Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.192
Filtrar
1.
PLoS One ; 15(8): e0235912, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32776931

RESUMO

Small heat shock proteins (sHsps) function in the response of insects to abiotic stress; however, their role in response to biotic stress has been under-investigated. Mythimna separata, the oriental armyworm, is polyphenetic and exhibits gregarious and solitary phases in response to high and low population density, respectively. In this study, three genes were identified encoding sHsps, namely MsHsp19.7, MsHsp19.8 and MsHsp21.4, and expression levels in solitary and gregarious M. separata were compared. The deduced protein sequences of the three MsHsps had molecular weights of 19.7, 19.8 and 21.4 kDa, respectively, and contained a conserved α-crystalline domain. Real-time PCR analyses revealed that the three sHsps were transcribed in all developmental stages and were dramatically up-regulated at the 6th larval stage in gregarious individuals. Expression of the three MsHsps was variable in different tissues of 6th instar larvae, but exhibited consistent up- and down-regulation in the hindgut and Malpighian tubules of gregarious individuals, respectively. In addition, MsHsp19.7 and MsHsp19.8 were significantly induced when solitary forms were subjected to crowding for 36 h, but all three MsHsps were down-regulated when gregarious forms were isolated. Our findings suggest that population density functions as a stress factor and impacts MsHsps expression in M. separata.


Assuntos
Proteínas de Choque Térmico Pequenas/genética , Proteínas de Insetos/genética , Mariposas/genética , Animais , Aglomeração , Regulação da Expressão Gênica , Larva/genética , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento
2.
Artigo em Inglês | MEDLINE | ID: mdl-32613481

RESUMO

Plutella xylostella, is the main pest infesting Brassica crops, and products based on Bacillus thuringiensis (Bt) are frequently used in strategies for its biocontrol. The present study aimed to evaluate whether a Bt-based bioinsecticide affects the predation behavior of Ceraeochrysa cincta when preying on P. xylostella. Three larval instars of the predator and the eggs and second-instar larvae of the moth were used, with the prey either untreated or treated with a Bt-based product (Xentari®). Results showed that, the first larval instar of C. cincta presented a type II functional response when preying upon untreated eggs, and a type III response when preying upon Bt-treated eggs, while the second and third instars presented type II and III responses, respectively, in both situations. The predator's first and third larval instars presented a type II functional response when preying upon untreated larvae and a type III response when preying upon Bt-treated larvae. However, the predator's second-instar larvae showed a type II response in both treatments. The results obtained allowed us to conclude that the Bt-based insecticide tested affects the predation behavior of the first-instar larvae of C. cincta on eggs and of both the first- and third-instar larvae of this predator on P. xylostella larvae.


Assuntos
Bacillus thuringiensis/química , Controle de Insetos , Insetos/fisiologia , Inseticidas/administração & dosagem , Controle Biológico de Vetores , Comportamento Predatório , Animais , Brasil , Insetos/efeitos dos fármacos , Resistência a Inseticidas , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Óvulo/efeitos dos fármacos , Óvulo/crescimento & desenvolvimento
3.
PLoS One ; 15(7): e0236174, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32722719

RESUMO

To escape or alleviate low temperatures in winter, insects have evolved many behavioral and physiological strategies. The purple stem borer, Sesamia inferens (Walker) is currently reported to be expanding their northern distributions and causing damage to summer maize in Xinxiang, China. However, their method of coping with the lower temperature in the new northern breeding area in winter is largely unknown. This paper investigates the overwinter site of S. inferens, and identifies the cold hardiness of larvae collected from a new breeding area in winter and explores a potential distribution based on low temperature threshold and on species distribution model MaxEnt. The results show that the overwintering location of the S. inferens population is more likely to be underground with increasing latitude and the population gradually moved down the corn stalk and drilled completely underground in later winter (February) in the north. The cold hardiness test shows the species is a moderate freeze-tolerant one, and Supercooling Points (SCP), Freezing Points (FP) and the incidence of mortality during the middle of winter (January, SCP: -7.653, FP: -6.596) were significantly lower than early winter (October) or late winter (March). Distribution in the new expansion area was predicted and the survival probability area was below N 35° for the Air Lower Lethal Temperature (ALLT50) and below N 40° for the Underground Lower Lethal Temperature (ULLT50). The suitable habitat areas for S. inferens with MaxEnt were also below N 40°. This study suggests the overwinter strategies of S. inferens have led to the colonization of up to a five degree more northerly overwintering latitude.


