首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The high-altitude windborne transport of the second-generation moths of Helicoverpa armigera (Hübner) was observed with radar in July 2001 and 2002 at Langfang, Hebei province, China. Moths of local populations took off at dusk, with area density peaking ca. 0.5 h later. The variation of area density through the night suggested that the maximum flight duration was about 8.5 h. The moths generally ascended to altitudes of up to 1500 m above ground level (AGL) and formed layer concentrations at ca. 300, 500, and 1000 m AGL. Multiple layering was very common and layers were located at zones of maxima in wind speed or in wind shear rather than in temperature inversions. Both the displacement direction and the orientation of the insect were at an acute angle to the downwind direction, rather than being distributed at random, and varied as the wind direction changed. The windborne moths were mainly transported into northeastern China where maize at the silking stage would have provided good hosts for the subsequent (third) generation of H. armigera. These population movements may account for the nondevelopment of resistance to Bt cotton in H. armigera in northern China.  相似文献   

2.
孙雅杰  陈瑞鹿 《昆虫知识》1997,34(4):201-203
以包覆细铜纱网的乒乓球作为标准检测目标,检测了X-频带,波长3cm的公主岭昆虫雷达观测空中飞行昆虫的有效距离。检测到乒乓球回波的最远距离为5185.6m;计算观测个体粘虫Mythimnaseparata(Walker)的最远有效距离约为2000m,观测个体褐飞虱Nilaparvatalugens(Stal)的最远有效距离的为300m。该雷达适于观测粘虫等体重几十mg的昆虫在空中的飞行动态。  相似文献   

3.
The wing loading of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), was found to decrease slightly with increasing size over a wide range of individual sizes and independent of sex. This makes it possible to use tags of the same weight for beetles of all sizes and suggests that if the addition of light electronic tags has any effect on the beetle's flight it will be similar across beetle size. The wing loading of individual potato beetles ranged from an average minimum 10.9 N m–2 to an average maximum of 15.6 N m–2 as their weights fluctuated over time following water and food uptake or dispersal. However, tests carried out in flight chambers indicate that beetles become incapable of upward flight as they go beyond an average wing loading of 11.8 N m–2, that is 101 N (10.3 mg) beyond their minimum weight. It is estimated from our results that electronic tags should weigh no more than 23–33% of the potato beetle's acceptable extra loading for the technique to have no or minimal impact on the number and quality of upward flights taken.  相似文献   

4.
ermák  Jan  Hru ka  Jiri  Martinková  Milena  Prax  Alois 《Plant and Soil》2000,219(1-2):103-116
Root systems of two mature Field maple trees (Acer campestre L.) growing in both shaded and non-shaded sites, on clay soil in an urban environment, were analyzed by ground penetrating radar (GPR), light microscope and sap flow techniques. The ground surface above the root systems was covered by asphalt. However, a small piece of garden existed near the non-shaded tree, and root area of roots growing in this direction increased significantly, due to a presumed increase in available water and nutrients. However, no garden was present near the shaded tree, therefore roots remaining under the asphalt surface did not increase in area in any particular direction. Maximum rooting depth of shaded and exposed trees, as determined by GPR, was approximately 1.4 and 1.7 m, respectively. The trees utilized relatively large amounts of water for transpiration, i.e. 65–140 l per fine summer day and in average 10 m3 per growing season. However, transpiration expressed per root surface area (and/or whole root system enveloping area) was practically the same in both trees, i.e. 1 dm3 m-2 d-1 or almost 100 dm3 m-2 per growing season. These figures represented about 50% of potential evapotranspiration when considering projected crown areas. Increased transpiration under long-term high evaporation demands may cause occasional local drying of soil around roots, associated with soil shrinking in clay, which can be followed by serious damage to buildings.  相似文献   

5.
Large parts of the continents are continuously scanned by terrestrial weather radars to monitor precipitation and wind conditions. These systems also monitor the mass movements of bird, bat, and insect migration, but it is still unknown how many of these systems perform with regard to detection and quantification of migration intensities of the different groups. In this study that was undertaken within five regions across Europe and the Middle East we examined to what extent bird migration intensities derived from different weather radars are comparable between each other and relate to intensities measured by local small‐scaled radars, some of them specifically developed to monitor birds. Good correspondence was found for the relative day‐to‐day pattern in migration intensities among most radar systems that were compared. Absolute intensities varied between different systems and regions. The findings of this study can be used to infer about absolute bird migration intensities measured by different radar systems and consequently help resolving methodological issues regarding the estimation of migrant numbers in the Western‐Palearctic region. It further depicts a scientific basis for the future monitoring of migratory bird populations across a large spatio‐temporal scale, predicting their movements and studying its consequences on ecological systems and human lives.  相似文献   

