Identification of summer nectar plants contributing to outbreaks of Mythimna separata(Walker)(Lepidoptera: Noctuidae) in North China

The presence of adequate nectar sources along the migratory pathway is a prerequisite for moths of oriental armyworm, Mythimna separata, to reach target habitats and lay eggs. Identification of plant species and assessment of their suitability as wild nectar sources along the summer migration pathway of adult M. separata are critical steps in making effective forecasts of second-and third-generation armyworm outbreaks in North China. We explored five aspects of moth-nectar source relationships:(1) Field investigations in 2014 and 2015 showed that the florescence of chaste tree, Vitex negundo var. heterophylla, a primary nectar plant in apiculture, coincided with the summer migration of oriental armyworm moths. The flowers of chaste tree opened day and night and M. separata moths were found actively flying around and resting on tree.(2) Identification of moth-borne pollen by scanning electronic microscopy(SEM) micrographs in 2015 and 2016 revealed that 15.4% of 369 moths trapped by blacklight traps, 17.1% of 557 moths captured by vertical-pointing searchlight traps and 24.4% of 311 moths caught by pheromone traps were found with pollen attached to their proboscis. A total of 228 pollen-carrying individuals out of 1237 armyworm moths were captured by the three types of traps. The three highest percentages of pollen-bearing armyworm moths were carrying pollen of Toona sp.(59.65%), Ligustrum sp.(27.19%) and Syringa sp.(4.39%). In total, 14 types of pollen were detected where three were identified to species, 10 to genus and one as an unknown species.(3) Analysis of geographical distribution, flowering periods and relative abundances of candidate nectar plants suggested that Chinese toon, Toona sinensis, and privet, Ligustrum lucidum, were two important nectar plant species.(4) Analysis on relationship between pollen and ovarian development showed that 14, 15 and 10 females carrying pollen of T. sinensis had ovaries at developmental stages Ⅰ, Ⅱ and Ⅲ, respectively. Many T. sinensis pollen grains were present on the proboscises of female moths.(5) Comparison of trap effectiveness between blacklight and vertical-pointing searchlight traps indicated blacklight traps caught the highest proportion(35.2%) of female in ovarian stage Ⅴ, whereas vertical-pointing searchlight traps caught the highest proportion(43.5%) of female in ovarian stage I with additional proportions of decreasing percentages for stages Ⅱ, Ⅲ and Ⅳ. Integrated analysis on these five aspects suggests that T. sinensis is an important, suitable summer nectar source that potentially influences migration and reproduction of M. separata moths andthus contributes to outbreaks of this pest. The vertical-pointing searchlight trap was the most effective tool for monitoring the migratory flight of adult M. separata. Privet, Ligustrum lucidum, and clove, Syringa sp., are possible suitable summer nectar plants that need further study to elucidate their importance. The reason why field investigation results on chaste tree differed from the results of moth-borne pollen analyses was discussed.     

重庆地区玉米黏虫僵虫体内虫生真菌的分离鉴定

玉米黏虫(Mythimna separata)是一种常见的鳞翅目害虫,具有暴发性和迁飞性,对农作物危害严重.虫生真菌是昆虫病原微生物中的最大类群,可以有效地控制自然界中害虫的种群数量.为了防治玉米黏虫和与玉米黏虫相近的草地贪夜蛾,丰富虫生真菌菌种资源,以采自重庆江津高粱地中的玉米黏虫僵虫为实验材料,运用传统培养方法分离鉴定了6株真菌.经过形态学观察和分子生物学鉴定将这6株真菌归类于3个属,分别为镰刀菌属(Fusarium)、青霉属(Penicillium)以及鬼伞属(Coprinellus).虫生真菌能够引发昆虫感染发病,将害虫的种群数量长期控制在较低水平以下,在生物防治方面很有意义.此次分离纯化得到镰刀菌属(Fusarium)和青霉属(Penicillium)的真菌均有潜在的杀虫能力,鬼伞属(Coprinellus)真菌具有防治线虫的潜力,这些真菌对玉米黏虫和草地贪夜蛾的杀虫效果还有待于进一步的实验研究.     

