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1.
Rev Soc Bras Med Trop ; 52: e20180459, 2019 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-31365621

RESUMO

INTRODUCTION: The ability of Vitex trifolia and Vitex negundo essential oils to kill Aedes aegypti and Culex quinquefasciatus larvae was evaluated. METHODS: The larvae were treated with their respective essential oils at 50-125 ppm concentration. RESULTS: LC50 and LC90 for V. trifolia against Ae. aegypti and C. quinquefasciatus, and those for V. negundo against Ae. aegypti were 57.7+0.4, 77.9+0.9 ppm and 55.17+3.14, 78.28+2.23 ppm, and 50.86+0.9, 73.12+1.3 ppm, respectively. Eucalyptol and caryophyllene were the major components in Vitex trifolia and Vitex negundo essential oil, respectively. CONCLUSIONS: This study revealed potential larvicidal properties of essential oil from V. trifolia.


Assuntos
Aedes/efeitos dos fármacos , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Óleos Voláteis/farmacologia , Vitex/química , Animais , Inseticidas/isolamento & purificação , Dose Letal Mediana , Óleos Voláteis/isolamento & purificação
2.
Pestic Biochem Physiol ; 159: 107-117, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400772

RESUMO

Latrophilin (LPH) is an adhesion G protein-coupled receptor (aGPCR) that participates in multiple essential physiological processes. Our previous studies have shown that lph is not only indispensable for the development and reproduction of red flour beetles (Tribolium castaneum), but also for their resistance against dichlorvos or carbofuran insecticides. However, the regulatory mechanism of lph-mediated insecticide susceptibility remains unclear. Here, we revealed that knockdown of lph in beetles resulted in opposing changes in two chemoreception genes, chemosensory protein 10 (CSP10) and odorant-binding protein C01 (OBPC01), in which the expression of TcCSP10 was downregulated, whereas the expression of TcOBPC01 was upregulated. TcCSP10 and TcOBPC01 were expressed at the highest levels in early pupal and late larval stages, respectively. High levels of expression of both these genes were observed in the heads (without antennae) of adults. TcCSP10 and TcOBPC01 were significantly induced by dichlorvos or carbofuran between 12 and 72 h (hrs) after exposure, suggesting that they are likely associated with increasing the binding affinity of insecticides, leading to a decrease in sensitivity to the insecticides. Moreover, once these two genes were knocked down, the susceptibility of the beetles to dichlorvos or carbofuran was enhanced. Additionally, RNA interference (RNAi) targeting of lph followed by exposure to dichlorvos or carbofuran also caused the opposing expression levels of TcCSP10 and TcOBPC01 compared to the expression levels of wild-type larvae treated with insecticides alone. All these results indicate that lph is involved in insecticide susceptibility through positively regulating TcCSP10; and the susceptibility could also further partially compensated for through the negative regulation of TcOBPC01 when lph was knockdown in the red flour beetle. Our studies shed new light on the molecular regulatory mechanisms of lph related to insecticide susceptibility.


Assuntos
Proteínas de Insetos/metabolismo , Inseticidas/farmacologia , Receptores de Peptídeos/metabolismo , Tribolium/efeitos dos fármacos , Tribolium/metabolismo , Animais , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/genética , Proteínas de Insetos/genética
3.
Pestic Biochem Physiol ; 159: 136-143, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400775

RESUMO

Cytochrome P450s are part of a super-gene family that has undergone gene duplication, divergence, over-expression and, in some cases, loss of function. One such case is the 91-R and 91-C strains of common origin, in Drosophila melanogaster, whereby 91-R (DDT resistant strain) overexpresses Cyp4p1 and Cyp4p2 and both genes are lost in 91-C (DDT susceptible strain). In this study, we used a comparative approach to demonstrate that transcription of Cyp4p1 and Cyp4p2 were constitutively up-regulated in the Drosophila melanogaster strain 91-R as compared to another DDT susceptible strain Canton-S which does not have a loss of function of these genes. Furthermore, significantly increased expression of Cyp4p1 and Cyp4p2 was induced in 91-R in response to sublethal DDT exposure, however, such induction did not occur in the DDT treated Canton-S. Additionally, fixed nucleotide variation within putative transcription factor binding sites of Cyp4p1 and Cyp4p2 promoters were observed between 91-R and Canton-S, however, their impact on transcription remains to be determined. Two GAL4/UAS transgenic strains with integrated heat shock-inducible Cyp4p1- or Cyp4p2-RNAi constructs within wild-type genetic backgrounds were developed. Following heat shock induction of Cyp4p1 and Cyp4p2 knockdown, these transgenic lines showed increased DDT mortality as compared to their corresponding non-heat shock controls. These results provide a functional link of Cyp4p1 and Cyp4p2 in conferring tolerance to DDT exposure.


