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1.
Braz. j. biol ; 83: e246436, 2023. tab, graf
Artigo em Inglês | MEDLINE, LILACS, VETINDEX | ID: biblio-1339391

RESUMO

Abstract Application of different fertilizers to check the efficiency of expression of Bt (Bacillus thuringiensis) gene in one of the leading commercialized crops (cotton) against Lepidopteran species is of great concern. The expression of Cry protein level can be controlled by the improvement of nutrients levels. Therefore, the myth of response of Cry toxin to different combinations of NP fertilizers was explored in three Bt cotton cultivars. Combinations include three levels of nitrogen and three levels of phosphorus fertilizers. Immunostrips and Cry gene(s) specific primer based PCR (Polymerase Chain Reaction) analysis were used for the presence of Bt gene that unveiled the presence of Cry1Ac gene only. Further, the ELISA (enzyme-linked immunosorbent assay) kit was used to quantify the expression of Cry1Ac protein. Under various NP fertilizers rates, the level of toxin protein exhibited highly significant differences. The highest toxin level mean was found to be 2.3740 and 2.1732 µg/g under the treatment of N150P75 kg ha-1 combination while the lowest toxin level mean was found to be 0.9158 and 0.7641 µg/g at the N50P25 kg ha-1 level at 80 and 120 DAS (Days After Sowing), respectively. It was concluded from the research that the usage of NP fertilizers has a positive relation with the expression of Cry1Ac toxin in Bt cotton. We recommend using the N150P50 kg ha-1 level as the most economical and practicable fertilizer instead of the standard dose N100P50 kg ha-1 to get the desired level of Cry1Ac level for long lasting plant resistance (<1.5). The revised dose of fertilizer may help farmers to avoid the cross-resistance development in contradiction of insect pests.


Resumo A aplicação de diferentes fertilizantes para verificar a eficiência da expressão do gene Bt (Bacillus thuringiensis) em uma das principais culturas comercializadas (algodão) contra espécies de lepidópteros é uma grande preocupação. A expressão do nível de proteína Cry pode ser controlada pela melhoria dos níveis de nutrientes. Portanto, o mito da resposta da toxina Cry a diferentes combinações de fertilizantes NP foi explorado em três cultivares de algodão Bt. As combinações incluem três níveis de nitrogênio e três níveis de fertilizantes de fósforo. A análise de PCR (reação em cadeia da polimerase) específica para o gene (s) Immunostrips e Cry (s) foi usada para a presença do gene Bt que revelou a presença do gene Cry1Ac apenas. Além disso, o kit ELISA (ensaio de imunoabsorção enzimática) foi usado para quantificar a expressão da proteína Cry1Ac. Sob várias taxas de fertilizantes NP, o nível de proteína de toxina exibiu diferenças altamente significativas. A média do nível mais alto de toxina foi de 2,3740 e 2,1732 µg / g sob o tratamento da combinação N150P75 kg ha-1, enquanto a média do nível mais baixo de toxina foi de 0,9158 e 0,7641 µg / g no nível de N50P25 kg ha-1 em 80 e 120 DAS (dias após a semeadura), respectivamente. Concluiu-se com a pesquisa que o uso de fertilizantes NP tem relação positiva com a expressão da toxina Cry1Ac no algodão Bt. Recomendamos o uso do nível de N150P50 kg ha-1 como o fertilizante mais econômico e praticável em vez da dose padrão N100P50 kg ha-1 para obter o nível desejado de nível de Cry1Ac para resistência de planta de longa duração (<1,5). A dose revisada de fertilizante pode ajudar os agricultores a evitar o desenvolvimento de resistência cruzada em contradição com as pragas de insetos.


Assuntos
Animais , Proteínas Hemolisinas/genética , Mariposas , Fósforo , Proteínas de Bactérias/genética , Resistência a Inseticidas , Plantas Geneticamente Modificadas/genética , Endotoxinas/genética , Fertilizantes , Toxinas de Bacillus thuringiensis , Larva , Nitrogênio
2.
Braz. j. biol ; 83: e247676, 2023. tab, graf
Artigo em Inglês | MEDLINE, LILACS, VETINDEX | ID: biblio-1345527

RESUMO

Abstract Development of insecticides resistance mainly hinge with managements techniques for the control of Jassid, Amrasca biguttutla biguttutla. Five insecticides were applied against field collected and laboratory rared jassid populations during the years of 2017 to 2019 to profile their resistance level against field population of jassid through leaf dip method. Very low resistance level was found in jassid against confidor whereas high level of resistance was observed by pyriproxyfen against other test insecticides. Gradual resistance was observed against diafenthiuron. It is concluded that for the management of Jassid repetition of same insecticide should be avoided. The use of confidor may be reduced to overcome resistance against Jassid.


Resumo Desenvolvimento da resistência a inseticidas principalmente em dobradiça com técnicas de manejo para o controle de jassid, Amrasca biguttutla biguttutla. Cinco inseticidas foram aplicados contra populações de jassídeos coletados em campo e em laboratório durante os anos de 2017 a 2019 para traçar o perfil de seu nível de resistência contra populações de jassídeos em campo através do método de imersão nas folhas. Nível de resistência muito baixo foi encontrado em jassid contra confidor, enquanto alto nível de resistência foi observado por piriproxifeno contra outros inseticidas de teste. Resistência gradual foi observada contra o diafenthiuron. Conclui-se que, para o manejo do jassid, a repetição do mesmo inseticida deve ser evitada. O uso de confidor pode ser reduzido para superar a resistência contra jassid.


