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2.
Insect Sci ; 27(2): 276-291, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30136378

RESUMO

Uridine diphosphate (UDP)-glycosyltransferases (UGTs) are widely distributed within living organisms and share roles in biotransformation of various lipophilic endo- and xenobiotics with activated UDP sugars. In this study, it was found that the activity of UGTs in abamectin-resistant (AbR) strain was significantly higher (2.35-fold) than that in susceptible strain (SS) of Tetranychus cinnabarinus. Further analysis showed that 5-nitrouracil, the inhibitor of UGTs, could enhance the lethal effect of abamectin on mites. From the previous microarray results, we found an UGT gene (UGT201D3) overexpressed in AbR strain. Quantitative PCR analysis showed that UGT201D3 was highly expressed and more inducible with abamectin exposure in the AbR strain. After silencing the transcription of UGT201D3, the activity of UGTs was decreased and the susceptibility to abamectin was increased in AbR strain whereas it was not in SS. Furthermore, UGT201D3 gene was then successfully expressed in Escherichia coli. The recombinant UGT201D3 exhibited α-naphthol activity (2.81 ± 0.43 nmol/mg protein/min), and the enzyme activity could be inhibited by abamectin (inhibitory concentration at 50%: 57.50 ± 3.54 µmol/L). High-performance liquid chromatography analysis demonstrated that the recombinant UGT201D3 could effectively deplete abamectin (15.77% ± 3.72%) incubating with 150 µg protein for 6 h. These results provided direct evidence that UGT201D3 was involved in abamectin resistance in T. cinnabarinus.


Assuntos
Glucuronosiltransferase/metabolismo , Inseticidas , Ivermectina/análogos & derivados , Tetranychidae/metabolismo , Sequência de Aminoácidos , Animais , Escherichia coli , Feminino , Glucuronosiltransferase/genética , Resistência a Inseticidas , Interferência de RNA , Tetranychidae/genética , Uracila/análogos & derivados
3.
Bull Entomol Res ; 110(1): 96-105, 2020 Feb.
Artigo em Italiano | MEDLINE | ID: mdl-31190656

RESUMO

Diamides have been used worldwide to manage the diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae), however some strains showed resistance to these molecules. Also, pheromone traps could be used to manage this pest, hence reducing the use of insecticides in the field. Resistant DBM strains may have biological disadvantages in comparison to susceptible strains in areas without sprays, including reduction in fitness or behavioral changes. Therefore, the aim of this study was to investigate whether DBM strains resistant to chlorantraniliprole showed adaptive costs that could alter male attraction to the sex pheromone, in comparison to susceptible strains in the laboratory and semi-field conditions. First, the LC1, LC10, LC25, and LC50 of DBM to chlorantraniliprole were established, which were 0.003, 0.005, 0.007, and 0.011 mg a.i. liter-1, and 5.88, 24.80, 57.22, and 144.87 mg a.i. liter-1 for the susceptible and resistant strains, respectively. Development and reproduction of DBM strains subjected to those concentrations were compared. Later, male response to the sex pheromone was investigated in a Y-tube in the laboratory and in a greenhouse to pheromone traps. Resistant DBM strain showed an adaptive cost in comparison to the susceptible strain that can result in a delay in population growth in the field when selection pressure is absent. Conversely, resistant males have no olfactory response alteration in comparison to susceptible males, consistently at 3 (P = 0.6848) and 7 days (P = 0.9140) after release, suggesting that pheromone traps continue to be a viable alternative to manage DBM in an IPM system.


Assuntos
Adaptação Biológica , Inseticidas , Mariposas/fisiologia , Comportamento Sexual Animal/fisiologia , ortoaminobenzoatos , Animais , Resistência a Inseticidas/fisiologia , Masculino , Atrativos Sexuais , Olfato
4.
Bull Entomol Res ; 110(1): 57-67, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31217039

