Susceptibility of Oriental armyworm,Mythimna separata (Lepidoptera: Noctuidae) larvae and pupae to native entomopathogenic nematodes

The Oriental armyworm, Mythimna separata Walker (Lepidoptera: Noctuidae) is a major pest of cereal crops, and its outbreaks result in complete crop loss. In this study, we tested the pathogenicity and reproductive potential of indigenous entomopathogenic nematodes (EPNs), Heterorhabditis indica Poinar, Karunakar, & David NBAIIH38, Steinernema abbasi Elawad NBAIISa01, S. carpocapsae Weiser NBAIISc05 and S. siamkayai Stock, Somsook and Reid NBAIRS92 against larval and pupal stages of M. separata under laboratory conditions. Steinernema carpocapsae caused significantly greater mortality in second- and fourth-instar larval stages than other EPNs species. Steinernema carpocapsae caused greatest mortality 100% in larval stages and 75% in pupal stages. Significant differences were observed in the lethal concentration values (LC₅₀ and LC₉₀) of EPNs species against different stages of M. separata. Differences in penetration and multiplication in the fourth-instar larval stages of M. separata were observed amongst the EPNs species. However, further studies are needed to reveal the field performance of EPN isolates tested to be included in the IPM programme of M. separata.     

松油烯-４-醇对粘虫幼虫的生物活性

测定了杀虫植物砂地柏Sabina vulgaris Ant.的精油中主杀虫成分-松油烯-4-醇（terpinen 4.01）对粘虫Mythimna separata Walker幼虫的生物活性。结果表明,松油烯- 4-醇对粘虫主要表现为熏蒸作用,对粘虫3龄幼虫24 h的熏蒸LC₅₀为5.3473 μL/L ;还具一定触杀作用,对粘虫4龄幼虫24 h的LD₅₀为147.8 μg/虫。试虫的中毒症状可明显地分为兴奋、痉挛、麻痹和死亡4个阶段,而麻痹的部分试虫有复苏现象。可明显抑制Na⁺ ,K⁺ATP酶的活性,在兴奋期、痉挛期、麻痹期和复苏期,抑制率介于21.28%～34.92% 之间。离体条件下对Na⁺,K⁺ATP酶的I₅₀为133.75 μg·mL^-1;对AChE活性有一定的影响;对酯酶,在兴奋期,酶活力为对照的7.0%,在麻痹期则为对照的1.33倍,而复苏期试虫的酯酶活力与对照相当。     

粘虫类钙粘蛋白基因的克隆、序列分析及时空表达

昆虫中肠膜类钙粘蛋白（cadherin-like protein, CLP）是苏云金芽孢杆菌Bacillus thuringiensis (Bt)毒素的重要受体之一, 与Bt毒素的杀虫作用机制以及昆虫对Bt毒素的抗性等密切相关。本研究应用RT-PCR和RACE技术, 克隆了迁飞性重要害虫粘虫Mythimna separata类钙粘蛋白基因全长cDNA序列（命名为Msclp, GenBank登录号为JF951432）, 全长5 642 bp, 编码1 757个氨基酸, 推导的氨基酸序列具有昆虫类钙粘蛋白的特征结构, 包括1个信号肽、 1个前蛋白区、 12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196.786 kD和4.5。该蛋白与同科的烟夜蛾Helicoverpa assulta、 烟芽夜蛾Heliothis virescens、 棉铃虫Helicoverpa armigera及甜菜夜蛾Spodoptera exigua的类钙粘蛋白亲缘关系最近, 氨基酸序列一致性分别为61.77%, 61.66%, 61.26%和58.14%。荧光定量RT-PCR分析表明, 该类钙粘蛋白基因在不同龄期的粘虫幼虫中表达量差异极显著(P<0.01), 其中4龄幼虫相对表达量最高, 但与3龄、 6龄幼虫并没有显著性差异; 1和2龄幼虫表达量最低; 表达部位主要在粘虫中肠, 在中肠以外的虫体其他部位表达量极低。这些结果对于揭示转Bt作物对非靶标、 迁飞性粘虫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。     