Assuntos
Aclimatação/fisiologia , Mariposas/fisiologia , Animais , Comportamento Animal , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Estações do Ano , Temperatura
4.
Ecotoxicol Environ Saf ; 201: 110828, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32531576

RESUMO

Toosendanin (TSN), which is extracted from the root bark of Melia toosendan Siebold and Zuccarini, has multiple modes of action against insects. Especially, this compound has a potent stomach poisoning activity against several lepidoptera pests. In this paper, the signs of toxicity, digestive enzymes activity, the histopathological changes and immuno-electron microscopic localization of TSN in the midgut epithelium of Mythimna separate Walker larvae were investigated for better understanding its action mechanism against insects. The bioassay results indicated that TSN has strong stomach poisoning against the fifth-instar larvae of M. separata (LC50 = 252.23 µg/mL). The typical poisoned symptom were regurgitation and paralysis. Activities of digestive enzymes had no obvious changes after treatment with LC80 dose of TSN. The midgut epithelial cells of insect were damaged by TSN, showing the degeneration of microvilli, hyperplasia of smooth endoplasmic reticulum and condensation of chromatin. Immunohistochemical analysis revealed that the gold particles existed on the microvilli of columnar cells and goblet cells, and gradually accumulated with the exacerbation of poisoning symptoms, showing that TSN targets on the microvilli of the midgutcells. Therefore, TSN acts on digestive system and locates in the microvilli of midgutcells of M. separata.


Assuntos
Sistema Digestório/efeitos dos fármacos , Medicamentos de Ervas Chinesas/farmacologia , Células Epiteliais/efeitos dos fármacos , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Microvilosidades/efeitos dos fármacos , Mariposas/efeitos dos fármacos , Animais , Sistema Digestório/ultraestrutura , Células Epiteliais/ultraestrutura , Microscopia Eletrônica de Transmissão , Microvilosidades/ultraestrutura , Mariposas/crescimento & desenvolvimento
5.
Artigo em Inglês | MEDLINE | ID: mdl-32448953

RESUMO

The combined use of chemicals and biological control is not always a successful strategy owing to the potential side effects on biocontrol agents. Lethal and sublethal effects of three commonly used insecticides were assessed on adult and immature stages of the egg parasitoid Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae). Recommended field concentrations of chlorantraniliprole, phosalone and spinosad caused mortality on preimaginal stages by 24, 87, and 98%, respectively. Lethal effects on parasitoid adults exposed to the insecticide dry residues were estimated as median lethal concentrations (LC50) that were 13.28, 0.25, and 0.03 µg a.i. ml-1 for chlorantraniliprole, phosalone, and spinosad, respectively. The effect of a low lethal concentration (LC30) of the compounds was evaluated on various adult biological traits, such as longevity, fecundity, emergence rate and other life table parameters. All compounds caused detrimental effects on all the estimated demographical indexes. Chlorantraniliprole affected the net reproductive rate, mean generation time and doubling time in comparison to the control; while, phosalone and spinosad adversely affected all assessed parameters. Phosalone and spinosad significantly reduced gross reproductive rate, net reproductive rate, intrinsic rate of increase, finite rate of increase, mean generation time and doubling time and reduced longevity, fecundity, emergence rate related to other biological parameters in comparison with control. The results suggest that all compounds are not fully compatible with the activity of T. brassicae, and that the inclusion of chlorantraniprole, spinosad and phosalone into Integrated Pest Management (IPM) involving this parasitoid has to be avoided. Nevertheless, further studies in open field conditions and on a multiple generation scale are necessary for providing a more definitive conclusion on the IPM suitability of the three tested insectcides.