RESUMO

Glyphodes pyloalis Walker (Lepidoptera: Pyralididae) is a common pest in sericulture and has developed resistance to different insecticides. However, the mechanisms involved in insecticide resistance of G. pyloalis are poorly understood. Here, we present the first whole-transcriptome analysis of differential expression genes in insecticide-resistant and susceptible G. pyloalis. Clustering and enrichment analysis of DEGs revealed several biological pathways and enriched Gene Ontology terms were related to detoxification or insecticide resistance. Genes involved in insecticide metabolic processes, including cytochrome P450, glutathione S-transferases and carboxylesterase, were identified in the larval midgut of G. pyloalis. Among them, CYP324A19, CYP304F17, CYP6AW1, CYP6AB10, GSTs5, and AChE-like were significantly increased after propoxur treatment, while CYP324A19, CCE001c, and AChE-like were significantly induced by phoxim, suggesting that these genes were involved in insecticide metabolism. Furthermore, the sequence variation analysis identified 21 single nucleotide polymorphisms within CYP9A20, CYP6AB47, and CYP6AW1. Our findings reveal many candidate genes related to insecticide resistance of G. pyloalis. These results provide novel insights into insecticide resistance and facilitate the development of insecticides with greater specificity to G. pyloalis.


Assuntos
Inativação Metabólica/genética , Resistência a Inseticidas/genética , Mariposas/metabolismo , Animais , Sistema Enzimático do Citocromo P-450/genética , Feminino , Perfilação da Expressão Gênica , Genes de Insetos , Masculino , Mariposas/genética , Polimorfismo de Nucleotídeo Único , Transcriptoma
5.
Vet Parasitol ; 277: 109011, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31841946

RESUMO

In the present study, the tick isolates were collected from Assam state, of northeastern region (NER) and characterized using in vitro bioassay, biochemical and molecular assays. Comparing LC50 value of susceptible IVRI-I and larvae of field isolates, revealed that RF against deltamethrin was highest for Morigaon (MGN = 21.8) and lowest for Sonitpur (SNP = 3.3) isolate. The RF against cypermethrin was highest for Nagaon (NGO = 5.0) and lowest for Barpeta (BPT = 1.2) isolate. Against coumaphos, the highest RF of 4.5 was calculated for BPT (4.5) and lowest for NGO (1.3) isolate. While using adults based assay, highest RF of 24.68 against deltamethrin and lowest RF of 4.96 was determined for MGN and SNP isolate, respectively. In contrast to the results obtained using larvae, against cypermethrin, highest RF was recorded for Kamrup Metropolitan (KMP) while it was NGO isolate using larvae. In case of coumaphos, both larvae and adults of BPT isolate were also highly resistant and lowest RF was detected in SNP (2.30) isolate. All the isolates were susceptible to ivermectin. A significant correlation (p < 0.01) between deltamethrin resistance and higher expression of glutathioneS-transferase was observed while no correlation with esterase and monooxygenase enzymes activity was noted. For the development of possible ecofriendly control measure, different accessions of Argemone mexicana and Datura metel plant species were collected, extracted and screened against adult ticks. Two accessions, NEA-03 and NED-06 collected from Amlighat and Diphu (East Karbi Anglong) were more than 90 % effective. Further dose response study of these accessions determined the LC50 values of 4.86 and 3.96 %, respectively.The resistance status of the collected tick isolates was compared with the data generated from other regions having higher livestock population and possibility of exploitation of identified plant species for the development of natural antitick product is discussed.


Assuntos
Acaricidas/farmacologia , Resistência a Inseticidas , Extratos Vegetais/farmacologia , Rhipicephalus/efeitos dos fármacos , Animais , Bovinos , Índia , Resistência a Inseticidas/efeitos dos fármacos , Dose Letal Mediana , Estágios do Ciclo de Vida/efeitos dos fármacos
6.
Ambio ; 49(1): 1-16, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30903512

RESUMO

Cooperative management of pest susceptibility to transgenic Bacillus thuringiensis (Bt) crops is pursued worldwide in a variety of forms and to varying degrees of success depending on context. We examine this context using a comparative socioecological analysis of resistance management in Australia, Brazil, India, and the United States. We find that a shared understanding of resistance risks among government regulators, growers, and other actors is critical for effective governance. Furthermore, monitoring of grower compliance with resistance management requirements, surveillance of resistance, and mechanisms to support rapid implementation of remedial actions are essential to achieve desirable outcomes. Mandated resistance management measures, strong coordination between actors, and direct linkages between the group that appraises resistance risks and growers also appear to enhance prospects for effective governance. Our analysis highlights factors that could improve current governance systems and inform other initiatives to conserve susceptibility as a contribution to the cause of public good.


