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1.
An Acad Bras Cienc ; 92(1): e20180569, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32321015

RESUMO

The essential oils obtained by hydrodistillation from fresh leaves of Vitex agnus-castus and Ocimum campechianum, and from fresh inflorescences of Ocimum carnosum were analysed by GC-FID and GC-MS. The major components of V. agnus-castus essential oil were identified as 1,8-cineole (47.9%), terpinyl α-acetate (11.6%), sabinene (11.2%) and caryophyllene oxide (9.7%), while in the O. campechianum essential oil were eugenol (72.1%), ß-elemene (6.8%), (E)-caryophyllene (6.4%) and bicyclogermacrene (5.2%). Linalool (79.0%), α-epi-cadinol (5.4%), terpinen-4-ol (3.2%) and 1,8-cineole (2.8%) were the major constituents in the O. carnosum essential oil. The essential oils were subsequently evaluated for their larvicidal and cytotoxic activities. Larval bioassay against Aedes aegypti of V. agnus-castus, O. campechianum and O. carnosum essential oils showed LC50 values of 97.55 ± 0.35, 81.45 ± 0.35 and 109.49 ± 0.35 µg/mL, respectively. The in vitro cytotoxic activities of the essential oils has been evaluated on breast adenocarcinoma (MCF-7), lung carcinoma (NCI-H292), pro-myelocytic leukemia (HL-60), and cervical adenocarcinoma (HEP-2) human cell lines, and pro-myelocytic leukemia cells lines (HL-60) were found to be the most sensitive to all the essential oils tested than the others. This is the first report on larvicidal and cytotoxic activities of these essential oils.


Assuntos
Aedes/efeitos dos fármacos , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Ocimum/química , Óleos Voláteis/farmacologia , Óleos Vegetais/farmacocinética , Vitex/química , Animais , Bioensaio , Linhagem Celular Tumoral/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Inseticidas/isolamento & purificação , Óleos Voláteis/química , Óleos Voláteis/isolamento & purificação , Folhas de Planta/química , Óleos Vegetais/química , Testes de Toxicidade , Vitex/classificação
2.
Aquat Toxicol ; 222: 105474, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32259658

RESUMO

Larval toxicity of ethanolic extract of C. parvula (Ex-Cp) was prominent in the second and the third instars at the maximum lethal dosage of 100 ppm with 98 and 97 % mortality rate respectively. The LC50 and LC90 was displayed at 43 ppm and 88 ppm dosage respectively. Correspondingly, the sub-lethal dosage (65 ppm) of Ex-Cp significantly alters the carboxylesterase (α and ß), GST and CYP450 enzyme level in both III and IV instar larvae in dose-dependent manner. Similarly, the Ex-Cp displayed significant repellent activity (97 %) with a maximum level of protection time (210 min). Photomicrography assay of Ex-Cp (65 ppm) were toxic to dengue larvae as compared to control. The non-target toxicity of Ex-Cp against the beneficial mosquito predators displayed less toxicity at the maximum dosage of 600 ppm as compared to Temephos. Thus the present research delivers the target and non-target toxicity of red algae C. parvula against the dengue mosquito vector.


Assuntos
Aedes/efeitos dos fármacos , Dengue , Repelentes de Insetos/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Extratos Vegetais/farmacologia , Rodófitas/química , Aedes/virologia , Animais , Organismos Aquáticos/efeitos dos fármacos , Carboxilesterase/metabolismo , Dengue/virologia , Relação Dose-Resposta a Droga , Repelentes de Insetos/isolamento & purificação , Repelentes de Insetos/toxicidade , Larva/efeitos dos fármacos , Larva/enzimologia , Dose Letal Mediana , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/toxicidade , Poluentes Químicos da Água/toxicidade
3.
Infect Dis Poverty ; 9(1): 23, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32114983

RESUMO

BACKGROUND: In the Republic of Congo, with two massive outbreaks of chikungunya observed this decade, little is known about the insecticide resistance profile of the two major arbovirus vectors Aedes aegypti and Aedes albopictus. Here, we established the resistance profile of both species to insecticides and explored the resistance mechanisms to help Congo to better prepare for future outbreaks. METHODS: Immature stages of Ae. aegypti and Ae. albopictus were sampled in May 2017 in eight cities of the Republic of the Congo and reared to adult stage. Larval and adult bioassays, and synergist (piperonyl butoxide [PBO]) assays were carried out according to WHO guidelines. F1534C mutation was genotyped in field collected adults in both species and the polymorphism of the sodium channel gene assessed in Ae. aegypti. RESULTS: All tested populations were susceptible to temephos after larval bioassays. A high resistance level was observed to 4% DDT in both species countrywide (21.9-88.3% mortality). All but one population (Ae. aegypti from Ngo) exhibited resistance to type I pyrethroid, permethrin, but showed a full susceptibility to type II pyrethroid (deltamethrin) in almost all locations. Resistance was also reported to 1% propoxur in Ae. aegypti likewise in two Ae. albopictus populations (Owando and Ouesso), and the remaining were fully susceptible. All populations of both species were fully susceptible to 1% fenitrothion. A full recovery of susceptibility was observed in Ae. aegypti and Ae. albopictus when pre-exposed to PBO and then to propoxur and permethrin respectively. The F1534C kdr mutation was not detected in either species. The high genetic variability of the portion of sodium channel spanning the F1534C in Ae. aegypti further supported that knockdown resistance probably play no role in the permethrin resistance. CONCLUSIONS: Our study showed that both Aedes species were susceptible to organophosphates (temephos and fenitrothion), while for other insecticide classes tested the profile of resistance vary according to the population origin. These findings could help to implement better and efficient strategies to control these species in the Congo in the advent of future arbovirus outbreaks.