Analysis on the migration of first-generation Mythimna separata (Walker) in China in 2013

Mythimna separata (Walker) is an important pest which can cause serious damages to cereal crops. In the past two decades, several heavy outbreaks have taken place in northern China. In order to develop a fine-scale method of forecasting outbreaks, population data were collected in northern China using searchlight traps and ground light traps. A background weather pattern analysis and trajectory analysis were performed via the Weather Research and Forecast (WRF) and FLEXPART models. Our results showed that heavy migration of first-generation M. separata appeared in northern China in 2013. In Yanqing District, Beijing, the cumulative number of captured adults in searchlight traps was around 250 000 and the daily maximum for trapped moths was 86 000. During the peak period, the majority of M. separata moths arrived after 00:00 every night. The sex ratio (female:male) at each monitoring site was greater than 1 and greatly fluctuated with population dynamics. During the migration peak, prevailing downdraft winds benefited M. separata moths to land passively. Trajectory simulation showed that immigrants were from Anhui, Jiangsu and Hubei provinces and most of them could continue to fly into the northeastern regions of China. These results provide technical support for fine-scale forecasting of the outbreak of M. separata at meso- and micro-scale.     

杠柳新苷P和E对粘虫和小地老虎中肠3种解毒酶的影响

为进一步探讨杠柳新苷类化合物在昆虫体内的代谢机制。比较研究高活性杠柳新苷P(Periploca sepium P,PSP)和无杀虫活性的杠柳新苷E(Periploca sepium E,PSE)对6龄粘虫幼虫(Mythimna separata)与小地老虎幼虫(Agrotis ypsilon)中肠3种代谢酶[羧酸酯酶(CarE)、谷胱甘肽-S-转移酶(GST)、细胞色素P450-O-脱甲基酶]活性的影响。结果表明:药后8h,PSP和PSE使粘虫幼虫GST活性增加,但PSP上升趋势比PSE更高。而2种化合物对试虫CarE活性均无明显影响。药后12h,PSP和PSE使粘虫中肠细胞色素P450-O-脱甲基酶酶比活力显著下降,而小地老虎中该酶活性无明显变化。因此,可推测GST可能参与昆虫对杠柳毒素的解毒作用,而细胞色素P450-O-脱甲基酶活性被杠柳毒素抑制可能是造成粘虫中毒的机制之一。     

不同水稻品种对稻纵卷叶螟生长发育、存活、生殖及飞行能力的影响

系统研究了稻纵卷叶螟在6种不同水稻品种(常规粳稻武育粳3号,杂交粳稻宁粳1号,常规籼稻TN1,杂交籼稻汕优63,超级杂交籼稻两优培九,超级杂交籼粳稻甬优9号)上取食后的发育历期、存活率、卵巢发育进度、繁殖力和飞行能力。结果表明,武育粳3号和宁粳1号能显著延长稻纵卷叶螟未成熟期的发育历期,降低其存活率,延缓卵巢发育进度,降低成虫繁殖率,并提高成虫的飞行能力;不同水稻品种间的影响存在显著差异,其影响从大到小排列为杂交粳稻>常规粳稻>常规籼稻>杂交籼稻>超级杂交稻。这说明,幼虫期营养对稻纵卷叶螟的生长发育、存活、生殖和飞行能力具有显著影响。     

利用RNAi技术沉默东方粘虫V-ATP酶H亚基研究

昆虫V-ATP酶(vacular-type ATPase)是以ATP为能量跨膜转运H+的质子泵,对其亚基进行干扰都会影响ATPase的活性,进而影响昆虫的生理生化指标。本研究利用特异性引物通过RT-PCR法扩增东方粘虫(Mythimna separata)V-ATPase H亚基的2个片段,合成相应dsRNA,通过显微注射导入3龄粘虫体内,观察试虫表型及存活情况,RT-PCR检测试虫体内H亚基的表达。结果表明,注射粘虫V-ATPase H亚基的dsRNA能够显著降低粘虫中肠V-ATPase H亚基的表达水平,直至导致目的基因沉默和粘虫死亡。本项研究成功实现东方粘虫体内V-ATPase H亚基基因沉默。     

