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1.
J Am Mosq Control Assoc ; 36(1): 22-32, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32497474

RESUMO

In several insect species, resistance to pyrethroids and DDT (dichlorodiphenyltrichloroethane) is linked to point mutations in the voltage-gated sodium channel (VGSC) gene. Pyrethroid-based insecticides prolong the opening of sodium channels, causing paralysis known as a "knockdown" effect before mortality occurs. Point mutations in the VGSC gene result in decreased pyrethroid binding and reduced sensitivity to the insecticide-this resistance mechanism is known as knockdown resistance (kdr) as insects do not die but recover from paralysis with time. In Culex mosquito species loss of target site sensitivity to pyrethroids is linked to a number of substitutions, one of which is leucine (L) to phenylalanine (F) at residue 1014 (L1014F) in the VGSC gene. Here we report the identification of kdr-associated pyrethroid resistance and developing resistance in Cx. quinquefasciatus field collections from Collier County, FL. Evaluation of position 1014 of the VGSC in Cx. quinquefasciatus collections from 7 locations in Collier County, FL, revealed a wide range of genotypes from one part of the district to the other. Centers for Disease Control and Prevention bottle bioassay, linear regression analysis, and cage trial evaluations suggest that the L1014F mutation plays a role, at least in part, to the pyrethroid resistance status of Cx. quinquefasciatus collected in Collier County, FL. Furthermore, we identified resistance attributed to both oxidase and esterase activity, indicating that multiple mechanisms are responsible for pyrethroid resistance in Collier County Cx. quinquefasciatus.


Assuntos
Culex/genética , Esterases/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Oxirredutases/genética , Piretrinas/farmacologia , Animais , Culex/efeitos dos fármacos , Culex/enzimologia , Esterases/metabolismo , Feminino , Florida , Oxirredutases/metabolismo
2.
Folia Parasitol (Praha) ; 672020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32350159

RESUMO

We observed instances of cannibalism (intraspecific predation) among intra-instar larvae of Culex pipiens Linnaeus, 1758 while performing a bioassay of Lysinibacillus sphaericus (formerly named Bacillus sphaericus) larvicide, when the larvae were exposed to the larvicide for 48 h in the absence of food. Larvae without symptoms of poisoning attacked and devoured those visibly affected. Cannibalism was more prevalent in 1st-2nd instar larvae than in 3rd-4th instar. This phenomenon should be taken into account when interpreting the results of larvicide bioassays, especially when the exposure lasts over 24 h. The necessity of creating optimal conditions for organisms tested is emphasised.


Assuntos
Bacillaceae/química , Culex/efeitos dos fármacos , Inseticidas/administração & dosagem , Fatores Etários , Animais , Canibalismo , Culex/crescimento & desenvolvimento , Culex/fisiologia , Inseticidas/química , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/fisiologia
3.
PLoS One ; 15(5): e0226859, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32437348

RESUMO

INTRODUCTION: Larvicide application in ovitrap is one of the currently available methods used in mosquito eradication campaign. We previously reported that copper in liquid form is a promising candidate due to its potent larvicide properties in a laboratory setting and in the field. In the field study, several larvae survived in outdoor ovitrap due to the dilution of copper concentration by rainwater. The surviving larvae were smaller and less motile. This led our interest to study the effect of a sub-lethal dose of copper in ovitrap on mosquito larval development, pupation time and lifespan in the adult stage. METHODS: First instar larvae of Aedes albopictus, Anopheles stephensi, and Culex pipiens were put in water containing 0.15 ppm, 0.30 ppm, and 0.60 ppm of copper. The surviving larvae, the emerging pupae, and adult mosquitoes were observed and counted every 24-hour and statistically analyzed by t-test or Mann-Whitney U test. Inter-species difference in response to different concentration of copper were also analyzed. RESULTS: Copper showed a potent larvicide effect at 0.60 ppm concentration. Prolonged pupation time and a lower number of adult mosquitoes were observed at 0.15 ppm concentration. Copper exposure did not affect adult mosquitoes' lifespan. Culex pipiens was the most susceptible species to copper exposure. CONCLUSION: This study demonstrates the efficacy of copper at <1 ppm to kill mosquito larvae and to prolong pupation and adult emergence time. Utilization of copper at a low concentration is cost-efficient in the public health setting and remains an open option as an environmentally safe vector control strategy.