粘虫hsc70克隆及其密度胁迫下的表达模式

【目的】昆虫种群密度的升高往往成为一种胁迫因子。粘虫在低密度下形成散居型,而在高密度下则形成群居型。本研通过比较hsc70在两型粘虫中的表达模式,究旨在探索hsc70在粘虫Mythimna separata响应密度胁迫中的作用。【方法】采用RT-PCR和RACE技术克隆粘虫hsc70cDNA全长序列,利用生物信息学软件分析该基因及其编码蛋白质的序列特性;运用实时荧光定量PCR技术(qRT-PCR)分析该基因在两型粘虫不同发育阶段(卵、1-6龄幼虫、蛹和成虫)、5龄幼虫不同组织(头、表皮、前肠、中肠、后肠和马氏管)以及群居和分离处理后mRNA表达量的变化。【结果】克隆得到的HSC70基因命名为Mshsc70(GenBank登录号:MH669276),全长cDNA长2 184 bp,开放阅读框为1 965 bp,编码653个氨基酸。序列分析发现MsHSC70具有HSP70家族典型的结构域,即IDLGTTYS(11-18aa),IFDLGGGTFDVSLL (198-211 aa)和IVLVGGSTRIPKVQQ (341-355 aa)。序列比对结果显示,MsHSC70与斜纹夜蛾Spodopteralitura,棉铃虫Helicoverpaarmigera,大螟Sesamiainferens、甘蓝夜蛾Mamestra brassicae HSC70的相似性高达99%;基于HSC70的系统发育分析显示,粘虫与夜蛾科(Noctuidae)昆虫的亲缘关系最近。Mshsc70在两型粘虫的各个发育阶段均表达,hsc70的表达量在1龄和5龄中的表达量较散居型显著上调,而在2-3龄中的表达量显著下调。除表皮和前肠外,群居型粘虫的其他组织中hsc70的表达量显著高于散居型。散居型粘虫经群聚饲养36h后,hsc70显著上调表达,表达量是对照的3.17倍,而群居型粘虫经分离饲养36 h后,hsc70的表达量与对照无显著差异。【结论】粘虫的种群密度是决定粘虫hsc70表达的一个重要因子。     

A flagellate protozoan from Mythimna separata (Lepidoptera: Noctuidae)

Abstract

A trypanosomatid flagellate, Herpetomonas sp., is recorded from an adult Mythimna separata (Walker) (Lepidoptera: Noctuidae). Promastigote, paramastigote, and opisthomastigote stages measured 3.4–12 × 1.3–4.3 μm, Giemsastained, with flagella measuring 13.8–18.7 μm. A few amastigotes (3.9–8.3 × 3.7–6.7 μm) were also observed. Fourteen larvae fed with a suspension of flagellates were found later to be infected with the protozoan. No flagellate infections were found in the hymenopteran parasitoid, Apanteles ruficus (Haliday), or the hyperparasitoid, Trichomalopsis sp.     

黑化粘虫的形态特征及其遗传模式

本文首次研究报道了黑化粘虫Mythimna separata的形态特征及其遗传模式。所获的结果表明,黑化型与正常型粘虫的外部形态特征差异主要表现在成虫期。与正常型粘虫相比,黑化粘虫的成虫体色几乎全部变黑,正常型成虫所具有的黑色特征在黑化粘虫中已完全看不见,其他的颜色特征也由于黑化而产生了变异。卵、幼虫和蛹的颜色与正常型的没有明显的区别,只是黑化型的蛹在将羽化时的体色比正常型的深。黑化粘虫的遗传遵循孟德尔的隐性遗传规律,由位于常染色体上的单基因控制。这些结果表明,黑化型与正常型粘虫虽然仍属于同一个种,但黑化粘虫已经演变成了不同的基因型。最后,对黑化粘虫产生的原因及其在进化上的适应意义进行了讨论。     