Assuntos
Inseticidas/toxicidade , Macrolídeos/toxicidade , Compostos Organotiofosforados/toxicidade , Resíduos de Praguicidas/toxicidade , Vespas/efeitos dos fármacos , ortoaminobenzoatos/toxicidade , Animais , Combinação de Medicamentos , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/parasitologia , Mariposas/crescimento & desenvolvimento , Mariposas/parasitologia , Óvulo/efeitos dos fármacos , Óvulo/crescimento & desenvolvimento , Óvulo/parasitologia , Pupa/efeitos dos fármacos , Pupa/crescimento & desenvolvimento , Pupa/parasitologia
6.
Arch Insect Biochem Physiol ; 104(3): e21691, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32410326

RESUMO

In the present study, diel pattern in gut microbial communities in insects were evaluated. Lymantria dispar asiatica fourth instar larvae (72 ± 2 hr after molting) at noon (LdD) and midnight (LdN) were used for a comparative analysis of the gut microbial community. Ten bacterial operational taxonomic units (OTUs) were shared between LdD and LdN samples. One bacterial OTU was specific to LdD. The dominant gut microbes were OTU72 in LdD and OTU75 in LdN. A linear discriminant analysis effect size cladogram suggested that ten bacterial OTUs maintain significant differences in relative abundances between LdD and LdN. These results agreed with the discrete ellipses between LdD and LdN in principal coordinates analysis plots. Additionally, using phylogenetic investigation of communities by reconstruction of unobserved states, the gut microbial community was assigned to 23 functional terms, among which 22 exhibited significant differences between LdD and LdN. To conclude, the present study documented a diel pattern in the gut microbial community of L. dispar asiatica larvae.


Assuntos
Ritmo Circadiano , Microbioma Gastrointestinal/fisiologia , Mariposas/microbiologia , Animais , Bactérias/classificação , Larva/microbiologia , Mariposas/crescimento & desenvolvimento , Filogenia
7.
J Insect Sci ; 20(3)2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32365175

RESUMO

Six candidate sHSP genes were identified from the Glyphodes pyloalis transcriptome. All sHSP genes included full-length open reading frames and shared high similarity with the sequences of other lepidopteran species. These sHSP genes encoded 175-191 amino acid residues, and the predicted proteins had a molecular weight from 19.5 to 21.8 kDa. All GpsHSPs were expressed at lower levels at larval stages. All GpsHSPs were expressed at higher levels at diapaused, prepupal, or pupal stages, suggesting that sHSPs may be involved in metamorphosis in G. pyloalis. In addition to the developmental stage, extreme temperatures can induce variations in the expression of sHSPs genes. All GpsHSPs were significantly upregulated in larvae following exposure to heat shock, except GpHSP21.4 which downregulated at 4 h following exposure to the cold shock treatment. Furthermore, Starvation influenced the expression patterns of GpsHSPs as a function of the duration of food deprivation. Four GpsHSPs increased their expression with time of starvation until reaching to the peak level at 6 d of starvation. Finally, parasitism by the endoparasitoid Aulacocentrum confusum He et van Achterberg (Hymenoptera: Braconidae)-induced fluctuations in the expression of all GpsHSPs, and the expression varied with time after parasitization. Our results from this study strongly suggest functional differentiation within the sHSPs subfamily in G. pyloalis. The present study would provide further insight into the roles of sHSPs in G. pyloalis and novel avenues for promoting integrated management of this pest.


Assuntos
Proteínas de Choque Térmico Pequenas/genética , Proteínas de Insetos/genética , Mariposas/genética , Transcriptoma , Sequência de Aminoácidos , Animais , Feminino , Proteínas de Choque Térmico Pequenas/química , Proteínas de Choque Térmico Pequenas/metabolismo , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Larva/crescimento & desenvolvimento , Larva/metabolismo , Masculino , Mariposas/crescimento & desenvolvimento , Mariposas/metabolismo , Filogenia , Pupa/crescimento & desenvolvimento , Pupa/metabolismo , Alinhamento de Sequência
8.
J Insect Sci ; 20(3)2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32396202

