Common Cutworm Research Articles

LEDランプを用いた電灯照明によるヤガ類の防除技術－露地アスパラガス栽培でのハスモンヨトウによる被害低減効果に及ぼす黄色パルス光の照射方向の影響－

LEDランプを用いた電灯照明によるヤガ類の防除技術－露地アスパラガス栽培でのハスモンヨトウによる被害低減効果に及ぼす黄色パルス光の照射方向の影響－

Comparative study of two thioredoxins from common cutworm (Spodoptera litura): Cloning, expression, and functional characterization

Thioredoxins (Trxs) are a ubiquitous family of antioxidant enzymes that are involved in protecting organisms against various oxidative stresses. Here, we cloned and characterized two thioredoxins, named SlTrx1 and SlTrx2, from the common cutworm Spodoptera litura. SlTrx1 and SlTrx2, respectively, consist of 988 and 606 bp full-length cDNA with 318 and 447 bp open reading frames encoding 106 and 149 amino acid residues. Furthermore, the N-terminal region of SlTrx2 contains a predicted mitochondrial localization signal (33 amino acids). A phylogenetic relationship analysis revealed that SlTrx1 is in the cytosolic thioredoxin Trx1 cluster, whereas SlTrx2 is in the mitochondrial thioredoxin Trx2 cluster. Recombinant SlTrx1 (14 kDa) and SlTrx2 (16 kDa), expressed in baculovirus-infected insect Sf9 cells, demonstrated insulin disulfide reductase activity at the same optimum temperature and pH value of 35 °C and 7.0, respectively, in vitro. During S. litura development, we found that SlTrx1 and SlTrx2 had similar transcript expression patterns and were constitutively expressed in the epidermis, fat body, and midgut, with the highest expression occurring in the sixth-instar larval stage in the epidermis and midgut. In addition, both SlTrx1 and SlTrx2 mRNA were up-regulated in S. litura after injection with H2O2, cumene hydroperoxide, indoxacarb, and metaflumizone. These results suggest that SlTrx1 and SlTrx2 function as potent antioxidant enzymes, and provide a molecular basis for the roles SlTrx1 and SlTrx2 during development and the oxidative stress response of S. litura.

Identification and functional characterization of sex pheromone receptors in the common cutworm (Spodoptera litura).

Male moths can finely discriminate the sex pheromone emitted by conspecific females from similar compounds. Pheromone receptors, expressed on the dendritic membrane of sensory neurons housed in the long trichoid sensilla of antennae, are thought to be associated with the pheromone reception. In this study, we identified and functionally characterized 4 pheromone receptors from the antennae of Spodoptera litura (Lepidoptera: Noctuidae). A tissue distribution analysis showed that the expression of the 4 SlituPRs was restricted to antennae. In addition, SlituOR6 and SlituOR13 were specifically expressed in male antennae whereas SlituOR11 and SlituOR16 were male-biased. Functional investigation by heterologous expression in Xenopus oocytes revealed that SlituOR6 was specifically tuned to the second major pheromone component, Z9,E12-14:OAc, SlituOR13 was equally tuned to Z9,E12-14:OAc and Z9-14:OAc, with a small response to the major pheromone component Z9,E11-14:OAc, SlituOR16 significantly responded to the behavioral antagonist Z9-14:OH, whereas SlituOR11 did not show response to any of the pheromone compounds tested in this study. Our results provide molecular data to better understand the mechanisms of sex pheromone detection in the moth S. litura and bring clues to investigate the evolution of the sexual communication channel in closely related species through comparison with previously reported pheromone receptors in other Spodoptera species.

Insect pests of groundnut (Arachis hypogaea L.), nature of damage and succession with the crop stages

Thirty six species of insect pests were found to infest the different growth stages of groundnut crop at Gazipur, Bangladesh during the rabi seasons of 2008-09 and 2009-010. Among the recorded pest species, the hairy caterpillar, Spilarctia obliqua ( Walker); common cutworm, Spodoptera litura F.; jassid, Empoasca terminalis Distant ; leaf miner, Stomopteryx nerteria M. and leaf roller, Anersia ephippias (Meyr.) were considered as the major pests, while the rests were of minor importance on the basis of their population densities/plant, nature and extent of damage and yield reductions. Most of the major and minor pests infested during the vegetative to pre-maturity stages (45-95 DAS) and the maximum infestation occurred during pod formation and pod filling stages (50- 80 DAS) of the crop in both the years. DOI: http://dx.doi.org/10.3329/bjar.v39i2.20429 Bangladesh J. Agril. Res. 39(2): 273-282, June 2014

A new cell line from the fat body of Spodoptera litura (Lepidoptera, Noctuidae) and detection of lysozyme activity release upon immune stimulation.

