일부 고주파 음파 처리가 파밤나방(Spodoptera exigua)의 생리변화를 유발시킨다. 이 연구는 초음파( 20 kHz) 처리가 파밤나방 유충 섭식, 용 발육 및 성충 교미행동에 미치는 영향을 분석하였다. 초음파 처리는 5령충의 섭식 활동을 억제시켰다. 특별히 30 kHz 또는 45 kHz 초음파 처리를 받은 유충은 50% 이상의 섭식활동이 감소하였다. 이러한 초음파 처리를 받은 유충은 혈장의 주요 영양물질 함량이 변동되었다. 혈장 단백질은 처리 초음파의 주파수 증가에 따라 감소하였다. 그러나 혈당은 처리 초음파의 주파수 증가에 따라 증가하였다. 지질 함량은 30 kHz 처리까지는 증가하다가 이후 감소하였다. 파밤나방 5령의 혈구, 지방체 및 표피세포의 세 조직은 스트레스 관련 유전자들인 세 종류의 열충격단백질과 apolipophorin III를 발현시켰다. 그러나 초음파를 처리할 경우 일부 스트레스 관련 유전자들의 발현을 크게 억제시켰다. 초음파 처리는 또한 용발육을 억제시켜, 용기간을 연장시키고 성충으로 우화를 현격하게 낮추었다. 끝으로 초음파 처리는 성충의 교미행동을 억제시켜 암컷의 산란력을 뚜렷하게 낮추었다. 이러한 결과는 초음파가 파밤나방의 생리적 스트레스로 작용하고 있다는 것을 제시하고 있다.

This study was conducted to investigate the insecticidal capacity of recombinant baculoviruses to Plutella xylostella and Spodoptera exigua larvae. For recombinant viruses, Bacillus thuringiensis cry1-5 crystal protein gene was introduced into the genome by fusion of polyhedrin-cry1-5 under the control of polyhedrin gene promoter. Recombinant AcPolh5-3006BiKTT and AcPolh5-3006 AvTox2 based on BiKTT and AvTox2, respectively, were constructed under the control of early promoter from Cotesia plutellae bracovirus. Mortality of S. exigua larvae was significantly higher when they fed on cabbage coated with ApEGFP (wild type) over 5.0×106 PIBs/ml. For AcPolh5-3006BiKTT and AcPolh5-3006AvTox2, mortality of P. xylostella and S. exigua larvae was significantly higher when they fed on cabbage coated with recombinant baculoviruses over 5.0×106 PIBs/ml and 1.0×104 PIBs/ml, respectively. The value of LD50 was lower in the treatments with AcPolh5-3006BiKTT (P. xylostella:1.2×106, S. exigua:1.3×104) or AcPolh5-3006AvTox2 (P. xylostella:2.3×106, S. exigua:1.4×104) than the treatments with ApEGFP (P. xylostella: not estimated, S. exigua:5.0×105). Survival time (ST50) of P. sylostella larvae was much shorter at AcPolh5-3006BiKTT (29.6h) than AcPolh5-3006AvTox2 (46.2h) while that of S. exigua larvae was much shorter at AcPolh5-3006AvTox2 (95.1h) than AcPolh5-3006BiKTT (101.9h) or ApEGFp (130.7h). The two recombinant baculoviruses were more effective in S. exigua larvae but slower speed of action.

As the immune reactions in human white blood cells of certain substances from insects to defend it when invaded by immune blood cells is increased. We experiment with changes in the total number of blood cells through the blood cells which increases and decreases, as well as to observe whether the immune response through any route is to evaluate what happens. Hemocyte population was analyzed in the last instar larvae of Spodoptera exigua. Granulocyte and plasmatocyte were predominant (>75%) types of hemocytes, whereas spherulocyte, prohemocyte, and oenocytoid hemocytes were observed in small densities (5~10%). Total hemocyte counts (THCs) were varied among different ages (day1-day5) of the last instar, in which day 3 larvae (L5D3) had the maximal density. Upon bacterial challenge to L5D3 larvae, THC was further enhanced within 2 h and then decreased to background level. This rapid THC increase in response to bacterial challenge was inhibited by injection with dexamethasone (1 ㎍ per larva). However, the addition of arachidonic acid reversed the inhibitory activity of dexamethasone and allowed the larvae to increase THC. This THC increase was mediated by cyclooxygenase products, but not by lipoxygenase products.

