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1.
J Insect Sci ; 20(1)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32092133

RESUMO

Mating promotes reproductive activity, which may impact immune performance. Paradoxically, mating frequently challenges females' immunity (e.g., infections). Therefore, studies of postmating resource allocation between reproduction and survival are likely to shed new light on life-history trade-off and sexual selection. Here, we used RNAseq to test whether and how mating affected mRNA expression in genes related to reproduction and immunity in Spodoptera litura female moths. Results show a divergent change in the differentially expressed genes (DEGs) between reproduction and immunity: the immune response was largely downregulated shortly after mating (~6 h postmating), which has some recovery at 24 h postmating; reproductive response is trivial shortly after mating (~6 h postmating), but it largely upregulated at 24 h postmating (e.g., egg maturation related genes were highly upregulated). Considering the fact that most of the total DEGs downregulated from 0 to 6 h postmating (from 51/68 to 214/260) but most of the total DEGs upregulated at 24 h postmating (816/928), it is possible that trade-offs between reproduction and immunity occurred in mated females. For example, they may shut down immunity to favor sperm storage and save limited resources to support the increased energy required in reproduction (e.g., egg maturation and oviposition). Mating-induced infections should be trivial due to low polyandry in S. litura. A reduced immune defense may have no threat to S. litura survival but may benefit reproduction significantly. Furthermore, obvious expression changes were detected in genes related to hormone production, suggesting that endocrine changes could play important roles in postmating responses.


Assuntos
Copulação , Spodoptera/genética , Spodoptera/imunologia , Animais , Feminino , Expressão Gênica/fisiologia , Masculino , RNA Mensageiro , Reprodução/genética , Spodoptera/metabolismo
2.
Nat Commun ; 11(1): 162, 2020 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-31919357

RESUMO

The emergence of drug-resistant influenza type A viruses (IAVs) necessitates the development of novel anti-IAV agents. Here, we target the IAV hemagglutinin (HA) protein using multivalent peptide library screens and identify PVF-tet, a peptide-based HA inhibitor. PVF-tet inhibits IAV cytopathicity and propagation in cells by binding to newly synthesized HA, rather than to the HA of the parental virus, thus inducing the accumulation of HA within a unique structure, the inducible amphisome, whose production from the autophagosome is accelerated by PVF-tet. The amphisome is also produced in response to IAV infection in the absence of PVF-tet by cells overexpressing ABC transporter subfamily A3, which plays an essential role in the maturation of multivesicular endosomes into the lamellar body, a lipid-sorting organelle. Our results show that the inducible amphisomes can function as a type of organelle-based anti-viral machinery by sequestering HA. PVF-tet efficiently rescues mice from the lethality of IAV infection.


Assuntos
Antivirais/farmacologia , Hemaglutininas Virais/metabolismo , Vírus da Influenza A/crescimento & desenvolvimento , Infecções por Orthomyxoviridae/prevenção & controle , Peptídeos/farmacologia , Transportadores de Cassetes de Ligação de ATP/biossíntese , Animais , Autofagossomos/metabolismo , Cães , Avaliação Pré-Clínica de Medicamentos/métodos , Endossomos/metabolismo , Feminino , Células Madin Darby de Rim Canino , Camundongos , Camundongos Endogâmicos BALB C , Biblioteca de Peptídeos , Células Sf9 , Spodoptera
3.
Pestic Biochem Physiol ; 163: 227-234, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31973861

RESUMO

Odorant-degrading enzymes (ODEs) are considered to play key roles in odorant inactivation to maintain the odorant receptor sensitivity of insects. Some members of carboxylesterase (CXE) is a major sub-family of ODEs. However, only a few CXEs have been functionally characterized so far. In the present study, we cloned the antennal esterase SexiCXE11 cDNA full-length sequences from the male antennae of a notorious crop pest, Spodoptera exigua, and its encoded 538 amino acids. It was similar to other insect esterases and had the characteristics of a carboxylesterase. We expressed recombinant enzyme in High-Five insect cells and obtained the high level purified recombinant protein by affinity column. Furthermore we test enzyme activity toward its two acetate sex pheromone components (Z9,E12-Tetradecadienyl acetate, Z9E12-14:Ac and Z9-Tetradecenyl acetate, Z9-14:Ac) and other 18 ester plant volatiles. Our results demonstrated that SexiCXE11 degraded acetate sex pheromone components with similar degradation activities (about 15.75% with Z9E12-14:Ac and 19.28% with Z9-14:Ac) and plant volatiles with a relatively high activity such as pentyl acetate and (Z)-3-hexenyl caproate. SexiCXE11 had high hydrolytic activity with these two ester odorants (>50% degradation), which is characterized that although a ubiquitous expression esterase SexiCXE11 may be partly involved with olfaction. This study may facilitate a better understanding of moth ODE differentiation and suggest strategies for the development of new pest behavior inhibitors.


