominae resistance to different insecticides have been reported; thus, resistance may be more widespread than known, requiring better characterization and delimitation, which was the aim of this review. This review was structured on a literature search of all articles from 1970 to 2015 in the PubMed database that contained the keywords Insecticide resistance and Triatominae. Out of 295 articles screened by title, 33 texts were selected for detailed analysis. Insecticide resistance of Triatomines is a complex phenomenon that has been primarily reported in Argentina and Bolivia, and is caused by different factors (associated or isolated). Insecticide resistance of Triatominae is a characteristic inherited in an autosomal and semi-dominant manner, and is polygenic, being present in both domestic and sylvatic populations. The toxicological profi le observed in eggs cannot be transposed to different stages of evolution. Different toxicological profi les exist at macro- and microgeographical levels. The insecticide phenotype has both reproductive and developmental costs. Different physiological mechanisms are involved in resistance. Studies of Triatomine resistance to insecticides highlight three defi ciencies in interpreting the obtained results: I) the vast diversity of methodologies, despite the existence of a single guiding protocol; II) the lack of information on the actual impact of resistance ratios in the fi eld; and III) the concept of the susceptibility reference lineage. Research on the biological and behavioral characteristics of each Triatominae species that has evolved resistance is required in relation to the environmental conditions of each region.
الموضوعات
Insecticide Resistance , Triatominae , Chagas Diseaseالملخص
Abstract Metabolic resistance to chemical insecticides implies a greater capacity to detoxify insecticides due to an increase in the expression of genes and/or in the activity of enzymes related to detoxification metabolism. The insect integument is known to participate as the cuticular penetration factor of resistance, but recently this tissue was also linked with metabolic resistance due to P450-dependent detoxification in the Chagas disease vector Triatoma infestans. The objectives of this study were i) to name and classify all P450s known to date in T. infestans, ii) to characterise one of them, CYP4PR1, representing the first member of a new cytochrome P450 subfamily described in insects, and iii) to investigate the potential role of CYP4PR1 in metabolic resistance to deltamethrin in T. infestans. We found that CYP4PR1 is expressed almost exclusively in the integument tissue, and its expression was not induced by deltamethrin. Knockdown of CYP4PR1 by RNA interference in pyrethroid-resistant nymphs caused a significant increment in insect mortality after topical application of two different doses of deltamethrin. These results support the role of the integument on metabolic resistance and suggest that CYP4PR1 might contribute to resistance in integument tissue of T. infestans.