Control of Tobacco Cutworm Moth Spodoptera litura Fabricius (Lepidoptera,Noctuidae) by Sex Pheromone Trapping Technology

[Objective] The paper was to promote using synthetic sex pheromone lures to control tobacco cutworm moth（Spodoptera litura Fabricius） .[Method] Three layers of pheromone traps for S.litura were set in the field at the density of 26 m×26 m（one trap/676 m2） to carry out field control test.[Result] The amount of egg massed reduced by 62.16% after trapping by sex pheromone under the density,and the larvae population was equivalent to those in the conventional control field with pesticides,the control effect was continuous,stable and significant.The larger the control area was,the better the effect was.[Conclusion] Using sex pheromone could effectively control S.litura and reduce pesticide usage for over 80% with economic,safe and efficient features,which should be incorporated into the technical control system of S.litura.

Biological activities of Solanum pseudocapsicum(Solanaceae)against cotton bollworm,Helicoverpa armigera Hübner and armyworm,Spodoptera litura Fabricius(Lepidotera:Noctuidae)

Objective:To evaluate the antifeedant,insecticidal and growth inhibition activities of Solanum pseudocapsicum(S.pseudocapsicum)seed extracts against Spodoptera litura(S.litura)and Helicotverpa armigera(H.armigera).Methods:Hcxane,diethyl cther,dichloromethanc and ethyl acetate seed extracts were prepared and tested for autifeedant,insecticidal and growth inhibitory activities against fourth instar larvae of&litura and H.armigera.Results:Ethyl acetate extract showed promising antifeedant and insecticidal activities against S.litura and H.armigera.Percentage of deformed larvae,pupae and adults were maximum in treatment of ethyl acetate extract.Percentage of successful adult emergence was deteriorated by seeds on extract treated larvae.Conclusions:Ethyl acetate extracts of S.pseudocapsicum,showed higher efficiency of antifeedant,insecticidal and growth inhibition activities.Hence,it can be used to controll agricultural insect pests,S.litura and H.armigera.

湖南烟区斜纹夜蛾(Spodoptera litura)的发生规律及预测方法

以郴州、宁远等县连续多年田间调查资料为基础,结合当地气象数据,分析了湖南省斜纹夜蛾的发生规律。结果表明,根据有效积温斜纹夜蛾在湖南每年发生4.0～4.5代,理论代数与实际代数相符;湖南斜纹夜蛾每年初始虫源全部为外地虫源;按虫源性质,全年可分为4个不同的发生时段;3月的诱蛾量与4—6月诱蛾量有显著的相关性,预测模型为y=233.54+112.44x4(r=0.815*,n=8);1月平均温度与4—6月诱蛾量也有明显的相关性(达90%可信度),预测模型为y1410350X3(r=0.595,n=9);同步迁飞昆虫小地老虎主迁入期(2—4月)的性诱蛾量与斜纹夜蛾主迁入期(4—6月)也具相关性,均可供发生趋势预测参考。斜纹夜蛾的百株虫量与为害率呈显著相关性。

斜纹夜蛾(Spodoptera litura)在我国的时空分布概述

概述了我国斜纹夜蛾的分布区以及在各分布区的始见虫时间。结果表明,斜纹夜蛾在我国目前的行政区划内除西藏未见报道外,其余各省、自治区、直辖市和特别行政区均有分布,主要分布于长江流域、华南和西南地区,西北地区则分布较少,在华北和东北地区分布介于二者之间;该虫可在1~2月的华南和西南地区越冬,甚至在部分地区终年可见,之后随着气温升高,向北迁飞,在长江流域、华东地区乃至华北和东北地区逐渐为害;在1~2月的华南和西南地区,该虫的寄主作物主要是槟榔芋、草莓、白莲、烟草、柑橘和蔬菜等。

高效简便合成斜纹夜蛾Spodoptera litura F.性信息素成分(Z,E)-9,11-十四碳二烯-1-醇乙酸酯

高效简便合成高纯度斜纹叶蛾性信息素,为该虫生物防治提供技术支持。以(E)-2-戊烯-4-炔-1-醇为出发原料,制成(Z,E)构型的烯基碲试剂,然后与有机铜试剂偶联得到构型保持的(Z,E)共轭二烯,成功合成斜纹夜蛾性信息素成分(Z,E)-9,11-十四碳二烯-1-醇乙酸酯(5),纯度(对映体过量值e. e.)达到99. 5%。

