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1.
Rev. Ciênc. Méd. Biol. (Impr.) ; 21(1): 98-116, maio 05,2022. ilus, fig, tab
Article in Portuguese | LILACS | ID: biblio-1370749

ABSTRACT

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.


Subject(s)
Animals , Male , Female , Insecticide Resistance , Aedes , Mosquito Vectors/drug effects , Insecticides , Dengue/prevention & control
2.
Rev. Soc. Bras. Med. Trop ; 55: e0553, 2022. tab
Article in English | LILACS-Express | LILACS | ID: biblio-1360812

ABSTRACT

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.

3.
Article in Chinese | WPRIM | ID: wpr-940057

ABSTRACT

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.

4.
Article in Chinese | WPRIM | ID: wpr-920783

ABSTRACT

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.

5.
Rev. saúde pública (Online) ; 55: 18, 2021. tab, graf
Article in English | LILACS, BBO | ID: biblio-1289991

ABSTRACT

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.


Subject(s)
Humans , Animals , Female , Pyrethrins/pharmacology , Aedes , Brazil , Insecticide Resistance , Locomotion
6.
Rev. Soc. Bras. Med. Trop ; 54: e07072021, 2021. tab
Article in English | LILACS | ID: biblio-1351608

ABSTRACT

Abstract INTRODUCTION: Since 2013, major Cimex lectularius infestations have been detected in public shelters in Belo Horizonte (Brazil). Due to this, insecticide resistance has been investigated as one of the possible causes for the failure to control bedbugs. METHODS: Cimicids were subjected to bioassays according to the World Health Organization recommendations using deltamethrin and all commercial insecticides available for control of Cimex in Brazil. RESULTS: Cimicids were deltamethrin resistant and presented indicative of resistance to other insecticides, except for propoxur 1%. CONCLUSIONS: The commercial insecticides have a limited effect on bedbug populations, which may justify the unsatisfactory control observed in the shelters studied.


Subject(s)
Animals , Bedbugs , Ectoparasitic Infestations , Insecticides/pharmacology , Brazil , Insecticide Resistance
7.
Article in Chinese | WPRIM | ID: wpr-904629

ABSTRACT

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.

8.
Article in Chinese | WPRIM | ID: wpr-904627

ABSTRACT

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..

9.
Article in Chinese | WPRIM | ID: wpr-876712

ABSTRACT

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.

10.
Salud pública Méx ; 62(4): 432-438, jul.-ago. 2020. tab, graf
Article in Spanish | LILACS-Express | LILACS | ID: biblio-1377335

ABSTRACT

Resumen: Objetivo: Evaluar la efectividad de la mezcla de flupyradifurona 26.3 g/L y transflutrina 52.5 g/L aplicada como niebla térmica a mosquitos Aedes vectores de virus dengue, Zika y chikungunya. Material y métodos: Se colocaron grupos de 15 mosquitos de Ae. aegypti (susceptibles y resistentes a piretroides) dentro de jaulas, en sala, recámara y cocina. Posteriormente, se aplicó la mezcla de flupyradifurona y transflutrina dentro de las viviendas a una dosis de 2 y 4 mg/m3, respectivamente. Resultados: La mezcla de flupyradifurona y transflutrina causó mortalidades de 97 a 100% sobre las cepas de mosquitos Aedes y su efectividad fue la misma en los diferentes compartimentos de las viviendas. Conclusiones: La mezcla de flupyradifurona y transflutrina, aplicada en niebla térmica, es una herramienta prometedora para el control de poblaciones de mosquitos Aedes independientemente de su estado de resistencia a insecticidas.


Abstract: Objective: To evaluate the efficacy of thermal fogging of a mixture of flupyrafirudone (26.3 g/L) and transfluthrin (52.5 g/L) against dengue, Zika y chikungunya Aedes mosquito vectors. Materials and methods: Groups of 15 caged Ae. aegypti (susceptible and pyrethroid resistant) mosquitoes were placed in living room, kitchen and bedroom inside houses, after which a dose of 2 and 4 mg/m3 of flupyradifurone and transfluthrine, respectively, was applied as thermal fog. After one hour of exposure mosquitoes were transferred to the laboratory and mortality was recorded after 24 h. Results: The mixture killed 97 to 100% of mosquitoes from the strains and the efficacy was similar independently of their place within the premises. Conclusions: The mixture of flupyrafirudone and transfluthrin applied as thermal fog is a promising tool to control Aedes mosquito populations independently of the pyrethroid-insecticide resistance status.

11.
Salud pública Méx ; 62(4): 439-446, jul.-ago. 2020. tab, graf
Article in Spanish | LILACS-Express | LILACS | ID: biblio-1377336

ABSTRACT

Resumen: Objetivo: Determinar la resistencia a insecticidas en Ae. aegypti y Ae. albopictus de Tapachula, Chiapas, México. Material y métodos: Se utilizaron ovitrampas para obtener huevos de mosquitos Aedes y se realizaron pruebas de susceptibilidad (CDC) y ensayos enzimáticos con la primera generación. Resultados: Aedes aegypti mostró resistencia a deltametrina, permetrina, malatión, clorpirifos, temefos y a bendiocarb (CARB), mientras que Aedes albopictus a malatión y en menor grado a cloripirifos, temefos, permetrina y deltametrina. Ambas especies mostraron altos niveles de enzimas como citocomo P450 y glutatión S-tranferasa, mientras que los niveles de esterasas variaron por especie y sitio muestreado. Se detectó acetilcolinesterasa insensible a insecticidas en ambas especies. Conclusión: En un hábitat urbano de Tapachula, Chiapas, México donde se aplica control con insecticidas Ae. aegypti y Ae. albopictus sólo son susceptibles al propoxur.


Abstract: Objective: To determine the insecticide resistance status of Ae. aegypti and Ae. albopictus from Tapachula, México. Materials and methods: Mosquito eggs were collected with the use of ovitraps and CDC susceptibility bioassays and biochemical assays were conducted to determine resistance levels and resistance mechanisms, respectively. Results: Ae. aegypti showed resistance to deltamethrin and permethrin (PYRs), malathion, chlorpyrifos and temephos (OP), and to bendiocarb (CARB), while Ae. albopictus showed resistance to malathion and to a lesser intensity to chlorypirifos, temephos, permethrin and deltamethrin. Both species showed high levels of P450 and GSTs, while levels of esterases varied by species and collection site. Altered acethilcholinesterase was detected in both species. Conclusion: In an urban habitat from Tapachula, Chiapas, Mexico where vector control using insecticides takes place, Ae. aegypti and Ae. albopictus are only susceptible to propoxur.

12.
Mem. Inst. Oswaldo Cruz ; 115: e200313, 2020. tab, graf
Article in English | LILACS | ID: biblio-1154867

ABSTRACT

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.


Subject(s)
Animals , Pyrethrins/pharmacology , Insecticide Resistance/drug effects , Insecticide Resistance/genetics , Aedes/drug effects , Mosquito Vectors/drug effects , Insecticides/pharmacology , Mosquito Control/methods , Aedes/genetics , Spatio-Temporal Analysis , Mosquito Vectors/virology , French Guiana , Insect Vectors/drug effects , Insect Vectors/genetics
13.
Article in Chinese | WPRIM | ID: wpr-829569

ABSTRACT

Malaria was one of the major infectious diseases in Jiangsu Province, where Anopheles sinensis and An. anthropophagus are main vectors for malaria transmission. Following the concerted efforts for decades, the goal of malaria elimination was achieved in Jiangsu Province in 2019, and the vector control strategy has played a vital role during the progress towards malaria elimination in Jiangsu Province. Hereby, we review the historical distribution and ecological features of An. sinensis and An. anthropophagus and describe vector control strategies at different stages of malaria control in Jiangsu Province. In addition, the advances in the research of vector biology and control in Jiangsu Province are discussed, including vector identification, strain colonization, susceptibility to malaria parasites and insecticide resistance.

14.
Article in Chinese | WPRIM | ID: wpr-876201

ABSTRACT

Objective To investigate the resistances of larva and adult of Aedes albopictus to common insecticides in a county of Jining City, after the dengue fever outbreak in 2017, and to provide scientific support for rational use of insecticides. Methods The insecticide resistance was tested with exposure tubes for adult mosquitoes and dipping method for larvae.After collecting the larvae and breeding for one generation, the resistances of larvae were determined with the late third-instar or early fourth-instar larvae, and the resistance of adults was tested with the female mosquitoes at 3-5 days post eclosion. Results The insecticides mainly used in the county of Jining City in 2018 were pyrethroids such as permethrin, β-cyhalothrin, α-cypermethrin, and organic phosphorus pesticides such as phoxim.The median lethal concentration (LC50) values in the larva to temephos, deltamethrin, permethrin, beta-cypermethrin were 0.006 mg/L(RR=3.75), 0.021 mg/L(RR=52.50)、0.209 mg/L(RR=104.50)、0.016 mg/L (RR=17.78), with the lowest resistance to temephos and the highest to permethrin.Adult mosquitoes were sensitive to permethrin, with a knockdown rate of 97.62% and a mortality rate of 100%.When exposed to propoxur and malathion, the knockdown rates were 97.06% and 91.89%, the mortality rates were 97.06% and 93.24%.Aedes albopictus larvae were resistant to deltamethrin, α-cypermethrin, β-cyhalothrin, β-cypermethrin, with the knockdown rates of 88.00%, 95.31%, 91.04%, 97.10%, and the mortality rates were all less than 80.00%. Conclusion The larvae and adult mosquitoes of Aedes albopictus in the county of Jining City have developed different degrees of resistance to commonly used insecticides.The resistance should be under regular monitoring and the use of insecticides should be scientific and rational to delay the resistance production.

15.
Rev. bras. parasitol. vet ; 28(4): 802-806, Oct.-Dec. 2019. tab, graf
Article in English | LILACS | ID: biblio-1057988

ABSTRACT

Abstract Population explosions of the stable fly (Stomoxys calcitrans) have become a serious concern for livestock producers near sugarcane mills in some regions of Brazil due to the insect's massive reproduction on sugarcane byproducts and waste. Despite the limited efficiency of insecticides for controlling stable fly outbreaks, producers still rely on chemical control to mitigate the alarming infestations in affected areas. This study evaluated the susceptibility of S. calcitrans populations to cypermethrin in the state of Mato Grosso do Sul, Brazil. Stable flies were tested from three field populations and two colonies, established from flies previously collected at sugarcane mills. Wild flies were collected with Nzi traps in areas of sugarcane plantations. Both wild and colonized flies were exposed to eleven concentrations of cypermethrin in impregnated filter paper bioassays. All the populations proved to be resistant to cypermethrin, with resistance factors among field populations ranging from 6.8 to 38.6. The intensive use of insecticides has led to the development of pyrethroid resistance in stable fly populations in the proximities of sugarcane mills in the state of Mato Grosso do Sul.


Resumo Explosões populacionais da mosca-dos-estábulos (Stomoxys calcitrans) tornaram-se uma séria preocupação para a pecuária próxima a usinas de cana-de-açúcar em algumas regiões do Brasil, devido à massiva reprodução da mosca em resíduos e subprodutos do processamento da cana. Apesar da limitada eficiência dos inseticidas no controle dos surtos desta mosca, produtores dependem do controle químico para mitigar as alarmantes infestações nas áreas afetadas. Este estudo objetivou avaliar a suscetibilidade de populações de S. calcitrans a piretroides no estado de Mato Grosso do Sul, Brasil. Moscas-dos-estábulos de três populações de campo e duas colônias, estabelecidas a partir de moscas previamente coletadas em usinas de cana-de-açúcar, foram testadas. Moscas selvagens foram coletadas com armadilhas Nzi em áreas de cana. Moscas coletadas foram expostas a onze concentrações de cipermetrina em bioensaios com papel de filtro impregnado. Todas as populações testadas mostraram-se resistentes ao piretroide, com fatores de resistência variando de 6,8 a 38,6 nas populações de campo. O uso intensivo de inseticidas tem levado ao desenvolvimento de resistência da mosca-dos-estábulos a piretroides em populações próximas a usinas de cana-de-açúcar no estado do Mato Grosso do Sul.


Subject(s)
Animals , Pyrethrins/pharmacology , Muscidae/drug effects , Insecticides/pharmacology , Biological Assay , Brazil , Insecticide Resistance , Lethal Dose 50
16.
Rev. costarric. salud pública ; 28(1): 15-24, ene.-jun. 2019. tab
Article in Spanish | LILACS | ID: biblio-1013972

ABSTRACT

Objetivos: Determinar la resistencia de una cepa de Aedes. aegypti de Orotina a insecticidas organofosforados (temefós y malatión), y a piretroides (deltametrina, lambda cialotrina y cipermetrina). Métodos: La evaluación de la resistencia se efectuó mediante bioensayos larvarios. A partir de cada uno de los insecticidas se calculó la concentración letal 50% (CL50). También se calculó el factor de resistencia 50% (FR50) con respecto a la cepa Rockefeller, que sirvió como control susceptible. En casos de resistencia, la evaluación se repitió exponiendo previamente las larvas a butóxido de piperonilo (BP), S, S, S tributilfosforotritionato (DEF) y ácido etacrínico (AE) para establecer los mecanismos de detoxificación asociados con la resistencia. En cada caso se calculó un factor de sinergismo 50% (FS50). Resultados: La cepa Orotina mostró susceptibilidad a temefós, malatión, deltametrina y lambda cialotrina, pero mostró resistencia incipiente a cipermetrina (CL50= 0,01103 mg/L, FR50 = 5,32). Sólo el BP revertió la resistencia a este insecticida (FS50 =10,92), lo que representa un mecanismo de detoxificación asociado con el sistema citrocromo P450 monooxigenasa. Discusión: Aunque la cepa de Ae. aegyptide Orotina mostró resistencia a cipermetrina, existen otros insecticidas para los cuales fue susceptible, que brindan opciones a las autoridades de salud para su implementación en el control químico del vector. Conclusiones: El monitoreo de la resistencia es requerido para asegurar la efectividad de los insecticidas que se utilizan en el control químico.


Abstract Objectives: To determine the resistance to organophosphate (temephos and malathion) and pyrethroid (deltamethrin, lambda cyhalothrin, and cypermethrin) insecticides in a strain of Aedes aegypti from Orotina. Methods: The evaluation of the resistance was carried out by larval bioassays. Lethal concentration 50% (LC50) was calculated for each insecticide. A factor of resistance 50% (FR50) was also calculated with respect to the Rockefeller strain, which served as susceptible control. In cases of resistance, the evaluation was replicated by exposing the larvae to piperonyl butoxide (PB), S, S, S tributylphosphorotritionate (DEF), and ethacrynic acid (AE), in order to establish the detoxification mechanisms associated with the resistance. In these cases, a factor of synergism 50% (FS50) was also calculated. Results: The Orotina strain of Ae. aegyptiwas susceptible to temephos, malathion, deltamethrin and lambda cyhalothrin, but showed incipient resistance to cypermethrin (LC50 = 0.01103 mg/L, FR50 = 5.32). Only PB reversed the state of resistance (FS50 = 10.92), which suggests a detoxification mechanism associated with the citochrome P450 monooxygenase system. Discussion: Although the Ae. aegyptistrain from Orotina showed resistance to cypermethrin, it was susceptible to other insecticides, which can be used as alternative options for chemical control of the vector. Conclusions: Monitoring of resistance is required to ensure the effectiveness of insecticides used in chemical control.


Subject(s)
Humans , Insecticide Resistance , Aedes/immunology , Chikungunya virus , Public Health , Costa Rica , Dengue , Zika Virus
17.
Mem. Inst. Oswaldo Cruz ; 114: e180544, 2019. graf
Article in English | LILACS | ID: biblio-1002687

ABSTRACT

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.


Subject(s)
Humans , Insecticide Resistance/immunology , Temefos/analysis , Aedes , Vector Control of Diseases , Brazil/epidemiology
18.
Article in English | WPRIM | ID: wpr-846907

ABSTRACT

Objective: To evaluate the susceptibility of Anopheles stephensi (An. stephensi) Liston, the main malaria vector in southern Iran, to WHO recommended insecticides. Methods: Larvae of An. stephensi were collected from three different larval habitats in both urban and rural area of Bandar Abbas city and one rural area in Rudan county southern Iran. WHO standard method was used for evaluation of adult and larval mosquito susceptibility. Bendiocarb, permethrin, lambda-cyhalothrin, deltamethrin as insecticide and temephos and chlorpyriphos as larvicide were used at the diagnostic dosages recommended by WHO. Results: Findings of this study showed all larval populations of An. stephensi were completely susceptible to temephos and candidate for resistance to chlorpyriphos. Adult mosquitoes in rural areas of Bandar Abbas city were resistant to pyrethroid and carbamate insecticides. Conclusion: Comparison of the results of this survey with previous studies indicates that the resistance to pyrethroids and carbamates in this malaria endemic region is increasing. Wide use of pesticides in agriculture is certainly effective in increasing resistance. The inter-sectoral coordination and collaboration in health and agriculture seem to be necessary to manage insecticide resistance in malaria vectors.

19.
Chinese Journal of Endemiology ; (12): 476-480, 2019.
Article in Chinese | WPRIM | ID: wpr-753528

ABSTRACT

Objective To investigate the insecticide resistance levels of adult Culex pipiens quinquefasciatus to four common insecticides in Guiyang City.Methods Larvae of Culex pipiens quinquefasciatus were collected from 8 areas of Guiyang City by larval scoop method from August to September 2015,and raised in the laboratory to adult Culex pipiens quinquefasciatus.Contact tube method was used to determine the insecticide resistance levels of adult Culex pipiens quinquefasciatus to four common insecticides,and knockdown rate of 1 h and mortality rate of 24 h recovery were calculated.The resistance level was judged according to the mortality rate:< 90% was in the resistant group (R);90%-< 98% was in the potential resistant group (M);and ≥98% was in the sensitive group (S).Results The adult Culex pipiens quinquefasciatus were exposed to 7.70 g/L dichlorvos,3.30 g/L propoxur,0.25 g/L beta-cypermethrin and 0.20 g/L dehamethrin,knockdown rates of 1 h were 57.78% (52/90)-91.11% (82/90),86.67% (78/90)-100.00% (90/90),23.33% (21/90)-77.78% (70/90) and 27.78% (25/90)-88.89% (80/90),respectively;and mortality rates of 24 h recovery were 61.11% (55/90)-94.44% (85/90),90.00% (81/90)-97.78% (88/90),23.33% (21/90)-73.33% (66/90) and 21.11% (19/90)-72.22% (65/90),respectively.Conclusion Adult Culex pipiens quinquefasciatus in Guiyang City have developed some resistance to four common insecticides,in which the mosquito has a higher resistance to pyrethroid insecticides such as beta-cypermethrin and deltamethrin.

20.
Mem. Inst. Oswaldo Cruz ; 114: e190120, 2019. tab, graf
Article in English | LILACS | ID: biblio-1040624

ABSTRACT

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.


Subject(s)
Animals , Insecticide Resistance/genetics , Aedes/drug effects , Aedes/genetics , Mosquito Vectors/drug effects , Mosquito Vectors/genetics , Mutation/genetics , Brazil , Insecticide Resistance/drug effects , Biodiversity , French Guiana , Genotype
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