Assuntos
Atrativos Sexuais , Animais , Carboxilesterase , Ésteres , Proteínas de Insetos , Masculino , Feromônios , Plantas , Spodoptera
4.
Pestic Biochem Physiol ; 163: 241-253, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31973864

RESUMO

Spodoptera exigua nucleopolyhedrovirus (SeNPV) has been successfully applied as a bioinsecticide against S. exigua, one of the most devastating pests worldwide. However, due to limited information, the molecular mechanisms underlying interactions between S. exigua and SeNPV remain to be elucidated. In this study, RNA-Seq and differentially expressed gene (DEG) analysis of the S. exigua larva midgut were performed to explore molecular responses to SeNPV infection. A total of 1785 DEGs, including 935 upregulated and 850 downregulated genes, were identified in the midgut of SeNPV-infected S. exigua larvae. Ultrastructural observations showed that after SeNPV infection, the peritrophic matrix (PM) became a loose and highly porous surface with many clear ruptures; these changes were most likely associated with upregulation of chitin deacetylases. In addition, 124 putative innate immunity-related DEGs were identified and divided into several groups, including pattern recognition proteins, signaling pathways, signal modulation, antimicrobial peptides and detoxification. Interestingly, upregulation of some pattern recognition proteins, induction of the JAK/STAT signaling pathway and promotion of REPAT synthesis might be the main innate immunity responses occurring in the S. exigua larva midgut after SeNPV infection. According to quantitative real-time PCR, the expression profiles of 19 random DEGs were consistent with those obtained by RNA-Seq. These findings provide important basic information for understanding the molecular mechanisms of SeNPV invasion and the anti-SeNPV responses of the S. exigua midgut, promoting the utility of SeNPV as a bioinsecticide for the effective control of S. exigua and related pests.


Assuntos
Animais , Sistema Digestório , Larva , Spodoptera , Transcriptoma
5.
Insect Biochem Mol Biol ; 116: 103280, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31740346

RESUMO

Fall armyworm, Spodoptera frugiperda (J.E. Smith) is a major lepidopteran pest of maize in Brazil and its control particularly relies on the use of genetically engineered crops expressing Bacillus thuringiensis (Bt) toxins such as Cry1F. However, control failures compromising the efficacy of this technology have been reported in many regions in Brazil, but the mechanism of Cry1F resistance in Brazilian fall armyworm populations remained elusive. Here we investigated the molecular mechanism of Cry1F resistance in two field-collected strains of S. frugiperda from Brazil exhibiting high levels of Cry1F resistance. We first rigorously evaluated several candidate reference genes for normalization of gene expression data across strains, larval instars and gut tissues, and identified ribosomal proteins L10, L17 and RPS3A to be most suitable. We then investigated the expression pattern of ten potential Bt toxin receptors/enzymes in both neonates and 2nd instar gut tissue of Cry1F resistant fall armyworm strains compared to a susceptible strain. Next we sequenced the ATP-dependent Binding Cassette subfamily C2 gene (ABCC2) and identified three mutated sites present in ABCC2 of both Cry1F resistant strains: two of them, a GY deletion (positions 788-789) and a P799 K/R amino acid substitution, located in a conserved region of ABCC2 extracellular loop 4 (EC4) and another amino acid substitution, G1088D, but in a less conserved region. We further characterized the role of the novel mutations present in EC4 by functionally expressing both wild type and mutated ABCC2 transporters in insect cell lines, and confirmed a critical role of both sites for Cry1F binding by cell viability assays. Finally, we assessed the frequency of the mutant alleles by pooled population sequencing and pyrosequencing in 40 fall armyworm populations collected from maize fields in different regions in Brazil. We found that the GY deletion being present at high frequency. However we also observed many rare alleles which disrupt residues between sites 783-799, and their diversity and abundance in field collected populations lends further support to the importance of the EC4 domain for Cry1F toxicity.


