RESUMO
Solanum mammosum (L.) is known as a poisonous plant and has been extensively used for anti-cancer, antifungal, antibacterial properties. However, the effectiveness of Solanum mammosum against insects has not been fully reported yet. To assess the ability of Solanum mammosum fruit extract against insects, we used fruit fly (Drosophila melanogaster) as a model. In this study, our results showed that phytochemicals and many secondary metabolites were present in Solanum mammosum fruit extracts such as alkaloids, saponins, tannins, terpenoids, coumarins, cardiac glycosides, steroidstriterpenoids, flavonoids, and phenolic compounds. The total polyphenol and flavonoid content were also determined to be 275±1.89 mg GAE/g extract and 676±5.14 mg QE/g extract, respectively. Besides, Solanum mammosum fruit extract caused lethal to 2nd instar, reduced a pupae formation rate of Drosophila larvae. Interestingly, Solanum mammosum extract is more effective in the suppression of pupae eclosion than Ascend as a commercial pesticide. These phenomena might be associated with reduced accumulation of energy, including carbohydrates, lipids, and protein. In addition, the activities of esterases and phosphatases were inhibited in Drosophila by the intake of Solanum mammosum. The study concluded that Solanum mammosum has great potential as an insecticidal agent.
Assuntos
Monoéster Fosfórico Hidrolases/análise , Solanum/química , Drosophila melanogaster , Esterases/análise , Inseticidas/análise , Controle de Insetos/métodos , Compostos Fitoquímicos/análiseRESUMO
Abstract: Objective: The feasibility of the use of WHO impregnated paper and biochemical assays to determine lethal concentrations (LC50 and LC99) and insecticide metabolic enzyme levels of Triatoma dimidiata. Materials and methods: LC50 and LC99 were calculated with WHO papers impregnated at different concentrations of malathion, propoxur and deltamethrin; the percentage of insensitive acetylcholinesterase (iAChE); and the levels of esterases, glutathione S-transferases, and monooxygenases in laboratory nymphs of the first stage (5 to 7 days), were undertaken using the WHO biochemical assays. Results: Respectively the LC50 and LC99 µg/cm2 obtained for malathion were 43.83 and 114.38, propoxur 4.71 and 19.29, and deltamethrin 5.80 and 40.46. A 30% of the population had an iAChE, and only a few individuals had high P450 and β-eterase levels. Conclusion: Impregnated papers and biochemical tests developed by WHO for other insects, proved to be feasible methods in monitoring insecticide resistance and metabolic enzymes involved in T. dimidiata.
Resumen: Objetivo: La factibilidad de usar los papeles impregnados y ensayos bioquímicos según la OMS para determinar concentraciones letales (CL50 y CL99) y niveles enzimáticos en la resistencia a insecticidas en Triatoma dimidiata. Material y métodos: Se calcularon la CL50 y CL99 con papeles impregnados según la OMS a diferentes concentraciones de malatión, propoxur y deltametrina; el porcentaje de acetilcolinesterasa insensible (iAChE); y los niveles de esterasas, glutatión S-transferasas, y monooxigenasas en ninfas de laboratorio del estadio I (5-7 días) se determinaron usando los ensayos bioquímicos según la OMS. Resultados: Se obtuvieron las CL50 y CL99 µg / cm2 respectivamente para malatión 43.83 y 114.38, propoxur 4.71 y 19.29, y deltametrina 5.80 y 40.46. Un 30% de las chinches tuvo iAChE, y sólo pocos individuos tuvieron niveles superiores de P450 y β-eterasas. Conclusión: Los papeles impregnados y ensayos bioquímicos que describe la OMS para otros insectos demostraron ser métodos factibles para monitorear la resistencia a insecticidas y las enzimas metabólicas involucradas en T. dimidiata.
Assuntos
Animais , Propoxur/toxicidade , Piretrinas/toxicidade , Triatoma/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/toxicidade , Malation/toxicidade , Nitrilas/toxicidade , Acetilcolinesterase/análise , Triatoma/enzimologia , Organização Mundial da Saúde , Estudos de Viabilidade , Sistema Enzimático do Citocromo P-450/análise , Esterases/análise , Glutationa Transferase/análise , Oxigenases de Função Mista/análise , Dose Letal Mediana , Ninfa/efeitos dos fármacos , Ninfa/enzimologiaRESUMO
BACKGROUND: Quizalofop-p-ethyl (QPE), a unitary R configuration aromatic oxyphenoxypropionic acid ester (AOPP) herbicide, was widely used and had led to detrimental environmental effects. For finding the QPEdegrading bacteria and promoting the biodegradation of QPE, a series of studies were carried out. RESULTS: A QPE-degrading bacterial strain YC-XJ1 was isolated from desert soil and identified as Methylobacterium populi, which could degrade QPE with methanol by cometabolism. Ninety-seven percent of QPE (50 mg/L) could be degraded within 72 h under optimum biodegradation condition of 35°C and pH 8.0. The maximum degradation rate of QPE was 1.4 mg/L/h, and the strain YC-XJ1 exhibited some certain salinity tolerance. Two novel metabolites, 2-hydroxy-6-chloroquinoxaline and quinoxaline, were found by high-performance liquid chromatography/mass spectroscopy analysis. The metabolic pathway of QPE was predicted. The catalytic efficiency of strain YC-XJ1 toward different AOPPs herbicides in descending order was as follows: haloxyfop-pmethyl ≈ diclofop-methyl ≈ fluazifop-p-butyl N clodinafop-propargyl N cyhalofop-butyl N quizalofop-p-ethyl N fenoxaprop-p-ethyl N propaquizafop N quizalofop-p-tefuryl. The genome of strain YC-XJ1 was sequenced using a combination of PacBio RS II and Illumina platforms. According to the annotation result, one α/ß hydrolase gene was selected and named qpeh1, for which QPE-degrading function has obtained validation. Based on the phylogenetic analysis and multiple sequence alignment with other QPE-degrading esterases reported previously, the QPEH1 was clustered with esterase family V. CONCLUSION: M. populi YC-XJ1 could degrade QPE with a novel pathway, and the qpeh1 gene was identified as one of QPE-degrading esterase gene.