Application of Spodoptera litura Nucleopolyhedrovirus for Crop Pest Control

The laboratory bioassay and field control efficacy of Spodoptera litura nucleopolyhedrovirus（Spli NPV） Chenzhou strain were preliminarily examined. The efficient artificial propagation method was to feed the host larvae with virus suspension,and the average mortality of the insects was 65.0%. The death peak of the pests appeared 4-8 d after virus infection. The high temperature, high humidity and poor light could help the virus infection and propagation. Filed control efficacy of Chenzhou strain was 86.6% in laboratory, which was better than of another commercial strain. The corrected control efficacy of this strain was 88.4% the field, which was higher than that of avermectin pesticide significantly. It was detected that the occlusion body（OB） concentration of the initial virus＇ s stock solution was 1.03×1011OBs/ml,and it was a strong SpliNPV strain, as it showed an excellent efficacy to control the pest Spodoptera litura, and thus there will be a good prospect of application and development of this SpliNPV strain.

斜纹夜蛾(Spodoptera litura)的胚胎发育

本文利用实验胚胎学方法详细研究了斜纹夜蛾胚胎发育的全过程。结果表明：在２４±１℃的恒温条件下，仅需８７小时即可孵化出幼虫，同时证明了马氏管起源于外胚层。

Microsatellites reveal strong genetic structure in the common cutworm, Spodoptera litura

The common cutworm, Spodoptera litura(Lepidoptera: Noctuidae), is a voracious agricultural pest. To increase understanding of the migration patterns and genetic diversity of different geographic populations of this species, we analyzed genetic variation in nine microsatellite loci among 576 individuals collected from 17 locations in China and one in Myanmar during 2011–2012. We successfully identified 162 alleles, with an average of 18 alleles per locus and a range of 5 to 34. The mean observed heterozygosity of the 18 populations ranged from 0.18 to 0.98, and the expected heterozygosity ranged from 0.19 to 0.89. For the nine microsatellite markers studied, polymorphism information content ranged from 0.18 to 0.88(mean=0.64). We found low genetic differentiation among the 18 populations(mean F-statistics(F_(ST))=0.05) and high genetic diversity among individuals. Principle coordinates analysis indicated no significant correlation between geographic and genetic distance(r=0.04). The value of N_m(N_m>4) estimated using coalescent-based methods suggests strong gene flow with migration. The nine microsatellite markers identified in this study will be beneficial for further investigation of migration patterns and genetic diversity in S. litura.

Silencing JA hydroxylases in Nicotiana attenuata enhances jasmonic acid-isoleucine-mediated defenses against Spodoptera litura

Jasmonic acid(JA)plays important roles in plant resistance to insect herbivores.One important derivative of JA is 12-OH-JA,which is produced by two independent pathways:direct hydroxylation of JA by jasmonate-induced oxygenases(JOXs)or hydrolyzation of 12-OH-JA-Ile.Yet the function of 12-OH-JA in plant-herbivore interactions remains largely unknown.In this study,we silenced four JOX homologs independently in the wild tobacco Nicotiana attenuata by virus-induced gene silencing(VIGS),and found that all four JOX homologs are involved in JA hydroxylation.Simultaneously silencing the four JA hydroxylases in VIGS-NaJOXs plants decreased herbivory-induced 12-OH-JA by 33%,but JA and JA-Ile levels increased by 45%and 30%,respectively,compared to those in control plants.Compared to direct hydroxylation from JA,hydrolyzation from 12-OH-JA-Ile is equally important for herbivory-induced 12-OHJA accumulation:in the 12-OH-JA-Ile deficient irJAR4/6 plants,12-OH-JA decreased 34%.Moreover,VIGSNaJOXs plants exhibited enhanced resistance to the generalist herbivore Spodoptera litura.The poor larval performance was strongly correlated with high levels of several JA-Ile-dependent direct defense metabolites in the VIGS-NaJOXs plants.When we simultaneously silenced all four JA hydroxylases in the JAIle-deficient irJAR4/6 background,the enhanced herbivore resistance diminished,demonstrating that enhanced herbivore resistance resulted from elevated JA-Ile levels.Given that silencing these NaJOX-like genes did not detectably alter plant growth but highly increased plant defense levels,we propose that JOX genes are potential targets for genetic improvement of herbivore-resistant crops.