Assuntos
Cobre/farmacologia , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Aedes/efeitos dos fármacos , Animais , Anopheles/efeitos dos fármacos , Culex/efeitos dos fármacos
4.
PLoS Negl Trop Dis ; 14(5): e0008284, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32357192

RESUMO

BACKGROUND: Diflubenzuron (DFB) is one of the most used insecticides in mosquito larval control including that of Culex pipiens, the proven vector of the recent West Nile Virus epidemics in Europe. Two mutations (I1043L and I1043M) in the chitin synthase (CHS) putative binding site of DFB have been previously reported in Cx. pipiens from Italy and associated with high levels of resistance against this larvicide. METHODOLOGY/PRINCIPAL FINDINGS: Here we report the identification of a third mutation at the same I1043 position of the CHS gene resulting in the substitution of Isoleucine to Phenylalanine (I1043F). This mutation has also been found in agricultural pests and has been functionally validated with genome editing in Drosophila, showing to confer striking levels (>15,000 fold) of DFB resistance. The frequency of the I1043F mutation was found to be substantially higher in Cx. pipiens mosquitoes surviving DFB doses largely exceeding the recommended field dose, raising concerns about the future efficient use of this insecticide. We monitored the presence and frequency of DFB mutations in Cx. pipiens mosquitoes from several Mediterranean countries, including Italy, France, Greece, Portugal and Israel. Among the Cx. pipiens populations collected in Northern Italy all but one had at least one of the three DFB mutations at allele frequencies reaching 93.3% for the I1043M, 64.8% for the I1043L and 10% for the I1043F. The newly reported I1043F mutation was also identified in two heterozygote individuals from France (4.2% allelic frequency). In contrast to Italy and France, no DFB resistant mutations were identified in the Cx. pipiens mosquitoes sampled from Greece, Portugal and Israel. CONCLUSIONS/SIGNIFICANCE: The findings of our study are of major concern for mosquito control programs in Europe, that rely on the use of a limited number of available larvicides, and highlight the necessity for the development of appropriate Insecticide Resistance Management (IRM) programs, to ensure the sustainable use of DFB.


Assuntos
Quitina Sintase/genética , Culex/enzimologia , Diflubenzuron/farmacologia , Proteínas de Insetos/genética , Resistência a Inseticidas , Inseticidas/farmacologia , Mutação Puntual , Animais , Culex/efeitos dos fármacos , Culex/genética , Região do Mediterrâneo , Mutação de Sentido Incorreto
5.
PLoS One ; 15(5): e0232172, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32365106

RESUMO

BACKGROUND: The fungal toxin acts as effective, low-cost chemical substances for pest control worldwide and also an alternative to synthetic insecticides. This study assessed the larvicidal potential of Metarhizium anisopliae fungi derived metabolites against Aedes aegypti, Anopheles stephensi, Culex quinquefasciatus and non-targeted organisms at 24hr post treatment. METHOD: Isolation of entomopathogenic fungi M. anisopliae from natural traps confirmed by using 18s rDNA biotechnological tools. Crude extracts from M. anisopliae solvent extraction and their secondary metabolites were bio-assayed following WHO standard procedures against Ae. aegypti, An. stephensi and Cx. quinquefasciatus, Artemia nauplii, Eudrilus eugeniae, and Solanum lycopersicum after 24 hr exposure. Histopathological analysis of E. eugeniae treated with fungi metabolites toxicity compared to those treated with Monocrotophos after 24hrpost-treatment. M. anisopliae metabolites were characterized using GC-MS and FT-IR analysis. RESULTS: The larvicidal activity was recorded in highest concentration of 75µg/ml, with 85%, 97% and 89% mortality in Ae. aegypti, An. stephensi and Cx. quinquefasciatus respectively. M. anisopliae metabolites produced LC50 values in Ae. aegypti, 59.83µg/ml, in An. stephensi, 50.16µg/ml and in Cx. quinquefasciatus, 51.15µg/ml respectively. M. anisopliae metabolites produced lower toxic effects on A. nauplii, LC50 values were, 54.96µg/ml respectively. Bio-indicator toxicity results show 18% and 58% mortality was recorded in E. eugeniae and A. nauplii and also there is no phytotoxicity that was observed on S. lycopersicum L. under semi-field condition. E. eugeniae histopathological studies shows fungal metabolites showed lower sub-lethal effects compared to synthetic chemical pesticide at 24hrs of the treatment. The GC-MS and FT-IR analysis identified five major components of active ingredients. CONCLUSION: Findings of this study indicate that, M. anisopliae ethyl acetate derived secondary metabolites are effective against larvae of Ae. aegypti, An. stephensi and Cx. quinquefasciatus mosquito species, lower toxicity effects were observed on non-target organisms such as, Artemia nauplii, Eudrilus eugeniae as well as, no toxicity effect were observed on Solanum lycopersicum. Further research should be conducted in laboratory for separation of single pure molecule and be tested semifield conditions.


