Organic farming in isolated landscapes does not benefit flower-visiting insects and pollination

Organic farming has often been found to provide benefits for biodiversity, but the benefits can depend on the species considered and characteristics of the surrounding landscape. In an intensively farmed area of Northeast Italy we investigated whether isolated organic farms, in a conventionally farmed landscape, provided local benefits for insect pollinators and pollination services. We quantified the relative effects of local management (i.e. the farm system), landscape management (proportion of surrounding uncultivated land) and interactions between them. We compared six organic and six conventional vine fields. The proportion of surrounding uncultivated land was calculated for each site at radii of 200, 500, 1000 and 2000 m. The organic fields did not differ from the conventional in their floral resources or proportion of surrounding uncultivated land. Data were collected on pollinator abundance and species richness, visitation rates to, and pollination of experimental potted plants. None of these factors were significantly affected by the farming system. The abundance of visits to the potted plants in the conventional fields tended to be negatively affected by the proportion of surrounding uncultivated land. The proportion fruit set, weight of seeds per plant and seed weight in conventional and organic fields were all negatively affected by the proportion of surrounding uncultivated land. In vine fields the impact of the surrounding landscape was stronger than the local management. Enhancement of biodiversity through organic farming should not be assumed to be ubiquitous, as potential benefits may be offset by the crop type, organic-management practices and the specific habitat requirements in the surrounding landscape.     

Soil fertility management and insect pests: harmonizing soil and plant health in agroecosystems

Cultural methods such as crop fertilization can affect susceptibility of plants to insect pests by altering plant tissue nutrient levels. Research shows that the ability of a crop plant to resist or tolerate insect pests and diseases is tied to optimal physical, chemical and mainly biological properties of soils. Soils with high organic matter and active soil biology generally exhibit good soil fertility. Crops grown in such soils generally exhibit lower abundance of several insect herbivores, reductions that may be attributed to a lower nitrogen content in organically farmed crops. On the other hand, farming practices, such as excessive use of inorganic fertilizers, can cause nutrient imbalances and lower pest resistance. More studies comparing pest populations on plants treated with synthetic versus organic fertilizers are needed. Understanding the underlying effects of why organic fertilization appears to improve plant health may lead us to new and better integrated pest management and integrated soil fertility management designs.     

Effect of agricultural management practices on arbuscular mycorrhizal fungal abundance in low-input cropping systems of southern Africa: a case study from Zimbabwe

Previous research, mostly in temperate agricultural systems, has shown that management practices such as fallow period, tillage, crop rotation, and phosphorus (P) fertilizer applications can influence the abundance of arbuscular mycorrhizal fungi (AMF), but relatively little is known about their effect in smallholder farmers’ fields in sub-Saharan Africa. In this study, we evaluated the effect of four subsistence crops that form associations with AMF, moderate P fertilization, tillage, and fallow period on the subsequent AMF abundance on three contrasting low fertility soils in south-western Zimbabwe. Arbuscular mycorrhizal fungal abundance was estimated based on early mycorrhizal colonization of maize (Zea mays L.) or lablab (Lablab purpureus L.) following the various treatments. The previously grown crop significantly affected AMF abundance (p < 0.001). It was highest after lablab followed by pigeonpea (Cajanus cajan L.), maize, and groundnut (Arachis hypogaea L.), and there were significant positive correlations between AMF abundance and aboveground biomass of pigeonpea, lablab, and maize. Contrary to much previous research, P fertilization, fallowing, and tillage did not significantly decrease AMF abundance. In smallholder farmers’ fields in the semi-arid tropics of sub-Saharan Africa, therefore, growing vigorous mycorrhizal plants prior to the dry season could be more important than minimizing P fertilizer applications, fallow periods, and tillage to maintain or increase AMF abundance.     