Assuntos
DDT/farmacologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/metabolismo , Inseticidas/farmacologia , Animais , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Proteínas de Drosophila/genética , Resistência a Inseticidas/genética
4.
Pestic Biochem Physiol ; 159: 154-162, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400777

RESUMO

The migratory locust, Locusta migartoria, is a major agricultural insect pest and its resistance to insecticides is becoming more prevalent. Cytochrome P450 monooxygenases (CYPs) are important enzymes for biotransformations of various endogenous and xenobiotic substances. These enzymes play a major role in developing insecticide resistance in many insect species. In this study, we heterologously co-expressed a CYP enzyme (CYP6FD1) and cytochrome P450 reductase (CPR) from L. migartoria in Sf9 insect cells. The recombinant enzymes were assayed for metabolic activity towards six selected model substrates (luciferin-H, luciferin-Me, luciferin-Be, luciferin-PFBE, luciferin-CEE and 7-ethoxycoumarin), and four selected insecticides (deltamethrin, chlorpyrifos, carbaryl and methoprene). Recombinant CYP6FD1 showed activity towards 7-ethoxycoumarin and luciferin-Me, but no detectable activity towards the other luciferin derivatives. Furthermore, the enzyme efficiently oxidized deltamethrin to hydroxydeltamethrin through an aromatic hydroxylation in a time-dependent manner. However, the enzyme did not show any detectable activity towards the other three insecticides. Our results provide direct evidence that CYP6FD1 is capable of metabolizing deltamethrin. This work is a step towards a more complete characterization of the catalytic capabilities of CYP6FD1 and other xenobiotic metabolizing CYP enzymes in L. migratoria.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Família 6 do Citocromo P450/metabolismo , Proteínas de Insetos/metabolismo , Inseticidas/farmacologia , Locusta migratoria/efeitos dos fármacos , Locusta migratoria/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Família 6 do Citocromo P450/genética , Proteínas de Insetos/genética
5.
Pestic Biochem Physiol ; 159: 27-33, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400781

RESUMO

Imidacloprid has been used to control one of most serious pests, Bemisia tabaci. However, B. tabaci has developed imidacloprid resistance mainly by over-expressing CYP6CM1. It was reported that imidacloprid-resistant B. tabaci showed no or low level of cross-resistance against dinotefuran. Here, we expressed CYP6CM1 variants using Sf9/baculovirus and/or Drosophila S2 cells and showed that CYP6CM1 variants metabolized imidacloprid but not dinotefuran. In addition, we demonstrated that imidacloprid and pymetrozine competed for a CYP6CM1 variant more efficiently than dinotefuran, using a luminescent substrate competition assay. These results suggest that lack of metabolic activity of CYP6CM1 variants against dinotefuran caused no or low level of cross-resistance.


Assuntos
Guanidinas/metabolismo , Guanidinas/farmacologia , Hemípteros/efeitos dos fármacos , Hemípteros/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Neonicotinoides/metabolismo , Neonicotinoides/farmacologia , Nitrocompostos/metabolismo , Nitrocompostos/farmacologia , Animais , Hemípteros/genética , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Resistência a Inseticidas/genética , Triazinas/metabolismo , Triazinas/farmacologia
6.
Pestic Biochem Physiol ; 159: 34-40, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400782

RESUMO

The present study investigated the insecticidal activity of the different organic extracts from the entomopathogenic fungi, Cladosporium cladosporioides, Metarhizium anisopliae, Purpureocillium lilacinum, and Trichoderma longibrachiatum towards cotton aphid, Aphis gossypii. The methanol extracts from the mycelia and spores of C. cladosporioides and P. lilacinum exhibited the highest insecticidal activity against A. gossypii compared with other extracts, which LC50 values were recorded to be 57.60 and 94.18 ppm, respectively. The major constituents identified in both methanol extracts by GC-MS analysis were linoleic acid and palmitic acid. The methanol extracts of C. cladosporioides and P. lilacinum caused a voluminous increase in the total carbohydrates content of A. gossypii adults, while the total protein content was significantly decreased by both extracts. The activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were significantly reduced by methanol extracts. The P. lilacinum extract caused a considerable reduction in the activity of glutathione-S-transferase (GST), α- and ß-esterase by 28.9, 27.9 and 23.4%, respectively. Both extracts induced a significant increase in phenoloxidase and chitinase activity of A. gossypii adults. These results suggest that C. cladosporioides and P. lilacinum methanol extracts could be used as a promising approach for the management of A. gossypii in many economically crops.