Assuntos
Animais , Hemípteros , Inseticidas/farmacologia , Resistência a Inseticidas , Laboratórios
3.
J Insect Sci ; 22(3)2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35526103

RESUMO

The control of mosquito populations using insecticides is increasingly threatened by the spread of resistance mechanisms. Dieldrin resistance, conferred by point mutations in the Rdl gene encoding the γ-aminobutyric acid receptor, has been reported at high prevalence in mosquito populations in response to selective pressures. In this study, we monitored spatio-temporal dynamics of the resistance-conferring RdlR allele in Aedes (Stegomyia) albopictus (Skuse, 1895) and Culex (Culex) quinquefasciatus (Say, 1823) populations from Reunion Island. Specimens of both mosquito species were sampled over a 12-month period in three cities and in sites located at lower (<61 m) and higher (between 503 and 564 m) altitudes. Mosquitoes were genotyped using a molecular test detecting the alanine to serine substitution (A302S) in the Rdl gene. Overall, the RdlR frequencies were higher in Cx. quinquefasciatus than Ae. albopictus. For both mosquito species, the RdlR frequencies were significantly influenced by location and altitude with higher RdlR frequencies in the most urbanized areas and at lower altitudes. This study highlights environmental factors that influence the dynamics of insecticide resistance genes, which is critical for the management of insecticide resistance and the implementation of alternative and efficient vector control strategies.


Assuntos
Aedes , Culex , Inseticidas , Aedes/fisiologia , Animais , Culex/genética , Dieldrin , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mosquitos Vetores/genética , Reunião
4.
Parasit Vectors ; 15(1): 163, 2022 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-35527275

RESUMO

BACKGROUND: Malaria remains one of the most devastating diseases globally, and the control of mosquitoes as the vector is mainly dependent on chemical insecticides. Elevated temperatures associated with future warmer climates could affect mosquitoes' metabolic enzyme expression and increase insecticide resistance, making vector control difficult. Understanding how mosquito rearing temperatures influence their susceptibility to insecticide and expression of metabolic enzymes could aid in the development of novel tools and strategies to control mosquitoes in a future warmer climate. This study evaluated the effects of temperature on the susceptibility of Anopheles gambiae sensu lato (s.l.) mosquitoes to pyrethroids and their expression of metabolic enzymes. METHODS: Anopheles gambiae s.l. eggs obtained from laboratory-established colonies were reared under eight temperature regimes (25, 28, 30, 32, 34, 36, 38, and 40 °C). Upon adult emergence, 3- to 5-day-old female non-blood-fed mosquitoes were used for susceptibility tests following the World Health Organization (WHO) bioassay protocol. Batches of 20-25 mosquitoes from each temperature regime (25-34 °C) were exposed to two pyrethroid insecticides (0.75% permethrin and 0.05% deltamethrin). In addition, the levels of four metabolic enzymes (α-esterase, ß-esterase, glutathione S-transferase [GST], and mixed-function oxidase [MFO]) were examined in mosquitoes that were not exposed and those that were exposed to pyrethroids. RESULTS: Mortality in An. gambiae s.l. mosquitoes exposed to deltamethrin and permethrin decreased at temperatures above 28 °C. In addition, mosquitoes reared at higher temperatures were more resistant and had more elevated enzyme levels than those raised at low temperatures. Overall, mosquitoes that survived after being exposed to pyrethroids had higher levels of metabolic enzymes than those that were not exposed to pyrethroids. CONCLUSIONS: This study provides evidence that elevated temperatures decreased An. gambiae s.l. mosquitoes' susceptibility to pyrethroids and increased the expression of metabolic enzymes. This evidence suggests that elevated temperatures projected in a future warmer climate could increase mosquitoes' resistance to insecticides and complicate malaria vector control measures. This study therefore provides vital information, and suggests useful areas of future research, on the effects of temperature variability on mosquitoes that could guide vector control measures in a future warmer climate.


Assuntos
Anopheles , Inseticidas , Malária , Piretrinas , Animais , Esterases , Feminino , Resistência a Inseticidas , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Mosquitos Vetores , Permetrina/farmacologia , Piretrinas/farmacologia , Temperatura
5.
Parasit Vectors ; 15(1): 155, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35505366