多样化田景观的生态功能研究

海河低平原区农田景观存在的主要问题是作物景观元素的水平分布日趋单一化,造成了农田景观生态不稳定性。本文采用了景观生态学的基本原理与方法，研究明确了多样化农田景观可减轻病虫害的发生并具有改善田间小气候的微气候效应，对景观单元规格及不同景观元素组合与虫害发生的关系进行了探讨，为实施农田景观生态调控技术，提高生态稳定性提供了理论依据。     

基于改进深度置信网络的大棚冬枣病虫害预测模型

导致冬枣病虫害发生的原因很多而且很复杂,利用传统的数学方法和神经网络(neural network,NN)很难建立正确的病虫害预测模型.由于典型的深度置信网络(deep belief network,DBN)的各层之间缺乏有监督训练,使得网络误差逐层向上传递,降低了预测模型的预测率.针对这些问题,引入冬枣病虫害的先验信息,提出一种基于环境信息和改进DBN的冬枣病虫害预测模型.在该模型中,通过无监督训练和有监督微调从冬枣生长的环境信息序列中获取可表征冬枣病虫害发生的深层特征的隐层参数,并形成新的特征集,然后在预测模型的顶层通过一个后向传播神经网络(back propagation neural network,BPNN)进行病虫害预测.从2014—2017年的4 a时间内,利用农业物联网传感器采集30个大棚冬枣常见的2种虫害和3种病害发生的环境信息序列6000多条,由此验证所提出的预测模型,平均预测正确率高达84.05%.与基于强模糊支持向量机、改进型NN和BPNN的3种病虫害预测模型进行了试验比较,预测正确率提高了20多个百分点.试验结果表明,该模型极大提高了大棚冬枣病虫害的预测正确率.该研究可为大棚冬枣病虫害预测提供技术参考.     

利用显著图构建注意力深度网络检测诱虫板蔬菜害虫

为提高诱虫板图像蔬菜害虫检测精度,针对背景区域容易导致误检的问题基于显著图分析技术构建了一种注意力深度网络害虫智能视觉检测方法。首先通过显著图筛选出粗候选区域;然后在粗候选区域内用全卷积神经网络精选出细候选区域;接着用神经网络分类器识别细候选区域害虫种类,得到含有冗余的若干检测框;最后用改进的非极大值抑制消除冗余检测框,实现诱虫板图像中目标害虫的检测。针对小菜蛾和瓜实蝇展开试验,获得86.4%的平均精度均值和0.111只的平均绝对计数误差均值,所提方法平均精度均值比Faster R-CNN和YOLOv4分别高2.74和1.56个百分点,平均绝对计数误差均值比Faster R-CNN和YOLOv4分别低0.006和0.003只;同时,消融试验中移除显著图注意力模块后平均精度均值下降了4个百分点、平均绝对计数误差均值增加了0.207只。试验结果表明,所提方法有效提高了诱虫板图像蔬菜害虫检测精度,其中,引入显著图注意力模块对提升检测精度有重要作用。     

基于GIS的苹果病虫害管理信息系统

以实现苹果病虫害的高效管理与预测预报为目的，设计开发了基于GIS的苹果病虫害管理信息系统。系统以GIS技术、人工神经网络技术和Internet 技术为支撑，包括苹果病虫害基础数据处理子系统、苹果虫害预测预报子系统和苹果病虫害网络发布子系统。在基础数据处理子系统中，系统具有数据获取、数据导出、属性查询、空间查询、数据统计分析、图层编辑、插值分析等功能；在苹果虫害预测预报子系统中，系统具有病虫害图片库维护、病虫害诊断、虫害预测预报功能；在病虫害网络发布系统中，系统提供了苹果病害信息查询、苹果虫害信息查询、专题图查询、预测预报结果查询等功能；系统提供的算法可以较好地预测苹果病害的发生程度。系统作为一种工具软件可以为果树病虫害管理、田间数据分析与精细农业研究提供支持。     

基于DSSAT模型的氮肥管理下华北地区冬小麦产量差的模拟

为了评价氮肥管理对华北地区冬小麦产量差的影响,利用大田试验数据和田间调查的方法,应用DSSAT模型分析了吴桥不同氮肥水平下冬小麦多年平均可获得产量及产量差,并研究了不同地块产量差和氮肥农学效率差的分布。结果表明,不同地块冬小麦产量差异显著,但产量变异较小,地块间施肥水平存在明显差异,且变异较大。模型分析确定222 kg/hm2为最佳施氮肥量,对应的最大可获得产量为7618 kg/hm2,地块产量与最大可获得产量有较大差距,当地冬小麦产量具有一定的提升空间。75%的农户地块的施氮量高于最佳施氮量,且氮肥农学效率普遍偏低。因此,生产中应优化氮肥管理方案,适当减氮并调整施肥时期和改进技术,提高氮肥农学效率,以实现冬小麦生产高产高效。在保障国家粮食安全和保护自然环境双重压力的背景下,通过合理的氮肥管理来缩减冬小麦产量差对提高中国粮食总产及保持农业可持续发展具有重要的意义。     

化学药物杀虫除草的危害与生态学方法控制

本文分析了化学药物对杀虫除草的作用及其对生物与人类造成的危害以及污染大气、水体、土壤和景观所带来的恶果，指出应当积极广泛地开展生物防治，利用害虫天敌、昆虫性引诱剂、雄性绝育等生态学方法有效地控制害虫与野草。同时修订现行的环境管理制度，严格管理食品和药物。     

Long-term organic farming fosters below and aboveground biota: Implications for soil quality, biological control and productivity

Organic farming may contribute substantially to future agricultural production worldwide by improving soil quality and pest control, thereby reducing environmental impacts of conventional farming. We investigated in a comprehensive way soil chemical, as well as below and aboveground biological parameters of two organic and two conventional wheat farming systems that primarily differed in fertilization and weed management strategies. Contrast analyses identified management related differences between “herbicide-free” bioorganic (BIOORG) and biodynamic (BIODYN) systems and conventional systems with (CONFYM) or without manure (CONMIN) and herbicide application within a long-term agricultural experiment (DOK trial, Switzerland). Soil carbon content was significantly higher in systems receiving farmyard manure and concomitantly microbial biomass (fungi and bacteria) was increased. Microbial activity parameters, such as microbial basal respiration and nitrogen mineralization, showed an opposite pattern, suggesting that soil carbon in the conventional system (CONFYM) was more easily accessible to microorganisms than in organic systems. Bacterivorous nematodes and earthworms were most abundant in systems that received farmyard manure, which is in line with the responses of their potential food sources (microbes and organic matter). Mineral fertilizer application detrimentally affected enchytraeids and Diptera larvae, whereas aphids benefited. Spider abundance was favoured by organic management, most likely a response to increased prey availability from the belowground subsystem or increased weed coverage. In contrast to most soil-based, bottom-up controlled interactions, the twofold higher abundance of this generalist predator group in organic systems likely contributed to the significantly lower abundance of aboveground herbivore pests (aphids) in these systems. Long-term organic farming and the application of farmyard manure promoted soil quality, microbial biomass and fostered natural enemies and ecosystem engineers, suggesting enhanced nutrient cycling and pest control. Mineral fertilizers and herbicide application, in contrast, affected the potential for top-down control of aboveground pests negatively and reduced the organic carbon levels. Our study indicates that the use of synthetic fertilizers and herbicide application changes interactions within and between below and aboveground components, ultimately promoting negative environmental impacts of agriculture by reducing internal biological cycles and pest control. On the contrary, organic farming fosters microbial and faunal decomposers and this propagates into the aboveground system via generalist predators thereby increasing conservation biological control. However, grain and straw yields were 23% higher in systems receiving mineral fertilizers and herbicides reflecting the trade-off between productivity and environmental responsibility.     

以病虫害控制为中心的农业生态景观建设

化学农药控制农田病虫害面临诸如农药残留、环境污染等问题,而生物农药及生物防治存在着药效缓慢、成本高、防治对象单一等不足,目前缺乏综合、效果明显、环境友好的农田病虫害控制手段。景观生态学研究显示,致病菌、害虫及其天敌种群受到大尺度上景观格局的影响,从而为病虫害控制提供了一条新的途径:通过合理规划农业生态景观格局,在景观尺度上合理安排种植结构和农事活动,从而控制农田病虫害。本文从景观、田块、耕种管理措施3个层次上论述通过农业生态景观建设控制农业病虫害。景观上:应提高半自然生境的面积比例;丰富半自然生境类型和农田生境作物类型;同时注意景观结构异质性的营建;关注景观连接度,使其保持在既有利于天敌昆虫的迁移、又能较好地阻止病虫害传播的水平上;同时还应提升半自然生境斑块的质量。田块上:通过保留原有的农田边界和新建农田植被缓冲带来控制相邻农田中的病虫害;农田缓冲带的建设要与原有的半自然生境及农田边界构成一个整体,建设过程中主要关注植被的搭配,后期要特别注意杂草、割草、施肥、喷药等管理措施。耕种管理措施上:通过景观层次上合理安排间套混作控制农田中的病虫害,同时注重与农林间作,稻田养鱼养鸭等技术体系和休耕、深耕、保护性耕作、有机肥施用等技术措施相结合。最后以哈尼梯田为例,说明整合以上3个层次可构建综合控制病虫害的农业生态景观。     

温室作物生态健康智能监护系统(GH-Healthex)的研制与测试

研制温室作物生态健康智能监护系统是为了解决目前温室环境监控系统普遍存在的自动获取的数据未与具体作物健康生育的特殊需求相结合，也未被用于病虫害的智能化防治等问题。该文报导的温室作物生态健康智能监护系统(GH-Healthex)实现了这类数据在植物健康监护和病虫害智能化防治中的利用。以番茄为研究案例，系统通过对温室环境监测数据的分析，结合作物种植知识库中番茄生长发育及其病虫害发生规律可以进行智能化决策，即当温室内出现了不利于作物生长的气象条件时，系统会自动的通过系统界面提示用户采取相应措施，以保证温室番茄的优质、高效生产。该系统提供了一个作物知识库平台，若以其他作物的种植和病虫害防治数据替代番茄数据，便能更广泛地推广应用。     

Organically grown Brassica napus – use of border strips and Trichoderma

Oilseed rape (Brassica napus L.) is a very difficult crop to cultivate organically. Only few organic methods are effective in reducing damage from insects and diseases. The current investigation assessed the use of the beneficial ascomycete Trichoderma asperellum (Samuels, Lieckf & Nirenberg) and a trap crop of Brassica rapa L. turnip rape cv. “Brachina,” both with and without an application of slurry fertilizer, for pest suppression and yield enhancement of winter oilseed rape cv. “Californium.” The presence of the trap crop significantly increased 1000 grain weight but not total yield or lipid content of the oilseed rape because turnip rape was not attractive enough to prevent colonization of the principal crop. Increase in 1000 grain weight, lipid content, and total seed yield were found in oilseed rape sprayed with three applications of T. asperellum, but the ascomycete had no influence on the insect pests observed. The effects of the fertilizer are about equal to the effects of the fungus on 1000 grain weight and on lipid content.     

Forest application of the insecticide fenitrothion and its effect on wild bee pollinators (Hymenoptera: Apoidea) of lowbush blueberries (Vaccinium SPP.) in Southern New Brunswick,Canada

Fenitrothion, an organophosphorus insecticide, has been used as a larvicidal spray against spruce budworm (Choristoneura fumiferana (Clem.) Lepidoptera: Tortricidae) over wide areas of forest in New Brunswick, Canada, since 1969. The important pollinators of lowbush blueberries in the region are native wild bees. Populations of these insects appear to have been severely reduced on fields within areas adjacent to where Fenitrothion has been used and residues have been found in carcasses of both honey bees and native bees. From that evidence, together with high toxicity of Fenitrothion to bees, and the area covered by their foraging ranges, it is concluded that blueberry fields and their immediate surrounds received doses of the pesticide. Because blueberries require outcrossing by bees, it is believed that crop failures have, in part, been caused by drifts or indiscriminate applications, or both, of the pesticide.     

滇东南南瓜传粉昆虫密度对生境丧失的差异性响应

响应多样性理论认为不同传粉蜂对环境胁迫的响应尺度和过程在时空上存在差异,然而目前尚不清楚我国重要农林生态系统传粉蜂对环境胁迫的响应规律。试验以云南省文山州广南县南瓜农田生态系统为研究对象,根据农田景观中自然半自然生境数量和面积的变化梯度和离自然半自然生境的距离梯度选择南瓜样地,抽样调查南瓜样地内熊蜂密度和蜜蜂密度。解译卫星影像获取土地类型数据,分析熊蜂密度和蜜蜂密度同自然半自然生境面积百分率和耕地面积百分率的相关系数,在最大相关系数对应的空间尺度下探索蜜蜂密度和熊蜂密度对生境丧失的响应规律。研究发现,熊蜂密度随自然半自然生境面积百分率的增加而显著增加,但蜜蜂密度并不受自然半自然生境面积的影响。同时,熊蜂密度随耕地面积百分率的增加而显著下降,但蜜蜂密度不受耕地面积的影响。此外,熊蜂密度随离自然半自然生境的距离增加而显著下降,但蜜蜂密度不受距离作用的影响。由此可见,云南省文山州南瓜传粉熊蜂和蜜蜂多度对生境丧失表现出多样的响应规律。熊蜂和蜜蜂对生境丧失的差异性响应可能是保障该区域南瓜受粉的重要机制。     

Herbivore and pollinator responses to grassland management intensity along experimental changes in plant species richness

Agricultural intensification is a major driver of global environmental change. Disentangling the relative impact of losses in plant species richness and intensified management on higher trophic level organisms is important for conservation recommendations.We established different management regimes along an experimental gradient of plant species richness within “The Jena-Experiment” in Germany and quantified herbivory as well as grasshoppers and pollinators. Herbivory, grasshopper density and species richness and frequency of flower visiting pollinators were recorded two times in each of four subplots of altogether 80 plots differing in plant species richness. Each of the four subplots was subject to four different levels of fertilizer application and mowing to simulate very low, low, high and very high land use intensity.Fertilization and mowing significantly affected plant–herbivore interactions but plant species richness had no discernible effect. Grasshoppers were most abundant at high intensity subplots (3.1 individuals per m²) and least abundant on very low intensity subplots (1.3 individuals per m²). Leaf damage caused by herbivores was highest in even the very high intensity subplots (3.7%) with four mowing events per year and high amounts of fertilizer application and lowest on subplots with a low management intensity (2.4%) comprising two mowing events per year but no fertilizer application. In contrast, pollinators benefited most from lower management intensities, with only one or two mowing events and no fertilizer addition. In addition, higher numbers of flowering plant species and increased blossom cover was associated with enhanced pollinator species richness and flower visitation.Our results indicate that even in grasslands with high plant species richness, mowing and fertilization are more important drivers of herbivory and flower visitation by pollinators. Management with no more than two cuts per year and without fertilizer application in our grasslands balanced the ecosystem functions of increased pollination and decreased herbivory.     

提高防治棉花害虫效果的施药新技术方案

针对棉花不同生育期和害虫的发生及危害特点，提出了棉花全程动态施药的策略和技术方案，从而提高了农药的有效利用率和防治效果。经由手动喷雾器和机动喷雾机为核心组成的两套技术方案实验测定，表明其在防治棉花害虫，特别是防治棉铃虫方面，有较好的效果。     

Field evaluation of nitrogen fixation and use of nitrogen fertilizer by sorghum/pigeonpea intercropping on an Alfisol in the Indian semi-arid tropics

A field experiment was conducted to obtain the N balance sheet for sole crops and intercrops of sorghum [Sorghum bicolor (L.) Moench] and pigeonpeas [Cajanus cajan (L.) Millsp.]. Intercropping gave a significant advantage over sole cropping in terms of dry matter production and grain yield, as calculated on the basis of the land equivalent ratio and area-time equivalent ratio. The N fertilizer use efficiency and atmospheric N₂ fixation by pigeonpea were estimated using ¹⁵N-labeling and natural abundance methods. The N fertilizer use efficiency of sorghum was unaltered by the cropping system, while that of the pigeonpea was greatly reduced by intercropping. Although intercropping increased the fractional contribution of fixed N to the pigeonpeas, no significant difference was observed between the cropping systems in total symbiotically fixed N. There was no evidence of a significant transfer of N from the pigeonpea to the sorghum. This study showed that use of soil N and fertilizer N by pigeonpeas was almost the same as that by sorghum in sole cropping, indicating the potential competence of pigeonpeas to exploit soil N. However, when N was exhausted by a companion crop in intercropping, the pigeonpea crop increased its dependency on atmospheric N₂ fixation. We conclude that knowledge of how N from different sources is shared by companion crops is a prerequisite to establishing strategies to increase N use, and consequently land productivity, in intercropping systems.     

Effects of NPK fertilizer combinations on yield and nitrogen balance in sorghum or pigeonpea on a vertisol in the semi-arid tropics

A long-term experiment was carried out on a Vertisol from 1986 to 1992 to examine the combined effects of NPK fertilizers on yield using sorghum (Sorghum bicolor L. Moench cv. CSH 5) and short-duration pigeonpea (Cajanus cajan L. Millsp. cv. ICPL 87). The fertilizer treatments were as follows: 0 (no fertilization), N (150 kg N ha^-1 ), P (65.5 kg P₂O₅ ha^-1), K (124.5 kg K₂O ha^-1), and all possible combinations (NP, NK, PK, and NPK). In this study we continued this experiment during the period 1993 to 1994 and analyzed the crop yield response to fertilizers and the N balance. The amount of N derived from the atmosphere and fertilizer was estimated by the ¹⁵N natural abundance method and ^l5N isotope dilution method, respectively. A combined application of Nand P fertilizers gave the highest grain yield for the two crops under the 8th and 9th continuous croppings, unlike the application of K fertilizer. The values of total N for the two crops were significantly higher in the NP and NPK plots. These crops took up N mainly from soil. There was a significant positive relationship between the uptake of N_dff and N_dfs by each crop. Pigeonpea or sorghum took up more N from the soil in the N fertilizer plots than in the plots without N, suggesting that soil N fertility was enhanced and the amount of N supplied from soil increased in the plots with consecutive application of N fertilizer for 7 y. Even pigeonpea, which fixes atmospheric N inherently, needed N fertilizer to achieve high grain yield, suggesting that N fixation by the nodules was not always sufficient to meet the N requirements of the crop under these conditions. Although fertilizer N exerted a beneficial effect on plant growth and yield in the two crops, the values of fertilizer N recovery (FNR) by the two crops were considerably low. Therefore, it is suggested that the development of N fertilizer management which could maximize FNR of each crop should be promoted.     

多因子空间插值模型在农作物病虫害监测预警系统中的构建及应用

农作物病虫害监测预警系统中，监测站点数量一般较少，监测的数据非常有限。因此，利用有限的病虫害监测数据，展现病虫害的整体空间分布情况及其时空变化，迫切需要建立符合病虫害发展规律的空间插值模型。该文在结合各类空间插值算法优点的基础上，考虑农作物病虫害空间插值的特殊性，提出了基于空间方位关系、拓扑关系、距离关系以及自然气候条件影响的多因子插值模型。在广东省各县区分布图的基础上，利用空间方位关系、拓扑关系、距离关系等三类最基本的空间关系，确定各县区的空间相互影响因子，并将各种自然气候条件，如：气温、气候、风向、风速等纳入到影响因子中，构建插值模型，然后在已有部分县区测报站的病虫害数据的基础上，利用插值模型内插出其他县区的病虫害数据，展示病虫害对周围环境的影响，以及病虫情的传递速度，实现病虫害的监测预警。