草地贪夜蛾与玉米田其他4种常见鳞翅目幼虫第8腹节背面毛片比较

为准确鉴定玉米田5种常见鳞翅目幼虫,弄清幼虫A8背面毛片区别,通过镜下测定,详细比较玉米田5种常见鳞翅目害虫草地贪夜蛾、玉米螟、黏虫、劳氏黏虫和棉铃虫老龄幼虫第8腹节（以下简称“A8”）背面4个毛片的排列方式、大小和形状。结果表明,草地贪夜蛾4个毛片的排列近似正方形,其他4种均为矩形。毛片大小依次为：草地贪夜蛾>玉米螟>棉铃虫>黏虫>劳氏黏虫,且草地贪夜蛾、玉米螟和棉铃虫前排毛片大于后排毛片,黏虫则相反,劳氏黏虫前、后排毛片大小相当。草地贪夜蛾和黏虫幼虫4个毛片形状均为椭圆形,劳氏黏虫和棉铃虫均为圆形,而玉米螟前排毛片为圆形,后排毛片为椭圆形。     

Effects of temperatures on the development and reproduction of the armyworm,Mythimna roseilinea: Analysis using an age-stage,two-sex life table

The armyworm Mythimna roseilinea(Walker) is a major pest of grain crops in South China. So far little is known about its basic biology and ecology, making prediction of population dynamics difficult. This study examined the relationships of individual development and population growth with temperature based on an age-stage, two-sex life table of M. roseilinea reared on maize in the laboratory at 18, 21, 24, 27 and 30°C. The highest values of net reproductive rate(R_0) and fecundity were observed at 21 and 24°C, respectively. Both the intrinsic rate of increase(r) and finite rate of increase(λ) increased significantly and mean generation time(T) decreased significantly with increasing temperature. M. roseilinea was able to develop, survive and lay eggs at all temperature regimes tested. Development rates of the egg, larval, pupal, as well as the whole pre-oviposition stages had a positive linear relationship with temperature. The calculated development threshold temperatures of egg, larval, pupal, pre-oviposition and total pre-oviposition stages were 13.29, 8.39, 14.35, 7.42, and 12.24°C, respectively, and their effective accumulated temperatures were 63.59, 445.00, 211.11, 89.02, and 698.95 degree-days, respectively. These results provide insight into temperature-based phenology and population ecology of this insect pest and will allow population prediction and management available in the field.     

