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1.
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
2.
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
3.
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
4.
Insect Biochem Mol Biol ; 115: 103244, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31560967

RESUMO

Three different pheromone binding proteins (PBPs) can typically be found in the sensilla lymph of noctuid moth antennae, but their relative contributions in perception of the sex pheromone is rarely verified in vivo. Previously, we demonstrated that SlitPBP3 plays a minor role in the sex pheromone detection in Spodoptera litura using the CRISPR/Cas9 system. In the present study, the roles of two other SlitPBPs (SlitPBP1 and SlitPBP2) are further verified using the same system. First, by co-injection of Cas9 mRNA/sgRNA into newly laid eggs, a high rate of target mutagenesis was induced, 51.5% for SlitPBP1 and 46.8% for SlitPBP2 as determined by restriction enzyme assay. Then, the homozygous SlitPBP1 and SlitPBP2 knockout lines were obtained by cross-breeding. Finally, using homozygous knockout male moths, we performed electrophysiological (EAG recording) and behavioral analyses. Results showed that knockout of either SlitPBP1 or SlitPBP2 in males decreased EAG response to each of the 3 sex pheromone components (Z9,E11-14:Ac, Z9,E12-14:Ac and Z9-14:Ac) by 53%, 60% and 63% (for SlitPBP1 knockout) and 40%, 43% and 46% (for SlitPBP2 knockout), respectively. These decreases in EAG responses were similar among 3 pheromone components, but were more pronounced in SlitPBP1 knockout males than in SlitPBP2 knockout males. Consistently, behavioral assays with the major component (Z9,E11-14:Ac) showed that SlitPBP1 knockout males responded in much lower percentages than SlitPBP2 knockout males in terms of orientation to the pheromone, along with reduction in close range behaviors such as hairpencil display and mating attempt. Taken together, this study provides direct functional evidence for the roles of SlitPBP1 and SlitPBP2, as well as their relative importance (SlitPBP1 > SlitPBP2) in the sex pheromone perception. This information is valuable in understanding mechanisms of sex pheromone perception and may facilitate the development of PBP-targeted pest control techniques.


Assuntos
Comunicação Animal , Antenas de Artrópodes/fisiologia , Proteínas de Transporte/fisiologia , Proteínas de Insetos/fisiologia , Percepção Olfatória , Spodoptera/fisiologia , Animais , Sequência de Bases , Sistemas CRISPR-Cas , Feminino , Masculino , Mutação , Atrativos Sexuais
5.
Chemosphere ; 235: 785-793, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31280047

RESUMO

The aim of this study was to investigate whether zinc supplementation modulates cadmium toxicity in the beet armyworm Spodoptera exigua selected for 135 generations towards cadmium tolerance. To achieve this, larvae originating from three laboratory populations of S. exigua (control strain - C; cadmium-intoxicated for 135 generations strain - Cd, and control strain intoxicated with Cd for 1 generation - CCd) were additionally exposed to zinc in three concentrations (Zn1, 400 µg Zn·g-1 dry mass of food; Zn2; 200 µg Zn·g-1 dry mass of food; Zn3, 100 µg Zn·g-1 dry mass of food). As the markers of toxicity, a life history traits (the duration of L4 and L5 stages), cellular (DNA damage indices) and biochemical parameters (ADP/ATP ratio and ATP and HSP70 concentrations) were chosen. The duration of larval stages of Zn supplemented larvae was prolonged, while cellular and biochemical indicators, in general, appeared to be lower in comparison to the insects from respective reference groups in each laboratory populations. Moreover, the range of the differences depended on zinc concentration in food. We can suspect that zinc supplementation contributed to the protection of S. exigua individuals against negative effects of cadmium intoxication, probably at the cost of growth rate. Significant differences in the response pattern between insects from different laboratory populations indicate that the influence of additional stress factors is dependent on the overall condition of animals and their previous adaptation to other stressors.


