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Deep sequencing of New World screw-worm transcripts to discover genes involved in insecticide resistance

CARVALHO, Renato A.; AZEREDO-ESPIN, Ana Maria L.; TORRES, Tatiana T.
Fonte: BIOMED CENTRAL LTD Publicador: BIOMED CENTRAL LTD
Tipo: Artigo de Revista Científica
ENG
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Background: The New World screw-worm (NWS), Cochliomyia hominivorax, is one of the most important myiasis-causing flies, causing severe losses to the livestock industry. In its current geographical distribution, this species has been controlled by the application of insecticides, mainly organophosphate (OP) compounds, but a number of lineages have been identified that are resistant to such chemicals. Despite its economic importance, only limited genetic information is available for the NWS. Here, as a part of an effort to characterize the C. hominivorax genome and identify putative genes involved in insecticide resistance, we sampled its transcriptome by deep sequencing of polyadenylated transcripts using the 454 sequencing technology. Results: Deep sequencing on the 454 platform of three normalized libraries (larval, adult male and adult female) generated a total of 548,940 reads. Eighteen candidate genes coding for three metabolic detoxification enzyme families, cytochrome P450 monooxygenases, glutathione S transferases and carboxyl/cholinesterases were selected and gene expression levels were measured using quantitative real-time polymerase chain reaction (qRT-PCR). Of the investigated candidates, only one gene was expressed differently between control and resistant larvae with...

Microarray analysis of cytochrome P450 mediated insecticide resistance in Drosophila

Le Goff, G.; Boundy, S.; Daborn, P. J.; Yen, J. L.; Sofer, L.; Lind, R.; Sabourault, C.; Madi-Ravazzi, L.; ffrench-Constant, R. H.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 701-708
ENG
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Insecticide resistance in laboratory selected Drosophila strains has been associated with upregulation of a range of different cytochrome P450s, however in recent field isolates of D. melanogaster resistance to DDT and other compounds is conferred by one P450 gene, Cyp6g1. Using microarray analysis of all Drosophila P450 genes, here we show that different P450 genes such as Cyp12d1 and Cyp6a8 can also be selected using DDT in the laboratory. We also show, however, that a homolog of Cyp6g1 is over-expressed in a field resistant strain of D. simulans. In order to determine why Cyp6g1 is so widely selected in the field we examine the pattern of cross-resistance of both resistant strains and transgenic flies over-expressing Cyp6g1 alone. We show that all three DDT selected P450s can confer resistance to the neonicotinoid imidacloprid but that Cyp6a8 confers no cross-resistance to malathion. Transgenic flies over-expressing Cyp6g1 also show cross-resistance to other neonicotinoids such as acetamiprid and nitenpyram. We suggest that the broad level of cross-resistance shown by Cyp6g1 may have facilitated its selection as a resistance gene in natural Drosophila populations. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

Impact of insecticide resistance on the field control of Aedes aegypti in the State of São Paulo

Macoris, Maria De Lourdes Da Graça; Andrighetti, Maria Teresa Macoris; Wanderley, Dalva Marli Valério; Ribolla, Paulo Eduardo Martins
Fonte: Sociedade Brasileira de Medicina Tropical - SBMT Publicador: Sociedade Brasileira de Medicina Tropical - SBMT
Tipo: Artigo de Revista Científica Formato: 573-578
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Introduction The need to control dengue transmission by means of insecticides has led to the development of resistance to most of the products used worldwide against mosquitoes. In the State of São Paulo, the Superintendência de Controle de Endemias (SUCEN) has annually monitored the susceptibility of Aedes aegypti to insecticides since 1996; since 1999, surveys were conducted in collaboration with the National Network of Laboratories (MoReNAa Network) and were coordinated by the Ministry of Health. In this study, in addition to the biological characterization of insecticide resistance in the laboratory, the impact of resistance on field control was evaluated for vector populations that showed resistance in laboratory assays. Methods Field efficacy tests with larvicides and adulticides were performed over a 13-year period, using World Health Organization protocols. Results Data from the field tests showed a reduction in the residual effect of temephos on populations with a resistance ratio of 3. For adults, field control was less effective in populations characterized as resistant in laboratory qualitative assays...

Impact of insecticide resistance on the field control of Aedes aegypti in the State of São Paulo

Macoris,Maria de Lourdes da Graça; Andrighetti,Maria Teresa Macoris; Wanderley,Dalva Marli Valério; Ribolla,Paulo Eduardo Martins
Fonte: Sociedade Brasileira de Medicina Tropical - SBMT Publicador: Sociedade Brasileira de Medicina Tropical - SBMT
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2014 EN
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Introduction The need to control dengue transmission by means of insecticides has led to the development of resistance to most of the products used worldwide against mosquitoes. In the State of São Paulo, the Superintendência de Controle de Endemias (SUCEN) has annually monitored the susceptibility of Aedes aegypti to insecticides since 1996; since 1999, surveys were conducted in collaboration with the National Network of Laboratories (MoReNAa Network) and were coordinated by the Ministry of Health. In this study, in addition to the biological characterization of insecticide resistance in the laboratory, the impact of resistance on field control was evaluated for vector populations that showed resistance in laboratory assays. Methods Field efficacy tests with larvicides and adulticides were performed over a 13-year period, using World Health Organization protocols. Results Data from the field tests showed a reduction in the residual effect of temephos on populations with a resistance ratio of 3. For adults, field control was less effective in populations characterized as resistant in laboratory qualitative assays, and this was confirmed using qualitative assays and field evaluation. Conclusions Our results indicated that management of resistance development needs to be adopted when insect populations show reduced susceptibility. The use of insecticides is a self-limiting tool that needs to be applied cautiously...

Evaluation of Insecticide Resistance and Biochemical Mechanisms in a Population of Culex quinquefasciatus (Diptera: Culicidae) from São Paulo, Brazil

Bracco,José Eduardo; Barata,José Maria S; Marinotti,Osvaldo
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/1999 EN
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To establish an insecticidal resistance surveillance program, Culex quinquefasciatus mosquitoes from São Paulo, Brazil, were colonized (PIN95 strain) and analyzed for levels of resistance. The PIN95 strain showed low levels of resistance to organophosphates [malathion (3.3-fold), fenitrothion (11.2-fold)] and a carbamate [propoxur (3.0-fold)]. We also observed an increase of 7.4 and 9.9 in a and b esterase activities, respectively, when compared with the reference IAL strain. An alteration in the sensitivity of acetylcholinesterase to insecticide inhibition was also found in the PIN95 mosquitoes. The resistant allele (Ace.1R), however, was found at low frequencies (0.12) and does not play an important role in the described insecticide resistance. One year later, Cx. quinquefasciatus mosquitoes were collected (PIN96 strain) at the same site and compared to the PIN95 strain. The esterase activity patterns observed for the PIN96 strain were similar to those of the PIN95 mosquitoes. However the occurrence of the Ace.1R allele was statistically higher in the PIN96 strain. The results show that esterase-based insecticide resistance was established in the PIN95 Cx. quinquefasciatus population and that an acethylcholinesterase based resistant mechanism has been selected for. A continuous monitoring of this phenomenon is fundamental for rational mosquito control and insecticide application programs.

Genetic divergence between two sympatric species of the Lutzomyia longipalpis complex in the paralytic gene, a locus associated with insecticide resistance and lovesong production

Lins,RMMA; Souza,NA; Peixoto,AA
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2008 EN
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The sandfly Lutzomyia longipalpis s.l. is the main vector of American Visceral Leishmaniasis. L. longipalpis s.l. is a species complex but until recently the existence of cryptic sibling species among Brazilian populations was a controversial issue. A fragment of paralytic (para), a voltage dependent sodium channel gene associated with insecticide resistance and courtship song production in Drosophila, was isolated and used as a molecular marker to study the divergence between two sympatric siblings of the L. longipalpis complex from Sobral, Brazil. The results revealed para as the first single locus DNA marker presenting fixed differences between the two species in this locality. In addition, two low frequency amino-acid changes in an otherwise very conserved region of the channel were observed, raising the possibility that it might be associated with incipient resistance in this vector. To the best of our knowledge, the present study represents the first population genetics analysis of insecticide resistance genes in this important leishmaniasis vector.

The classification of esterases: an important gene family involved in insecticide resistance - A review

Montella,Isabela Reis; Schama,Renata; 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 01/06/2012 EN
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The use of chemical insecticides continues to play a major role in the control of disease vector populations, which is leading to the global dissemination of insecticide resistance. A greater capacity to detoxify insecticides, due to an increase in the expression or activity of three major enzyme families, also known as metabolic resistance, is one major resistance mechanisms. The esterase family of enzymes hydrolyse ester bonds, which are present in a wide range of insecticides; therefore, these enzymes may be involved in resistance to the main chemicals employed in control programs. Historically, insecticide resistance has driven research on insect esterases and schemes for their classification. Currently, several different nomenclatures are used to describe the esterases of distinct species and a universal standard classification does not exist. The esterase gene family appears to be rapidly evolving and each insect species has a unique complement of detoxification genes with only a few orthologues across species. The examples listed in this review cover different aspects of their biochemical nature. However, they do not appear to contribute to reliably distinguish among the different resistance mechanisms. Presently, the phylogenetic criterion appears to be the best one for esterase classification. Joint genomic...

Insecticide Resistance Status of Colorado Potato Beetle (Coleoptera: Chrysomelidae) Adults in Northern Xinjiang Uygur Autonomous Region

Jiang, Wei-Hua; Wang, Zhi-Tian; Xiong, Man-Hui; Lu, Wei-Ping; Liu, Ping; Guo, Wen-Chao; Li, Guo-Qing
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), has become the economically most important insect defoliator of potatoes, Solanum tuberosum L., in northern Xinjiang Uygur autonomous region in China. Currently, control of Colorado potato beetle relies mainly on chemical insecticides. And this may result in insecticide resistance. In this study, LD50 values were measured by a topical bioassay for 14 conventional insecticides in seven local populations from Urumqi, Changji, Tacheng, Nilka, Gongliu, Qapqal, and Tekes counties (cities). The Tekes field population was the most susceptible population and was selected as a reference strain. Compared with the Tekes strain, the Changji, Qapqal, Nilka, Tacheng, and Gongliu populations exhibited moderate to very high levels of resistance to cyhalothrin. The Qapqal and Changji populations showed a moderate and a very high resistance to deltamethrin, respectively. And the Changji population developed a high resistance against α-cypermethrin. Moreover, the Qapqal population had a moderate resistance to carbofuran, and the Urumqi population reached high level of resistance to endosulfan. Possible resistance mechanisms of the Changji and Qapqal populations were determined using three enzyme inhibitors. Triphenyl phosphate (TPP)...

Life-Stage Variation in Insecticide Resistance of the Western Flower Thrips (Thysanoptera: Thripidae)

Contreras, J.; Espinosa, P. J.; uinto, V.; Abellán, J.; Grávalos, C.; Fernández, E.; Bielza, P.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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The life-stage variations in insecticide resistance of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), to selective insecticides (acrinathrin, formetanate, and methiocarb) were studied using resistant laboratory strains. In each strain, the second-instar larva was less susceptible to the insecticides tested than the adults. The lower the resistance level of the adults, the higher the difference between larva and adult susceptibility: 32-fold to methiocarb, 15.4-fold to formetanate, and 180-fold to acrinathrin in the reference strain. In laboratory-selected resistant strains, these differences were much lower: 5.8-fold to methiocarb, 4.8-fold to formetanate, and 2.0-fold to acrinathrin. In selected strains, higher resistance levels for each insecticide were found, both for larvae and adults, compared with the reference strain. These results show that after insecticide resistance selection in adults, the resistance is carried over to the larvae, but at lower levels.

Preventive Insecticide Resistance Strategy in Helicoverpa (Heliothis) armigera (Lepidoptera: Noctuidae) in Israeli Cotton

Horowitz, A. R.; Seligman, M.; Forer, G.; Bar, D.; Ishaaya, I.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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Since 1987 an insecticide resistance management (IRM) strategy has been implemented in cotton fields in Israel. To assess the efficacy of the IRM strategy, a long-term monitoring program in Helicoverpa armigera (Hübner) was undertaken to test the response of this pest to various insecticides. The monitoring technique was based on the exposure of pheromone trap-caught males to residues of four common compounds representing the major groups of insecticides. The diagnostic concentrations, established on LC80-90 of a susceptible H. armigera field population, were 0.57 µg endosulfan, 0.74 µg cypermethrin, 0.38 µg methomyl, and 2.0 µg methidathion per scintillation vials. Collections of H. armigera moths were done during the cotton growing seasons of 1987 through 1991. In general, the results indicate that the susceptibility of H. armigera to the test compounds was not appreciably altered from 1987 to 1991, although fluctuations during the season were observed. In most cases, the resistance levels to the test compounds fluctuated in a typical V-shaped curve during the season. The susceptibility of H. armigera to the various insecticides observed during the course of this study is consistent with the proposition that the IRM strategy can be correlated with successfull management of resistance in this pest.

Economic Effects of Resistance and Withdrawal of Organophosphate Pesticides on an Apple Production System

Kazmierczak, Richaed F.; Norton, George W.; Knight, Alan L.; Rajotte, Edwin G.; Hull, Larry A.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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Theoretical investigations have suggested that resistance may have severe effects on the long-run economic performance of agricultural production systems. In addition, regulatory withdrawals of critical insecticides may hasten the development of resistance. Given the complexity of the problem, an optimizable bioeconomic simulation was used to examine the economic effects associated with regulation and insecticide resistance in the mid-Atlantic apple production system. Withdrawals of single organophosphates were modeled by reducing the size of a hypothetically complete insecticide control set. Reductions in the size of the insecticide control set led to substantial additional economic losses because of long-term resistance development. Azinphosmethyl withdrawal resulted in an additional -$1.66 billion present value loss and chlorpyrifos withdrawal an additional -$1.91 billion present value loss in economic benefits over a 25-yr period of analysis, whereas a withdrawal of microencapsulated methyl parathion resulted in an additional -$2.47 billion present value loss to resistance over 25 yr. Along with economic effects, insecticide withdrawals also led to changes in the total long-run use of chemical controls, although the magnitude and direction of the change depended on the specific insecticide withdrawn. Overall...

Monitoring and Characterization of Insecticide Resistance Codling Moth (Lepidoptera: Tortricidae) in Four Western States

Varela, L. G.; Welter, S. C.; Jones, V. P.; Brunner, J. F.; Riedl, H.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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Variation in response to insecticide in codling moth, Cydia pomonella (L.), was surveyed in California, Oregon, Utah, and Washington. Two techniques (topical application and direct incorporation of insecticide into the trap adhesive) were used to assay male moths caught in pheromone traps. Using the LC75 from a susceptible population as a standard dose, we monitored 20 apple and pear orchards for resistance to azinphosmethyl by the topical application technique. Orchards in California had the greatest interpopulation variability in resistance levels. In a single pear orchard in the Sacramento Delta, the level of resistance at the LC50 was ≈6.2 and 7.2 times greater than in a susceptible population when bioassays were done by topical application and adhesives were mixed with insecticide, respectively. Residual bioassays with neonate larvae collected from this site indicated 4.6-fold resistance. Orchards in Oregon showed little variability, and all populations appeared to be susceptible. Populations from Utah orchards showed little variability in the bioassay and were the most susceptible in the four states tested. Populations collected from Washington orchards had the highest tolerance levels. In laboratory tests...

Insecticide Resistance of Diamondback Moth (Lepidoptera: Plutellidae) in North America

Shelton, A. M.; Wyman, J. A.; Cushing, N. L.; Apfelbeck, K.; Dennehy, T. J.; Mahr, S. E. R.; Eigenbrode, S. D.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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Following widespread reports of control failures of the diamondback moth, Plutella xylostella (L.), in North America during 1987, a cooperative project was established in 1988-1989 in which 41 populations from 19 states within the United States, Mexico, Canada, and Belize were evaluated for resistance to three commonly used insecticides representing three major classes of insecticides (pyrethroids, carbamates, and organophosphates). The extent and geographic distribution of resistance to methomyl, permethrin, and methamidophos in North American populations was determined as a first step in developing resistance management strategies. Widespread resistance was confirmed to all three insecticides. Resistance was generally highest in populations that originated from the southern states (Texas, Florida, Georgia, and North Carolina), but scattered populations with high levels of resistance also were detected in northern states (New York, New Hampshire, New Jersey, Ohio, Indiana, Michigan, and Wisconsin). Highest levels of resistance were detected for methomyl, intermediate levels were detected to permethrin, and methamidophos had the lowest levels of resistance. For each population we observed a significant relationship between the log of the LC50 of one insecticide to that of another. Such significant relationships may be the result of cross-resistance between these classes of insecticides or simply may be the result of sequential development of resistance to each insecticide. Where data were available for field performance and laboratory bioassays on populations from certain regions...

Cytochrome P450 MA Expression in Insecticide-Resistant German Cockroaches (Dictyoptera: Blattellidae)

Scharf, Michael E.; Lee, Chow-Yang; Neal, Jonathan J.; Bennett, Gary W.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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Cytochrome P450 monooxygenases are detoxification enzymes commonly involved in insecticide resistance by insects. Recently, an overexpressed form of this enzyme, P450 MA, was purified from an insecticide-resistant strain of German cockroach, Blattella germanica (L.), and polyclonal antisera (anti-P450 MA) was produced. To test hypotheses that the overexpressed condition of P450 MA has evolved in >1 geographic location and that P450 MA might be involved in insecticide resistance to specific insecticides, investigations were conducted using 4 insecticide-resistant and 1 susceptible German cockroach strains. In western blots that used anti-P450 MA antiserum as a probe, substantial differences in expression of P450 MA were observed. Strains showing the highest P450 MA expression had both the highest tolerance to the organophosphate insecticide chlorpyrifos and cytochrome P450-mediated demethylation activity. Results support the hypothesis that cytochrome P450 MA is potentially overexpressed in insecticide-resistant populations on a global scale.

Greenbug Resistance Management on Sorghum with Insecticide Mixtures: a Biological and Economic Analysis

Archer, T. L.; Segarra, Eduardo; Bynum, E. D.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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Several tactics were evaluated for insecticide resistant greenbug, Schizaphis graminum (Rondani), control on sorghum. During the first 2 yr of this research, control by chlorpyrifos, carbofuran, and malathion and mixtures of the latter 2 chemicals plus piperonyl butoxide with chlorpyrifos were compared on sorghum. Chlorpyrifos provided <60% control. The mixtures of chlorpyrifos + carbofuran or malathion provided good control of insecticide resistant greenbug. The mixture of chlorpyrifos + piperonyl butoxide provided mediocre control of resistant greenbugs. In 1996, an experiment was designed to evaluate the effects of greenbug population insecticide resistance ratio and preexposure of greenbugs to chlorpyrifos on control by mixtures of chlorpyrifos with carbofuran or malathion. About half of the plots were presprayed with chlorpyrifos (0.28 kg [AI]/ha) 4 d before applying individual insecticides or mixtures. Plots were infested with 2 ratios of resistant: susceptible greenbugs (1:3 and 3:1, respectively). Application of mixtures of chlorpyrifos + malathion provided best control followed by chlorpyrifos + carbofuran and chlorpyrifos. Prespraying greenbugs with chlorpyrifos did not affect their control with subsequent insecticide resistance management mixtures. The difference between the 2 ratios was significant with the lowest greenbug densities in plots dominated by susceptible individuals. There was a significant yield response to greenbug densities. The highest yields were obtained in plots sprayed with chlorpyrifos + malathion mixtures. When chlorpyrifos was applied to greenbug populations dominated by resistant aphids...

History of insecticide resistance of Triatominae vectors

Pessoa,Grasielle Caldas Dávila; Vinãs,Pedro Albajar; Rosa,Aline Cristine Luiz; Diotaiuti,Liléia
Fonte: Sociedade Brasileira de Medicina Tropical - SBMT Publicador: Sociedade Brasileira de Medicina Tropical - SBMT
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2015 EN
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AbstractIn the last 15 years, different types of Triatominae resistance to different insecticides have been reported; thus, resistance may be more widespread than known, requiring better characterization and delimitation, which was the aim of this review. This review was structured on a literature search of all articles from 1970 to 2015 in the PubMed database that contained the keywords Insecticide resistance and Triatominae . Out of 295 articles screened by title, 33 texts were selected for detailed analysis. Insecticide resistance of Triatomines is a complex phenomenon that has been primarily reported in Argentina and Bolivia, and is caused by different factors (associated or isolated). Insecticide resistance of Triatominae is a characteristic inherited in an autosomal and semi-dominant manner, and is polygenic, being present in both domestic and sylvatic populations. The toxicological profile observed in eggs cannot be transposed to different stages of evolution. Different toxicological profiles exist at macro- and microgeographical levels. The insecticide phenotype has both reproductive and developmental costs. Different physiological mechanisms are involved in resistance. Studies of Triatomine resistance to insecticides highlight three deficiencies in interpreting the obtained results: I) the vast diversity of methodologies...

Pinpointing P450s associated with pyrethroid metabolism in the dengue vector, Aedes aegypti: developing new tools to combat insecticide resistance

Stevenson, Bradley J.; Pignatelli, Patricia; Nikou, Dimitra; Paine, Mark J. I.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 8 pages
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BACKGROUND Pyrethroids are increasingly used to block the transmission of diseases spread by Aedes aegypti such as dengue and yellow fever. However, insecticide resistance poses a serious threat, thus there is an urgent need to identify the genes and proteins associated with pyrethroid resistance in order to produce effective counter measures. In Ae. aegypti, overexpression of P450s such as the CYP9J32 gene have been linked with pyrethroid resistance. Our aim was to confirm the role of CYP9J32 and other P450s in insecticide metabolism in order to identify potential diagnostic resistance markers. METHODOLOGY/PRINCIPAL FINDINGS We have expressed CYP9J32 in Escherichia coli and show that the enzyme can metabolize the pyrethroids permethrin and deltamethrin. In addition, three other Ae. aegypti P450s (CYP9J24, CYP9J26, CYP9J28) were found capable of pyrethroid metabolism, albeit with lower activity. Both Ae. aegypti and Anopheles gambiae P450s (CYP's 6M2, 6Z2, 6P3) were screened against fluorogenic and luminescent substrates to identify potential diagnostic probes for P450 activity. Luciferin-PPXE was preferentially metabolised by the three major pyrethroid metabolisers (CYP9J32, CYP6M2 and CYP6P3), identifying a potential diagnostic substrate for these P450s. CONCLUSIONS/SIGNIFICANCE P450s have been identified with the potential to confer pyrethroid resistance in Ae.aegypti. It is recommended that over expression of these enzymes should be monitored as indicators of resistance where pyrethroids are used.; The majority of work was funded by the Innovative Vector Control Consortium (www.IVCC.com). Travel funds were also supplied by The Royal Society...

Investigação da resistencia a inseticidas na mosca-da-bicheira Cochliomyia hominivorax (Diptera; Calliphoridae); Investigation of insecticide resistance in the New World Screwworm fly Cochliomyia hominivorax (Diptera; Calliphoridae)

Norma Machado da Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 01/10/2009 PT
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66.54%
Cochliomyia hominivorax é considerada uma importante praga por causar perdas econômicas para a pecuária na região Neotropical. Este ectoparasita tem sido controlado principalmente por inseticidas, entretanto, este método normalmente resulta na seleção de indivíduos resistentes. Nesta tese foram investigados mecanismos associados com resistência a inseticidas organofosforados e piretróides. Os resultados apresentados nesta tese estão divididos em dois artigos. No artigo 1 foram investigados dois mecanismos de resistência a piretróides, um conhecido como kdr (knockdown resistance), associado à mutações no canal de sódio, e a mutação W251S no gene da carboxilesterase E3, a qual têm sido associada à hidrólise de piretróides. Foram investigadas populações da atual distribuição geográfica de C. hominivorax através de PCR-RFLP. Para a mutação kdr (L1014F) nenhum indivíduo mutante foi encontrado. Entretanto, a mutação W251S foi encontrada em todas as populações, com as mais altas freqüências nas amostras da Venezuela (100%) e Colômbia (93.75%). Em algumas populações amostradas, apesar da freqüência do alelo mutante ter sido relativamente baixa, o número de indivíduos portadores de pelo menos um alelo mutante foi alto. No bioensaio com cipermetrina (piretróide tipo II)...

Multiple insecticide resistance in Aedes aegypti (Diptera: Culicidae) populations compromises the effectiveness of dengue vector control in French Guiana

Dusfour,Isabelle; Thalmensy,Véronique; Gaborit,Pascal; Issaly,Jean; Carinci,Romuald; Girod,Romain
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2011 EN
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66.41%
In French Guiana, pyrethroids and organophosphates have been used for many years against Aedes aegypti. We aimed to establish both the resistance level of Ae. aegypti and the ultra low volume spray efficacy to provide mosquito control services with practical information to implement vector control and resistance management. Resistance to deltamethrin and fenitrothion was observed. In addition, the profound loss of efficacy of AquaK'othrine® and the moderate loss of efficacy of Paluthion® 500 were recorded. Fenitrothion remained the most effective candidate for spatial application in French Guiana until its removal in December 2010. Further investigation of the mechanism of resistance to deltamethrin demonstrated the involvement of mixed-function oxidases and, to a lesser extent, of carboxylesterases. However, these observations alone cannot explain the level of insecticide resistance we observed during tube and cage tests.

Evolution of insecticide resistance in non-target black flies (Diptera: Simuliidae) from Argentina

Montagna,Cristina Mónica; Gauna,Lidia Ester; D'Angelo,Ana Pechen de; Anguiano,Olga Liliana
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 EN
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Black flies, a non-target species of the insecticides used in fruit production, represent a severe medical and veterinary problem. Large increases in the level of resistance to the pyrethroids fenvalerate (more than 355-fold) and deltamethrin (162-fold) and a small increase in resistance to the organophosphate azinphos methyl (2-fold) were observed between 1996-2008 in black fly larvae under insecticide pressure. Eventually, no change or a slight variation in insecticide resistance was followed by a subsequent increase in resistance. The evolution of pesticide resistance in a field population is a complex and stepwise process that is influenced by several factors, the most significant of which is the insecticide selection pressure, such as the dose and frequency of application. The variation in insecticide susceptibility within a black fly population in the productive area may be related to changes in fruit-pest control. The frequency of individuals with esterase activities higher than the maximum value determined in the susceptible population increased consistently over the sampling period. However, the insecticide resistance was not attributed to glutathione S-transferase activity. In conclusion, esterase activity in black flies from the productive area is one mechanism underlying the high levels of resistance to pyrethroids...