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2.
Int J Mol Sci ; 22(9)2021 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-34066665

RESUMO

Odorant-binding proteins (OBPs) typically act as transporters of odor molecules and play an important role in insect host location. Here, we identified an OBP in brown planthopper (BPH) Nilaparvata lugens salivary glands via transcriptome sequencing. Real-time quantitative PCR and Western blotting analysis results showed that NlugOBP11 was highly expressed in salivary glands and secreted into rice plant during feeding, suggesting that it assists in BPH feeding on rice. Functional analysis in N. lugens saliva revealed that silencing this gene by RNA interference decreased the BPH stylet performance in the phloem of rice plants, reduced sap sucking, and ultimately led to insect death. Moreover, overexpression of NlugOBP11 in rice protoplasts or Nicotiana benthamiana leaves inhibited the production of defense-related signaling molecule salicylic acid in rice plant. The results demonstrate that NlugOBP11 is not only essential for BPH feeding, but also acts as an effector that inhibits plant defense.


Assuntos
Comportamento Alimentar , Hemípteros/fisiologia , Oryza/parasitologia , Reguladores de Crescimento de Plantas/farmacologia , Receptores Odorantes/metabolismo , Saliva/metabolismo , Sequência de Aminoácidos , Animais , Ciclopentanos/farmacologia , Hemípteros/crescimento & desenvolvimento , Oxilipinas/farmacologia , Receptores Odorantes/química , Ácido Salicílico/farmacologia , Tabaco/efeitos dos fármacos
3.
J Insect Sci ; 21(2)2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33861348

RESUMO

The potential of the parasitoid Psyllaephagus bliteus Riek for the biological control of the eucalyptus pest Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae) nymphs is high. This research sought to analyze the courtship, male competition, and mating behavior of P. bliteus at the proportions of 1:1 and 2:1 males to female in a Petri dish (5 cm diameter), and to describe the ovary histology of virgin and mated females of this parasitoid. At 1:1, males touch the antennae and thorax-abdomen of females during courtship, but females avoid mate attempts before they are 48 h old. At 2:1, the competition between male parasitoids inhibits mating. The histology of ovaries of virgin and mated P. bliteus females is similar, with two well-defined germarium and vitellarium regions, with oocytes at different developmental stages, including mature ones rich in yolk and with eggshell. A clearer understanding of the reproductive behavior and histology of P. bliteus aids in the use of this parasitoid for the biological control of G. brimblecombei.


Assuntos
Himenópteros/anatomia & histologia , Himenópteros/fisiologia , Comportamento Sexual Animal , Animais , Corte , Feminino , Hemípteros/crescimento & desenvolvimento , Hemípteros/parasitologia , Interações Hospedeiro-Parasita , Controle de Insetos , Masculino , Ninfa/parasitologia , Ovário/anatomia & histologia , Controle Biológico de Vetores
4.
J Insect Sci ; 21(2)2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33822127

RESUMO

Sugarcane spittlebugs are considered important pests in sugarcane crops ranging from the southeastern United States to northern Argentina. To evaluate the effects of climate variables on adult populations of Aeneolamia varia (Fabricius) (Hemiptera: Cercopidae), a 3-yr monitoring study was carried out in sugarcane fields at week-long intervals during the rainy season (May to November 2005-2007). The resulting data were analyzed using the univariate Forest-Genetic method. The best predictive model explained 75.8% variability in physiological damage threshold. It predicted that the main climatic factors influencing the adult population would be, in order of importance, evaporation; evapotranspiration by 0.5; evapotranspiration, cloudiness at 2:00 p.m.; average sunshine and relative humidity at 8:00 a.m. The optimization of the predictive model established that the lower and upper limits of the climatic variables produced a threshold in the population development rate of 184 to 267 adult insects under the agroecological conditions of the study area. These results provide a new perspective on decision-making in the preventive management of A. varia adults in sugarcane crops.