Assuntos
Proteínas de Bactérias/farmacologia , Endotoxinas/farmacologia , Proteínas Hemolisinas/farmacologia , Proteínas de Insetos/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Spodoptera/genética , Sequência de Aminoácidos , Animais , Brasil , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Larva/efeitos dos fármacos , Larva/genética , Larva/crescimento & desenvolvimento , Alinhamento de Sequência , Spodoptera/efeitos dos fármacos , Spodoptera/crescimento & desenvolvimento
6.
Insect Biochem Mol Biol ; 117: 103283, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31759051

RESUMO

Cry protein toxins produced by Bacillus thuringiensis (Bt) are now widely used in sprays and transgenic crops to control insect pests. Most recently, ATP-binding cassette transporter proteins (ABC transporter), including ABCC2, ABCC3, ABCG1, ABCA2 and ABCB1, were reported as putative receptors for different Cry toxins. However, little is known about the regulatory mechanism involved in the expression of these ABC transporter genes. In the present study, a conserved target site of miR-998-3p was identified from the coding sequence (CDS) of ABCC2 in diverse lepidopteran insects. Luciferase reporter assays demonstrated that miR-998-3p could bind to the CDS of ABCC2 and down-regulate its expression through a conserved site and several non-conserved sites in three representative lepidopteran pests, including Helicoverpa armigera, Spodoptera exigua and Plutella xylostella. Injection of miR-998-3p agomir significantly reduced the abundance of ABCC2, accompanied by increased tolerance to Cry1Ac toxin in H. armigera, S. exigua and P. xylostella (Cry-S) larvae, while injection of miR-998-3p antagomir increased the abundance of ABCC2 dramatically, and thereby reduced the Cry1Ac resistance in a Cry1Ac resistant population of P. xylostella (GX-R). These results give a better understanding of the mechanisms of post-transcriptional regulation of ABCC2, and will be helpful for further studies on the role of miRNAs in the regulation of Cry1Ac resistance in lepidopteran pests.


Assuntos
Proteínas de Bactérias/farmacologia , Endotoxinas/farmacologia , Proteínas Hemolisinas/farmacologia , Proteínas de Insetos/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , MicroRNAs/metabolismo , Mariposas/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Animais , Proteínas de Insetos/metabolismo , Larva/efeitos dos fármacos , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Mariposas/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Mariposas/metabolismo , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Spodoptera/efeitos dos fármacos , Spodoptera/genética , Spodoptera/crescimento & desenvolvimento , Spodoptera/metabolismo
7.
Exp Parasitol ; 208: 107802, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31730782

RESUMO

In insects, diet plays an important role in growth and development. Insects can vary their diet composition based on their physiological needs. In this study we tested the influence of diet composition involving varying concentrations of macronutrients and zinc on the immune-tolerance following parasite and pathogen exposure in Spodoptera litura larvae. We also tested the insecticidal potential of Mesorhabditis belari, Enterobacter hormaechei and its secondary metabolites on Spodoptera litura larvae. The results shows macronutrient composition does not directly affect the larval tolerance to nematode infection. However, Zinc supplemented diet improved the immune tolerance. While larvae exposed to bacterial infection performed better on carbohydrate rich diet. Secondary metabolites from bacteria produced an immune response in dose dependent mortality. The study shows that the larvae maintained on different diet composition show varied immune tolerance which is based on the type of infection.


Assuntos
Enterobacter/fisiologia , Controle Biológico de Vetores , Rhabditoidea/fisiologia , Spodoptera/imunologia , Análise de Variância , Animais , Bioensaio , Carboidratos/administração & dosagem , Cromatografia Líquida de Alta Pressão , Dieta , Enterobacter/imunologia , Enterobacter/patogenicidade , Cromatografia Gasosa-Espectrometria de Massas , Tolerância Imunológica , Larva/imunologia , Dose Letal Mediana , Proteínas/administração & dosagem , Rhabditoidea/imunologia , Rhabditoidea/patogenicidade , Espectroscopia de Infravermelho com Transformada de Fourier , Spodoptera/fisiologia , Simbiose , Virulência , Zinco/administração & dosagem
8.
Bull Entomol Res ; 110(1): 84-95, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31190643