Oxidative Damage to Spodoptera litura Cell Induced by α-Terthienyl

In this study, the oxidative damage of α-terthienyl （α-T） to the Spodoptera litura （SL） cell and its mechanism were investigated. MTT was used to compare the toxicity of α-T and rotenone to the SL cell. The output of malondialdehyde and relative content of glutathione were determined with 2-thiobarbituric acid （TBA） and 5, 5＇-dithio-bis （2-nitrobenzoic acid） （DTNB）, respectively. Transmission electron microscope （TEM） was employed to observe the influence of α-T on the membrane and organelle of the SL cell. The result showed that the IC50 value of α-T to the SL cell was 0.21 μg mL^-1, whereas the corresponding dose of rotenone was 12.25 μg mL^-1. The output of MDA had the same changing tendency with the concentration of α-T, whereas the content of GSH had the negative correlation with it. According to TEM, the cell membrane and karyotheca swelled and couldn＇t retain integrity, the intracellular substances leaked out, unidentified granules appeared in the SL cell. The mitochondria expanded, and the membrane and subcellular organelle were damaged severely. In this study, it was found that after oxidative damage induced by α-T, the output of MDA increased notably, whereas the relative content of GSH decreased. This indicated that the antioxidant ability of cell weakened. The result of TEM implied that the SL cell suffered from oxidative damage under the appointed dose.

Occurrence Regularity and Sexual Pheromone Trapping Effect of Spodoptera litura in Field in Central Guizhou

The Spodoptera litura occurrence quantity in Tianlong Town,Pingba County,Anshun City was dynamically monitored by an insect sex pheromone electronic measurement and forecast system in 2015 and 2016 and the trapped effect of S. litura was studied by the home-made S. litura sex pheromone traps in Baishiyan Town,Ziyun County and Tianlong Town,Pingba County in 2016 to accurately grasp the occurrence regularity of S. litura and apply insect sex pheromone for controlling S. litura in Central Guizhou tobacco-growing region. There are 5 generations of S. litura in a year in Central Guizhou region. The first generation of S.litura occurs from late April to middle May,the second from middle-to-late July to middle-to-late August,the third from early-to-middle August to the end of September,the fourth is in the end of October and the fifth in the end of November. S. litura emigrates or enters into the overwintering stage in December. S. litura is almost in active in the daytime during the peak occurrence period of S. litura adults. The first mating time of S. litura is at 17: 30 and its peak mating time is about 22: 00. The second mating time of S. litura is at 1: 00-5: 00 and its peak mating time is about 2: 30. The trapped S. litura quantity presents an obvious layer-belt distribution that the number in the outer ring is significantly higher than that in the middle ring,and the number in the middle ring is significantly higher than that in the inner ring. The number of trapped S. litura is higher around the outer ring of the testing field and at the draught position than in the low-lying land and inner flat ground.

Transcriptome and metabolome analysis reveal that oral secretions from Helicoverpa armigera and Spodoptera litura influence wound-induced host response in cotton

Cotton(Gossypium hirsutum)is an important fiber crop worldwide.Insect attack causes cotton yield and quality losses.However,little is known about the mechanism of cotton response to insect attack.We simulated insect feeding by applying insect oral secretions(OS)to wounds,and combined transcriptome and metabolome analysis to investigate how OS from two major pest species(Helicoverpa armigera and Spodoptera litura)affect cotton defense responses.We found that respectively 12,668 and 13,379 genes were differentially expressed in comparison with wounding alone.On addition of OS,the jasmonic acid signaling pathway was rapidly and strongly induced,whereas genes involved in salicylic acid biosynthesis were downregulated.On constructing a coexpression gene network,we identified a hub gene encoding a leucine-rich repeat receptor kinase that may play an important role in early signal recognition and transduction.OS from the two insect species altered the abundance of flavonoid-related compounds in different patterns.Gossypol remained in lower concentration after OS application than after wounding alone,suggesting a suppressive effect of OS on cotton defense response.This study illustrated transcriptional and metabolic changes of cotton in responding to OS from two chewing insect species,identified potential key response genes,and revealed evidence for OS inhibition of wounding-induced cotton defense response.

Transient expression of SbDhr2 and MeHNL in Gossypium hirsutum for herbivore deterrence assay with Spodoptera litura

Background:Spodoptera litura(Lepidoptera:Noctuidae),commonly known as tobacco cutworm or cotton leafworm,is a polyphagous pest which causes considerable damage to cotton(Gossypium hirsutum)and other crops.Herbivore-induced defence response is activated in plants against chewing pests,in which plant secondary metabolites play an important role.Dhurrinase2(SbDhr2),a cyanogenicβ-glucosidase from Sorghum bicolor,is the key enzyme responsible for the hydrolysis of dhurrin(cyanogenicβ-glucosidic substrate)to phydroxymandelonitrile.Hydroxynitrile lyase(Me HNL)from Mannihot esculanta catalyses the dissociation of cyanohydrins to hydrogen cyanide and corresponding carbonyl compound,both enzymes play a pivotal role in plant defence mechanism.Results:SbDhr2 and Me HNL genes were expressed individually and co-expressed transiently in cotton leaves.We examined the feeding response of S.litura to leaves in the choice assay.The S.litura population used in this study showed better feeding deterrence to leaves co-expressing both genes compared with the expression of an individual gene.Conclusion:Our results suggest that co-expression of SbDhr2 and Me HNL genes in cotton leaves demonstrate feeding deterrence to S.litura.Engineering cyanogenic pathway in aerial parts of cotton would be an additional defence strategy against generalist pests and can be enhanced against specialist pests.

