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61.
稻苞虫卵空间格局参数特征及其应用   总被引:3,自引:0,他引:3  
近年来,稻苞虫已成为川西北稻区仅次子螟虫的严重害虫.为对其生物学特性的进一步了解,1978—1983年对猖獗世代(第三代)卵在稻田空间格局进行了研究,结果表明稻苞虫卵在稻田呈负二项分布;格局的结构是以疏松的个体群形式存在;个体群间是聚集的,个体群内的卵粒是随机的.利用空间格局参数Mk、α、β值,估计了个体群的大小和与平均密度的关系;分析了卵在稻田聚集的原因;探讨了平均卵密度与k值的关系.依:(x-)=K(P-1/k0-1)关系由未着卵频率(P0)来估计卵密度.给出了以零频率估计卵密度和以概率保证的理论抽样数方法的结合,来实现有效的简易抽样.同时以未着卵丛率来检定田间发生程度和以卵量来检定是否达到现行防治阈限的序贯抽样检索.  相似文献   
62.
Putative virulence factors of Botrytis cinerea acting as a wound pathogen   总被引:4,自引:0,他引:4  
Abstract The grey mold fungus, Botrytis cinerea , is a wound pathogen of worldwide distribution, and causes rots of almost all fruits and vegetables. The fungus can also penetrate directly from appressoria to cause severe losses to growers of flowers. B. cinerea secretes a number of inducible attack enzymes which can degrade host cell walls to widen the infection, including β-glucosidase, pectin methylesterase, the polygalacturonases, and aspartate proteinase; laccase and benzyl alcohol oxidase appear to have roles of detoxifying compounds derived from the host during pathogenesis, a function that we believe enhances the virulence of the pathogen. With additional research, several oxidases may also become a part of the virulence group. Much more work is needed, in particular the analysis of mutants, to assign formally the roles suggested here.  相似文献   
63.
选用含油量、油脂成分、结实性状、分布范围和繁殖性状作为评价指标,运用灰色关联度分析法对云南分布的、可作为生物柴油原料的188种主要木本油料植物(含油量≥30%)进行了综合评价。结果表明:滇新樟(Neocinnamomum caudatum)、西南红山茶(Camellia pitardii)等29种木本油料植物与理想种的关联度均超过0.6500,具有良好的综合性状,可以在研究开发的基础上作为云南生物柴油产业的原料植物来推广应用。此外,脉叶虎皮楠(Daphniphyllum paxianum)、牛紏吴萸(Evodia trichotoma)、长梗大花漆(Toxicodendron grangiflorum var. longipes)是这次新发现的3种具有开发潜力的木本生物柴油原料植物。  相似文献   
64.
草炭作为土壤改良剂,可有效调节土壤基质的理化性质.本研究利用草炭在盆栽条件下改良葡萄根际土壤理化性质,用Logistic方程对葡萄年生长节律进行了模拟,并用灰色关联法分析了草炭含量、土壤物理性状及葡萄生长相互关系.结果表明:增施草炭可以显著提高土壤孔隙度、粘粒性物理含量;不同土壤栽培条件下葡萄生长均可用Logistic函数曲线进行可靠描述(R~20.98),并用数学分析的方法确定不同处理梢蔓和梢蔓粗的速生期和速生点,将一年生葡萄生长分为生长前期、速生期和生长后期;土壤施加草炭后,缓苗期缩短,盆栽葡萄较快进入快速生长期,使生长前期缩短4-7d;灰色关联度分析表明,土壤物理性粘粒含量、孔隙度对葡萄新梢生长影响最大,比重对其影响不显著.  相似文献   
65.
计算机灰度法对牙槽骨密度变化的初步评价   总被引:2,自引:0,他引:2       下载免费PDF全文
本论文使用灰度法在数字化曲面体层片上比较牙周炎治疗前与基础治疗后2个月牙槽骨密度的变化情况,初步评价了计算机灰度法对牙槽骨密度变化检测的敏感性。研究结果表明,灰度法提示基础治疗后2个月牙槽骨密度显著增加(P=0.003),揭示了计算机灰度法对评价牙槽骨密度改变具有较高的灵敏度。  相似文献   
66.
Capsule Avian predators are principally responsible.

Aims To document the fate of Spotted Flycatcher nests and to identify the species responsible for nest predation.

Methods During 2005–06, purpose-built, remote, digital nest-cameras were deployed at 65 out of 141 Spotted Flycatcher nests monitored in two study areas, one in south Devon and the second on the border of Bedfordshire and Cambridgeshire.

Results Of the 141 nests monitored, 90 were successful (non-camera nests, 49 out of 76 successful, camera nests, 41 out of 65). Fate was determined for 63 of the 65 nests monitored by camera, with 20 predation events documented, all of which occurred during daylight hours. Avian predators carried out 17 of the 20 predations, with the principal nest predator identified as Eurasian Jay Garrulus glandarius. The only mammal recorded predating nests was the Domestic Cat Felis catus, the study therefore providing no evidence that Grey Squirrels Sciurus carolinensis are an important predator of Spotted Flycatcher nests. There was no evidence of differences in nest survival rates at nests with and without cameras. Nest remains following predation events gave little clue as to the identity of the predator species responsible.