A new cell line, designated NIAS-SL64, was established from the fat body of the fifth instar larvae of the common cutworm Spodoptera litura. NIAS-SL64 cells grew as spindle-shaped and non-adherent cells in the insect-specific cell culture medium MGM-450 supplemented with 10% fetal bovine serum. Criterions for the establishment of the NIAS-SL64 cell line is spindle shape and length (30~90 μm) stabilized after 100 passages. The doubling time of the cells was 24 h at 25°C. Lipopolysaccharide significantly stimulated the release of lysozyme activity by NIAS-SL64 cells. Lysozyme is one of the components of the innate immunity and plays important role as lytic enzyme in infection. Lysozyme activity released from NIAS-SL64 would be a marker for immune response. The released lysozyme activity critically depends on morphology of the cells and would be a criterion of the establishment of the cell line. Lysozyme activity was suppressed in a dose-dependent manner by the immunosuppressive agent cyclosporin A.

Peroxiredoxin 5 from common cutworm (Spodoptera litura) acts as a potent antioxidant enzyme.

In this study, we describe the cloning and characterization of a Prx from the common cutworm Spodoptera litura (SlPrx5). The SlPrx5 cDNA contains an open reading frame of 477 bp encoding a predicted protein of 159 amino acid residues, 16.902 kDa, and an isoelectric point of 7.68. Furthermore, the deduced amino acid sequence of the SlPrx5 cDNA showed 86% identity to Papilio xuthus Prx5, 72% to Aedes aegypti Prx5, and 64-67% to other insect Prxs. A phylogenetic analysis further revealed that the deduced amino acid sequence of SlPrx5 groups within the atypical 2-Cys Prx cluster. Recombinant SlPrx5 (20 kDa) purified from baculovirus-infected insect cells was found to reduce H2O2 in the presence of electrons donated by dithiothreitol and protect super-coiled DNA from damage by metal-catalyzed oxidation in vitro. During S. litura development, SlPrx5 is constitutively expressed in the epidermis, fat body, and midgut, with the highest expression occurring in the sixth-instar larval stage in the fat body and midgut. Additionally, SlPrx5 mRNA expression was up-regulated after injection with H2O2, cumene hydroperoxide, indoxacarb, and metaflumizone. A disc diffusion assay indicated that recombinant SlPrx5 can play a functional role in protecting cells from oxidative stress in vivo. These results provide insight into the role of SlPrx5 during development and the oxidative stress response of S. litura.

Identification of soybean MYC2-like transcription factors and overexpression of GmMYC1 could stimulate defense mechanism against common cutworm in transgenic tobacco.

MYC2 is a basic helix-loop-helix Leu zipper transcription factor (TF). Here, 22 putative soybean MYC-like TFs were identified bioinformatically. Of these TFs, seven MYC2-like genes without introns were isolated and characterized. All seven GmMYCs displayed transactivation activity in yeast cells. Six genes (excepting GmMYC3) were expressed in the roots, stems, leaves, flowers, and seed wall but not in the developing seeds and up-regulated after insect feeding. The GmMYC1 transgenic tobacco rejected common cutworm (CCW, Spodoptera litura Fabricius) more strongly and lost less leaf area than the control (2.94±2.36 vs 7.84±4.63cm(2)). The average relative growth rate of CCW feeding on transgenic tobacco leaves was lower than on control tobacco leaves (136±60 vs 271±76%). These results indicated that GmMYC could stimulate the defense mechanism against insects in plants.