Ovicidal activity of Atalantia monophylla(L)Correa against Spodoptera litura Fab.(Lepidoptera:Noctuidae)

Objective:To evaluate the efficacy of Atalantia monophylla(A.monophylla)leaf in different solvent crude extracts and fractions against eggs of Spodoptera litura(S.litura).Methods:Hexane,ethyl acetate and chloroform solvent extracts of A.monophylla leaf and 12 fractions from hexane extract were screened at 5.0%t,2.5%,1.0%and 0.5%for crude extracts and 1000,500,250 and 125 mg/kg for fractions against the eggs of S.litura for the ovicidal activity.LC_(50)and LC_(90)were calculated using probit analysis.Results:Hexane crude extract showed maximum ovicidal activity of 61.94%at 5.0%concentration with a correlation value of r^2=0.81,and least LC_(50)value of3.06%.Hexane extract was fractionated using silica gel column chromatography and 12 fractions were obtained.Fraction 9 was active which showed maximum ovicidal activity of 75.61%at 1000mg/kg with the LC_(50)value of 318.65 mg/kg and LC_(90)value of 1473.31 mg/kg.In linear regression analysis,significant and high correlation(r^2=0.81%)was seen between concentration and ovicidal activity of hexane crude extracts and its active frsctien.Conclusions:As per our knowledge,this is the first report for ovicidal activity of A.monophylla against S.litura,A.monophylla could be used for the management of S.litura and other insect pests.

Effect of Trap Space Layout on Trapped Number of Spodoptera litura in Tobacco Field

[Objectives] This study was to find out the effect of trap space layout on the trapped number of Spodoptera litura in tobacco field. [Methods]From2015 to 2017,investigations were made using different hanging heights,distances( densities) and equidistant plane layout in the tobacco planting area in central Guizhou Province. [Results] The trapped number of S. litura was different at different hanging heights of the trap,and some had the difference reached the5% significant level in the trapped number. The optimum hanging height was 1. 5-2. 0 m. The trapping effect was the best at the field layout distance of20. 0-30. 0 m( density of 5-8 traps/hm^2). Under the conditions of even distribution at the equal distance between traps of 40.0 m in the field,the accumulated trapped number of S. litura from April to August was in the order of outer ring > central ring > inner ring,presenting the zonal distribution. The difference in the trapped numbers was significant among different rings,reaching the 5% significant level. [Conclusions]This study provided theoretical bases for the physiochemical control of S. litura in tobacco field.

Control Effects of Different Densities of Chemical Pheromones against Tobacco Cutworm Moth ( Spodoptera litura)

[ Objective ] The paper was to study the most suitable density of chemical pheromone to control Spodoptera litura in tobacco fields. [ Method ] Sixteen traps （ 4 lines x 4 rows） were placed according to the specifications of 25. 8 m ×25.8 m （ 15. 0 trap/hm2 ）, 31. 6 m× 31.6 m （ 10.0 trap/hm2 ） and 36.5 m × 36.5m （ 7.5 trap/hm2 ）. Meanwhile, a control area larger than 2 hm2 was set up with three repetitions. [ Result] Without consideration of impact of wind direc- tion, the amount of trapping moth increased with the increasing controlled area of single trap, but difference of trapping amount of moth was not significant under three different density treatments. Three placement densities could effectively control S. liture in tobacco fields, thereby reduce the use of pesticides and protect the natural enemies and reduce the control cost. [Conclusion] The suitable density of chemical pheromone traps to control S. litura was 31. 6 m x31. 6 m （10.0 trap/hm2 ）.

