社会资本与年轻牧民草地租赁行为

由于没有赶上草场承包,加上非牧就业的困难,占总牧户数近四分之一的年轻牧户将租赁作为获取土地维持生计的重要途径。然而,与年长牧民相比,年轻牧民面临更高租赁价格从而更难于租到土地。文中采用内蒙古呼伦贝尔和锡林郭勒12个纯牧业旗422个牧户的实地调研数据,运用计量分析方法,探讨了社会资本对年轻牧民租赁草地的影响。研究发现,社会资本能显著提高整体牧户的草地租赁,但对年轻牧户的影响要显著弱于年长牧户。社会资本的代际差异是导致这一结果的主要原因。鼓励年轻牧户更多参与社区事务、获取信息和赢得信任,从而降低草地租赁门槛成为年轻牧民获取生计途径、促进牧业可持续发展和牧区社会和谐稳定的关键。     

基于环境规制视角下牧户风险感知对亲环境行为的影响研究——以三江源地区为例

牧户亲环境行为是实现三江源地区生态经济社会可持续发展的根本保证。文中以三江源地区牧户为调研对象,使用多元有序Logistic模型,实证分析牧户风险感知对亲环境行为的影响,同时引入环境规制作为调节变量,探究环境规制在牧户风险感知与亲环境行为关系中的调节效应。研究表明：1)牧户风险感知对亲环境行为有显著的正向影响,其中,环境风险感知对亲环境行为的影响更加显著。2)环境规制对牧户风险感知与亲环境行为之间的关系起到正向调节作用,且约束型、引导型和激励型规制均能正向调节牧户风险感知与亲环境行为之间的关系。据此,文中从提升风险感知水平和健全环境规制制度两方面提出对策建议。     

牧户生计资本对其草原畜牧兼业化的影响研究——以四川省红原县和若尔盖县为例

从牧民生计视角看,草原生态保护的关键在于提升牧民的兼业化能力,减少牧民对草原畜牧业收入的依赖,降低对天然草原资源的消耗.本文基于四川省红原县、若尔盖县651份实地调研数据,运用排序选择模型进行回归分析,研究了牧户生计资本对其畜牧兼业化的影响.研究表明:人均住房面积、草补收入、家庭总收入对牧民的草原畜牧兼业化有正向影响;...     

草原生态补奖政策对牧户生计脆弱性的影响——来自青海省河南蒙古自治县牧户的经验分析

草原生态补奖政策自实施以来，对我国牧户生产生活形成重要影响。作为面向牧户生计最重要的政策之一，科学评价现有草原生态补奖政策对牧户生计脆弱性的影响，并探究如何实现草原生态补奖政策与牧户生计脆弱性之间的良性发展，具有必要性和现实意义。文中基于OLS模型，使用青海省河南蒙古自治县304户牧户的微观调研数据，以综合测度牧户生计脆弱性指数为基础，实证检验了草原生态补奖政策对牧户生计脆弱性的影响，并运用分位数回归模型和渠道效应模型进一步探究这一影响的异质性与作用机制。研究发现：1)草原生态补奖政策对牧户生计脆弱性存在显著正向影响。2)草原生态补奖政策对不同生计脆弱性牧户的影响存在一定的异质性，草原生态补奖政策主要对低生计脆弱性牧户有显著的影响，而对中高脆弱性牧户影响不显著。3)渠道效应机制分析表明，生态冲击性、收入多样性和可持续动能在草原生态补奖政策与牧户生计脆弱性之间发挥着重要作用。因此，未来有必要通过降低牧户生态冲击性、提升收入多样性和增强牧户可持续动能推动草原生态补奖政策实施，并针对不同群体采取差别化的草原生态补奖政策，进行促进草原生态补奖政策效应的发挥。     