RESUMO

BACKGROUND: Myanmar is one of the six countries in the Greater Mekong Subregion (GMS) of Southeast Asia. Malaria vectors comprise many Anopheles species, which vary in abundance and importance in malaria transmission among different geographical locations in the GMS. Information about the species composition, abundance, and insecticide resistance status of vectorial systems in Myanmar is scarce, hindering our efforts to effectively control malaria vectors in this region. METHODS: During October and November 2019, larvae and adult females of Anopheles mosquitoes were collected in three sentinel villages of Banmauk township in northern Myanmar. Adult female mosquitoes collected by cow-baited tent collection (CBTC) and adults reared from field-collected larvae (RFCL) were used to determine mortality rates and knockdown resistance (kdr) against deltamethrin using the standard WHO susceptibility test. Molecular species identification was performed by multiplex PCR and ITS2 PCR, followed by DNA sequencing. The kdr mutation at position 1014 of the voltage-gated sodium channel gene was genotyped by DNA sequencing for all Anopheles species tested. RESULTS: A total of 1596 Anopheles mosquitoes from seven morphologically identified species groups were bioassayed. Confirmed resistance to deltamethrin was detected in the populations of An. barbirostris (s.l.), An. hyrcanus (s.l.), and An. vagus, while possible resistance was detected in An. annularis (s.l.), An. minimus, and An. tessellatus. Anopheles kochi was found susceptible to deltamethrin. Compared to adults collected by CBTC, female adults from RFCL had significantly lower mortality rates in the four species complexes. A total of 1638 individuals from 22 Anopheles species were molecularly identified, with the four most common species being An. dissidens (20.5%) of the Barbirostris group, An. peditaeniatus (19.4%) of the Hyrcanus group, An. aconitus (13.4%) of the Funestus group, and An. nivipes (11.5%) of the Annularis group. The kdr mutation L1014F was only detected in the homozygous state in two An. subpictus (s.l.) specimens and in a heterozygous state in one An. culicifacies (s.l.) specimen. CONCLUSIONS: This study provides updated information about malaria vector species composition and insecticide resistance status in northern Myanmar. The confirmed deltamethrin resistance in multiple species groups constitutes a significant threat to malaria vector control. The lack or low frequency of target-site resistance mutations suggests that other mechanisms are involved in resistance. Continual monitoring of the insecticide resistance of malaria vectors is required for effective vector control and insecticide resistance management.


Assuntos
Anopheles , Malária , Animais , Anopheles/genética , Bovinos , Feminino , Resistência a Inseticidas/genética , Malária/prevenção & controle , Mosquitos Vetores/genética , Mianmar
6.
Pestic Biochem Physiol ; 183: 105088, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35430059

RESUMO

The bird-cherry-oat aphid, Rhopalosiphum padi, is a serious agricultural pest of Triticeae crops, and pyrethroids are the most widely used chemical pesticides for the control of the aphid. Our previous studies found that some R. padi field populations have developed resistance against pyrethroids; an M918L target-site mutation of the voltage gated sodium channel was present in the pyrethroid resistant individuals, while the high-level resistance to lambda-cyhalothrin revealed the presence of other mechanisms in the pest. Here, we conducted genome-wide transcriptional analysis for the lambda-cyhalothrin susceptible (SS) and resistant (LC-RR) strains of R. padi. Results indicated that 2457 genes were differently expressed between the SS and LC-RR strains. In the LC-RR, a total of 1265 and 1192 genes were up- and down-regulated, respectively. KEGG analysis implicated enrichment of P450 involved in insecticide metabolic pathways in the resistant transcriptome. qRT-PCR results confirmed that two P450 genes (CYP6DC1 and CYP380C47) were significantly overexpressed in the LC-RR individuals. Furthermore, RNA interference (RNAi) of CYP6DC1 or CYP380C47 significantly increased mortality of R. padi exposure to lambda-cyhalothrin. These results suggest that the overexpression of CYP6DC1 and CYP380C47 contributed to the lambda-cyhalothrin resistance in the pest. This study provides knowledge for further analyzing the molecular mechanism of resistance to pyrethroids in R. padi.


Assuntos
Afídeos , Inseticidas , Piretrinas , Animais , Afídeos/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Nitrilas , Piretrinas/farmacologia , Interferência de RNA , Transcriptoma
7.
Pestic Biochem Physiol ; 183: 105060, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35430063

RESUMO

Cytochrome P450-mediated detoxification plays an important role in the development of insecticide resistance. Previous studies have shown that cytochrome P450 CYP6B7 was induced by fenvalerate and involved in fenvalerate detoxification in Helicoverpa armigera. However, the transcriptional regulation of CYP6B7 induced by fenvalerate remains unclear. Here, a series of progressive 5' deletions of CYP6B7 promoter reporter genes were constructed, and the relative luciferase activities were detected. The results revealed that the relative luciferase activity of plasmid p (-655/-1) was significantly induced by fenvalerate. Further deletion of the region between -655 and -486 bp showed that the highest luciferase activity induced by fenvalerate was observed in plasmid p (-528/-1), while p (-485/-1) had the lowest fenvalerate-induced luciferase activity. Moreover, internal deletion and mutation in the region between -508 and -486 bp resulted in a significant reduction in fenvalerate-induced CYP6B7 promoter activity, suggesting that the cis-acting element responsible for fenvalerate in the CYP6B7 promoter was located between -508 and -486 bp. These results promote an understanding of the expression regulation mechanism of P450 genes that conferring resistance to insecticides.