Assuntos
Aedes/efeitos dos fármacos , Anopheles/efeitos dos fármacos , Produtos Biológicos/farmacologia , Culex/efeitos dos fármacos , Metarhizium/química , Animais , Produtos Biológicos/química , DNA Fúngico/genética , DNA Ribossômico/genética , Cromatografia Gasosa-Espectrometria de Massas , Controle de Insetos , Larva/efeitos dos fármacos , Metarhizium/genética , Metarhizium/isolamento & purificação , Monocrotofós/farmacologia , RNA Ribossômico 18S/genética , Metabolismo Secundário , Espectroscopia de Infravermelho com Transformada de Fourier
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.
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
8.
J Oleo Sci ; 69(2): 153-160, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32023580

RESUMO

The chemical composition and larvicidal activity of essential oils from the leaves and rhizomes of Zingiber collinsii Mood & Theilade (Zingiberaceae) were reported. The main compounds in the leaf oil were α-pinene (25.6%), ß-caryophyllene (16.8%), ß-pinene (16.1%) and bicyclogermacrene (6.9%) while the rhizome oil consist mainly of camphene (22.5%), ß-pinene (16.3%), α-pinene (9.0%) and humulene oxide II (9.0%). The rhizome oil demonstrated larvicidal effects towards fourth instant larvae of mosquito vectors. The highest mortality (100%) was observed at 24 h exposure against Aedes albopictus (concentration 100 µg/mL) and 48 h (concentration of 50 and 100 µg/mL), while the highest mortality (100%) was observed for Culex quinquefasciatus at 24 h and 48 h at concentration of 100 µg/mL. The 24 h mosquito larvicidal activity of the rhizome oil against Ae. albopictus were LC50 = 25.51 µg/mL; LC90 = 40.22 µg/mL and towards Cx. quinquefasciatus with LC50 = 50.11 µg/mL and LC90 = 71.53 µg/mL). However, the 48 h larvicidal activity were LC50 = 20.03 µg/mL and LC90 = 24.51 µg/mL (Ae. albopictus), as well as LC50 = 36.18 µg/mL and LC90 = 55.11 µg/mL (Cx. quinquefasciatus). On the other hand, no appreciable mortality and larvicidal activity was observed for the leaf oil. The larvicidal activity of the essential oils of Z. collinsii was being reported for the first time.


Assuntos
Aedes/efeitos dos fármacos , Culex/efeitos dos fármacos , Larva/efeitos dos fármacos , Óleos Voláteis/farmacologia , Zingiberaceae/química , Animais
9.
Chem Biodivers ; 17(2): e1900580, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31913571

RESUMO

Developing effective and eco-friendly antimicrobials and pesticides has become a highly important issue. The repellent, insecticidal and antimicrobial activity of essential oils (EOs) isolated by hydrodistillation from dried leaves of the three Eucalyptus species (E. cloeziana, E. umbellata and E. benthamii) were investigated. During GC/MS analysis, α-pinene (47.36 %), 1,8-cineol (38.53 %) and α-pinene (35.31 %) were identified as major components of E. cloeziana, E. umbellata and E. benthamii, respectively. The EOs from E. cloeziana exhibited the longest effective protection time (465 min, at 50.0 % w/w) for humans among the EOs studied. The effective protection time was 30 min and 300 min at concentrations of 12.5 % (w/w) and 25.0 % (w/w), respectively. Fumigating insecticidal activity of EOs from three Eucalyptus species was tested by airtight fumigation in conical flask, which indicated that essential oils had a highly and rapidly insecticidal activity on Culex pipiens quinquefasciatus. The antimicrobial activity of EOs was evaluated by using disc diffusion and agar dilution methods. There was no significant difference in the antibacterial activity of EOs from E. cloeziana and E. umbellate and they had the same MICs (20 mL/L) on Staphylococcus aureus, Salmonella typhi, Bacillus subtilis and Escherichia coli. E. benthamii had the worst microbial inhibitory effect among the three Eucalyptus essential oils and the MIC value for the test species is 40 mL/L except for Rhodotorula Harrison (10 mL/L).


Assuntos
Anti-Infecciosos/química , Eucalyptus/química , Repelentes de Insetos/química , Inseticidas/química , Óleos Voláteis/química , Folhas de Planta/metabolismo , Animais , Anti-Infecciosos/farmacologia , Aspergillus/efeitos dos fármacos , Candida/efeitos dos fármacos , Culex/efeitos dos fármacos , Eucalyptus/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Testes de Sensibilidade Microbiana , Óleos Voláteis/análise , Óleos Voláteis/farmacologia , Folhas de Planta/química
10.
Parasitol Res ; 119(1): 23-30, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31760499

RESUMO

The wide application of pyrethroids has led to the rapid development of insecticide resistance in mosquitoes, leading to a rise in mosquito-borne diseases. We previously identified five differentially expressed lipase family genes upon evaluating the transcriptomes of deltamethrin-resistant and deltamethrin-susceptible strains of Culex pipiens pallens. Herein, the gene expression levels were verified by quantitative real-time PCR, and two lipase family genes, lipase A and pancreatic triacylglycerol lipase A, were chosen for further investigations. Using cell viability assays and Centers for Disease Control and Prevention bottle bioassays, lipase A was found to increase the resistance of mosquitoes against deltamethrin both in vitro and in vivo. Our findings indicate that lipase A is involved in conferring deltamethrin resistance in Cx. pipiens pallens.


Assuntos
Culex/efeitos dos fármacos , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Lipase/genética , Nitrilos/farmacologia , Piretrinas/farmacologia , Animais , Culex/enzimologia , Culex/genética , Proteínas de Insetos/genética , Reação em Cadeia da Polimerase em Tempo Real , Transcriptoma
11.
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
12.
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
13.
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
14.
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
15.
Mar Drugs ; 17(12)2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31756930

RESUMO

Four new xanthene derivatives, penicixanthenes A-D (1-4), and one known compound 5 were isolated from a marine mangrove endophytic fungus Penicillium sp. JY246 that was obtained from the stem of Ceriops tagal. Their structures were determined by detailed NMR, MS spectroscopic data, modified Mosher's method, and calculated electronic circular dichroism data. All of the isolated compounds were examined for insecticidal activity. Compounds 2 and 3 showed growth inhibition activity against newly hatched larvae of Helicoverpa armigera Hubner with the IC50 values 100 and 200 µg/mL, respectively, and compounds 1, 3, and 4 showed insecticidal activity against newly hatched larvae of Culex quinquefasciatus with LC50 values of 38.5 (±1.16), 11.6 (±0.58), and 20.5 (±1) µg/mL, respectively. The four xanthene derivatives have the potential to be developed as new biopesticides.


Assuntos
Agentes de Controle Biológico/toxicidade , Endófitos/metabolismo , Penicillium/metabolismo , Xantenos/toxicidade , Animais , Agentes de Controle Biológico/isolamento & purificação , Agentes de Controle Biológico/metabolismo , Culex/efeitos dos fármacos , Concentração Inibidora 50 , Larva , Mariposas/efeitos dos fármacos , Rhizophoraceae/microbiologia , Áreas Alagadas , Xantenos/isolamento & purificação , Xantenos/metabolismo
16.
J Photochem Photobiol B ; 200: 111650, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31698288

RESUMO

The biosynthesis of ZnO nanoparticles was synthesized by biogenic reduction of applied Cucurbita seed extract. The powder X-ray diffraction pattern displayed the high crystalline nature of synthesized ZnO nanoparticles and the crystallite size was calculated at 35 nm range. The Fourier Transform Infra-Red study revealed the functional groups of biogenic reduction and vibrational bands present in the synthesized nanoparticles. The UV-Visible analysis explained the SPR absorption peak at 371 nm. The Photoluminescence study revealed the strong red shoulder emission peak at 665 nm. The particle size analyzer displayed the particle size occupies majorly on 45-65 nm. The SEM analysis pointed the ZnO nanoparticles under rod, rectangular and hexagonal shapes were procured. The EDAX spectrum also mapping exposed the purity of formed ZnO nanoparticles with just Zn and O peaks. The HRTEM analysis exposed the hexagonal shape wurtzite structure ZnO particles formation. The physiochemical analysis revealed general nature of Cucurbita seed powder moreover which explained the phytochemicals involved in biogenic reduction of ZnO nanoparticles. The formed ZnO nanoparticles exhibited good antibacterial activity on E. coli, Bacillus pumilus, and Salmonella typhi bacteria. The cytotoxicity study stated the good toxicity on E. coli AB 1157. The antifungal activity showed a better effect on Aspergillus flavus and Aspergillus niger fungi. The antioxidant activity clarified the good free radical scavenging action. The anti larvicidal activity expressed a better impact on Culex tritaeniorhynchus mosquito larvae.