新疆参与旅游业牧民生计资本研究——以喀纳斯和乌鲁木齐县南山生态旅游区为例

农牧民生计资本是可持续生计研究框架的基础,决定了农牧民家庭生计策略的选择与结果。文中运用问卷调查与入户访谈相结合的方法,开展了新疆生态旅游发展典型区域内参与旅游业牧民生计资本的实证研究。通过采用计算赋值与标准化的数据预处理方法,借助社会统计软件工具,对样本牧民的生计资本水平进行了比较研究。结果发现样本生计资本总值仅为0.249,处于较低水平状态,其中物质资本水平最低,人力资本水平最高;不同生计资本水平的牧民分布很不均衡,自然资本和物质资本在0.2以下水平的牧民累积百分比分别为52.7%和79.1%;牧民家庭特征中家庭人口数最多的牧户生计资本总值最低,民族及调查区域的生计资本水平差异不大。     

草原补奖是否促进了牧户增收与收入多样化?——基于青海省微观调研数据

草原补奖政策兼具恢复草原生态环境与促进牧民增收双重目标。文中以青海省共和县牧户微观调研数据为基础，应用多元线性回归模型和多元有序Logit模型，评估草原补奖政策参与对牧户收入水平与结构的影响及其异质性。研究结果表明：草原补奖有效促进了牧户增收，且该促进作用随着牧户收入水平的提高而增强；补奖政策参与反而抑制了牧户收入来源多样化，拥有较大承包草地面积的牧户获得更多的补奖，继而将其用于扩大畜牧业生产，降低了牧户选择多样化生计策略的积极性，与该补偿政策实施初衷相悖。     

促进抑或阻碍：草原生态补奖如何影响牧户草地租赁倾向?

草地经营权流转是提高草地资源配置效率、实现草原畜牧业规模化产业化的主要途径。草原生态保护补助奖励政策(以下简称“草原补奖政策”)是恢复草原生态、促进牧民增收的重要手段。在国家大规模推进草原补奖政策的背景下,其是否影响牧户草地租赁行为是尚待解决的关键科学问题。文中基于青海省共和县和同德县599份牧户调研数据,实证检验了草原补奖对牧户草地租赁倾向的影响、作用机制与异质性。研究发现：一次型草原补奖与草地资源投入存在互补效应,对牧户草地租入倾向起到了促进作用;连续型草原补促进了牧业劳动力转移,提升了牧户草地租出倾向。机制分析表明,一次型补奖通过激励采纳舍饲养殖、增加贷款间接促进牧户租入草地;连续型补奖通过提升非牧就业间接促进牧户租出草地。以上结论总体上在纯牧区、老年户主家庭表现更为显著。因此,在今后的草原补奖政策可以因地制宜实施差异化补偿标准,同时结合就业、金融等措施进一步促进草地租赁市场的发展。     

草原确权是否提高了牧民产权安全认知?——基于不同类型牧户的异质性分析

草原确权作为稳定草原产权的正式制度安排,对激励牧民生产性投资、促进草地流转,实现草原可持续利用具有重要意义.牧民的产权认知受当前确权环境和以往产权经历的影响而不同,文章采用多分类有序Logit模型,探究基于不同类型牧户异质性视角下的草原确权对牧民产权安全认知的影响.结果 表明:1)区域内,已完成草原确权颁证的牧户占87...     

牧民草地生态保护认知与行为的实证分析——基于西藏75个自然村的实证分析

依据拉萨、那曲及林芝地区牧民入户调查资料,对西藏牧民草地退化的认知及其放牧行为进行深入分析,揭示牧民草地资源保护诉求与草地资源利用倾向。分析结果表明:牧民对草地资源退化已经形成共识;牧民具有草地保护认知,但草地退化原因大多归因于政府保护不力,较少考虑养殖规模的影响;面对日益恶化的草地资源,牧民仍有扩大养殖规模趋势。     

生计资本对牧民减畜意愿的影响分析—基于内蒙古372户牧民的微观实证

基于内蒙古372户牧民的抽样调查数据,采用熵值法评估了牧民生计资本状况,随后检验了生计资本对牧民减畜意愿的影响。结果表明:1)牧民生计主要依靠人力资本和金融资本,其次是社会资本和物质资本,最后是自然资本。2)生计资本中社会资本、物质资本、人力资本和金融资本能显著促进牧民减畜意愿,自然资本则反之。其中,社会资本中的社会网络和参与集体活动情况、物质资本中的牲畜数量、人力资本中的劳动力数量、金融资本中的家庭现金收入均能显著促进牧民减畜意愿,自然资本中的草场面积和草地质量能显著抑制牧民减畜意愿。     