Expression, subcellular localization and protein‑protein interaction of four isoforms of EcR/USP in the common cutworm

Ecdysone receptor (EcR) and ultraspiracle (USP) form heterodimers to mediate ecdysteroid signaling during molting and metamorphosis. Various EcR/USP heterodimers have been reported. However, it is unclear what kind of EcR/USP combination is adopted by lepidopteran insects during the larval-pupal metamorphosis and whether the EcR/USP heterodimer varies among different tissues. To address these questions, two isoforms of each EcR and USP were cloned from the common cutworm, their messenger RNA expression patterns were examined by real-time quantitative polymerase chain reaction in different tissues during the larval-pupal metamorphosis and in the midgut in response to hormonal induction. Furthermore, their subcellular localization and protein-protein interaction were explored by transient expression and far-western blotting, respectively. All the four genes were significantly up-regulated in prepuae and/or pupae. The expression profiles of EcRB1 and USP1 were nearly identical to each other in the epidermis, fat body and midgut, and a similar situation also applied to EcRA and USP2. The three genes responded to 20-hydroxyecdysone (20E) induction except for USP2, and USP1 could be up-regulated by both 20E and juvenile hormone. The four proteins mainly localized in the nucleus and the nuclear localization was promoted by 20E. The protein-protein interaction between each EcR and USP was found in vitro. These results suggest that two types of EcR/USP heterodimer (EcRA/USP2 and EcRB1/USP1) may exist simultaneously in the common cutworm, and the latter should play more important roles during the larval-pupal metamorphosis. In addition, the types of EcR/USP heterodimer do not vary in the tissues which undergo histolysis and regeneration during metamorphosis.

Transcriptome analysis of soybean lines reveals transcript diversity and genes involved in the response to common cutworm (Spodoptera litura Fabricius) feeding

The interaction between soybeans and the destructive common cutworm insect is complicated. In this paper, the time course of induced responses to common cutworm was characterized in two soybean lines, and the results showed that the induced resistance peaked at different times in the resistant (WX) and susceptible (NN) soybean lines. Two sets of transcriptome profiles from the WX and NN lines at the peak of their induced resistance were compared using microarray analysis. In total, 827 and 349 transcripts were differentially expressed in the WX and NN lines, respectively, with 80 probes common regulated and seven regulated in the opposite direction. All common- and unique-regulated genes were grouped into 10 functional categories based on sequence similarity searches, which showed that most of the genes were related to stress and defence responses. qRT-PCR analysis of 22 genes confirmed the results of the microarray analysis. The spatiotemporal expression patterns of the six genes revealed the consistency of systemic expression levels with the timing of the resistance response observed in the bioassay experiments. In summary, we described the conceptual model of induced resistance in two soybean lines and provided the first large-scale survey of common cutworm-induced defence transcripts in soybean.

Complete mitochondrial genome of the common cutworm Spodoptera litura (Lepidoptera: Noctuidae)

We determined the complete mitochondrial genome of the common cutworm Spodoptera litura (Lepidoptera: Noctuidae), which is one of the most destructive polyphagous insect pests worldwide. The genome is 15,383 bp in length (GenBank accession number: KF701043) with an A + T content of 81.08%, and contains 37 typical animal mitochondrial genes (13 protein-coding genes, 2 rRNA genes and 22 tRNA genes) with the typical arrangement found in Lepidoptera. All the protein-coding genes (PCGs) start with ATN start codon except for cox1, which begins with CGA. Eight PCGs stop with complete termination codons (TAA or TAG), whereas five PCGs use incomplete stop codon T. The A + T-rich region is located between rrnS and trnM with a length of 326 bp and an A + T content of 93.87%, and harbors three tandem repeat elements.