Assuntos
Cucurbita/química , Culex/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Extratos Vegetais/química , Óxido de Zinco/química , Animais , Antibacterianos/biossíntese , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/química , Antifúngicos/metabolismo , Antifúngicos/farmacologia , Aspergillus niger/efeitos dos fármacos , Cucurbita/metabolismo , Culex/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Química Verde , Larva/efeitos dos fármacos , Nanopartículas Metálicas/química , Tamanho da Partícula , Sementes/química , Sementes/metabolismo
17.
PLoS One ; 14(11): e0224810, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31689339

RESUMO

Insect repellents are widely used as the first line of defense against mosquito bites and transmission of disease-causing agents. However, the cost of daily applications of even the most affordable and the gold standard of insect repellents, DEET, is still high for low-income populations where repellents are needed the most. An Indian clove-based homemade recipe has been presented as a panacea. We analyzed this homemade repellent and confirmed by behavioral measurements and odorant receptor responses that eugenol is the active ingredient in this formulation. Prepared as advertised, this homemade repellent is ineffective, whereas 5x more concentrated extracts from the brand most enriched in eugenol showed moderate repellency activity against Culex quinquefasciatus and Aedes aegypti. DEET showed higher performance when compared to the 5x concentrated formulation and is available in the same market at a lower price than the cost of the ingredients to prepare the homemade formulation.


Assuntos
Aedes/efeitos dos fármacos , Culex/efeitos dos fármacos , DEET/toxicidade , Repelentes de Insetos/toxicidade , Syzygium/química , Animais , DEET/química , Etanol , Eugenol/toxicidade , Repelentes de Insetos/química , Oócitos/efeitos dos fármacos , Oócitos/metabolismo , Extratos Vegetais/toxicidade , Receptores Odorantes/metabolismo , Fatores de Tempo
18.
Aquat Toxicol ; 216: 105310, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31580997

RESUMO

Pesticide mixtures are increasingly used to fight pest species that developed resistance to pesticides. To assess the pesticide control efficiency and to reduce ecological damage to non-target species, it is important to quantify the effect of these mixtures and compare them with the effect of their single pesticides on pest species, non-target species and their predator-prey interactions. We studied the effects of the chemical pesticide chlorpyrifos (CPF), the biopesticide Bacillus thuringiensis israelensis (Bti) and their mixture both on the direct mortality and on the mortality by predation. We focused on larvae of a CPF-resistant and a non-resistant strain of the vector mosquito Culex quinquefasciatus and its predator, the pygmy backswimmer Plea minutissima. In the CPF-Bti mixture, both pesticides interacted antagonistically for direct mortality. Exposure to the mixture caused equal direct mortality and equal mortality by predation in both strains. As expected, exposure to CPF resulted in less direct mortality and less mortality by predation in the CPF-resistant mosquito strain compared to the non-resistant strain. Notably, Bti caused a higher mortality in the mosquito larvae of the CPF-resistant strain compared to the non-resistant strain. Furthermore, the predator killed more mosquito larvae of the resistant strain compared to the non-resistant strain when exposed before to Bti alone. These observations identify a novel cost of resistance to a chemical pesticide in terms of increased vulnerability to a biopesticide.


Assuntos
Agentes de Controle Biológico/toxicidade , Praguicidas/toxicidade , Comportamento Predatório/efeitos dos fármacos , Animais , Bacillus thuringiensis/efeitos dos fármacos , Clorpirifos/toxicidade , Culex/efeitos dos fármacos , Reação de Congelamento Cataléptica/efeitos dos fármacos , Heterópteros/efeitos dos fármacos , Larva/efeitos dos fármacos , Modelos Lineares , Natação , Poluentes Químicos da Água/toxicidade
19.
Mater Sci Eng C Mater Biol Appl ; 104: 109984, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500006