Assuntos
Hemípteros/crescimento & desenvolvimento , Dinâmica Populacional , Saccharum , Animais , Argentina , Inteligência Artificial , Clima , Produtos Agrícolas , Análise Fatorial , Modelos Estatísticos , Controle de Pragas , Sudeste dos Estados Unidos
5.
BMC Plant Biol ; 21(1): 114, 2021 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-33627099

RESUMO

BACKGROUND: The tomato psyllid, Bactericera cockerelli Sulc (Hemiptera: Triozidae), is a pest of solanaceous crops such as tomato (Solanum lycopersicum L.) in the U.S. and vectors the disease-causing pathogen 'Candidatus Liberibacter solanacearum'. Currently, the only effective strategies for controlling the diseases associated with this pathogen involve regular pesticide applications to manage psyllid population density. However, such practices are unsustainable and will eventually lead to widespread pesticide resistance in psyllids. Therefore, new control strategies must be developed to increase host-plant resistance to insect vectors. For example, expression of constitutive and inducible plant defenses can be improved through selection. Currently, it is still unknown whether psyllid infestation has any lasting consequences on tomato plant defense or tomato plant gene expression in general. RESULTS: In order to characterize the genes putatively involved in tomato defense against psyllid infestation, RNA was extracted from psyllid-infested and uninfested tomato leaves (Moneymaker) 3 weeks post-infestation. Transcriptome analysis identified 362 differentially expressed genes. These differentially expressed genes were primarily associated with defense responses to abiotic/biotic stress, transcription/translation, cellular signaling/transport, and photosynthesis. These gene expression changes suggested that tomato plants underwent a reduction in plant growth/health in exchange for improved defense against stress that was observable 3 weeks after psyllid infestation. Consistent with these observations, tomato plant growth experiments determined that the plants were shorter 3 weeks after psyllid infestation. Furthermore, psyllid nymphs had lower survival rates on tomato plants that had been previously psyllid infested. CONCLUSION: These results suggested that psyllid infestation has lasting consequences for tomato gene expression, defense, and growth.


Assuntos
Hemípteros/crescimento & desenvolvimento , Interações Hospedeiro-Parasita/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/genética , Lycopersicon esculentum/imunologia , Lycopersicon esculentum/parasitologia , Imunidade Vegetal/genética , Animais , Regulação da Expressão Gênica de Plantas , Genes de Plantas
6.
J Insect Sci ; 21(1)2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33560362

RESUMO

Laricobius nigrinus (Coleoptera: Derodontidae) Fender and Laricobius osakensis (Coleoptera: Derodontidae) Montgomery and Shiyake have been mass produced by Virginia Tech as biological control agents for the hemlock woolly adelgid (HWA), Adelges tsugae (Hemiptera: Adelgidae) Annand, for the past 15 and 9 yr, respectively. Herein, we describe modifications of our rearing procedures, trends and analyses in the overall production of these agents, and the redistribution of these agents for release to local and federal land managers. Based on these data, we have highlighted three major challenges to the rearing program: 1) high mortality during the subterranean portion of its life cycle (averaging 37% annually) reducing beetle production, 2) asynchrony in estivation emergence relative to the availability of their host HWA minimizing food availability, and 3) unintended field collections of Laricobius spp. larvae on HWA provided to lab-reared larvae complicating rearing procedures. We further highlight corresponding avenues of research aimed at addressing each of these challenges to further improve Laricobius spp. production.


Assuntos
Besouros/fisiologia , Hemípteros/fisiologia , Controle Biológico de Vetores/métodos , Animais , Agentes de Controle Biológico , Besouros/crescimento & desenvolvimento , Hemípteros/crescimento & desenvolvimento , Cicutas (Apiáceas)/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/fisiologia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Virginia
7.
Int J Mol Sci ; 21(24)2020 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-33371331