Assuntos
Bacillus thuringiensis , Austrália , Brasil , Índia , Resistência a Inseticidas , Controle Biológico de Vetores , Plantas Geneticamente Modificadas , Estados Unidos
7.
J Insect Sci ; 19(6)2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31841603

RESUMO

Spodoptera frugiperda (J. E. Smith) is one of the major pests of maize in Argentina. The main tool for its control is the use of genetically modified maize hybrids expressing Bacillus thuringiensis (Bt) insecticidal proteins. Maize growers in Argentina initially controlled this pest with Bt maize that expressed a single Bt protein (Cry1Ab or Cry1F). Currently it is necessary to plant maize cultivars that produce two Bt proteins to achieve the satisfactory control. Recently, Cry1F field-evolved resistant populations of this species were confirmed in Argentina. The objective of this study was to evaluate the performance of S. frugiperda field-collected strains on different Bt and non-Bt maize hybrids. Strains were collected from non-Bt maize (T1), Agrisure TDMax (T2), Agrisure Viptera (T3), Agrisure Viptera 3110 (T4), Genuity VT Triple Pro (T5), and Power Core (T6). Three experiments were performed to 1) determine the survivorship and reproduction of field-collected larvae (F0) from Bt maize hybrids, 2) evaluate Cry1F resistance using an F1 screen, and 3) assess the performance of F1 strains on different maize hybrids. In the F0, the survivorship from larva to adult ranged from 0 to 63%. We obtained adults from only the T1, T2, T5, and T6 strains with no significant differences in the reproductive parameters. Continuously rearing F1 larvae on their collected hosts affected larval duration, which was significantly shorter for a known-laboratory Bt-susceptible strain than the field-collected strains. Our results support the existence of Cry1F-resistance alleles in S. frugiperda field populations in Argentina.


Assuntos
Proteínas de Bactérias , Endotoxinas , Proteínas Hemolisinas , Spodoptera , Animais , Feminino , Resistência a Inseticidas/genética , Masculino , Plantas Geneticamente Modificadas , Zea mays
8.
Parasit Vectors ; 12(1): 522, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31690332

RESUMO

BACKGROUND: Insecticides formulated into products that target Anopheles mosquitos have had an immense impact on reducing malaria cases in Africa. However, resistance to currently used insecticides is spreading rapidly and there is an urgent need for alternative public health insecticides. Potential new insecticides must be screened against a range of characterized mosquito strains to identify potential resistance liabilities. The Liverpool School of Tropical Medicine maintains three susceptible and four resistant Anopheles strains that are widely used for screening for new insecticides. The properties of these strains are described in this paper. METHODS: WHO tube susceptibility bioassays were used for colony selection and to screen for resistance to the major classes of public health insecticides. Topical and tarsal contact bioassays were used to produce dose response curves to assess resistance intensity. Bioassays with the synergist piperonyl butoxide were also performed. Taqman™ assays were used to screen for known target site resistance alleles (kdr and ace-1). RT-qPCR was used to quantify expression of genes associated with pyrethroid resistance. RESULTS: Pyrethroid selection pressure has maintained resistance to this class in all four resistant strains. Some carbamate and organophosphate resistance has been lost through lack of exposure to these insecticide classes. The Anopheles gambiae (sensu lato) strains, VK7 2014, Banfora M and Tiassalé 13 have higher levels of pyrethroid resistance than the An. funestus FUMOZ-R strain. Elevated expression of P450s is found in all four strains and the 1014F kdr mutation is present in all three An. gambiae strains at varying frequencies. Tarsal contact data and overexpression of CYP4G16 and SAP2 suggest penetration barriers and/or sequestration also confer resistance in Banfora M. CONCLUSIONS: Continual selection with deltamethrin has maintained a stable pyrethroid-resistant phenotype over many generations. In conjunction with a standardized rearing regime, this ensures quality control of strains over time allowing for robust product comparison and selection of optimal products for further development. The identification of multiple mechanisms underpinning insecticide resistance highlights the importance of screening new compounds against a range of mosquito strains.