Conclusions Nest-cameras can be useful tools in the identification of nest predators, and may be deployed with no subsequent effect on nest survival. The majority of predation of Spotted Flycatcher nests in this study was by avian predators, principally the Jay. There was little evidence of predation by mammalian predators. Identification of specific nest predators enhances studies of breeding productivity and predation risk.  相似文献   
67.
ABSTRACT

This study compared the vocalization of two sympatrically occurring species of hamster: the Eversmann hamster Allocricetulus eversmann and the Grey hamster Cricetulus migratorius. The animals were tested in conspecific pairs for 5 min. Because of the high level of aggressiveness of both species, the hamsters were separated by a mesh partition, but they had olfactory, visual and acoustic contact. Female and male Eversmann hamsters vocalized more than those of Grey hamsters. This was expressed by emission of low-frequency calls as well as by ultrasounds. The difference in vocalization between the two species was also reflected in the basic structure of ultrasonic vocalizations. Grey hamster high-frequency (ultrasonic) pulses were longer and had larger bandwidths and lower minimum frequencies than Eversmann hamster calls. Within-species comparison of vocalization indicated that males of both species emitted fewer ultrasounds than females did. These differences could have an important role in communication within and between species living in the same area and preferring the same habitats.  相似文献   
68.
C. BUDDE 《Bioacoustics.》2013,22(2-3):161-173
ABSTRACT

The study describes the vocal repertoire of the Grey Crowned Crane Balearica regulorum gibbericeps and speculates on the purpose the calls serve. The repertoire consists of 4 tonal and 7 non-harmonic calls. Chicks have 3 different vocalizations.  相似文献   
69.
We give a mini-review of existing European risk assessment procedures and present a newly developed and tested risk assessment tool for invasive alien species (IAS) in Germany and Austria, the “German–Austrian Black List Information System” (GABLIS). Based on the analysis of existing European national risk assessment systems, we analyse and discuss: the assessment criteria used; which impacts of IAS (biodiversity, economy) have been considered; for which taxonomic groups has the assessment been designed and tested; how many and which list categories have been used; and, the status of the assessment, i.e. legally binding or advisory. We found that the application of risk assessment systems in Europe started belatedly, however recently a considerable number of assessment systems have been developed and tested. These systems encompass a wide range of purposes and approaches, and so far, no common standard on the aspects mentioned above has been emerged.GABLIS has been developed as a trans-national and taxonomically universal risk assessment system, which takes into account solely the detrimental effects of alien species on biodiversity. We describe which kinds of impacts are considered and how the thresholds have been scaled. We present the structure of the list categories, and we discuss the necessary underlying data for assessment, the assessment criteria and their scaling, and the assessment procedure. Five basic and six complementary criteria are used to assess the alien species’ impact. GABLIS includes three main list categories (White List, Grey List, and Black List).We discuss the practicability of GABLIS by presenting the assessment results of a model taxon (fish), and by presenting the assessment protocol for a vascular plant species. We discuss the necessary data quality for assessments, and the factors which account for differences in the assessments between both countries. We also report on experiences gained in assessments (e.g., average time necessary for assessments). The lessons learnt are discussed in the national and European political context of IAS management.Finally, we explore the strengths and caveats of this approach in the context of national policy on IAS in Germany and Austria and the ongoing European political initiatives. GABLIS is intended to serve as a comprehensive, flexible, but robust risk assessment tool for Central Europe. Being a trans-national risk assessment tool, GABLIS also tests principles, which might contribute valuable insights for a future overall strategy against IAS in Europe.  相似文献   
70.
Prey impaling in shrikes Laniidae is considered to be a feeding adaptation to dismember and consume large prey and is unique among food-storing animals. However, other exaptations of this behaviour were recorded, including signals in mate choice, where cache size is a sign of male quality. Thus, due to a strong sexual selection, male and female birds might differ in their behavioural patterns of impaling behaviour. We examined sex differences in impaling behaviour of the Great Grey Shrike Lanius excubitor - one of the species where caches are known to be sexual signals. Data were collected in western Poland during breeding seasons in the years 2006-2010. In the studied population, we recorded several sex-specific differences in impaling behaviour. Males impaled prey, invertebrates as well as vertebrates, faster and with fewer attempts per impaling event than females. Sexes differed in the location of impaled prey; males selected more visible places, especially during the mating and courtship phase, whereas females impaled prey in concealed locations. Males also had slightly better impaling success compared to females. We suggest that sex differences in impaling behaviour may be due to different uses of impaled prey, and the better impaling skills of males may be the result of better experience in impaling which is forced by sexual selection in this species. We also discuss other factors which might trigger sex-specific differences in food caching by shrikes.  相似文献   
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