Physiological effect of mild thermal stress and its induction of gene expression in the common cutworm, Spodoptera litura

Heat shock protein (Hsp) and its cognate protein (Hsc) play important roles in helping insects survive extreme temperatures. However, high level of Hsp expression usually brings negative physiological effects on organisms. The mechanism of this trade-off is unclear. In this study, a lepidopteran insect, the common cutworm Spodoptera litura, was stressed at different temperatures, and the impact on both thermotolerance and fecundity was examined. The mRNA levels of four Hsp/Hscs (Hsp90, Hsc90, Hsp70 and Hsc70) and two ecdysone receptors (EcRs, EcRA and EcRB1) in different stresses and during the larval–pupal metamorphosis were determined. The results revealed that the pre-acclamation at mild stress increased the thermotolerance but decreased the egg production in adults. During the stress process, the mRNA levels of all the Hsp/Hsc and ecdysone receptor genes were significantly up-regulated. The two Hsp/Hsc70s and EcRs revealed consistent expression profiles with each other during the larval–pupal metamorphosis. Co-immunoprecipitation and Western blotting analysis indicated that Hsp/Hsc70 interacted with EcRs. RNAi of Hsc70 decreased the mRNA levels of two 20E-induced genes such as E74B and E75. Hsp70 transferred from the cytoplasm to nucleus in response to cold stress. These data together suggest that Hsp/Hsc70 might be involved in the regulation of 20E signaling, and the protein–protein interaction between Hsp/Hsc70 and EcRs probably act as a bridge mediating the trade-off between high thermotolerance and physiological defects.

愛知県におけるイラクサギンウワバおよびハスモンヨトウの薬剤感受性の差異

愛知県におけるイラクサギンウワバおよびハスモンヨトウの薬剤感受性の差異

Variation in GmAOS1 promoter is associated with soybean defense against insect attack

Soybean (Glycine max L.) displays considerable variation in its resistance to insects. Characterization and application of insect resistance genes in soybean germplasm may be a sustainable and economical approach to soybean production. In this study, we demonstrated that the gene encoding allene oxide synthase (GmAOS1) was associated with soybean defense against the common cutworm (CCW, Spodoptera litura Fabricius) attack through gene expression analysis and association analysis. The expression of GmAOS1 in stems and leaves of resistant accessions was higher than that of susceptible accessions in the undamaged soybean plant. After CCW feeding, the transcript levels of GmAOS1 increased and reached their maximal values sooner in the leaves of resistant accession than they did in susceptible accession. The genomic sequence of GmAOS1 was re-sequenced and aligned in 184 soybean accessions. Forty-three SNPs/Indels were found in its promoter region and only one single nucleotide polymorphism was found in its coding region. Association analysis showed that GmAOS1 promoter polymorphisms were significantly associated with three soybean defense indexes. GmAOS1_19 was the most resistant allele associated with soybean resistance to CCW. Two elements (TATCCAT/C motif and Box II-like sequence) located at genomic regions upstream of GmAOS1_21 were significantly associated with compensatory regrowth of soybean plants. Gene expression analysis indicated that the accessions containing different GmAOS1 promoters and with different CCW resistance grades showed different expression levels of GmAOS1. Our data indicate that variation in GmAOS1 promoter is associated with soybean defense against CCW attack.

Constitution of resistance to common cutworm in terms of antibiosis and antixenosis in soybean RIL populations

Common cutworm (CCW; Spodoptera litura Fabricius) is a major leaf-feeding pest in Asia. The focus of this study was to explore the genetic mechanism for resistance to CCW in terms of antibiosis and antixenosis through mapping QTL (Quantitative trait locus/loci) in soybean using two recombinant inbred line populations. Larva weight (LW) and pupa weight (PW) were evaluated as indicators for antibiosis and damaged leaf percentage as the indicator for antixenosis to CCW. The obvious transgressive segregation indicated a complementary genetic status between the parents. The genetic structure for antibiosis and antixenosis was similar, about 51.1–75.7 % of the phenotypic variation (PV) accounted for by genetic variation, where 42.2–60.3 %, or the majority, was explained by the collective unmapped minor QTL. And, 0–6 additive QTL each explained 0.0–11.8 % in a total of 0.0–27.4 % of PV, and 0–3 epistatic QTL pairs each explained 0.0–7.6 % in a total of 0.0–14.0 % of PV. However, the detected QTL compositions for antibiosis and antixenosis were quite different with only one QTL qCCW10_1 shared by both antibiosis and antixenosis with 8.9–11.8 and 4.7 % contribution to PV, respectively. Within antibiosis between LW and PW, the detected QTL overlapped (r = 0.53–0.78). Among the detected QTL, qCCW6_1, qCCW10_1 and qCCW12_2 were the major contributors to antibiosis, and qCCW10_1, qCCW10_2 and qCCW12_1 the major contributors to antixenosis. Since only some major QTL could be used for marker-assisted breeding, the main concern is how to use the large amount of undetected minor QTL.