RESUMO

A large number of ecdysteroid-regulated 16 kDa proteins (ESR16s) of insects have been isolated and annotated in GenBank; however, knowledge on insect ESR16s remain limited. In the present study, we characterized an ecdysteroid-regulated 16 kDa protein gene isolated in Chinese oak silkworm, Antheraea pernyi Guérin-Méneville ('ApESR16' in the following), an important silk-producing and edible insect. The obtained cDNA sequence of ApESR16 is 1,049 bp, harboring an open reading frame of 441 bp that encodes a polypeptide of 146 amino acids. CD-search revealed that ApESR16 contains the putative cholesterol/lipid binding sites on conserved domain Npc2_like (Niemann-Pick type C-2) belonging to the MD-2-related lipid-recognition superfamily. Sequence comparison revealed that ApESR16 exhibits 51-57% identity to ESR16s of lepidopteran insects, 36-41% identity to ESR16 or NPC2a of nonlepidopteran insects, and 28-32% identity to NPC2a of vertebrates, indicating a high sequence divergence during the evolution of animals. Phylogenetic analysis found that the used sequences were divided into two groups corresponding to vertebrates and invertebrates, and the used insect sequences were also well clustered according to their families. The A. pernyi ESR16 mRNA is expressed during all four developmental stages and in all tested tissues. Injection of 20-hydroxyecdysone (20-E) into A. pernyi diapausing pupae triggering diapause termination induced upregulation of ESR16 mRNA compared to the diapausing pupae, with the highest expression level at day 2 in the ovaries but day 12 in the fat body. Our results suggested that ApESR16 might be a diapause-related gene and plays a vital role in the pupal diapause of A. pernyi.


Assuntos
Ecdisteroides/metabolismo , Regulação da Expressão Gênica , Proteínas de Insetos/genética , Mariposas/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Feminino , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Masculino , Mariposas/crescimento & desenvolvimento , Mariposas/metabolismo , Filogenia , Pupa/crescimento & desenvolvimento , Pupa/metabolismo , Alinhamento de Sequência
9.
Gene ; 749: 144712, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32360412

RESUMO

The quantitative real-time polymerase chain reaction (qRT-PCR) has rapidly become the most sensitive and accurate method for the quantitative analysis of gene expression. Normalization of gene expression to that of relatively stably expressed housekeeping genes is required to facilitate the study of gene expression and to obtain more accurate RT-PCR data. However, no studies of the stability of expression of housekeeping genes in Lymantria dispar have been reported. In the present study, BestKeeper, GeNorm and NormFinder statistical software was used to evaluate the expression of thirteen candidate reference genes in L. dispar under different conditions. The expression levels of candidate reference genes were determined for two biological factors (developmental stages and tissues) and four abiotic treatments (temperature, insecticide, CO2 and starvation). The results showed that the best candidate reference genes in L. dispar were TUB, AK, RPS15 for developmental stages, RPL32 and GAPDH for tissues, ACTB and EF1-α for CO2 stress, GAPDH and RPL32 for temperature stress, RPS3 and GAPDH for insecticide stress, and GAPDH and RPS3 for starvation stress. In summary, EF1-α and TUB are preferential housekeeping genes in L. dispar under various conditions. These results provide a basis for the further study of functional genes of L. dispar.


Assuntos
Genes de Insetos , Mariposas/genética , Animais , Dióxido de Carbono , Primers do DNA , Privação de Alimentos , Expressão Gênica , Genes Essenciais , Inseticidas , Mariposas/crescimento & desenvolvimento , Mariposas/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Estresse Fisiológico/genética , Temperatura
10.
Arch Insect Biochem Physiol ; 104(3): e21687, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32342573

RESUMO

The economic loss in soybean crops caused by the Lepidoptera insects has encouraged the search for new strategies to control this pest, which are currently based on synthetic insecticides. This paper evaluated the ability of ApTI (Adenanthera pavonina trypsin inhibitor) to inhibit trypsin-like proteins from Anticarsia gemmatalis by docking, molecular dynamics, and enzymatic and survival assay. The docking and molecular dynamic simulation between trypsin and ApTI were performed using the program CLUSPRO and NAMD, respectively. The inhibitory constant Ki and the inhibition type were determined through chromogenic assays. The survival assay of neonatal larvae under treatment with artificial diet supplemented with ApTI was also performed. The ApTI binding site was predicted to block substrate access to trypsin due to four interactions with the enzyme, producing a complex with a surface area of 1,183.7 Å2 . The kinetic analysis revealed a noncompetitive tight-binding mechanism. The survival curves obtained using Kaplan-Meier estimators indicated that the highest larvae mortality was 60%, using 1.2 mg of ApTI per 100 ml of artificial diet. The in vitro, in vivo, and in silico studies demonstrated that ApTI is a strong noncompetitive inhibitor of trypsin with biotechnological potential for the control of A. gemmatalis insect.