Dermestid beetles in ‘evolution Canyon’, lower Nahal Oren, Mt. Carmel, including new records for Israel

Fifteen species of dermestid beetles were recorded at ‘Evolution Canyon’ (EC), Lower Nahal Oren, Mt. Carmel, Israel. They represent ~35% of known Israeli dermestid species. The following three species were recorded for the first time in Israel:Trogoderma svriaca Dalla Torre, 1911;Ctesias svriaca Ganglbauer, 1904; andAnthrenus (s.str.) jordaniens Pic, 1934. Adults of 13 species were collected on the more solar radiated, warmer and climatically more fluctuating south-facing slope (SFS); ten species were collected on the opposite, north-facing slope (NFS), which was cooler and climatically more stable. The abundance of adult dermestid beetles was 1.9 times higher on the SFS than on the NFS (86 and 47, respectively). Species richness and abundance distribution at EC (three collecting stations on each slope and one at the valley bottom) were significantly negatively correlated with the plant cover that consisted of trees and bushes (Spearmanr _s ,P=0.007 and 0.039, respectively) and perennials (Spearmanr _s ,P=0.039 and 0.077, respectively), indicating that non-woody plants were preferred by adult dermestid beetles.     

Epidemiology of Toxigenic Fungi and their Associated Mycotoxins for Some Mediterranean Crops

Recent data on the epidemiology of the common mycotoxigenic species of Fusarium, Alternaria, Aspergillus and Penicillium in infected or colonized plants, and in stored or processed plant products from the Mediterranean area are reviewed. Emphasis is placed on the toxigenicity of the causal fungal species and the natural occurrence of well known mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone, patulin, Alternaria-toxins and moniliformin), as well as some more recently described compounds (fusaproliferin, beauvericin) whose toxigenic potential is not yet well understood. Several Fusarium species reported from throughout the Mediterranean area are responsible of the formation of mycotoxins in infected plants and in plant products, including: Fusarium graminearum, F. culmorum, F. cerealis, F. avenaceum, F. sporotrichioides and F. poae, which produce deoxynivalenol, nivalenol, fusarenone, zearalenone, moniliformin, and T-2 toxin derivatives in wheat and other small grains affected by head blight or scab, and in maize affected by red ear rot. Moreover, strains of F. verticillioides, F. proliferatum, and F. subglutinans, that form fumonisins, beauvericin, fusaproliferin, and moniliformin, are commonly associated with maize affected by ear rot. Fumonisins, were also associated with Fusarium crown and root rot of asparagus and Fusarium endosepsis of figs, caused primarily by F. proliferatum. Toxigenic A. alternata strains and associated tenuazonic acid and alternariols were commonly found in black mould of tomato, black rot of olive and citrus, black point of small cereals, and black mould of several vegetables. Toxigenic strains of A. carbonarius and ochratoxin A were often found associated with black rot of grapes, whereas toxigenic strains of A. flavus and/or P. verrucosum, forming aflatoxins and ochratoxin A, respectively, were found in moulded plant products from small cereals, peanuts, figs, pea, oilseed rape, sunflower seeds, sesame seeds, pistachios, and almonds. Finally, toxigenic strains of P. expansum and patulin were frequently found in apple, pear and other fresh fruits affected by blue mould rot, as well as in derived juices and jams.     

A survey of the genera of<Emphasis Type="Italic">Microgaster</Emphasis> latreille and<Emphasis Type="Italic">Hygroplitis</Emphasis> thomson (Hymenoptera: Braconidae: Microgastrinae) from China

The genera ofMicrogaster Latreille 1804 andHygroplitis Thomson 1895 from China are presented systematically in this paper. Thirty-two species ofMicrogaster and three species ofHygroplitis are known in China. Diagnosis, character variation, distribution and host of each species among the two genera are presented, including its host and distribution. Keys to the species ofMicrogaster andHygroplitis are given. http://www.phytoparasitica.org posting Dec. 19, 2006.     