Seasonality of the common cutworm Spodoptera litura in a soybean ecosystem

Seasonal occurrence of the common cutworm Spodoptera litura (Fab.) (Lepidoptera: Noctuidae) moths captured in synthetic sex pheromone traps and associated field population of eggs and larvae in soybean were examined in India from 2009 to 2011. Male moths of S. litura first appeared in late July or early August and continued through October. Peak male trap catches occurred during the second fortnight of September, which was within soybean reproductive stages. Similarly, the first appearance of S. litura egg masses and larval populations were observed after the first appearance of male moths in early to mid-August, and were present in the growing season up to late September to mid-October. The peak appearance of egg masses and larval populations always corresponded with the peak activity of male moths recorded during mid-September in all years. Correlation studies showed that weekly mean trap catches were linearly and positively correlated with egg masses and larval populations during the entire growing season of soybean. Seasonal means of male moth catches in pheromone traps during the 2010 and 2011 seasons were significantly lower than the catches during the 2009 season. However, seasonal means of the egg masses and larval populations were not significantly different between years. Pheromone traps may be useful indicators of the onset of numbers of S. litura eggs and larvae in soybean fields.

Cloning, expression and chitin‐binding activity of two peritrophin‐like protein genes in the common cutworm, Spodoptera litura

Insect midgut secretes a semi-permeable peritrophic membrane (PM), which plays important roles in protecting the midgut and helping with food digestion. The lepidopteran larvae produce type 1 PM, which is degraded when insects develop into the metamorphic stages. However, the underlying mechanism is unclear. In the present study, two peritrophin-like proteins (peritrophin-57 and 37) were identified from the midgut expression sequence tag library and transcriptome of the common cutworm, Spodoptera litura. The temporal and spatial expression patterns and responses to the induction of 20-hydroxyecdysone (20E) and starvation were examined by real-time quantitative polymerase chain reaction according to their common sequence region. The chitin-binding activity was also studied using a competitor, calcofluor. The open reading frames are 1 554 and 1 020 bp, respectively. They shared four highly conserved peritrophin-A domains and were expressed only in the midgut rather than in the other tissues, including fat body, epidermis, Malpighian tube and hemolymph. Their transcriptional expression could only be detected at the larval stages rather than in eggs, prepupae, pupae and adults. The purified protein of peritrophin-37 bound to chitin in a dose-dependent manner. These results indicate that the two proteins are peritrophins, the structural components of PM. In addition, the messenger RNA levels of the two peritrophins were significantly down-regulated by 20E injection, whereas feeding/starvation had no effect on the expression. These findings suggest that the increase of 20E titer may be an important factor which controls the degradation of PM during metamorphosis.

Insecticide Susceptibility of Three Species of Cutworm (Lepidoptera: Noctuidae) Pests of Grapes

Climbing cutworms in the genus Abagrotis are economically important pests of grapes in the Okanagan Valley of British Columbia (BC). Grapes are recently introduced into many areas of the region, and the association between crop and pest is new and still evolving. This has led to limited information being available on pest management strategies, including the evaluation of chemical controls compatible with local production practices. Few insecticides are currently registered in Canada for cutworm control on grapes, and our study was initiated to provide information on the efficacy of potential control materials. We were also interested in the relative susceptibilities of the three most common cutworm species attacking grape buds in BC--Abagrotis orbis (Grote), Abagrotis reedi Buckett, and Abagrotis nefascia (Smith). Dose-response bioassays with nine insecticides were conducted on neonate larvae using Bok Choy leaf disks, and on fourth-instar larvae using diet incorporation. There were considerable differences in the toxicity of insecticides within species for neonates and fourth instars. For some materials, the relative toxicity to neonates and fourth instars were not correlated. Response to insecticides among the three species showed variation as well, and correct identification of the species complex present in individual locations is important in choosing the best available control material.