6.
垂直监测昆虫雷达研究进展   总被引:2,自引:0,他引:2  
昆虫雷达可以远距离、 大范围、 快速地探测迁飞昆虫, 这极大促进了人类对昆虫迁飞行为的认识。垂直监测昆虫雷达技术是从20世纪70年代发展起来的一种监测高空迁飞昆虫种群的新工具。与传统的扫描雷达相比, 垂直监测昆虫雷达可以获得目标的位移速度、 位移方向、 定向、 体型大小和形状等参数, 因此, 对目标的识别能力更为精确。此外, 垂直监测昆虫雷达实现了在微机控制下的自动运行, 这使得应用昆虫雷达开展迁飞昆虫的日常监测成为可能。本文综述了垂直监测昆虫雷达的发展和应用, 介绍了设计原理和回波参数的解算方法, 讨论了其存在的不足及改进方案, 最后并对其在未来昆虫雷达网络建设中的应用进行了展望。  相似文献   

7.
Abstract. The biology of Paryphanta busbyi watti , an endangered carnivorous land snail, was studied mostly by following large juvenile and adult snails with harmonic radar. The snails are nocturnally active and most (79%) hide during the day under leaf litter or in dense vegetation. Fecal analysis showed that the diet is primarily earthworms, but some cannibalism of smaller snails occurs. Empty shells appear to be an additional source of dietary calcium. Mating occurred most frequently between April and July. Mating snails stayed together for 4–7 days, and each pair reversed their positions at least twice. Four snails were first found mating 151–1240 d after they acquired adult shells, and 7 snails were observed mating a second time after 66–298 d. We found 8 nests and observed 6 snails ovipositing; 5 snails laid eggs in holes they dug and one laid eggs in a crevice between rocks. In 2 instances, oviposition was recorded 52 and 140 d after mating. Snails were estimated to lay on average ∼17.5 eggs per year in 3–5 clutches. Most oviposition was observed in August/September, but some occurred between November and February. Of the snails that died, pigs killed 13.6% and humans inadvertently killed another 13.6%. Other snails died from unknown causes mostly during the drier and warmer months, from November to April. This large land snail survives in the presence of introduced predators, but some life history traits could predispose it to a rapid decline in numbers if new predators arrive.  相似文献   

8.
追踪天使——雷达昆虫学30年   总被引:20,自引:3,他引:20  
翟保平 《昆虫学报》1999,42(3):315-326
雷达昆虫学是一门新的学科分支。从它诞生起的30年来,英、美、澳、中四国的观测研究已初步阐明了昆虫在迁飞过程中的成层、定向、集聚等行为现象及其时空分布,揭示了大气结构和运动对昆虫迁飞的影响,为深化人们对昆虫迁飞行为机制的认识提供了许多令人耳目一新的画面;昆虫雷达技术也逐渐从研究走向实用,已经实现了对迁飞性害虫的长期、自动和实时监测。在全国建立VLR网并与GIS相结合,可望实现对我国重大虫灾的及时预警。  相似文献   

9.
The long-range, pheromone-mediated, flight behaviour of male moths under natural and mating disruption conditions was monitored by means of harmonic radar. Individual male turnip moths, Agrotis segetum (Denis & Schiffermüller) (Lepidoptera: Noctuidae), tagged with radar transponders, were released and tracked in plots with or without disruptive doses of sex pheromone. In addition, male attraction to pheromone-baited traps and mating of calling females in treated and untreated plots was investigated. High doses of a four-component pheromone blend reduced trap catch by 79% and mating of females by 62% when compared with control plots in pre-radar experiments. Surprisingly, this effect was not associated with any pronounced differences in flight behaviour of males between a treatment and a control plot as revealed by harmonic radar recordings. In total, 20 flight tracks from a control plot and 22 flight tracks from a treatment plot were analysed. Moths could be followed for up to 77 min, corresponding to a track length of 7350 m. Mean ground speed ranged from 0.7 m s–1 to 5.4 m s–1. There was a strong trend (P = 0.06) for a greater number of male orientations to traps from downwind in the control field compared to the treatment field. Many flight tracks were fragmented due to radar shadow. Advantages and constraints using harmonic radar to study the pheromone-mediated flight behaviour of nocturnal moths are discussed.  相似文献   