RESUMO

Many insects are capable of developing two types of wings (i.e., wing polyphenism) to adapt to various environments. Though the roles of microRNAs (miRNAs) in regulating animal growth and development have been well studied, their potential roles in modulating wing polyphenism remain largely elusive. To identify wing polyphenism-related miRNAs, we isolated small RNAs from 1st to 5th instar nymphs of long-wing (LW) and short-wing (SW) strains of the brown planthopper (BPH), Nilaparvata lugens. Small RNA libraries were then constructed and sequenced, yielding 158 conserved and 96 novel miRNAs. Among these, 122 miRNAs were differentially expressed between the two BPH strains. Specifically, 47, 2, 27 and 41 miRNAs were more highly expressed in the 1st, 3rd, 4th and 5th instars, respectively, of the LW strain compared with the SW strain. In contrast, 47, 3, 29 and 25 miRNAs were more highly expressed in the 1st, 3rd, 4th and 5th instars, respectively, of the SW strain compared with the LW strain. Next, we predicted the targets of these miRNAs and carried out Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis. We found that a number of pathways might be involved in wing form determination, such as the insulin, MAPK, mTOR, FoxO and thyroid hormone signaling pathways and the thyroid hormone synthesis pathway. Thirty and 45 differentially expressed miRNAs targeted genes in the insulin signaling and insect hormone biosynthesis pathways, respectively, which are related to wing dimorphism. Among these miRNAs, Nlu-miR-14-3p, Nlu-miR-9a-5p and Nlu-miR-315-5p, were confirmed to interact with insulin receptors (NlInRs) in dual luciferase reporter assays. These discoveries are helpful for understanding the miRNA-mediated regulatory mechanism of wing polyphenism in BPHs and shed new light on how insects respond to environmental cues through developmental plasticity.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Hemípteros/genética , Proteínas de Insetos/metabolismo , MicroRNAs/genética , Asas de Animais/anatomia & histologia , Animais , Perfilação da Expressão Gênica , Hemípteros/anatomia & histologia , Hemípteros/crescimento & desenvolvimento , Proteínas de Insetos/genética , Fenótipo , Transdução de Sinais , Transcriptoma , Asas de Animais/crescimento & desenvolvimento , Asas de Animais/metabolismo
8.
PLoS One ; 15(6): e0234030, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32492065

RESUMO

Diaphorina citri Kuwayama is the most economically important citrus pest which is the primary vector of Candidatus Liberibacter spp. causing citrus greening (huanglongbing, HLB) disease. To better understand the developmental and structural changes of antennae and antennal sensilla in D. citri nymphs, we investigated the antennal morphology, structure and sensilla distribution of the five nymphal stages of D. citri using scanning electron microscopy. The antennae of the five different nymphal stages of D. citri were filiform in shape, which consisted of two segments in the first-, second- and third-instar nymphs; three segments in the fourth- and fifth-instar nymphs. The length of their antennae was significantly increased with the increase of the nymphal instar, as well as the total number of antennal sensilla. Ten morphological sensilla types were recorded altogether. They were the long terminal hair (TH1), short terminal hair (TH2), sensilla trichoidea (ST), cavity sensillum 1 (CvS1), cavity sensillum 2 (CvS2), sensilla basiconica 1-3 (SB1-3), sensilla campaniform (SCA) and partitioned sensory organ (PSO). Also, the distribution of antennal sensilla in each nymphal stage of D. citri was asymmetrical. The SBs only occurred on the antennae of the third-, fourth- and fifth-instar nymphs. Only one CvS2 was found in the third- and fifth-instar nymphs, and one SCA in the fourth- and fifth-instar nymphs, respectively. The possible roles of the nymphal antennal sensilla in D. citri were discussed. The results could contribute to a better understanding of the development of the sensory system, and facilitate future studies on the antennal functions in D. citri nymphs.


Assuntos
Antenas de Artrópodes/anatomia & histologia , Hemípteros/anatomia & histologia , Sensilas/anatomia & histologia , Animais , Antenas de Artrópodes/fisiologia , Hemípteros/crescimento & desenvolvimento , Microscopia Eletrônica de Varredura , Ninfa/anatomia & histologia , Sensilas/fisiologia
9.
J Insect Sci ; 20(3)2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32559297

RESUMO

Wolbachia is a maternally inherited bacterium ubiquitous in insects that has attracted interest as a prospective insect pest-control agent. Here, we detected and characterized Wolbachia in the leafhoppers Matsumuratettix hiroglyphicus (Matsumura) (Cicadellidae: Hemiptera) and Yamatotettix flavovittatus Matsumura (Cicadellidae: Hemiptera), insect vectors of the phytoplasma that cause white leaf disease in sugarcane. The 16S rRNA and wsp gene markers revealed that Wolbachia was not present in the M. hiroglyphicus but naturally occurs in Y. flavovittatus. Additionally, the infection rates in adult leafhoppers ranged from 0 to 100% depending on geographic location. Moreover, Wolbachia was detected in the eggs and first- to fifth-instar nymphs of Y. flavovittatus. A phylogenic tree of Wolbachia indicated that it resided in the monophyletic supergroup B clade and clustered in the Ori subgroup. Furthermore, fluorescence in situ hybridization revealed that Wolbachia localized to the egg apices, randomly distributed in the egg cytoplasm, and was concentrated in the nymph and adult bacteriomes, as well as occasional detection in the thorax and abdomen. To the best of our knowledge, the present study is the first to demonstrate the prevalence of Wolbachia in the leafhopper Y. flavovittatus. The obtained results would provide useful information for the future development of Wolbachia as a biological control agent for the leafhopper vectors.