Assuntos
Afídeos/efeitos dos fármacos , Gossypium/parasitologia , Inseticidas/farmacologia , Alanina Transaminase/genética , Alanina Transaminase/metabolismo , Animais , Quitinases/genética , Quitinases/metabolismo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Resistência a Inseticidas/genética , Dose Letal Mediana , Metanol/química , Monofenol Mono-Oxigenase/genética , Monofenol Mono-Oxigenase/metabolismo
7.
Pestic Biochem Physiol ; 159: 9-16, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400789

RESUMO

An L1024F substitution in the para gene, which encodes a subunit of the voltage-gated sodium channel, has been implicated in pyrethroid resistance in a mite pest, Halotydeus destructor, which attacks rape and other grain crops. A high-resolution melt (HRM) genotyping assay was developed for testing the relative pyrethroid susceptibility of different para genotypes and for high-throughput field screening of resistant alleles. The L1024F mutation was found to be incompletely recessive in phenotypic laboratory bioassays with the pyrethroid pesticide, bifenthrin. While the resistance ratio of heterozygotes (RS) to susceptible homozygotes (SS) was <6 in 24 h bioassays, the resistant homozygotes (RR) (with a resistance ratio > 200,000) survived the recommended field rate of bifenthrin (100 mgL-1). HRM genotyping of mites from field populations across Australia indicated the presence of resistant alleles in Western Australia and South Australia, but not in Victoria and New South Wales. The assay developed will be useful for routine screening of pyrethroid resistance, and the dominance relationships established here point to useful resistance management strategies involving the maintenance of reservoirs of susceptible mites to dilute resistant homozygotes in a population.


Assuntos
Inseticidas/farmacologia , Ácaros/efeitos dos fármacos , Piretrinas/farmacologia , Animais , Genótipo , Heterozigoto , Homozigoto , Resistência a Inseticidas/genética , Programas de Rastreamento , Ácaros/genética
8.
Exp Parasitol ; 204: 107732, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31374184

RESUMO

In the present study, the cytotoxic effects of amitraz, an octopamine receptor agonist on the reproductive system of engorged adult females of Rhipicephalus (Boophilus) annulatus were assessed using histology, electron microscopy and octopamine beta (OCTß) receptor transcriptional expression analysis. Adult immersion test (AIT) was performed by immersing the fully engorged female ticks for 2 min in different concentrations of amitraz (200, 250, 300, 350 ppm). Amitraz at the dose of 300 ppm, caused an adult tick mortality of 16.66 ±â€¯6.80 per cent, inhibition of fecundity of 75.80 per cent and hatching of 50 per cent of ova laid by treated ticks. Histological changes in the ovaries of ticks collected after 24 h of treatment with amitraz (300 ppm), in comparison with controls (distilled water/methanol) were identified by microscopical examination of sections (4  µm) stained using haematoxylin and eosin. These changes included reduction in size and basophilia of stage I oocytes, presence of cytoplasmic vacuoles of various sizes around germinal vesicle of stage II oocytes, wavy basement membrane of stage III oocytes and reduction in size and number of mature stage IV and V oocytes. Electron microscopy was employed for understanding the structural changes in the ultrathin sections (60 nm) of ovaries. Ticks treated with amitraz showed major ultrastructural changes such as irregular nuclear membrane, crystolysis of mitochondria and detachment of external and internal layers of basal lamina of oocytes. The cDNA synthesized from the total RNA of whole ticks and ovaries of ticks treated with amitraz along with controls were used for relative quantification of Octopamine ß receptor (OCTß-R) expression based on the 2-ΔΔCT method by quantitative real time PCR (qRT PCR). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as endogenous control. Down regulation of expression of OCTß-R mRNA in the ovaries of amitraz treated ticks was observed compared to controls. Thus, the inhibition of fecundity observed in the ticks treated with amitraz can be attributed to the major structural changes and decreased expression of OCT ß receptor mRNA induced by it in the ovary.


Assuntos
Inseticidas/farmacologia , Rhipicephalus/efeitos dos fármacos , Toluidinas/farmacologia , Análise de Variância , Animais , Membrana Basal/efeitos dos fármacos , Membrana Basal/ultraestrutura , Regulação para Baixo , Feminino , Fertilidade/efeitos dos fármacos , Expressão Gênica , Microscopia Eletrônica de Transmissão , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/ultraestrutura , Oócitos/efeitos dos fármacos , Oócitos/ultraestrutura , Ovário/anatomia & histologia , Ovário/efeitos dos fármacos , Ovário/ultraestrutura , Oviposição/efeitos dos fármacos , RNA Mensageiro/isolamento & purificação , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Amina Biogênica/agonistas , Receptores de Amina Biogênica/efeitos dos fármacos , Rhipicephalus/anatomia & histologia , Rhipicephalus/genética , Rhipicephalus/ultraestrutura , Espectrofotometria , Controle de Ácaros e Carrapatos/métodos , Vacúolos/efeitos dos fármacos , Vacúolos/ultraestrutura
9.
Cochrane Database Syst Rev ; 8: CD012736, 2019 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-31425624