Assuntos
Inseticidas , Mariposas , Piretrinas , Animais , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Luciferases , Mariposas/genética , Mariposas/metabolismo , Nitrilas , Piretrinas/farmacologia
8.
Pestic Biochem Physiol ; 183: 105061, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35430064

RESUMO

Pyrethroid resistance in the malaria vector Anopheles albimanus presents an obstacle to malaria elimination in the Americas. Here, An. albimanus CYP6P5 (the most overexpressed P450 in a Peruvian population) was functionally characterized. Recombinant CYP6P5 metabolized the type II pyrethroids, deltamethrin and α-cypermethrin with comparable affinities (KM of 3.3 µM ± 0.4 and 3.6 µM ± 0.5, respectively), but exhibited a 2.7-fold higher catalytic rate for α-cypermethrin (kcat of 6.02 min-1 ± 0.2) versus deltamethrin (2.68 min-1 ± 0.09). Time-course assays revealed progressive depletion of the above pyrethroids with production of four HPLC-detectable metabolites. Low depletion was obtained with type I pyrethroid, permethrin. Transgenic expression in Drosophila melanogaster demonstrated that overexpression of CYP6P5 alone conferred type II pyrethroid resistance, with only 16% and 55.3% mortalities in flies exposed to 0.25% α-cypermethrin and 0.15% deltamethrin, respectively. Synergist bioassays using P450 inhibitor piperonylbutoxide significantly recovered susceptibility (mortality = 73.6%, p < 0.001) in synergized flies exposed to 4% piperonylbutoxide, plus 0.25% α-cypermethrin, compared to non-synergized flies (mortality = 4.9%). Moderate resistance was also observed towards 4% DDT. These findings established the preeminent role of CYP6P5 in metabolic resistance in An. albimanus, highlighting challenges associated with deployment of insecticide-based control tools in the Americas.


Assuntos
Anopheles , Inseticidas , Malária , Piretrinas , Animais , Anopheles/genética , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Drosophila melanogaster/metabolismo , Resistência a Inseticidas/genética , Inseticidas/metabolismo , Inseticidas/farmacologia , Controle de Mosquitos , Mosquitos Vetores/genética , Piretrinas/metabolismo , Piretrinas/farmacologia
9.
Pestic Biochem Physiol ; 183: 105084, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35430074

RESUMO

The insect-specific epsilon class of glutathione S-transferases (GSTEs) plays important roles in insecticide detoxification in insects. In our previous work, five GSTEs were identified in Locusta migratoria, and two recombinant GSTEs, rLmGSTE1 and rLmGSTE4, showed high catalytic activity when 1-chloro-2,4-dinitrobenzene (CDNB) was used as a substrate. In this work, we further investigated whether these two GSTEs could metabolize three insecticides including malathion, deltamethrin and DDT. Using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC/MS) method, we found that rLmGSTE4, but not rLmGSTE1, can metabolize malathion and DDT. Malathion bioassays of L.migratoria after the expression of LmGSTE4 was suppressed by RNA interference (RNAi) showed increased insect mortality from 33.8% to 68.9%. However, no changes in mortality were observed in deltamethrin- or DDT-treated L.migratoria after the expression of LmGSTE4 was suppressed by RNAi. Our results provided direct evidences that LmGSTE4 participates in malathion detoxification in L.migratoria. These findings are important for understanding the mechanisms of insecticide resistance in L.migratoria and developing new strategies for managing the insect populations in the field.


Assuntos
Inseticidas , Locusta migratoria , Animais , DDT/metabolismo , DDT/farmacologia , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Inativação Metabólica/genética , Resistência a Inseticidas/genética , Inseticidas/metabolismo , Inseticidas/farmacologia , Locusta migratoria/genética , Locusta migratoria/metabolismo , Malation/metabolismo , Malation/farmacologia
10.
Pestic Biochem Physiol ; 183: 105085, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35430075

RESUMO

Nootkatone, a sesquiterpenoid isolated from Alaskan yellow cedar (Cupressus nootkatensis), is known to possess insect repellent and acaricidal properties and has recently been registered for commercial use by the Environmental Protection Agency. Previous studies failed to elucidate the mechanism of action of nootkatone, but we found a molecular overlay of picrotoxinin and nootkatone indicated a high degree of structural and electrostatic similarity. We therefore tested the hypothesis that nootkatone was a GABA-gated chloride channel antagonist, similar to picrotoxinin. The KD50 and LD50 of nootkatone on the insecticide-susceptible strain of Drosophila melanogaster (CSOR) showed resistance ratios of 8 and 11, respectively, compared to the cyclodiene-resistant strain of RDL1675, indicating significant cross-resistance. Nootkatone reversed GABA-mediated block of the larval CSOR central nervous system; nerve firing of 78 ± 17% of baseline in the CSOR strain was significantly different from 24 ± 11% of baseline firing in the RDL1675 strain (p = 0.035). This finding indicated that the resistance was expressed within the nervous system. Patch clamp recordings on D. melanogaster central neurons mirrored extracellular recordings where nootkatone inhibited GABA-stimulated currents by 44 ± 9% at 100 µM, whereas chloride current was inhibited 4.5-fold less at 100 µM in RDL1675. Taken together, these data suggest nootkatone toxicity in D. melanogaster is mediated through GABA receptor antagonism.