Assuntos
Anopheles/classificação , Inseticidas , Malária/prevenção & controle , Controle de Mosquitos/métodos , Mosquitos Vetores/classificação , Análise de Variância , Animais , Anopheles/genética , Bioensaio , Sistema Enzimático do Citocromo P-450/análise , Sistema Enzimático do Citocromo P-450/genética , DNA/genética , DNA/isolamento & purificação , Relação Dose-Resposta a Droga , Feminino , Técnicas de Genotipagem , Resistência a Inseticidas , Malária/transmissão , Controle de Mosquitos/normas , Mosquitos Vetores/genética , Mutação Puntual , Piretrinas
9.
Rev Bras Parasitol Vet ; 28(4): 802-806, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31691737

RESUMO

Population explosions of the stable fly (Stomoxys calcitrans) have become a serious concern for livestock producers near sugarcane mills in some regions of Brazil due to the insect's massive reproduction on sugarcane byproducts and waste. Despite the limited efficiency of insecticides for controlling stable fly outbreaks, producers still rely on chemical control to mitigate the alarming infestations in affected areas. This study evaluated the susceptibility of S. calcitrans populations to cypermethrin in the state of Mato Grosso do Sul, Brazil. Stable flies were tested from three field populations and two colonies, established from flies previously collected at sugarcane mills. Wild flies were collected with Nzi traps in areas of sugarcane plantations. Both wild and colonized flies were exposed to eleven concentrations of cypermethrin in impregnated filter paper bioassays. All the populations proved to be resistant to cypermethrin, with resistance factors among field populations ranging from 6.8 to 38.6. The intensive use of insecticides has led to the development of pyrethroid resistance in stable fly populations in the proximities of sugarcane mills in the state of Mato Grosso do Sul.


Assuntos
Inseticidas/farmacologia , Muscidae/efeitos dos fármacos , Piretrinas/farmacologia , Animais , Bioensaio , Brasil , Resistência a Inseticidas , Dose Letal Mediana
10.
BMC Public Health ; 19(1): 1456, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31694595

RESUMO

BACKGROUND: Pesticides remain the mainstay for the control of agricultural pests and disease vectors. However, their indiscriminate use in agriculture has led to development of resistance to both crop pests and disease vectors. This threatens to undermine the success gained through the implementation of chemical based vector control programs. We investigated the practices of farmers with regard to pesticide usage in the vegetable growing areas and their impact on susceptibility status of An. gambiae s.l. METHODS: A stratified multistage sampling technique using the administrative structure of the Tanzanian districts as sampling frame was used. Wards, villages and then participants with farms where pesticides are applied were purposively recruited at different stages of the process, 100 participants were enrolled in the study. The same villages were used for mosquito larvae sampling from the farms and the surveys were complimented by the entomological study. Larvae were reared in the insectary and the emerging 2-3 days old female adults of Anopheles gambiae s.l were subjected to susceptibility test. RESULTS: Forty eight pesticides of different formulations were used for control of crop and Livestock pests. Pyrethroids were the mostly used class of pesticides (50%) while organophosphates and carbamates were of secondary importance. Over 80% of all farmers applied pesticides in mixed form. Susceptibility test results confirmed high phenotypic resistance among An. gambiae populations against DDT and the pyrethroids (Permethrin-0.75%, Cyfluthrin-0.15%, Deltametrin-0.05% and Lambdacyhalothrin-0.05%) with mortality rates 54, 61, 76 and 71%, respectively. Molecular analysis showed An. arabiensis as a dominant species (86%) while An. gambiae s.s constituted only 6%. The kdr genes were not detected in all of the specimens that survived insecticide exposures. CONCLUSION: The study found out that there is a common use of pyrethroids in farms, Livestocks as well as in public health. The study also reports high phenotypic resistance among An. gambiae s.l against most of the pyrethroids tested. The preponderance of pyrethroids in agriculture is of public health concern because this is the class of insecticides widely used in vector control programs and this calls for combined integrated pest and vector management (IPVM).