近零磁场下灰飞虱转录表达分析稳定性内参基因筛选

【背景】 地磁场（geomagnetic field,GMF）并不是稳定不变的,其随时间和空间时刻变化。目前,随着对动物磁生物学研究的日益深入,基于实时荧光定量PCR (qRT-PCR)技术开展的磁响应基因转录表达谱研究有力促进了磁响应通路的鉴定和磁感受机制的揭示。【目的】 筛选近零磁场（near-zero magnetic field,NZMF）下短翅型灰飞虱（Laodelphax striatellus）稳定表达的内参基因,使对目的基因的定量分析更加准确。【方法】 迁飞性昆虫灰飞虱采自江苏省农业科学院试验田并在室内使用TN1三叶期稻苗进行扩繁（温度：（25.0±1.0）℃,相对湿度：70%—90%,光周期：14L﹕10D）。采用亥姆霍兹线圈室内模拟近零磁场（NZMF;＜500 nT）和地磁场（GMF;~50 000 nT）,人工模拟磁场强度有效处理空间为直径30 cm的球形空间,试验过程中严格控制除磁场强度外的环境因子（温度：（25.0±1.0）℃,相对湿度：75%,光周期：14L﹕10D）并利用磁通门计每日对人工模拟磁场进行校准和监测,灰飞虱连同TN1三叶期稻苗均置于试管中进行暴露处理,每隔两日与对照磁场中稻苗对调以避免稻苗潜在磁响应对灰飞虱的影响。利用Trizol法分别提取初羽化灰飞虱雌、雄成虫总RNA,检测各生物学重复RNA质量并调至含量一致,反转录为cDNA,利用qRT-PCR技术并结合常用内参筛选分析软件geNorm、NormFinder、BestKeeper以及在线综合分析系统RefFinder对在NZMF和GMF两种磁场强度下灰飞虱体内的内参基因稳定性进行评估筛选,其中,待评估的11个常用内参基因包括Actin1、Tubulin（α1TUB和α2TUB）、Elongation factor 1 alpha（EF-1α）、Glyceraldehyde-3-phosphate dehydrogenase（GAPDH）、Ubiquitin（UBI）、Ribosomal protein S11（RPS11）、Ribosomal protein S15e（RPS15）、Ribosomal protein L8（RPL8）、Ribosomal protein L9（RPL9）和ADP ribosylation factor2（ARF2）。【结果】 不同磁场环境（NZMF vs. GMF）下,灰飞虱短翅雌成虫EF-1α和RPL9表达稳定性在geNorm和NormFinder两种评估方法中都居于前两位,与BestKeeper软件的结果略有差异,进而利用在线工具RefFinder对以上3种方法的评估结果进行稳定性综合排序,结果表明EF-1α稳定性最好,RPL9稳定性次之;灰飞虱短翅雄成虫中,基于geNorm、NormFinder和BestKeeper 3种评估方法,α2TUB和RPL9表达稳定性中均居于前两位,而Actin1表达稳定性虽在NormFinder和BestKeeper中处于前两位,但其在geNorm中稳定性较低,最后,通过在线工具RefFinder综合分析表明,α2TUB稳定性最好,RPL9稳定性次之。【结论】 明确了不同磁场强度（NZMF vs. GMF）下适用于灰飞虱短翅雌、雄成虫中稳定表达的内参基因,其中,若使用双内参系统,雌成虫中可使用EF-1α和RPL9搭配,雄成虫中可使用α2TUB和RPL9搭配,为稳定表达的内参基因系统。此外,RPL9在灰飞虱短翅型雌、雄成虫中均可作为稳定的单一内参基因使用。研究结果确保了对灰飞虱响应磁场强度变化研究中关键目的基因转录表达的准确定量,并为今后开展磁场强度变化下的转录表达谱分析提供了有力保障。     

Insecticide resistance of the field populations of oriental armyworm,Mythimna separata (Walker) in Shaanxi and Shanxi provinces of China

Resistance of five field populations of Mythimna separata(Walker) collected from Shaanxi and Shanxi provinces of China to six different insecticides was evaluated by leaf dip method in the laboratory. The results showed that all populations were relatively sensitive to emamectin benzoate with a resistance ratio(RR) of 0.583–1.583 folds. All populations showed susceptible or low level resistance to chlorantraniliprole and beta-cypermethrin. Compared with a relatively susceptible strain of M. separata, the resistance level of the whole populations ranged from susceptible to moderate to chlorpyrifos and lambda-cyhalothrin, moderate to high to phoxim(RR=19.367–70.100) except for population from Sanyuan County(RR=2.567). Pair-wise correlation analysis among different insecticides indicated that chlorpyrifos has a significantly positive and significant correlation with emamectin benzoate. Chlorantraniliprole didn't have significant correlation with emamectin benzoate, chlorpyrifos and phoxim. Therefore, emamectin benzoate, chlorantraniliprole and beta-cypermethrin are recommended to control oriental armyworm. Meanwhile, to postpone the occurrence and development of insecticide resistance in Shaanxi and Shanxi provinces, alternative and rotational application of insecticides between chlorantraniliprole and emamectin benzoate or chlorpyrifos is necessary.     

