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1.
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
2.
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
3.
PLoS One ; 15(3): e0229764, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32130263

RESUMO

BACKGROUND: To investigate mosquito larval habitats and resistance to common insecticides in areas with high incidence rates of mosquito-borne diseases in Jining, Shandong Province, and to provide a scientific basis for the future prevention and control of mosquito-borne diseases and the rational use of insecticides. METHODS AND RESULTS: From June to September 2018, mosquito habitat characteristics and species compositions in Jintun town were studied through a cross-sectional survey. Larvae and pupae were collected in different habitats using the standard dipping technique. A total of 7,815 mosquitoes, comprising 7 species from 4 genera, were collected. Among them, Culex pipiens pallens (n = 5,336, 68.28%) was the local dominant species and found in all four habitats (rice paddies, irrigation channels, water containers, drainage ditches). There were 1,708 Cx. tritaeniorhynchus (21.85%), 399 Anopheles sinensis (5.11%), 213 Armigeres subalbatus (2.72%), 124 Aedes albopictus (1.59%), and 35 other (Cx. bitaeniorhynchus and Cx. halifaxii) (0.45%) mosquito samples collected. Spearman correlation analysis was employed to evaluate the relationship between larval density and the physicochemical characteristics of the breeding habitat. It was found that the larval density of Cx. tritaeniorhynchus correlated positively with water depth (r = 0.927 p = 0.003), the larval density of An. sinensis correlated positively with dissolved oxygen (DO) (r = 0.775 p = 0.041) and the larval density of Cx. p. pallens correlated positively with ammonia nitrogen (r = 0.527 p = 0.002). Resistance bioassays were carried out on the dominant populations of Cx. p. pallens: mosquitoes presented very high resistance to cypermethrin and deltamethrin, moderate resistance to dichlorvos (DDVP), and low resistance to Bacillus thuringiensis israelensis (Bti), with decreased susceptibility to propoxur. CONCLUSION: We showed that mosquito species vary across habitat type and that the mosquito larval density correlated positively with certain physicochemical characteristics in different habitats. In addition, Cx. p. pallens developed different levels of resistance to five insecticides. Vector monitoring should be strengthened after an epidemic, and further research should be conducted to scientifically prevent and kill mosquitoes.


Assuntos
Biomassa , Resistência a Inseticidas , Larva/fisiologia , Mosquitos Vetores/fisiologia , Animais , China , Clima , Inseticidas/toxicidade , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/crescimento & desenvolvimento
4.
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
5.
Parasitol Res ; 119(4): 1201-1208, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32036440

RESUMO

Knowledge of vector species composition and monitoring their change over time is critical to evaluate malaria transmission and assess control interventions. This is especially important in countries such as Botswana, where malaria transmission is subjected to fluctuations due to climate variability. Another important aspect that impacts vector populations is the insecticide resistance. In order to assess species composition and the presence of mutations associated with insecticide resistance, Anopheles specimens from larval samplings and indoor pyrethrum spray sheet collections were analysed. A total of 349 Anopheles were screened by morphology and PCR as belonging to the An. gambiae complex and An. funestus group. Specimens were subsequently analysed for human blood meal and Plasmodium index. Finally, knock-down resistance polymorphisms were assessed. Anopheles arabiensis accounted for the majority of specimens collected through larval (96.7%) and pyrethrum spray sheet collection (87.4%) across all sampling sites, and this species was the only one found positive for human blood and for P. falciparum. Other Anopheles species were collected in small numbers by pyrethrum spray catches, namely An. quadriannulatus, An. longipalpis type C and An. parensis. The authors speculate on changing climate patterns and their possible impact on species composition. The kdr assay revealed that Anopheles mosquitoes were homozygous wild type for both L1014F (kdr-w) and L1014S (kdr-e) mutations. These results highlight the unique vectorial role of An. arabiensis in Botswana and indicated that even with prolonged use of pyrethroids and DDT, the mosquito population has not developed kdr mutations, despite some in vivo evidence of insecticide resistance.


