Effects of field and landscape variables on crop colonization and biological control of the cabbage root fly Delia radicum

Agriculture intensification has deeply modified agroecosystems from field to landscape scales. To achieve successful pest control using natural enemies, understanding species interactions over all scales remains a challenge. Using the cabbage root fly as a model, we studied whether field and landscape characteristics influenced colonization and infestation of broccoli fields by the pest and its control by natural enemies. We also determined whether species of different trophic level or host specialization would respond to environmental characteristics at the same spatial extent. During a multiple-species and multiple-spatial extent study in northwestern France, we recorded pest colonization and infestation in 68 fields, collected associated natural enemies and assessed crop damages. In each field, we considered management practices and characterized the surrounding landscape in 50–500 m-wide buffers. Our main findings are that Delia radicum and its main natural enemies respond to both field and landscape characteristics. Semi-natural areas supported both crop colonization by pests and natural enemy action. The pest and its enemies differed in their responses to field or landscape variables. Landscape elements such as field banks favored the movement of the pest while impeding the movement of some natural enemies. Pest pressure did not increase with the neighboring density of Brassica crops. The presence of natural enemies did not reduce crop damage but reduced pest emerging rates. Finally, specialist parasitoids responded to the landscape at larger spatial extents than generalists. These results outline the complexity of improving pest control through landscape management.     

Landscape cohesion: an index for the conservation potential of landscapes for biodiversity

In urbanising landscapes, planning for sustainable biodiversity occurs in a context of multifunctional land use. Important conditions for species persistence are habitat quality, the amount and configuration of habitat and the permeability of the landscape matrix. For planning purposes, these determinants should be integrated into simple indicators for spatial conditions of persistence probability. We propose a framework of three related indices. The cohesion index is based on the ecology of metapopulations in a habitat network. We discuss how an indicator for species persistence in such a network could be developed. To translate this network index into an area index, we propose the concept of spatial cohesion. Habitat cohesion and spatial cohesion are defined and measured for single species or, at best, for species profiles. Since species differ in their perception of the same landscape, different species will rate different values of these indices for the same landscape. Because landscapes are rarely planned for single species, we further propose the index of landscape cohesion, which integrates the spatial cohesion indices of different species. Indices based on these concepts can be built into GIS tools for landscape assessment. We illustrate different applications of these indices, and emphasise the distinction between ecological and political decisions in developing and applying such tools. This revised version was published online in August 2006 with corrections to the Cover Date.     

Landscape factors and how they influence whitefly pests in cassava fields across East Africa

Context

African production landscapes are diverse, with multiple cassava cultivars grown in small patches amongst a diversity of other crops. Studies on how diverse smallholder landscapes impact herbivore pest outbreak risk have not been carried out in sub-Saharan Africa.

Objectives

Bemisia tabaci is a cryptic pest species complex that cause damage to cassava through feeding and vectoring plant-virus diseases and are known to reach very high densities in certain contexts. However, the factors driving this phenomenon are unclear.

Methods

Bemisia density data in cassava across a large number of sites representing a geographic gradient across Uganda, Tanzania and Malawi were collected. We tested whether in-field or landscape factors associated with land-use patterns underpinned Bemisia density variability and parasitism.

Results

We found the B. tabaci SSA1 species dominated our study sites, although other species were also common in some cassava fields. Factors associated with the surrounding landscape were unimportant for explaining variability in adult density, but the in-field variables of cassava age and cultivar were very important. The density of nymphs and the parasitism of nymphs was heavily influenced by a diversity of landscape factors surrounding the field, including the size of focal cassava field, and area of cassava in the landscape. However, unlike the trend from many other studies on drivers of natural enemy populations, this pattern was not solely related to the amount of non-crop vegetation, or the diversity of crops grown in the landscape.

Conclusions

Our findings provide management options to reduce whitefly abundance, including describing the characteristics of landscapes with high parasitism. The choice of cassava cultivar by the farmer is critical to reduce whitefly outbreak risk at the landscape-scale.

     

Landscape diversity and field border density enhance carabid diversity in adjacent grasslands and cereal fields

Landscape Ecology - Permanent grasslands have declined across Europe since the agricultural intensification. Grassland vicinity, landscape heterogeneity and vicinity of hedgerows are enhancing...     