Assuntos
Drosophila melanogaster , Inseticidas , Animais , Resistência a Inseticidas , Inseticidas/toxicidade , Sesquiterpenos Policíclicos , Receptores de GABA , Ácido gama-Aminobutírico/farmacologia
11.
Pan Afr Med J ; 41: 109, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35432707

RESUMO

Despite major developments in malaria control over the past two decades, the disease continues to scourge the human population across the globe. Rising concerns such as insecticide resistance amongst vector mosquitoes are a cause of huge fear amongst healthcare providers and policymakers. Amidst such dire circumstances, a recent development may form the blueprint for future malaria control as for the first time ever researchers were able to decimate an entire mosquito population using gene-drive technology within a span of one year in a multi-generation, ecologically challenging study. Despite some concerns, the technology displayed a high potential of becoming a powerful tool in malaria control.


Assuntos
Culicidae , Tecnologia de Impulso Genético , Inseticidas , Malária , Animais , Culicidae/genética , Tecnologia de Impulso Genético/métodos , Humanos , Resistência a Inseticidas/genética , Malária/epidemiologia , Controle de Mosquitos/métodos , Mosquitos Vetores/genética
12.
PLoS One ; 17(4): e0267229, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35436317

RESUMO

BACKGROUND: Indoor residual spraying (IRS) using a capsule suspension formulation of the organophosphate insecticide, pirimiphos-methyl, has provided substantial malaria control in many communities in Africa. However, only one brand of this product has been recommended by the World Health Organisation for IRS. To help increase the diversity of the portfolio of IRS insecticides and offer suitable options to procurers and malaria vector control programmes, additional product brands of this highly effective and long-lasting insecticide formulation for IRS will be needed. METHODS: We evaluated the efficacy of Pirikool® 300CS, a new capsule suspension formulation of pirimiphos-methyl developed by Tianjin Yorkool, International Trading, Co., Ltd in standard WHO laboratory bioassays and experimental hut studies. The efficacy of the insecticide applied at 1000mg/m2 was assessed in laboratory bioassays for 6 months on cement, plywood and mud block substrates and for 12 months in cement and mud-walled experimental huts against wild free-flying pyrethroid-resistant Anopheles gambiae sensu lato in Covè, Benin. Actellic® 300CS, a WHO-recommended capsule suspension formulation of pirimiphos-methyl was also tested. WHO cylinder tests were performed to determine the frequency of insecticide resistance in the wild vector population during the hut trial. RESULTS: The vector population at the hut station was resistant to pyrethroids but susceptible to pirimiphos-methyl. Overall mortality rates of wild free-flying pyrethroid-resistant An. gambiae (s.l.) entering Pirikool®300CS treated experimental huts during the 12-month trial were 86.7% in cement-walled huts and 88% in mud-walled huts. Mortality of susceptible An. gambiae (Kisumu) and pyrethroid-resistant An. gambiae s.l. (Covè) mosquitoes in monthly wall cone bioassays on Pirikool® 300CS treated hut walls remained over 80% for 10-12 months. The laboratory bioassays corroborated the hut findings with Pirikool® 300CS on mud and wood block substrates but not on cement block substrates. CONCLUSION: Indoor residual spraying with Pirikool® 300CS induced high and prolonged mortality of wild pyrethroid-resistant malaria vectors for 10-12 months. Addition of Pirikool®300CS to the current portfolio of IRS insecticides will provide an extra choice of microencapsulated pirimiphos-methyl for IRS.


Assuntos
Anopheles , Inseticidas , Malária , Piretrinas , Animais , Benin , Resistência a Inseticidas , Inseticidas/farmacologia , Malária/prevenção & controle , Controle de Mosquitos , Mosquitos Vetores , Organofosfatos/farmacologia , Compostos Organotiofosforados , Piretrinas/farmacologia
13.
J Agric Food Chem ; 70(15): 4611-4619, 2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35410476

RESUMO

Chilo suppressalis has developed high levels of resistance to abamectin in many areas of China, while the underline resistance mechanisms are largely unclear. ATP-binding cassette (ABC) transporters function in transporting a large diversity of substrates including insecticides and play important roles in the detoxification metabolism of insects. In this study, synergism bioassay revealed that the ABC transporters were involved in the detoxification of C. suppressalis to abamectin. Six ABC transporter genes were upregulated in C. suppressalis after abamectin exposure, among which five genes CsABCC8, CsABCE1, CsABCF1, CsABCF2, and CsABCH1 were induced in the detoxification-related tissues. In addition, the five ABC transporters were recombinantly expressed in Sf9 cells, and the cytotoxicity assay showed that the viabilities of cells expressing CsABCC8 or CsABCH1 were significantly increased when compared with the viabilities of cells expressing EGFP after abamectin, chlorantraniliprole, cyantraniliprole, fipronil, and chlorpyrifos treatment, respectively. Overexpression of CsABCE1 significantly increased the viabilities of cells to abamectin, chlorantraniliprole, deltamethrin, and indoxacarb exposure, respectively. These results suggested that CsABCC8, CsABCE1, and CsABCH1 might participate in the detoxification and transport of abamectin and several other classes of insecticides in C. suppressalis. Our study provides valuable insights into the transport-related detoxification mechanisms in C. suppressalis and other insects.


Assuntos
Inseticidas , Mariposas , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Resistência a Inseticidas/genética , Inseticidas/toxicidade , Ivermectina/análogos & derivados , Larva , Mariposas/genética
14.
PLoS One ; 17(4): e0266453, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35472211

RESUMO

The intensification of agriculture leads to increased pesticide use and significant transformation from small fields towards large-scale monocultures. This may significantly affect populations of non-target arthropods (NTA). We aimed to assess whether the multigenerational exposure to plant protection products has resulted in the evolution of resistance to insecticides in the ground beetle Poecilus cupreus originating from different agricultural landscapes. Two contrasting landscapes were selected for the study, one dominated by small and another by large fields. Within each landscape the beetles were collected at nine sites representing range of canola coverage and a variety of habitat types. Part of the collected beetles, after acclimation to laboratory conditions, were tested for sensitivity to Proteus 110 OD-the most commonly used insecticide in the studied landscapes. The rest were bred in the laboratory for two consecutive generations, and part of the beetles from each generation were also tested for sensitivity to selected insecticide. We showed that the beetles inhabiting areas with medium and large share of canola located in the landscape dominated by large fields were less sensitive to the studied insecticide. The persistence of reduced sensitivity to Proteus 110 OD for two consecutive generations indicates that either the beetles have developed resistance to the insecticide or the chronic exposure to pesticides has led to the selection of more resistant individuals naturally present in the studied populations. No increased resistance was found in the beetles from more heterogeneous landscape dominated by small fields, in which spatio-temporal diversity of crops and abundance of small, linear off-crop landscape elements may provide shelter that allows NTAs to survive without developing any, presumably costly, resistance mechanisms.


Assuntos
Brassica napus , Besouros , Inseticidas , Praguicidas , Agricultura , Animais , Resistência a Inseticidas , Inseticidas/farmacologia , Melhoramento Vegetal
15.
Sci Rep ; 12(1): 6857, 2022 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-35478216

RESUMO

Pirimiphos-methyl is a pro-insecticide requiring activation by mosquito cytochrome P450 enzymes to induce toxicity while PBO blocks activation of these enzymes in pyrethroid-resistant vector mosquitoes. PBO may thus antagonise the toxicity of pirimiphos-methyl IRS when combined with pyrethroid-PBO ITNs. The impact of combining Olyset Plus and PermaNet 3.0 with Actellic 300CS IRS was evaluated against pyrethroid-resistant Anopheles gambiae s.l. in two parallel experimental hut trials in southern Benin. The vector population was resistant to pyrethroids and PBO pre-exposure partially restored deltamethrin toxicity but not permethrin. Mosquito mortality in experimental huts was significantly improved in the combinations of bendiocarb IRS with pyrethroid-PBO ITNs (33-38%) compared to bendiocarb IRS alone (14-16%, p < 0.001), demonstrating an additive effect. Conversely, mortality was significantly reduced in the combinations of pirimiphos-methyl IRS with pyrethroid-PBO ITNs (55-59%) compared to pirimiphos-methyl IRS alone (77-78%, p < 0.001), demonstrating evidence of an antagonistic effect when both interventions are applied in the same household. Mosquito mortality in the combination was significantly higher compared to the pyrethroid-PBO ITNs alone (55-59% vs. 22-26% p < 0.001) showing potential of pirimiphos-methyl IRS to enhance vector control when deployed to complement pyrethroid-PBO ITNs in an area where PBO fails to fully restore susceptibility to pyrethroids.


Assuntos
Anopheles , Malária , Piretrinas , Animais , Resistência a Inseticidas , Malária/prevenção & controle , Controle de Mosquitos , Mosquitos Vetores , Compostos Organotiofosforados , Butóxido de Piperonila/farmacologia , Piretrinas/toxicidade
16.
Genes (Basel) ; 13(4)2022 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-35456432

RESUMO

Metabolic-based resistance to insecticides limit the control of medically important pests, and it is extremely detrimental in the ongoing struggle to control disease vectors. Elucidating the fitness cost of metabolic resistance in major malaria vectors is vital for successful resistance management. We established the fitness cost of the 6.5kb structural variant (6.5kb-sv) between the duplicated CYP6P9a/b P450s using the hybrid strain generated from the crossing between two An. funestus laboratory strains. Furthermore, we assessed the cumulative impact of this marker with the duplicated P450 genes. We established that individuals that were homozygote for the resistant structural variant (SV) presented reduced fecundity and slow development relative to those that were homozygote for the susceptible SV. Furthermore, we observed that 6.5kb act additively with CYP6P9a and CYP6P9b to exacerbate the reduced fecundity and the increased development time of resistant mosquitoes since double/triple homozygote susceptible (SS/SS/SS) significantly laid more eggs and developed faster than other genotypes. Moreover, a restoration of susceptibility was noted over 10 generations in the insecticide-free environment with an increased proportion of susceptible individuals. This study highlights the negative impact of multiple P450-based resistance on the key physiological traits of malaria vectors. Such high fitness costs suggest that in the absence of selection pressure, the resistant individuals will be outcompeted in the field. Therefore, this should encourage future strategies based on the rotation of insecticides to reduce selection pressure and to slow the spread of pyrethroid resistance.


Assuntos
Anopheles , Inseticidas , Malária , Piretrinas , Animais , Anopheles/genética , Anopheles/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Humanos , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Malária/genética , Mosquitos Vetores/genética , Piretrinas/metabolismo , Piretrinas/farmacologia
17.
Infect Dis Poverty ; 11(1): 35, 2022 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-35462556

RESUMO

BACKGROUND: New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO. Resistance monitoring of such novel insecticides requires a robust protocol to monitor the development of resistance in natural populations. In this study, we comparatively used three different solvents to assess the susceptibility of malaria vectors to neonicotinoids across Africa. METHODS: Mosquitoes were collected from May to July 2021 from three agricultural settings in Cameroon (Njombe-Penja, Nkolondom, and Mangoum), the Democratic Republic of Congo (Ndjili-Brasserie), Ghana (Obuasi), and Uganda (Mayuge). Using the CDC bottle test, we compared the effect of three different solvents (ethanol, acetone, MERO) on the efficacy of neonicotinoids against Anopheles gambiae s.l. In addition, TaqMan assays were used to genotype key pyrethroid-resistant markers in An. gambiae and odds ratio based on Fisher exact test were used to evaluate potential cross-resistance between pyrethroids and clothianidin. RESULTS: Lower mortality was observed when using absolute ethanol or acetone alone as solvent for clothianidin (11.4‒51.9% mortality in Nkolondom, 31.7‒48.2% in Mangoum, 34.6‒56.1% in Mayuge, 39.4‒45.6% in Obuasi, 83.7‒89.3% in Congo and 71.1‒95.9% in Njombe pendja) compared to acetone + MERO for which 100% mortality were observed for all the populations. Similar observations were done for imidacloprid and acetamiprid. Synergist assays (PBO, DEM and DEF) with clothianidin revealed a significant increase of mortality suggesting that metabolic resistance mechanisms are contributing to the reduced susceptibility. A negative association was observed between the L1014F-kdr mutation and clothianidin resistance with a greater frequency of homozygote resistant mosquitoes among the dead than among survivors (OR = 0.5; P = 0.02). However, the I114T-GSTe2 was in contrast significantly associated with a greater ability to survive clothianidin with a higher frequency of homozygote resistant among survivors than other genotypes (OR = 2.10; P = 0.013). CONCLUSIONS: This study revealed a contrasted susceptibility pattern depending on the solvents with ethanol/acetone resulting to lower mortality, thus possibly overestimating resistance, whereas the MERO consistently showed a greater efficacy of neonicotinoids but it could prevent to detect early resistance development. Therefore, we recommend monitoring the susceptibility using both acetone alone and acetone + MERO (4 µg/ml for clothianidin) to capture the accurate resistance profile of the mosquito populations.


Assuntos
Anopheles , Inseticidas , Malária , Piretrinas , Acetona/farmacologia , Animais , Anopheles/genética , Camarões , Etanol/farmacologia , Resistência a Inseticidas , Inseticidas/farmacologia , Malária/prevenção & controle , Controle de Mosquitos , Mosquitos Vetores , Neonicotinoides/farmacologia , Piretrinas/farmacologia , Solventes/farmacologia
18.
Ecotoxicol Environ Saf ; 236: 113452, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35366565

RESUMO

Bt cotton successfully controlled major devastating pests in cotton,such as Helicoverpa armigera and Spodoptera exigua, and led to a drastic decrease in insecticide use in cotton fields, and it has been grown commercially worldwide. However, Bt cotton cultivation left Bt toxin residues in the soil, resulting in a response by its microbiome that caused potential environmental risks. In this research, the metagenomics analysis was performed to investigate the structure and functions of the soil bacterial community in the Bt cotton field from the Binzhou, Shandong province of China, where the Bt cotton has been cultivated for over fifteen years. Analysis of the function genes proved that the receptors of Bt toxins were absent in the soil bacteria and Bt toxins failed to target the soil bacteria. The microbiome structure and function were highly influenced by Bt cotton cultivation, however, no significant change in the total abundance of the bacteria was observed. Proteobacteria was the largest taxonomic group in the soil bacterial (42-52%) and its abundance was significantly increased after Bt cotton cultivation. The increase of Proteobacteria abundance resulted in an increase in ABC transporters gene abundance, indicating the improved ability of detoxification metabolism over Bt cotton cultivation. Xanthomonadales could be a biomarker of the Bt cotton group, whose abundance was significantly increased to contribute to the increase of the genes abundance in ABC transporters. The abundance of apoptosis genes was significantly decreased, and it might be related to the increase of Proteobacteria abundance by Bt cotton cultivation. In addition, Myxococcales was responsible for carotenoid biosynthesis, whoes genes abundance was significantly decreased due to the decrease of Myxococcales abundance by Bt cotton cultivation. These changes in soil bacterial community structure and functions indicate the influence by Bt cotton cultivation, leading to an understanding of the bacteria colonization patterns due to successive years of Bt cotton cultivation. These research results should be significant for the rational risk assessment of Bt cotton cultivation.