RESUMO

The present investigation highlights the strong antioxidant, anticancer and larvicidal potential of green synthesized silver nanoparticles (AgNPs) using aqueous leaf extract of Piper longum L. for their diverse therapeutic applications. The optimum conditions for the synthesis of AgNPs were recorded as 1 mM AgNO3, 60 ±â€¯2 °C at pH 6 for 120 min. Synthesized AgNPs proved to be highly stable and monodispersed as characterized through various techniques. UV-Vis spectrum of biosynthesized AgNPs showed a maximum absorption peak at 420 nm. Field emission-Scanning electron microscopy (FE-SEM) and High resolution-Transmission electron microscopy (HR-TEM) micrographs showed the spherical shape of AgNPs with mean diameter size of 28.8 nm. Existence of crystallographic AgNPs was proved by X-ray diffraction (XRD) pattern analysis. Presence of phenolics, terpenoids and flavonoids compounds which act as bioreducing agents were confirmed by Fourier-transform infrared spectroscopy (FTIR) analysis. Furthermore, the AgNPs and leaf extracts prepared individually in different solvents such as methanol, ethyl acetate, chloroform, hexane and aqueous were assessed for their bio-efficacies. AgNPs showed the enhanced antioxidant (IC50 67.56 µg) and radical-scavenging activities (IC50 196.8 µg) as compared to the crude leaf extracts. Anticancer activity revealed the strong and dose-dependent cytotoxic effect of AgNPs against the HeLa cells showing maximum IC50 value being 5.27 µg/mL after 24 h and was also found to be non-toxic to normal cells (HEK). The AgNPs induced the fragmentation of DNA in the cells, indicating the occurrence of apoptosis and necrosis. Subsequently, an efficient larvae mortality was also recorded against Anopheles stephensi having LC50 and LC90 values being 8.969 and 16.102 ppm, followed by Aedes aegypti (LC50;14.791 and LC90;28.526 ppm) and Culex quinquefasciatus (LC50;18.662 and LC90;40.903 ppm) after 72 h of exposure. Besides, they showed no toxicity against Mesocyclops thermocyclopoides (non-target organism). This is the first report showing strong anti-tumorous and larvicidal activity of AgNPs synthesized using P. longum leaf extract against cervical cancer cell line and mosquito vectors causing dengue, malaria and filariasis. Based on our findings, we suggest that AgNPs derived using P. longum leaf extract possessed excellent anti-cancerous and mosquito larvicidal potential and therefore, can be bioprospected further for the management of these hazardous health diseases. This study has given a new insight for the novel drug designing after conducting experiments on the in vivo models.


Assuntos
Nanopartículas Metálicas/química , Piper/química , Extratos Vegetais/química , Prata/química , Aedes/efeitos dos fármacos , Animais , Anopheles/efeitos dos fármacos , Bioengenharia/métodos , Linhagem Celular , Linhagem Celular Tumoral , Culex/efeitos dos fármacos , Células HEK293 , Células HeLa , Humanos , Inseticidas/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Dose Letal Mediana , Extratos Vegetais/farmacologia
20.
J Am Mosq Control Assoc ; 35(2): 147-150, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31442130

RESUMO

Data on insecticide resistance in mosquitoes from Mississippi are reported. Mosquitoes were collected from June through October 2017 from 28 cities in Mississippi and included wild-caught Culex quinquefasciatus Say obtained as egg rafts (reared to adults), and Aedes albopictus (Skuse) collected as larvae (reared to adults). The Centers for Disease Control and Prevention (CDC) bottle bioassay protocol was utilized. Thirty-six populations of Cx. quinquefasciatus were tested for malathion resistance from 24 cities; 22 of them (61.1%) met the World Health Organization criteria as resistant, and the remaining 14 (38.9%) were classified suspected resistant. Forty-one populations of Cx. quinquefasciatus were also tested from 24 cities for resistance to permethrin, and of these, 18 populations (43.9%) were susceptible, 13 (31.7%) were resistant, and 10 (24.4%) were suspected resistance. Eighteen populations of Ae. albopictus were collected from 10 cities in Mississippi for resistance testing to malathion; 5 populations were susceptible (27.8%), 5 were resistant (27.8%), and 8 (44.4%) suspected resistant. Sixteen populations of Ae. albopictus were tested from 10 cities for resistance to permethrin and none were resistant.


Assuntos
Aedes/efeitos dos fármacos , Culex/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Aedes/fisiologia , Animais , Culex/fisiologia , Malation/farmacologia , Mississippi , Permetrina/farmacologia
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