Assuntos
Anopheles/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Piretrinas/farmacologia , Animais , Botsuana , Feminino , Humanos , Resistência a Inseticidas/genética , Larva/efeitos dos fármacos , Malária/transmissão , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Mutação , Reação em Cadeia da Polimerase
6.
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
8.
Rev Soc Bras Med Trop ; 53: e20190211, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31994661

RESUMO

INTRODUCTION: Anopheles stephensi is the main malaria vector in Southeast Asia. Recently, plant-sourced larvicides are attracting great interests. METHODS: The essential oil was extracted from the leaf of Cinnamomum camphora (L.), and a bioassay was conducted to determine the larvicidal efficacy. The chemical composition of the essential oil was determined by GC-MS analysis. RESULTS: The oil showed strong, dose-dependent larvicidal activities. The onset of larvicidal efficiency was rapid. The LC50 and LC95 were determined as 0.146% and 1.057% at 1 h, 0.031% and 0.237% at 12 h, 0.026% and 0.128% at 24 h, respectively. The oil contains 32 compounds. CONCLUSIONS: The essential oil of C. camphora leaf has an excellent larvicidal potential for the control of A. stephensi.


Assuntos
Anopheles/efeitos dos fármacos , Cinnamomum camphora/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Óleos Voláteis/farmacologia , Animais , Anopheles/classificação , Bioensaio , Inseticidas/isolamento & purificação , Dose Letal Mediana , Mosquitos Vetores/classificação , Óleos Voláteis/isolamento & purificação
9.
Malar J ; 19(1): 9, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31906969

RESUMO

BACKGROUND: The complexity of mosquito-borne diseases poses a major challenge to global health efforts to mitigate their impact on people residing in sub-tropical and tropical regions, to travellers and deployed military personnel. To supplement drug- and vaccine-based disease control programmes, other strategies are urgently needed, including the direct control of disease vectors. Modern vector control research generally focuses on identifying novel active ingredients and/or innovative methods to reduce human-mosquito interactions. These efforts include the evaluation of spatial repellents, which are compounds capable of altering mosquito feeding behaviour without direct contact with the chemical source. METHODS: This project examined the impact of airborne transfluthrin from impregnated textile materials on two important malaria vectors, Anopheles dirus and Anopheles minimus. Repellency was measured by movement within taxis cages within a semi-field environment at the National Institute of Hygiene and Epidemiology in Hanoi, Vietnam. Knockdown and mortality were measured in adult mosquito bioassay cages. Metered-volume air samples were collected at a sub-set of points in the mosquito exposure trial. RESULTS: Significant differences in knockdown/mortality were observed along a gradient from the exposure source with higher rates of knockdown/mortality at 2 m and 4 m when compared with the furthest distance (16 m). Knockdown/mortality was also greater at floor level and 1.5 m when compared to 3 m above the floor. Repellency was not significantly different except when comparing 2 m and 16 m taxis cages. Importantly, the two species reacted differently to transfluthrin, with An. minimus being more susceptible to knockdown and mortality. The measured concentrations of airborne transfluthrin ranged from below the limit of detection to 1.32 ng/L, however there were a limited number of evaluable samples complicating interpretation of these results. CONCLUSIONS: This study, measuring repellency, knockdown and mortality in two malaria vectors in Vietnam demonstrates that both species are sensitive to airborne transfluthrin. The differences in magnitude of response between the two species requires further study before use in large-scale vector control programmes to delineate how spatial repellency would impact the development of insecticide resistance and the disruption of biting behaviour.