The role of nectar plants in severe outbreaks of armyworm Mythimna separata (Lepidoptera: Noctuidae) in China

The period from March to mid April, when oriental armyworm Mythimna separata (Walker) moths migrate from South China to Central China over several nights, is an important window of time in annual armyworm population increase. The presence of nectar sources along the pathway of the migratory population is a prerequisite for moths to reach target habitats and lay eggs. Using flowering periods and geographic distributions, the major spring nectar plants suitable for M. separata moths were identified from among 102 species/varieties of apicultural nectar plants. The nectar plants proposed as important to M. separata include milk vetch Astragalus sinicus L., rape Brassica napa L. and six other species. Spearman's rank correlation analyses were conducted between the annual population size of M. separata and the acreages of milk vetch and rape in the daily stopover areas for migrating populations of M. separata during 1950-1979. The Spearman's coefficient between milk vetch and M. separata was 0.6259 and the correlation was highly significant (P<0.001). Further regression analysis with data from 1950-1979 and from 1980-1992 also revealed a close relationship between annual acreage of damaged crops/wheat and acreage of milk vetch. These results strongly suggest that the unprecedented enlargement in the geographic distribution of milk vetch from Central China into South China was the key factor in the frequent severe oriental armyworm outbreaks that occurred during 1966-1977. This is thought to be the first report in the world that reveals the key role of nectar sources in long distance, regional scale, migration of moths. The argument for the key role of milk vetch is supported by the simultaneous decline in the level of damage inflicted by M. separata and the acreage of milk vetch after 1980.     

Influence of green light at night on Juvenile hormone in the oriental armyworm Mythimna separata (Lepidoptera: Noctuidae)

The oriental armyworm Mythimna separata is an agricultural insect pest in Eastern Asia. Mythimna separata moths have a high phototactic response to green (520 nm) light. The biological characteristics of insects living under light of a specific wavelength at night can change and, accordingly, Juvenile hormone (JH) levels may be influenced by this light. The present study evaluates changes in the total JH levels at different developmental stages (larvae, pupae and adults) of M. separata reared under green light with different exposure periods at night (or dark period). The results show that, when the exposure time per day of the green light at night is extended, the JH levels in the final‐instar larvae (22 days) and older age pupae (8 days) are significantly reduced, and the JH levels in earlier age pupae (4 days) and adults (3, 6 and 9 days) are significantly increased, compared with groups not exposed to green light. Additionally, the JH level of male moths significantly differs from that of the female moths. We suggest that the JH level of M. separata insects could be regulated by the green light at night (or dark period). The findings of the present study will help to explain the relationship between the light environment and biological characteristics in nocturnal moths.     

Influence of green light illumination on several enzymes involved in energy metabolism in the oriental armyworm,Mythimna separata (Lepidoptera: Noctuidae)

The oriental armyworm, Mythimna separata Walker, is an important insect pest in eastern Asia. Green (520 nm) light with an exposure time of >30 min can result in a stronger phototactic response than the wavelengths of other lights in M. separata moths. The present study was mainly focused to estimate the activities of several enzymes (such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glycerol-3-phosphate dehydrogenase (GPDH), lactate dehydrogenase (LDH) and 3-hydroxyacyl-CoA dehydrogenase (HOAD)) involved in the energy metabolism and a ratio of HOAD to GAPDH activity in M. separata moths exposed to the green light for different exposure times. Our results showed that when M. separata moths were exposed to the green light for 30 min, the activities of the two enzymes (GPDH and HOAD) and as well as the ratio of HOAD to GAPDH activity were significantly elevated. The activity of LDH was significantly increased in the moths exposed for 60 min. Furthermore, significant differences in enzyme activities between the male and female moths were recorded in 45 min exposure time group of the GAPDH, all light treatment groups of the LDH, and 45 min group of the ratio of HOAD to GAPDH activity, respectively. We suggest that when M. separata adult moths are exposed to the green light, these enzymes can be activated to produce energy for starting the phototactic behavior to the green light. Our findings may provide a theoretical basis for elucidating a reason of the phototactic behavior of nocturnal moths.     