山东保护地大樱桃病虫害发生动态与防治措施

随着生态环境条件的改变,保护地大樱桃的病虫害发生情况与露地产生很大差异,表现为个别病虫发生时间提前,为害期延长,灰霉病、根朽病、穿孔病加重,桑白蚧、苹小卷叶蛾年发生增加1代。针对生产实际情况并结合防治试验,总结制定了相应的保护地大樱桃病虫害综合防治措施。     

桃园主要害虫的无公害防治

据多年的调查，发现桃园主要发生有以下几种主要害虫，它们对桃的产量危害很大，为了减少因虫害给广大果农造成的损失，我们针对这几种虫害进行了观察与防治，效果很好，下面将其防治措施逐一介绍。     

防治长柔毛野豌豆生草果园杂草茎叶处理剂筛选

【目的】筛选出有效防治果园长柔毛野豌豆生草田杂草的茎叶处理剂,为果园长柔毛野豌豆生草田杂草的化学防治提供参考。【方法】室内盆栽比较了8种除草剂对长柔毛野豌豆的安全性和常见杂草的生物活性,筛选药剂进行复配,进一步研究复配制剂的联合除草类型,测定其对长柔毛野豌豆的安全性及其在长柔毛野豌豆与杂草之间的选择性指数,并对复配制剂进行田间药效试验。【结果】灭草松、咪唑乙烟酸与精喹禾灵茎叶喷雾处理在2×田间推荐剂量下对长柔毛野豌豆安全。咪唑乙烟酸在长柔毛野豌豆与碎米莎草、马唐、牛筋草、狗尾草、播娘蒿、牛繁缕之间的选择性指数大于2.0;灭草松在长柔毛野豌豆与荠菜、播娘蒿、牛繁缕之间的选择性指数小于0.7,安全性差;精喹禾灵在长柔毛野豌豆与牛筋草、狗尾草、马唐之间的选择性指数大于8.8。联合作用测定结果表明咪唑乙烟酸与精喹禾灵按不同质量比复配后对马唐、牛筋草、看麦娘、牛繁缕、播娘蒿、荠菜的联合作用类型均为加成作用,其中以质量比2∶1复配后,选择性指数在2.4～8.9之间。田间试验结果显示：咪唑乙烟酸和精喹禾灵复配后在有效成分125～150 g·hm^-2剂量下,于杂草2～3叶期、长柔...     

伏牛山南麓猕猴桃主要害虫的发生与综合防治

通过连续6年的调查研究，摸清了伏牛山南麓危害猕猴桃的桑白蚧、草履蚧、斑衣蜡蝉等7种害虫的发生规律及生活习性，并提出了综合防治技术。     

核桃花粉离体萌发的培养基研究

以6a生云新早实核桃的新鲜花粉为试材,采用花粉离体培养法,研究了不同的培养基组分以及温度对核桃花粉萌发的影响。结果表明:1)在单因子试验中,蔗糖、H3BO3和CaCl2在一定质量浓度范围内,对核桃花粉萌发及花粉管生长起促进作用,但超过一定质量浓度时则起抑制作用;而氮、镁和钾对核桃花粉萌发不显著。2)在正交试验中,蔗糖、H3BO3和CaCl2对核桃花粉萌发有极显著的影响,核桃花粉最适的培养基为100g/L蔗糖+10mg/LH3BO3+40mg/LCaCl2,花粉的萌发率可以达到45.24%。3)核桃花粉离体培养的最适温度为25℃,培养温度过高或过低都会抑制核桃花粉的萌发和花粉管生长。     

Integration of soil solarization and chemical sterilization with beneficial microorganisms for the control of white root rot and growth of nursery apple