Effects of constant and stage-specific-alternating temperature on the survival,development and reproduction of the oriental armyworm,Mythimna separata (Walker) (Lepidoptera: Noctuidae)

Migratory insects make diverse adaptive strategies in response to changes in external environment. Temperature has an impact on the survival, development, reproduction, and migration initiation of insects. Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention. Three constant temperature treatments(20, 25 and 30°C) and three pupal-alternating temperature treatments(20–25, 25–20 and 25–30°C) were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops. The 25°C treatment was considered optimal with 20 and 30°C as low suitable temperature and high temperatures, respectively. The survival rate was relatively low before third instar larvae at 20°C(63.0%) and 20–25°C(70.1%), and extreme low after pupal stage at 30°C(20.6%). Developmental duration of each stage was negatively correlated with temperature. The adult preoviposition period, when most migratory insects initiate migration, was the shortest at 25°C(2.69d) but was lengthened at both low suitable(7.48d for 20°C, 6.91d for 25–20°C and 4.57d for 20–25°C) and high temperatures(3.74d for 25–30°C and 5.00d for 30°C). Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature. The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.     

Motions of the Earth's Core and Mantle, and Variations of the Main Geomagnetic Field

Theoretical work on the magnetohydrodynamics of the earth's liquid core indicates (a) that horizontal variations in the properties of the core-mantle interface that would escape detection by modern seismological methods might nevertheless produce measurable geomagnetic effects; (b) that the rate of drift, relative to the earth's surface, of nonaxisymmetric features of the main geomagnetic field might be much faster than the average zonal speed of hydrodynamic motion of core material relative to the surrounding mantle; and (c) why magnetic astronomical bodies usually rotate. Among the consequences of (a) and (b) are the possibilities that (i) the shortest interval of time that can be resolved in paleomagnetic studies of the geocentric axial dipole component of the earth's magnetic field might be very much longer than the value often assumed by many paleomagnetic workers, (ii) reversals in sign of the geomagnetic dipole might be expected to show some degree of correlation with processes due to motions in the mantle (for example, tectonic activity, polar wandering), and (iii) variations in the length of the day that have hitherto been tentatively attributed to core motions may be due to some other cause.     

Effect of three insect-resistant maizes expressing Cry1Ie,Cry1Ab/Cry2Aj and Cry1Ab on the growth and development of armyworm Mythimna separata(Walker)

Three transgenic maize events(IE09 S034, Shuangkang 12–5 and C0030.3.5) produced Cry1 Ie, Cry1 Ab/Cry2 Aj and G10-EPSPS, Cry1 Ab and EPSPS, respectively, all of which target the Asian corn borer. The oriental armyworm Mythimna separata(Walker) is the secondary target. In this study, the effects of the three Bt maizes on the development and survival of armyworm were studied. The results showed that IE09 S034 had insecticidal activity against 1 st instar larvae, and the survival rate of armyworm fed with Bt maize for 10 days was 46.2%, significantly lower than that of the control. The larvae at 3 rd–6 th instar were more tolerant of the Bt toxin than the early instar larvae. However, Shuangkang 12-5 had good insecticidal activity against 1 st–5 th instar larvae. The mortality was nearly 100% when the larvae were fed with Shuangkang 12-5 before 3 rd instar, and the toxin had quick-acting efficacy. This event significantly inhibited the development of armyworm; that is, the larval duration of the 3 rd and 4 th instar larvae fed with Shuangkang 12-5 was prolonged by 4.5 and 3.0 days, respectively. The pupal weight and egg number were also significantly lower than those of the control. For C0030.3.5, it could control 1 st–5 th instar larvae effectively. The mortality rates were all over 50% if 1 st–3 rd larvae were fed with this event. The pupal weight of 4 th–6 th instar larvae fed with Bt maize were only 53.9, 56.8 and 54.6%, respectively, compared to that of the control. The number of eggs laid was significantly less than the control. The results indicate that all three transgenic maize events exhibit the potential to provide effective control of early instar larvae of armyworm, which can be commercialized in future to control lepidoptera pests such as Asian corn borer and armyworm.     