Assuntos
Agricultura/estatística & dados numéricos , Doenças Endêmicas/prevenção & controle , Resistência a Inseticidas , Inseticidas/farmacologia , Malária/prevenção & controle , Mosquitos Vetores/efeitos dos fármacos , Animais , Anopheles/efeitos dos fármacos , Fazendeiros/estatística & dados numéricos , Humanos , Larva/efeitos dos fármacos , Malária/epidemiologia , Tanzânia/epidemiologia
11.
Insect Biochem Mol Biol ; 115: 103247, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31626952

RESUMO

The diamondback moth, Plutella xylostella, is a damaging pest of cruciferous crops, and has evolved resistance to many of the insecticides used for control, including members of the diamide class. Previous work on the molecular basis of resistance to diamides has documented mutations in the target-site, the ryanodine receptor, in resistant populations of P. xylostella worldwide. In contrast the role of metabolic resistance to this insecticide class is significantly less clear. Here we show that overexpression of a flavin-dependent monooxgenase (FMO) confers resistance to the diamide chlorantraniliprole in P. xylostella. Transcriptome profiling of diamide resistant strains, with and without target-site resistance, revealed constitutive over-expression of several transcripts encoding detoxification enzymes compared to susceptible strains. Two of these, CYP6BG1, and PxFMO2 were particularly highly overexpressed (33,000 and 14,700-fold, respectively) in a resistant strain (HAW) lacking target-site resistance. After 17 generations without diamide selection the resistance of the HAW strain fell by 52-fold and the expression of PxFMO2 by > 1300-fold, however, the expression of CYP6BG1 declined by only 3-fold. Generation of transgenic Drosophila melanogaster expressing these genes demonstrated that PxFMO2, but not CYP6BG1, confers resistance in vivo. Overexpression of PxFMO2 in the HAW strain is associated with mutations, including a putative transposable element insertion, in the promoter of this gene. These enhance the expression of a reporter gene when expressed in a lepidopteran cell line suggesting they are, at least in part, responsible for the overexpression of PxFMO2 in the resistant strain. Our results provide new evidence that insect FMOs can be recruited to provide resistance to synthetic insecticides.


Assuntos
Família 6 do Citocromo P450/metabolismo , Inseticidas , Mariposas/enzimologia , Oxigenases/metabolismo , ortoaminobenzoatos , Animais , Feminino , Perfilação da Expressão Gênica , Inativação Metabólica , Resistência a Inseticidas , Masculino
12.
Malar J ; 18(1): 335, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31570107

RESUMO

BACKGROUND: The decline in malaria cases and vectors is major milestone in fighting against malaria. The efficacy of MAGNet long-lasting insecticidal nets (MAGNet LLIN), an alpha-cypermethrin incorporated long-lasting net, with the target dose ± 25% of 5.8 g active ingredient (AI)/kg (4.35-7.25 g AI/kg) was evaluated in six veranda-trap experimental huts in Muheza, Tanzania against freely flying wild population of Anopheles funestus. METHODS: MAGNet LLINs were tested against wild, free-flying, host-seeking An. funestus mosquitoes over a period of 6 weeks (total of 36 nights in the huts). MAGNet LLIN efficacy was determined in terms of mosquito mortality, blood-feeding inhibition, deterrence, induced exiting, personal protection, and insecticidal killing over 20 washes according to WHO standardized procedures. Efficacy was compared with reference to a WHOPES recommended approved LLINs (DuraNet) and to a net conventionally treated (CTN) treated with alpha-cypermethrin at WHO-recommended dose and washed to just before cut-off point. The efficacy of MAGNet was evaluated in experimental huts against wild, free-flying, pyrethroid-resistant An. funestus. The WHO-susceptibility method was used to detect resistance in wild Anopheles exposed to 0.75% permethrin. Mosquito mortality, blood-feeding inhibition and personal protection were compared between untreated nets and standard LLINs. Blood-feeding rates were recorded and compared between the 20 times washed; blood-feeding rates between 20 times washed MAGNet LLIN and 20 times washed WHOPES-approved piperonyl butoxide (PBO)/pyrethroid were not statistically different (p > 0.05). RESULTS: The results have evidently shown that MAGNet LLIN provides similar blood-feeding inhibition, exophily, mortality, and deterrence to the standard approved LLIN, thus meeting the WHOPES criteria for blood feeding. The significantly high feeding inhibition and personal protection over pyrethroid-resistant An. funestus recorded by both unwashed and 20 times washed MAGNet compared to the unwashed DuraNet, the WHOPES-approved standard pyrethroid-only LLIN provides proof of MAGNet meeting Phase II WHOPES criteria for a LLIN. CONCLUSION: Based on this study, MAGNet has been shown to have a promising impact on protection when 20 times washed against a highly resistant population of An. funestus.


Assuntos
Anopheles , Mosquiteiros Tratados com Inseticida , Inseticidas , Lavanderia , Piretrinas , Animais , Habitação , Resistência a Inseticidas , Controle de Mosquitos/instrumentação , Tanzânia
13.
J Econ Entomol ; 112(6): 2907-2914, 2019 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-31587050

RESUMO

Under ideal conditions, widely adopted transgenic crop pyramids producing two or more distinct insecticidal proteins from Bacillus thuringiensis (Bt) that kill the same pest can substantially delay evolution of resistance by pests. However, deviations from ideal conditions diminish the advantages of such pyramids. Here, we tested the hypothesis that changes in maturing cotton producing Cry1Ac and Cry2Ab affect evolution of resistance in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), a pest with low inherent susceptibility to both toxins. In terminal leaves of field-grown Bt cotton, the concentration of both toxins was significantly higher for young, squaring plants than for old, fruiting plants. We used laboratory bioassays with plant material from field-grown cotton to test H. zea larvae from a strain selected for resistance to Cry1Ac in the laboratory, its more susceptible parent strain, and their F1 progeny. On young Bt cotton, no individuals survived to pupation. On old Bt cotton, survival to pupation was significantly higher for the lab-selected strain and the F1 progeny relative to the unselected parent strain, indicating dominant inheritance of resistance. Redundant killing, the extent to which insects resistant to one toxin are killed by another toxin in a pyramid, was complete on young Bt cotton, but not on old Bt cotton. No significant fitness costs associated with resistance were detected on young or old non-Bt cotton. Incorporation of empirical data into simulations indicates the observed increased selection for resistance on old Bt cotton could accelerate evolution of resistance to cotton producing Cry1Ac and Cry2Ab in H. zea.


Assuntos
Bacillus thuringiensis , Mariposas , Animais , Proteínas de Bactérias , Endotoxinas , Gossypium , Proteínas Hemolisinas , Resistência a Inseticidas , Plantas Geneticamente Modificadas , Estações do Ano , Zea mays
14.
Arch Insect Biochem Physiol ; 102(3): e21621, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31538676

RESUMO

Diamondback moth, Plutella xylostella (L.), is a specialist pest on cruciferous crops of economic importance. The large-scale use of chemical insecticides for the control of this insect pest has caused a number of challenges to agro-ecosystems. With the advent of the omics era, genetic pest management strategies are becoming increasingly feasible and show a powerful potential for pest control. Here, we review strategies for using transgenic plants and sterile insect techniques for genetic pest management and introduce the major advances in the control of P. xylostella using a female-specific RIDL (release of insects carrying a dominant lethal gene) strategy. Further, the advantages of gene drive developed in combination with sex determination and CRISPR/Cas9 systems are addressed, and the corresponding prospects and implementation issues are discussed. It is predictable that under the policy and regulation of professional committees, the genetic pest control strategy, especially for gene drive, will open a new avenue to sustainable pest management not only for P. xylostella but also for other insect pests.


Assuntos
Controle de Insetos/métodos , Resistência a Inseticidas , Mariposas/genética , Animais , Animais Geneticamente Modificados , Sistemas CRISPR-Cas , Feminino , Plantas Geneticamente Modificadas
15.
Int Health ; 11(5): 341-343, 2019 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-31529112

RESUMO

Vector control is essential for the prevention and reduction of malaria transmission and is increasingly recognised as a key element of several neglected tropical disease (NTD) elimination programmes. Very few vector control interventions have a strong evidence base for their public health impact, and those that do are insecticide-based and threatened by resistance. The pipeline of new interventions and new insecticides is being filled and several are undergoing randomised controlled trials. If these are subsequently to be used sustainably, interventions will need to be combined. The major challenge will be to generate the evidence base and funding to achieve this sustainable combination at the country level. Unless this is done, the selection pressure for resistance to the new generation of vector control tools is likely to rapidly reduce our ability to control insect vectors in the foreseeable future.


Assuntos
Insetos Vetores , Malária/prevenção & controle , Controle de Mosquitos/métodos , Animais , Humanos , Insetos Vetores/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/administração & dosagem , Inseticidas/farmacologia , Ensaios Clínicos Controlados Aleatórios como Assunto
16.
PLoS Negl Trop Dis ; 13(9): e0007665, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31525199

RESUMO

Dengue is one of the most serious mosquito-borne infectious diseases in the world. Aedes albopictus is the most invasive mosquito and one of the primary vectors of dengue. Vector control using insecticides is the only viable strategy to prevent dengue virus transmission. In Guangzhou, after the 2014 pandemic, massive insecticides have been implemented. Massive insecticide use may lead to the development of resistance, but few reports are available on the status of insecticide resistance in Guangzhou after 2014. In this study, Ae. albopictus were collected from four districts with varied dengue virus transmission intensity in Guangzhou from 2015 to 2017. Adult Ae. albopictus insecticide susceptibility to deltamethrin (0.03%), permethrin(0.25%), DDT(4%), malathion (0.8%) and bendiocarb (0.1%) was determined by the standard WHO tube test, and larval resistance bioassays were conducted using temephos, Bacillus thuringiensis israelensis (Bti), pyriproxyfen (PPF) and hexaflumuron. Mutations at the voltage-gated sodium channel (VGSC) gene and acetylcholinesterase (AChE) gene were analyzed. The effect of cytochrome P450s on the resistance of Ae. albopictus to deltamethrin was tested using the synergistic agent piperonyl butoxide (PBO). The results showed that Ae. albopictus populations have rapidly developed very high resistances to multiple commonly used insecticides at all study areas except malathion, Bti and hexaflumuron. We found 1534 codon mutations in the VGSC gene that were significantly correlated with the resistance to pyrethroids and DDT, and 11 synonymous mutations were also found in the gene. The resistance to deltamethrin can be significantly reduced by PBO but may generated cross-resistance to PPF. Fast emerging resistance in Ae. albopictus may affect mosquito management and threaten the prevention and control of dengue, similar to the resistance in Anopheles mosquitoes has prevented the elimination of malaria and call for timely and guided insecticide management.


Assuntos
Aedes/genética , Resistência a Inseticidas , Inseticidas , Animais , China , Dengue/prevenção & controle , Dengue/transmissão , Larva/efeitos dos fármacos , Larva/genética , Controle de Mosquitos , Mosquitos Vetores , Mutação
17.
J Econ Entomol ; 112(6): 2915-2922, 2019 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-31504657

RESUMO

Striacosta albicosta (Smith) is a maize pest that has recently expanded its geographical range into the eastern United States and southeastern Canada. Aerial application of pyrethroids, such as bifenthrin, has been a major practice adopted to manage this pest. Reports of field failure of pyrethroids have increased since 2013. Striacosta albicosta populations were collected in 2016 and 2017 from maize fields in Nebraska, Kansas, and Canada and screened with bifenthrin active ingredient in larval contact dose-response bioassays. Resistance ratios estimated were generally low in 2016 (1.04- to 1.32-fold) with the highest LC50 in North Platte, NE (66.10 ng/cm2) and lowest in Scottsbluff, NE (50.10 ng/cm2). In 2017, O'Neill, NE showed the highest LC50 (100.66 ng/cm2) and Delhi, Canada exhibited the lowest (6.33 ng/cm2), resulting in a resistance ratio variation of 6.02- to 15.90-fold. Implications of bifenthrin resistance levels were further investigated by aerial application simulations. Experiments were conducted with a spray chamber where representative S. albicosta populations were exposed to labeled rates of a commercial bifenthrin formulation. Experiments resulted in 100% mortality for all populations, instars, insecticide rates, and carrier volumes, suggesting that levels of resistance estimated for bifenthrin active ingredient did not seem to impact the efficacy of the correspondent commercial product under controlled conditions. Results obtained from this research indicate that control failures reported in Nebraska could be associated with factors other than insecticide resistance, such as issues with the application technique, environmental conditions during and/or after application, or the insect's natural behavior. Data generated will assist future S. albicosta resistance management programs.


Assuntos
Inseticidas , Piretrinas , Animais , Canadá , Resistência a Inseticidas , Kansas , Nebraska
18.
Arch Insect Biochem Physiol ; 102(3): e21613, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31549439

RESUMO

Frankliniella occidentalis is an economically important invasive pest worldwide, which can damage various horticultural crops and ornamental plants. F. occidentalis was first intercepted in Kunming, Yunnan province in 2000, and first reported to establish a population in Beijing, China in 2003. Since then, this pest is currently distributed across tens of provinces in mainland China and cause increasingly serious damage and loss. To control this pest, invasion biology, monitoring, and integrated pest management have been generally and intensively studied for 15 years in China. Furthermore, western flower thrips (WFT) as an important invasive insect pest, the research achievements on WFT has contributed to the promotion of technological innovation and development for invasive alien species management strategies and techniques in China. This review provides an overview for research on the biology, ecology, prevention, and management of this pest during 15 years in China. Meanwhile, China's "4E action" strategy on F. occidentalis is also discussed in this review.


Assuntos
Controle de Insetos/métodos , Tisanópteros/fisiologia , Animais , China , Genética Populacional , Resistência a Inseticidas , Inseticidas , Espécies Introduzidas , Tisanópteros/genética
19.
Mem Inst Oswaldo Cruz ; 114: e190120, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31553370

RESUMO

BACKGROUND: In recent years, South America has suffered the burden of continuous high impact outbreaks of dengue, chikungunya and Zika. Aedes aegypti is the main mosquito vector of these arboviruses and its control is the only solution to reduce transmission. OBJECTIVES: In order to improve vector control it is essential to study mosquito population genetics in order to better estimate the population structures and the geneflow among them. METHODS: We have analysed microsatellites and knockdown resistance (kdr) mutations from a trans-border region in Amazonia between the state of Amapá (Brazil) and French Guiana (overseas territory of France), to provide further knowledge on these issues. These two countries have followed distinct vector control policies since last century. For population genetic analyses we evaluated variability in 13 well-established microsatellites loci in Ae. aegypti from French Guiana (Saint Georges and Cayenne) and Brazil (Oiapoque and Macapá). The occurrence and frequency of kdr mutations in these same populations were accessed by TaqMan genotype assays for the sites 1016 (Val/Ile) and 1534 (Phe/Cys). FINDINGS: We have detected high levels of gene flow between the closest cross-border samples of Saint-Georges and Oiapoque. These results suggest one common origin of re-colonisation for the populations of French Guiana and Oiapoque in Brazil, and a different source for Macapá, more similar to the other northern Brazilian populations. Genotyping of the kdr mutations revealed distinct patterns for Cayenne and Macapá associated with their different insecticide use history, and an admixture zone between these two patterns in Saint Georges and Oiapoque, in accordance with population genetic results. MAIN CONCLUSIONS: The present study highlights the need for regional-local vector surveillance and transnational collaboration between neighboring countries to assess the impact of implemented vector control strategies, promote timely actions and develop preparedness plans.


Assuntos
Aedes/efeitos dos fármacos , Aedes/genética , Resistência a Inseticidas/genética , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Mutação/genética , Animais , Biodiversidade , Brasil , Guiana Francesa , Genótipo , Resistência a Inseticidas/efeitos dos fármacos
20.
Nat Commun ; 10(1): 4237, 2019 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-31530873

RESUMO

The codling moth Cydia pomonella, a major invasive pest of pome fruit, has spread around the globe in the last half century. We generated a chromosome-level scaffold assembly including the Z chromosome and a portion of the W chromosome. This assembly reveals the duplication of an olfactory receptor gene (OR3), which we demonstrate enhances the ability of C. pomonella to exploit kairomones and pheromones in locating both host plants and mates. Genome-wide association studies contrasting insecticide-resistant and susceptible strains identify hundreds of single nucleotide polymorphisms (SNPs) potentially associated with insecticide resistance, including three SNPs found in the promoter of CYP6B2. RNAi knockdown of CYP6B2 increases C. pomonella sensitivity to two insecticides, deltamethrin and azinphos methyl. The high-quality genome assembly of C. pomonella informs the genetic basis of its invasiveness, suggesting the codling moth has distinctive capabilities and adaptive potential that may explain its worldwide expansion.


Assuntos
Cromossomos de Insetos/genética , Resistência a Inseticidas , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Mariposas/genética , Animais , Duplicação Gênica , Genoma de Inseto , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Mariposas/metabolismo , Feromônios/metabolismo , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas , Receptores Odorantes/genética , Receptores Odorantes/metabolismo
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