White root rot (Dematophora necatrix (Mart.)) is a serious disease of apple (Malus domestica Borkh) in nurseries and orchards in India. In 2002 and 2003, field experiments were conducted to integrate soil solarization with native isolates of Azotobacter chrococcum and vesicular–arbuscular mycorrhizal fungi and observe its effect on the incidence of white root rot and growth of the saplings. Apple seeds coated with two native isolates of A. chrococcum (AZUHF₁ and AZUHF₂) were sown in plots inoculated with 4 native isolates of va-mycorrhiza, i.e. AMUHF₁ (Glomus fesiculatum), AMUHF₂ (Glomus macrocarpum), AMUHF₃ (Glomus mosseae) and AMUHF₄ (Gigaspora sp.) in 14 different combinations and these plots were solarized with transparent polyethylene mulch (25 μm thick) for 40 days in summer months. Soil solarization resulted around 9 °C higher temperature with average maximum temperature of 38–39 °C. Inoculation of saplings with AMUHF₁ isolate of va-mycorrhiza and AZUHF₁ isolate of A. chrococcum and then their planting in solarized soil was found most effective with no incidence of white root rot in comparison to 33.6–35.4% in control accompanied with 78–113% increase in shoot length and 81.6–84.3% increase in root length. Shoot and root length of the saplings was 9.6–10.6 and 9.2–16.0% higher, respectively, in solarized plots in comparison to sterilized plots.     

Landscape regularity modelling for environmental challenges in agriculture

In agricultural landscapes, methods to identify and describe meaningful landscape patterns play an important role to understand the interaction between landscape organization and ecological processes. We propose an innovative stochastic modelling method of agricultural landscape organization where the temporal regularities in land-use are first identified through recognized Land-Use Successions before locating these successions in landscapes. These time–space regularities within landscapes are extracted using a new data mining method based on Hidden Markov Models. We applied this methodological proposal to the Niort Plain (West of France). We built a temporo-spatial analysis for this case study through spatially explicit analysis of Land-Use Succession dynamics. Implications and perspectives of such an approach, which links together the temporal and the spatial dimensions of the agricultural organization, are discussed by assessing the relationship between the agricultural landscape patterns defined using this approach and ecological data through an illustrative example of bird nests.     

冬暖式大棚草莓与黄糯玉米轮作的技术

2003年开始,于莱州市平里店镇河西宋家村进行冬暖式大棚草莓与黄糯玉米轮作,收到良好的经济效益.现将其栽培技术总结如下.     

探寻中国古典园林与现代景观设计的交融之路——北京大观园酒店庭院景观设计

中国传统文化源远流长,是现代景观设计汲取营养和挖掘内涵的重要宝库。以北京大观园酒店庭院景观设计为例,来分析如何继承和发展中国古典园林设计理念及空间处理手法,并与现代景观设计的重要特性——大众公共活动空间的特性相结合,从而营造既符合现代都市居民的需求,又亲近自然的多元化景观空间。这有助于具有地域特色、时代特色和民族特色的标志性景观的创建,从而避免因盲目模仿而产生的雷同作品。     

Landscape – What’s in it? Trends in European Landscape Science and Priority Themes for Concerted Research

Reflecting on the other papers in this special issue, this synopsis characterises some essential trends in European Landscape Ecology, including the challenges it is facing in society. It describes the various perspectives on the ‘contents’ of landscape that are currently being practiced, and especially considers the notion of ‘environment’ as something intrinsic to human activity. Landscape classification and typology are discussed in their potential but limited use for landscape science. The specificity of the European approach appears to be related to the large diversity of cultural landscapes, currently losing their functional ties with the land-use systems that had formed them. European landscape research reports show a large commitment to this decreasing diversity, a dedication characterised by a strong sense of ‘loss and grief’. On the other hand, it is concluded that European landscape research has a specific niche with a clear focus on applied landscape studies explicitly including people’s perceptions and images, as well as the participation of the public and stakeholders. Since globalisation tends to reinforce the detachment of people from their environment; an increased effort is needed to compensate for this effect, and therefore the consideration of the various dimensions of the landscape is today more pertinent than ever. Meeting the challenges of present landscapes, in the face of new multifunctional demands in old diverse landscapes, requires more than before the combination of various perspectives and methods, and of various scales of application, in order to design innovative and adaptive paths for the future.     

枯草芽孢杆菌防治果实采后病害的研究进展

果实采后病害严重影响水果的贮藏及果品质量。因化学杀菌剂在应用中存在危害人体健康及污染环境等一系列问题,利用枯草芽孢杆菌(Bacillus subtilis)防治果实采后病害的生物防治手段作为一种有效替代方法受到人们的广泛关注。枯草芽孢杆菌是革兰氏阳性细菌研究的模式菌株,为重要的生防菌源。在探讨枯草芽孢杆菌防治果实采后病害拮抗机制的基础上,阐述了该领域的研究成果和最新进展,展示了枯草芽孢杆菌应用于果实采后病害生物防治的可行性和潜力,为今后果实采后生防产品的开发提供新的研究思路。     

Effect of matrix habitat on the spread of flea beetle introductions for biological control of leafy spurge

Matrix habitats are known to influence the movement patterns of a variety of species but it is less well known whether these effects have strong implications for spatial population dynamics, including the spread of biological introductions. Using a spatially explicit simulation model parameterized with empirical data, we examine how grass and shrub matrix habitats, each offering different resistance to dispersal, influence the spread and impact of a biocontrol agent, Aphthona lacertosa, on the invasive weed, leafy spurge. Model predictions indicate that differential responses to matrix habitat have little effect on the agent’s spread over the study landscape and this is supported by statistical models fit to observed A. lacertosa incidence on the same landscape. Subsequent experimentation with the simulation model suggested that A. lacertosa colonization rates were largely unaffected by increases in amount of the more restrictive shrub matrix. However, simulations of an hypothetical species with greater overall dispersal ability but reduced dispersal rate through shrub matrix showed that colonization rates were noticeably reduced when the percentage of shrub matrix on the landscape approached 50%. Combined these results suggest that some tailoring of release strategies may be required to accommodate the unique dispersal capabilities of different biocontrol agents on particular release landscapes, but for A. lacertosa there appears to be little effect of matrix habitat structure on rates of spread.     

梨花粉矿质营养成分的能谱分析

对9个梨品种花粉表面微区进行ESCA(Electron Spectroscopy for Chemical Analysis,能谱分析)11种矿质营 养成分分析,结果表明:(1)所测的11种元素平均含量,以P元素相对含量最高,占原子百分比的25.95％,其次为S 22.02％,K 15.80％,Mg 7.93％,Na 5.80％,Si 5.65％,Fe 5.11％,Cl 3.83％,Ca 3.29％,Cu 2.55％,Zn 2.07％;(2)不同梨品种 矿质元素含量也有不同,P含量最高的为酥梨,最低是硕丰,S含量最高的是硕丰,最低的为酥梨,K含量最高的是马 蹄黄,最低的为黄花,Ca含量最高的是丰水,最低的是酥梨;(3)花粉表面不同部位元素含量也不同,萌发沟高于沟间 区的元素有Na、Mg、Si、S、Ca、Fe、Cu,沟间区高于萌发沟的元素有Cl、K、Zn,而P含量在2个区域相差不大。     

棕榈科植物在西南地区园林应用的策略与方法

棕榈科是独特的园林观赏植物。针对棕榈科植物应用的策略与方法,提出全局观、系统观、运动观和辩证观;针对目前应用中存在的问题,介绍了差异化造景策略,配置的原则与技巧,实地实树的引种原则,以及移栽养护技术。     

常见彩叶树种在北方园林绿化中的应用

在介绍春色叶类、彩色叶类、常色叶类、斑色叶类等常见的彩叶树种基础上,指出了彩叶树种在园林绿化中应遵循生物学习性和生态习性相结合、观赏效果与生态功能相结合,并符合美学原理等原则,分析了彩叶树种在北方的应用现状和存在的问题,并提出了应扩大优良彩叶树种的引种、提高优良彩色树种的抗性、丰富优良彩叶树种、加强乡土树种的开发等建议。     

生物菌肥防治寒地苹果树重茬病的研究

为了解木美土里生物菌肥防控寒地苹果树重茬病的效果,连续2年(2016年和2017年)研究了不同生物菌肥用量对重茬土壤上定植龙丰/山定子苹果树生长发育的影响。结果表明,与对照相比,施用生物菌肥显著提高了苹果的生长量、分枝数和叶片叶绿素含量,其中以0.50 kg/株木美土里处理效果最好。2016年和2017年,0.50 kg/株木美土里处理的株高分别为不施用生物菌肥对照的1.52、1.53倍,茎粗分别为对照的1.27、1.35倍,茎粗增长量分别为对照的1.22、1.66倍,分枝数分别为对照的2.42、2.32倍。除2016年0.25 kg/株处理外,其他处理均明显提高了叶片叶绿素含量。因此,0.50 kg/株木美土里生物菌肥处理对寒地苹果重茬障碍的防治效果最佳,可应用于苹果树寒地重茬栽培。