辛基酚对家蚕（Bombyx mori L.）生长发育的影响

为探讨辛基酚对鳞翅目模式昆虫家蚕生长发育的影响,使用添加0.01～0.08 g·kg~(-1)辛基酚(4-tert-octylphenol,4-t-OP)的人工饲料饲养家蚕(Bombyx mori L.),研究了4-t-OP对家蚕幼虫和蛹的生长发育速度、生长量、发育整齐度和生命力等影响。结果表明:连续取食0.01 g·kg~(-1)以上浓度4-t-OP的饲料,家蚕幼虫和蛹的生长发育速度(幼虫期和蛹期发育经过时间)、生长量(幼虫期体质量和蛹期茧层量)、生命力(3龄起蚕绝食生命时数、4龄起蚕结茧率、蚕茧的死笼率和羽化率)等都明显下降,抑制眠蚕体质量。4-t-OP对家蚕幼虫生长发育后期、化蛹及羽化等发育变态期的影响更加明显,其在家蚕体内可能有累积效应。添食0.08 g·kg~(-1)4-t-OP的家蚕不能完成生活史。研究表明,4-t-OP对家蚕生长发育毒性影响有显著的浓度效应和时间效应。     

西门岛人工秋茄林恢复对大型底栖生物的影响

选择乐清湾西门岛海域相同高程断面不同造林时间的人工红树林(秋茄林)、光滩和互花米草丛,采用空间代替时间的方法,分析我国分布最北界人工红树林造林过程对大型底栖生物的影响.大型底栖动物生活型分布基本表现为幼林(1、4、8a秋茄林)以底上附着型为主,而在光滩、50a秋茄林和互花米草中底下生活类群相对增加.并且穴居型动物只出现在发育成熟的生态系统内.各项指标显示50a老林群落生态稳定性较好,光滩和互花米草丛次之,但优于发育中的秋茄幼林.与以往研究结果不同,50a老林的大型底栖动物生物种类的丰度及群落的物种多样性最高,并不与红树林的发育状况呈负相关,也不比邻近光滩低.结合50a林下滩涂底泥情况,西门岛50a红树林林下滩涂的底质发育要落后于国内天然红树林土壤.这可能与当地红树林造林规模小以及强潮差海域有关.此外,红树林恢复过程中,大型底栖动物生物多样性与生态稳定性之间的线性关系,其适用的系统面积和演替时间的尺度范围有必要做更加深入的探讨.     

A flexible unmanned aerial vehicle for precision agriculture

An unmanned aerial vehicle (??VIPtero??) was assembled and tested with the aim of developing a flexible and powerful tool for site-specific vineyard management. The system comprised a six-rotor aerial platform capable of flying autonomously to a predetermined point in space, and of a pitch and roll compensated multi-spectral camera for vegetation canopy reflectance recording. Before the flight campaign, the camera accuracy was evaluated against high resolution ground-based measurements, made with a field spectrometer. Then, ??VIPtero?? performed the flight in an experimental vineyard in Central Italy, acquiring 63 multi-spectral images during 10?min of flight completed almost autonomously. Images were analysed and classified vigour maps were produced based on normalized difference vegetation index. The resulting vigour maps showed clearly crop heterogeneity conditions, in good agreement with ground-based observations. The system provided very promising results that encourage its development as a tool for precision agriculture application in small crops.     

磁场对花蛤抗氧化酶活性的影响

在实验室模拟磁场,观察暴露在100～135 mT磁场条件下20 d的花蛤肝胰腺及鳃中超氧阴离子自由基(O_2~-.)的产生速率、超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性、丙二醛(MDA)含量的变化。结果表明:在100～135 mT磁场强度下,花蛤腮和肝胰腺中的O_2~-.的产生速率增加;SOD活性、POD活性都呈现应激性上升;MDA的含量没有表现出太大的变化。100～135 mT强度的磁场对花蛤产生了氧化胁迫,但对膜结构尚未产生影响。     

高压生物静电场对雏鸡增重的影响

为研究高压生物静电场对肉蛋两用雏鸡生长发育状况的影响,采用不同强度的高压静电场和不同作用时间处理雏鸡,结果表明:施加的电场场强相对低时(+21.4 kV/m),无论作用时间长短,均未见统计学差异(P＞0.05);28日龄时,电场场强+35.7kV/m作用30 min/(次·日)较作用15 min/(次·日)的雏鸡体重增加显著(P＜0.01);电场场强±28.6 kV/m,作用30 min/(次·日),负电场高于正电场的作用效果,平均体重增长率分别为59.59％和23.46％;而电场场强增到±71.4 kV/m,作用效果明显降低.结果显示,适宜的电场强度和作用时间有促进雏鸡体重增加的作用,在一定范围内的不同场强和不同作用时间对雏鸡体重增加的影响有所差异.     