Assuntos
Propionatos/metabolismo , Quinoxalinas/metabolismo , Methylobacterium/metabolismo , Microbiologia do Solo , Biodegradação Ambiental , Methylobacterium/enzimologia , Methylobacterium/genética , Análise de Sequência de Proteína , Esterases/análise , Esterases/metabolismo , Herbicidas , Hidrolases/análise , Hidrolases/metabolismo , HidróliseRESUMO
OBJECTIVE: The feasibility of the use of WHO impregnated paper and biochemical assays to determine lethal concentrations (LC50 and LC99) and insecticide metabolic enzyme levels of Triatoma dimidiata. MATERIALS AND METHODS: LC50 and LC99 were calculated with WHO papers impregnated at different concentrations of malathion, propoxur and deltamethrin; the percentage of insensitive acetylcholinesterase (iAChE); and the levels of esterases, glutathione S-transferases, and monooxygenases in laboratory nymphs of the first stage (5 to 7 days), were undertaken using the WHO biochemical assays. RESULTS: Respectively the LC50 and LC99 µg/cm2 obtained for malathion were 43.83 and 114.38, propoxur 4.71 and 19.29, and deltamethrin 5.80 and 40.46. A 30% of the population had an iAChE, and only a few individuals had high P450 and ß-eterase levels. CONCLUSIONS: Impregnated papers and biochemical tests developed by WHO for other insects, proved to be feasible methods in monitoring insecticide resistance and metabolic enzymes involved in T. dimidiata.
OBJETIVO: La factibilidad de usar los papeles impregnados y ensayos bioquímicos según la OMS para determinar concentraciones letales (CL50 y CL99) y niveles enzimáticos en la resistencia a insecticidas en Triatoma dimidiata. MATERIAL Y MÉTODOS: Se calcularon la CL50 y CL99 con papeles impregnados según la OMS a diferentes concentraciones de malatión, propoxur y deltametrina; el porcentaje de acetilcolinesterasa insensible (iAChE); y los niveles de esterasas, glutatión S-transferasas, y monooxigenasas en ninfas de laboratorio del estadio I (5-7 días) se determinaron usando los ensayos bioquímicos según la OMS. RESULTADOS: Se obtuvieron las CL50 y CL99 µg / cm2 respectivamente para malatión 43.83 y 114.38, propoxur 4.71 y 19.29, y deltametrina 5.80 y 40.46. Un 30% de las chinches tuvo iAChE, y sólo pocos individuos tuvieron niveles superiores de P450 y ß-eterasas. CONCLUSIONES: Los papeles impregnados y ensayos bioquímicos que describe la OMS para otros insectos demostraron ser métodos factibles para monitorear la resistencia a insecticidas y las enzimas metabólicas involucradas en T. dimidiata.
Assuntos
Resistência a Inseticidas , Inseticidas/toxicidade , Malation/toxicidade , Nitrilas/toxicidade , Propoxur/toxicidade , Piretrinas/toxicidade , Triatoma/efeitos dos fármacos , Acetilcolinesterase/análise , Animais , Sistema Enzimático do Citocromo P-450/análise , Esterases/análise , Estudos de Viabilidade , Glutationa Transferase/análise , Dose Letal Mediana , Oxigenases de Função Mista/análise , Ninfa/efeitos dos fármacos , Ninfa/enzimologia , Triatoma/enzimologia , Organização Mundial da SaúdeRESUMO
Esterases are enzymes that present good potential for industrial applications since they catalyze the formation or cleavage of ester bonds in water-soluble substrates, and sorghumseeds can represent an alternative source of this enzyme. The extraction of esterase from sorghumseeds is an economical alternative to obtain an enzyme of great interest. Esterases may improve the quality or accelerate the maturation of cheeses, cured bacon and fermented sausages and may also resolve racemic mixtures. Recently, seed esterases have been the focus of much attention as biocatalysts. In some cases, these enzymes present advantages over animal and microbial lipases due to some quite interesting features such as specificity and low cost, being a great alternative for their commercial exploitation as industrial enzymes The esterase studied here was extracted from sorghumseeds and some of its biochemical properties determined using synthetic substrates (p-nitrophenyl butyrate, caprylate, laurate and palmitate). The enzyme presented optimum activity at pH 8.0 and was stable in all the pH ranges studied. The optimum temperature for its activity was 40ºC but it showed low stability at this temperature (40% relative activity). The values derived for Km and Vmax were 0.67mM and 125 U.mg-1, respectively, obtained using p-nitrophenyl butyrate as the substrate. The enzyme showed an increase in activity when K2HPO4was added to the reaction medium, but the ions Mn2+, CO+, Hg+and Fe2+strongly inhibited the enzyme activity. This enzyme showed a preference for the hydrolysis of short chain fatty acids. The characteristics of sorghumesterase are very similar to those of the microbial esterases used in detergent processing.
Assuntos
Esterases/análise , Esterases/química , Sorghum/química , ÁlcalisRESUMO
Em Cabo Verde, arquipélago situado na Costa Ocidental Africana, os primeiros casos de dengue ocorreram em 2009, com a notificação de mais de 21.000 casos, a maioria desses registrados na Ilha de Santiago. O mosquito Aedes aegypti foi identificado como vetor, e ações para seu controle, usando os inseticidas temephos (larvicida) e a deltametrina (adulticida), têm sido implementadas. Objetiva-se com esse trabalho avaliar o atual status de suscetibilidade a inseticidas e caracterizar os mecanismos de resistência nessa população. Amostras de A. aegypti da ilha de Santiago foram coletadas através de armadilhas de oviposição, para o estabelecimento de uma população a ser analisada. Foram realizados bioensaios do tipo dose diagnóstica, usando garrafas impregnadas com doses únicas dos adulticidas malathion (organofosforado), deltametrina (piretróide) e cipermetrina (piretróide), e bioensaios do tipo dose resposta, usando múltiplas concentrações dos inseticidas temephos (organofosforado), Bacillus thuringiensis sorovariedade israelensis (bactéria entomopatogênica) e diflubenzuron (inibidor de síntese de quitina). Para a investigação dos mecanismos de resistências, foram realizados testes bioquímicos com substratos específicos para quantificar a atividade das enzimas glutationa S-transferases, esterases (alfa, beta e PNPA) e oxidases de função mista, ligadas a detoxificação de xenobióticos, e a taxa de inibição da acetilcolinesterase ligada a insensibilidade do sítio alvo...
Cape Verde, an archipelago located on the West African Coast, recorded the first cases of dengue in 2009 in an epidemic with more than 21,000 reportedcases. The worst affected area was Santiago Island...
Assuntos
Animais , Aedes , Enzimas/toxicidade , Insetos Vetores/virologia , Resistência a Inseticidas , África Ocidental , Bacillus thuringiensis/patogenicidade , Esterases/análise , Glutationa Transferase/análise , Malation/toxicidade , Testes de Toxicidade , Temefós/toxicidadeRESUMO
The aim of the present work was to study the deltamethrin susceptibility of eggs from Triatoma infestans populations and the contribution of pyrethroid esterases to deltamethrin degradation. Insects were collected from sylvatic areas, including Veinte de Octubre and Kirus-Mayu (Bolivia) and from domiciliary areas, including El Palmar (Bolivia) and La Pista (Argentina). Deltamethrin susceptibility was determined by dose-response bioassays. Serial dilutions of deltamethrin (0.0005-1 mg/mL) were topically applied to 12-day-old eggs. Samples from El Palmar had the highest lethal dose ratio (LDR) value (44.90) compared to the susceptible reference strain (NFS), whereas the Veinte de Octubre samples had the lowest value (0.50). Pyrethroid esterases were evaluated using 7-coumaryl permethrate (7-CP) on individually homogenised eggs from each population and from NFS. The El Palmar and La Pista samples contained 40.11 and 36.64 pmol/min/mg protein, respectively, and these values were statistically similar to NFS (34.92 pmol/min/mg protein) and different from Kirus-Mayu and Veinte de Octubre (27.49 and 22.69 pmol/min/mg protein, respectively). The toxicological data indicate that the domestic populations were resistant to deltamethrin, but no statistical contribution of 7-CP esterases was observed. The sylvatic populations had similar LDR values to NFS, but lower 7-CP esterase activities. Moreover, this is the first study of the pyrethroid esterases on T. infestans eggs employing a specific substrate (7-CP).
Assuntos
Animais , Esterases/análise , Nitrilas/farmacologia , Óvulo/efeitos dos fármacos , Piretrinas/farmacologia , Triatoma/efeitos dos fármacos , Bioensaio , Óvulo/enzimologia , Triatoma/enzimologiaRESUMO
A sensitive and efficient colorimetric method was optimized for detection of esterase enzymes produced by endophytic fungi for development of High-Throughput Screening (HTS). The fungi were isolated and obtained previously from plant species of Cerrado and Atlantic Forest located in areas of environmental preservation in the State of Sao Paulo / Brazil, as part of the project "Chemical and biological prospecting endophytic fungi associated to plant species of Cerrado and Atlantic Forest". The compounds ethyl butyrate, ethyl acetate and methyl propionate were used as standards esters which were hydrolyzed by extracellular enzyme from endophytic fungi (EC. 3.1.1.1 -carboxylesterases) for production of carboxylic acids. Thus, the reduction of the pH increases the protonated indicator concentration (bromothymol blue), changing the color of the reaction medium (from blue to yellow), that can be observed and measured by spectrophotometry at 616 nm. The methodology with acid-base indicator was performed on 13 microorganisms, aiming Periconia atropurpurea asapotential source of esterase for biotransformation of short chain esters. The results also evidenced that this methodology showed to be efficient, fast, cheap, having low consumption of reagents and easy development, and can be applied to screen carboxylic-ester hydrolases in a large number of microorganisms.
Assuntos
Colorimetria/métodos , Endófitos/enzimologia , Esterases/análise , Fungos/enzimologia , Acetatos/metabolismo , Brasil , Butiratos/metabolismo , Fungos/isolamento & purificação , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Plantas/microbiologia , Propionatos/metabolismoRESUMO
A sensitive and efficient colorimetric method was optimized for detection of esterase enzymes produced by endophytic fungi for development of High-Throughput Screening (HTS). The fungi were isolated and obtained previously from plant species of Cerrado and Atlantic Forest located in areas of environmental preservation in the State of Sao Paulo / Brazil, as part of the project "Chemical and biological prospecting endophytic fungi associated to plant species of Cerrado and Atlantic Forest". The compounds ethyl butyrate, ethyl acetate and methyl propionate were used as standards esters which were hydrolyzed by extracellular enzyme from endophytic fungi (EC. 3.1.1.1--carboxyl-esterases) for production of carboxylic acids. Thus, the reduction of the pH increases the protonated indicator concentration (bromothymol blue), changing the color of the reaction medium (from blue to yellow), that can be observed and measured by spectrophotometry at 616 nm. The methodology with acid-base indicator was performed on 13 microorganisms, aiming Periconia atropurpurea as a potential source of esterase for biotransformation of short chain esters. The results also evidenced that this methodology showed to be efficient, fast, cheap, having low consumption of reagents and easy development, and can be applied to screen carboxylic-ester hydrolases in a large number of microorganisms.
Assuntos
Colorimetria/métodos , Endófitos/enzimologia , Esterases/análise , Fungos/enzimologia , Acetatos/metabolismo , Brasil , Butiratos/metabolismo , Fungos/isolamento & purificação , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Plantas/microbiologia , Propionatos/metabolismoRESUMO
The aim of the present work was to study the deltamethrin susceptibility of eggs from Triatoma infestans populations and the contribution of pyrethroid esterases to deltamethrin degradation. Insects were collected from sylvatic areas, including Veinte de Octubre and Kirus-Mayu (Bolivia) and from domiciliary areas, including El Palmar (Bolivia) and La Pista (Argentina). Deltamethrin susceptibility was determined by dose-response bioassays. Serial dilutions of deltamethrin (0.0005-1 mg/mL) were topically applied to 12-day-old eggs. Samples from El Palmar had the highest lethal dose ratio (LDR) value (44.90) compared to the susceptible reference strain (NFS), whereas the Veinte de Octubre samples had the lowest value (0.50). Pyrethroid esterases were evaluated using 7-coumaryl permethrate (7-CP) on individually homogenised eggs from each population and from NFS. The El Palmar and La Pista samples contained 40.11 and 36.64 pmol/min/mg protein, respectively, and these values were statistically similar to NFS (34.92 pmol/min/mg protein) and different from Kirus-Mayu and Veinte de Octubre (27.49 and 22.69 pmol/min/mg protein, respectively). The toxicological data indicate that the domestic populations were resistant to deltamethrin, but no statistical contribution of 7-CP esterases was observed. The sylvatic populations had similar LDR values to NFS, but lower 7-CP esterase activities. Moreover, this is the first study of the pyrethroid esterases on T. infestans eggs employing a specific substrate (7-CP).
Assuntos
Esterases/análise , Nitrilas/farmacologia , Óvulo/efeitos dos fármacos , Piretrinas/farmacologia , Triatoma/efeitos dos fármacos , Animais , Bioensaio , Óvulo/enzimologia , Triatoma/enzimologiaRESUMO
Introducción. La resistencia fisiológica de las poblaciones naturales de Aedes aegypti a los insecticidas de uso en salud pública, disminuye la eficacia del control químico utilizado para interrumpir la transmisión de dengue durante los brotes y epidemias. Objetivo. Determinar el estado de la susceptibilidad al carbamato propoxur, a los organofosforados adulticidas malatión y fenitrotión y al larvicida temefos, de 13 poblaciones naturales de Ae. aegypti en ocho municipios: una de Bucaramanga y dos de Sabana de Torres en el departamento de Santander; dos de Girardot y dos de La Mesa en Cundinamarca; dos de Villavicencio y dos de Puerto López en el Meta; una de San José del Guaviare, en Guaviare, y una de Florencia en Caquetá. Materiales y métodos. Las pruebas de susceptibilidad consistieron en bioensayos estandarizados de la Organización Mundial de la Salud (OMS), 1981, y botellas de los Centers for Disease Control and Prevention (CDC), 1998. Se aplicaron pruebas colorimétricas para determinar los niveles de enzimas como posibles responsables de la reducción de la susceptibilidad a insecticidas organofosforados y al carbamato propoxur. Resultados. Todas las poblaciones presentaron susceptibilidad a malatión y propoxur. Para el temefos, solo cuatro de las trece localidades evaluadas registraron susceptibilidad. Con respecto a los posibles mecanismos de desintoxicación enzimática, en siete de las once poblaciones naturales se registraron valores superiores al punto de corte para esterasas inespecíficas, solamente en Bucaramanga se presentó un incremento en las enzimas monooxigenasas del citocromo P450, pero en ninguna población se registró acetilcolinestarasa modificada. Conclusiones. La susceptibilidad generalizada a los organofosforados adulticidas evaluados, indica que el malatión, el insecticida más utilizado en Colombia para interrumpir la transmisión del dengue, sigue siendo eficaz. Las particularidades de los resultados de la resistencia fisiológica a insecticidas de las comunas de un mismo municipio, evidenciaron un fenómeno localizado de manera específica en espacio y tiempo.
Introduction. Physiological resistance of natural population of Aedes aegypti to insecticides contribute to the decreased efficacy of chemical control as a main control strategy during dengue outbreaks. Objective. The susceptibility status of Ae. aegypti was assessed for the carbamate propoxur, the adulticide malathion and the larvicide temephos on 13 natural populations of Ae. aegypti immature forms were taken from 8 Colombian localities. These included the following: Bucaramanga (1), Sabana de Torres (2), Girardot (2), La Mesa (2), Villavicencio (2), Puerto López (2), San José del Guaviare (1) and Florencia (1). Materials and methods. Susceptibility tests mainly consisted of the standardized bioassay outlined by WHO (1981) and CDC bottles (1998). Colorimetric tests were undertaken to determine enzyme levels possibly responsible for the reduction of susceptibility to organophosphate and carbamate insecticides. Results. All specimens demonstrated susceptibility to malathion and propoxur insecticides. Four of the 13 populations revealed susceptibility to the temephos larvicide. Seven of 11 populations showed a limited increase in values for nonspecific esterase enzymes. The Bucaramanga population was the only one which showed an increase in the cytochrome P450 monooxygenases enzymes. Neither population was found with modified acetilcolinesterase. Conclusions. The widespread susceptibility to organophosphates used as adulticides indicated that malathion, the most used insecticide in Colombia, remains effective in interrupting the transmission of dengue. Physiological resistance to insecticides occurring in communities of a single township proved to be a localized phenomenon.
Assuntos
Animais , Feminino , Masculino , Aedes , Vírus da Dengue , Insetos Vetores , Resistência a Inseticidas , Inseticidas , Malation , Controle de Mosquitos , Propoxur , Temefós , Acetilcolinesterase/análise , Aedes/enzimologia , Aedes/crescimento & desenvolvimento , Colômbia , /análise , Resistência a Múltiplos Medicamentos , Esterases/análise , Proteínas de Insetos/análise , Larva , Saúde da População UrbanaRESUMO
OBJECTIVE: To examine the effects of increasing larval rearing temperatures on the resistance status of Trinidadian populations of Aedes aegypti to organophosphate (OP) insecticides. METHODS: In 2007-2008, bioassays and biochemical assays were conducted on A. aegypti larvae collected in 2006 from eight geographically distinct areas in Trinidad (Trinidad and Tobago). Larval populations were reared at four temperatures (28 ± 2ºC, 32ºC, 34ºC, and 36ºC) prior to bioassays with OP insecticides (fenthion, malathion, and temephos) and biochemical assays for esterase enzymes. RESULTS: Most larval populations reared at 28 ± 2ºC were susceptible to fenthion (>98% mortality) but resistant to malathion and temephos (< 80% mortality). A positive association was found between resistance to OP insecticides and increased activities of α- and ß-esterases in larval populations reared at 28 ± 2ºC. Although larval populations reared at higher temperatures showed variations in resistance to OPs, there was a general increase in susceptibility. However, increases or decreases in activity levels of enzymes did not always correspond with an increase or decrease in the proportion of resistant individuals reared at higher temperatures. CONCLUSIONS: Although global warming may cause an increase in dengue transmission, based on the current results, the use of insecticides for dengue prevention and control may yet be effective if temperatures increase as projected.
Assuntos
Aedes/efeitos dos fármacos , Fention/farmacologia , Insetos Vetores/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Malation/farmacologia , Temefós/farmacologia , Temperatura , Aedes/enzimologia , Aedes/crescimento & desenvolvimento , Animais , Dengue/prevenção & controle , Esterases/análise , Esterases/fisiologia , Aquecimento Global , Temperatura Alta , Proteínas de Insetos/análise , Proteínas de Insetos/fisiologia , Insetos Vetores/enzimologia , Insetos Vetores/crescimento & desenvolvimento , Resistência a Inseticidas/fisiologia , Larva/efeitos dos fármacos , Larva/enzimologia , Especificidade da Espécie , Trinidad e TobagoRESUMO
OBJECTIVE: To examine the effects of increasing larval rearing temperatures on the resistance status of Trinidadian populations of Aedes aegypti to organophosphate (OP) insecticides. METHODS: In 2007-2008, bioassays and biochemical assays were conducted on A. aegypti larvae collected in 2006 from eight geographically distinct areas in Trinidad (Trinidad and Tobago). Larval populations were reared at four temperatures (28 ± 2ºC, 32ºC, 34ºC, and 36ºC) prior to bioassays with OP insecticides (fenthion, malathion, and temephos) and biochemical assays for esterase enzymes. RESULTS: Most larval populations reared at 28 ± 2ºC were susceptible to fenthion (>98% mortality) but resistant to malathion and temephos (< 80% mortality). A positive association was found between resistance to OP insecticides and increased activities of α- and β-esterases in larval populations reared at 28 ± 2ºC. Although larval populations reared at higher temperatures showed variations in resistance to OPs, there was a general increase in susceptibility. However, increases or decreases in activity levels of enzymes did not always correspond with an increase or decrease in the proportion of resistant individuals reared at higher temperatures. CONCLUSIONS: Although global warming may cause an increase in dengue transmission, based on the current results, the use of insecticides for dengue prevention and control may yet be effective if temperatures increase as projected.
OBJETIVO: Examinar los efectos del aumento de las temperaturas de desarrollo larvario sobre el estado de resistencia a los insecticidas organofosforados de las poblaciones de Aedes aegypti en Trinidad. MÉTODOS: En 2007 y 2008 se llevaron a cabo ensayos biológicos y bioquímicos en larvas de A. aegypti recogidas en el 2006 de ocho áreas geográficamente separadas en Trinidad (Trinidad y Tabago). Las poblaciones larvarias se desarrollaron en cuatro temperaturas (28 ± 2 ºC, 32 ºC, 34 ºC y 36 ºC) antes de los ensayos biológicos con insecticidas organofosforados (fentión, malatión y temefós) y los análisis bioquímicos para las enzimas de esterasa. RESULTADOS: La mayoría de las poblaciones larvarias que se desarrollaron a 28 ± 2 ºC fueron susceptibles al fentión (mortalidad > 98%) pero resistentes al malatión y al temefós (mortalidad < 80%). Se encontró una asociación positiva entre la resistencia a los insecticidas organofosforados y la mayor actividad de αy β-esterasas en las poblaciones larvarias que se desarrollaron a 28 ± 2 ºC. Aunque las poblaciones larvarias que se desarrollaron a temperaturas mayores mostraron variaciones en la resistencia a los organofosforados, hubo un aumento general de la sensibilidad. Sin embargo, los aumentos o las disminuciones en los niveles de actividad de las enzimas no siempre se correspondieron con un aumento o disminución en la proporción de individuos resistentes desarrollados a las temperaturas más altas. CONCLUSIONES: Aunque el recalentamiento del planeta puede causar un aumento de la transmisión del dengue, según los resultados de este estudio el uso de insecticidas para la prevención y el control del dengue todavía puede ser eficaz si las temperaturas aumentan según lo proyectado.
Assuntos
Animais , Aedes/efeitos dos fármacos , Fention/farmacologia , Insetos Vetores/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Malation/farmacologia , Temefós/farmacologia , Temperatura , Aedes/enzimologia , Aedes/crescimento & desenvolvimento , Dengue/prevenção & controle , Esterases/análise , Esterases/fisiologia , Aquecimento Global , Temperatura Alta , Proteínas de Insetos/análise , Proteínas de Insetos/fisiologia , Insetos Vetores/enzimologia , Insetos Vetores/crescimento & desenvolvimento , Resistência a Inseticidas/fisiologia , Larva/efeitos dos fármacos , Larva/enzimologia , Especificidade da Espécie , Trinidad e TobagoRESUMO
INTRODUCTION: Physiological resistance of natural population of Aedes aegypti to insecticides contribute to the decreased efficacy of chemical control as a main control strategy during dengue outbreaks. OBJECTIVE: The susceptibility status of Ae. aegypti was assessed for the carbamate propoxur, the adulticide malathion and the larvicide temephos on 13 natural populations of Ae. aegypti immature forms were taken from 8 Colombian localities. These included the following: Bucaramanga (1), Sabana de Torres (2), Girardot (2), La Mesa (2), Villavicencio (2), Puerto López (2), San José del Guaviare (1) and Florencia (1). MATERIALS AND METHODS: Susceptibility tests mainly consisted of the standardized bioassay outlined by WHO (1981) and CDC bottles (1998). Colorimetric tests were undertaken to determine enzyme levels possibly responsible for the reduction of susceptibility to organophosphate and carbamate insecticides. RESULTS: All specimens demonstrated susceptibility to malathion and propoxur insecticides. Four of the 13 populations revealed susceptibility to the temephos larvicide. Seven of 11 populations showed a limited increase in values for nonspecific esterase enzymes. The Bucaramanga population was the only one which showed an increase in the cytochrome P450 monooxygenases enzymes. Neither population was found with modified acetilcolinesterase. CONCLUSIONS: The widespread susceptibility to organophosphates used as adulticides indicated that malathion, the most used insecticide in Colombia, remains effective in interrupting the transmission of dengue. Physiological resistance to insecticides occurring in communities of a single township proved to be a localized phenomenon.
Assuntos
Aedes , Vírus da Dengue , Insetos Vetores , Resistência a Inseticidas , Inseticidas , Malation , Controle de Mosquitos , Propoxur , Temefós , Acetilcolinesterase/análise , Aedes/enzimologia , Aedes/crescimento & desenvolvimento , Animais , Colômbia , Sistema Enzimático do Citocromo P-450/análise , Resistência a Múltiplos Medicamentos , Esterases/análise , Feminino , Proteínas de Insetos/análise , Larva , Masculino , Saúde da População UrbanaRESUMO
Snakes of the opisthoglyphous genus Philodryas are widespread in South America and cause most bites by colubrids in this region. In this study, we examined the neurotoxic and myotoxic effects of venom from Philodryas patagoniensis in biventer cervicis and phrenic nerve-diaphragm preparations and we compared the biochemical activities of venoms from P. patagoniensis and Philodryas olfersii. Philodryas patagoniensis venom (40 microg/mL) had no effect on mouse phrenic nerve-diaphragm preparations but caused time-dependent neuromuscular blockade of chick biventer cervicis preparations. This blockade was not reversed by washing. The highest concentration of venom tested (40 microg/mL) significantly reduced (p<0.05) the contractures to exogenous acetylcholine (55 microM and 110 microM) and K(+) (13.4 mM) after 120 min; lower concentrations of venom had no consistent or significant effect on these responses. Venom caused a concentration- and time-dependent release of creatine kinase (CK) from biventer cervicis preparations. Histological analysis showed contracted muscle fibers at low venom concentrations and myonecrosis at high concentrations. Philodryas venoms had low esterase and phospholipase A(2) but high proteolytic activities compared to the pitviper Bothrops jararaca. SDS-PAGE showed that the Philodryas venoms had similar electrophoretic profiles, with most proteins having a molecular mass of 25-80 kDa. Both of the Philodryas venoms cross-reacted with bothropic antivenom in ELISA, indicating the presence of proteins immunologically related to Bothrops venoms. RP-HPLC of P. patagoniensis venom yielded four major peaks, each of which contained several proteins, as shown by SDS-PAGE. These results indicate that P. patagoniensis venom has neurotoxic and myotoxic components that may contribute to the effects of envenoming by this species.
Assuntos
Colubridae/metabolismo , Contração Muscular/efeitos dos fármacos , Bloqueadores Neuromusculares/farmacologia , Junção Neuromuscular/efeitos dos fármacos , Venenos de Serpentes/farmacologia , Animais , Antivenenos/metabolismo , Bothrops , Galinhas , Cromatografia Líquida de Alta Pressão , Reações Cruzadas , Venenos de Crotalídeos/metabolismo , Diafragma/efeitos dos fármacos , Diafragma/inervação , Relação Dose-Resposta a Droga , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Esterases/análise , Técnicas In Vitro , Masculino , Camundongos , Peso Molecular , Necrose , Bloqueadores Neuromusculares/metabolismo , Junção Neuromuscular/patologia , Peptídeo Hidrolases/análise , Fosfolipases A2/análise , Nervo Frênico/efeitos dos fármacos , Venenos de Serpentes/enzimologia , Venenos de Serpentes/metabolismo , América do Sul , Fatores de TempoRESUMO
Se realizó un estudio in vivo a través del uso de 2 sinergistas, el trifenil fosfato (TFF) inhibidor específico de esterasas y el ácido etacrínico (AE), inhibidor específico de la enzima glutation transferasa (GST), para determinar si estas enzimas eran responsables de la resistencia a piretroides en Aedes aegypti. Para el trabajo se utilizaron 2 cepas de Aedes aegypti resistentes a insecticidas, una cepa que fue seleccionada con temefos por 6 generaciones de selección (SAN-F6) y otra con deltametrina por 12 generaciones de selección con este insecticida (SAN-F12), ambas resultaron ser resistentes a insecticidas piretroides. Se demostró a través del uso de los sinergistas TFF y AE que las enzimas esterasas y GST son responsables de la resistencia a los piretroides en estas cepas. Esos resultados demuestran la existencia de un fenómeno de resistencia cruzada y multirresistencia, lo cual debe tenerse en cuenta en las estrategias de uso de insecticidas para el control de este vector.
An in vivo study of two synergists, that is, Triphenil phosphate -specific esterase inhibitor- and ethacrynic acid specific gluthation transferase inhibitor- was performed to determine if these enzymes were responsible for pyrethroid resistance of Aedes aegypti. To this end, two insecticide resistant Aedes aegypti strains were used, one strain selected with temephos by six selection generations (SAN-F6) and the other strain with delmamethrin by 12 selection generations (SAN-F12), being both strains resistant to pyrethroid insecticices. Through the use of TPP and EA synergists, it was proved that esterase and gluthation-s-transferase (GST) enzymes were responsible for pryrethroid resistance of these strains. These results showed the existence of cross-resistance and multidrug resistance, which should be taken into account for insecticide use strategies aimed at vector control.
Assuntos
Aedes/enzimologia , Esterases/análise , Transferases/análiseRESUMO
OBJECTIVE: To diagnose susceptibility levels and insecticide resistance mechanisms in Anopheles albimanus from the southern Yucatan Peninsula (YP), Mexico. MATERIAL AND METHODS: F1 generation of An. albimanus females, collected from November to December 2005 in six villages in the Othon P. Blanco municipality in Quintana Roo and the Calakmul municipality in Campeche, were exposed to deltamethrin, DDT, pirimiphos-methyl and bendiocarb in susceptibility tests, as well as to biochemical assays in order to calculate the enzyme levels related to insecticide resistance. RESULTS: High levels of DDT and deltamethrin resistance were found in An. albimanus collected from the six villages, and a high resistance to pirimiphos-methyl was found in those from La Union, Quintana Roo. Biochemical assays showed high levels of glutathione S-transferase (GST), cytochrome P450 and esterases (with pNPA substrate) in all villages. The frequency of An. albimanus with altered acetylcholinesterase (AChE) was high in La Union (33%). CONCLUSIONS: The An. albimanus populations collected in the south of the YP are resistant to DDT and deltamethrin, whereas resistance to pirimiphos-methyl was significant only in those collected from La Union. The mechanisms explaining this resistance are based on high concentrations of GST, cytochrome P450 and esterasas, the former being responsible for DDT metabolism and the others for pyrethroid metabolism. The altered AChE was the mechanism correlated to pirimiphos-methyl resistance in La Union. The results of the present study have important practical consequences for the chemical control of An. albimanus in the south of the YP.
Assuntos
Anopheles , Inseticidas , Acetilcolinesterase/análise , Animais , Anopheles/enzimologia , Sistema Enzimático do Citocromo P-450/análise , DDT , Interpretação Estatística de Dados , Esterases/análise , Feminino , Glutationa Transferase/análise , Resistência a Inseticidas/efeitos dos fármacos , México , Controle de Mosquitos , Nitrilas , Compostos Organotiofosforados , Piretrinas , Estações do AnoRESUMO
OBJETIVOS: Diagnosticar la resistencia a insecticidas y sus mecanismos en Anopheles albimanus del sur de la Península de Yucatán (PY), México. MATERIAL Y MÉTODOS: La F1 de An. albimanus colectados durante noviembre-diciembre de 2005 en seis localidades de los municipios Othón P. Blanco en Quintana Roo y Calakmul en Campeche, fue sometida a pruebas de susceptibilidad con deltametrina, DDT, pirimifos metil y bendiocarb, y a pruebas bioquímicas para calcular los niveles de las enzimas involucradas en la resistencia. RESULTADOS: An. albimanus fue resistente al DDT y a deltametrina en las seis localidades con niveles elevados de glutatión S-transferasas (GSTs), monooxigenasas y esterasas, y a pirimifos metil en La Unión con una alta frecuencia de la acetilcolinesterasa (AChE) alterada. CONCLUSION: Las poblaciones de An. albimanus colectadas al sur de la PY son resistentes al DDT y deltametrina, y en La Unión además al pirimifos metil, con mecanismos basados en la AChE alterada para el pirimifos metil, GST para DDT, y monooxigenasas y esterasas para piretroides. Los resultados del presente estudio tienen importantes consecuencias prácticas para el control químico de An. albimanus en el sur de la PY.
OBJECTIVE: To diagnose susceptibility levels and insecticide resistance mechanisms in Anopheles albimanus from the southern Yucatan Peninsula (YP), Mexico. MATERIAL AND METHODS: F1 generation of An. albimanus females, collected from November to December 2005 in six villages in the Othon P. Blanco municipality in Quintana Roo and the Calakmul municipality in Campeche, were exposed to deltamethrin, DDT, pirimiphos-methyl and bendiocarb in susceptibility tests, as well as to biochemical assays in order to calculate the enzyme levels related to insecticide resistance. RESULTS: High levels of DDT and deltamethrin resistance were found in An. albimanus collected from the six villages, and a high resistance to pirimiphos-methyl was found in those from La Union, Quintana Roo. Biochemical assays showed high levels of glutathione S-transferase (GST), cytochrome P450 and esterases (with pNPA substrate) in all villages. The frequency of An. albimanus with altered acetylcholinesterase (AChE) was high in La Union (33 percent). CONCLUSIONS: The An. albimanus populations collected in the south of the YP are resistant to DDT and deltamethrin, whereas resistance to pirimiphos-methyl was significant only in those collected from La Union. The mechanisms explaining this resistance are based on high concentrations of GST, cytochrome P450 and esterasas, the former being responsible for DDT metabolism and the others for pyrethroid metabolism. The altered AChE was the mechanism correlated to pirimiphos-methyl resistance in La Union. The results of the present study have important practical consequences for the chemical control of An. albimanus in the south of the YP.
Assuntos
Animais , Feminino , Anopheles , Inseticidas , DDT , Acetilcolinesterase/análise , Anopheles/enzimologia , /análise , Interpretação Estatística de Dados , Esterases/análise , Glutationa Transferase/análise , Resistência a Inseticidas/efeitos dos fármacos , México , Controle de Mosquitos , Nitrilas , Compostos Organotiofosforados , Piretrinas , Estações do AnoRESUMO
Insecticide resistance of Aedes aegypti larvae and adults from two Peruvian provinces, that is, Trujillo and Tumbes provinces, was conducted. High infestation indexes and extensive use of insecticides based on the Vector Surveillance and Control Strategy of the Ministry of Public Health prevailed in these places. Larval bioassays revealed susceptibility to organophosphorate insecticide called malathion in TRUJILLO strain, it being moderate to fention and fenitrotion and high to chlorpyriphos and temephos;however, TUMBES strain was susceptible to the evaluated organophosphorate compounds, except for fention, with moderate resistance. In the adult state, at the recommended dose, TRUJILLO strain showed resistence to DDT organochlorate insecticide and to pyrethoids called lambdacyalotrine and cyflutrine whereas TUMBES was resistant to DDT and to all assessed pyrethoids. None of them was resistant to chlorpiriphos in adult stage. By using synergists, the results showed that esterases and monooxigenases played an important role in the detected resistence to organophosphorate in Aedes larvae from TRUJILLO province. Biochemical assays yielded that increased activity of esterases was very frequent in TRUJILLO strain as was the case of glutathion transferase(GST) and modified acetylcholinesterase (AchR). On the other hand, the polyacrylamide gel electrophoresis allowed observing the prevalence of amplified activity of esterases A4 in TRUJILLO strain but not in TUMBES strain.
Assuntos
Aedes/fisiologia , Insetos Vetores/fisiologia , Resistência a Inseticidas/fisiologia , Aedes/efeitos dos fármacos , Aedes/enzimologia , Aedes/genética , Aedes/crescimento & desenvolvimento , Animais , Sinergismo Farmacológico , Esterases/análise , Esterases/fisiologia , Feminino , Glutationa Transferase/análise , Glutationa Transferase/fisiologia , Inativação Metabólica , Proteínas de Insetos/análise , Proteínas de Insetos/fisiologia , Insetos Vetores/efeitos dos fármacos , Insetos Vetores/enzimologia , Insetos Vetores/genética , Resistência a Inseticidas/genética , Inseticidas/classificação , Inseticidas/farmacocinética , Inseticidas/farmacologia , Larva , Dose Letal Mediana , Peru , Especificidade da EspécieRESUMO
An in vivo study of two synergists, that is, Triphenil phosphate -specific esterase inhibitor- and ethacrynic acid -specific gluthation transferase inhibitor- was performed to determine if these enzymes were responsible for pyrethroid resistance of Aedes aegypti. To this end, two insecticide resistant Aedes aegypti strains were used, one strain selected with temephos by six selection generations (SAN-F6) and the other strain with delmamethrin by 12 selection generations (SAN-F12), being both strains resistant to pyrethroid insecticices. Through the use of TPP and EA synergists, it was proved that esterase and gluthation-s-transferase (GST) enzymes were responsible for pryrethroid resistance of these strains. These results showed the existence of cross-resistance and multidrug resistance, which should be taken into account for insecticide use strategies aimed at vector control.