Sound treatments have been considered as a non-chemical insect pest control technique. Different frequency and intensity sounds were applied to immune and adult stages to screen any stress sounds to alter physiological processes. At 95 dB, 5,000 Hz and 30,000 Hz were selected to be stress sounds in audible and inaudible sound ranges, respectively. Both stress sounds significantly inhibited larval and pupal development. In biochemical analyses, lipid and sugar levels in plasma signigicantly increased in response to the stress sound treatments. Moreover, a digestive phospholipase A2 enzyme activity in midgut was significantly reduced. In adult stage, ultrasound treatment significantly inhibited mating behavior, which resulted in a reduced fecundity. These stress sounds altered gene expressions of stress-related genes, such as heat-shock proteins and apolipophorin III. This study suggests that extreme sounds play a role in physiological stress factors in S. exigua by altering developmental and reproductive processes.

Spodoptera exigua is a significant polyphagous pest in the greenhouse and open field. Our aim of this study was to evaluate light emitting diodes (LEDs) as the potential attractants against Spodoptera exigua on various wavelengths, light intensity, and light duration. The preference response to S. exigua was investigated by the laboratory and field-scale. The wavelengths of LEDs were composed as follows: blue (470 nm), green (520 nm), yellow (590 nm), red (625 nm) and white (450-620 nm). When the optimal light condition was investigated in the laboratory scale, the all light treatments attracted the highest number of S. exigua at 40 lux intensity and 60 min duration. Based on the wavelengths under optimal light condition, the white LED exhibited the highest attraction rate (91.1%), followed by green (88.9%), blue (81.1%), yellow (63.3%) and red (56.7%), respectively. In comparison with the selected white LED and yellow sticky traps in the field-scale, the white LED (81.3%) was about 16.26 times more attractive than yellow sticky trap (5.0%). These results clearly show that the white LED had the greatest attraction against S. exigua.

Beet armyworm (BAW), Spodoptera exigua (Hübner), is a polyphagous lepidopteran pest mainly distributed in tropical and subtropical regions. BAW are known to migrate long distances to find suitable host plants and environmental condition. The possibility of its overwintering in temperate regions has been suspected. This study was conducted for investigating overwintering and phenology of BAW using by sex pheromone trap in Jeju during 2007 to 2011. BAW was able to overwinter at pupae stage regardless of temperature of winter season in Jeju. The times of BAW caught first on traps were different by surveyed years - early March in 2007, middle March in 2008 and 2011 and early April in 2009 and 2010. The times of BAW caught on trap tended to be more dependent on temperature variation during on November and December than on mean temperature of winter season. The peak season of adults of the overwintering generation was early to middle of May. The results of seasonal periodicity of BAW monitored by sex pheromone trap during 2009 and 2010 indicated that five generations were passed in Jeju. The peak season of 1st generation was on middle of April, 2nd generation on middle of July, 3rd generation on early of August, 4th generation on late of August and 5th generation on middle of September. There were similar patterns by different above sea levels except the season of overwintering generation adults occurrence (March to May).

The aim of this study was to evaluate light emitting diodes (LEDs) as the potential attractants against Spodoptera exigua on various wavelengths, light intensity and light duration, and compared to that of commercial control, flourescent lamp. The phototactic response to S. exigua was tested by single and complex wavelengths. The single wavelengths were composed as follows: blue (470 nm), green (520 nm), yellow (590 nm) and red (625 nm). The complex wavelengths was combined with two single wavelengths, such as blue-green, blue-yellow, blue-red, green-yellow, green-red and yellow-red. When the optimal light condition was investigated, the all light treatments attracted the highest number of S. exigua at 40 lux intensity and 60 min duration. Based on the single wavelengths under optimal light condition, the green LED exhibited the highest attraction rate (88.9%), followed by blue (81.1%), yellow (63.3%) and red (56.7%), respectively. In case of complex wavelengths under same conditions, the bluegreen complex (93.3%) had the significantly highest attractive activity, whereas blue-yellow, blue-red, green-yellow, green-red and yellow-red wavelengths were slightly decreased in comparison with single wavelengths. These data clearly show that blue-green complex had the greatest attraction against S. exigua.

The methanol extracts and essential oils from 9 medicinal plants, Ulmus davidiana var. japonica, Cryptomeria japonica, Hedera rhombea, Prunus mume, Taxus cuspidatal, Paulownia coreana, Kalopanax pictus, Paris verticillata, and Ixeris dentata were tested for their insecticidal activity against larvae of S. exigua by topical application method. And the methanol extracts and essential oils obtained from Paris verticillata and Ixeris dentata were subjected to a screening test for their antifeeding activities and pupation and adult emergence of S. exigua by a leaf-dipping method at a concentration of LC50 value. The methanol extract from the bark of C. japonica, the leaf of H. rhombea and all parts of P. verticillata exhibited potent activity with LC50 of 5.02, 4.21 and 5.46(g/L) 5days after treatment, respectively. But all of the essential oils except for I. dentata with LC50 of 4.92(g/L) had shown high potential insecticidal activity compared to the methanol extracts against S. exigua. And the essential oil from all parts of P. verticillata and I. dentata have shown stronger antifeeding activity than those of methanol extracts against larvae of S. exigua. Also, the methanol extract and essential oil of P. verticillata and I. dentata affected growth pattern showing those of 32.5%, 10.0% of pupation and 27.5%, 10.0% of adult emergence of S. exigua.