天然产物梣酮对粘虫围食膜的影响

【目的】梣酮是从芸香科植物白鲜Diatamnus dasycarpus根皮中分离出的一种化合物, 对试虫表现出胃毒活性。本研究旨在检测梣酮对粘虫Mythimna separata 6龄幼虫中肠围食膜的影响, 从而进一步阐明梣酮的杀虫作用机理。【方法】经活体及离体处理, 通过生化分析和扫描电镜观察等方法, 研究了梣酮处理对粘虫幼虫中肠围食膜糖含量, 蛋白质含量和组分以及围食膜表面结构的影响。【结果】梣酮(20 mg/mL)活体处理降低了粘虫6龄幼虫围食膜的蛋白质含量, 却使糖含量升高。活体(20 mg/mL梣酮)及离体(8 mg/mL梣酮)处理条件下, 围食膜糖含量分别为对照组的1.75倍及2.17倍。SDS-PAGE结果显示, 离体及活体条件下经梣酮处理, 围食膜部分蛋白质降解。围食膜解剖扫描电镜观察表明, 梣酮处理可造成围食膜微纤丝排列紊乱。【结论】天然产物梣酮处理对粘虫中肠围食膜的糖含量及蛋白质含量和组分有影响,且改变了围食膜表面结构。本研究为深入地研究梣酮杀虫作用机理奠定了基础。     

Oviposition and larval dispersal of the common armyworm,Mythimna convecta (Walker) (Lepidoptera: Noctuidae)

The common armyworm, Mythimna convecta (Walker), is a pest of cereal crops and pasture grasses in Australia. During autumn, egglaying in grasslands commonly occurs before plant growth commences. The possible association between oviposition and dried grasses was investigated in field studies of larval distribution in a pasture and a crop habitat, and in laboratory studies of oviposition site preferences and the mode of dispersal of newly hatched first instar larvae. A comparison of a green grass pasture with and without a component of dried grass showed that highest densities of M. convecta larvea. were found in the former. In the laboratory, egg batches were laid between plant parts in close contact, such as between the stem and leaf axil and between seeds in the seed head. The crevices in dried plant material and seed-heads were significantly more acceptable for oviposition than in green foliage. Oviposition in dried plant material enables M. convecta to rapidly colonize ephemeral grasslands immediately after rains when the neonate larvae can disperse and feed on new vegetative growth. Shortly after hatching, 93% of first instar larvae used fine silken threads for aerial dispersal in 0.5 m s^-1 air currents and 43% were blown a distance of more than 1.0 m. In the field, sticky traps caught larvae dispersing in all directions from a central source, and indicated that approximately 30% were transported 2 m after 7 days of light to medium breezes. Terminal velocities of newly hatched larvae were 20–130 cm s^-1, depending on the length of the trailing thread.     

Cry1Ac毒蛋白对粘虫生长发育、繁殖及飞行能力的影响

为了更全面地评价转基因作物对粘虫Mythimna separata (Walker)（鳞翅目: 夜蛾科）的影响, 在室内用生测法研究了粘虫初孵幼虫连续取食含不同浓度的Cry1Ac毒蛋白的人工饲料后, 其生长发育、繁殖及飞行能力的变化。结果表明: 取食0（对照）, 3, 6, 12, 24, 48和96 μg/g Cry1Ac毒蛋白人工饲料6 d后的幼虫头宽、 体长、 18 d后的体重随着毒蛋白浓度的升高显著降低, 幼虫发育历期显著延长, 死亡率显著升高。取食含毒蛋白浓度>12 μg/g饲料的幼虫不能正常化蛹; 取食含0, 3和6 μg/g毒蛋白饲料的幼虫能正常化蛹、 羽化, 化蛹率随着毒蛋白浓度的升高而显著降低、 蛹历期显著延长; 取食含0, 3和6 μg/g毒蛋白饲料的幼虫羽化的成虫繁殖能力有显著差异, 产卵前期随毒蛋白浓度的升高显著延长, 产卵量显著降低; 而1日龄成虫飞行能力（飞行距离、 时间和速度）则随毒蛋白浓度的升高显著降低。这些结果表明, Cry1Ac毒蛋白对粘虫的生长发育、 繁殖及飞行具有显著影响, 从而为完善转Bt作物的生态安全性风险评估提供了重要的实验依据。     

Suitability assessment of three Trichogramma species in the control of Mythimna separata (Lepidoptera: Noctuidae)

Mythimna separata (Walker) is a serious cosmopolitan pest. Trichogramma species have been used worldwide as biological control agents of lepidopteran pests. However, no data on the control efficiency of Trichogramma species on this pest have been reported. We evaluated the suitability of M. separata eggs for three Trichogramma species, Trichogramma dendrolimi Matsumura, T. ostriniae Pang et Chen and T. japonicum Ashmead, and compared the suitability with that of Corcyra cephalonica (Stainton) eggs. The parasitism rate, development time, emergence rate, female proportion, body size and egg load of female offspring indicated that the M. separata egg is a suitable host for the three Trichogramma species. On the other hand, the non‐emergence rate and the relationship between egg load and body size reflected that M. separata eggs are less suitable for the three Trichogramma species than C. cephalonica eggs. Egg resorption occurred in T. japonicum 4 days after emergence.     

Cry1Ac和Cry2Ab杀虫蛋白对粘虫幼虫生长发育的影响

【目的】为探究Bt杀虫蛋白对次要靶标害虫粘虫Mythimna separata (Walker)(鳞翅目:夜蛾科)的杀虫活性及对其生长发育的影响。【方法】本文通过浸叶法饲喂初孵及2龄末粘虫不同剂量的Cry1Ac及Cry2Ab杀虫蛋白后,观察其死亡率,称量幼虫重,并统计了幼虫历期、化蛹率、蛹重、蛹期、蛹的羽化率、畸形率等指标。【结果】初孵幼虫取食浸泡含16、64、128μg/mLCry1Ac及Cry2Ab的玉米叶片后,随着时间的延长及浓度的增加,死亡率逐渐增加,且Cry1Ac杀虫蛋白对粘虫的生物活性高于Cry2Ab蛋白,在128μg/mL浓度下,取食Cry1Ac和Cry2Ab蛋白13d时的死亡率分别达到了65%及60%。取食两种蛋白后,初孵幼虫和2龄末幼虫重量均受到显著抑制,短期取食两种蛋白对幼虫历期、化蛹率、蛹重、蛹期、蛹的羽化率、畸形率没有影响。【结论】取食Cry1Ac和Cry2Ab杀虫蛋白后,对初孵幼虫有很好的杀虫活性,且Cry1Ac杀虫活性高于Cry2Ab杀虫蛋白;短期饲喂两种杀虫蛋白时,对2龄粘虫后期生长影响不大。本文结果为转Bt基因作物更好的应用于粘虫的防治提供了理论基础。     

东北地区粘虫的季节性迁飞行为(英文)

粘虫Mythimna separata是我国农业生产上的重要害虫, 为了明确其季节性迁飞行为参数, 本研究采用垂直监测昆虫雷达（vertical-looking radar, VLR）及相关辅助设备的长期自动观测, 结合基于GIS的大区环流和轨迹模拟, 调查分析了2005年东北地区粘虫季节性迁飞行为。结果表明： 粘虫在不同季节和夜间不同时间空中飞行高度具有明显差异, 空中飞行行为受气象条件尤其是空中风场影响较大; 春季和秋季主要借助气流运载进行大规模长距离迁飞, 夜间持续飞行时间可达9 h, 多数个体能完成整夜飞行, 春季迁飞高度主要在300~600 m, 秋季飞行高度相对较低主要在300 m以下和400~500 m。夏季雷达回波有明显的成层现象, 最高可达1 000 m, 主要集中在500 m和700 m两个高度层。轨迹分析显示： 5月29日由山东潍坊、 临沂等虫源地起飞的黏虫, 顺西南气流越海迁飞, 6月1日在气旋天气影响下, 在吉林省白城等地降落; 7月中旬主要为当地黏虫受对流天气影响进行短距离迁飞扩散; 9月11日虫源来自内蒙古呼伦贝尔, 顺西北气流向吉林省东南方向迁飞。研究结果为东北地区粘虫的有效防控提供了技术支撑。     

Autumn migration of Mythimna separata (Lepidoptera: Noctuidae) over the Bohai Sea in northern China

The autumn migration of Mythimna separata (Walker) (Lepidoptera: Noctuidae) across the Bohai Sea was observed with a scanning entomological radar and a searchlight trap at Beihuang, an island located in the center of the Bohai Gulf of northern China, in 2003-2006. During the autumn migration, M. separata flew at the altitudes of 50-500 m, with a displacement speed of 4-12 m/s, toward the southwest. Variations of area density of the radar targets and of catches in the searchlight trap through the night indicated that the flight duration of M. separata was approximately 10 h. Based on these observations, M. separata that originated in northeastern China (i.e., Liaoning, Jilin, and Heilongjiang provinces and part of the Inner Mongolia autonomous region) could immigrate into eastcentral China and subsequently to southern China (i.e., Fujian, Guangdong, and Guangxi provinces) within a week for overwintering.     

Cry1Ac杀虫蛋白对粘虫中肠几种酶活性的影响

为阐明Bt杀虫蛋白对次要靶标害虫粘虫Mythimna separata (Walker) （鳞翅目： 夜蛾科）的生理学影响, 本研究分析比较了粘虫高龄幼虫在室内取食低剂量Cry1Ac杀虫蛋白6, 12, 24和36 h后, 其体内主要的解毒酶（酯酶和谷胱甘肽-S-转移酶）、 保护酶（超氧化物歧化酶、 过氧化氢酶和过氧化物酶）和中肠蛋白酶（总蛋白酶、 强碱性类胰蛋白酶、 弱碱性类胰蛋白酶和类胰凝乳蛋白酶）等活性的变化。结果表明, 取食Cry1Ac杀虫蛋白后, 粘虫幼虫体内相关酶活力呈现不同的变化趋势： （1）酯酶、 谷胱甘肽-S-转移酶、 过氧化物酶(POD)、 类胰蛋白酶和类胰凝乳蛋白酶活力较对照显著降低（P<0.05）; （2）超氧化物歧化酶(SOD) 活力较对照显著升高（P<0.05）; （3）过氧化氢酶(CAT) 活力于6, 12和24 h显著低于对照（P<0.05）, 36 h时显著高于对照（P<0.05）。结果提示Cry1Ac杀虫蛋白主要通过抑制粘虫幼虫中肠解毒酶和蛋白酶的活性, 扰乱SOD, CAT 和POD 3种保护酶的动态平衡而干扰幼虫的正常生理代谢, 从而起到毒杀粘虫的作用。     

粘虫谷氨酰胺转胺酶(MsTGase)活力测定条件的正交优化及其在幼虫体内的分布

【目的】本研究旨在优化Grossowicz氧肟酸比色法测定粘虫Mythimna separata谷氨酰胺转胺酶(Ms TGase)活力的组合条件,以Ms TGase酶活力为依据分析其在不同龄期幼虫体内的分布规律。【方法】取4龄粘虫幼虫,通过组织匀浆和沉析纯化制备Ms TGase,采用Grossowicz比色法测定Ms TGase酶活力,并对Grossowicz比色法的多重实验因素进行正交优化,进一步结合差速离心法分析不同龄期幼虫体内和亚细胞组分(细胞核和细胞碎片,线粒体,微粒体以及胞质溶胶)中Ms TGase酶活力。【结果】结果表明,酶浓度、底物浓度、反应体系pH值、反应温度及钙离子浓度等实验因素都对Ms TGase酶活力测定结果产生显著影响,其影响大小顺序为:酶浓度>温度> p H>底物浓度>Ca2+浓度。Ms TGase酶比活力测定的最优化条件:酶浓度20 mg/m L、底物浓度0. 04 mol/L、反应体系pH值6. 5、测定温度37℃,不添加钙离子。在1-5龄幼虫中以4龄幼虫的Ms TGase酶活力最高,其比活力也显著高于其他龄期的,且在1-5龄幼虫胞质溶胶中Ms TGase酶活力分别占各亚细胞组分酶活力总和的39%,25%,48%,60%和61%。【结论】所获得的最优化条件适用于粘虫Ms TGase酶活力测定。Ms TGase在粘虫体内呈显著的龄期表达特征和亚细胞分布规律。     

Microsatellite‐based analysis of genetic structure and gene flow of Mythimna separata (Walker) (Lepidoptera: Noctuidae) in China

The oriental armyworm, Mythimna separata, is a serious agricultural pest in China. Seasonal and roundtrip migration has recently led to sudden, localized outbreaks and crop losses. To evaluate genetic differentiation between populations in eastern and western China and elucidate gene flow, the genetic structure of 20 natural populations from nine provinces was examined using seven microsatellite markers. The results indicated high genetic diversity. However, little to moderate (0 < F_ST < 0.15) genetic differentiation was detected, and there was no correlation between genetic distance and geographical distance. Bayesian clustering analysis identified three groups whereas discriminant analysis of principal components identified ten clusters that were considered as two clear‐cut clusters and one admixed group. Gene flow occurred frequently in most population pairs, and an asymmetrical migration rate was detected in several pairwise population comparisons. The bottleneck test showed that few populations had experienced recent bottlenecks. Correspondingly, large‐scale and long‐distance migration of M. separata has caused low genetic differentiation and frequent gene exchange. Our findings are important for studying genetic evolution and help to improve predictions of M. separata outbreaks in China.     

黏虫HSP90/70组织蛋白基因的分子特征与表达特性

为解析黏虫Mythimna separata响应环境胁迫的分子机制,采用RACE和RT-PCR的方法从黏虫中克隆了1个HSP90/70组织蛋白(heat shock 90/70 organizing protein, HOP)基因,并采用qRT-PCR分析了其在多种生物和非生物胁迫下的表达特性。结果表明,MsHOP具有1个1 626 bp的开放阅读框,编码541个氨基酸,预测的分子量为61.7 kDa。序列分析表明,MsHOP主要由已报道的3个保守四肽重复结构域(TPR1, TPR2A和TPR2B)和2个天冬氨酸-脯氨酸重复基序(DP)构成。基于鳞翅目昆虫HOP构建的系统进化树显示MsHOP与棉铃虫Helicoverpa armigera HOP和烟芽夜蛾Heliothis virescens HOP的亲缘关系最近。qRT-PCR分析表明,MsHOP在黏虫所有发育时期和组织均表达,分别在5龄幼虫和雌成虫中肠的表达量最高。在30℃下处理1 h后,MsHOP的表达水平较对照显著提高,而在33℃～39℃下处理1 h后MsHOP的表达水平则与对照差异不显著。饥饿24～72 h后,MsHOP的表...