Assuntos
Mariposas/efeitos dos fármacos , Proteínas de Plantas/farmacologia , Inibidores da Tripsina/farmacologia , Animais , Fabaceae/química , Larva/efeitos dos fármacos , Larva/enzimologia , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Mariposas/enzimologia , Mariposas/crescimento & desenvolvimento , Tripsina/metabolismo
11.
PLoS Negl Trop Dis ; 14(4): e0008190, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32267851

RESUMO

Mycetoma is a neglected chronic and granulomatous infection primarily associated with the fungal pathogen Madurella mycetomatis. Characteristic of this infection is the formation of grains. However, the processes leading to grain formation are not known. In this study, we employed a proteomic approach to characterise M. mycetomatis grain formation in Galleria mellonella larvae and map the processes leading to grain formation over time. For this, at 1 day, 3 days and 7 days post-inoculation, proteins from grains and hemolymph were extracted and analysed by label-free mass spectrometry. A total of 87, 51 and 48 M. mycetomatis proteins and 713, 997, 18 G. mellonella proteins were found in grains on day 1, 3 and 7 post-inoculation respectively. M. mycetomatis proteins were mainly involved in cellular metabolic processes and numerous enzymes were encountered. G. mellonella proteins were primarily involved in the nodulation process. The proteins identified were linked to nodulation and grain formation and four steps of grain formation were identified. The results of this proteomic approach could in the future be used to design novel strategies to interfere with mycetoma grain formation and to combat this difficult to treat infection.


Assuntos
Larva/crescimento & desenvolvimento , Madurella/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , Mariposas/microbiologia , Micetoma/patologia , Animais , Modelos Animais de Doenças , Larva/microbiologia , Proteômica
12.
Arch Insect Biochem Physiol ; 104(3): e21676, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32323892

RESUMO

The gut microbiota plays an important role in pheromone production, pesticide degradation, vitamin synthesis, and pathogen prevention in the host animal. Therefore, similar to gut morphology and digestive enzyme activity, the gut microbiota may also get altered under plant defensive compound-induced stress. To test this hypothesis, Dendrolimus superans larvae were fed either aconitine- or nicotine-treated fresh leaves of Larix gmelinii, and Lymantria dispar larvae were fed either aconitine- or nicotine-treated fresh leaves of Salix matsudana. Subsequently, the larvae were sampled 72hr after diet administration and DNA extracted from larval enteric canals were employed for gut microbial 16S ribosomal RNA gene sequencing (338 F and 806 R primers). The sequence analysis revealed that dietary nicotine and aconitine influenced the dominant bacteria in the larval gut and determined their abundance. Moreover, the effect of either aconitine or nicotine on D. superans and L. dispar larvae had a greater dependence on insect species than on secondary plant metabolites. These findings further our understanding of the interaction between herbivores and host plants and the coevolution of plants and insects.


Assuntos
Aconitina/farmacologia , Microbioma Gastrointestinal/efeitos dos fármacos , Mariposas/microbiologia , Nicotina/farmacologia , Animais , Bactérias/classificação , Bactérias/genética , Larix , Larva/efeitos dos fármacos , Larva/microbiologia , Mariposas/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Folhas de Planta , RNA Ribossômico 16S , Salix
13.
Arch Insect Biochem Physiol ; 104(3): e21684, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32329117

RESUMO

The Indian meal moth Plodia interpunctella is a pest of stored products worldwide. Plant-derived essential oils with insecticidal activity could be safe products to control this species. The scarce information about the mode of action of most plant-derived products limits their use for the control of insect pests. Here, we demonstrate that an essential oil distilled from Lippia turbinata ("poleo") has insecticidal activity on P. interpunctella larvae. Furthermore, we performed a comprehensive characterization of P. interpunctella neuroendocrine system, in comparison with other lepidopteran species.