RESUMO

Spodoptera exigua Hübner and Sesamia cretica Led. (Lep., Noctuidae) are two important pests of corn. In this study, the effect of weed bands in the corn field, as weedy culture, on population density and damages of the pests were evaluated during two growing seasons (2016/2017). Cumulative insect days (CID) of each lepidopteran pest in weedy culture were compared with non-weedy culture. Results showed that CIDs of S. exigua and S. cretica in the non-weedy corn culture were significantly higher than the weedy corn culture. There was no significant difference between the total yield in the weedy and non-weedy cultures. Also, determinations of spatial distributions of the pests in the weedy and no-weedy treatments using Taylor's power law (TPL) and Iwao's patchiness (IP) showed that TPL provides a better fit for the data than IP and spatial distributions of both pests on both cultures were aggregative. Moreover, minor differences were observed between spatial distribution parameters of the pests in the weedy and non-weedy cultures. Green's model was used for developing a fixed-precision sequential sampling plan of the pests on the weedy and no-weedy treatments. Optimum sample sizes of S. exigua ranged from 532 to 5370 and 428 to 5296 plants and S. cretica varied from 297 to 2040 and 43 to 186 plants in the non-weedy and weedy cultures based on the desired precision level (0.25-0.1). Estimated stop lines of non-weedy and weedy cultures for S. exigua ranged from 0.000057 to 52.59 and 0.00029 to 58.87 and for S. cretica ranged from 1.59 to 111.5 and 2.09 to 98.03 larval cumulative numbers, respectively (0.25-0.1). The performance of the sampling plan was validated by resampling analysis using RVSP software. Results of the study can be used in the integrated pest management program of corn fields.


Assuntos
Agricultura/métodos , Distribuição Animal , Spodoptera , Animais , Densidade Demográfica , Zea mays
9.
Insect Sci ; 27(1): 22-32, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29704325

RESUMO

The Junonia coenia densovirus rapidly traverses the gut epithelium of the host lepidopteran without replicating in the gut cells. The ability of this virus to transcytose across the gut epithelium is of interest for the potential use of virus structural proteins as delivery vehicles for insecticidal peptides that act within the insect hemocoel, rather than in the gut. In this study, we used fall armyworm, Spodoptera frugiperda to examine the binding of the virus to brush border membrane vesicle proteins by two-dimensional ligand blot analysis. We also assessed the rate of flux of the primary viral structural protein, VP4 fused to eGFP with a proline-rich linker (VP4-P-eGFP) through the gut epithelium ex vivo in an Ussing chamber. The mechanisms involved with transcytosis of VP4-P-eGFP were assessed by use of inhibitors. Bovine serum albumin (BSA) and eGFP were used as positive and negative control proteins, respectively. In contrast to BSA, which binds to multiple proteins on the brush border membrane, VP4-P-eGFP binding was specific to a protein of high molecular mass. Protein flux was significantly higher for VP4-P-eGFP after 2 h than for albumin or eGFP, with rapid transcytosis of VP4-P-eGFP within the first 30 min. In contrast to BSA which transcytosed following clathrin-mediated endocytosis, the movement of VP4-P-eGFP was vesicle-mediated but clathrin-independent. The specificity of binding combined with the efficiency of transport across the gut epithelium suggest that VP4 will provide a useful carrier for insecticidal peptides active within the hemocoel of key lepidopteran pests including S. frugiperda.


Assuntos
Densovirus/fisiologia , Spodoptera/fisiologia , Transcitose/fisiologia , Proteínas Virais/fisiologia , Animais , Sistema Digestório/virologia , Fenômenos Fisiológicos do Sistema Digestório , Epitélio/fisiologia , Epitélio/virologia , Larva/crescimento & desenvolvimento , Larva/fisiologia , Larva/virologia , Spodoptera/crescimento & desenvolvimento , Spodoptera/virologia , Transcitose/genética
10.
Arch Insect Biochem Physiol ; 103(1): e21626, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31562754