10.
Although radar has been used in studies of bird migration for 60 years, there is still no network in Europe for comprehensive monitoring of bird migration. Europe has a dense network of military air surveillance radars but most systems are not directly suitable for reliable bird monitoring. Since the early 1990s, Doppler radars and wind profilers have been introduced in meteorology to measure wind. These wind measurements are known to be contaminated with insect and bird echoes. The aim of the present research is to assess how bird migration information can be deduced from meteorological Doppler radar output. We compare the observations on migrating birds using a dedicated X‐band bird radar with those using a C‐band Doppler weather radar. The observations were collected in the Netherlands, from 1 March to 22 May 2003. In this period, the bird radar showed that densities of more than one bird per km3 are present in 20% of all measurements. Among these measurements, the weather radar correctly recognized 86% of the cases when birds were present; in 38% of the cases with no birds detected by the bird radar, the weather radar claimed bird presence (false positive). The comparison showed that in this study reliable altitudinal density profiles of birds cannot be obtained from the weather radar. However, when integrated over altitude, weather radar reflectivity is correlated with bird radar density. Moreover, bird flight speeds from both radars show good agreement in 78% of cases, and flight direction in 73% of cases. The usefulness of the existing network of weather radars for deducing information on bird migration offers a great opportunity for a European‐wide monitoring network of bird migration.  相似文献   

11.
人脑源性神经营养因子cDNA在COS7细胞中的表达及活性研究   总被引:4,自引:0,他引:4  
本文从质粒M13mp18-hBDNF中酶切回收人脑源性神经营养因子(hBDNF)全长基因,构建真核表达载体pCMV4-hBDNF。利用脂质体的方法转染COS7细胞,对转染后的COS7细胞提取RNA进行狭缝杂交分析和免疫细胞化学反应,分别从转录及翻译水平上检测BDNF基因在COS7细胞中的表达。实验还证实在COS7细胞中表达的hBDNF蛋白可分泌至胞外并可促进中脑黑质细胞的发育和生长,具有良好的生物学活性。  相似文献   

12.
Monochamus alternatus (Hope) is a severe wood‐boring pest in coniferous forests and a major vector of pine wilt disease in East Asia. Harmonic radar is a powerful tool for studying the dispersal behavior of insects and it could be applied to control pine wilt disease. In this study, we validated the application of harmonic radar for analyzing the dispersal behavior of M. alternatus beetles in a field environment. We determined the wing capacities of the beetles and the effects of electronic tagging and marking on their movement, flight ability, survivorship, and food consumption in the laboratory to confirm the suitability of this technique. The detection rate and recovery rate for beetles were analyzed separately using radar on caged pine stands and in the field environment. The results showed that the minimum wing capacity of the Japanese pine sawyer was 24.9 mg, which was seven times the weight of the electronic tag (3.5 mg). Marking and tagging the beetles had no significant adverse effects on their movement, flight capacity, food consumption, and survivorship. The detection rate using the radar system and recovery rate based on visual observations of the beetles in caged pines were both 95.6%. However, in the field environment, the detection and recovery rates were only 55.6% and 37.8% after one week, respectively, and 33.3% and 7.8% after two weeks. Harmonic radar is a promising technique for studying the dispersal behavior of the Japanese pine sawyer, but its performance is not satisfactory and major improvements are required for both the radar system and electronic tags.  相似文献   

13.
Weather surveillance radars are increasingly used for monitoring the movements and abundances of animals in the airspace. However, analysis of weather radar data remains a specialised task that can be technically challenging. Major hurdles are the difficulty of accessing and visualising radar data on a software platform familiar to ecologists and biologists, processing the low‐level data into products that are biologically meaningful, and summarizing these results in standardized measures. To overcome these hurdles, we developed the open source R package bioRad, which provides a toolbox for accessing, visualizing and analyzing weather radar data for biological studies. It provides functionality to access low‐level radar data, process these data into meaningful biological information on animal speeds and directions at different altitudes in the atmosphere, visualize these biological extractions, and calculate further summary statistics. The package aims to standardize methods for extracting and reporting biological signals from weather radars. Here we describe a roadmap for analyzing weather radar data using bioRad. We also define weather radar equivalents for familiar measures used in the field of migration ecology, such as migration traffic rates, and recommend several good practices for reporting these measures. The bioRad package integrates with low‐level data from both the European radar network (OPERA) and the radar network of the United States (NEXRAD). bioRad aims to make weather radar studies in ecology easier and more reproducible, allowing for better inter‐comparability of studies.  相似文献   