Assuntos
Lippia/química , Mariposas/efeitos dos fármacos , Óleos Vegetais/toxicidade , Animais , Inseticidas , Larva/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Mariposas/fisiologia , Sistemas Neurossecretores
14.
Arch Virol ; 165(4): 989-991, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32170393

RESUMO

This work identified a novel rhabdo-like virus in a Chinese black cutworm (Agrotis ipsilon), which we tentatively named "Agrotis ipsilon virus" (AIpsV). The complete genome of AIpsV is 15,454 nucleotides in length and contains seven open reading frames, collectively encoding more than 160 amino acids. The AIpsV genome is predicted to encode three structural proteins, nucleoprotein (N), glycoprotein (G), and large polymerase protein (L), and four unknown proteins. Phylogenetic analysis revealed that the AIpsV clusters with Wuhan ant virus and Hubei rhabdo-like virus 1 within the rhabdo-like virus clade. The level of expression of AIpsV genes was found to be higher in the pupal and adult stages than in the egg and larval stages.


Assuntos
Genoma Viral , Vírus de Insetos/genética , Mariposas/virologia , Animais , Sequência de Bases , Vírus de Insetos/classificação , Vírus de Insetos/isolamento & purificação , Larva/crescimento & desenvolvimento , Larva/virologia , Mariposas/crescimento & desenvolvimento , Fases de Leitura Aberta , Filogenia , Proteínas Virais/genética , Sequenciamento Completo do Genoma
15.
Am Nat ; 195(4): 616-635, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32216670

RESUMO

A key assumption of epidemiological models is that population-scale disease spread is driven by close contact between hosts and pathogens. At larger scales, however, mechanisms such as spatial structure in host and pathogen populations and environmental heterogeneity could alter disease spread. The assumption that small-scale transmission mechanisms are sufficient to explain large-scale infection rates, however, is rarely tested. Here, we provide a rigorous test using an insect-baculovirus system. We fit a mathematical model to data from forest-wide epizootics while constraining the model parameters with data from branch-scale experiments, a difference in spatial scale of four orders of magnitude. This experimentally constrained model fits the epizootic data well, supporting the role of small-scale transmission, but variability is high. We then compare this model's performance to an unconstrained model that ignores the experimental data, which serves as a proxy for models with additional mechanisms. The unconstrained model has a superior fit, revealing a higher transmission rate across forests compared with branch-scale estimates. Our study suggests that small-scale transmission is insufficient to explain baculovirus epizootics. Further research is needed to identify the mechanisms that contribute to disease spread across large spatial scales, and synthesizing models and multiscale data are key to understanding these dynamics.


Assuntos
Baculoviridae/patogenicidade , Interações Hospedeiro-Patógeno , Mariposas/virologia , Animais , Transmissão de Doença Infecciosa , Florestas , Larva/virologia , Modelos Teóricos , Mariposas/crescimento & desenvolvimento
16.
J Insect Sci ; 20(2)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32219450

RESUMO

In the Antheraea pernyi multicapsid nucleopolyhedrovirus (AnpeNPV)-based expression vector system, the frequency of homologous recombination events between wild-type AnpeNPV DNA and the transfer vector is low, resulting in a small amount of recombinant virus. Previous reports have indicated that linearized baculovirus DNA can increase the proportion of recombinant virus relative to the total progeny. To improve the recombination efficiency, we constructed a linearized derivative of AnpeNPV, referred to as AnpeNPVPhEGFP-AvrII, in which egfp flanked by AvrII restriction sites was located at the polyhedrin locus and driven by the polyhedrin promoter. Linear AnpeNPV DNA was obtained by the treatment of AnpeNPVPhEGFP-AvrII genomic DNA with AvrII endonuclease. The infectivity and recombinogenic activity between the linearized and circular viral DNA were evaluated by quantitative real-time polymerase chain reactions. We demonstrated that the linearized AnpeNPV DNA produced only small numbers of infectious budded viruses, accounting for approximately 4.5% of the budded virus production of wild-type AnpeNPV DNA in A. pernyi pupae. However, the linearized AnpeNPV DNA substantially increased recombinant virus production after cotransfection with an appropriate transfer vector; relative abundance of the recombinant virus was approximately 5.5-fold higher than that of the wild-type AnpeNPV DNA in A. pernyi pupae. The linearization of AnpeNPV DNA will facilitate the purification of recombinant viruses using the AnpeNPV-based expression vector system and the construction of an AnpeNPV-based bacmid system.


Assuntos
DNA Viral/análise , Genoma Viral , Mariposas/microbiologia , Nucleopoliedrovírus/genética , Animais , Mariposas/crescimento & desenvolvimento , Pupa/crescimento & desenvolvimento , Pupa/microbiologia
17.
Arch Insect Biochem Physiol ; 104(1): e21666, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32112466

RESUMO

Chitin deacetylase (CDA) is a hydrolytic enzyme that modifies chitin into chitosan in the body of insects. In this study, we obtained a full-length complementary DNA sequence (MsCDA1) from the oriental armyworm Mythimna separata by high-throughput sequencing. MsCDA1 is 1,952 bp long and includes 1,620 bp open reading frame encoding 539 amino acids. Analysis by quantitative real time polymerase chain reaction showed that MsCDA1 expression was higher at the adult stage than at earlier developmental stages. MsCDA1 was expressed in all larval tissues examined, in which the highest expression level was found in the midgut. The RNA interference (RNAi) suppressed MsCDA1 expression levels at 12, 24, and 48 hr after injection of double-stranded RNA (1-4 µg per larva) specific to MsCDA1. Under RNAi condition, CDA enzyme activity was significantly reduced and changes an ultramicroscopic structure of M. separata peritrophic matrix especially in its microfibrillar organization exhibiting loose network. In contrast, the surface of the peritrophic matrix was relatively smooth and well organized at control or low RNAi conditions. Moreover, RNAi of MsCDA1 expression impaired larval growth and development, occasionally leading to larval death. These results demonstrate that MsCDA1 plays a crucial role in maintaining peritrophic matrix integrity in M. separata.


Assuntos
Amidoidrolases/genética , Mariposas/enzimologia , Amidoidrolases/metabolismo , Sequência de Aminoácidos , Animais , Quitina/metabolismo , Trato Gastrointestinal/ultraestrutura , Larva/enzimologia , Larva/genética , Larva/crescimento & desenvolvimento , Mariposas/genética , Mariposas/crescimento & desenvolvimento , Interferência de RNA , Análise de Sequência de DNA
18.
Arch Insect Biochem Physiol ; 104(2): e21670, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32196735

RESUMO

Most immune effectors are inducible to microbial pathogen infection while some are already present to act as prophylactic immunity against as yet unseen infection. This study identified secretory phospholipase A2 (sPLA2 ) as a prophylactic factor in diamondback moth, Plutella xylostella. Western blotting using a polyclonal antibody raised against other lepidopteran sPLA2 reacted specifically with ∼25 kDa protein, which was present at approximately 0.4 mM in the plasma of naïve larvae. Interrogation of P. xylostella transcriptomes revealed an open-reading frame for sPLA2 (Px-sPLA2 ), exhibiting high homology with other Group III sPLA2 s. Px-sPLA2 was expressed in all developmental stages. In the larval stage, bacterial challenge induced its expression in hemocytes and fat body but not in gut or epidermis. RNA interference (RNAi) suppressed Px-sPLA2 messenger RNA level and sPLA2 activity in plasma. An inhibition zone assay showed that Px-sPLA2 exhibited antibacterial activities against different species, because specific RNAi knockdown impaired the activity. The RNAi treatment also suppressed the cellular immune response assessed by hemocyte nodule formation and humoral immune response assessed by antimicrobial peptide gene expression. Finally, benzylideneacetone (BZA, a specific sPLA2 inhibitor) treatment inhibited plasma sPLA2 activity of naive larvae in a dose-dependent manner. An addition of BZA significantly increased the bacterial virulence of an entomopathogen, Bacillus thuringiensis. These results suggest that Px-sPLA2 is an immune-associated factor of P. xylostella and its relatively high level of concentration in the plasma of naive larvae strongly suggests its role as a prophylactic factor in defending against pathogens at early infection stages.


Assuntos
Imunidade Celular , Imunidade Humoral , Proteínas de Insetos/genética , Mariposas/genética , Mariposas/imunologia , Fosfolipases A2 Secretórias/genética , Sequência de Aminoácidos , Animais , Eicosanoides , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Larva/genética , Larva/crescimento & desenvolvimento , Larva/imunologia , Mariposas/crescimento & desenvolvimento , Fosfolipases A2 Secretórias/química , Fosfolipases A2 Secretórias/metabolismo , Filogenia , Alinhamento de Sequência
19.
J Insect Sci ; 20(1)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32061083

RESUMO

Plant tannins, polyphenolic plant secondary metabolites are involved in important chemical defense processes in plants. In this study, tannic acid was used as the standard of plant tannins to determine the effects on nutritional indices and activities of glutathione S-transferases (GSTs), cytochrome P450 monooxygenase (CYP450), carboxylesterase (CarE), and acetylcholinesterase (AChE) in fourth-instar larvae of Hyphantria cunea (Drury) by feeding on an artificial diet containing tannic acid under different treatments. We found that tannic acid significantly affected the digestive capacity and food utilization rate of H. cunea larvae. A tannic acid concentration of less than 2.0% promoted feeding and the utilization of undesirable food by H. cunea larvae, while inhibitory effects were observed at high concentrations (>2.5%). Tannic acid had a significant effect on the activity of detoxification enzymes and AChE in H. cunea larvae in concentration-dependent and time-dependent manners (P < 0.05). These results provide new insights into the potential mechanisms underlying detoxification in H. cunea larvae against tannic acid in host plants.


Assuntos
Mariposas/efeitos dos fármacos , Taninos/farmacologia , Acetilcolinesterase/metabolismo , Fenômenos Fisiológicos da Nutrição Animal , Animais , Carboxilesterase/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Glutationa Transferase/metabolismo , Inativação Metabólica , Larva/efeitos dos fármacos , Larva/enzimologia , Mariposas/enzimologia , Mariposas/crescimento & desenvolvimento
20.
J Chem Ecol ; 46(3): 299-307, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32060667

RESUMO

Generalist insect herbivores may regulate nutrient balance in their diets, including the incorporation of carbohydrates as well as proteins. However, secondary metabolites, including tannins, are likely to interact with dietary protein:carbohydrate ratios in insect herbivores. We investigated the effects of protein:carbohydrate ratios, tannin, and the interaction between macronutrient ratios and tannin on the performance of the gypsy moth Lymantria dispar. We designed a 6 X 3 factorial experiment, with six protein:carbohydrate ratios and three tannin concentrations. We monitored the development time and size of gypsy moths on the different diets. We conducted 4th stadium feeding trials to measure consumption, digestibility, and overall efficiency of ingestion/digestion. Gypsy moths fed a diet containing a 1:1 protein:carbohydrate ratio without tannin grew larger and developed faster than those fed a 1:2 protein:carbohydrate ratio diet. Increasing protein in the diet above the 1:1 protein:carbohydrate ratio (i.e. 2:1 or 7:1) did not have a significant effect on gypsy moth growth or development. Approximate digestibility was greatest in treatments with a low protein:carbohydrate ratio (1:2). Gypsy moths grew faster and larger on no-tannin diets than those with tannin in the diet. However, the specific concentration of tannin did not affect growth. The resulting interaction between protein:carbohydrate ratio and tannin showed that there may be a trade-off between development time and efficiency of food assimilation. We also found that feeding gypsy moth larvae an optimal protein:carbohydrate ratios may be more important for tolerating tannin than the amount of protein ingested alone.


Assuntos
Carboidratos da Dieta/análise , Proteínas na Dieta/análise , Herbivoria , Mariposas/fisiologia , Taninos/metabolismo , Animais , Dieta , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Nutrientes/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA