克里雅绿洲浅层地下水与土壤特征的局部空间关系

通过优选的空间插值方法、网格单元法、地理加权回归(GWR)与最小二乘法(OLS)等方法的综合运用,系统研究典型干旱区绿洲的浅层地下水特征(埋深、电导率)与表层土壤特征(含水率、电导率)的空间分异与局部空间关系。结果表明:空间拟合方法上,表层土壤电导率与含水率的空间关系回归适用OLS模型,其余指标间空间关系采用GWR模型更优;空间关系上,土壤电导率与含水率的全局相关系数为极显著的0.85,局部相关性上绿洲西部明显高于东部;土壤电导率与地下水电导率的全局相关系数极显著(R=0.602),但局部相关性上同时具有正相关与负相关特征;土壤含水率与埋深、地下水电导率与埋深均呈全局负相关,但在局部出现正相关;地下水埋深由绿洲西北至东南逐渐增加,地下水电导率由西南至东北依次呈现低—高—低的特征,表层土壤电导率与含水率由西至东均呈现低—高—低—次高的特征; GWR较OLS方法能够反映更多的空间异质特征,通常在总体相关水平下,局部可能出现相关性相反或大小不同的相关性。     

Modelling within‐field spatial variability of crop biomass – weed density relationships using geographically weighted regression

The objective of this study is to offer a new framework for exploring and modelling the spatial variation in crop biomass – weed density relationships, adapting geographically weighted regression (GWR) to include a non‐linear regression model. The relationship between crop biomass and weed density is usually modelled by non‐linear regression models, in which the spatial heterogeneity of the relationship is ignored, although the effect of weeds on crop can differ in relation to topographic and edaphic variability. GWR attempts to capture spatial variability by calibrating a regression model to each location in space. We show the application of the method in different cereal cropping systems, with one or two weed species. The results indicate that GWR can significantly improve model fitting over non‐linear least squares (NLS) in some situations. Furthermore, the parameter estimates can be mapped to illustrate local spatial variations in the regression relationship under study and eventually to relate the spatial variability of the model to the environmental heterogeneity. We discuss the value of the GWR for analysing the observed spatial variability and for improving model development and our understanding of spatial processes.     

Spatial regression analysis of Ceratitis capitata Wiedemann (Diptera: Tephritidae) on Terceira Island,Azores

The fruit fly Ceratitis capitata Wiedemann is one of the most important threats to the trade of fresh fruits in the world due to its ability to survive in a wide range of hosts and climatic conditions. The main goal of this study is to evaluate if there is any significant relationship between the abundance of wild adults of C. capitata and the spatial characteristics of the location. The ordinary least squares estimation model calculated for each gender cannot provide a satisfactory general explanation for abundance of both genders of wild adults, yet it might generate some hypotheses about wild adult females of C. capitata fruit-seeking behaviour. Results from geographically weighted regression analysis can provide a satisfactory general explanation for abundance of both genders of wild adults. Both methods suggest that males are more dispersed than females, and because of that they might play an important role in scouting the surroundings for additional fruit hosts. The presence of some host-plants, even in places offering less protection (like pasture areas), provides an ecological corridor that supports the spread of wild adults of C. capitata.     

基于条件植被温度指数的冬小麦主要生育时期干旱监测效果评价——Ⅱ.改进的层次分析法和变异系数法组合赋权

运用改进的层次分析法、变异系数法及主客观组合赋权法确定关中平原冬小麦越冬后主要生育时期干旱对产量的影响权重,建立关中平原五市2002—2009年每年的加权条件植被温度指数(VTCI)与冬小麦单产的一元线性回归模型,分析VTCI与产量间的线性关系。结果表明,变异系数法确定的加权VTCI与小麦单产的线性相关性不显著,渭南、咸阳及铜川的决定系数R²值均低于0.5;改进的层次分析法和组合赋权法确定的加权VTCI与小麦单产的线性相关性显著,除铜川外其余四市的R²值接近0.5,或者高于0.6,且组合赋权法的结果中西安的R²值达到0.7。基于改进的层次分析法和变异系数法的归一组合赋权法的结果优于其它 主客观组合赋权法的结果,为最优赋权方法,可用于评价冬小麦主要生育时期的干旱监测效果。     

Assessing the impacts of human activities and climate variations on grassland productivity by partial least squares structural equation modeling(PLS-SEM)

The cause-effect associations between geographical phenomena are an important focus in ecological research. Recent studies in structural equation modeling(SEM) demonstrated the potential for analyzing such associations. We applied the variance-based partial least squares SEM(PLS-SEM) and geographically-weighted regression(GWR) modeling to assess the human-climate impact on grassland productivity represented by above-ground biomass(AGB). The human and climate factors and their interaction were taken to explain the AGB variance by a PLS-SEM developed for the grassland ecosystem in Inner Mongolia, China. Results indicated that 65.5% of the AGB variance could be explained by the human and climate factors and their interaction. The case study showed that the human and climate factors imposed a significant and negative impact on the AGB and that their interaction alleviated to some extent the threat from the intensified human-climate pressure. The alleviation may be attributable to vegetation adaptation to high human-climate stresses, to human adaptation to climate conditions or/and to recent vegetation restoration programs in the highly degraded areas. Furthermore, the AGB response to the human and climate factors modeled by GWR exhibited significant spatial variations. This study demonstrated that the combination of PLS-SEM and GWR model is feasible to investigate the cause-effect relation in socio-ecological systems.     

Mediterranean fruit fly suppression using chemosterilants for area‐wide integrated pest management

BACKGROUND: The chemosterilisation technique has been demonstrated to reduce the population and fruit damage of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in citrus orchards. Field trials showed efficacy by reducing the fruit fly population, which was progressively achieved by continuous application of lufenuron to several generations. Different authors have suggested that field trials should be carried out in isolated or wide areas in order to reduce fruit fly intrusion and obtain best results. To this end, a wide‐area trial over 3600 hectares has been under investigation in Valencia (Spain) since 2002 to validate the chemosterilisation technique against the fruit fly. The whole area was treated with 24 traps ha^?1, using more than 86 000 traps in the field trial. RESULTS: A continuous decrease in fruit fly population was observed over the 4 years under trial. Moreover, results showed a significant reduction in persimmon damage in the chemosterilant treatment area compared with a malathion aerial treatment area. In the case of citrus damage, no significant differences were obtained between malathion and chemosterilant treatments. CONCLUSION: The chemosterilant method reduces Mediterranean fruit fly populations, and therefore it is a candidate treatment to replace aerial treatments with insecticides in order to suppress this pest. In addition, the efficacy of chemosterilant treatment is increasing year after year. The possibility of using this technique combined with other control methods is discussed. Copyright © 2010 Society of Chemical Industry     

Development and use of a forecasting model for Cydia pomonella*

For more than 10 years, a forecasting model for Cydia pomonella in apple orchards, worked out by the French NPPO, has described the development of emergence cohorts in spring, and followed their development and descent, through the whole agricultural season. In homogeneous areas, this tool, still under development, can be used to define periods for effective treatment (ovicides, larvicides, mating disruption) and the tolerance for codling moth levels in various situations. Alternation of insecticides is provided for, so as to manage resistance phenomena. The reliability of the model is based on rigorous continuous biological checks on the forecasts made by the algorithm, on scientific surveillance by INRA and on regular collaboration between the advisers involved and the agrometeorological services. The model forms part of a wider decisional scheme, or expert system, in which the fruit grower and his adviser provide observations on the changes which cannot be provided by the model: installation of hail protection nets, night lights, fruit spreading. More parameters will be incorporated in future and the geographical validity of the model will be extended, particularly to more northerly areas.     

基于气温的潜在蒸散发量估算方法在我国西北干旱地区的应用比较

根据石羊河流域两个气象站的历史数据,选取7种基于气温的潜在蒸散发量估算方法,以FAO56-PM法计算的ET作为参考值,对其进行比较分析,最后再用实测蒸发皿蒸发量对这些方法在西北干旱地区的适用性进行评价。结果表明:在两个站使用7种方法的初始参数时,多数产生较大误差。校正参数后两个站所有方法在估算逐月ET和月平均ET时都得到明显改进。改进的Romanenko法在两个站所有月份以及全年误差都最小,其次是Hargreaves和Linacre法。用实测小型蒸发皿蒸发量进行验证时,改进的Romanenko法与其相关系数最高,为0.97,其次是Linacre和Hargreaves法。就气温法而言,校正参数后的Romanenko,Hargreav-es和Linacre法可在此研究区域用于估算ET,并建议优先选择Romanenko法,与小型蒸发皿的折算系数适宜选取0.60。     

Genetic diversity and a PCR-based method for Xanthomonas axonopodis detection in passion fruit

Xanthomonas axonopodis pv. passiflorae causes bacterial spot in passion fruit. It attacks the purple and yellow passion fruit as well as the sweet passion fruit. The diversity of 87 isolates of pv. passiflorae collected from across 22 fruit orchards in Brazil was evaluated using molecular profiles and statistical procedures, including an unweighted pair-group method with arithmetical averages-based dendrogram, analysis of molecular variance (AMOVA), and an assigning test that provides information on genetic structure at the population level. Isolates from another eight pathovars were included in the molecular analyses and all were shown to have a distinct repetitive sequence-based polymerase chain reaction profile. Amplified fragment length polymorphism technique revealed considerable diversity among isolates of pv. passiflorae, and AMOVA showed that most of the variance (49.4%) was due to differences between localities. Cluster analysis revealed that most genotypic clusters were homogeneous and that variance was associated primarily with geographic origin. The disease adversely affects fruit production and may kill infected plants. A method for rapid diagnosis of the pathogen, even before the disease symptoms become evident, has value for producers. Here, a set of primers (Xapas) was designed by exploiting a single-nucleotide polymorphism between the sequences of the intergenic 16S-23S rRNA spacer region of the pathovars. Xapas was shown to effectively detect all pv. passiflorae isolates and is recommended for disease diagnosis in passion fruit orchards.     

海南油棕果腐病的病原鉴定及发病条件的研究

三年来作者对于幼龄結果油棕的果穗和果实腐烂的症状、分布、蔓延为害,其发生条件和栽培管理的关系进行了詳細的調查和观察,并进行了病原分离、培养、田间人工接种和試探性化学保护等試驗。同时对果实离层組織的形成进行了切片检查。 結果指出海南十二个地区的幼龄结实棕园普遍出現的花、果、穗腐与环境条件和栽培管理有密切关系。果腐是果实离体后从蒂部組織开始的。从腐果組織中經常可以分离到細菌、炭疽菌和鐮刀菌。多次田間接种証明这些菌对健康果实和果穗均无致病能力。大田喷药无效。看来,油棕果腐病是由于环境坏、管理差的条件下,未成熟或接近成熟的果实产生离层而与果柄分离,再由外界杂菌腐食脫果而致腐烂。可見,本病是屬于非侵染性的生理病害。     

宁夏沙湖旅游开发对水体环境的影响

选取溶解氧、悬浮物、生化耗氧量、氨氮、总磷和氟化物6个评价因子,采用加权综合模型对沙湖不同功能区水质状况,以及1991年以来水质变化趋势与旅游人数变化的耦合性分析,反映出沙湖水体环境质量变化主要受旅游开发影响所致。     

Willingness to pay for area-wide management and sterile insect technique to control fruit flies in Australia

Abstract

Fruit flies are a biosecurity threat to international trade of horticultural produce around the world. Area-wide management (AWM) of fruit flies offers a promising solution to coordinate farmers’ activities to fight against the spread of this pest. The incorporation of the sterile insect technique (SIT) may increase the effectiveness of AWM and lead to greater suppression and possible eradication of the fruit fly pest. This article presents findings from a choice experiment survey to ascertain the willingness to pay (WTP) for the benefits of a suite of AWM features and SIT. These features include the benefits from (1) coordinated fruit fly monitoring, (2) coordinated on-farm male annihilation of fruit flies, (3) management of fruit fly in residential areas, and (4) coordinated release of sterile flies. This is the first study of its kind to assess the WTP for AWM and SIT in a developed country. Results suggest that growers are willing to pay for SIT and coordinated fruit fly management in residential areas but are not willing to pay for other coordinated services that they are already practicing on their farms.     

STREP: a brown‐spot disease predictor for scheduling fungicide sprays against Stemphylium vesicarium on pear*

Brown spot of pear (Pyrus communis) caused by Stemphylium vesicarium is an important disease in fruit‐growing areas of Europe. The control of brown spot is based on protectant sprays of fungicide applied, at 7‐ to 15‐day intervals depending on the type of fungicide, from fruit set to preharvest regardless of the risk of infection. A forecasting model has been developed and can be used for timing the fungicide applications and to eliminate unnecessary sprays. The model quantifies the relationship between wetness duration and temperature in disease severity and can be used as a tool for the prediction of disease infection periods. The capacity of risk prediction was validated over 2 years. The fungicide sprays scheduled by the STREP forecaster were evaluated in commercial orchards during 3 years in different climatic areas in Spain and Italy. The results showed consistently that use of the STREP model minimized the number of fungicide sprays compared with a protectant schedule, but without decreasing the quality of commercial disease control. The susceptibility of selected European pear cultivars to infection by S. vesicarium and the influence of fruit age were also determined. The implementation of the model in warning stations will require the combination of predictions by the STREP model, the level of inoculum and the sensitivity of phenological stage and pear cultivar.     

橘小实蝇在上海局部暴发成因分析

橘小实蝇是近年来传入上海并局部暴发危害的检疫性有害生物。本文根据上海地区实蝇监测及现场调查的结果,从入侵生物的一般特点着手分析橘小实蝇传入上海并暴发的成因。结果表明:橘小实蝇通过水果贸易传入到上海,废弃水果的无效管理是造成橘小实蝇疫情传入的重要原因;上海自然气候适合橘小实蝇的生存与繁殖,桃、梨、李等大量的寄主植物为其生存和种群扩张提供了充足的食物源。     

樱桃小果病毒1号胶体金免疫层析试纸的研发与应用

近年来，病毒病在甜樱桃主产区的发生呈上升趋势，制约了甜樱桃产业升级和发展。能够侵染甜樱桃的病毒种类中，樱桃小果病毒1号(little cherry virus 1,LChV-1)导致樱桃果实缩小，彻底丧失经济价值，对甜樱桃产量影响较大。LChV-1通常具有潜伏侵染的特性，在樱桃苗期难以通过症状进行判断。同时，多数品种对LChV-1敏感，因此该病毒的早期检测对甜樱桃的生产尤为重要。传统的病毒检测手段需要专业仪器，不能满足田间快速检测的需求。本研究获取了LChV-1外壳蛋白的多克隆抗体，并研发了一种能够准确检测LChV-1病毒的胶体金免疫层析试纸，确定了胶体金的最佳抗体标记浓度为0.24 mg/mL,检测线最佳重组蛋白浓度为0.25 mg/mL,质检线最佳羊抗兔IgG抗体浓度为0.04 mg/mL。运用该试纸检测只需10～15 min,检测时间短、成本低、结果容易判断，可用于田间快速检测。本研究为樱桃小果病的综合防控提供了有效的监测和检测手段。     

采用果园喷雾施药机械施药时农药有效沉积率的计算方法

针对传统农药沉积率测算方法无法精确反映果园中农药实际利用率的问题,提出一种结合果树冠层特征与叶面沉积量直接测算农药药液在果树靶标上有效沉积率的方法,以期建立一种适用于不同栽种模式的果园通用农药沉积率计算方法。首先采用传统方法计算采用风送式自走喷雾机喷雾后农药在乔化稀植型果园的地面流失率,将其结果与采用果树冠层特征与叶面沉积量相结合的方法计算的有效沉积率进行比较,再通过计算采用风送式自走喷雾机喷雾后农药在矮砧密植型果园的有效沉积率以及采用担架柱塞泵式喷雾机和植保无人飞机喷雾后农药的有效沉积率,验证本研究所提出的将果树冠层特征与叶面沉积量相结合计算农药有效沉积率方法的准确性及适用性。结果表明:基于叶面沉积量结合果树冠层特征方法计算得到的农药有效沉积率与采用传统方法计算得到的农药地面流失率结果基本一致,均能体现施药机械的农药利用率,但比较而言,本研究所提出的方法在果园植保机械喷雾施药有效利用率的影响因素方面考虑更全面,兼顾了叶面沉积量和果树冠层结构的影响,且对于不同栽种模式下的果园更具适应性。将果树冠层特征与叶面沉积量相结合进行果园农药有效沉积率的计算,可以更加真实地反映出果园农药的实际利用情况,同时通过将果树冠层结构量化为叶面积指数、冠层阴影面积等指标,可以为不同栽种模式下的果园选择适宜的植保机械,结合地面流失率的测量,计算出果园农药的飘移量,从而通过调整喷雾角度、雾滴大小、喷雾流量等参数,实现对植保机械的优化,达到精准施药的目的。     

Spatial modelling indicates Striga seedbank density dependence on rainfall and soil traits in the savannas of northern Nigeria

Striga is one of most notorious weeds devastating crop production in the dry savannas of northern Nigeria. The weed attacks most cultivated cereals and legumes with crop losses as high as 100% when no control measure is employed. Studies conducted in the dry savannas of Nigeria indicated that Striga seedbank is strongly related to soil and climate properties. This study was conducted to model Striga hermonthica seedbank zones in the dry savannas of Nigeria based on soil and climate properties of the areas. Using multi-stage spatial sampling, 169 soil samples were collected at the centroids of 25 × 25 km grids across the study area and analysed for physico-chemical properties. The number of Striga seeds were counted from the soil samples using water elutriator and potassium bicarbonate method. Daily temperature, relative humidity and rainfall for each point were downloaded from Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS). Minimum and maximum temperatures, and relative humidity were accessed from National Aeronautics and Space Administration (NASA POWER). Thresholds of various soil and climate variables for optimum concentration of Striga seedbank were analysed using boundary line analysis (BLA). From the BLA, optimum amount of rainfall for high Striga seedbank was 549 mm per annum. While temperature has a wide suitability range for Striga seedbank development. Principal component analysis was used to reduce dimensionality of the dataset into principal components (PCs). Seven PCs which explained 75.6% variation in the data were retained and used in the weighed overlay modelling (WOM). The weighted overlay map produced five distinct Striga seedbank zones; very low, low, moderate, high and very high. More than 60% of the study area had moderate to high Striga seedbanks. The zones vary mostly based on soil, climate and Striga seed count. The establishment of the optimum levels of the environmental factors at which Striga seedbank is favoured will assist in designing a more site-specific Striga management. However, for scalability purpose, adoption of the Striga zoning approach can be useful.     

The efficiency of a vacuum device for estimating soil-surface seed abundance on lowland farms

Accurate sampling methods for estimating soil-surface seed abundance in agro-ecosystems are vital for understanding arable plant population dynamics, as well as quantifying seed availability as a food resource for farmland birds, mammals and arthropods. We tested the sampling efficiency of a portable, petroleum spirit powered leaf blower-vacuum in recovering four different seed size classes on the soil-surface of seven lowland farm habitats. Vacuum sampler efficiency was dependent on seed size, habitat type and exposure of seeds to environmental conditions. Larger seeds were more readily recovered and overall seed recovery was consistently higher on habitats with low vegetation cover, such as newly-sown cereal fields. We discuss the limitations of the device, but commend its use with correction factors to estimate soil-surface seed abundance in agricultural habitats. This study highlights the potential biases when estimating soil-surface seed abundance, the importance of correcting such biases and the need for better sampling techniques for weed science.     

Evaluation of neonicotinoid, organophosphate and avermectin trunk injections for the management of avocado thrips in California avocado groves

BACKGROUND: Trunk injections of systemic insecticides were evaluated for the management of avocado thrips. Insecticide residues were quantified in leaves to determine when after treatment, and for how long, toxic concentrations of the insecticides were present. Residues in fruit were quantified to determine whether trunk injection of insecticides might present a greater risk than traditional application methods for contaminating fruit. RESULTS: Residues of imidacloprid and dinotefuran were at least tenfold higher in leaves when trees were treated via trunk injection compared with soil application. Dinotefuran uptake was more rapid than imidacloprid, and no residues were detected within fruit. Acephate was also mobilized very rapidly and gave good control of thrips in bioassays; however, residues of acephate and its insecticidal metabolite methamidophos were detected in the fruit for up to 4 weeks after injection. Avermectin uptake was very slow, and it was ineffective against avocado thrips. CONCLUSIONS: Trunk injections of acephate and dinotefuran permitted rapid uptake into avocados, and they are strong candidates as control methods for avocado thrips. However, residues of organophosphates in fruit could necessitate increased preharvest intervals. Residues of neonicotinoids were below detection limits in fruit, suggesting that neonicotinoids may be the more suitable control option of the two chemical classes. Copyright © 2012 Society of Chemical Industry     

东亚飞蝗蝗蝻抽样的研究

自五十年代以来,应用于东亚飞蝗蝗区估计蝗蝻种群密度的抽样方法,是样方为10平方尺的筒单随机抽样。本文是以抽样数、抽样消耗、相对精确度为标准,对三种抽样模型、三个抽样单位进行了比较。根据这些结果,我们提出了在当前蝗蝻密度较低的情况下,应采用样方为100平方尺的最适配额分层抽样。这种抽样方法在精确度方面可以高出现用的抽样方法2倍以上。而抽样时间消耗可相对节约一半以上。