Assuntos
Aedes/efeitos dos fármacos , Febre de Chikungunya/prevenção & controle , Resistência a Inseticidas , Inseticidas/farmacologia , Piretrinas/farmacologia , Aedes/virologia , Animais , Congo , Variação Genética , Proteínas de Insetos/genética , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/virologia
4.
Infect Dis Poverty ; 9(1): 30, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32183909

RESUMO

BACKGROUND: As of 2015 thousands of refugees are being hosted in temporary refugee camps in Greece. Displaced populations, travelling and living under poor conditions with limited access to healthcare are at a high risk of exposure to vector borne disease (VBD). This study sought to evaluate the risk for VBD transmission within refugee camps in Greece by analyzing the mosquito and sand fly populations present, in light of designing effective and efficient context specific vector and disease control programs. METHODS: A vector/pathogen surveillance network targeting mosquitoes and sand flies was deployed in four temporary refugee camps in Greece. Sample collections were conducted bi-weekly during June-September 2017 with the use of Centers for Disease Control (CDC) light traps and oviposition traps. Using conventional and molecular diagnostic tools we investigated the mosquito/sand fly species composition, population dynamics, pathogen infection rates, and insecticide resistance status in the major vector species. RESULTS: Important disease vectors including Anopheles sacharovi, Culex pipiens, Aedes albopictus and the Leishmania vectors Phlebotomus neglectus, P. perfiliewi and P. tobbi were recorded in the study refugee camps. No mosquito pathogens (Plasmodium parasites, flaviviruses) were detected in the analysed samples yet high sand fly Leishmania infection rates are reported. Culex pipiens mosquitoes displayed relatively high knock down resistance (kdr) mutation allelic frequencies (ranging from 41.0 to 63.3%) while kdr mutations were also detected in Ae. albopictus populations, but not in Anopheles and sand fly specimens. No diflubenzuron (DFB) mutations were detected in any of the mosquito species analysed. CONCLUSIONS: Important disease vectors and pathogens in vectors (Leishmania spp.) were recorded in the refugee camps indicating a situational risk factor for disease transmission. The Cx. pipiens and Ae. albopictus kdr mutation frequencies recorded pose a potential threat against the effectiveness of pyrethroid insecticides in these settings. In contrast, pyrethroids appear suitable for the control of Anopheles mosquitoes and sand flies and DFB for Cx. pipiens and Ae. albopictus larvicide applications. Targeted actions ensuring adequate living conditions and the establishment of integrated vector-borne disease surveillance programs in refugee settlements are essential for protecting refugee populations against VBDs.


Assuntos
Insetos Vetores/efeitos dos fármacos , Insetos Vetores/genética , Resistência a Inseticidas/genética , Leishmania , Controle de Mosquitos , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Dinâmica Populacional , Campos de Refugiados , Aedes/efeitos dos fármacos , Aedes/genética , Animais , Anopheles/efeitos dos fármacos , Anopheles/genética , Culex/efeitos dos fármacos , Culex/genética , Feminino , Grécia , Leishmania/genética , Leishmania/patogenicidade , Leishmaniose/epidemiologia , Phlebotomus/efeitos dos fármacos , Phlebotomus/genética , Psychodidae
5.
PLoS Negl Trop Dis ; 14(3): e0007753, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32176693

RESUMO

BACKGROUND: Resistance to pyrethroid insecticides in Aedes aegypti has become widespread after almost two decades of the frequent use of these pesticides to reduce arbovirus transmission. Despite this resistance, pyrethroids continue to be used because they are relatively inexpensive and have low human toxicity. Resistance management has been proposed as a way to retain the use of pyrethroids in natural populations. A key component of resistance management is the assumption that negative fitness is associated with resistance alleles such that resistance alleles will decline in frequency when the insecticides are removed. At least three studies in Ae. aegypti have demonstrated a decrease in pyrethroid resistance once the insecticide has been removed. METHODS/PRINCIPAL FINDINGS: The present study aims to evaluate variation in the loss of pyrethroid resistance among newly established laboratory populations of Ae. aegypti from Mexico. Eight field collections were maintained for up to eight generations, and we recorded changes in the frequencies of the mutations at the V1,016I locus and at the F1,534C locus in the voltage-gated sodium channel gene (VGSC). I1,016 and C1,534 confer resistance. We also examined resistance ratios (RR) with type 1 and 2 pyrethroids. CONCLUSIONS/SIGNIFICANCE: We demonstrate that, in general, the frequency of the Ae. aegypti pyrethroid-resistance alleles I1,016 and C1,534 decline when they are freed from pyrethroid pressure in the laboratory. However, the pattern of decline is strain dependent. In agreement with earlier studies, the RR was positively correlated with the frequencies of the resistance allele I1,016 and showed significant protection against permethrin, and deltamethrin, whereas F1,534C showed protection against permethrin but not against deltamethrin.


