草地贪夜蛾Spodoptera frugiperda(Smith)成虫

正草地贪夜蛾隶属于鳞翅目(Lepidoptera)夜蛾科(Noctuidae)原产地为美洲热带和亚热带气地区。2016年入侵非洲,2018在亚洲的印度首先发现并快速扩散到周边国家,2019年1月入侵中国云南并迅速扩散到20多个省区。草地贪夜蛾成虫翅展32-40 mm,前翅深棕色,后翅白色,边缘有褐色带。雌蛾前翅呈灰褐色或     

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。     

Seasonal abundance of two armyworm species, Spodoptera exitgua (Hübner) and Spodoptera litura (F.) in the Philippines

The two armyworm species Spodoptera exigua (Hübner) and S. litura (F.) are Important pests on several agricultural crops in the tropics. Knowledge about species abundance is important for the development of integrated pest management strategies. During 1998 and 1999 population densities were recorded weekly using pheromone traps at San Leonardo and Munoz (Province Nueva Ecija, 150 km north of Metro Manila) on the Philippine island Luzon. Furthermore, meteorological conditions and natural enemies were observed. Both armyworm species were present year-round at both observation sites. No differences in numbers of male insects trapped in pheromone traps between seasons were found for S. litura. Contrary, numbers of male S. exigua trapped during rainy season was significant higher than during dry season. Rainfall explained between 30 and 40% of trapped moths and has to be considered when monitoring population density with pheromone traps. Parasitism rates were below 5% in both years and for both species and can not explain the high variation observed in population densities.     

草地贪夜蛾Spodoptera frugiperda(Smith)成虫

正草地贪夜蛾隶属于鳞翅目(Lepidoptera)夜蛾科(Noctuidae)原产地为美洲热带和亚热带气地区。2016年入侵非洲,2018在亚洲的印度首先发现并在南亚和东南亚快速扩散到周边国家,2019年1月入侵中国云南并迅速扩散到20多个省区。草地贪夜蛾成虫傍晚至夜间活动,温暖潮湿的夜晚最活跃。成虫寿命7-21 d。雌蛾准备交配时,     

草地贪夜蛾Spodoptera frugiperda(Smith)成虫

正草地贪夜蛾隶属于鳞翅目(Lepidoptera)夜蛾科(Noctuidae)原产地为美洲热带和亚热带气地区。2016年入侵非洲,2018在亚洲的印度首先发现并在南亚和东南亚快速扩散到周边国家,2019年1月入侵中国云南并迅速扩散到20多个省区。草地贪夜蛾发育速度会随着气温的提升而变快,一年可繁殖1-6代。雌性成虫通常在羽化当天不会产卵,而在随后的4-5 d产下大部分卵,产卵最多可持续2周以上。一只雌蛾一生可产卵超过1 000粒。     

草地贪夜蛾Spodoptera frugiperda(Smith)成虫

正草地贪夜蛾隶属于鳞翅目(Lepidoptera)夜蛾科(Noctuidae)原产地为美洲热带和亚热带气地区。2016年入侵非洲,2018在亚洲的印度首先发现并在南亚和东南亚快速扩散到周边国家,2019年1月入侵中国云南并迅速扩散到20多个省区。草地贪夜蛾成虫在美洲有规律地一年从北向南迁飞1次,产卵前期广泛扩散。成虫可进行长距离的飞行,成虫一晚可飞行超过100 km,一个世代成虫可借助气流迁飞500 km。草地贪夜蛾成虫可以取食多种植物的花蜜。     

增殖细胞核抗原蛋白在Spodoptera frugiperda昆虫细胞中的表达及纯化

目的:利用昆虫细胞表达系统生产重组的人增殖细胞核抗原(proliferating cell nuclear antigen,PCNA),并进行纯化和抗体结合特性鉴定。方法:以HeLa细胞逆转录的cDNA为模板,扩增人PCNA基因,并插入杆状病毒载体AcMNPV。利用昆虫细胞得到PCNA基因的重组杆状病毒。病毒感染细胞表达蛋白,联合镍柱亲和层析和离子交换层析获得高纯度的重组人PCNA蛋白。ELISA法测定抗体结合特异性。结果:以HeLa细胞cDNA为模板得到的基因序列同GenBank的人PCNA基因序列一致。草地贪夜蛾细胞(Spodoptera frugiperda,Sf9)表达重组人PCNA(recombinant human PCNA,rPCNA)的最佳感染值(MOI)和感染时间分别为0.05h和144h。rPCNA的产量高达110mg/L细胞,纯度95%。间接ELISA法检测抗体结合特性,rPCNA的敏感性和特异性分别为93.3%和85.0%。结论:建立了rPCNA的表达和纯化方法,获得了高效表达、高度抗体结合特异性的PCNA蛋白,该蛋白质能进一步开发为PCNA相关疾病的体外诊断试剂盒,具较大的应用价值。     

A comparison of the pre-calling period between Japanese and southeastern Asian populations of Spodoptera litura

The pre-calling behavior of female adults of the common cutworm, Spodoptera litura （Lepidoptera： Noctuidae） collected in southern Japan and southeastern Asian countries was investigated. Most females started calling on days 1-4 after adult emergence. In three populations obtained in Saga prefecture in Kyushu mainland, Japan, two different patterns of pre-calling period （PCP） were observed： one was the above-mentioned pattern shown by most individuals, and the other was a pattern in which females sexually matured within several hours after emergence. Diel periodicity was shown in the time of calling activity, and its pattern varied among the populations. Pre-calling period was stable over successive generations in the laboratory.     

Molecular cloning and characterization of the α-glucosidase II from Bombyx mori and Spodoptera frugiperda

The α-glucosidase II (GII) is a heterodimer of α- and β-subunits and important for N-glycosylation processing and quality control of nascent glycoproteins. Although high concentration of α-glucosidase inhibitors from mulberry leaves accumulate in silkworms (Bombyx mori) by feeding, silkworm does not show any toxic symptom against these inhibitors and N-glycosylation of recombinant proteins is not affected. We, therefore, hypothesized that silkworm GII is not sensitive to the α-glucosidase inhibitors from mulberry leaves. However, the genes for B. mori GII subunits have not yet been identified, and the protein has not been characterized. Therefore, we isolated the B. mori GII α- and β-subunit genes and the GII α-subunit gene of Spodoptera frugiperda, which does not feed on mulberry leaves. We used a baculovirus expression system to produce the recombinant GII subunits and identified their enzyme characteristics. The recombinant GII α-subunits of B. mori and S. frugiperda hydrolyzed p-nitrophenyl α-d-glucopyranoside (pNP-αGlc) but were inactive toward N-glycan. Although the B. mori GII β-subunit was not required for the hydrolysis of pNP-αGlc, a B. mori GII complex of the α- and β-subunits was required for N-glycan cleavage. As hypothesized, the B. mori GII α-subunit protein was less sensitive to α-glucosidase inhibitors than was the S. frugiperda GII α-subunit protein. Our observations suggest that the low sensitivity of GII contributes to the ability of B. mori to evade the toxic effect of α-glucosidase inhibitors from mulberry leaves.     

Host plant selection and development in Spodoptera exigua: do mother and offspring know best?

We examined the ovipositional preference and larval development of Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) on two common hosts in southern California, Chenopodium murale L. (Chenopodiaceae) and Apium graveolens L. (Umbelliferae) to determine if female oviposition preference is correlated with offspring performance. Greenhouse oviposition choice tests indicated that S. exigua oviposit more frequently on C. murale than on A. graveolens. However under laboratory conditions, larvae reared on C. murale had longer development times, lower relative growth rate, and lower survivorship than larvae reared on A. graveolens. larval and pupal masses were significantly greater on A. graveolens than on C. murale. Furthermore, pupal masses were significantly greater for individuals reared on A. graveolens than on C. murale. Because pupal masses and adult fecundity are positively correlated for Spodoptera spp., the fitness of S. exigua on A. graveolens is likely to be substantially higher than its fitness on C. murale. Despite better larval performance on A. graveolens, previous results from choice tests with whole plants and leaf discs indicate that the highly mobile S. exigua larvae strongly prefer C. murale over A. graveolens. Hypotheses attempting to explain this lack of correlation between larval and adult host preference versus development and survival in this system are discussed.     

Toxicity of Insecticides and Metabolism of Deltamethrin in Helicoverpa assulta Guenéee and Spodoptera litura Fabricius

This experiment was carried out to evaluate the effects of synergists on toxicity of deltamethrin and to investigate the pharmacokinetics of deltamethrin in Helicoverpa assulta Guenéee and Spodoptera litura Fabricius. Susceptibilities of H. assulta and Haman-collected S. litura to 7 insecticides revealed different responses between the 2 species. The different susceptibility of the 2 species to deltamethrin was correlated with the differences in the penetration and metabolism. Larvae of H. assulta pretreated with synergists (piperonyl butoxide (PB), S-benzyl-O, O-diisopropyl phosphorothioate (IBP), and diethyl maleate (DM) were more sensitive to deltamethrin, with the highest synergism ratio (SR = 6.8) being observed with PB. Significant differences in synergism among synergists were not observed. For S. litura, the highest SR(=8.8) was observed with PB. At all time periods, the penetration of ¹⁴C-deltamethrin was relatively faster to S. litura than to H. assulta. Time (hrs) required for 20% (t₂₀) of the applied doses to be excreted from treated S. litura was 1.5-fold faster than that of H. assulta. Higher synergism and longer retention in larval body of S. litura by the addition of PB suggest that the mixed function oxidase be a major factor in detoxification of deltamethrin. The combined use of PB with deltamethrin, and possibly other pyrethroids, might indicate a potential for controlling field populations resistant to deltamethrin and other pyrethroids.     

Inhibition of a Δ-11 desaturase in Spodoptera littoralis by 12,13-methylenehexadec-12-enoic acid

Mass-labelling experiments with selectively deuterated palmitic acids demonstrate that Δ-11 desaturation of this acid is part of the biosynthetic pathway of the female sex pheromone blend of Spodoptera littoralis. The desaturation step is efficiently inhibited by 12,13-methylenehexadec-12-enoic acid, a cyclopropene fatty acid, which is thus able to interfere with the sex pheromone production.     

Purification of ecdysone oxidase and 3-dehydroecdysone 3α-reductase from the cotton leafworm,Spodoptera littoralis

The 3-epimerization of ecdysteroids (insect moulting hormones) is an inactivation pathway of the hormones that has been reported to occur in midgut cytosol of Lepidoptera. The pathway involves ecdysone oxidase-catalysed conversion of ecdysone into 3-dehydroecdysone, which is then irreversibly reduced to 3-epiecdysone by 3DE 3α-reductase. In this study, ecdysone oxidase and 3DE 3α-reductase from the cotton leafworm, S. littoralis, have been purified by extensive chromatography together with electrophoresis on native gels. Gel filtration suggested that the native ecdysone oxidase might be a trimer with apparent molecular mass of approximately 190 kDa, since the apparent molecular mass of the oxidase subunit was determined to be 64 kDa by SDS-PAGE. Two forms of 3DE 3α-reductase were observed during the purification, the 26 kDa form reductase has been purified to homogeneity and the second form of the reductase identified as a 51 kDa protein. The former reductase may be a trimer with apparent molecular mass of 76 kDa, whilst the latter was suggested to be a monomer by gel filtration. Chromatographic behaviour suggested that the 26 kDa form of the reductase has a lower pI value and a higher degree of hydrophobicity than that of the 51 kDa reductase. Substrate specificity and the tissue distribution of these enzymes are discussed.     

交配和温度对甜菜夜蛾(Spodoptera exigua)雌蛾性信息素产生的影响

研究表明,交配对甜菜夜蛾雌蛾性信息素各组分的滴度,比例及其在个体间的变异均无显著的影响,因此交配不影响雌蛾在下一暗期的再次求和交配,环境温度对甜菜夜蛾性信息素的产生则有显著的影响,15－25℃最有利于甜菜夜蛾性信息素的产生,而10℃低温和35℃主温则使信息素产生受到明显影响,其中以10℃低温的影响更甚。10℃低温不仅使各组分的滴度产生显著改变,而且使二元性信息素组分的比例受到显著影响,并使二元组分通讯信息的个体间变异明显增大（CV＞10％）,这些改变必半扰乱甜菜夜蛾雌雄间的正常交配。     

Transcytosis of Junonia coenia densovirus VP4 across the gut epithelium of Spodoptera frugiperda(Lepidoptera:Noctuidae)

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.     

Crystallization of α- and β-carotene in the foregut of Spodoptera larvae feeding on a toxic food plant

In the animal kingdom, carotenoids are usually absorbed from dietary sources and transported to target tissues. Despite their general importance, the uptake mechanism is still poorly understood. Here we report the “red crop” phenomenon, an accumulation of ??- and ??-carotene in crystalline inclusions in the enlarged foregut of the polyphagous Spodoptera larvae feeding on some potentially toxic plant leaves. The carotene crystals give the insect foregut a distinctive orange-red color. The crystals are embedded in a homogenous lawn of the bacterium Enterococcus casseliflavus, but the carotene seems to be selectively taken from the food plant. Caterpillars which fail to develop these carotene crystals exhibit a high mortality or fail to develop to adulthood. The crystallization of carotene and the enlargement of the foregut thus appears to manifest a multiple-step physiological adaptation of the insects to toxic food plants.     

Population structure of Spodoptera frugiperda maize and rice host forms in South America: are they host strains?

Determining which factors contribute to the formation and maintenance of genetic divergence to evaluate their relative importance as a cause of biological differentiation is among the major challenges in evolutionary biology. In Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) two host strains have been recognized in the 1980s: the corn‐strain prefers maize, sorghum, and cotton, whereas the rice‐strain prefers rice and wild grasses. However, it is not clear to what extent these so‐called ‘strains’, which have also been called ‘host races’ or even ‘sibling species’, are really associated with host plants. Due to the indeterminate evolutionary status, we will use the term ‘host forms’ (sensu Funk). Here, we characterized populations collected from maize, rice, and wild grasses from three countries in South America. Using two mitochondrial cytochrome oxidase I (mtCOI) markers and 10 polymorphisms in the triose phosphate isomerase (Tpi) gene, we found various patterns of host association. Two hundred twenty‐seven nuclear amplified fragment length polymorphisms (AFLPs) markers revealed significant genetic differentiation among populations, which was generally correlated to the host from which the larvae were collected. Using a multivariate discriminant analysis and a Bayesian clustering approach, we found that individuals could be grouped into 2–5 genetically distinct clusters, depending on the method. Together, our results indicate that although host‐associated differentiation is present in this species, it does not account for all observable genetic variation and other factors must be maintaining genetic differentiation between these forms. Therefore, the term ‘host strains’ should be abandoned and ‘host forms’ should be used instead for S. frugiperda.     

RNA interference of β1 integrin subunit impairs development and immune responses of the beet armyworm, Spodoptera exigua

Integrin is a cell surface protein that is composed of α and β heterodimer and mediates cell interaction with extracellular matrix or other cells including microbial pathogens. A full length cDNA sequence (2862 bp) of a β1 subunit integrin (βSe1) was cloned from the beet armyworm, Spodoptera exigua. Phylogenetic analysis showed that βSe1 was clustered with other insect β integrin subunits with the highest amino acid sequence identity (98.3%) to β1 of Spodoptera litura. Structural analysis of the deduced amino acid sequence indicated that βSe1 possessed all functional domains known in other insect β1 integrins. RT-PCR analysis showed that βSe1 was expressed in all developmental stages and all tested tissues of S. exigua. Its expression was further upregulated in hemocytes by injections of various microbes from quantitative RT-PCR analysis. Injection of double-stranded βSe1 RNA (dsRNA^βSe1) into late instar S. exigua suppressed βSe1 expression and resulted in significant reduction in pupal weight. The dsRNA^βSe1 injection significantly impaired hemocyte-spreading and nodule formation of S. exigua in response to bacterial challenge. Furthermore, oral ingestion of dsRNA^βSe1 induced reduction of βSe1 expression in midgut and resulted in significant mortality of S. exigua during immature development. These results suggest that βSe1 plays crucial roles in performing cellular immune responses as well as larval development in S. exigua.     

Interactions between a commercial preparation of Bacillus thuringiensis and β-exotoxin in the fall armyworm,Spodoptera frugiperda

A commercial preparation of Bacillus thuringiensis (Dipel) and its β-exotoxin were assayed alone and in combination against neonate (3- to 6-hr-old) fall armyworm, Spodoptera frugiperda, larvae using a microdroplet technique. Positive dosage-mortality response curves were determined for each agent. Combination bioassays were then conducted using dosages based on these curves. Presence or absence of interactions was determined by comparing mortality levels from the combination assays with expected mortality levels using single degree of freedom χ² tests. Synergism occurred in 14 of 18 combinations of B. thuringiensis and β-exotoxin tested. Four combinations, all of which contained low individual dosages, exhibited additivity of effects. Maximum deviation of observed from expected mortality occurred at the combination of LC₃₀ for B. thuringiensis plus LC₃₀ for β-exotoxin (observed = 100%, expected = 51%). The data suggested that both agents were contributing to the synergism in this system, but that B. thuringiensis was a slightly stronger synergist than β-exotoxin.