RESUMO

BACKGROUND: Larviciding refers to the regular application of chemical or microbial insecticides to water bodies or water containers to kill the aquatic immature forms of the mosquito (the larvae and pupae). OBJECTIVES: To summarize research evidence evaluating whether larviciding with chemical or microbial insecticides prevents malaria transmission. SEARCH METHODS: We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE; Embase; CAB Abstracts; LILACS; the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP); ClinicalTrials.gov; and the ISRCTN registry up to 6 June 2019. SELECTION CRITERIA: We included cluster-randomized controlled trials (cRCTs), interrupted time series (ITS), randomized cross-over studies, non-randomized cross-over studies, and controlled before-and-after studies (CBAs) that compared larviciding with no larviciding. DATA COLLECTION AND ANALYSIS: We independently assessed trials for eligibility and risk of bias, and extracted data. We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS: Four studies (one cRCT, two CBAs, and one non-randomized cross-over design) met the inclusion criteria. All used ground application of larvicides (people hand-delivering larvicides); one evaluated chemical and three evaluated microbial agents. Studies were carried out in The Gambia, Tanzania, Kenya, and Sri Lanka. Three studies were conducted in areas where mosquito aquatic habitats were less extensive (< 1 km²), and one where habitats were more extensive (> 1 km²; a cross-over study from The Gambia).For aquatic habitats of less than 1 km², one cRCT randomized eight villages in Sri Lanka to evaluate chemical larviciding using insect growth regulator; and two CBA studies undertaken in Kenya and Tanzania evaluated microbial larvicides. In the cRCT, larviciding across all villages was associated with lower malaria incidence (rate ratio 0.24, 4649 participants, low-certainty evidence) and parasite prevalence (risk ratio (RR) 0.26, 5897 participants, low-certainty evidence) compared to no larviciding. The two CBA studies reported lower malaria prevalence during the intervention period (parasite prevalence RR 0.79, 95% confidence interval (CI) 0.71 to 0.89; 70,902 participants; low-certainty evidence). The Kenyan study also reported a reduction in the incidence of new malaria cases (RR 0.62, 95% CI 0.38 to 1.01; 720 participants; very low-certainty evidence).For aquatic habitats of more than 1 km², the non-randomized cross-over trial using microbial larvicides did not detect an effect for malaria incidence (RR 1.58, 95% CI 0.94 to 2.65; 4226 participants), or parasite prevalence (RR 1.15, 95% CI 0.41 to 3.20; 3547 participants); both were very low-certainty evidence. The Gambia trial also reported the mean haemoglobin level, and there was no difference across the four comparisons (mean difference -0.13, 95% CI -0.40 to 0.13; 3586 participants).We were unable to summarize or pool entomological outcomes due to unreported and missing data. AUTHORS' CONCLUSIONS: Most controlled studies on larviciding have been performed with microbial agents. Ground larviciding for non-extensive larval habitats may have an effect on malaria transmission, and we do not know if there is an effect in large-scale aquatic habitats. We found no studies using larviciding application techniques that could cover large aquatic habitats, such as aerial spraying using aircraft.


Assuntos
Reservatórios de Doenças/parasitologia , Inseticidas/farmacologia , Malária/prevenção & controle , Controle de Mosquitos/métodos , Animais , Culicidae , Ecossistema , Humanos , Análise de Séries Temporais Interrompida , Larva/efeitos dos fármacos , Ensaios Clínicos Controlados Aleatórios como Assunto/métodos
10.
J Agric Food Chem ; 67(33): 9210-9219, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31390203