Assuntos
Anopheles/efeitos dos fármacos , Ciclopropanos/uso terapêutico , Fluorbenzenos/uso terapêutico , Repelentes de Insetos/uso terapêutico , Malária/prevenção & controle , Mosquitos Vetores/efeitos dos fármacos , Animais , Comportamento Alimentar/efeitos dos fármacos , Feminino , Humanos , Resistência a Inseticidas/efeitos dos fármacos , Malária/transmissão , Controle de Mosquitos/métodos , Vietnã
10.
Am J Trop Med Hyg ; 102(2s): 3-24, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31971144

RESUMO

In the context of stalling progress against malaria, resistance of mosquitoes to insecticides, and residual transmission, mass drug administration (MDA) of ivermectin, an endectocide used for neglected tropical diseases (NTDs), has emerged as a promising complementary vector control method. Ivermectin reduces the life span of Anopheles mosquitoes that feed on treated humans and/or livestock, potentially decreasing malaria parasite transmission when administered at the community level. Following the publication by WHO of the preferred product characteristics for endectocides as vector control tools, this roadmap provides a comprehensive view of processes needed to make ivermectin available as a vector control tool by 2024 with a completely novel mechanism of action. The roadmap covers various aspects, which include 1) the definition of optimal dosage/regimens for ivermectin MDA in both humans and livestock, 2) the risk of resistance to the drug and environmental impact, 3) ethical issues, 4) political and community engagement, 5) translation of evidence into policy, and 6) operational aspects of large-scale deployment of the drug, all in the context of a drug given as a prevention tool acting at the community level. The roadmap reflects the insights of a multidisciplinary group of global health experts who worked together to elucidate the path to inclusion of ivermectin in the toolbox against malaria, to address residual transmission, counteract insecticide resistance, and contribute to the end of this deadly disease.


Assuntos
Antiparasitários/farmacologia , Inseticidas/farmacologia , Ivermectina/farmacologia , Malária/prevenção & controle , Mosquitos Vetores/efeitos dos fármacos , África , Animais , Antiparasitários/uso terapêutico , Doenças Endêmicas/prevenção & controle , Humanos , Inseticidas/uso terapêutico , Ivermectina/uso terapêutico , Dose Letal Mediana , Malária/tratamento farmacológico , Malária/transmissão , Administração Massiva de Medicamentos , Segurança , Espanha , Organização Mundial da Saúde
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.
Parasitol Res ; 119(1): 55-62, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31786697

RESUMO

In developing countries, low-cost control and treatment programs that offer combined approaches against diseases and their vectors are certainly needed. Ivermectin (IVM) has been well known for its role in the treatment of parasitic diseases, due to its effect on glutamate-gated chloride channels. These same channels are also present in the mosquito vector, and thus, research has focused on the insecticidal effects of this drug. Possible alternative mechanisms of IVM on the physiology of mosquitoes, however, have not been sufficiently elaborated. We assessed the protease activity, lipid peroxidation, and local expression of STAT, p53, caspase-3, and Bax markers to study the effect of this antibiotic on digestion and immunity in Culex pipiens. Sugar- and blood-feeding assays were employed to investigate the potential influence of blood feeding on the dynamics of these parameters. IVM was found to have an effect on protease activity, lipid peroxidation as well as the expression of different markers investigated in this work. The focus on the detailed effect of this drug certainly opens the gate to broadening the spectrum of IVM and expanding its health and economic benefit, especially that it is relatively more affordable than other antibiotics on the market.


Assuntos
Canais de Cloreto/efeitos dos fármacos , Culex/efeitos dos fármacos , Inseticidas/farmacologia , Ivermectina/farmacologia , Animais , Caspase 3/biossíntese , Culex/imunologia , Culex/fisiologia , Digestão/efeitos dos fármacos , Imunidade/efeitos dos fármacos , Proteínas de Insetos/biossíntese , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/fisiologia , Fatores de Transcrição STAT/biossíntese , Proteína Supressora de Tumor p53/biossíntese , Proteína X Associada a bcl-2/biossíntese
14.
Proc Natl Acad Sci U S A ; 117(1): 708-716, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31871198

RESUMO

Mosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid's scent and the balance of excitation and inhibition in the mosquito's antennal lobe (AL). The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species-not visited by mosquitoes-emit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to N,N-diethyl-meta-toluamide (DEET), a mosquito repellent. Lateral inhibition between these 2 glomeruli reflects the level of attraction to the orchid scents. Whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door toward understanding the neural basis of mosquito nectar-seeking behaviors.


