寄主植物对甜菜夜蛾的发育和繁殖及体内酯酶活性的影响

在恒温(2 8±1 )℃条件下考察了葱、苋菜、豇豆、蕹菜、菜心5种寄主植物对甜菜夜蛾SpodopteraexiguaH櫣ｂｎｅｒ的营养效应及体内羧酸酯酶、乙?铛ッ富钚缘挠跋?,结果表明,不同寄主植物对甜菜夜蛾幼虫和蛹的发育历期、存活率、蛹重、雌成虫产卵量等有显著影响,其中对雌成虫产卵量的影响最大。雌成虫产卵量最高为取食菜心的处理,其次是取食葱的处理。寄主植物对甜菜夜蛾体内羧酸酯酶、乙酰胆碱酯酶活性也有显著影响,但这些酶的活性与发育历期、存活率、产卵量无明显相关性。在进行预测预报、田间防治时应充分考虑寄主植物对甜菜夜蛾发育历期、产卵量、解毒酶活性的影响。     

甜菜夜蛾群体繁殖及其对杀虫剂毒力敏感性测定

用黄豆粉、麦胚粉、酵母粉为主要营养成份研制成人工饲料,实现了甜菜夜蛾大量饲养及群体繁殖,与自然饲料相比,人工饲料饲养甜菜夜蛾幼虫存活与成虫产卵量明显增加,室内用浸渍法测定11种杀虫剂对甜菜夜蛾2龄幼虫的毒力,结果表明,田间甜菜夜蛾种群对除尽,米满,菜喜最敏感,其次是对抑太保,卡死克,毒丝本,高效灭百可,快灵,对锐劲特,氯氰菊酯,乙酰甲胺磷的毒力均已高度不敏感。     

甜菜夜蛾对虫酰肼的抗性选育、风险评估及交互抗性

虫酰肼是目前防治甜菜夜蛾Spodoptera exigua（Hübner）的一种主要杀虫剂,为评估其抗性风险,在室内进行了抗性筛选和交互抗性的研究。采用饲料感染法,在甜菜夜蛾饲养75代期间用虫酰肼筛选62代,与起始种群相比抗性上升39.2倍,与室内敏感品系相比抗性上升141.3倍。在筛选的早、中、后期,现实遗传力h²分别为0.1075（F₀～F₂₅）、0.2780（F₂₆～F₅₀）和0.0538（F₅₁～F₇₅）,整个筛选62代现实遗传力为0.1556。抗性种群筛选43次（F55）后停止用药筛选,饲养21代后,与敏感品系相比,抗性水平由63.5倍下降到21倍,抗性下降3倍。说明甜菜夜蛾具有对虫酰肼产生抗性的风险,且抗性衰退缓慢,短期内很难恢复到敏感水平。交互抗性测定结果表明,上述室内选育的抗性品系对甲氧虫酰肼具有71.4倍的高水平交互抗性,对阿维菌素具有13.1倍的中等水平交互抗性,对甲维盐、茚虫威和呋喃虫酰肼分别具有7.0、8.4和4.7倍的低水平交互抗性,但对溴虫腈交互抗性不明显（1.9倍）。结果提示： 间断交替使用虫酰肼可以延缓抗性的发展,但除溴虫腈外,虫酰肼和其他几种新型杀虫剂之间的轮用可能不是甜菜夜蛾抗性治理的有效策略。     

甜菜夜蛾抗药性研究现状

就有关甜菜夜蛾Spodoptera exigua(Hbner)对常用杀虫剂的抗药性现状作综述。甜菜夜蛾对拟除虫菊酯类、有机磷类、氨基甲酸酯类杀虫剂已产生了较高水平的抗药性,其中山东泰安抗性种群对氯氟氰菊酯的抗性高达2445.5倍;对多杀菌素等生物杀虫剂产生了中低水平的抗性;对昆虫生长调节剂如虫酰肼的敏感性也有所降低,但昆虫生长调节剂依然是比较理想的防治药剂。对交互抗性及抗性治理也作了阐述。     