RESUMO

The insecticidal and antifeedant activities of five 7-chloro-4-(1H-1,2,3-triazol-1-yl)quinoline derivatives were evaluated against the maize armyworm, Spodoptera frugiperda (J.E. Smith). These hybrids were prepared through a copper-catalyzed azide alkyne cycloaddition (CuAAC, known as a click reaction) and displayed larvicidal properties with LD50 values below 3 mg/g insect, and triazolyl-quinoline hybrid 6 showed an LD50 of 0.65 mg/g insect, making it 2-fold less potent than methomyl, which was used as a reference insecticide (LD50 = 0.34 mg/g insect). Compound 4 was the most active antifeedant derivative (CE50 = 162.1 µg/mL) with a good antifeedant index (56-79%) at concentrations of 250-1000 µg/mL. Additionally, triazolyl-quinoline hybrids 4-8 exhibited weak inhibitory activity against commercial acetylcholinesterase from Electrophorus electricus (electric-eel AChE) (IC50 = 27.7 µg/mL) as well as low anti-ChE activity on S. frugiperda larvae homogenate (IC50 = 68.4 µg/mL). Finally, molecular docking simulations suggested that hybrid 7 binds to the catalytic active site (CAS) of this enzyme and around the rim of the enzyme cavity, acting as a mixed (competitive and noncompetitive) inhibitor like methomyl. Triazolyl-quinolines 4-6 and 8 inhibit AChE by binding over the perimeter of the enzyme cavity, functioning as noncompetitive inhibitors. The results described in this work can help to identify lead triazole structures from click chemistry for the development of insecticide and deterrent products against S. frugiperda and related insect pests.


Assuntos
Inseticidas/síntese química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Quinolinas/química , Quinolinas/farmacologia , Spodoptera/efeitos dos fármacos , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Inibidores da Colinesterase/síntese química , Inibidores da Colinesterase/química , Inibidores da Colinesterase/farmacologia , Química Click , Simulação por Computador , Proteínas de Insetos/antagonistas & inibidores , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Inseticidas/química , Larva/enzimologia , Larva/crescimento & desenvolvimento , Simulação de Acoplamento Molecular , Doenças das Plantas/parasitologia , Spodoptera/enzimologia , Spodoptera/crescimento & desenvolvimento , Zea mays/parasitologia
11.
Rev Soc Bras Med Trop ; 52: e20190135, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31390442

RESUMO

INTRODUCTION: Musca domestica is resistant to many insecticides; hence, biological control is a suitable alternative. METHODS: We evaluated the lethality of strain Btk176 towards the larval and adult M. domestica and the histopathological effects in the larvae midgut. RESULTS: We observed 99% larval and 78.9% adult mortality within 48 hours of spore ingestion (dosage, 2.4×108 CFU/ml). The histopathological effects were consistent with cytotoxicity. PCR analysis showed the presence of the cry1Ba gene. Transmission electron microscopy revealed a bipyramidal parasporal body. Thurigiensin activity was not detected. CONCLUSIONS: The serovar, Btk176 might be a potential biocontrol agent for houseflies.


Assuntos
Bacillus thuringiensis , Toxinas Bacterianas/farmacologia , Moscas Domésticas/efeitos dos fármacos , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Análise de Variância , Animais , Contagem de Colônia Microbiana , Exotoxinas , Microscopia Eletrônica de Transmissão , Controle Biológico de Vetores/métodos , Reprodutibilidade dos Testes
12.
Pestic Biochem Physiol ; 158: 101-111, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378344

RESUMO

Standard chemical insecticides present mainly neurotoxic effects and are becoming less and less effective due to insects developing resistance to them. One of the innovative strategies to control insects pests is to find a way to increase the sensitivity of the target sites in the insect nervous system to the applied insecticides. In the presented research, we proposed menthol, a component of essential oils, as a factor increasing the effectiveness of bendiocarb, a carbamate insecticide. The aim of our study was to evaluate the potentiation of the bendiocarb effect by menthol. In toxicity tests performed on Periplaneta americana, menthol (0.1 µM) accelerated the lethal effect of bendiocarb, primarily in its low concentrations (lower than 0.05 mM). In the presence of menthol (1 and 0.1 µM), the ability of insects to turn back from its dorsal to the normal ventral side was significantly lower than with bendiocarb (1 µM) alone. We also evaluated the effectiveness of chemicals on the activity of the ventral nerve cord of the cockroach. In this preparation, bendiocarb (1 µM and higher concentrations) caused an irregular, spontaneous bursts of action potentials. The total nerve activity (including the response to stimulation and spontaneous firing) was much higher when bendiocarb was applied in the presence of menthol (1 µM). The effect of menthol was similar to the octopamine effect and was abolished by phentolamine, the octopamine receptor antagonist. Our results clearly indicated a strengthening effect of menthol on bendiocarb effectiveness; potentiation occurred through octopamine receptors activation.