Expression,regulation and binding affinity of fatty acid-binding protein 2 in Spodoptera litura

Fatty acid-bindi ng proteins(FABPs)are a family of lipid chaper on es,which con tribute to systemic metabolic regulati on through diverse lipid signalings.In this study,a midgut-specific FABP gene(Slfabp2)was cloned from Spodoptera litura.RT-PCR and Western blot analysis indicated that RNA and protein levels of S/FABP2 gradually increased and reached a peak at the prepupal stage and maintained a high level during the pupal stage.The expression of S/FABP2 protein was induced by starvation treatment.In vitro binding assay revealed that the recombinant S/FABP2 had high mffinities of binding Iong-chain fatty acids,such as palmitic acid,arachidonate and oleic acid.The results suggest that S/FABP2 may have a unique function that transports intracellular fatty acids and can regulate the metabolism of lipids in metamorphosis.This work provides experimental clues for understanding the potential function of S/FABP2 in fatty acid metabolism in S.litura.

Prediction of Occurrence Trend of Spodoptera litura in Hunan Province in 2010——with Chenzhou Area as an Example

[Objective] The paper was to predict the occurrence trend of Spodoptera litura in Chenzhou area in 2010. [Method] With filed survey data for continuous years in Chenzhou and Ningyuan areas in Hunan Province as basic data, combining with local meteorological data, the occurrence law of S. litura in Chenzhou area in 2010 was predicted in the paper. [Result] With Chenzhou as an example, the occurrence quantity of S. litura during April and June in 2010 was only second to 2002 and 2003, which was higher than other years, indicating that 2010 would be the year with moderate and slightly heavier occurrence of S. litura. The occurrence quantity of S. litura during April and June was predicted by using temperature in January, and the correlation coefficient was significant, reaching the reliability degree of 90%. The occurrence quantity of S. litura during April and June was predicted by using sexually trapped moth during February and March, the correlation between them was very high, reaching the reliability degree of 98%. The sexually trapped moth of S. litura during April and June was predicted using sexually trapped moth by black cutworm （Agrotis ypsilon） during February and April, and the correlation coefficient between them reached the reliability degree of 90%. [Conclusion] The study provided reference for integrated control of S. litura.

Occurrence and Damage Regularity of Spodoptera litura in Broccoli

[Objective] The paper was to explore the occurrence and damage regularity of Spodoptera litura in broccoli,and to reveal the annual movement regularity and seasonal fluctuation regularity of S.litura population.[Method] The monitoring data of sexual attractants at fixed points for 11 consecutive years were summarized and analyzed.[Result] The large occurrence frequency of S.litura in Taizhou was 36.4%;the annual movement showed a downward-opening parabolic form,and the movement trajectory was N =-18.416 t^(2)+182.51 t +179.71,t ={1,2,3,…,n}(n =11;r =0.691 7*).The seasonal fluctuation showed a trend of peak oscillation attenuation curve,and the total moth quantity gradually decreased from sowing to heading stage.The functional model of average daily quantity was m=0.000 2 d^(2)-0.067 5 d+6.797 3,d={1,2,3,…,n}(n =186,r=0.955 2**).Air temperature was the main external factor affecting the seasonal variation of quantity,and there was a significant correlation be-tween the number of ten-day moth trapping quantity and ten-day average temperature:M =0.243 T^(2)-6.935 1 T +46.681(n =108,r =0.560 2**)or M=2.734 4 T-35.446(n=108,r=0.500 3**).Therefore,the moth quantity in the field increased with the increase of ten-day average temperature,and the period from July to September with high temperature and less rainfall was the peak occurrence period of S.litura.[Conclusion] These models can be used to improve the prediction and early warning levels of S.litura in broccoli,and has good guiding significance for decision-making and prevention.

Effects of Sublethal Doses of Chlorfluazuron on Ovarioles in the Common Cutworm, Spodoptera Litura （F.） （Lepidoptera： Noctuidae）

Chlorfluazuron is an insect growth regulator for controlling the major insect pests in crops. This paper describes the effects of sublethal doses （LD10：1.00 ng/larva; LD30：3.75 ng/larva） of chlorfluazuron on ovarioles during ovarian development and oogenesis of common cutworm, Spodoptera litura （F.）. It is a significant pest of cotton, tobacco and miscellaneous vegetables. The LDlo or LD3o was applied topically to the newly-ecdysed fifth-instars of S. litura under laboratory conditions. In controls, on 2nd day of adult emergence, the cell density in germarium was 1636 ± 9.17 nuclei/mm^2. It increased until 3rd day, i.e., 1829 ± 8.87 nuclei/mm^2 and decreased thereafter. In the LDloor LD-3o-treated insects, the patterns of the cell density was the same as in controls but values were significantly （P 〈 0.05） decreased in the LD10- and more in the LDa0-treated females compared with controls. In control, ovaries were normal type and had mature ova with an occasional one or two being absorbed. In LD10-treated females, ovaries had spaces in ovarioles and absorption of ova. In LD30-treated females, besides the spacing and absorption, sometimes only immature （germarium） ova were found.