Plant Viruses Transmitted by Whiteflies

One-hundred and fourteen virus species are transmitted by whiteflies (family Aleyrodidae). Bemisia tabaci transmits 111 of these species while Trialeurodes vaporariorum and T. abutilonia transmit three species each. B. tabaci and T. vaporariorum are present in the European–Mediterranean region, though the former is restricted in its distribution. Of the whitefly-transmitted virus species, 90% belong to the Begomovirus genus, 6% to the Crinivirus genus and the remaining 4% are in the Closterovirus, Ipomovirus or Carlavirus genera. Other named, whitefly-transmitted viruses that have not yet been ranked as species are also documented. The names, abbreviations and synonyms of the whitefly-transmitted viruses are presented in tabulated form together with details of their whitefly vectors, natural hosts and distribution. Entries are also annotated with references. Whitefly-transmitted viruses affecting plants in the European–Mediterranean region have been highlighted in the text.     

Broad bean mottle virus in Morocco; curculionid vectors,and natural occurrence in food legumes other than faba bean (Vicia faba)

Broad bean mottle virus (BBMV) was transmitted from infected to healthy faba-bean plants by the curculionid weevilsApion radiolus Kirby,Hypera variabilis Herbst,Pachytychius strumarius Gyll,Smicronyx cyaneus Gyll, andSitona lineatus L. The latter appeared to be an efficient vector: acquisition and inoculation occurred at the first bite, the rate of transmission was c. 41%, and virus retention lasted for at least seven days.S. lineatus transmitted the virus from faba bean to lentil and pea, but not to the three genotypes of chickpea tested. This is the first report on the generaHypera, Pachytychius, andSmicronyx as virus vectors, and onA. radiolus, H. variabilis, P. strumarius, andS. cyaneus as vectors of BBMV.Out of 351 samples of food legumes with symptoms suggestive of virus infection, 16, 11, 19, and 17% of the samples of chickpea, lentil, pea, and common bean, respectively, were found infected when tested for BBMV in DAS-ELISA. This is the first report on the natural occurrence of BBMV in chickpea, lentil, pea, and common bean. The virus should be regarded as a food-legume virus rather than a faba-bean virus solely, and is considered an actual threat to food legume improvement programmes.     

Characterization of potato potyvirus Y (PVY) isolates from seed potato batches. Situation of the NTN, Wilga and Z isolates

A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVY^N strain and six to the PVY^O strain. No PVY^C was found. Two other isolates reacted serologically like PVY^O, but were unable to elicit a hypersensitive response from the Ny_tbr gene and probably represent the PVY^Z group. At the molecular level, these two isolates showed a combination of both PVY^O and PVY^N and could be recombinants of these strains. Another isolate reacted serologically like PVY^O, but induced vein necrosis in tobacco, like PVY^N-Wilga. Some PVY^N isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVY^NTN group. The PVY^NTN, PVY^N-Wilga and PVY^Z groups probably represent pathotypes within strains PVY^N and PVY^O, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.     