Assuntos
Toxinas de Bacillus thuringiensis , Mariposas , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Bactérias/genética , Proteínas de Bactérias/genética , Endotoxinas/genética , Gossypium/genética , Proteínas Hemolisinas/genética , Resistência a Inseticidas , Metagenômica , Mariposas/fisiologia , Plantas Geneticamente Modificadas/genética , Solo
19.
Parasit Vectors ; 15(1): 124, 2022 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-35410250

RESUMO

BACKGROUND: Insecticide-treated net (ITN) durability is evaluated using longitudinal bioefficacy and fabric integrity sampling post-distribution. Interceptor® G2 was developed for resistance management and contains two adulticides: alpha-cypermethrin and chlorfenapyr; it is a pro-insecticide that is metabolized into its active form by mosquito-detoxifying enzymes and may be enhanced when the mosquito is physiologically active. To elucidate the impact of bioassay modality, mosquito exposures of the alphacypermethrin ITN Interceptor® and dual adulticide Interceptor® G2 were investigated. METHODS: This study evaluated the performance of Interceptor® G2 compared to Interceptor® against local strains of mosquitoes in Tanzania. Unwashed and 20× times washed nets were tested. Efficacy of ITNs was measured by four bioassay types: (1) World Health Organisation (WHO) cone test (cone), (2) WHO tunnel test (tunnel), (3) Ifakara ambient chamber test (I-ACT) and (4) the WHO gold standard experimental hut test (hut). Hut tests were conducted against free-flying wild pyrethroid metabolically resistant Anopheles arabiensis and Culex quinquefasciatus. Cone, tunnel and I-ACT bioassays used laboratory-reared metabolically resistant An. arabiensis and Cx. quinquefasciatus and pyrethroid susceptible Anopheles gambiae sensu stricto and Aedes aegypti. RESULTS: Against resistant strains, superiority of Interceptor® G2 over Interceptor® was observed in all "free-flying bioassays". In cone tests (which restrict mosquito flight), superiority of Interceptor® over Interceptor® G2 was recorded. Mortality of unwashed Interceptor® G2 among An. arabiensis was lowest in hut tests at 42.9% (95% CI: 37.3-48.5), although this increased to 66.7% (95% CI: 47.1-86.3) by blocking hut exit traps so mosquitoes presumably increased frequencies of contact with ITNs. Higher odds of mortality were consistently observed in Interceptor® G2 compared to Interceptor® in "free-flying" bioassays using An. arabiensis: tunnel (OR = 1.42 [95% CI:1.19-1.70], p < 0.001), I-ACT (OR = 1.61 [95% CI: 1.05-2.49], p = 0.031) and hut (OR = 2.53 [95% CI: 1.96-3.26], p < 0.001). Interceptor® and Interceptor® G2 showed high blood-feeding inhibition against all strains. CONCLUSION: Both free-flying laboratory bioassays (WHO Tunnel and I-ACT) consistently measured similarly, and both predicted the results of the experimental hut test. For bioefficacy monitoring and upstream product evaluation of ITNs in situ, the I-ACT may provide an alternative bioassay modality with improved statistical power. Interceptor G2® outperformed Interceptor ® against pyrethroid-resistant strains, demonstrating the usefulness of chlorfenapyr in mitigation of malaria.


Assuntos
Anopheles , Mosquiteiros Tratados com Inseticida , Inseticidas , Malária , Piretrinas , Animais , Resistência a Inseticidas , Inseticidas/farmacologia , Macrolídeos , Malária/prevenção & controle , Controle de Mosquitos/métodos , Piretrinas/farmacologia , Tanzânia
20.
Vet Parasitol ; 304: 109699, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35390642

RESUMO

The horn fly, Haematobia irritans, is a blood-feeding parasitic fly with a global distribution that includes Europe, Africa, Asia, and the Americas. The fly has a major detrimental economic impact upon cattle production, with losses estimated at over $800 million annually in the United States and $2.5 billion in Brazil alone. Insecticide resistance in specific horn fly populations has been a problem for many years and there are several mechanisms whereby resistance develops. Little is known about the complement of metabolic enzymes encoded by the horn fly's genome that might provide the fly with detoxification or sequestration pathways to survive insecticide treatments. The cytochrome P450, glutathione S-transferase, and esterase enzyme families contain members that are capable of sequestering and/or detoxifying xenobiotic molecules such as insecticides. We sought to develop a comprehensive dataset of metabolic enzyme-encoding transcript sequences from the adult horn fly, as this is the life stage whose actions directly impose the economic costs to cattle producers. We used an Illumina paired-end read RNA-Seq approach to determine the adult horn fly transcriptomes from laboratory and field populations of horn flies with varying levels of pesticide resistance, including untreated and pyrethroid-treated newly eclosed adult flies. We followed with bioinformatic analyses to discern sequences putatively encoding cytochrome P450, esterase, and GST enzymes. We utilized read-mapping of RNA-Seq data and quantitative real-time polymerase chain reaction (qRT-PCR) to examine gene expression levels of specific P450 transcripts in several fly populations with varying degrees of pesticide resistance.


Assuntos
Inseticidas , Muscidae , Animais , Bovinos , Sistema Enzimático do Citocromo P-450/genética , Esterases/genética , Glutationa , Humanos , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Muscidae/genética , Transcriptoma , Transferases/genética
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