RESUMO

Insects can produce various antimicrobial peptides (AMPs) upon immune stimulation. One class of AMPs are characterized by their high proline content in certain fragments. They are generally called proline-rich antimicrobial peptides (PrAMPs). We previously reported the characterization of Spodoptera litura lebocin-1 (SlLeb-1), a PrAMP proprotein. Preliminary studies with synthetic polypeptides showed that among the four deductive active fragments, the C-terminal fragment SlLeb-1 (124-158) showed strong antibacterial activities. Here, we further characterized the antibacterial and antifungal activities of 124-158 and its four subfragments: 124-155, 124-149, 127-158, and 135-158. Only 124-158 and 127-158 could agglutinate bacteria, while 124-158 and four subfragments all could agglutinate Beauveria bassiana spores. Confocal microscopy showed that fluorescent peptides were located on the microbial surface. Fragment 135-158 lost activity completely against Escherichia coli and Staphylococcus aureus, and partially against Bacillus subtilis. Only 124-149 showed low activity against Serratia marcescens. Negative staining, transmission, and scanning electron microscopy of 124-158 treated bacteria showed different morphologies. Flow cytometry analysis of S. aureus showed that 124-158 and four subfragments changed bacterial subpopulations and caused an increase of DNA content. These results indicate that active fragments of SlLeb-1 may have diverse antimicrobial effects against different microbes. This study may provide an insight into the development of novel antimicrobial agents.


Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Proteínas de Insetos/farmacologia , Spodoptera/química , Animais , Peptídeos Catiônicos Antimicrobianos/química , Bacillus subtilis/efeitos dos fármacos , Beauveria/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Proteínas de Insetos/química , Serratia marcescens/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos
11.
J Chem Ecol ; 46(1): 76-83, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31845135

RESUMO

Multiple species of phytophagous insects may co-occur on a plant and while plants can defend themselves from insect herbivory, plant responses to damage by different species and feeding guilds of insects may be asymmetric. Plants can trigger specific responses to elicitors/effectors in insect secretions altering herbivore performance. Recently, maize chitinases present in fall armyworm (FAW, Spodoptera frugiperda) frass were shown to act as effectors suppressing caterpillar-induced defenses in maize while increasing caterpillar performance. We investigated the effect of frass chitinase-mediated suppression of herbivore defenses in maize on the performance and preference of a subsequent insect herbivore from a different feeding guild, corn leaf aphid (Rhopalosiphum maidis). Aphid performance was highest on plants with FAW damage without frass chitinases compared to damaged plants with frass chitinases or undamaged plants. Plant exposure to frass chitinases post FAW damage also altered the production of herbivore-induced volatile compounds compared to damaged, buffer-treated plants. However, aphid preference to damaged, frass chitinase-treated plants was not different from damaged, buffer-treated plants or undamaged plants. This study suggests that frass effector-mediated alteration of plant defenses affects insect herbivores asymmetrically; while it enhances the performance of caterpillars, it suppresses the performance of subsequent herbivores from a different feeding guild.


Assuntos
Afídeos/fisiologia , Herbivoria/fisiologia , Zea mays/química , Animais , Afídeos/crescimento & desenvolvimento , Quitinases/metabolismo , Quitinases/farmacologia , Cromatografia Gasosa-Espectrometria de Massas , Larva/fisiologia , Folhas de Planta/química , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Spodoptera/fisiologia , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Zea mays/metabolismo
12.
Pest Manag Sci ; 76(1): 169-178, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31106516

RESUMO

BACKGROUND: The use of Bt plants has been the main strategy for controlling the fall armyworm Spodoptera frugiperda (J. E. Smith) in Brazil. However, many resistance cases were already registered. The resistance of S. frugiperda to the Vip3Aa20 protein was recently characterized under laboratory conditions but it is still efficient under field conditions. Here, resistance monitoring studies were conducted using phenotypic (purified protein and Bt maize leaves) and genotypic (F1 and F2 screen) methods to support insect resistance management (IRM) programs and preserve Vip3Aa20 technology on maize. RESULTS: Phenotypic monitoring with purified protein showed two populations significantly different from the susceptible strain on the second crop season in 2016. This number increased for the first and second crop seasons in 2017 in several regions. The genotypic monitoring estimated a mean frequency of the resistance allele of 0.0027 for the F1 screen and 0.0033 for the F2 screen. Three new resistant strains to Vip3Aa20 were selected from F2 screen assays. Complementation tests on these new resistant strains were positive with the previous resistant strain. CONCLUSION: Here we showed that the resistance allele of S. frugiperda to Vip3Aa20 protein is widely distributed in maize-producing regions in Brazil and its frequency increases throughout crop seasons. © 2019 Society of Chemical Industry.