Assuntos
Aedes/efeitos dos fármacos , Aedes/crescimento & desenvolvimento , Resistência a Inseticidas , Inseticidas/farmacologia , Mutação , Piretrinas/farmacologia , Canais de Sódio Disparados por Voltagem/genética , Animais , Feminino , Frequência do Gene , Aptidão Genética , México , Seleção Genética , Canais de Sódio Disparados por Voltagem/metabolismo
6.
Rev Soc Bras Med Trop ; 53: e20190018, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187329

RESUMO

INTRODUCTION: The larvicidal potential of Saussurea costus (Falc.) Lipsch. was studied against the early 4th instar larvae of Anopheles stephensi Liston., Aedes aegypti Linn.,and Culex quinquefasciatus Say. because of the emergence of mosquito resistance to conventional synthetic insecticides. METHODS: At concentrations of 12.5-200 ppm, larvicidal activities were studied under laboratory conditions. RESULTS: After 24 h of exposure, the methanol extract of the roots recorded the highest larvicidal activity against An. stephensi, with LC50 and LC90values of 7.96 and 34.39 ppm, respectively. CONCLUSIONS: We are developing potent larvicidal compound(s) from S. costus for controlling the mosquito larval population.


Assuntos
Aedes/efeitos dos fármacos , Anopheles/efeitos dos fármacos , Culex/efeitos dos fármacos , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Extratos Vegetais/farmacologia , Saussurea/química , Animais , Inseticidas/isolamento & purificação
7.
Parasit Vectors ; 13(1): 53, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32033619

RESUMO

BACKGROUND: Aedes-borne diseases such as dengue and chikungunya constitute constant threats globally. In Tanzania, these diseases are transmitted by Aedes aegypti, which is widely distributed in urban areas, but whose ecology remains poorly understood in small towns and rural settings. METHODS: A survey of Ae. aegypti aquatic habitats was conducted in and around Ifakara, a fast-growing town in south-eastern Tanzania. The study area was divided into 200 × 200 m search grids, and habitats containing immature Aedes were characterized. Field-collected Ae. aegypti were tested for susceptibility to common public health insecticides (deltamethrin, permethrin, bendiocarb and pirimiphos-methyl) in the dry and rainy seasons. RESULTS: Of 1515 and 1933 aquatic habitats examined in the dry and rainy seasons, 286 and 283 contained Aedes immatures, respectively (container index, CI: 18.9-14.6%). In the 2315 and 2832 houses visited in the dry and rainy seasons, 114 and 186 houses had at least one Aedes-positive habitat, respectively (house index, HI: 4.9-6.6%). The main habitat types included: (i) used vehicle tires and discarded containers; (ii) flowerpots and clay pots; and (iii) holes made by residents on trunks of coconut trees when harvesting the coconuts. Used tires had highest overall abundance of Ae. aegypti immatures, while coconut tree-holes had highest densities per habitat. Aedes aegypti adults were susceptible to all tested insecticides in both seasons, except bendiocarb, against which resistance was observed in the rainy season. CONCLUSIONS: To our knowledge, this is the first study on ecology and insecticide susceptibility of Ae. aegypti in Ifakara area, and will provide a basis for future studies on its pathogen transmission activities and control. The high infestation levels observed indicate significant risk of Aedes-borne diseases, requiring immediate action to prevent potential outbreaks in the area. While used tires, discarded containers and flowerpots are key habitats for Ae. aegypti, this study also identified coconut harvesting as an important risk factor, and the associated tree-holes as potential targets for Aedes control. Since Ae. aegypti mosquitoes in the area are still susceptible to most insecticides, effective control could be achieved by combining environmental management, preferably involving communities, habitat removal and insecticide spraying.


Assuntos
Aedes , Distribuição Animal , Ecossistema , Inseticidas , Aedes/efeitos dos fármacos , Animais , Febre de Chikungunya/transmissão , Cidades , Doenças Transmissíveis/transmissão , Dengue/transmissão , Insetos Vetores/efeitos dos fármacos , Inseticidas/farmacologia , População Rural , Estações do Ano , Tanzânia
8.
J Agric Food Chem ; 68(10): 3061-3070, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32059103

RESUMO

Pyrethroids are one of the most commonly used classes of insecticides, and their acid and alcohol components are esterase degradation products, usually considered to be biologically inactive. In this study, it was found that several pyrethroid acids had a spatial repellent activity that was greater than DEET, often more active than the parent pyrethroids, and showed little cross resistance in a pyrethroid-resistant Puerto Rico strain of Aedes aegypti mosquitoes. Further investigation revealed that the acids can synergize not only contact repellent standards but also other pyrethroid components as well as the parent pyrethroids themselves. Synergism by the pyrethroid acids is expressed as both increased spatial repellency and vapor toxicity as well as human bite protection. Electrophysiological studies confirmed that pyrethroid acids (100 µM) had no effect on neuronal discharge in larval Drosophila melanogaster CNS and were detected by electroantennography, and there was little resistance to olfactory sensing of these acids in antennae from Puerto Rico strain mosquitoes carrying kdr mutations. Thus, the data suggest that the pyrethroid acids have a different mode of action than the parent pyrethroids, unrelated to the voltage-sensitive sodium channel. The results highlight the potential of pyrethroid acids to be useful in future repellent formulations.


Assuntos
Aedes/efeitos dos fármacos , Repelentes de Insetos/toxicidade , Piretrinas/química , Piretrinas/toxicidade , Ácidos/química , Ácidos/toxicidade , Aedes/genética , Álcoois/química , Álcoois/toxicidade , Animais , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/crescimento & desenvolvimento , Sinergismo Farmacológico , Repelentes de Insetos/química , Resistência a Inseticidas , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Estrutura Molecular , Controle de Mosquitos , Porto Rico
9.
Rev Soc Bras Med Trop ; 53: e20190489, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049207

RESUMO

INTRODUCTION: In Brasilia, pyriproxyfen (PPF; 0.01 mg/L) has been used for the larval control of Aedes aegypti mosquitoes since 2016. Information on the susceptibility of Ae. aegypti to PPF, and the development of resistance in populations from the Federal District of Brazil (FD) is limited. It is essential to monitor the susceptibility of Ae. aegypti to insecticides in order to improve vector control strategies. This study aimed to evaluate the susceptibility of Ae. aegypti populations from five areas of Brasilia to PPF. METHODS: We performed dose-response tests to estimate the emergence inhibition and resistance ratio of each field population, including the Rockefeller reference population. We also analyzed egg positivity, and the density and mortality of larvae and pupae. RESULTS: Populations from Vila Planalto (RR50=1.7), Regiment Guards Cavalry (RR50=2.5), and Sub-secretary of Justice Complex (RR50=3.7) presented high susceptibility to PPF, while the RR values of populations from Lago Norte (RR50=7.7) and Varjão (RR50=5.9) were moderately high, suggesting the emergence of insipient resistance to PPF in Brasilia. At 30 ng/mL, the highest larvae mortality rate was 2.7% for the population from Lago Norte, while that of pupae was 92.1% for Varjão and Vila Planalto. CONCLUSIONS: The five populations of Ae. aegypti from the FD are susceptible to PPF and there is a need to monitor the susceptibility of Ae. aegypti in new areas of the FD.


Assuntos
Aedes/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Piridinas/farmacologia , Animais , Brasil , Larva/efeitos dos fármacos
10.
PLoS Negl Trop Dis ; 14(2): e0008073, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32101555

RESUMO

The Aedes aegypti mosquito serves as a major vector for viral diseases, such as dengue, chikungunya, and Zika, which are spreading across the globe and threatening public health. In addition to increased vector transmission, the prevalence of insecticide-resistant mosquitoes is also on the rise, thus solidifying the need for new, safe and effective insecticides to control mosquito populations. We recently discovered that cinnamodial, a unique drimane sesquiterpene dialdehyde of the Malagasy medicinal plant Cinnamosma fragrans, exhibited significant larval and adult toxicity to Ae. aegypti and was more efficacious than DEET-the gold standard for insect repellents-at repelling adult female Ae. aegypti from blood feeding. In this study several semi-synthetic analogues of cinnamodial were prepared to probe the structure-activity relationship (SAR) for larvicidal, adulticidal and antifeedant activity against Ae. aegypti. Initial efforts were focused on modification of the dialdehyde functionality to produce more stable active analogues and to understand the importance of the 1,4-dialdehyde and the α,ß-unsaturated carbonyl in the observed bioactivity of cinnamodial against mosquitoes. This study represents the first investigation into the SAR of cinnamodial as an insecticide and antifeedant against the medically important Ae. aegypti mosquito.


Assuntos
Aedes/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Inseticidas/farmacologia , Sesquiterpenos Policíclicos/farmacologia , Animais , Feminino , Inseticidas/síntese química , Inseticidas/química , Larva/efeitos dos fármacos , Modelos Moleculares , Estrutura Molecular , Controle de Mosquitos , Sesquiterpenos Policíclicos/síntese química , Sesquiterpenos Policíclicos/química , Conformação Proteica , Canal de Cátion TRPA1/química , Canal de Cátion TRPA1/metabolismo
11.
Parasit Vectors ; 13(1): 19, 2020 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-31931883

RESUMO

BACKGROUND: Effective mosquito control approaches incorporate both adult and larval stages. For the latter, physical, biological, and chemical control have been used with varying results. Successful control of larvae has been demonstrated using larvicides including insect growth regulators, e.g. the organophosphate temephos, as well as various entomopathogenic microbial species. However, a variety of health and environmental issues are associated with some of these. Laboratory trials of essential oils (EO) have established the larvicidal activity of these substances, but there are currently no commercially available EO-based larvicides. Here we report on the development of a new approach to mosquito larval control using a novel, yeast-based delivery system for EO. METHODS: Food-grade orange oil (OO) was encapsulated into yeast cells following an established protocol. To prevent environmental contamination, a proprietary washing strategy was developed to remove excess EO that is adsorbed to the cell exterior during the encapsulation process. The OO-loaded yeast particles were then characterized for OO loading, and tested for efficacy against Aedes aegypti larvae. RESULTS: The composition of encapsulated OO extracted from the yeast microparticles was demonstrated not to differ from that of un-encapsulated EO when analyzed by high performance liquid chromatography. After lyophilization, the oil in the larvicide comprised 26-30 percentage weight (wt%), and is consistent with the 60-65% reduction in weight observed after the drying process. Quantitative bioassays carried with Liverpool and Rockefeller Ae. aegypti strains in three different laboratories presented LD50 of 5.1 (95% CI: 4.6-5.6) to 27.6 (95% CI: 26.4-28.8) mg/l, for L1 and L3/L4 mosquito larvae, respectively. LD90 ranged between 18.9 (95% CI: 16.4-21.7) mg/l (L1 larvae) to 76.7 (95% CI: 69.7-84.3) mg/l (L3/L4 larvae). CONCLUSIONS: The larvicide based on OO encapsulated in yeast was shown to be highly active (LD50 < 50 mg/l) against all larval stages of Ae. aegypti. These results demonstrate its potential for incorporation in an integrated approach to larval source management of Ae. aegypti. This novel approach can enable development of affordable control strategies that may have significant impact on global health.


Assuntos
Aedes/efeitos dos fármacos , Encapsulamento de Células/métodos , Controle de Mosquitos/métodos , Óleos Voláteis/farmacologia , Animais , Química Verde , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Óleos Vegetais/farmacologia , Saccharomyces cerevisiae
12.
Parasit Vectors ; 13(1): 11, 2020 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-31918753

RESUMO

BACKGROUND: Dengue fever outbreaks tend to spread northward in China, and Jining is the northernmost region where local dengue fever cases have been detected. Therefore, it is important to investigate the density of Aedes albopictus and its resistance to deltamethrin. METHODS: The Breteau index (BI) and container index (CI) were calculated to assess the larval density of Ae. albopictus and human-baited double net trap (HDN) surveillance was performed in six subordinate counties (Rencheng, Yanzhou, Sishui, Liangshan, Zoucheng and Jiaxiang) of Jining City in 2017 and 2018. The resistance of Ae. albopictus adults to deltamethrin was evaluated using the World Health Organization (WHO) standard resistance bioassay. The mutations at Vgsc codons 1532 and 1534 were also analysed to determine the association between kdr mutations and phenotypic resistance in adult mosquitoes. RESULTS: The average BI, CI and biting rate at Jining were 45.30, 16.02 and 1.97 (female /man/hour) in 2017 and 15.95, 7.86 and 0.59 f/m/h in 2018, respectively. In August 26, 2017, when the first dengue fever case was diagnosed, the BI at Qianli village in Jiaxiang County was 107.27. The application of prevention and control measures by the government sharply decreased the BI to a value of 4.95 in September 3, 2017. The mortality of field-collected Ae. albopictus females from Jiaxiang was 41.98%. I1532T, F1534L and F1534S mutations were found in domain III of the Vgsc gene. This study provides the first demonstration that both I1532T and F1534S mutations are positively correlated with the deltamethrin-resistant phenotype. CONCLUSIONS: Mosquito density surveillance, resistance monitoring and risk assessment should be strengthened in areas at risk for dengue to ensure the sustainable control of Ae. albopictus and thus the prevention and control of dengue transmission.


Assuntos
Aedes/efeitos dos fármacos , Dengue/transmissão , Resistência a Inseticidas , Inseticidas/farmacologia , Aedes/genética , Aedes/metabolismo , Aedes/virologia , Altitude , Animais , China , Dengue/virologia , Vírus da Dengue/genética , Vírus da Dengue/isolamento & purificação , Vírus da Dengue/fisiologia , Ecologia , Feminino , Humanos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Larva/efeitos dos fármacos , Larva/genética , Larva/metabolismo , Larva/virologia , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Mosquitos Vetores/metabolismo , Mosquitos Vetores/virologia , Mutação , Nitrilos , Piretrinas
13.
PLoS Negl Trop Dis ; 14(1): e0007970, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31961867

RESUMO

BACKGROUND: Arboviruses transmitted by day-biting Aedes mosquitoes are a major public health concern. With the challenges inherent in arbovirus vaccine and therapeutics development, vector control and bite prevention strategies are among the limited options available for immediate intervention. Bite prevention through personal protective technologies (PPT), such as topical mosquito repellents or repellent-impregnated clothing, may help to decrease biting rates and, therefore, the risk of disease in groups most susceptible to adverse outcomes from Zika virus. However, achieving high uptake and compliance with PPT can be challenging. METHODOLOGY/PRINCIPAL FINDINGS: To gain an insight into the knowledge and concerns of pregnant women surrounding Zika and their opinions regarding PPT, particularly repellent clothing, a focus group study was carried out with pregnant women, women of reproductive age, and semi-structured interviews with their male partners in two cities in Colombia. The discussions revealed shortfalls in basic knowledge of Zika virus, with several pregnant participants reporting being unaware of the potential for Zika-related congenital malformations. Although participants generally considered Zika to be a significant personal threat, most rated it as less of a concern than dengue or diarrheal diseases. Overall, repellent clothing and other forms of PPT were viewed as effective, although some participants expressed concerns over the high costs of repellents, and safety fears of regular contact with repellent chemicals, which they perceived as potentially harmful. Plant-derived repellents were considered to be safer than synthetic chemical repellents. Discussions also highlighted that health centers were the preferred source of information on bite-reduction. CONCLUSIONS/SIGNIFICANCE: Achieving high uptake and compliance with PPT in populations most at risk of adverse outcomes from Zika infection requires engaging key users in open dialogue to identify and address any practical issues regarding PPT use, and concerns over safety. The findings presented here suggest that educational campaigns should strongly emphasize the risks associated with Zika during pregnancy, and discuss safety profiles of approved synthetic repellents and the availability of EPA-approved plant-based repellents. In addition, the economic and political context should be a major consideration when evaluating personal mosquito-repellent strategies.


Assuntos
Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/psicologia , Zika virus/fisiologia , Adolescente , Adulto , Aedes/efeitos dos fármacos , Aedes/virologia , Animais , Colômbia , Estudos de Avaliação como Assunto , Feminino , Humanos , Repelentes de Insetos/farmacologia , Conhecimento , Masculino , Pessoa de Meia-Idade , Percepção , Equipamento de Proteção Individual/economia , Gravidez , Adulto Jovem , Infecção por Zika virus/economia , Infecção por Zika virus/virologia
14.
Chemosphere ; 247: 125795, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31927181

RESUMO

The association of low concentrations of pyriproxyfen and Spinosad, a naturally-occurring insecticide, was evaluated as an environment-friendly strategy to rationalize Aedes aegypti control programs by reducing larvicide consumption, saving financial costs and increasing residual effect against mosquitoes development. Firstly, the ecotoxicological parameters of the mixture was performed on non-target species Daphnia magna and the results confirmed that the low concentrations used in this larvicide mixture were not able to alter the reproductive parameters of chronically exposed microcrustaceans. In contrast, the mixture altered the behavior and development of Aedes aegypti, effectively inhibiting the emergence of adult insects for a long period. The results confirm the hypothesis that even at very low concentrations, the combination of the Spinosad and Pyriproxyfen larvicides offers an opportunity for Aedes aegypti public control programs to be more efficient.


Assuntos
Aedes/efeitos dos fármacos , Inseticidas/farmacologia , Macrolídeos/farmacologia , Controle de Mosquitos/métodos , Piridinas/farmacologia , Animais , Daphnia/efeitos dos fármacos , Combinação de Medicamentos , Ecotoxicologia/métodos , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento
15.
Artigo em Inglês | MEDLINE | ID: mdl-31678310

RESUMO

Insect growth regulators (IGRs) are attractive alternatives to chemical insecticides. Since it has been reported that secondary metabolites from actinomycetes show insecticidal activities against various insect pests, actinomycetes could be a potential source of novel IGR compounds. In the present study, insect juvenile hormone antagonists (JHANs) were identified from actinomycetes and their insect growth regulatory and insecticidal activities were investigated. A total of 363 actinomycetes were screened for their insect growth regulatory and insecticidal activities against Aedes albopictus and Plutella xylostella. Among them, Streptomyces sp. AN120537 showed the highest JHAN and insecticidal activities. Five antimycins were isolated as active compounds by assay-guided fractionation and showed high JHAN activities. These antimycins also exhibited significant insecticidal activities against A. albopictus, P. xylostella, F. occidentalis, and T. urticae. Moreover, dead larvae treated with these antimycins displayed morphological deformities that are similar to those of JH-based IGR-treated insects. This is the first report demonstrating that the insecticidal activities of antimycins resulted from their possible JHAN activity. Based on our results, it is expected that novel JHAN compounds potentially derived from actinomycetes could be efficiently applied as IGR insecticides with a broad insecticidal spectrum.


Assuntos
Actinobacteria/metabolismo , Aedes/efeitos dos fármacos , Inseticidas/isolamento & purificação , Inseticidas/farmacologia , Hormônios Juvenis/isolamento & purificação , Hormônios Juvenis/farmacologia , Lepidópteros/efeitos dos fármacos , Tetranychidae/efeitos dos fármacos , Animais , Inseticidas/química , Hormônios Juvenis/química , Metabolismo Secundário
16.
Ecotoxicol Environ Saf ; 189: 110050, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31816498

RESUMO

This study was aimed to investigate an effectual level of Annona muricata (soursop) extracts on mosquito vectors namely, Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. The toxicity study on non-target organism and other important biochemical marker enzymes to find and illustrate the exact mechanism of specific enzymes responsible for detoxifying allelochemicals. Among the various soursop seed kernel extracts tested for larvicidal activity, the 0.9% saline extract exhibited maximum mortality (100%) against three vectors at the lowest concentration for 24 h exposure. Based on these findings, the saline extract was opted for further studies including toxicity on non-target organism and systemic effects on important biochemical constituents in the larvae A. aegypti at the lethal threshold time (18 h) with LC50 concentration (0.009 mg/mL). The tested extract against non-target aquatic fourth instar larvae Chironomus costatus was safe up to 0.0028 mg/mL for 24 h exposure and the mortality was observed only above the concentration 0.0028 mg/mL used in the study. The systemic effects on main neuron transmitter Acetylcholinesterase (p ≤ 0.01), xenobiotics detoxifying enzyme of α-and ß-carboxylesterase (p ≤ 0.05; p ≤ 0.01) and antioxidant enzyme glutathione S-transferase (p ≤ 0.05) were reduced significantly in quantitative analysis. Analysis of such biochemical constituents of proteins and enzymes α-and ß-carboxylesterase were considerably down regulated in the resolving native-PAGE. In contrast, acid and alkaline phosphatase were upregulated in both quantitative and qualitative analysis. This investigation clearly demonstrates the soursop extract has potent larvicidal agent with alterations in biochemical constituents of exposed larvae of A. aegypti.


Assuntos
Aedes/efeitos dos fármacos , Annona/química , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Extratos Vegetais/farmacologia , Aedes/enzimologia , Animais , Anopheles/efeitos dos fármacos , Culex/efeitos dos fármacos , Inativação Metabólica , Larva/efeitos dos fármacos , Dose Letal Mediana
17.
J Ethnopharmacol ; 248: 112333, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31654797

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: The use of Hazomalania voyronii, popularly known as hazomalana, to repel mosquitoes and resist against insect attacks is handed down from generation to generation in Madagascar. In the present study, we investigated the ability of the essential oils (EOs) obtained from the stem wood, fresh and dry bark of H. voyronii to keep important mosquito vectors (Aedes aegypti and Culex quinquefasciatus) away, as well as their toxicity on three insect species of agricultural and public health importance (Cx. quinquefasciatus, Musca domestica and Spodoptera littoralis). MATERIALS AND METHODS: Hydrodistillation was used to obtain EOs from stem wood, fresh and dry bark. The chemical compositions were achieved by gas chromatography-mass spectrometry (GC-MS). Toxicity assays using stem wood and bark EOs were performed on larvae of Cx. quinquefasciatus and S. littoralis, and adults of M. domestica by WHO and topical application methods, respectively. Mosquito repellent activity of the most effective EO, i.e. the bark one, was determined on human volunteers by arm-in-cage tests, and results were compared with that of the commercial repellent N,N-ddiethyl-m-toluamide (DEET). RESULTS: The H. voyronii EOs were characterized by oxygenated monoterpenes with perilla aldehyde (30.9-47.9%) and 1,8-cineole (19.7-33.2%) as the main constituents. The fresh and dry bark EOs were the most active on Cx. quinquefasciatus and S. littoralis larvae, respectively, with LC50/LD50 of 65.5  mg L-1, and 50.5  µg larva-1; the EOs from wood and fresh bark displayed the highest toxicity on M. domestica (LD50 values 60.8 and 65.8 µg adult-1, respectively). Repellence assay revealed an almost complete protection (>80%) from both mosquito species for 30 min when pure fresh bark EO was applied on the volunteers' arm, while DEET 10% repelled >80% of the mosquitoes up to 120 min from application. CONCLUSION: The traditional use of the bark EO to repel insects has been demonstrated although an extended-release formulation based on H. voyronii EOs is needed to increase the repellent effect over time. A wide spectrum of insecticidal activity has been provided as well, suggesting a possible use of H. voyronii EOs in the fabrication of green repellents and insecticides useful to control mosquito vectors and agricultural pests.


Assuntos
Aedes/efeitos dos fármacos , Culex/efeitos dos fármacos , Hernandiaceae , Moscas Domésticas/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Controle de Mosquitos , Óleos Voláteis/farmacologia , Casca de Planta , Óleos Vegetais/farmacologia , Spodoptera/efeitos dos fármacos , Madeira , Aedes/crescimento & desenvolvimento , Animais , Culex/embriologia , DEET/farmacologia , Hernandiaceae/química , Moscas Domésticas/crescimento & desenvolvimento , Humanos , Repelentes de Insetos/isolamento & purificação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Óleos Voláteis/isolamento & purificação , Casca de Planta/química , Óleos Vegetais/isolamento & purificação , Spodoptera/embriologia , Fatores de Tempo , Madeira/química
18.
PLoS Negl Trop Dis ; 13(12): e0007852, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31830027

RESUMO

BACKGROUND: The yellow fever mosquito Aedes aegypti is the major vector of dengue, yellow fever, Zika, and Chikungunya viruses. Worldwide vector control is largely based on insecticide treatments but, unfortunately, vector control programs are facing operational challenges due to mosquitoes becoming resistant to commonly used insecticides. In Southeast Asia, resistance of Ae. aegypti to chemical insecticides has been documented in several countries but no data regarding insecticide resistance has been reported in Laos. To fill this gap, we assessed the insecticide resistance of 11 Ae. aegypti populations to larvicides and adulticides used in public health operations in the country. We also investigated the underlying molecular mechanisms associated with resistance, including target site mutations and detoxification enzymes putatively involved in metabolic resistance. METHODS AND RESULTS: Bioassays on adults and larvae collected in five provinces revealed various levels of resistance to organophosphates (malathion and temephos), organochlorine (DDT) and pyrethroids (permethrin and deltamethrin). Synergist bioassays showed a significant increased susceptibility of mosquitoes to insecticides after exposure to detoxification enzyme inhibitors. Biochemical assays confirmed these results by showing significant elevated activities of cytochrome P450 monooxygenases (P450), glutathione S-transferases (GST) and carboxylesterases (CCE) in adults. Two kdr mutations, V1016G and F1534C, were detected by qPCR at low and high frequency, respectively, in all populations tested. A significant negative association between the two kdr mutations was detected. No significant association between kdr mutations frequency (for both 1534C and 1016G) and survival rate to DDT or permethrin (P > 0.05) was detected. Gene Copy Number Variations (CNV) were detected for particular detoxification enzymes. At the population level, the presence of CNV affecting the carboxylesterase CCEAE3A and the two cytochrome P450 CYP6BB2 and CYP6P12 were significantly correlated to insecticide resistance. CONCLUSIONS: These results suggest that both kdr mutations and metabolic resistance mechanisms are present in Laos but their impact on phenotypic resistance may differ in proportion at the population or individual level. Molecular analyses suggest that CNV affecting CCEAE3A previously associated with temephos resistance is also associated with malathion resistance while CNV affecting CYP6BB2 and CYP6P12 are associated with pyrethroid and possibly DDT resistance. The presence of high levels of insecticide resistance in the main arbovirus vector in Laos is worrying and may have important implications for dengue vector control in the country.


Assuntos
Aedes/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Aedes/genética , Animais , Bioensaio , Sinergismo Farmacológico , Feminino , Dosagem de Genes , Genes de Insetos , Hidrocarbonetos Clorados/farmacologia , Laos , Larva/efeitos dos fármacos , Redes e Vias Metabólicas/genética , Mosquitos Vetores/genética , Mutação , Organofosfatos/farmacologia , Piretrinas/farmacologia
19.
Parasit Vectors ; 12(1): 603, 2019 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-31878970

RESUMO

BACKGROUND: Mutation of the voltage-gated sodium channel (VGSC) gene, or knockdown resistance (kdr) gene, is an important resistance mechanism against DDT and pyrethroids for dengue vector Aedes albopictus. A phenylalanine to serine (F1534S), leucine (F1534L) and cysteine (F1534C) substitution were detected in many Ae. albopictus populations around the world, and the mutant allele frequencies have been increasing in recent years. Therefore, it is essential to establish a simple, time-saving and cost-effective procedure to monitor the alleles in large-scale studies. METHODS: Based on the mutation genotypes of the 1534 locus in the kdr gene, F/F, F/S, F/C, F/L, S/S, C/C, L/L and S/C, we designed specific forward and reverse primers and optimized the reaction conditions for establishing of the allele-specific PCR(AS-PCR) detection technique. DNA sequencing in this study was taken as the gold standard, and used to determine the accuracy of AS-PCR. RESULTS: The designed AS-PCR technique showed high specificity for distinguishing the mutations at the 1534 locus, as the accuracy for F/F, F/S, F/C, F/L, S/S, C/C and S/C were 100%, 95.35%, 100%, 100%, 100%, 100% and 100%, respectively. CONCLUSIONS: The designed AS-PCR technique effectively distinguished individual genotypes for the mutations at the 1534 locus in the kdr gene, which could facilitate the knockdown resistance surveillance in Ae. albopictus in large-scale studies.


Assuntos
Aedes/genética , Dengue/transmissão , Proteínas de Insetos/genética , Resistência a Inseticidas , Inseticidas/farmacologia , Mosquitos Vetores/genética , Reação em Cadeia da Polimerase/métodos , Aedes/efeitos dos fármacos , Alelos , Animais , Humanos , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/metabolismo , Mutação
20.
Pestic Biochem Physiol ; 161: 5-11, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31685196

RESUMO

The adulticidal, larvicidal, and repellent activity of 18 trifluoromethylphenyl amides (TFMPAs) was determined against Aedes aegypti mosquitoes. The compounds studied are the third generation designed from active structures of the previous two generations. N-(3,5-Bis(trifluoromethyl)phenyl)-2-chloroacetamide (8f) and N-(3,5-bis(trifluoromethyl)phenyl)-2,2,3,3,3-pentafluoropropanamide (8h) were most active against 1st stage Ae. aegypti larvae with LC50 values of 125 and 2.53 µM; for comparative purposes, the published LC50 for fipronil is 0.014 µM. Compound 8h was the most toxic against adult female Ae. aegypti with an LD50 = 2.12 nmol/mg, followed by 8f, and N-(3,5-bis(trifluoromethyl)phenyl)-2,2,2-trifluoroacetamide (8g) with LD50 values of 4.27 and 4.73 nmol/mg, respectively, although these compounds were significantly less toxic than fipronil against adult female Ae. aegypti. Compounds N-(2-(trifluoromethyl)phenyl)butyramide (9c), N-(2-(trifluoromethyl)phenyl)pentanamide (9d) and N-(2-(trifluoromethyl)phenyl)hex-5-enamide (9e) were the best repellents for female Ae. aegypti, with minimum effective dosages (MEDs) of 0.026, 0.052, and 0.091 µmol/cm2, respectively, compared to DEET at 0.052 µmol/cm2. Out of 52 TFMPAs (total number of compounds from three generations of this research) compound 9c was the most active repellent along with two synthesized in our previous studies, 2-chloro-N-(3-(trifluoromethyl)phenyl)acetamide (6a) and 2,2,2-trifluoro-N-(2-(trifluoromethyl)phenyl)acetamide (4c).


Assuntos
Aedes/efeitos dos fármacos , Amidas/farmacologia , Repelentes de Insetos/farmacologia , Inseticidas/farmacologia , Aedes/embriologia , Animais , Bioensaio , Relação Dose-Resposta a Droga , Repelentes de Insetos/administração & dosagem , Repelentes de Insetos/química , Inseticidas/administração & dosagem , Inseticidas/química , Larva/efeitos dos fármacos , Relação Estrutura-Atividade
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