Assuntos
Adaptação Fisiológica , Cádmio/toxicidade , Poluentes do Solo/toxicidade , Spodoptera/fisiologia , Zinco/metabolismo , Animais , Antioxidantes/metabolismo , Beta vulgaris , Tolerância a Medicamentos , Proteínas de Choque Térmico HSP70 , Larva/efeitos dos fármacos , Spodoptera/efeitos dos fármacos
6.
Planta ; 250(4): 1281-1292, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31240396

RESUMO

MAIN CONCLUSION: Cyanogenic glycosides present in the seeds of wild lima bean plants are associated with seedling defense but do not affect seed germination and seedling growth. Wild lima bean plants contain cyanogenic glycosides (CNGs) that are known to defend the plant against leaf herbivores. However, seed feeders appear to be unaffected despite the high levels of CNGs in the seeds. We investigated a possible role of CNGs in seeds as nitrogen storage compounds that influence plant growth, as well as seedling resistance to herbivores. Using seeds from four different wild lima bean natural populations that are known to vary in CNG levels, we tested two non-mutually exclusive hypotheses: (1) seeds with higher levels of CNGs produce seedlings that are more resistant against generalist herbivores and, (2) seeds with higher levels of CNGs germinate faster and produce plants that exhibit better growth. Levels of CNGs in the seeds were negatively correlated with germination rates and not correlated with seedling growth. However, levels of CNGs increased significantly soon after germination and seeds with the highest CNG levels produced seedlings with higher CNG levels in cotyledons. Moreover, the growth rate of the generalist herbivore Spodoptera littoralis was lower in cotyledons with high-CNG levels. We conclude that CNGs in lima bean seeds do not play a role in seed germination and seedling growth, but are associated with seedling defense. Our results provide insight into the potential dual function of plant secondary metabolites as defense compounds and storage molecules for growth and development.


Assuntos
Glicosídeos/metabolismo , Phaseolus/química , Imunidade Vegetal , Spodoptera/fisiologia , Animais , Germinação , Herbivoria , Nitrogênio/metabolismo , Phaseolus/crescimento & desenvolvimento , Phaseolus/imunologia , Phaseolus/parasitologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/imunologia , Folhas de Planta/parasitologia , Metabolismo Secundário , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/imunologia , Plântula/fisiologia , Sementes/química , Sementes/crescimento & desenvolvimento , Sementes/imunologia , Sementes/parasitologia
7.
Pest Manag Sci ; 75(10): 2840-2850, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31148397

RESUMO

BACKGROUND: This paper documents farmer perceptions and management practices for fall armyworm (Spodoptera frugiderda J.E. Smith), providing a baseline for the development of sustainable pest management strategies. RESULTS: 91% of farmers correctly identified fall armyworm, and reported it as the most important maize pest during 2016/2017 cropping season, affecting nearly half of cultivated area. Estimated maize yield loss during the season, attributed to fall armyworm was 28%. A majority of farmers (60%) used pesticides for fall armyworm control, along with other cultural/physical practices - hand picking and crushing egg masses/caterpillars (36%), and application of ash/sand in the funnel (19%). Farmers used various pesticide active ingredients, and protective measures were inadequate; >50% of farmers did not use any protective measures while spraying. Significantly more male than female farmers used pesticides (P = 0.05), and the reverse was true for cultural practices. Significant maize yield differences (P = 0.001) were observed by gender, attributed to differences in utilization of production inputs/practices. At least 77% of farmers received and shared agricultural advice, which can be optimized to spread information on fall armyworm management options. CONCLUSION: Increased use of pesticides to manage fall armyworm poses health and environmental risks, besides the high cost for farmers and governments. Research into cultural and indigenous practices used by farmers will offer opportunities for alternative and sustainable management practices. Research efforts should pay attention to gender differences in access to resources and inputs. Tackling fall armyworm at the farm level, and averting yield losses will require integrated messaging addressing other production risks. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Agricultura/métodos , Fazendeiros/psicologia , Percepção , Controle de Pragas/métodos , Spodoptera/fisiologia , Adulto , Animais , Fazendeiros/estatística & dados numéricos , Fazendas , Feminino , Humanos , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino , Pessoa de Meia-Idade , Spodoptera/crescimento & desenvolvimento , Zâmbia
8.
BMC Genomics ; 20(1): 428, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31138111

RESUMO

BACKGROUND: Deciphering the molecular mechanisms mediating the chemical senses, taste, and smell has been of vital importance for understanding the nature of how insects interact with their chemical environment. Several gene families are implicated in the uptake, recognition, and termination of chemical signaling, including binding proteins, chemosensory receptors and degrading enzymes. The cotton leafworm, Spodoptera littoralis, is a phytophagous pest and current focal species for insect chemical ecology and neuroethology. RESULTS: We produced male and female Illumina-based transcriptomes from chemosensory and non-chemosensory tissues of S. littoralis, including the antennae, proboscis, brain and body carcass. We have annotated 306 gene transcripts from eight gene families with known chemosensory function, including 114 novel candidate genes. Odorant receptors responsive to floral compounds are expressed in the proboscis and may play a role in guiding proboscis probing behavior. In both males and females, expression of gene transcripts with known chemosensory function, including odorant receptors and pheromone-binding proteins, has been observed in brain tissue, suggesting internal, non-sensory function for these genes. CONCLUSIONS: A well-curated set of annotated gene transcripts with putative chemosensory function is provided. This will serve as a resource for future chemosensory and transcriptomic studies in S. littoralis and closely related species. Collectively, our results expand current understanding of the expression patterns of genes with putative chemosensory function in insect sensory and non-sensory tissues. When coupled with functional data, such as the deorphanization of odorant receptors, the gene expression data can facilitate hypothesis generation, serving as a substrate for future studies.


Assuntos
Proteínas de Insetos/genética , Spodoptera/genética , Animais , Antenas de Artrópodes/metabolismo , Encéfalo/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Esterases/genética , Esterases/metabolismo , Feminino , Perfilação da Expressão Gênica , Genes de Insetos , Proteínas de Insetos/metabolismo , Masculino , Família Multigênica , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Spodoptera/enzimologia , Spodoptera/metabolismo , Spodoptera/fisiologia , Percepção Gustatória
9.
J Insect Sci ; 19(3)2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31115473

RESUMO

Recent studies on polyandry evolution have revolutionized our understanding of sexual selection. Therefore, study on traits in females, such as sensory perception and remating strategies, is expected to disclose a greater role of sexual selection in female evolution. Here, we tested how bodyweights of both sexes affected female and male remating behavior in Spodoptera litura (Fabricius, 1775) (Lepidoptera: Noctuidae). Results show most (74.4%; unmated virgin females may be sexually immature) females and males mated the first time in the second scotophase after eclosion. In the subsequent scotophase, 41.9% once-mated females and 94.1% once-mated males mated the second time with a novel virgin mate. Analyses indicate that female remating probability significantly increased with the increase of her own and the second male's bodyweight but decreased with the increase of the first male's bodyweight, while bodyweights of both sexes have no significant effect on male remating probability. Considering the nature of the low level of polyandry (two times on average) and last male precedence in S. litura, we propose that 1) females are more choosy when remating, from which females will benefit indirectly by sequential mate comparison and remate to replace sperm from the previous mates with those from higher quality mates, and 2) males will generally like to remate with any possible females, from which males will gain direct benefit by siring more offspring. The outcome of polyandry rate is likely to be the result of male investment × female choice interactions.


Assuntos
Peso Corporal , Comportamento Sexual Animal , Spodoptera/fisiologia , Animais , Feminino , Masculino
10.
PLoS One ; 14(4): e0215749, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31034480

RESUMO

Maize farmers in sub-Saharan Africa recently experienced unusual damage in their farms, attributed to the fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith). This pest was first recorded in Africa in 2016, but detailed information on its distribution and damage and farmer's response in invaded areas are largely lacking. In this study, we determined FAW distribution, genetic diversity, host plants, crop damage, and farmers' responses. S. frugiperda was recorded in the 10 regions of Cameroon. Average percentage of infested plants and damage severity (on a scale of 1 to 5) were lowest-20.7 ± 7.4% and 2.1 ± 0.1 respectively-in the Sahelian regions and greatest-69.0 ± 4.3% and 3.1 ± 0.1 respectively-in the Western Highlands. Altitude did not influence FAW incidence and severity and its larvae infrequently co-occurred with maize stemborers on the same plants, suggesting possible direct and/or indirect competition between the two groups of maize pests. In response to this new threat to maize production, farmers have opted for the application of synthetic pesticides. Although our experiments were not designed to determine pesticide efficacy, as parameters such as time since application were not considered, our observations suggest lack of a drastic effect on S. frugiperda infestations on maize. There were two haplotypes of FAW co-occurring in Cameroon corresponding to the rice and corn strains and separated by 1.7% sequence divergence, which does not support the existence of cryptic species. S. frugiperda larvae were also recorded on Sorghum bicolor (L.) Moench (10.6%), Solanum tuberosum L. (2.8%), Ipomoea batatas (L.) Lam. (1.9%), Saccharum officinarum L (0.8%), Phaseolus vulgaris L. (0.4%) and Gossypium hirsutum L. (1.9%). This study show that two strains are present in all agroecological zones in Cameroon, and probably in neighboring countries of central Africa sharing the same agroecologies. Management options should therefore consider the use of specific natural enemies and an informed decision of intervention based on strain capture and damage threshold, to avoid pesticide resistance that may arise from inadequate use of chemicals. Further studies should also be undertaken to assess the response of the two S. frugiperda strains to biopesticides and botanical insecticides.


Assuntos
Spodoptera/patogenicidade , Animais , Camarões , Genoma de Inseto , Interações Hospedeiro-Parasita/efeitos dos fármacos , Interações Hospedeiro-Parasita/genética , Resistência a Inseticidas/genética , Filogenia , Doenças das Plantas/parasitologia , Spodoptera/genética , Spodoptera/fisiologia , Zea mays/efeitos dos fármacos , Zea mays/parasitologia
11.
PLoS One ; 14(4): e0216082, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31022256

RESUMO

The elicitor Hrip1 isolated from necrotrophic fungus Alternaria tenuissima, could induce systemic acquired resistance in tobacco to enhance resistance to tobacco mosaic virus. In the present study, we found that the transgenic lines of Hrip1-overexpression in wild type (WT) Arabidopsis thaliana were more resistant to Spodoptera exigua and were early bolting and flowering than the WT. A profiling of transcription assay using digital gene expression profiling was used for transgenic and WT Arabidopsis thaliana. Differentially expressed genes including 40 upregulated and three downregulated genes were identified. In transgenic lines of Hrip1-overexpression, three genes related to jasmonate (JA) biosynthesis were significantly upregulated, and the JA level was found to be higher than WT. Two GDSL family members (GLIP1 and GLIP4) and pathogen-related gene, which participated in pathogen defense action, were upregulated in the transgenic line of Hrip1-overexpression. Thus, Hrip1 is involved in affecting the flower bolting time and regulating endogenous JA biosynthesis and regulatory network to enhance resistance to insect.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/parasitologia , Resistência à Doença , Flores/fisiologia , Doenças das Plantas/imunologia , Doenças das Plantas/parasitologia , Spodoptera/fisiologia , Animais , Arabidopsis/imunologia , Proteínas de Arabidopsis/genética , Ciclopentanos/metabolismo , Regulação da Expressão Gênica de Plantas , Oxilipinas/metabolismo , Fotoperíodo , Plantas Geneticamente Modificadas , Reprodutibilidade dos Testes
12.
PLoS One ; 14(4): e0208966, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30947263

RESUMO

The introduction and establishment of fall armyworm (Spodoptera frugiperda) in Africa presents a major threat to agriculture in that continent and potentially to the entire Eastern Hemisphere. The species is subdivided into two subpopulations called the R-strain and C-strain that differ in their distribution on different plant hosts. This means that the scope of the economic risk posed by invasive fall armyworm is influenced by whether one or both strains are present. Multiple studies have found mitochondrial markers diagnostic of the two strains throughout Africa but there is substantial disagreement with a nuclear strain marker that makes conclusions about strain composition uncertain. In this study the issue of whether both strains are present in Africa was tested by an assay that can detect strain-biased mating behaviors. Western Hemisphere fall armyworm consistently showed evidence of strain-specific assortative mating in the field that was not found in surveys from multiple locations in Africa. The absence of strain mating biases and the disagreements between the strain diagnostic genetic markers indicates that the R-strain is rare (<1% of the population) or absent in Africa. Instead, it appears that the African fall armyworm populations are dominated by two groups, the C-strain and the descendants of interstrain hybrids. These results suggest that plant hosts associated with the R-strain may not be at high risk of fall armyworm infestation in Africa.


Assuntos
Produtos Agrícolas/parasitologia , Doenças das Plantas/parasitologia , Spodoptera/fisiologia , África , Agricultura , Animais , Polimorfismo de Nucleotídeo Único , Reprodução , Spodoptera/genética
13.
Insect Mol Biol ; 28(6): 773-784, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-30980443

RESUMO

In insects, lipid digestion is controversial because insects have no bile salts to solubilize dietary lipids. One hypothesis is that a secretory type of phospholipase A2 (sPLA2 ) provides lysophospholipid (LPL) from dietary phospholipids (PLs). We identified a sPLA2 , Se-sPLA2 , in beet armyworm, Spodoptera exigua, that hydrolyses PLs at sn-2. Our goal was to investigate its role in lipid digestion. Se-sPLA2 was expressed in the entire alimentary canal. Incubating the isolated midgut in a cell culture medium led to secretion of Se-sPLA2 and other proteins. Ex vivo RNA interference (RNAi) of Se-sPLA2 expression in isolated midgut culture led to significantly decreased Se-sPLA2 secretion into the medium. Feeding double-stranded RNA specific to Se-sPLA2 to larvae suppressed sPLA2 activity in gut contents. A recombinant Se-sPLA2 was susceptible to benzylideneacetone (BZA), a specific PLA2 inhibitor. After feeding BZA to larvae, we recorded significant decreases in gut content sPLA2 activity, body growth and total haemolymph lipid contents. RNAi against Se-sPLA2 resulted in reduced digestibility. Addition of a specific LPL, 1-palmitoyl-sn-glycero-3-phosphocholine, to BZA-treated larvae rescued digestibility and larval growth. These results strongly bolster our hypothesis that Se-sPLA2 secreted from the midgut acts in lipid digestion by providing necessary LPL to solubilize dietary neutral lipids.


Assuntos
Digestão , Proteínas de Insetos/metabolismo , Metabolismo dos Lipídeos , Fosfolipases A2 Secretórias/metabolismo , Spodoptera/fisiologia , Sequência de Aminoácidos , Animais , Proteínas de Insetos/química , Intestinos/fisiologia , Larva/enzimologia , Larva/crescimento & desenvolvimento , Larva/fisiologia , Fosfolipases A2 Secretórias/química , Spodoptera/enzimologia , Spodoptera/crescimento & desenvolvimento
14.
J Insect Sci ; 19(2)2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30817821

RESUMO

It is recognized that the behavioral rhythms of organisms are controlled by the circadian clock, while the reverse direction, i.e., whether changes in physiology and behavior react to the internal rhythms, is unclear. Cryptochromes (CRYs) are photolyase-like flavoproteins with blue-light receptor function and other functions on circadian clock and migration in animals. Here, we cloned the full-length cDNA of CRY1 and CRY2 in Spodoptera litura (Fabricius, 1775) (Lepidoptera: Noctuidae). Sl-CRYs show high similarity to orthologs from other insects, and their conserved regions contain a DNA photolyase domain and a FAD-binding seven domain. The expression levels of both genes were relatively low during the larval stage, which increased during the pupal stage and then peaked at the adult stage. The expression of Sl-CRY1 and Sl-CRY2 showed differences between males and females and between scotophase and photophase. Further, our study demonstrated that copulation has a significant effect on the expression of Sl-CRYs. More interestingly, the changes in the expression of Sl-CRY1 and Sl-CRY2 due to copulation showed the same trend in both sexes, in which the expression levels of both genes in copulated males and females decreased in the subsequent scotophase after copulation and then increased significantly in the following photophase. Considering the nature of the dramatic changes in reproductive behavior and physiology after copulation in S. litura, we propose that the changes in the expression of Sl-CRYs after copulation could have some function in the reproductive process.


Assuntos
Copulação , Criptocromos/genética , Expressão Gênica , Proteínas de Insetos/genética , Spodoptera/fisiologia , Sequência de Aminoácidos , Animais , Criptocromos/química , Criptocromos/metabolismo , Feminino , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Larva/crescimento & desenvolvimento , Larva/metabolismo , Masculino , Filogenia , Pupa/genética , Pupa/crescimento & desenvolvimento , Pupa/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Alinhamento de Sequência , Spodoptera/genética , Spodoptera/crescimento & desenvolvimento , Spodoptera/metabolismo
15.
Environ Sci Pollut Res Int ; 26(14): 14426-14434, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30868456

RESUMO

Insect physiology is affected by the presence of toxins in the surrounding environment of insects as well as their food sources. The objective of this study was to determine the effect of heavy metal exposure to two low concentrations (50 µg/g and 150 µg/g) of lead (Pb) and zinc (Zn) through artificial diet to the larvae on biological parameters of Asian armyworm (Spodoptera litura Fabricius) (Lepidoptera: Noctuidae). Both Pb and Zn, even at low concentrations, had relatively high toxic effects on S. litura larvae (P < 0.01). S. litura larval weight and length suffered the maximum reduction when the larvae were fed on diet mixed with the high Pb concentration (150 µg/g) tested compared to the other treatments. At the same Pb concentration (150 µg/g), values of larva growth index, pupa growth index, immature growth index, standardized growth index, and fitness index were 4.66, 7.33, 7.82, 5.35, and 10.00 times lower, respectively, than those of control. At the same Zn concentration (150 µg/g), values of larval growth index, pupal growth index, immature growth index, standardized growth index, and fitness index were 5.61, 3.00, 3.04, 3.23, and 9.24 times lower, respectively, than those of control. The survival rate of S. litura larvae was also lower (12.5%) when the larvae were fed on diet mixed with Pb at 150 µg/g after 10 days of observation. Overall, the presence of those heavy metals in the environment, even at low concentrations, would exert an adverse impact on larvae development of this insect. From this point of view, findings could provide a basis for long-term evaluation of heavy metal risk and its impact on populations of important agricultural pests.


Assuntos
Exposição Dietética , Poluentes Ambientais/toxicidade , Metais Pesados/toxicidade , Spodoptera/fisiologia , Animais , Peso Corporal , Dieta , Hemípteros , Larva/efeitos dos fármacos , Pupa/efeitos dos fármacos , Pupa/crescimento & desenvolvimento , Spodoptera/efeitos dos fármacos
16.
BMC Genomics ; 20(1): 237, 2019 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-30902045

RESUMO

BACKGROUND: Common cutworm (CCW) is highly responsible for destabilizing soybean productivity. Wild soybean is a resource used by breeders to discover elite defensive genes. RESULTS: The transcriptomes of two wild accessions (W11 and W99) with different resistance to CCW were analyzed at early- and late-induction time points. After induction, the susceptible accession W11 differentially expressed 1268 and 508 genes at the early and late time points, respectively. Compared with W11, the resistant accession W99 differentially expressed 1270 genes at the early time point and many more genes (2308) at the late time point. In total, 3836 non-redundant genes were identified in both lines. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that the differentially expressed genes (DEGs) in W99 at the late time point were mostly associated with specific processes and pathways. Among the non-redundant genes, 146 genes were commonly up-regulated in the treatment condition compared with the control condition at the early- and late-induction time points in both accessions used in this experiment. Approximately 40% of the common DEGs were related to secondary metabolism, disease resistance, and signal transduction based on their putative function. Excluding the common DEGs, W99 expressed more unique DEGs than W11. Further analysis of the 3836 DEGs revealed that the induction of CCW not only up-regulated defense-related genes, including 37 jasmonic acid (JA)-related genes, 171 plant-pathogen-related genes, and 17 genes encoding protease inhibitors, but also down-regulated growth-related genes, including 35 photosynthesis-related genes, 48 nutrition metabolism genes, and 28 auxin metabolism genes. Therefore, representative defense-related and growth-related genes were chosen for binding site prediction via co-expression of transcription factors (TFs) and spatial expression pattern analyses. In total, 53 binding sites of 28 TFs were identified based on 3 defense-related genes and 3 growth-related genes. Phosphate transporter PT1, which is a representative growth-related gene, was transformed into soybean, and the transgenic soybean plants were susceptible to CCW. CONCLUSIONS: In summary, we described transcriptome reprograming after herbivore induction in wild soybean, identified the susceptibility of growth-related genes, and provided new resources for the breeding of herbivore-resistant cultivated soybeans.


Assuntos
Variação Genética , Análise de Sequência de RNA , Soja/genética , Spodoptera/fisiologia , Animais , Perfilação da Expressão Gênica , Ontologia Genética , RNA Mensageiro/genética , Soja/imunologia , Fatores de Transcrição/genética
17.
Plant Cell ; 31(3): 687-698, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30760558

RESUMO

Herbivore-induced plant volatiles prime plant defenses and resistance, but how they are integrated into early defense signaling and whether a causal relationship exists between volatile defense priming and herbivore resistance is unclear. Here, we investigated the impact of indole, a common herbivore-induced plant volatile and modulator of many physiological processes in plants, bacteria, and animals, on early defense signaling and herbivore resistance in rice (Oryza sativa). Rice plants infested by fall armyworm (Spodoptera frugiperda) caterpillars release indole at a rate of up to 25 ng*h-1 Exposure to equal doses of exogenous indole enhances rice resistance to S. frugiperda Screening of early signaling components revealed that indole pre-exposure directly enhances the expression of the leucine-rich repeat-receptor-like kinase OsLRR-RLK1 Pre-exposure to indole followed by simulated herbivory increases (i.e. primes) the transcription, accumulation, and activation of the mitogen-activated protein kinase OsMPK3 and the expression of the downstream WRKY transcription factor gene OsWRKY70 as well as several jasmonate biosynthesis genes, resulting in higher jasmonic acid (JA) accumulation. Analysis of transgenic plants defective in early signaling showed that OsMPK3 is required and that OsMPK6 and OsWRKY70 contribute to indole-mediated defense priming of JA-dependent herbivore resistance. Therefore, herbivore-induced plant volatiles increase plant resistance to herbivores by positively regulating early defense signaling components.


Assuntos
Resistência à Doença , Indóis/metabolismo , Oryza/genética , Doenças das Plantas/imunologia , Transdução de Sinais , Spodoptera/fisiologia , Animais , Ciclopentanos/metabolismo , Regulação da Expressão Gênica de Plantas , Herbivoria , Indóis/farmacologia , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Oryza/imunologia , Oryza/parasitologia , Oryza/fisiologia , Oxilipinas/metabolismo , Doenças das Plantas/parasitologia , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas
18.
Plant Physiol ; 179(4): 1822-1833, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30700538

RESUMO

Jasmonic acid (JA) plays an important role in the induction of herbivore resistance in many plants. However, JA-independent herbivore resistance has been suggested. An herbivore-resistance-inducing substance was isolated from Tobacco mosaic virus-infected tobacco (Nicotiana tabacum) leaves in which a hypersensitive response (HR) was induced and identified as loliolide, which has been identified as a ß-carotene metabolite. When applied to tomato (Solanum lycopersicum) leaves, loliolide decreased the survival rate of the two-spotted spider mite, Tetranychus urticae, egg deposition by the same pest, and the survival rate of larvae of the common cutworm Spodoptera litura without exhibiting toxicity against these herbivores. Endogenous loliolide levels increased not only with an infestation by S litura larvae, but also with the exogenous application of their oral secretions in tomato. A microarray analysis identified cell-wall-associated defense genes as loliolide-responsive tomato genes, and exogenous JA application did not induce the expression of these genes. Suppressor of zeaxanthin-less (szl), an Arabidopsis (Arabidopsis thaliana) mutant with a point mutation in a key gene of the ß-carotene metabolic pathway, exhibited the decreased accumulation of endogenous loliolide and increased susceptibility to infestation by the western flower thrip (Frankliniella occidentalis). A pretreatment with loliolide decreased susceptibility to thrips in the JA-insensitive Arabidopsis mutant coronatine-insensitive1 Exogenous loliolide did not restore reduced electrolyte leakage in szl in response to a HR-inducing bacterial strain. These results suggest that loliolide functions as an endogenous signal that mediates defense responses to herbivores, possibly independently of JA, at least in tomato and Arabidopsis plants.


Assuntos
Benzofuranos/metabolismo , Herbivoria , Tabaco/química , Animais , Arabidopsis/efeitos dos fármacos , Benzofuranos/química , Benzofuranos/isolamento & purificação , Carotenoides/metabolismo , Morte Celular , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/parasitologia , Spodoptera/fisiologia , Tetranychidae/fisiologia , Tabaco/virologia , Vírus do Mosaico do Tabaco
19.
Ecotoxicology ; 28(3): 323-332, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30758728

RESUMO

Spodoptera litura is one of the major insect pests of vegetables in Sichuan, China, and it has developed serious resistance to many traditional chemical insecticides. In this present study, S. litura individuals collected from five regions in Sichuan in 2017, which were detected the resistance to bistrifluron. We found that the resistance ratios (RRs) bistrifluron were in the ranges of 15.9- to 77.7-fold, respectively, compared with a laboratory susceptible (Lab-HN) strain. To elucidate the effect of bistrifluron on the life history parameters of S. litura, we established the bistrifluron-susceptible (Bis-UNSEL) and bistrifluron-resistant (Bis-SEL) strains based on the DY field population with the highest RR of 77.7-fold among the all field populations to bistrifluron compared with a laboratory Lab-HN strain. The results show that the Bis-SEL strain developed a 113.8-fold RR while that of the Bis-UNSEL strain was almost equal to that of the Lab-HN strain (with overlapping confidence intervals (CI) of their LC50 values, P < 0.05). Meanwhile, the life span of the egg and pupa stage of the Bis-UNSEL strain was prolonged, and the strain also showed shorter adult duration and lower fecundity. Demographic characteristics, such as the intrinsic rate of increase (r), finite rate of increase (λ) and net reproductive rate (R0) in the Bis-SEL strain were significantly higher than the Bis-UNSEL strain, whereas the mean generation time (T) and gross reproduction rate (GRR) were lower. The results clearly showed that the developing resistance of bistriflueon on S. litura promoted its population growth. Therefore, the present study could provide useful informations for determining potential management methods to prevent the development of bistrifluron resistance in S. litura.


Assuntos
Hidrocarbonetos Halogenados , Resistência a Inseticidas , Inseticidas , Compostos de Fenilureia , Spodoptera/fisiologia , Animais , China , Larva/efeitos dos fármacos
20.
Pest Manag Sci ; 75(8): 2124-2132, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30632285

RESUMO

BACKGROUND: The fall armyworm, Spodoptera frugiperda (J.E. Smith), is the first target pest that has developed resistance to Bt crops across several countries. Leaf tissue and whole plant assays were employed to determine the survival, development, progeny production, and net reproductive rate of all nine possible genotypes of Cry1A.105/Cry2Ab2-dual gene resistant S. frugiperda on non-Bt and MON 89034 maize expressing the Cry1A.105/Cry2Ab2 proteins. RESULTS: The homozygous resistant genotype was highly resistant to Bt plants. Genotypes possessing only Cry2Ab2 resistance alleles (RAs) or two Cry1A.105 RAs only were susceptible to MON 89034 with a functional dominance level (DML ) of 0.0-0.07 on MON 89034 plants. In contrast, genotypes containing two Cry1A.105 plus one Cry2Ab2 RA performed well on Bt plants, with a DML of 0.11-0.78. Significant numbers of survivors on Bt plants were also observed for genotypes containing a single Cry1A.105 RA, or a Cry1A.105 plus one or two Cry2Ab2 RAs, with a DML of 0.0-0.47. CONCLUSIONS: The fitness of individual resistant genes on pyramided Bt plants varied in the dual-gene resistance system. Genotypes containing more Cry1A.105 RAs performed better than those possessing more Cry2Ab2 RAs. The functional dominance level of an individual resistant gene in this system is related to the DML level in its corresponding single-gene system. Data generated from this study should fill gaps in understanding dual-/multiple-gene Bt resistance, as well as providing useful information for refining resistance modeling, improving resistance risk assessment, and developing management strategies for the sustainable use of pyramided Bt maize technology. © 2019 Society of Chemical Industry.


Assuntos
Proteínas de Bactérias/farmacologia , Endotoxinas/farmacologia , Proteínas Hemolisinas/farmacologia , Resistência a Inseticidas , Spodoptera/efeitos dos fármacos , Animais , Genótipo , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/fisiologia , Fenótipo , Plantas Geneticamente Modificadas/química , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Spodoptera/crescimento & desenvolvimento , Spodoptera/fisiologia , Zea mays/química , Zea mays/crescimento & desenvolvimento
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