Assuntos
Spodoptera/genética , Animais , Proteínas de Bactérias , Brasil , Endotoxinas , Frequência do Gene , Proteínas Hemolisinas , Proteínas de Insetos , Resistência a Inseticidas , Larva , Plantas Geneticamente Modificadas , Zea mays
13.
Pest Manag Sci ; 76(1): 47-54, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31157506

RESUMO

BACKGROUND: Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), a major lepidopteran pest in Latin and North America, has very recently invaded the continents of Africa and Asia. FAW has evolved resistance to different insecticides and transgenic corn expressing Bacillus thuringiensis (Bt) toxins. Here, we investigated the extent and mechanisms of resistance to diamide insecticides in a Brazilian field-collected FAW strain selected using chlorantraniliprole. RESULTS: Continuous laboratory selection of a field-collected FAW strain with chlorantraniliprole resulted in resistance ratios of 225-fold and > 5400-fold against chlorantraniliprole and flubendiamide, respectively, when compared with a susceptible strain. Pre-exposure to different synergists known to inhibit detoxification enzymes did not result in significantly increased larval toxicity, suggesting a minor role for metabolic resistance. Sequencing of the FAW ryanodine receptor (RyR) C-terminal domains II to VI revealed a single nucleotide polymorphism, resulting in a I4734M mutation recently said to confer target-site resistance to diamides in lepidopteran pests. Genotyping by pyrosequencing of field-collected FAW larvae sampled in the 2018 crop season suggests a low resistance allele frequency. Furthermore, we developed a fluorescent polymerase chain reaction (PCR)-based allelic discrimination assay for rapid genotyping of field-collected FAW samples, because diamides are increasingly used in Bt-/non-Bt corn. CONCLUSIONS: Recently, the identified RyR mutation has been shown to confer field resistance in other lepidopteran pests such as diamondback moth, tomato leafminer and striped rice stem borer. The developed PCR-based allelic discrimination assay will help to monitor the frequency and future spread of diamide resistance allele in FAW field populations and help to implement appropriate resistance management measures. © 2019 Society of Chemical Industry.


Assuntos
Spodoptera , Animais , Diamida , Resistência a Inseticidas , Inseticidas , Larva , Mutação , Canal de Liberação de Cálcio do Receptor de Rianodina
14.
Sci Total Environ ; 706: 135872, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855628

RESUMO

The fall armyworm (Spodoptera frugiperda J.E. Smith) is one of the most notorious pests of several crops in the world. However, to date, few studies have simulated the future distribution patterns of fall armyworm under rapid global changes. Though the relative influences of climate and land-use on species distribution might depend on the spatial scales of the studies, it is not known whether this rule is applicable to pests which mostly feed on crops. Here, we developed MaxEnt models to explore the distribution patterns of fall armyworm, as well as the relative influences of land-use change, topography and climate change on them. Under the present conditions and scenarios of RCP 2.6 and 8.5 (the most optimistic and pessimistic emissions scenarios, respectively), high potential habitats of fall armyworm were mostly recorded along the east coast areas of the USA, the State of Florida, Mexico, Central America, southern part of Brazil, central Africa, and southern Asia. Among all of the continents, Africa will face the greatest increase of the threats from fall armyworm in future. Under RCP 2.6 scenario, both the potential habitats and areas with increased habitat suitability were larger than those under RCP 8.5. Therefore, much more effort is required to control fall armyworm under RCP 2.6 scenario. Compared to climate change, land-use changes are more important in shaping the distribution patterns of fall armyworm. Therefore, the concentration of resources might modify the relative influence of climate and land-use in species distributions at large scales. Thus, regulating land-use might prove effective for mitigating the proliferation of fall armyworm. In general, C4 annual crops and managed pastures provide more suitable habitats for fall armyworm than C3 annual crops. Our findings demonstrate that delineating resource concentrations could provide a new approach towards controlling fall armyworm under current and future global change.