Assuntos
Hemípteros/microbiologia , Simbiose , Wolbachia/fisiologia , Animais , Feminino , Hemípteros/crescimento & desenvolvimento , Insetos Vetores/crescimento & desenvolvimento , Insetos Vetores/microbiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Óvulo/crescimento & desenvolvimento , Óvulo/microbiologia , Doenças das Plantas/microbiologia , Saccharum/microbiologia
10.
Ecotoxicol Environ Saf ; 200: 110719, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32460046

RESUMO

The insecticidal crystal proteins of Cry2A family from Bacillus thuringiensis (Bt) are important candidate proteins expressed in gene pyramiding Bt crops. A transgenic rice line (T2A-1) harboring a synthetic Cry2A* (Cry2Aa) gene showed effective resistance to some lepidopteran rice pests. As a generalist predator in rice ecosystems, the rove beetle (Paederus fuscipes) can prey on many rice insect pests such as planthoppers. Considering the possible exposure of Cry2Aa to P. fuscipes through tritrophic food chain, it is necessary to assess the potential risks of T2A-1 rice to this predator. In this study, a tritrophic experiment was conducted to assess the prey-mediated effects of Cry2Aa on P. fuscipes through the T2A-1 rice-Nilaparvata lugens-P. fuscipes food chain. After preying on N. lugens nymphs reared on T2A-1, no accumulated Cry2Aa could be detected in P. fuscipes adults, despite Cry2Aa being detected in N. lugens. In addition, no harmful effects were detected on the life table parameters of P. fuscipes in this tritrophic chain. Additionally, direct exposure to a high dose of purified Cry2Aa protein, representing the worst case scenario, showed no significant adverse effects on the development of P. fuscipes. These results showed that transgenic Cry2Aa rice had no harmful effects on P. fuscipes.


Assuntos
Proteínas de Bactérias/genética , Besouros , Endotoxinas/genética , Proteínas Hemolisinas/genética , Oryza/genética , Plantas Geneticamente Modificadas/efeitos adversos , Animais , Proteínas de Bactérias/análise , Besouros/química , Produtos Agrícolas/genética , Endotoxinas/análise , Cadeia Alimentar , Hemípteros/química , Hemípteros/crescimento & desenvolvimento , Proteínas Hemolisinas/análise , Ninfa/química
11.
Proc Natl Acad Sci U S A ; 117(19): 10246-10253, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32327610

RESUMO

The evolution of insect resistance to pesticides poses a continuing threat to agriculture and human health. While much is known about the proximate molecular and biochemical mechanisms that confer resistance, far less is known about the regulation of the specific genes/gene families involved, particularly by trans-acting factors such as signal-regulated transcription factors. Here we resolve in fine detail the trans-regulation of CYP6CM1, a cytochrome P450 that confers resistance to neonicotinoid insecticides in the whitefly Bemisia tabaci, by the mitogen-activated protein kinase (MAPK)-directed activation of the transcription factor cAMP-response element binding protein (CREB). Reporter gene assays were used to identify the putative promoter of CYP6CM1, but no consistent polymorphisms were observed in the promoter of a resistant strain of B. tabaci (imidacloprid-resistant, IMR), which overexpresses this gene, compared to a susceptible strain (imidacloprid-susceptible, IMS). Investigation of potential trans-acting factors using in vitro and in vivo assays demonstrated that the bZIP transcription factor CREB directly regulates CYP6CM1 expression by binding to a cAMP-response element (CRE)-like site in the promoter of this gene. CREB is overexpressed in the IMR strain, and inhibitor, luciferase, and RNA interference assays revealed that a signaling pathway of MAPKs mediates the activation of CREB, and thus the increased expression of CYP6CM1, by phosphorylation-mediated signal transduction. Collectively, these results provide mechanistic insights into the regulation of xenobiotic responses in insects and implicate both the MAPK-signaling pathway and a transcription factor in the development of pesticide resistance.


Assuntos
Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Resistência a Medicamentos/genética , Regulação da Expressão Gênica , Hemípteros/crescimento & desenvolvimento , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neonicotinoides/farmacologia , Nitrocompostos/farmacologia , Animais , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Sistema Enzimático do Citocromo P-450/genética , Hemípteros/efeitos dos fármacos , Hemípteros/genética , Hemípteros/metabolismo , Inseticidas/farmacologia , Proteínas Quinases Ativadas por Mitógeno/genética , Mutação , Fosforilação , Regiões Promotoras Genéticas
12.
J Appl Microbiol ; 129(2): 400-410, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32043673

RESUMO

AIMS: To isolate and characterize a native strain of Trichothecium roseum infecting the immatures of Pauropsylla buxtoni on fig leaves, to study the morphological features of the isolated strain, then to test the entomopathogenic effect of the isolated strain against the immatures of P. buxtoni on fig leaves. METHODS AND RESULTS: The isolated strain of T. roseum produced pink mycelial growth on culture medium with septate mycelium and conidiophores. It also produced two-celled conidia with elliptical to pyriform shape born at the tip of conidiophores. Molecular characterization of the isolated strain confirmed the identity of the strain as T. roseum. In bioassays, application of conidial suspension of the isolated strain against the 4th instar of P. buxtoni immatures infesting fig leaves showed an obvious entomopathogenic effect of the applied fungus strain against the targeted insect. This effect was exhibited by the death of treated P. buxtoni immatures with the fungus. The dead insects were characterized by the presence of pinkish mycelial growth on the outer surface which is characteristic to the fungus, in addition to the positive isolation of the fungus from internal tissues of treated insects after a proper external disinfection. Moreover, significant differences (at P < 0·018) were obtained between the means of mortality % of P. buxtoni immatures treated with different concentrations of conidial suspension of the fungus. CONCLUSIONS: The overall results confirm the entomopathogenic effect of T. roseum against P. buxtoni immatures infesting fig leaves. Significant mortalities of P. buxtoni immatures were obtained when the different concentrations of the fungus conidial suspension were bio-assessed against the insect. SIGNIFICANCE AND IMPACT OF THE STUDY: The tested strain of T. roseum can be applied as biocontrol agent of P. buxtoni on fig leaves within an integrated control programme to reduce the impact of pest on fig trees.


Assuntos
Ficus/parasitologia , Hemípteros/microbiologia , Hypocreales/patogenicidade , Controle Biológico de Vetores/métodos , Doenças das Plantas/prevenção & controle , Animais , Hemípteros/crescimento & desenvolvimento , Hypocreales/classificação , Hypocreales/citologia , Hypocreales/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/microbiologia , Doenças das Plantas/parasitologia , Folhas de Planta/parasitologia , Esporos Fúngicos/classificação , Esporos Fúngicos/citologia , Esporos Fúngicos/crescimento & desenvolvimento
13.
Gene ; 737: 144446, 2020 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-32035241

RESUMO

The homeotic complex (Hox) gene Ultrabithorax (Ubx) plays pivotal roles in modifying specific morphological differences among the second (T2), the third thoracic (T3), and the first abdomen (A1) segment in several insects. Whether Ubx regulates wing dimorphism and other morphological traits in the delphacid family (order Hemiptera) remains elusive. In this study, we cloned a full-length Ubx ortholog (NlUbx) from the wing-dimorphic planthopper Nilaparvata lugens, and identified two NlUbx isoforms. RNA-interference (RNAi)-mediated silencing of NlUbx in short-winged BPH nymphs significantly induced the development of wing-like appendages from T3 wingbuds, and this effect is likely mediated by the insulin/insulin-like signaling pathway. RNAi knockdown of NlUbx in long-winged BPH nymphs led to a transformation from hindwings to forewings. Additionally, silencing of NlUbx not only dramatically changed the T3 morphology, but also led to jumping defect of T3 legs. First-instar nymphs derived from parental RNAi had an additional leg-like appendages on A1. These results suggest that Ubx plays a role in determining some morphological traits in delphacid planthoppers, and thus help in understanding evolution of morphological characteristics in arthropods.


Assuntos
Hemípteros/genética , Proteínas de Insetos/genética , Asas de Animais/metabolismo , Sequência de Aminoácidos , Animais , Clonagem Molecular , Feminino , Técnicas de Silenciamento de Genes , Hemípteros/crescimento & desenvolvimento , Proteínas de Insetos/química , Masculino , Alinhamento de Sequência , Asas de Animais/crescimento & desenvolvimento
14.
J Agric Food Chem ; 68(1): 117-127, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31820963

RESUMO

Six new quassinoids, named kumulactone F (1), kumulactone G (2), kumulactone H (4), kumulactone I (5), kumulactone J (6), and kumulactone K (7), a pair of undescribed epimers α- and ß-nigakihemiacetal G (3), 15 known quassinoids (8-22), and a mixture of the known compounds α- and ß-neoquassin (23) were separated from the dried stems of the medical plants Picrasma quassioides. The chemical structures of all of the new compounds were established by spectroscopic data analyses (HR-ESI-MS, 1D and 2D NMR spectroscopy, and electronic circular dichroism (ECD)). Biologically, compounds 9 and 21 showed toxicity toward the Asian citrus psyllid Diaphorina citri Kuwayama with potent activity even equal to that of the positive control (Abamectin), compound 11 exhibited an excellent neuroprotective effect against SH-SY5Y cells which were pretreated by H2O2 with potent activity equal to that of the positive control (Trolox), and none of them showed cytotoxic activity toward the HeLa or A549 cell lines (IC50 > 100 µM).


Assuntos
Hemípteros/efeitos dos fármacos , Inseticidas/farmacologia , Fármacos Neuroprotetores/farmacologia , Picrasma/química , Extratos Vegetais/farmacologia , Quassinas/farmacologia , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Hemípteros/crescimento & desenvolvimento , Humanos , Peróxido de Hidrogênio/toxicidade , Inseticidas/química , Neurônios/citologia , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/química , Extratos Vegetais/química , Quassinas/química
15.
Insect Biochem Mol Biol ; 118: 103292, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31811885

RESUMO

Voltage-gated sodium channels (Nav) are essential for electrical signaling in the nervous system. They are also the primary targets of several classes of insecticides including pyrethroids. There is only one sodium channel gene in most insect species, whereas mammals possess at least nine sodium channel genes. Extensive alternative splicing and RNA editing of sodium channel transcripts have been documented in many insect species. However, the functional consequences of these post-transcriptional events have been evaluated only in DmNav and BgNav from Drosophila melanogaster and Blattella germanica, respectively. In this study, we isolated 41 full-length cDNA clones encoding 34 sodium channel (NlNav) variants from a major rice pest, the brown planthopper (Nilaparvata lugens Stål). The 34 NlNav variants represent 24 distinct splicing types based on the usage of nine alternative exons, six of which, including exon b, have been previously reported in other insect species. When expressed in Xenopus oocytes, NlNav variants lacking exon b generated significantly larger sodium currents than variants possessing exon b, suggesting an inhibitory effect of exon b on sodium current expression. A similar effect has been reported for exon b from BgNav. Mutational analysis showed that three conserved amino acid residues encoded by exon b are critical for its inhibitory effect. In addition, mutually exclusive exons k/l contribute to distinct functional properties and channel sensitivity to pyrethroids. Altogether, these results show that alternative splicing generates functional diversity of sodium channels in this insect species and that the role of exon b in regulating neuronal excitability is likely conserved among insect species.


Assuntos
Hemípteros/genética , Proteínas de Insetos/genética , Canais de Sódio Disparados por Voltagem/genética , Processamento Alternativo , Sequência de Aminoácidos , Animais , Sequência de Bases , Éxons , Hemípteros/crescimento & desenvolvimento , Hemípteros/metabolismo , Proteínas de Insetos/metabolismo , Ninfa/crescimento & desenvolvimento , Ninfa/metabolismo , Alinhamento de Sequência , Canais de Sódio Disparados por Voltagem/metabolismo
16.
Dev Biol ; 459(2): 181-193, 2020 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-31812605

RESUMO

Recent studies have demonstrated endocrine roles for the POU domain transcription factor Ventral veins lacking (Vvl) during larval development of holometabolous insects - insects that undergo complete metamorphosis. In this study, the role of Vvl was examined in the milkweed bug, Oncopeltus fasciatus, a hemimetabolous insect. In the embryos, vvl was found to be expressed in the presumptive prothoracic glands. When vvl expression was knocked down using RNA interference (RNAi), embryos arrested their development after dorsal closure. Vvl double-stranded RNA (dsRNA)-injected nymphs failed to molt and had reduced expression of the ecdysone response gene, hormone receptor 3 (HR3), the ecdysone biosynthesis genes, disembodied and spook, and the juvenile hormone (JH) response gene, Krüppel homolog 1 (Kr-h1). Injection of 20-hydroxyecdysone rescued the molting phenotype and HR3 expression in vvl knockdown nymphs. In adults, vvl RNAi inhibited egg laying and suppressed the expression of Kr-h1 and vitellogenin in the fat body. Application of JH III or methoprene restored oviposition in vvl knockdown adults, indicating that Vvl regulates JH biosynthesis during reproduction. Thus, Vvl functions as a critical regulator of hormone biosynthesis throughout all developmental stages of O. fasciatus. Our study demonstrates that Vvl is a critical transcription factor involved in JH and ecdysteroid biosynthesis in both hemimetabolous and holometabolous insects.


Assuntos
Ecdisona/biossíntese , Hemípteros/embriologia , Hemípteros/crescimento & desenvolvimento , Hormônios Juvenis/biossíntese , Fatores do Domínio POU/metabolismo , Animais , Ecdisterona/farmacologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/genética , Técnicas de Silenciamento de Genes , Hormônios Juvenis/farmacologia , Fatores de Transcrição Kruppel-Like/genética , Masculino , Muda/efeitos dos fármacos , Muda/genética , Oogênese/efeitos dos fármacos , Oogênese/genética , Fatores do Domínio POU/genética , Interferência de RNA , RNA de Cadeia Dupla/síntese química , Reprodução/genética , Transdução de Sinais/genética , Vitelogeninas/metabolismo
17.
Bull Entomol Res ; 110(3): 303-308, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31559943

RESUMO

The hemlock woolly adelgid (Hemiptera: Adelgidae: Adelges tsugae Annand) is an invasive insect, introduced from Japan to eastern North America, where it causes decline and death of hemlock trees. There is a closely related lineage of A. tsugae native to western North America. To inform classical biological control of A. tsugae in the eastern USA, the density and phenology of three native western adelgid specialist predators, Leucopis argenticollis (Zetterstedt), Le. piniperda (Malloch) (Diptera: Chamaemyiidae), and Laricobius nigrinus Fender (Coleoptera: Derodontidae), were quantified in the Pacific Northwest. Infested branches were collected from western hemlock (Pinaceae: Tsuga heterophylla (Raf.) Sarg.) at four sites around the Puget Sound, Washington and three sites in Oregon. Immature Leucopis were identified to species using DNA barcodes. Leucopis argenticollis was roughly twice as abundant as Le. piniperda. Laricobius nigrinus larvae were more abundant than the two species of Leucopis during the egg stage of the first adelgid generation, but Leucopis were present as feeding larvae during the second adelgid generation when La. nigrinus was aestivating in the soil, resulting in Leucopis being more abundant than La. nigrinus across the entire sampling period. Adelges tsugae and La. nigrinus densities were not correlated, while A. tsugae and Leucopis spp. densities were positively correlated. Leucopis spp. and La. nigrinus densities were negatively correlated. These results support the complementary use of La. nigrinus and the two Leucopis species for biological control of A. tsugae in the eastern USA, and point to the need for further investigation of spatial and temporal niche partitioning among the three predator species.


Assuntos
Besouros/fisiologia , Dípteros/fisiologia , Hemípteros/fisiologia , Controle Biológico de Vetores , Comportamento Predatório , Animais , Besouros/crescimento & desenvolvimento , Código de Barras de DNA Taxonômico , Dípteros/genética , Dípteros/crescimento & desenvolvimento , Hemípteros/crescimento & desenvolvimento , Espécies Introduzidas , Larva , Estágios do Ciclo de Vida , Oregon , Tsuga/parasitologia , Washington
18.
Insect Sci ; 27(1): 58-68, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29676854

RESUMO

"Candidatus Liberibacter solanacearum" (Lso) are phloem-restricted and unculturable Gram-negative bacteria. Presently five haplotypes have been identified worldwide; but only haplotypes A and B are associated with the vector Bactericera cockerelli (Sulc.) in the Americas. Previous studies showed that Lso-infection reduces B. cockerelli reproductive output and that Lso haplotype B is more pathogenic than Lso haplotype A. To understand the interaction of Lso haplotype B and B. cockerelli, the fitness of Lso-free and Lso B-infected insects, and the expression of vitellogenin (BcVg1-like), a gene involved directly in the insect reproduction were analyzed. Statistical differences in the number of eggs oviposited, and the total number of progeny nymphs and adults were found among crosses of insects with or without Lso. Significant differences in sex proportions were found between Lso B-infected and Lso-free crosses: a higher proportion of F1 adult females were obtained from Lso B-infected mothers. A significant reduction of BcVg1-like was observed in crosses performed with Lso B-infected females compared to the Lso-free insects. In female cohorts of different age, a significant reduction of BcVg1-like expression was measured in 7-d-old Lso B-infected females (virgin and mated) compared with 7-d-old Lso-free females (virgin and mated), respectively. The reduction of BcVg1-like transcript was associated with a lower number of developing oocytes observed in female's reproductive systems. Overall, this study represents the first step to understand the interaction of Lso B with B. cockerelli, highlighting the effect of Lso B infection on egg production, BcVg1-like expression, and oocyte development.


Assuntos
Aptidão Genética , Hemípteros/fisiologia , Rhizobiaceae/fisiologia , Vitelogênese , Animais , Hemípteros/genética , Hemípteros/crescimento & desenvolvimento , Hemípteros/microbiologia , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/fisiologia , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Ninfa/fisiologia , Doenças das Plantas/microbiologia
19.
Insect Sci ; 27(4): 756-770, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31240817

RESUMO

The tracheal apical extracellular matrix (aECM) is vital for expansion of the tracheal lumen and supports the normal structure of the lumen to guarantee air entry and circulation in insects. Although it has been found that some cuticular proteins are involved in the organization of the aECM, unidentified factors still exist. Here, we found that mind the gap (Mtg), a predicted chitin-binding protein, is required for the normal formation of the apical chitin matrix of airway tubes in the model holometabolous insect Drosophila melanogaster. Similar to chitin, the Mtg protein was linearly arranged in the tracheal dorsal trunk of the tracheae in Drosophila. Decreased mtg expression in the tracheae seriously affected the viability of larvae and caused tracheal chitin spiral defects in some larvae. Analysis of mtg mutant showed that mtg was required for normal development of tracheae in embryos. Irregular taenidial folds of some mtg mutant embryos were found on either lateral view of tracheal dorsal trunk or internal view of transmission electron microscopy analysis. These abnormal tracheae were not fully filled with gas and accompanied by a reduction in tracheal width, which are characteristic phenotypes of tracheal aECM defects. Furthermore, in the hemimetabolous brown planthopper (BPH) Nilaparvata lugens, downregulation of NlCPAP1-N (a homolog of mtg) also led to the formation of abnormal tracheal chitin spirals and death. These results suggest that mtg and its homolog are involved in the proper organization of the tracheal aECMs in flies and BPH, and that this function may be conserved in insects.


Assuntos
Proteínas de Transporte/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Hemípteros/genética , Proteínas de Insetos/genética , Animais , Proteínas de Transporte/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Matriz Extracelular/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Hemípteros/crescimento & desenvolvimento , Hemípteros/metabolismo , Proteínas de Insetos/metabolismo , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Ninfa/metabolismo , Traqueia/crescimento & desenvolvimento
20.
Insect Mol Biol ; 29(1): 38-47, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31260146

RESUMO

The chitin biosynthesis pathway is an important physiology process in arthropods. However, few microRNAs (miRNAs) involved in the regulation of the chitin biosynthesis pathway in insects have been reported until now. In this study, four groups of samples that either upregulated or downregulated the chitin biosynthesis pathway were collected for deep sequencing, and a total of 15 unique mature miRNAs with significantly different expression levels were found, including 11 known miRNAs and four novel miRNAs. Subsequently, we showed that miR-2703 and its new target gene chitin synthase 1a are important for ecdysone-induced chitin biosynthesis in Nilaparvata lugens, a serious insect pest of rice. The nymphs showed an obvious moulting defect phenotype, lower survival rate and significantly reduced chitin content after miR-2703 feeding or injection. Furthermore, we found that the transcription level of miR-2703 was not repressed by 20-hydroxyecdysone signalling after Broad-Complex (BR-C) double-stranded RNA (dsRNA) injection compared with the repressed levels after green fluorescent protein dsRNA injection, suggesting that the involvement of miR-2703 in the 20-hydroxyecdysone pathway contributes to BR-C activity. miR-2703 regulates the chitin biosynthesis pathway by targeting chitin synthase 1a in response to 20-hydroxyecdysone signalling.


Assuntos
Quitina Sintase/genética , Quitina/biossíntese , Hemípteros/genética , MicroRNAs , Animais , Quitina/genética , Ecdisterona , Hemípteros/enzimologia , Hemípteros/crescimento & desenvolvimento , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Muda/genética , Ninfa/crescimento & desenvolvimento , Interferência de RNA , RNA de Cadeia Dupla , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
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