Assuntos
Aedes/fisiologia , Comportamento Apetitivo/fisiologia , Percepção Olfatória/fisiologia , Orchidaceae/fisiologia , Polinização/fisiologia , Animais , Comportamento Apetitivo/efeitos dos fármacos , Antenas de Artrópodes/citologia , Antenas de Artrópodes/fisiologia , Encéfalo/fisiologia , DEET/farmacologia , Feminino , Repelentes de Insetos/farmacologia , Masculino , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/fisiologia , Odorantes , Percepção Olfatória/efeitos dos fármacos , Neurônios Receptores Olfatórios/fisiologia , Polinização/efeitos dos fármacos
15.
Nature ; 577(7790): 376-380, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31875852

RESUMO

Pyrethroid-impregnated bed nets have driven considerable reductions in malaria-associated morbidity and mortality in Africa since the beginning of the century1. The intense selection pressure exerted by bed nets has precipitated widespread and escalating resistance to pyrethroids in African Anopheles populations, threatening to reverse the gains that been made by malaria control2. Here we show that expression of a sensory appendage protein (SAP2), which is enriched in the legs, confers pyrethroid resistance to Anopheles gambiae. Expression of SAP2 is increased in insecticide-resistant populations and is further induced after the mosquito comes into contact with pyrethroids. SAP2 silencing fully restores mortality of the mosquitoes, whereas SAP2 overexpression results in increased resistance, probably owing to high-affinity binding of SAP2 to pyrethroid insecticides. Mining of genome sequence data reveals a selective sweep near the SAP2 locus in the mosquito populations of three West African countries (Cameroon, Guinea and Burkina Faso) with the observed increase in haplotype-associated single-nucleotide polymorphisms mirroring the increasing resistance of mosquitoes to pyrethroids reported in Burkina Faso. Our study identifies a previously undescribed mechanism of insecticide resistance that is likely to be highly relevant to malaria control efforts.


Assuntos
Anopheles/metabolismo , Proteínas de Insetos/metabolismo , Resistência a Inseticidas , Inseticidas/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Piretrinas/farmacologia , África Central , Animais , Anopheles/genética , Feminino , Proteínas de Insetos/genética , Controle de Mosquitos
16.
Sci Total Environ ; 700: 134443, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31655455

RESUMO

Worldwide, billions of people are at risk from viruses, parasites and bacteria transmitted by mosquitoes, ticks, fleas and other vectors. Over exploitation of chemical pesticides to overcome the mosquito borne diseases led to detrimental effects on environment and human health. The present research aims to explore bio-fabrication of metal silver nanomaterials using Rhazya stricta extract against deadly mosquito vectors and microbial pathogens. The phytochemical profile of the R. stricta extracts was studied by HPLC-MS and 1H NMR. Further, confirmation of the bio-fabricated silver nanoparticles (AgNPs) was carried out by UV-vis spectroscopy and characterization through FTIR, TEM, EDX, and XRD analyses. The R. stricta-fabricated AgNPs showed acute toxicity on key mosquito vectors from two different country (India and Kingdom of Saudi Arabia, KSA) strains, notably, with LC50 values of 10.57, 11.89 and 12.78 µg/ml on malarial, dengue and filarial key Indian strains of mosquito vectors, respectively, and 30.66 and 38.39 µg/ml on KSA strains of Aedes aegypti and Culex pipiens, respectively. In mosquito adulticidal activity, R. stricta extract alone exhibited LC50 values ranging from 304.34 to 382.45 µg/ml against Indian strains and from 738.733 to 886.886 against Saudi Arabian strains, while AgNPs LC50 boosted from 9.52 to 12.16 µg/ml and from 30.66 to 38.39 µg/ml, respectively. Moreover, it was noticed that at low concentration the tested AgNPs showed high growth retardation of important pathogenic bacteria such as Bacillus subtilis, Klebsiella pneumoniae and Salmonella typhi with inhibition zone diameters from 11.86 to 22.92 mm. In conclusion, the present study highlighted that R. stricta-fabricated AgNPs could be a lead material for the management of mosquito vector and microbial pathogens control.


Assuntos
Anti-Infecciosos/química , Apocynaceae , Inseticidas/química , Nanopartículas Metálicas/química , Mosquitos Vetores/efeitos dos fármacos , Extratos Vegetais/química , Prata/química , Anti-Infecciosos/toxicidade , Índia , Inseticidas/toxicidade , Dose Letal Mediana , Controle de Mosquitos/métodos , Extratos Vegetais/toxicidade
17.
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
18.
Proc Natl Acad Sci U S A ; 116(51): 25764-25772, 2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31801878

RESUMO

Resistance in Anopheles gambiae to members of all 4 major classes (pyrethroids, carbamates, organochlorines, and organophosphates) of public health insecticides limits effective control of malaria transmission in Africa. Increase in expression of detoxifying enzymes has been associated with insecticide resistance, but their direct functional validation in An. gambiae is still lacking. Here, we perform transgenic analysis using the GAL4/UAS system to examine insecticide resistance phenotypes conferred by increased expression of the 3 genes-Cyp6m2, Cyp6p3, and Gste2-most often found up-regulated in resistant An. gambiae We report evidence in An. gambiae that organophosphate and organochlorine resistance is conferred by overexpression of GSTE2 in a broad tissue profile. Pyrethroid and carbamate resistance is bestowed by similar Cyp6p3 overexpression, and Cyp6m2 confers only pyrethroid resistance when overexpressed in the same tissues. Conversely, such Cyp6m2 overexpression increases susceptibility to the organophosphate malathion, presumably due to conversion to the more toxic metabolite, malaoxon. No resistant phenotypes are conferred when either Cyp6 gene overexpression is restricted to the midgut or oenocytes, indicating that neither tissue is involved in insecticide resistance mediated by the candidate P450s examined. Validation of genes conferring resistance provides markers to guide control strategies, and the observed negative cross-resistance due to Cyp6m2 gives credence to proposed dual-insecticide strategies to overcome pyrethroid resistance. These transgenic An. gambiae-resistant lines are being used to test the "resistance-breaking" efficacy of active compounds early in their development.


Assuntos
Anopheles , Genes de Insetos/genética , Genômica/métodos , Resistência a Inseticidas/genética , Mosquitos Vetores , Animais , Animais Geneticamente Modificados , Anopheles/efeitos dos fármacos , Anopheles/genética , Sistema Enzimático do Citocromo P-450/genética , Feminino , Glutationa Transferase/genética , Inseticidas/farmacologia , Malária/prevenção & controle , Malária/transmissão , Masculino , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Fenótipo
19.
Infect Dis Poverty ; 8(1): 100, 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31796068

RESUMO

BACKGROUND: The Sahel region of Chad Republic is a prime candidate for malaria pre-elimination. To facilitate pre-elimination efforts in this region, two populations of Anopheles coluzzii from Central Chad Republic were characterized, their insecticide resistance profile and the possible molecular mechanisms driving the resistance in the field investigated. METHODS: Bloodfed female Anopheles gambiae s.l. resting indoor, were collected at N'djamena and Massakory, Chad in 2018 and characterized for species composition, and infection rate was determined using the TaqMan assay. Susceptibility to various insecticides was assessed using WHO tube bioassays. Cone bioassays were conducted using various long-lasting insecticidal nets (LLINs). Results were analysed using Chi Square test. Knockdown resistance (kdr) and ace-1 markers were investigated by TaqMan genotyping. RESULTS: Anopheles coluzzii was the major vector found in N'djamena (100%) and Massakory (~ 94%). No Plasmodium was found in 147 bloodfed F0 An. coluzzii (82 from N'djamena and 65 from Massakory). High intensity pyrethroid resistance was observed with mortalities of < 2% for permethrin, deltamethrin and etofenprox, and with < 50% and < 60% dead following exposure to 10× diagnostic doses of deltamethrin and permethrin, respectively. For both sites, < 10% mortalities were observed with DDT. Synergist bioassays with piperonylbutoxide significantly recovered pyrethroid susceptibility in Massakory populations, implicating CYP450s (mortality = 13.6% for permethrin, χ2 = 22.8, df = 1, P = 0.0006; mortality = 13.0% for deltamethrin, χ2 = 8.8, df = 1, P < 0.00031). Cone-bioassays established complete loss of efficacy of the pyrethroid-based LLINs; and a 100% recovery of susceptibility following exposure to the roof of PermaNet®3.0, containing piperonylbutoxide. Both populations were susceptible to malathion, but high bendiocarb resistance was observed in Massakory population. The absence of ace-1 mutation points to the role of metabolic resistance in the bendiocarb resistance. Both 1014F and 1014S mutations were found in both populations at around 60% and < 20% respectively. Sequencing of intron-1 of the voltage-gated sodium channel revealed a low genetic diversity suggesting reduced polymorphism. CONCLUSIONS: Multiple resistance in An. coluzzii populations from Chad highlight challenges associated with deployment of LLINs and indoor residual spraying (IRS) in the Sahel of this country. The pyrethroid-synergists LLINs (e.g. PermaNet®3.0) and organophosphate-based IRS maybe the alternatives for malaria control in this region.


Assuntos
Anopheles/fisiologia , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Malária/transmissão , Mosquitos Vetores/fisiologia , Animais , Anopheles/efeitos dos fármacos , Anopheles/genética , Chade , Feminino , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética
20.
Parasit Vectors ; 12(1): 591, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31852489

RESUMO

Culex quinquefasciatus is a successful invasive species broadly distributed in subtropical regions, including Brazil. It is an extremely annoying mosquito due to its nocturnal biting behavior, in high-density populations and it is a potential bridge between sylvatic arbovirus from birds to man in urban territories. Herein, we present a review concerning the methods of chemical control employed against Cx. quinquefasciatus in Brazil since the 1950's and insecticide resistance data registered in the literature. As there is no specific national programme for Cx. quinquefasciatus control in Brazil, the selection of insecticide resistance is likely due in part to the well-designed chemical campaigns against Aedes aegypti and the elevated employment of insecticides by households and private companies. There are very few publications about insecticide resistance in Cx. quinquefasciatus from Brazil when compared to Ae. aegypti. Nevertheless, resistance to organophosphates, carbamate, DDT, pyrethroids and biolarvicides has been registered in Cx. quinquefasciatus populations from distinct localities of the country. Concerning physiological mechanisms selected for resistance, distinct patterns of esterases, as well as mutations in the acetylcholinesterase (ace-1) and voltage-gated sodium channel (NaV) genes, have been identified in natural populations. Given environmental changes and socioeconomical issues in the cities, in recent years we have been experiencing an increase in the number of disease cases caused by arboviruses, which may involve Cx. quinquefasciatus participation as a key vector. It is urgent to better understand the efficiency and susceptibility status to insecticides, as well as the genetic background of known resistant mechanisms already present in Cx. quinquefasciatus populations for an effective and rapid chemical control when eventually required.


Assuntos
Culex/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Animais , Brasil , Culex/enzimologia , Culex/genética , Humanos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/enzimologia , Mosquitos Vetores/genética
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