Effect of tinopal LPW on the insecticidal properties and genetic stability of the nucleopolyhedrovirus of Spodoptera exigua (Lepidoptera: Noctuidae)

The influence of an optical brightener, Tinopal LPW, on the activity of a purified genotype of the nucleopolyhedrovirus (SeMNPV) of the beet armyworm, Spodoptera exigua (Hübner), was determined in second to fifth instar (L2-L5) S. exigua. When mixed with viral occlusion bodies (OB) 1% Tinopal LPW significantly reduced the median lethal dose (LD50) of the virus in all instars compared with insects treated with SeMNPV alone. Levels of enhancement, as determined by LD50 values, ranged from 2.6- to 580-fold, depending on the instar. The greatest enhancement occurred on the two later instars, L4 (70-fold) and L5 (580-fold), which show a much higher resistance to SeMNPV infection than earlier instars. The median time to death (MTD) values were not significantly different in any instar among larvae treated with SeMNPV + Tinopal LPW and those treated with SeMNPV alone. Larval development in SeMNPV + Tinopal LPW treated larvae was retarded, in second and fourth instars, compared with controls or larvae treated with SeMNPV alone. The OB yields from SeMNPV treated larvae were almost 1.6-fold greater in second instars (9.3 x 10(6) OBs/larvae), and 1.9-fold greater in fourth instars (1.9 x 10(8) OBs/larvae), than those obtained in larvae treated with SeMNPV + Tinopal LPW. The addition of 1% Tinopal LPW to the virus suspension did not alter the genotypic composition of viral progeny during four successive passages of the virus.     

棉铃虫和甜菜夜蛾中肠丝氨酸蛋白酶活性测定以及活化、降解Cry1Ac毒素分析

昆虫中肠对Bt原毒素活化与对活化毒素降解的变化被认为是害虫对Bt产生的机制之一,研究比较棉铃虫Helicoverpa armigera(Hübner)与甜菜夜蛾Spodoptera exigua(Hübner)的中肠液、BBMV蛋白酶的活性,通过SDS-PAGE分析2种昆虫对原毒素的活化速度与对活化毒素的降解速度。2种昆虫的中肠液蛋白酶活性均显著高于BBMV蛋白酶活性,中肠液与BBMV均能迅速活化原毒素并继续降解活化后的毒素,与中肠液相比,BBMV对原毒素的活化与对活化毒素的降解均慢于中肠液,甜菜夜蛾对毒素的活化与降解又慢于棉铃虫。另外,还测定抑制剂对中肠液蛋白酶活性的抑制作用,结果表明,各抑制剂对棉铃虫和甜菜夜蛾相应酶活性的抑制表现出相同的趋势,TLCK对丝氨酶蛋白酶具较好的抑制作用,而PMSF对胰蛋白酶的抑制作用次之,TPCK对胰凝乳蛋白酶的抑制作用较弱。     

棉铃虫和甜菜夜蛾中肠丝氨酸蛋白酶活性测定以及活化、降解CrylAc毒素分析

昆虫中肠对Bt原毒素活化与对活化毒素降解的变化被认为是害虫对Bt产生的机制之一,研究比较棉铃虫Helicoverpa armigern（Hǔbner）与甜菜夜蛾Spodoptera exigm（Hǔbner）的中肠液、BBMV蛋白酶的活性,通过SDS-PAGE分析2种昆虫对原毒素的活化速度与对活化毒素的降解速度。2种昆虫的中肠液蛋白酶活性均显著高于BBMV蛋白酶活性,中肠液与BBMV均能迅速活化原毒素并继续降解活化后的毒素,与中肠液相比,BBMV对原毒素的活化与对活化毒素的降解均慢于中肠液,甜菜夜蛾对毒素的活化与降解又慢于棉铃虫。另外,还测定抑制剂对中肠液蛋白酶活性的抑制作用,结果表明,各抑制剂对棉铃虫和甜菜夜蛾相应酶活性的抑制表现出相同的趋势,TLCK对丝氨酶蛋白酶具较好的抑制作用,而PMSF对胰蛋白酶的抑制作用次之,TPCK对胰凝乳蛋白酶的抑制作用较弱。     

Indirect Chilling Injury of Spodoptera exigua in Response to Long-Term Exposure to Sublethal Low Temperature

We report indirect chilling injury, which is caused by the long-term exposure to the low temperature above freezing point, found in the beet armyworm, Spodoptera exigua. Short (minute or hour) exposure to 5°C was not lethal to all stages of S. exigua. However, several day-exposure to 5°C gave significant nonfreezing injuries such as low egg hatchability, retarded larval development, and low pupation rates. Even though the larvae did not develop at 5°C, they used up their major nutrient reserves significantly. The mechanism of the indirect chilling injury of the beet armyworm was discussed on the basis of the oxidative stress hypothesis.     

Possible involvement of gut-lumen bacteria in in-vivo proteolytic degradation of Bacillus thuringiensisδ-endotoxins

Larval gu juice from aseptically reared beet armyworm, Spodoptera exigua , exhibited lowered processing activity towards the parasporal inclusion proteins of Bacillus thuringiensis as compared with that from normal larvae. Of the seven aerobic bacteria predominantly found in guts of normal larvae, a Bacillus isolate showed marked proteolytic activity against inclusion proteins. The results suggest the possible participation of gut-lumen micro-organisms in in-vivo degradation and processing of B. thuringiensis δ-endotoxins.     

Effect of biological and chemical insecticides on Spodoptera species (Lep., Noctuidae) and marketable yields of tomatoes

Various biological and chemical insecticide treatments were evaluated against beet armyworm Spodoptera exigua (Hübner), yellowstriped armyworm Spodoptera ornithogalli (Guenée) and southern armyworm Spodoptera eridania (Cramer) to determine their effects on Spodoptera species, fruit quality and marketable yields of tomatoes Lycopersicon esculentum Mill. Biological insecticides included several Bacillus thuringiensis (Berliner) products including Condor^® OF, Dipel^® 2X, Javelin^® WG, Bactec^® III, Biobit^® FC, Cutlass^® WP and Lepinox^® G. Other biological treatments included a baculovirus, SeNPV isolated from S. exigma , and an entomophagous nematode, Steinernema carpocapsae Weiser. Chemical treatments consisted of several insecticides from various classes including a carbamate (methomyl), pyrethroid (fenpropathrin) and an organophosphate (chlorpyrifos). A natural extract from the neem tree azadirachtin and an untreated control were also included in the evaluation studies. Population densities of S. exigua were below the economic threshold level in control plots and there were no significant differences for small, medium and large larvae. Densities of S. ornithogalli and S. eridania larvae exceeded the threshold level and significant treatment differences were observed in their populations. Fruit injuries were significantly higher in nonefficacious treatments that included S. carpocapsae , SeNPVs and untreated controls. Average weight per fruit was not significantly affected by treatment rates of applications, but total marketable yields were significantly higher in efficacious biological, chemical and combination treatments compared with the control.     

寄主植物对甜菜夜蛾三龄幼虫抗寒力的影响

寄主植物是影响昆虫抗寒性的主要因子之一。研究了不同温度下甜菜夜蛾Spodoptera exigua(Hübner)3龄幼虫取食小白菜、甘蓝、葱和菠菜后,对过冷却能力和体内冷冻保护剂的影响。结果表明,寄主植物对甜菜夜蛾3龄幼虫的过冷却能力有显著性影响,其中以取食甘蓝的幼虫过冷却点最低。温度和寄主植物对其过冷却点、结冰点和虫体含水量有明显的交互作用。寄主植物对其体内的海藻糖含量有显著性影响,而对甘油和糖原含量没有显著性影响。温度和寄主植物仅对海藻糖含量有显著的交互作用。随着温度的升高,取食不同寄主的幼虫体内海藻糖和糖原含量的变化趋势完全相反,认为海藻糖是由糖原转化而来。研究结果提示冬季合适的寄主植物有利于甜菜夜蛾低龄幼虫越冬。     

不同食物对甜菜夜蛾生长发育参数的影响

选择上海地区近年甜菜夜蛾Spodoptera exigua(Hübner)发生比较严重的甘蓝、豇豆、大葱、芦笋4种寄主植物,在温度(27±1)℃,相对湿度70%±5%,光照L:D=14:10的条件下研究了不同寄主植物对甜菜夜蛾发育特征的影响。结果表明,不同寄主植物饲喂甜菜夜蛾,甜菜夜蛾幼虫发育历期、存活率、蛹重、成虫寿命、净生殖力和内禀增长率等参数在寄主植物间有显著差异。用甘蓝饲喂的甜菜夜蛾雌虫产卵量明显高于取食大葱和芦笋的。同样,取食甘蓝的甜菜夜蛾蛹重、净生殖力和种群内禀增长率等参数明显高于取食大葱和芦笋的,说明甘蓝与其他寄主植物相比提供了较好质量的食物。     

Pro-active management of beet armyworm (Lepidoptera: Noctuidae) resistance to tebufenozide and methoxyfenozide: baseline monitoring,risk assessment,and isolation of resistance

Susceptibility to tebufenozide and methoxyfenozide of beet armyworm [Spodoptera exigua (Hübner)] from the southern United States and Thailand was determined through exposure of first and third instars to dipped cotton leaves. Among the field populations evaluated, tebufenozide LC50 values for first and third instars, respectively, ranged from 0.377 to 4.41 and 4.37-46.6 microg (AI) /ml of solution. Methoxyfenozide LC50 values for first and third instars of field populations ranged from 0.058 to 0.487 and 0.601-3.83 microg (AI)/ml of solution. A Thailand field strain exhibiting reduced susceptibility to both compounds was subjected to intense laboratory selection for three nonconsecutive generations. At the LC50 and LC90, selected Thailand strains were 45-68 times and 150-1,500 times less susceptible to tebufenozide and 340-320 times and 120-67 times less susceptible to methoxyfenozide as first and third instars, respectively, when compared with the laboratory reference strain. Among the U.S. field populations evaluated, ones from Belle Glade, FL, and Florence, SC, were generally the most susceptible and ones from Maricopa and Parker, AZ, were the least susceptible. Selection of the Thailand field strain with tebufenozide reduced susceptibility to both compounds, and selection of Thailand strains previously pressured with either compound further reduced susceptibility to both, suggesting at least some commonality of resistance mechanism. Characterization of this resistance will provide information that will be helpful for pro-active management of resistance for this valuable group of insecticides.     

Enhancement in activity of homologous and heterologous baculoviruses infectious to beet armyworm (Lepidoptera: Noctuidae) by an optical brightener

The nuclear polyhedrosis virus (NPV) from the beet armyworm, Spodoptera exigua (Hübner) (SeMNPV), was the most active virus tested against the beet armyworm (LC50 = 4.1 PIBs/mm2), followed by nuclear polyhedrosis viruses from the alfalfa looper, Autographa californica (Speyer) (AcMNPV; LC50 = 92.6 PIBs/mm2), and the celery looper, Anagrapha falcifera (Kirby) (AfMNPV; LC50 = 195.7 PIBs/mm2). In the case of the nuclear polyhedrosis virus from the bollworm, Helicoverpa armigera (Hübner), LC50s could only be obtained for five/six replicates, whereas LC50s could only be obtained for two/six replicates for the nuclear polyhedrosis virus from the wax moth, Galleria mellonella (L.) (GmMNPV). When an optical brightener Tinopal LPW was added to virus suspensions, LC50 values were reduced by 130-fold for both SeMNPV and AcMNPV and by 300-fold for AfMNPV. The addition of Tinopal LPW greatly increased the activities of HaMNPV and GmMNPV. In terms of speed of kill, Tinopal LPW reduced the LT50s for all nuclear polyhedrosis viruses by 30-40%.     

Expression of the crystal protein gene under the control of the alpha-amylase promoter in Bacillus thuringiensis strains.

The expression of an insecticidal crystal protein gene of Bacillus thuringiensis under the control of the alpha-amylase gene promoter was investigated. The cryIC gene, which encodes a protein known to have a unique activity against Spodoptera (armyworm) species, was used in this investigation. The cryIC gene was placed, along with the alpha-amylase promoter from B. subtilis, in a B. thuringiensis-derived cloning vector, generating a pair of recombinant plasmids, pSB744 and pSB745. The cloning vector that contains the minimal replicon of B. thuringiensis subsp. kurstaki HD73 is stably maintained in a variety of B. thuringiensis strains, as previously reported by Gamel and Piot (Gene 120:17-26, 1992). The present study confirmed that the recombinant plasmids are also stably maintained in B. thuringiensis subsp. kurstaki Cry-B and HD73 growing in media without selection pressure for at least 48 h. The cryIC gene on the recombinant plasmids were notably expressed at high levels in both recombinant strains. Expression of the introduced cryIC gene on the recombinant plasmid in B. thuringiensis subsp. kurstaki HD73 did not impair expression of the resident cryIA(c) gene. The CryIA(c) protein is known to have a high level of activity against loopers such as Trichoplusia ni (the cabbage looper). As a result of coexpression of the introduced cryIC gene and the resident cryIA(c) gene, recombinant strain HD73 acquired an additional insecticidal activity against Spodoptera exigua (the beet armyworm) whereas the original activity level against T. ni was maintained.     

寄主植物-甜菜夜蛾-寄生蜂三级营养关系的研究进展

综述了近年来甜菜夜蛾Spodoptera exigua (Hübner)、寄主植物和寄生蜂互作关系方面的研究进展。介绍了甜菜夜蛾取食诱导的植物抗虫性产生的原因和机制;阐述了诱导植物产生抗性的甜菜夜蛾激发子volicitin的合成途径和功能,以及虫害诱导的植物挥发物和蛋白酶抑制剂对甜菜夜蛾及其寄生蜂的生态学功能;展望了植物诱导抗虫性在甜菜夜蛾的生物防治和新型抗虫品种开发等领域的应用前景。     

Host plant resistance in romaine lettuce affects feeding behavior and biology of Trichoplusia ni and Spodoptera exigua (Lepidoptera: Noctuidae)

Lettuce quality and yield can be reduced by feeding of several lepidopterous pests, particularly cabbage looper, Trichoplusia ni (Hübner), and beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). Host plant resistance to these insects is an environmentally sound adjunct to conventional chemical control. In this study we compared the survival, development, and feeding behavior of cabbage looper and beet armyworm on two romaine lettuce cultivars, resistant 'Valmaine' and susceptible 'Tall Guzmaine'. Larval mortality of both species was significantly higher on resistant Valmaine than on susceptible Tall Guzmaine. The average weight per larva after feeding for 1 wk on Tall Guzmaine plants was 6 times (beet armyworm) and 2 times (cabbage looper) greater than that of larvae feeding on Valmaine plants. Significant reduction in larval growth on Valmaine compared with that on Tall Guzmaine resulted in a 5.9- (beet armyworm) and 2.6-d (cabbage looper) increase in larval duration and almost a 1-d increase in pupal duration. Average pupal and adult weights and successful pupation of cabbage looper and beet armyworm were reduced on Valmaine compared with Tall Guzmaine. The sex ratio of progeny did not deviate from 1:1 when larvae were reared on either Valmaine or Tall Guzmaine. The fecundity of cabbage looper and beet armyworm adults that developed from larvae reared on Valmaine was about one-third that of adults from Tall Guzmaine, but adult longevity did not significantly differ on the two lettuce cultivars. The two insect species showed different feeding preferences for leaves of different age groups on Valmaine and Tall Guzmaine. Cabbage loopers cut narrow trenches on the leaf before actual feeding to block the flow of latex to the intended site of feeding. In contrast, beet armyworms did not trench. The different feeding behavior of the two species on Valmaine may explain the superior performance of cabbage looper compared with beet armyworm.     

Effects of neem-based insecticides on beet armyworm （Lepidoptera： Noctuidae）

Abstract Three commercial neem [ Azadirachta indica A. Juss (Meliaceae)]-based insecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder, were evaluated for oviposition deterrence, antifeedant effect on larvae, and toxicity to eggs and larvae of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), on cotton leaves in the laboratory. Oviposition deterrence in no-choice, and two- and fivechoice assays, was observed for the neem-based insecticide treatments when compared with a non-treated control. Neem-based insecticides also deterred feeding by beet armyworm larvae. Direct contact with neem-based insecticides decreased the survival of beet armyworm eggs. Survival of beet armyworm larvae fed for 7 days on leaves treated with neembased insecticides was reduced to 27, 33, 60, and 61% for neem leaf powder, Ecozin, Agroneem, and Neemix, respectively. Possibilities for adoption of neem-based insecticides in commercial cotton for beet armyworm control are discussed.     

Enhanced production of insecticidal proteins in Bacillus thuringiensis strains carrying an additional crystal protein gene in their chromosomes.

A two-step procedure was used to place a cryIC crystal protein gene from Bacillus thuringiensis subsp. aizawai into the chromosomes of two B. thuringiensis subsp. kurstaki strains containing multiple crystal protein genes. The B. thuringiensis aizawai cryIC gene, which encodes an insecticidal protein highly specific to Spodoptera exigua (beet armyworm), has not been found in any B. thuringiensis subsp. kurstaki strains. The cryIC gene was cloned into an integration vector which contained a B. thuringiensis chromosomal fragment encoding a phosphatidylinositol-specific phospholipase C, allowing the B. thuringiensis subsp. aizawai cryIC to be targeted to the homologous region of the B. thuringiensis subsp. kurstaki chromosome. First, to minimize the possibility of homologous recombination between cryIC and the resident crystal protein genes, B. thuringiensis subsp. kurstaki HD73, which contained only one crystal gene, was chosen as a recipient and transformed by electroporation. Second, a generalized transducing bacteriophage, CP-51, was used to transfer the integrated cryIC gene from HD73 to two other B. thuringiensis subsp. kurstaki stains. The integrated cryIC gene was expressed at a significant level in all three host strains, and the expression of cryIC did not appear to reduce the expression of the endogenous crystal protein genes. Because of the newly acquired ability to produce the CryIC protein, the recombinant strains showed a higher level of activity against S. exigua than did the parent strains. This two-step procedure should therefore be generally useful for the introduction of an additional crystal protein gene into B. thuringiensis strains which have multiple crystal protein genes and which show a low level of transformation efficiency.     

甜菜夜蛾类钙粘蛋白基因全长cDNA的克隆及序列分析

昆虫中肠膜上的类钙粘蛋白(cadherin-like protein)是Bt毒素的一类重要受体,它与Bt毒素对昆虫的杀虫作用机制以及昆虫对Bt毒素的抗性等密切相关。本研究根据已报道的其它昆虫的类钙粘蛋白基因的保守区设计简并引物,应用RT-PCR和RACE技术克隆了迁飞性重要害虫甜菜夜蛾Spodoptera exigua(Hübner)类钙粘蛋白基因全长cDNA序列(命名为SeCAD,GenBank登录号为HQ647122),全长5582bp,编码1739个氨基酸,推导的氨基酸序列包括1个信号肽、1个前蛋白区、11个钙粘蛋白重复、1个近膜区、1个跨膜区和1个胞质区。预测的分子量和等电点分别为196.447ku和4.47。该蛋白与同科的大螟Sesamia inferens、蛀茎夜蛾S.nonagrioides、烟芽夜蛾Heliothi svirescens、烟夜蛾Helicover paassulta亲缘关系更近,氨基酸序列一致性分别为61.28%、60.34%、60.14%、60.08%。这些结果对于揭示转Bt基因作物对非靶标、迁飞性甜菜夜蛾的杀虫作用机制以及评价其潜在的对Bt毒素抗性机制等奠定了基础。