Assuntos
Spodoptera , Animais
15.
Pestic Biochem Physiol ; 162: 6-14, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31836055

RESUMO

The beet armyworm (Spodoptera exigua) is a highly polyphagous agricultural pest that is distributed worldwide. However, the adaptive mechanisms of S. exigua for various insecticides and defensive substances in host plants are unknown. Insect P450 monooxygenases play an important role in the detoxification of plant toxins and insecticides, leading to insecticides resistance. We investigated the induced effects of xanthotoxin exposure on detoxification enzyme activity and larval tolerance to α-cypermethrin in S. exigua. Our results showed that the lethal concentration (LC50) of α-cypermethrin for xanthotoxin-exposed larvae was 2.1-fold higher than in the control. Moreover, cytochrome P450 enzyme activity was significantly elevated by upregulation of P450 genes in treated larvae. RT-qPCR results showed that CYP9A10 expression level was significantly increased in all treatments, while maximal expression level was observed in xanthotoxin+α-cypermethrin-fed larvae. RNAi-mediated silencing of CYP9A10 further increased mortality by 18%, 26% and 35% at 48 h and by 27%, 43% and 55% at 72 h when larvae were exposed to diets containing chemicals as compared to the control. The results show that CYP9A10 might play an important role in xanthotoxin and α-cypermethrin detoxification in S. exigua. RNAi-mediated silencing could provide an effective synergistic agent for pest control or insecticide resistance management.


Assuntos
Inseticidas , Metoxaleno , Animais , Sistema Enzimático do Citocromo P-450 , Larva , Piretrinas , Interferência de RNA , Spodoptera
16.
Pestic Biochem Physiol ; 162: 86-95, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31836059

RESUMO

RNA interference (RNAi) efficiency varies among insects. RNAi is highly efficient and systemic in coleopteran insects but quite variable and inefficient in lepidopteran insects. Degradation of double-stranded RNA (dsRNA) by double-stranded ribonucleases (dsRNases) is thought to contribute to the variability in RNAi efficiency observed among insects. One or two dsRNases involved in dsRNA digestion have been identified in a few insects. To understand the contribution of dsRNases to reduced RNAi efficiency in lepidopteran insects, we searched the transcriptome of Spodoptera litura and identified six genes coding for DNA/RNA non-specific endonucleases. Phylogenetic analysis revealed the evolutionary expansion of dsRNase genes in insects. The mRNA levels of three midgut-specific dsRNases increased during the larval stage, and the highest dsRNA-degrading activity was detected in third-instar larvae. Proteins produced via the expression of three midgut-specific dsRNases, and the widely expressed dsRNase3, in a baculovirus system showed dsRNase activity for four out of five dsRNases tested. In addition, the increase in dsRNA-degrading activity and upregulation of dsRNase1 and 2 in larvae fed on cabbage leaves suggests that the diet of S. litura can influence dsRNase expression, dsRNA stability, and thus probably RNAi efficiency. This is the first report that multiple dsRNases function together in an RNAi-recalcitrant insect. The data included in this paper suggest that multiple dsRNases coded by the S. litura genome might contribute to the lower and variable RNAi efficiency reported in this and other lepidopteran insects.


Assuntos
Proteínas de Insetos , Tabaco , Animais , Insetos , Larva , Filogenia , Interferência de RNA , RNA de Cadeia Dupla , Spodoptera
17.
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
18.
PLoS One ; 14(12): e0227110, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31887188

RESUMO

We have developed a unified, versatile vector set for expression of recombinant proteins, fit for use in any bacterial, yeast, insect or mammalian cell host. The advantage of this system is its versatility at the vector level, achieved by the introduction of a novel expression cassette. This cassette contains a unified multi-cloning site, affinity tags, protease cleavable linkers, an optional secretion signal, and common restriction endonuclease sites at key positions. This way, genes of interest and all elements of the cassette can be switched freely among the vectors, using restriction digestion and ligation without the need of polymerase chain reaction (PCR). This vector set allows rapid protein expression screening of various hosts and affinity tags. The reason behind this approach was that it is difficult to predict which expression host and which affinity tag will lead to functional expression. The new system is based on four optimized and frequently used expression systems (Escherichia coli pET, the yeast Pichia pastoris, pVL and pIEx for Spodoptera frugiperda insect cells and pLEXm based mammalian systems), which were modified as described above. The resulting vector set was named pONE series. We have successfully applied the pONE vector set for expression of the following human proteins: the tumour suppressor RASSF1A and the protein kinases Aurora A and LIMK1. Finally, we used it to express the large multidomain protein, Rho-associated protein kinase 2 (ROCK2, 164 kDa) and demonstrated that the yeast Pichia pastoris reproducibly expresses the large ROCK2 kinase with identical activity to the insect cell produced counterpart. To our knowledge this is among the largest proteins ever expressed in yeast. This demonstrates that the cost-effective yeast system can match and replace the industry-standard insect cell expression system even for large and complex mammalian proteins. These experiments demonstrate the applicability of our pONE vector set.


Assuntos
Clonagem Molecular/métodos , Vetores Genéticos , Proteínas Recombinantes/isolamento & purificação , Transfecção/métodos , Animais , Aurora Quinase A/genética , Aurora Quinase A/isolamento & purificação , Escherichia coli/genética , Escherichia coli/metabolismo , Células HEK293 , Humanos , Quinases Lim/genética , Quinases Lim/isolamento & purificação , Pichia/genética , Pichia/metabolismo , Proteínas Recombinantes/genética , Células Sf9 , Spodoptera , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/isolamento & purificação , Quinases Associadas a rho/genética , Quinases Associadas a rho/isolamento & purificação
19.
Pan Afr Med J ; 33: 285, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31692877

RESUMO

Introduction: Pesticides are used as essential tools to control vector-borne diseases and agricultural pests and maintain quality and quantity crop production. Scientists attempt to use derived plant natural products due to environmental safety and low mammalian toxicity. Therefore, the cytotoxicity of malathion and Nepeta crispa essential oil against vertebrate L929 and invertebrate Sf9 cell lines were investigated. Methods: About 2×103 cells were placed into the wells of a 96-well plate experiments. Then appropriate concentrations of malathion and N. crispa essential oil added to the wells. The cells were allowed to grow for 3-5 days and estimated the cell numbers. Control cell wells contained only cells with DMSO. All treatments and controls repeated at least four replicates. Results: About 2×103 cells were placed into the wells of a 96-well plate experiments. Then appropriate concentrations of malathion and N. crispa essential oil added to the wells. The cells were allowed to grow for 3-5 days and estimated the cell numbers. Control cell wells contained only cells with DMSO. All treatments and controls repeated at least four replicates. Conclusion: Plant essential oil not only had no negative effects but also had boosting effects on the L929 cell viability. Nepeta crispa essential oil had negative effects on the Sf9 cell viability with the differences that derived plant natural products containing environmentally friendly and readily biodegradable derivatives, hydrolyzing rapidly in nature and nearly having no destructive effects on mammals and environment.


Assuntos
Malation/toxicidade , Nepeta/química , Óleos Voláteis/toxicidade , Praguicidas/toxicidade , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Camundongos , Óleos Voláteis/isolamento & purificação , Células Sf9 , Spodoptera
20.
Mycorrhiza ; 29(6): 615-622, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31724088

RESUMO

Most plant species naturally associate with arbuscular mycorrhizal fungi (AMF), which are known to promote crop nutrition and health in agroecosystems. However, information on how mycorrhizal associations affect plant biotic interactions that occur aboveground with foliar herbivores is limited and needs to be further addressed for the development of pest management strategies. With the objective to examine the influence of maize mycorrhizas on foliar herbivory caused by larvae of Spodoptera frugiperda, a serious pest in maize agroecosystems, we performed a fully factorial greenhouse pot experiment with three factors: Maize genotype (Puma and Milpal H318), AMF (with and without AMF, and without AMF with mineral P) and Insect herbivory (with and without S. frugiperda). Main results showed that inoculation with AMF improved plant growth and foliar P concentration, which coincided with increased foliar damage from herbivory and higher biomass of S. frugiperda larvae. A significant positive correlation between shoot P concentration and larval biomass was also observed. Finally, foliar herbivory by S. frugiperda slightly increased and decreased AMF root colonization in Puma and H318, respectively. In conclusion, our results show that maize plant benefits from AMF in terms of promotion of growth and nutrition, and may also increase the damage caused from insects by improving the food quality of maize leaves for larval growth, which seems to be linked to increased P uptake by the maize mycorrhizal association.


Assuntos
Micorrizas , Animais , Biomassa , Herbivoria , Larva , Raízes de Plantas , Spodoptera , Zea mays
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