Population and damage projection of Spodoptera litura (F.) on peanuts (Arachis hypogaea L.) under different conditions using the age‐stage, two‐sex life table

The common cutworm, Spodoptera litura (Fabricus), is the most serious pest of peanuts in Taiwan. In order to devise an ecology-based and cost-effective control program, we collected life table data and consumption rates from larvae reared indoors at a constant temperature of 25°C, or outdoors at ambient temperatures during the spring and fall of 2010. A computer simulation was then used to project the population growth and damage potential of S. litura on peanuts. Laboratory-reared S. litura individuals produced 3548 eggs/female, whereas those reared outdoors produced 3452 and 3072 eggs/female in the spring and fall, respectively. The intrinsic rate of increase was 0.1828, 0.1308 and 0.1545 day(-1), and the net consumption rate was 194.0, 132.2 and 166.6 cm(2) larva(-1) at 25°C, in spring and fall, respectively. Population projection showed a faster growth and higher damage potential of S. litura in the fall. Population projections based on life tables and stage-specific consumption rates can reveal the stage structure and damage potential of the pest population. Our results showed that monitoring data obtained by using pheromone traps were not in concordance with the damage potential of the pest population. This approach offers a promising tool for pest management.

Insect Pests Of Soybean (Glycine Max L.), Their Nature Of Damage And Succession With The Crop Stages

Thirty nine species of insect pests were found to infest soybean crop at their different growth stages in Noakhali region of Bangladesh during January to May, 2010 and 2011. Among the recorded pest species, six species namely, hairy caterpillar, Spilarctia obliqua (Walker); leaf roller, Lamprosema indicata F; common cutworm, Spodoptera litura F; pod borer, Helicoverpa armigera (Hubner); stem fly, Ophiomyia phaseoli (Tryon) and white fly; Bemisia tabaci Genn. were considered as the major pests while the rests were of minor importance on the basis of population densities per plant, nature and extent of damages, and yield reductions. Most of the major and minor pests appeared in the crop during vegetative to flowering stages (30-50 Days after sowing) and the maximum insect population and their infestation occurred during flowering and pod formation stages of the crop throughout the study period. J. Asiat. Soc. Bangladesh, Sci. 39(1): 1-8, June 2013 DOI: http://dx.doi.org/10.3329/jasbs.v39i1.16027

De novo characterization of transcriptome and gene expression dynamics in epidermis during the larval-pupal metamorphosis of common cutworm

Larval cuticle is degraded and replaced by the pupal counterpart during larval-pupal metamorphosis in the holometabolous insects. In addition to the extrinsic transformation, the epidermis goes through significant changes at molecular levels. To elucidate the intrinsic mechanism of epidermal metamorphosis, the dynamics of chitin content in the cuticle was examined in an important agricultural lepidopteran, the common cutworm, and the transcriptome was analyzed using Illumina sequencing technology. Gene expression profiles during the metamorphosis were further studied by both the digital gene expression (DGE) system and real-time quantitative PCR. The results showed that the chitin content decreased in prepupae and then increased in pupae. A total of 58 million sequencing reads were obtained and assembled into 70,346 unigenes. Over 9000 unigenes were identified to express differentially during the transformation process. As compared with the 6th instar feeding larvae, the most significant changes took place in the proteasome and metabolic pathways in prepupae and pupae, respectively. The cytochrome P450s, VHDLs, chitinase, serine protease and genes involved in sex pheromone biosynthesis changed their mRNA levels remarkably. Three chitinolytic enzymes (chitinase, β-N-acetylglucosaminidase and chitin deacetylase) showed distinct mRNA expression patterns, the former two enzymes revealed the highest expression in prepupae, however the latter one showed its climax mRNA level in pupae. The gene expression patterns suggest that chitinase and β-N-acetylglucosaminidase may be responsible for the degradation of larval cuticles, whereas chitin deacetylase may help to degrade the pupal counterparts. Gene expression dynamics also implied that the chitin of pupal cuticle might be formed by recycling of the degraded chitin of larval cuticle rather than through de novo synthesis. The 20E-induced nuclear receptors seem to be important factors regulating chitin metabolic enzymes during the cuticle remodeling. Our data provide a comprehensive resource for exploring the molecular mechanism of epidermal metamorphosis in insects.