Scavenger receptors (SRs) are transmembrane cell surface molecules recognized in apophotic cells, bacteria and lipopolysaccharide. With no physiological information on SRs in insects except SR-CI of Drosophila melanogaster, a putative SR gene was cloned and characterized in Spodoptera exigua. A partial S. exigua SR gene was obtained from hemocyte transcripts and exhibited high homology with type C. Its expression was confirmed in all developmental stages. Among different tissues, S. exigua SR was expressed highly in hemocytes. To confirm change in SR expression by infection, Escherichia coli was injected to fifth instar and RNA was extracted after 10 hours. SR expression in hemocytes of E. coli injected larva was not significantly different from the control but SR expression in fat body of E. coli injected larva was higher than the control. It is expected that SRs of S. exigua are related with immune responses against bacteria such as E. coli. To address its function, S. exigua SR expression was suppressed by double-stranded RNA (dsRNA).

This study analyzed effects of different sound treatments in frequencies and intensities on digestion and immune physiological processes of the beet armyworm, Spodoptera exigua larvae. Without effect on egg hatch, sound treatments with 100-5,000 ㎐ at 95 ㏈ suppressed feeding behavior and inhibited a digestive enzyme activity. In addition, two dimensional electrophoresis of midgut luminal proteins indicated a marked difference of the sound-treated larvae. In response to 5,000 ㎐ at 95 ㏈, larvae showed a significant decrease in hemocyte nodule formation against fungal challenge along with significant suppression in phospholipase A₂ activity in hemocyte and plasma. With increase of sound frequencies, the treated larvae showed an enhanced susceptibility to insecticides. Such sound frequency effect was significantly modulated with different sound intensities. These results suggest that sound treatment may give adverse stress to physiological processes of S. exigua larvae and may be applied to a nonchemical insect pest control.

To response evaluation of high power light emitting diodes (HPLEDs) as potential attractants to the Spodoptera exigua adults, we investigated the attractiveness of specific wavelength, illuminance intensity and light-exposure time, and compared them to the fluorescent. The all light treatments with the 40 lux intensity attracted the significantly highest number of S. exigua. The optimal light-exposure time exhibited the highest attraction rate at the 60 min. When the attraction and repellent rate in the optimal conditions to the S. exigua was surveyed, the white HPLED exhibited the highest attraction rate (91.1%), whereas the red HPLED exhibited the most repellent rate (33.3%). When evatuated of illuminance efficiency with fluorescent as control, white and red HPLED were found to be 9.14 and 10.34 times more efficient than fluorescent. These data clearly show that both the 40 lux intensity and the 60 min light-exposure time by using the white HPLED was the most suitable for attraction of the S. exigua.

This study was conducted to investigate the insecticidal capacity of several recombinant baculoviruses to P. xylostella and S. exigua larvae. NeuroBactrus was constructed as follows: the cry1-5 of Bacillus thuringiensis 2385-1 was inserted into Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) genome by fusion of polyhedrin-cry1-5-polyhedrin under the control of polyhedrin gene promoter, and insect-specific neurotoxin from the scorpion Androctonus australis (AaIT) under the control of early promoter from Cotesia plutellae bracovirus was introduced by fusion of orf603 partial fragment in the opposite direction of polyhedrin gene, respectively. Other recombinant baculoviruses derived from the NeuroBactrus - NBt-DelA (deleted AaIT), NBt-Del5 (deleted cry1-5), and NBt-DelA5 (deleted AaIT and cry 1-5) - were manufactured in serial passages in vitro. The data were analyzed by SPSS. The value of LC50 was lower when P. xylostella larvae fed on cabbage coated with NeuroBactrus (4068.4) than when it fed on cabbage coated with AcMNPV (4.5x106). Survival time (ST50) of P. xylostella larvae (2.54days) was shorter when it fed on cabbage coated with NeuroBactrus than when it fed on cabbage coated with other recombinant baculoviruses (7.54days, 7.68days, and 8.26days) and AcMNPV (9.67days). S. exigua larvae presented the same results.

The aim of this research was to demonstrate whether generalist-feeding caterpillars of Spodoptera exigua (Hübner) regulate their nutrient intake when faced with nutritionally variable food conditions. Six, chemically-defined diets were prepared that differed in the composition of protein and digestible carbohyrate:42% protein with 0% carbohydrate by dry mass(p42:c0), p35:c7, p28:c5.6, p7:c35, p5.6:c28 and p0:42. A total of 288 newly-ecdysed final instar(5th) caterpillars were collected and assigned randomly into 7 food pairing treatments, in which they were allowed to choose between two diet block:one with high P:C ratio and the other with low ratio [1) p42:c0 vs. p0:c42, 2) p42:c0 vs. p7:c35, 3) p35:c7 vs. p0:c42, 4) p35:c7 vs. p7:c35, 5) p35:c7 vs. p5.6:c28, 6) p28:c5.6 vs. p7:c35 and 7) p28:c5.6 vs. p5.6:c28]. Various aspects of food intake and larval performance variables were measured for each insect, including larval survival, stadium duration, pupal mass and body lipid composition. Results showed that the intake of protein and carbohydrate self-composed by caterpillars in all treatments converged to a point in a bivariate nutrient plot and the ratio of protein to carbohydrate averaged over these converging intake points was close to 1:1. This indicates that S. exigua caterpillars have capacity to balance their nutrient intake by defending their species-specific ‘intake target’ despite the differences in amount and proportion of nutrients available in each food choice treatment.

Based on Drosophila model, Toll and Imd signals have regared as central intracellular pathways in insect immune cells in response to various pathogens. Current insect genome studies have identified the corresponding orthologs in other insets. This study reports two immune signaling genes, Se-Toll-1 and Se-Relish-1, and suggests Toll and Imd pathways in the hemocytes of Spodoptera exigua. Partial Se-Toll-1 and Se-Relish-1 share high sequence homologies with known Toll and Relish genes of lepidopteran and dipteran species. Their expressions were detected from all developmental stages. In larval stage, there two genes were expressed in all tested tissues including hemocytes. Real time quantitative RT-PCR indicates that expression of both genes were highly up-regulated by bacterial and fungal infections. Various antimicrobial peptides (AMPs) were expressed in the hemocytes of S.exigua, in which their expressions appeared to be controlled by Se-Toll-1 and Se-Relish-1. However, Se-Toll-1 and Se-Relish-1 were proved to controlled different AMP genes from their RNA interference assays. These results suggest Toll and Imd signals in the hemocytes of S. exigua.

Antimicrobial peptides (AMPs) are a group of immune proteins that protect the host from microial infection. Gallerimycin is one of the AMPs most commonly found in Galleria mellonella and Spodoptera frugiperda. In this paper, we found Gallereimycin in Spodoptera exigua by expressed sequence tag library 0analysis. The gallerimycin of S. exigua gene is 332 bp long and the predicted open reading frame contains 75 amino acids with a signal peptide. After removing signal peptide, S. exigua gallrimycin was estimated to be 5.9 kDa and pI at 8.53. The gallerimycin of S. exigua shared maximum sequence homology with that of S. frugiperda. In naive S. exigua larvae, not much gene expression was detected, but strongly induced in fat body and hemocytes following immune challenge with entomopathogenic bacteria and fungus. A recombinant gallerimycin was prepared using a bacterial expression system and showed significant antibacterial and antifungal activities. RNA interference using double stranded RNA could knock down the expression of gallerimycin and significantly suppressed immune capacity.

To clarify the molecular mechanism of metamorphosis, we analyzed the Broad-Complex (BR-C) gene in the beet armyworm, Spodoptera exigua. We obtained a partial BR-C sequence from a pyrosequencing cDNA library. The BR-C of S. exigua was expressed only in the final larval instar, at which its expression was clearly detected in the epidermis. A treatment of a juvenile hormone analog, pyriproxyfen, inhibited larval-pupal metamorphosis and suppressed the BR-C expression. The hormonal treatment also inhibited expression of two storage protein genes that were usually expressed during a final larval instar. RNA interference of the BR-C using its double strand RNA suppressed BR-C expression and inhibited the larval-pupal metamorphosis. These results suggest that the BR-C is critical to induce larval-pupal metamorphosis of S. exigua.

Sodium-potassium-chloride co-transporter (NKCC) is a membrane bound channel protein that plays a prominent role in a variety of epithelial absorptive, secretory processes and a direct role in cell volume regulation, in which NKCC transports sodium, potassium, and chloride ions across the cell membrane. It has been known that prostaglandin E2 (PGE2) induces an acute cell lysis of specific hemocyte type, oenocytoid, to release prophenoloxidase into the plasma and ouabain (a specific sodium pump inhibitor) inhibits the oenocytoid cell lysis resulting in preventing phenoloxidase activation. However, it is not clear how the intracellular signaling pathway leads to oenocytoid cell lysis in response to PGE2. This study was designed to analyze functional role of NKCC in the cell lysis to release prophenoloxidase. A gene structure of NKCC was derived from cDNA library of Spodoptera exigua hemocyte, NKCC was expressed in all developmental stages and tissues. A real time quantitative RT-PCR showed that bacterial challenge significantly induced its expression. Specific inhibitors of NKCC, bumetanide and chlorothiazide, clearly prevented the cell lysis in a dose dependent manner. When RNA interference using double stranded RNA (dsRNA) specific to NKCC suppressed its expression, the oenocytoid lysis and PO activation was significantly inhibited in response to PGE2. It also reduced nodule formation to bacterial challenge. These results indicate that NKCC is associated with oenocytoid cell lysis probably by increasing cell volume through inward transport of ions in response to PGE2.

Bacillus thuringiensis subsp. kurstaki KB100 isolated from the domestic soil have the most effective activity against the beet armyworm, Spodoptera exigua larva. The tannic acid as protease inhibitor might be increased the efficacy of sublethal concentrations of B. thuringiensis. The tannic acid was identified as a protease inhibitor that could increased the efficacy of sublethal concentrations of B. thuringiensis. Mixture of B. thuringiensis and tannic acid was investigated the mortality of S. exigua larva in the laboratory and field. When B. thuringiensis treated to 2nd larva of S. exigua, mortality was shown 54.4%. However, mixtures of B. thuringiensis with 4 and 40 mM tannic acid were increased mortalities to 2nd larva of S. exigua as 64.0 and 95.5%, respectively. Also, synergy effect of mixture of B. thuringiensis and 40 mM tannic acid was increased the mortality of S. exigua 3rd larva to 93.3%, even though 60.0% mortality with only B. thuringiensis treatment. On the other hand, the mortality of mixture with B. thuringiensis and 80 mM tannic acid was 53.3% lower than B. thuringiensis single treatment. In the welsh onion field, the accumulated mortalities of 3 times replicated with mixture of B. thuringiensis and 40 mM tannic acid were 83.9, 89.4 and 66.8% compare with 61.8, 80.4 and 47.3% as only B. thuringiensis treatment, respectively.

Bacillus thuringiensis subsp. aizawai CAB109 isolated in Korea is known active against Spodoptera sp.. Especially, B. thuringiensis aizawai CAB109 isolates showed 100% mortality against Spodoptera litura and Spodoptera exigua. To screen highly active B. thuringiensis, the pathogenicity of B. thuringiensis CAB109 was compared with that of commercialized B. thuringiensis products. LC₅₀ values of CAB109, product TB-WP and product SC strains of B. thuringiensis were 1.3x10⁵, 2.3x10⁶ and 5.2x10⁵ cfu/㎖ against the 2nd larva of S. litura and 1.8×10⁴, 1.3×10⁶ and 1.5×10⁶ cfu/㎖ against the 2nd larva S. exigua, respectively. To determine new gene"s existence and absence, the plasmid DNA was extracted, and compared to that of B.t. aizawai HD-133. Both B. thuringiensis were not like plasmid DNA pattern. PCR technique was used to predict both plasmid DNA"s cry gene. PCR products analysis showed that B.t. CAB109 harbor Cry1Aa, Cry1Ab, Cry1C and Cry1D and B.t. HD-133 has Cry1Aa and Cry1Ab, respectively.

14-3-3 proteins are known to play a pivotal role in a diverse array of cellular events such as cell survival, apoptosis, and signal transduction. Numerous 14-3-3 ζ have been cloned and characterized from a host of eukaryotic organisms including human, plants, yeast, fruit fly and silkworm. However, no study on Spodoptera exigua 14-3-3ζ in conjunction with virus infection has so far been reported in insects. It appears that expression of Se14-3-3ζ was decreased starting 24 h post-SeNPV infection as SeNPV titers seemed to increase as evidenced by intense bands of SeNPV IAP3. Interestingly, confocal microscopic analysis revealed that Se14-3-3ζ is expressed at the apical side of the NPV-uninfected gut cells, whereas it was detected mainly in the nucleus of the NPV-infected cells. Thus, despite the biological significance of Se14-3-3ζ in S. exigua in conjunction with molecular interactions between SeNPV and S. exigua is unclear now, our data suggest that Se14-3-3 ζ protein plays a role to protect S. exigua from the infection or inhibit replication of SeNPV.