The autumn leafroller: Phenology,damage and parasitoids in a Dutch apple orchard

The phenology of the autumn leafroller,Syndemis musculana, a local pest of apple, was studied in order to forecast larval emergence. From 1983–1986, peak flight as determined with sexpheromone traps was always between 13–18 May. The duration of embryonic development was determined at various constant temperatures and used to estimate the periods of egg hatch in these four years. Each year, most eggs should have hatched in the second decade of June.Differences in attack rates between apple cultivars seem to be explained largely by the variation in picking time. Larvae are only half grown at the beginning of harvest (cv. James Grieve), and have gone into hibernation when the latest variety (cv. Golden Delicious) is picked. Moreover, the varieties Cox's Orange Pippin and Belle de Boskoop, picked about half time, are liable to receive additional damage by caterpillars brought with the picked fruits into storage.Various hymenopterous parasites were reared from caterpillars. As the only leafroller in the orchard which hibernates as mature larva,S. musculana may promote winter survival of some parasitoids, like the eulophidColpyclypeus florus.Samenvatting De fenologie van de herfstbladroller (Syndemis musculana Hübner), een incidentele plaag op appel, werd nader bepaald met het doel het uitkomen van de eieren te kunnen voorspellen. In 1983–1986 viel de piekvlucht, bepaald met behulp van feromoonvallen, steeds tussen 13 en 18 mei.De ontwikkelingsduur van de eieren bij verschillende constante temperaturen werd gebruikt om de periode van uitkomen te schatten. De meeste eieren zullen ieder jaar in de eerste helft van juni uitkomen.Geconstateerde verschillen in schade tussen appelrassen blijken goeddeels terug te voeren op verschillen in pluktijdstip. De rupsen van de herfstbladroller zijn pas half-was als de eerste appels eind augustus geplukt worden, terwijl tegen het einde van de oogst begin oktober de meeste al in winterslaap zijn. Met name tussentijdse rassen, als Cox's Orange Pippin and Schone van Boskoop, lopen extra schade op doordat grotere rupsen met de geplukte vruchten in de kist terecht komen.Uit de rupsen werden negen, al van andere boomgaardbladrollers bekende, sluipwespen gekweekt, Omdat deze bladrollersoort, als enige in de boomgaard, als volgroeide rups overwintert, lijkt zij bij uitstek geschikt als winterwaard.This study was carried out at the Experimental Orchard De Schuilenburg, Schuilenburg 3, 4041 BK Kesteren, the Netherlands, to which address correspondence should be addressed.     

Diagnostics,genetic diversity and pathogenic variation of ascochyta blight of cool season food and feed legumes

Molecular diagnostic techniques have been developed to differentiate the Ascochyta pathogens that infect cool season food and feed legumes, as well as to improve the sensitivity of detecting latent infection in plant tissues. A seed sampling technique was developed to detect a 1% level of infection by Ascochyta rabiei in commercial chickpea seed. The Ascochyta pathogens were shown to be genetically diverse in countries where the pathogen and host have coexisted for a long time. However, where the pathogen was recently introduced, such as A. rabiei to Australia, the level of diversity remained relatively low, even as the pathogen spread to all chickpea-growing areas. Pathogenic variability of A. rabiei and Ascochyta pinodes pathogens in chickpea and field pea respectively, appears to be quantitative, where measures of disease severity were based on aggressiveness (quantitative level of infection) rather than on true qualitative virulence. In contrast, qualitative differences in pathogenicity in lentil and faba bean genotypes indicated the existence of pathotypes of Ascochyta lentis and Ascochyta fabae. Therefore, reports of pathotype discrimination based on quantitative differences in pathogenicity in a set of specific genotypes is questionable for several of the ascochyta-legume pathosystems such as A. rabiei and A. pinodes. This is not surprising since host resistance to these pathogens has been reported to be mainly quantitative, making it difficult for the pathogen to overcome specific resistance genes and form pathotypes. For robust pathogenicity assessment, there needs to be consistency in selection of differential host genotypes, screening conditions and disease evaluation techniques for each of the Ascochyta sp. in legume-growing countries throughout the world. Nevertheless, knowledge of pathotype diversity and aggressiveness within populations is important in the selection of resistant genotypes.     

Characterization of Sclerotinia minor populations in Texas peanut fields

In the summer of 2004 an epidemic of sclerotinia blight of peanut, a disease caused by Sclerotinia minor, occurred in Texas in fields where the disease was never previously detected. The disease was observed on many plants within one of the fields (>3000 disease foci), although most foci were <1 m. It is hypothesized that these observations were inconsistent with the recent introduction of a monocyclic pathogen, even if disease developed under conducive environmental conditions. The pattern of disease is most suggestive of the presence of foliar (ascospore) infections, although air temperature was above the known limits for apothecia development if the pathogen had arrived in the field in 2004 peanut seed. To further examine this epidemic, 232 isolates were collected, across a variety of spatial scales spanning this field and other Texas peanut fields, and evaluated for aggressiveness, fungicide sensitivity and genotypic diversity. There was wide variation among isolates for the phenotypic characteristics measured, but there was no evidence that a genotypically unique, highly aggressive, and fungicide resistant isolate had been introduced or evolved. The predominant genotype, TX1, which contained 154 isolates, was found in every county and field population.     

Tumours of Begonia and some other ornamentals,induced by Corynebacterium fascians

In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten.