Página 1 dos resultados de 748 itens digitais encontrados em 0.001 segundos

‣ Knockdown resistance in pyrethroid-resistant horn fly (Diptera: Muscidae) populations in Brazil

SABATINI, Gustavo A.; RIBOLLA, Paulo E. M.; BARROS, Antonio T. M.; GUERRERO, Felix D.; SCHUMAKER, Terezinha T. S.
Fonte: BRAZILIAN COLL VETERINARY PARASITOLOGY Publicador: BRAZILIAN COLL VETERINARY PARASITOLOGY
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.246926%
To investigate the kdr (knockdown resistance) resistance-associated gene mutation and determine its frequency in pyrethroid-resistant horn fly (Haematobia irritans) populations, a total of 1,804 horn flies of 37 different populations from all Brazilian regions (North, Northeast, Central-West, Southeast, and South) were molecular screened through polymerase chain reaction (PCR). The kdr gene was not detected in 87.08% of the flies. However, the gene was amplified in 12.92% of the flies, of which 11.70% were resistant heterozygous and 1.22% were resistant homozygous. Deviation from Hardy-Weinberg equilibrium (HWE) was found only in 1 ranch with an excess of heterozygous. When populations were grouped by region, three metapopulations showed significant deviations of HWE (Central-West population, South population and Southeast population). This indicates that populations are isolated one from another and kdr occurrence seems to be an independent effect probably reflecting the insecticide strategy used by each ranch. Although resistance to pyrethroids is disseminated throughout Brazil, only 48% of resistant populations had kdr flies, and the frequency of kdr individuals in each of these resistant populations was quite low. But this study shows that...

‣ Knockdown resistance in pyrethroid-resistant horn fly (Diptera: Muscidae) populations in Brazil

Sabatini, Gustavo A.; Ribolla, Paulo E. M.; Barros, Antonio T. M.; Guerrero, Felix D.; Schumaker, Terezinha T. S.
Fonte: Colégio Brasileiro de Parasitologia Veterinária Publicador: Colégio Brasileiro de Parasitologia Veterinária
Tipo: Artigo de Revista Científica Formato: 8-14
Português
Relevância na Pesquisa
37.246926%
Com o objetivo de verificar a ocorrência e determinar a frequência da mutação kdr (knock down resistance) em populações de Haematobia irritans (mosca-dos-chifres) resistentes aos piretróides, foram analisados 1.804 indivíduos de 37 populações de todas as Regiões do Brasil. Com exceção da Região Nordeste, o kdr (knock down resistance gene) foi encontrado em populações de todas as regiões. A mutação não foi detectada em 87,08% dos indivíduos. Entretanto, o gene foi amplificado de 12,92% das moscas, das quais 11,70% se mostraram heterozigotas resistentes e 1,22% homozigotas resistentes. em todas as populações verificou-se equilíbrio de acordo com a Lei de Hardy e Weinberg, exceto uma com excesso de heterozigotos. Entretanto, quando agrupamos diferentes populações numa metapopulação de acordo com a região geográfica, é possível observar um desvio nas populações Centro-Oeste, Sul e Sudeste, indicando isolamento populacional e que a ocorrência do kdr é provavelmente um efeito independente, talvez refletindo a estratégia de uso do inseticida de cada produtor. Apesar da resistência aos piretróides estar disseminada por todo o país, apenas 48% das populações resistentes apresentaram o kdr, e a frequência de indivíduos kdr nas populações resistentes se mostrou bastante baixa. À exceção da Região Nordeste...

‣ Pyrethroid residues in milk and blood of dairy cows following single topical applications

Bissacot, Denise Zuccari; Vassilieff, Igor
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 6-8
Português
Relevância na Pesquisa
37.08643%
The presence of the pyrethroid insecticides flumethrin, deltamethrin, cypermethrin and cyhalothrin in milk and blood of 10 cows was determined after single dermal applications of recommended doses. Milk and blood samples were collected every 7 days over a 35 d period and analyzed by high performance liquid chromatography. The highest residues in milk were found on day 28 for flumethrin and day 1 for deltamethrin, cypermethrin and cyhalothrin, while in blood the highest concentrations were present on day 28 for flumethrin and deltamethrin, the first day for cypermethrin, and day 14 for cyhalothrin.

‣ Effects of deltamethrin pyrethroid on the respiratory metabolism of the neotropical spirostreptid millipedes Gymnostreptus olivaceus and Plusioporus setiger

Boccardo, Lilian; Fernandes, Marisa N.; Penteado, Carlos H.S.; Jucá-Chagas, Ricardo
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 25-28
Português
Relevância na Pesquisa
37.43417%
The effects of deltamethrin on the respiratory metabolism of Gymnostreptus olivaceus and Plusioporus setiger were investigated. Acetone solutions corresponding to half the LD50 values, i.e., 20 μg.g-1g for G. olivaceus and 4.40 μg.g-1 for P. setiger, were used. Metabolism was determined with a Warburg respirometer at 25°C. Respirometric measurements were performed 1, 3 and 6 hours after administration of the pyrethroid to the same groups of millipedes. After 24 hours, daily respirometric measurements lasting 1 hour each were made on different millipede groups for a period of 10 days. Significant differences were detected only between the groups treated with the pyrethroid and the two control groups. In G. olivaceus, respiratory rates increased by about 1.65-fold compared to normal immediately after administration of the pyrethroid, followed by a gradual decrease up to 72 hours and a return to normal levels thereafter. In P. setiger the increase was about 1.1-fold compared to normal, with a decrease up to 96 hours and a return to normal thereafter. Although increased oxygen consumption was observed, a detoxification process occurred in both species, so that the possible metabolism of the pyrethroid may justify the low toxicity of deltamethrin for G. olivaceus and P. setiger.

‣ Monitoring of resistance to the pyrethroid cypermethrin in Brazilian Aedes aegypti (Diptera: Culicidae) populations collected between 2001 and 2003

da-Cunha,Marcella Pereira; Lima,José Bento Pereira; Brogdon,William G; Moya,Gonzalo Efrain; Valle,Denise
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2005 Português
Relevância na Pesquisa
37.08643%
Resistance to cypermethrin of different Aedes aegypti Brazilian populations, collected at two successive periods (2001 and 2002/2003), was monitored using the insecticide-coated bottles bioassay. Slight modifications were included in the method to discriminate between mortality and the knock down effect. Although this pyrethroid was recently started to be used in the country to control the dengue vector, a decrease in susceptibility was noted between both periods analyzed, particularly in the city of Rio de Janeiro. The results indicate that resistance is due at least in part to a target site alteration.

‣ Toxicity of non-pyrethroid insecticides against Triatoma infestans (Hemiptera: Reduviidae)

Carvajal,Guillermo; Mougabure-Cueto,Gastón; Toloza,Ariel Ceferino
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 Português
Relevância na Pesquisa
37.35565%
Triatoma infestans (Klug) is the main vector of Chagas disease, which is a public health concern in most Latin American countries. The prevention of Chagas disease is based on the chemical control of the vector using pyrethroid insecticides. In the last decade, different levels of deltamethrin resistance have been detected in certain areas of Argentina and Bolivia. Because of this, alternative non-pyrethroid insecticides from different chemical groups were evaluated against two T. infestans populations, NFS and El Malá, with the objective of finding new insecticides to control resistant insect populations. Toxicity to different insecticides was evaluated in a deltamethrin-susceptible and a deltamethrin-resistant population. Topical application of the insecticides fenitrothion and imidacloprid to first nymphs had lethal effects on both populations, producing 50% lethal dose (LD50) values that ranged from 5.2-28 ng/insect. However, amitraz, flubendiamide, ivermectin, indoxacarb and spinosad showed no insecticidal activity in first instars at the applied doses (LD50 > 200 ng/insect). Fenitrothion and imidacloprid were effective against both deltamethrin-susceptible and deltamethrin-resistant populations of T. infestans. Therefore, they may be considered alternative non-pyrethroid insecticides for the control of Chagas disease.

‣ Analysing deltamethrin susceptibility and pyrethroid esterase activity variations in sylvatic and domestic Triatoma infestans at the embryonic stage

Santo-Orihuela,Pablo Luis; Carvajal,Guillermo; Picollo,Maria Ines; Vassena,Claudia Viviana
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 Português
Relevância na Pesquisa
37.43417%
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...

‣ Pyrethroid toxicity in silver catfish, Rhamdia quelen

Montanha,Francisco P.; Galeb,Luciana A.G.; Mikos,Jorge D.; Ganeco,Luciana N.; Pereira,Tiago P.; Tanaka,Anne; Kirschnik,Peter G.; Pimpão,Cláudia T.
Fonte: Colégio Brasileiro de Patologia Animal - CBPA; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Publicador: Colégio Brasileiro de Patologia Animal - CBPA; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 Português
Relevância na Pesquisa
37.08643%
This study aimed to determine both the lethal and sublethal concentrations of Cypermethrin in young Silver Catfish (Brazilian "Jundiá", Rhamdia quelen) on aquatic environment during 96 hours, as well as to determine the Cypermethrin and Deltamethrin sublethal concentrations during the initial embryonic development period of Rhamdia quelen, and to verify their respective rates of fertilization, hatching and survival. Pyrethroid nowadays is a widely used insecticide, which presents a high toxicity to fish. In order to determine lethal and sublethal concentrations, 120 silver catfish were used; each one had an average weight of 59.58±4.50g and an average size of 20.33±2.34cm. Concentrations used were 0, 1.0, 1.5, 2.0, 2.5, 3.0, 5.0, 10.0, 15.0 and 20.0mg of Cypermethrin per liter of water (mg/L). Fish were exposed to the product in 30-liter fish tanks. In each fish tank there were four fishes and the product was applied three times, i.e., a total of twelve fish were exposed to the product at each application, and a total of 120 fish during the entire experiment (n=120). In order to determine the Cypermethrin and Deltamethrin sublethal concentrations during the initial embryonic development, ovulation induction was performed on female fishes using hormones...

‣ Determination of pyrethroid pesticides in environmental samples using ionic liquid dispersive liquid-liquid microextraction

Wu,Tong; Liu,Yu; Yang,Zhonghua; Gao,Haixiang; Zhou,Zhiqiang
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2012 Português
Relevância na Pesquisa
37.08643%
Dispersive liquid-liquid microextraction (DLLME) using ionic liquid (IL) as extraction solvent was developed as a new approach for the determination of four pyrethroid pesticides in environmental water and soil samples. High-performance liquid chromatography with ultraviolet detection (HPLC-UV) was employed on chromatographic analysis. The method is rapid, easy to operate and enviromentally-friendly. The highly toxic chlorinated solvent was replaced by the IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]), in which high extraction recovery and enrichment factors were obtained. The effects of IL volume, type and volume of disperser solvent, salt addition, pH and extraction time were investigated and optimized. Under optimum conditions, the method showed good linear response with correlation coefficient (R²) values in the range of 0.9943 to 0.9986. Relative standard deviation (RSD) varied from 3.9 to 10.1%. Enrichment factor, limit of detection and recovery ranged from 260 to 319, 0.94 to 1.97 µg L-1 and 89 to 98%, respectively. For real water samples, RSD ranged from 3.8 to 10.8%, and recovery from 83 to 99%. For soil sample analysis, RSD and recovery ranged from 3.7 to 8.9% and 88 to 98, respectively.

‣ Simultaneous determination of the organochlorine and pyrethroid pesticides in drinking water by single drop microextraction and gas chromatography

Carlos,Elenice A.; Alves,Renata D.; Queiroz,Maria Eliana L. R. de; Neves,Antônio A.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2013 Português
Relevância na Pesquisa
37.08643%
A method for simultaneous determination of 14 pesticides (organochlorine and pyrethroid) in water was developed using the single drop microextraction (SDME) and gas chromatography with an electron capture detector. Experimental variables including organic solvent, volume of the microdrop, extraction time, volume and stirring speed of the sample and the addition of salt were evaluated to maximize the performance of the SDME technique. Coefficients of variation (CV) lower than 20% and relative recoveries between 71 and 107% indicated good precision and accuracy of the method. The developed protocol also showed selectivity and good linearity with correlation coefficients (r) greater than 0.99. Limits of detection of the analytes of interest were between 0.003 and 0.6 µg L-1, all below the respective maximum contaminant levels (MCL) for drinking water. Drinking water samples were analyzed using the proposed method and none of the pesticides were detected.

‣ Knockdown resistance in pyrethroid-resistant horn fly (Diptera: Muscidae) populations in Brazil

Sabatini,Gustavo A.; Ribolla,Paulo E. M.; Barros,Antonio T. M.; Guerrero,Felix D.; Schumaker,Terezinha T. S.
Fonte: Colégio Brasileiro de Parasitologia Veterinária Publicador: Colégio Brasileiro de Parasitologia Veterinária
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2009 Português
Relevância na Pesquisa
37.246926%
To investigate the kdr (knockdown resistance) resistance-associated gene mutation and determine its frequency in pyrethroid-resistant horn fly (Haematobia irritans) populations, a total of 1,804 horn flies of 37 different populations from all Brazilian regions (North, Northeast, Central-West, Southeast, and South) were molecular screened through polymerase chain reaction (PCR). The kdr gene was not detected in 87.08% of the flies. However, the gene was amplified in 12.92% of the flies, of which 11.70% were resistant heterozygous and 1.22% were resistant homozygous. Deviation from Hardy-Weinberg equilibrium (HWE) was found only in 1 ranch with an excess of heterozygous. When populations were grouped by region, three metapopulations showed significant deviations of HWE (Central-West population, South population and Southeast population). This indicates that populations are isolated one from another and kdr occurrence seems to be an independent effect probably reflecting the insecticide strategy used by each ranch. Although resistance to pyrethroids is disseminated throughout Brazil, only 48% of resistant populations had kdr flies, and the frequency of kdr individuals in each of these resistant populations was quite low. But this study shows that...

‣ An epidemiological study on occupational acute pyrethroid poisoning in cotton farmers.

Chen, S Y; Zhang, Z W; He, F S; Yao, P P; Wu, Y Q; Sun, J X; Liu, L H; Li, Q G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1991 Português
Relevância na Pesquisa
27.49354%
A cross sectional survey on the prevalence of acute pyrethroid poisoning in cotton farmers was conducted in 1987 and 1988. A total of 3113 pyrethroid spraymen (2230 men (71.6%) and 883 women (28.4%] were interviewed after spraying and followed up for 72 hours. Adverse effects of pyrethroid exposure were found in 834 of them (26.8%) manifested as abnormal facial sensations, dizziness, headache, fatigue, nausea, or loss of appetite. Only 10 subjects, who developed significant systemic symptoms and had signs of listlessness or muscular fasciculation, were diagnosed as having mild occupational acute pyrethroid poisoning with a prevalence of 0.31% in subjects exposed to pure pyrethroids and 0.38% in subjects exposed to pyrethroid organophosphate mixtures. Measurements of pyrethroid concentrations in the air of the breathing zone, in skin pads, and in urine samples showed that dermal contamination is the main route of exposure to pyrethroids in cotton growers. Preventive measures are recommended.

‣ Influence of container adsorption upon observed pyrethroid toxicity to Ceriodaphnia dubia and Hyalella azteca

Wheelock, Craig E.; Miller, Jeff L.; Miller, Mike J.; Phillips, Bryn M.; Gee, Shirley J.; Tjeerdema, Ronald S.; Hammock, Bruce D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/08/2005 Português
Relevância na Pesquisa
27.577356%
Pyrethroid insecticides are known for their potential toxicity to aquatic invertebrates and many fish species. A significant problem in the study of pyrethroid toxicity is their extreme hydrophobicity. They can adsorb to test container surfaces and many studies, therefore, report pyrethroid levels as nominal water concentrations. In this study, pyrethroid adsorption to sampling and test containers was measured and several container treatments were examined for their ability to decrease pyrethroid adsorption. None of the chemical treatments were successful at preventing pyrethroid loss from aqueous samples, but vortexing of containers served to resuspend pyrethroids. The effects of the observed adsorption on Ceriodaphnia dubia and Hyalella azteca permethrin toxicity were examined. Species-specific results showed a time-dependent decrease in toxicity following pyrethroid adsorption to test containers for C. dubia, but not for H. azteca. These results demonstrate that pyrethroid adsorption to containers can significantly affect the observed outcome in toxicity-testing and serves as a caution for researchers and testing laboratories.

‣ A Longitudinal Approach to Assessing Urban and Suburban Children’s Exposure to Pyrethroid Pesticides

Lu, Chensheng; Barr, Dana B.; Pearson, Melanie; Bartell, Scott; Bravo, Roberto
Fonte: National Institute of Environmental Health Sciences Publicador: National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.49354%
We conducted a longitudinal study to assess the exposure of 23 elementary school–age children to pyrethroid pesticides, using urinary pyrethroid metabolites as exposure biomarkers. We substituted most of the children’s conventional diets with organic food items for 5 consecutive days and collected two daily spot urine samples, first morning and before bedtime voids, throughout the 15-day study period. We analyzed urine samples for five common pyrethroid metabolites. We found an association between the parents’ self-reported pyrethroid use in the residential environment and elevated pyrethroid metabolite levels found in their children’s urine. Children were also exposed to pyrethroids through their conventional diets, although the magnitude was smaller than for the residential exposure. Children’s ages appear to be significantly associated with pyrethroids exposure, which is likely attributed to the use of pyrethroids around the premises or in the facilities where older children engaged in the outdoor activities. We conclude that residential pesticide use represents the most important risk factor for children’s exposure to pyrethroid insecticides. Because of the wide use of pyrethroids in the United States, the findings of this study are important for both children’s pesticide exposure assessment and environmental public health.

‣ Comparative performances, under laboratory conditions, of seven pyrethroid insecticides used for impregnation of mosquito nets.

Hougard, Jean-Marc; Duchon, Stéphane; Darriet, Frédéric; Zaim, Morteza; Rogier, Christophe; Guillet, Pierre
Fonte: World Health Organization Publicador: World Health Organization
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.49354%
OBJECTIVE: To compare the efficacy of seven pyrethroid insecticides for impregnation of mosquito nets, six currently recommended by WHO and one candidate (bifenthrin), under laboratory conditions. METHODS: Tests were conducted using pyrethroid-susceptible and pyrethroid-resistant strains of Anopheles gambiae and Culex quinquefasciatus. Knock-down effect, irritancy and mortality were measured using standard WHO cone tests. Mortality and blood-feeding inhibition were also measured using a baited tunnel device. FINDINGS: For susceptible A. gambiae, alpha-cypermethrin had the fastest knock-down effect. For resistant A. gambiae, the knock- down effect was slightly slower with alpha-cypermethrin and much reduced following exposure to the other insecticides, particularly bifenthrin and permethrin. For susceptible C. quinquefasciatus, the knock-down effect was significantly slower than in A. gambiae, particularly with bifenthrin, and no knock-down effect was observed with any of the pyrethroids against the resistant strain. Bifenthrin was significantly less irritant than the other pyrethroids to susceptible and resistant A. gambiae but there was no clear ranking of pyrethroid irritancy against C. quinquefasciatus. In tunnels, all insecticides were less toxic against C. quinquefasciatus than against A. gambiae for susceptible strains. For resistant strains...

‣ Pyrethroid Resistance in the Tobacco Budworm (Lepidoptera: Noctuidae): Insecticide Bioassays and Field Monitoring

Campanhola, C.; Plapp, F. W.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
Português
Relevância na Pesquisa
37.246926%
Resistance to pyrethroid insecticides in the tobacco budworm, Heliothis virescens (F.), represents a problem in Texas and several other cotton production areas in the United States. To test for resistance, a technique was developed in which tobacco bud worm first instars were exposed to insecticide residues in 20-ml glass vials. Bioassays demonstrated resistance to cypermethrin and fenvalerate in all pyrethroid-resistant strains; low or no tolerance to the organophosphates profenofos, acephate, and methyl parathion; and resistance to the oxime carbamate thiodicarb in one resistant strain. Chlordimeform synergized all insecticides tested, even though the synergism was variable for different insecticides against different strains. Cypermethrin combined with chlordimeform was usually as toxic to resistant larvae as cypermethrin alone to susceptible larvae. The organophosphates (alone or combined with chlordimeform), the carbamate thiodicarb plus chlordimeform, and cypermethrin plus thiodicarb plus chlordimeform are possible alternate toxicants for control of resistant tobacco bud worm. Differences in tolerance to cypermethrin observed for resistant males and first instars showed that resistance mechanisms are not manifested equally in all developmental stages of tobacco budworm. Data on resistance gene frequency based on bioassays with cypermethrin conducted with males collected season-long in the Brazos Valley...

‣ Widespread pyrethroid resistance in Australian diamondback moth, Plutella xylostella (L.), is related to multiple mutations in the para sodium channel gene

Endersby, N.; Viduka, K.; Baxter, S.; Saw, J.; Heckel, D.; McKechnie, S.
Fonte: C A B I Publishing Publicador: C A B I Publishing
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
37.43417%
Populations of Plutella xylostella, extending over 3800 km in southern Australia, show no genetic structure as assessed by microsatellite markers; yet outbreaks of pyrethroid resistance occur sporadically in cropping areas. Since mutations in the para voltage-gated sodium channel gene have been implicated in pyrethroid resistance, we looked for DNA sequence variation at this target among Australian moths. We found two resistance mutations previously reported for this species (L1014F and T929I), as well as a novel substitution (F1020S). Of the eight possible haplotypes formed by combinations of these three biallelic polymorphisms, only four were found in Australian populations: the wild-type allele (w), the kdr mutation allele (kdr) with only L1014F, the super-kdr-like combination of L1014F and T929I (skdrl), and the crashdown allele with only F1020S (cdr). Comparison of genotype frequencies among survivors of permethrin assays with those from untreated controls identified three resistant genotypes: skdrl homozygotes, cdr homozygotes and the corresponding heterozygote, cdr/skrdl – the heterozygote being at least as resistant as either homozygote. Spatial heterogeneity of allele frequencies was conspicuous, both across the continent and among local collections...

‣ Analysing deltamethrin susceptibility and pyrethroid esterase activity variations in sylvatic and domestic Triatoma infestans at the embryonic stage

Santo Orihuela, Pablo Luis; Carvajal, Guillermo; Picollo, María Inés; Vassena, Claudia Viviana
Fonte: Fundacao Oswaldo Cruz Publicador: Fundacao Oswaldo Cruz
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Português
Relevância na Pesquisa
37.43417%
The aim of the present work was to study the deltamethrin susceptibility of eggs from populations of Triatoma infestans and contribution of pyrethroid esterases to its degradation. Insects were from sylvatic areas Veinte de Octubre and Kirus-Mayu (Bolivia) and from domiciliary areas El Palmar (Bolivia) and La Pista (Argentina). Susceptibility was determined by dose-response bioassays. Serial dilutions of deltamethrin (0.0005 to 1 mg/ml) were topically applied on 12 days old eggs. El Palmar showed the highest Lethal Doses Ratio (LDR) value (44.90) compared with NFS reference strain whereas Veinte de Octubre showed the lowest value (0.50). Pyrethroid esterases were evaluated using 7-coumaryl permethrate (7-CP) on individually homogenized eggs of each population and NFS. El Palmar and La Pista showed values of 40.11 and 36.64 pmol/min/mg protein, 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). The toxicological data indicate that the domestic populations are resistant to deltamethrin but no statistical contribution of 7-CP esterases was observed. Sylvatic populations showed values of LDR similar to NFS but lower activities of 7-CP esterases. This is the first study of pyrethroid esterases on eggs of Triatoma infestans using a specific substrate (7-CP).; Fil: Santo Orihuela...

‣ Contribution of general esterases to pyrethroid resistant Triatoma infestans (Hemiptera: Reduviidae) from Argentina and Bolivia

Santo-Orihuela,Pablo Luis; Picollo,María Inés
Fonte: Acta toxicológica argentina Publicador: Acta toxicológica argentina
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2011 Português
Relevância na Pesquisa
37.246926%
The objective of this work was the study of the relative contribution of general esterases: á-napthyl acetate (á-NA) and p-nitro phenyl acetate (p-NPA) in pyrethroid-resistant T. infestans from these locations. We used deltamethrin-resistant populations previously collected in two areas in Argentina (Salta and La Rioja) and one area in Bolivia (Tarija). In this study, frequency histograms of á-NA and p-NPA esterase activities, exhibited similar patterns between Bolivian population and the susceptible counterpart. In contrast, Argentinean field populations showed higher proportion of increased enzyme activity individuals. These results clearly demonstrated that resistances in Argentinean and Bolivian field populations are based on different mechanisms, suggesting that enzyme-based pyrethroid resistance in this species has multiple origins.

‣ Pyrethroid resistance in a major African malaria vector Anopheles arabiensis from Mamfene, northern KwaZulu-Natal, South Africa

Mouatcho,J.C.; Munhenga,G.; Hargreaves,K.; Brooke,B.D.; Coetzee,M.; Koekemoer,L.L.
Fonte: South African Journal of Science Publicador: South African Journal of Science
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2009 Português
Relevância na Pesquisa
37.08643%
A population of Anopheles arabiensis, a major malaria vector in South Africa, was collected during 2005 from inside sprayed houses in Mamfene, northern KwaZulu-Natal, South Africa, using window exit traps. None of these specimens (n = 300 females) was found to be infected with Plasmodium falciparum. Insecticide susceptibility assays on 2-3 day old F1 progeny using WHO susceptibility kits revealed 100% susceptibility to bendiocarb, resistance to deltamethrin (95.91%) was suspected, while resistance to permethrin (78.05%) was confirmed. The knockdown resistant (kdr) genotype was not found in the surviving mosquitoes. Biochemical analysis using enzyme assays showed elevated levels of monooxygenase that correlated with the permethrin bioassay data. While elevated levels of non-specific esterase were found in some families (11/12 for α- and 6/12 for β-esterases), the data did not show any correlation with the permethrin bioassay. Analysis of permethrin and bendiocarb tolerant lines, selected in the laboratory to characterise biochemical resistance profiles, showed increased levels of non-specific esterase and monooxygenase activity in the case of the permethrin-selected cohorts, and elevated glutathione S-transferases and general esterases in that of the bendiocarb-selected line. Synergist assays...