近零磁场下干扰磁响应关键基因对褐飞虱寿命的影响

【目的】 隐花色素（cryptochrome, Cry）和铁硫簇蛋白IscA（iron-sulfur cluster assembly,即MagR）是生物体内潜在的磁受体蛋白,本研究通过RNA干扰（RNAi）技术,分别敲减褐飞虱（Nilaparvata lugens）体内的磁响应关键基因NlCry1、NlCry2和NlMagR,旨在探明近零磁场（near-zero magnetic field,NZMF）环境下,以上3种基因在褐飞虱寿命调节过程中的作用,从而间接探讨这3种基因对磁场的响应情况。【方法】 采用RNAi技术,以实验室正常磁场环境下稳定饲养的短翅初羽化褐飞虱雌雄成虫为材料,通过向其体内注射双链RNA（dsRNA）分别抑制磁响应关键基因NlCry1、NlCry2和NlMagR,随后立即分别放入正常磁场（geomagnetic field,GMF）和近零磁场中,于每日相同时间观察记录试虫寿命。同时于注射后的1、2和3 d通过RNAiso Plus法提取GMF中褐飞虱雌成虫总RNA,反转录合成第一链DNA,后采用实时荧光定量PCR（RT-qPCR）技术检测该基因的表达情况,以确定基因干扰效率。【结果】 注射dsNlCry1后,褐飞虱雌雄成虫寿命在近零磁场和正常磁场间均无显著差异。注射dsNlCry2后,近零磁场中褐飞虱雌雄成虫寿命比正常磁场分别显著延长27.78%和50.04%;此外,与注射dsGFP处理相比,正常磁场下注射dsNlCry2的雌成虫寿命缩短,而近零磁场下注射dsNlCry2的雌成虫寿命延长,但二者差异均不显著;近零磁场和正常磁场下注射dsNlCry2的雄成虫寿命均缩短（25.41%和10.73%）,且正常磁场下差异显著。近零磁场中,注射dsNlMagR的雌成虫寿命较注射dsGFP的寿命显著缩短了16.48%,而雄成虫寿命在磁场间、干扰处理间的差异均不显著。【结论】 磁场变化下褐飞虱雌雄成虫体内3种磁响应关键基因对其寿命的调节功能存在差异。其中,NlCry2对磁场变化存在敏感响应,表现为敲减该基因与磁场变化的互作显著地影响雌雄成虫寿命,且表现出“性二型性”;NlMagR也可对磁场变化产生明显响应,但该响应只存在于雌成虫;此外,NlCry1对磁场变化无响应,该基因或与褐飞虱雌雄成虫寿命调节无关。     

Evaluation of Chinese rice varieties resistant to the root-knot nematode Meloidogyne graminicola

The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of Oryza sativa(aus, hybrid aus, indica, hybrid indica, temperate japonica, tropical japonica). Nematode development in highly resistant varieties was also evaluated. Analyses of randomly selected 35 varieties showed the number of M. graminicola nematodes inside the roots correlated very strongly(r=0.87, P≤0.05) with the nematode gall index, and the results from pot and field experiments revealed similar rankings of the varieties for resistance/susceptibility. Among the 136 tested varieties, temperate japonica displayed the highest gall index, followed by tropical japonica, indica, hybrid indica, aus, and hybrid aus. Zhonghua 11(aus), Shenliangyou 1(hybrid aus) and Cliangyou 4418(hybrid indica) were highly resistant to M. graminicola under both pot and field conditions. Further examination of nematode development suggested that compared to susceptible rice, M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into females. The promising varieties found in the present research might be useful for the breeding of hybrid rice in China and for the further development of practical nematode management measures.