14.
An international and interdisciplinary Radar Aeroecology Workshop was held at the National Weather Center on 5-6 March 2012 on the University of Oklahoma campus in Norman, OK, USA. The workshop brought together biologists, meteorologists, radar engineers and computer scientists from 22 institutions and four countries. A central motivation behind the Radar Aeroecology Workshop was to foster better communication and cross-disciplinary collaboration among a diverse spectrum of researchers, and promote a better understanding of the ecology of animals that move within and use the Earth's lower atmosphere (aerosphere).  相似文献   

15.
Quantitative radar studies are an important component of studying the movements of birds. Whether a bird, at a certain distance from the radar, is detected or not depends on its size. The volume monitored by the radar is therefore different for birds of different sizes. Consequently, an accurate quantification of bird movements recorded by small‐scale radar requires an accurate determination of the monitored volume for the objects in question, although this has tended to be ignored. Here, we demonstrate the importance of sensitivity settings for echo detection on the estimated movement intensities of birds of different sizes. The amount of energy reflected from a bird and detected by the radar receiver (echo power) depends not only on the bird's size and on the distance from the radar antenna, but also on the beam shape and the bird's position within this beam. We propose a method to estimate the size of a bird based on the wingbeat frequency, retrieved from the echo‐signal, independent of the absolute echo power. The estimated bird‐size allows calculation of size‐specific monitored volumes, allowing accurate quantification of movement intensities. We further investigate the importance of applying size‐specific monitored volumes to quantify avian movements instead of using echo counts. We also highlight the importance of accounting for size‐specific monitored volume of small scale radar systems, and the necessity of reporting technical information on radar parameters. Applying this framework will increase the quality and validity of quantitative radar monitoring.  相似文献   

16.
华北地区昆虫秋季迁飞的雷达观测   总被引:14,自引:0,他引:14  
吴孔明  程登发  徐广  翟保平  郭予元 《生态学报》2001,21(11):1833-1838
1999年9-10月利用昆虫雷达对华北地区昆虫秋季回迁的观测表明,秋季迁飞主要发生于19:00-05:00时,飞行高度一般在300-2000m。迁飞方向与风向一致,多为从东北向西南方向迁飞。运行速度和飞行高度成正相关,迁飞个体的平均运行速度由392m高度的4.8m/s增加到2000m处的27.8m/s。空中灯光诱捕表明,甜菜夜蛾和棉铃虫为优势迁飞种类。  相似文献   

17.
Systematic significance of mature embryo of bamboos   总被引:1,自引:0,他引:1  
The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.  相似文献   

18.
Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.  相似文献   

19.
Radar observations of moths migrating in a nocturnal low-level jet   总被引:3,自引:0,他引:3  
Abstract. 1. Radar observations of insects migrating at night over central-western New South Wales have detected an instance of migration in a low-level wind jet.
2. From the characteristics of the radar echoes, and from the catches obtained in traps at ground level and at the altitude of migration, the migrants can be identified as noctuid and pyralid moths of a number of different species.
3. The migration, which was in a downwind direction, started at dusk and ended at about dawn. During the period immediately before first light, a large proportion of the migrants were concentrated into a 100m deep layer at an altitude of about 250m; this layer had not been present during the first half of the night.
4. The boundary layer wind profile at dawn exhibited a clear low-level jet structure, with a wind maximum between 100 and 300m, and strong shear in the wind direction below 300m. A strong surface temperature inversion, but not a wind-speed maximum, had been present the previous evening.
5. The formation of the layer concentration in the upper part of the jet may be accounted for in terms of previously described responses of nocturnally migrating insects to a surface temperature inversion. It is not therefore necessary to assume that the migrants were responding specifically to the presence of a wind-speed maximum.  相似文献   

20.
The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号