Assuntos
Carbamatos/farmacologia , Baratas/efeitos dos fármacos , Inseticidas/farmacologia , Mentol/farmacologia , Óleos Voláteis/química , Fenilcarbamatos/farmacologia , Acetilcolinesterase/metabolismo , Animais , Interações de Medicamentos , Resistência a Inseticidas
13.
Pestic Biochem Physiol ; 158: 156-165, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378352

RESUMO

Culex pipiens is a main vector for Bancroftian filariasis, Rift Valley Fever and diseases caused by other viruses, leaving several peoples with disabilities. In recent years, plant derived compounds have received much attention as potential alternatives to synthetic chemicals due to their low toxicity to mammals and environmental persistence. Twenty-one monoterpenes from different chemical groups (hydrocarbons and oxygenated products) were evaluated against Culex pipiens larvae. In addition, in vivo biochemical studies including effects on acetylcholine esterase (AChE), acid and alkaline phosphatases (ACP and ALP), total adenosine triphosphatase (ATPase) and gamma-aminobutyric acid transaminase (GABA-T) were investigated. Furthermore, in silico studies including pharmacophore elucidation, ADMET analysis and molecular docking of these compounds were performed. Among all tested monoterpenes, hydrocarbons [p-cymene, (R)-(+)-limonene and (+)-α-pinene], acetates (cinnamyl acetate, citronellyl acetate, eugenyl acetate and terpinyl acetate), alcohols [(±)-ß-citronellol and terpineol], aldehydes [citral and (1R)-(-)-myrtenal] and ketone [(R)-(+)-pulegone] exhibited the highest larval toxicity with LC50 = 14.88, 27.97, 26.13, 2.62, 3.81, 2.74, 21.65, 1.64, 21.70, 21.76, 1.68 and 1.90 mg/L after 48 h of exposure, respectively. The compounds proved a significant inhibition of all tested enzymes except total ATPase. The biochemical and molecular docking studies proved that AChE and GABA-T were the main targets for the tested monoterpenes.


Assuntos
Culex/virologia , Inseticidas/farmacologia , Monoterpenos/farmacologia , Fosfatase Alcalina/metabolismo , Animais , Culex/patogenicidade , Filariose Linfática/transmissão , Ativação Enzimática/efeitos dos fármacos , Esterases/metabolismo , Simulação de Acoplamento Molecular , Transaminases/metabolismo
14.
Pestic Biochem Physiol ; 158: 166-174, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378353

RESUMO

Pesticidal properties of Bacillus thuringiensis and its associated toxic proteins is an ever-growing science with potential implications in biological pest management. In the present study 80 Bacillus thuringiensis isolates native to Uttarakhand Himalayas were evaluated for chitinolytic activity and potent ones (11 isolates) were further subjected to multiphasic characterization for their antifungal, insecticidal and synergistic properties with selected chemical insecticides. Although all the 11 potent isolates were biologically active, only three isolates (VLBt27, VLBt109 and VLBt238) showed >90% inhibition in radial growth of 3 out of 4 tested plant pathogenic fungi (Rhizoctonia solani, Fusarium oxysporum, Alternaria pori and Pyricularia oryzae). The key antagonism was manifested in the form of disruptions in growing tips and uneven mycelial thickenings. In insect bioassays (against Helicoverpa armigera, Mythimna separata and Thysanoplusia orichalcea), no considerable direct mortality was observed. However, the larval weight reduction was prominent in four isolates (VLBt27, VLBt38, VLBt109 and VLBt135) which accounts to >75% in first instar larvae of H. armigera. Joint action of these four isolates with chemical insecticides showed an overall additive interaction against Brevicoryne brassicae and synergism against H. armigera. All the isolates were compatible with tested insecticides at their field recommended doses except for chlorpyriphos with around 130 kDa protein as chitinase. The study identified VLBt27 and VLBt109, two native isolates of B. thuringiensis with potential antagonistic activity and synergism as well. These isolates have possible implications as single strategy against two diverse pest problems (pathogenic fungi and phytophagous insect) of agriculture with a view of reduced pesticide application.


Assuntos
Bacillus thuringiensis/fisiologia , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Animais , Quitinases/metabolismo , Controle Biológico de Vetores
15.
Pestic Biochem Physiol ; 158: 32-39, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378358

RESUMO

Mutations in the GABA-gated chloride channel are associated with resistance to cyclodiene organochlorine and phenyl pyrazole insecticides. The best characterised of these is A301S, which was initially identified in a Dieldrin resistant strain of Drosophila melanogaster. The orthologous mutation has been found in a variety of different crop pests including the diamond back moth Plutella xylostella. However, the contribution of this mutation to resistance in this species remains unclear. We have used the CRISPR/Cas9 system in order to edit Plutella xylostella PxGABARalpha1 to Serine at the 301 orthologous position (282 in PxGABARalpha1) in an insecticide sensitive strain isolated from Vero Beach (VB) USA. In this edited line, no high level of resistance is conferred to Dieldrin, Endosulfan or Fipronil, rather only a subtle shift in sensitivity which could not confer commercially important resistance. We conclude that the high level of commercial resistance to cyclodiene organochlorine and phenyl pyrazole insecticides observed in some field isolates of Plutella xylostella cannot arise from A282S in PxGABARalpha1 alone.


Assuntos
Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Animais , Sistemas CRISPR-Cas/genética , Dieldrin/farmacologia , Endossulfano/farmacologia , Resistência a Inseticidas/genética , Mariposas/genética , Mutação/genética , Pirazóis/farmacologia , Receptores de GABA-A/genética
16.
Pestic Biochem Physiol ; 158: 40-46, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378359

RESUMO

Aphis gossypii Glover is an economically important pest of numerous crops throughout the world. Some field populations of A.gossypii in China have developed moderate level of resistance to sulfoxaflor, a newly released sulfoximine insecticide for management of sap-feeding pests. To evaluate the effect of sulfoxaflor resistance on the fitness cost of A. gossypii, the life history traits of sulfoxaflor-resistant strain (SulR) and an isogenic susceptible strain (SS) were compared using the age-stage, two-sex life table approach. The results showed that the resistant strain had a reduction in fitness (relative fitness = 0.917), along with significantly decreases in longevity, fecundity, net reproductive (R0), mean generation time (T) and gross reproductive rate (GRR). Compared to the susceptible strain, SulR strain showing a shorter developmental duration of each nymph instar stage. Moreover, the adult pre-oviposition period (APOP) and total preoviposition period (TPOP) of SulR strain were also significantly shorter than that of the susceptible strain. Investigation of six development and reproduction related genes indicated that EcR, USP and JHBP were overexpressed in the SulR strain, while the mRNA transcript level of Vg was decreased significantly compared to the susceptible strain. These results suggest that there is a fitness cost associated with sulfoxaflor resistance in A. gossypii and the different expression of EcR, USP, JHBP, and Vg may play very important role in this trade-off.


Assuntos
Afídeos/efeitos dos fármacos , Inseticidas/farmacologia , Piridinas/farmacologia , Compostos de Enxofre/farmacologia , Animais , Afídeos/genética , Afídeos/metabolismo , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Resistência a Inseticidas/genética , Ninfa/efeitos dos fármacos , Ninfa/genética , Ninfa/metabolismo
17.
Pestic Biochem Physiol ; 158: 47-53, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378360

RESUMO

Buprofezin is a chitin synthesis inhibitor that is very effective against Homopteran pests, such as the white-backed planthopper (WBPH), S. furcifera (Horvath). In the present study, resistance selection, cross-resistance and mechanisms of buprofezin resistance were investigated in this planthopper species. However, the mechanism associated with resistance to growth regulator insecticides (IGRs) remains largely unknown. A resistant strain (Bup-R) with a resistance level (22-fold) to buprofezin was developed through continuous selection for 47 generations from a laboratory susceptible strain (Bup-S). The results showed that the Bup-R exhibited no cross-resistance to other tested insecticides. Synergism tests showed that piperonyl butoxide (PBO) (SR = 3.9-fold) and diethyl maleate (DEM) (SR = 1.8-fold) had synergistic effects on buprofezin toxicity in the resistant strain (F47). Enzyme activity results revealed an approximate 5.7-fold difference in cytochrome P450 monooxygenase and a 2-fold difference in glutathione S-transferase (GST) between the resistant and susceptible strains, suggesting that the increased activity of these two enzymes is likely the main detoxification mechanism involved in resistance to buprofezin in this species. Furthermore, the mRNA expression levels of cytochrome P450 (CYP) and GST genes by quantitative real-time PCR results indicated that sixteen P450 and one GST gene were significantly overexpressed in the Bup-R strain, among which thirteen P450 genes and one GST gene were >2-fold higher than in the Bup-S strain. The present study increases our knowledge of the buprofezin resistance mechanism in S. furcifera and provides a useful reference for integrated pest management (IPM) strategies.


Assuntos
Hemípteros/efeitos dos fármacos , Inseticidas/farmacologia , Tiadiazinas/farmacologia , Animais , Sistema Enzimático do Citocromo P-450/metabolismo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Hemípteros/metabolismo , Proteínas de Insetos/genética , Resistência a Inseticidas/genética , Maleatos/metabolismo , Butóxido de Piperonila/farmacologia , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase em Tempo Real
18.
Pestic Biochem Physiol ; 158: 54-60, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378361

RESUMO

Extensive planting of transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) has spurred increasingly rapid evolution of resistance in pests. In the pink bollworm, Pectinophora gossypiella, a devastating global pest, resistance to Bt toxin Cry1Ac produced by transgenic cotton is linked with mutations in a gene (PgCad1) encoding a cadherin protein that binds Cry1Ac in the larval midgut. We previously reported a long non-coding RNA (lncRNA) in intron 20 of cadherin alleles associated with both resistance and susceptibility to Cry1Ac. Here we tested the hypothesis that reducing expression of this lncRNA decreases transcription of PgCad1 and susceptibility to Cry1Ac. Quantitative RT-PCR showed that feeding susceptible neonates small interfering RNAs (siRNAs) targeting this lncRNA but not PgCad1 decreased the abundance of transcripts of both the lncRNA and PgCad1. Moreover, neonates fed the siRNAs had lower susceptibility to Cry1Ac. The results imply that the lncRNA increases transcription of PgCad1 and susceptibility of pink bollworm to Cry1Ac. The results suggest that disruption of lncRNA expression could be a novel mechanism of pest resistance to Bt toxins.


Assuntos
Bacillus thuringiensis/metabolismo , Proteínas de Bactérias/farmacologia , Caderinas/genética , Endotoxinas/farmacologia , Proteínas Hemolisinas/farmacologia , Mariposas/efeitos dos fármacos , RNA Longo não Codificante/genética , Transcrição Genética/genética , Animais , Bacillus thuringiensis/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mariposas/genética , Mariposas/metabolismo , Controle Biológico de Vetores
19.
Pestic Biochem Physiol ; 158: 61-68, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378362

RESUMO

Insecticide resistance in house fly populations is a major problem faced by livestock producers worldwide. A survey of insecticide resistance levels and pyrethroid resistance allele frequencies in the United States was conducted in 2008-09, but little is known about how resistance levels have changed over the last 10 years. In addition, new target-site pyrethroid resistance alleles that confer high levels of resistance have been recently identified in the voltage-sensitive sodium channel, and their frequencies in field populations are unknown. Our aim in this study was to reassess the resistance status of house flies from select locations in the United States by examining resistance levels against commonly used insecticides and frequencies of known resistance alleles. House flies were collected from animal production facilities in five different states between 2016 and 2018. Resistance levels to three insecticides (permethrin, tetrachlorvinphos, and methomyl), representing three classes of insecticides (pyrethroids, organophosphates and carbamates) varied geographically and were lowest in the population collected from New Mexico, intermediate in the population collected from Utah, and greatest in the population from Kansas. The recently identified 1B pyrethroid resistance allele increased dramatically in frequency compared to previous reports, most notably in populations from Kansas and Maryland, indicating that it may already be widespread around the United States. Based on comparison with historical data, the population collected from Kansas represents one of the most highly permethrin resistant populations ever sampled. If the alleles responsible for this level of resistance spread, pyrethroids may be of limited use for house fly control in the United States in the near future.


Assuntos
Moscas Domésticas/efeitos dos fármacos , Inseticidas/farmacologia , Animais , Carbamatos/farmacologia , Moscas Domésticas/genética , Resistência a Inseticidas/genética , Organofosfatos/farmacologia , Permetrina/farmacologia , Estados Unidos
20.
Pestic Biochem Physiol ; 158: 77-87, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378364

RESUMO

Pyrethroid-resistance in onion thrips, Thrips tabaci, has been reported in many countries including Japan. Identifying factors of the resistance is important to correctly monitoring the resistance in field populations. To identify pyrethroid-resistance related genes in T. tabaci in Japan, we performed RNA-Seq analysis of seven T. tabaci strains including two pyrethroid-resistant and five pyrethroid-susceptible strains. We identified a pair of single point mutations, T929I and K1774N, introducing two amino acid mutations, in the voltage-gated sodium channel gene, a pyrethroid target gene, in the two resistant strains. The K1774N is a newly identified mutation located in the fourth repeat domain of the sodium channel. Genotyping analysis of field-collected populations showed that most of the T. tabaci individuals in resistant populations carried the mutation pair, indicating that the mutation pair is closely associated with pyrethroid-resistance in Japan. Another resistance-related mutation, M918L, was also identified in part of the resistant populations. Most of the individuals with the mutation pair were arrhenotokous while all individuals with the M918L single mutation were thelytokous. The result of differentially expressed gene analysis revealed a small number of up-regulated detoxification genes in each resistant strain which might be involved in resistance to pyrethroid. However, no up-regulated detoxification genes common to the two resistant strains were detected. Our results indicate that the mutation pair in the sodium channel gene is the most important target for monitoring pyrethroid-resistance in T. tabaci, and that pyrethroid-resistant arrhenotokous individuals with the mutation pair are likely to be widely distributed in Japan.


Assuntos
Piretrinas/farmacologia , Tisanópteros/efeitos dos fármacos , Tisanópteros/metabolismo , Canais de Sódio Disparados por Voltagem/metabolismo , Animais , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Japão , Mutação/genética , Mutação Puntual/genética , Tisanópteros/genética , Canais de Sódio Disparados por Voltagem/genética
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