The simplification of traditional vineyard based agroforests in northwestern Portugal: some ecological implications

In northwestern Portugal, peasants have developed complex vineyard (Vitis vinifera) systems comprising agroforests composed of host trees, vines, annual crops and in some cases animals. Until recently these vineyards suffered very few pest problems and received relatively low pesticide loads. In the last few years, new policy and market forces have prompted the conversion of many of these systems to monoculture thereby decreasing the biodiversity inherent to traditional vineyards. Many scientists are concerned that with accelerating rates of vineyard simplification insect pest and disease problems may increase due to lack of habitat and resources for natural enemies or to a concentration of preferred host plants for specific pathogens and herbivores. During the growing seasons of 1997 and 1999 we conducted several farm surveys of traditional agroforestry and modernized, monoculture farms. We conducted field measurements to elucidate trends in insect pest and disease incidence in both types of vineyards. Our surveys revealed that monoculture vineyards exhibited lower number of species of predators and parasites and correspondingly higher densities of two grape herbivores (Lobesia botrana and Empoasca vitis) than diverse vineyard agroforests. Botrytis bunch rot seemed more prevalent in the monoculture systems, which also received increased fungicide applications when compared to the traditional vineyards. Although preliminary, our studies suggest that new vineyard designs may be more productive, but such gains occur at the expense of biodiversity and agricultural sustainability, reflected on higher pest vulnerability. Further agroecological studies are needed to account for the full ecological costs of the modernization of traditional vineyard agroforests.This revised version was published online in November 2005 with corrections to the Cover Date.     

Insect pest problems in tropical agroforestry systems: Contributory factors and strategies for management

Agroforestry trees are attacked by a wide spectrum of insects at all stages of their growth just like other annual and perennial crops. Pest management in agroforestry has not received much attention so far, but recent emphasis on producing high value tree products in agroforestry and using improved germplasm in traditional systems, and emergence of serious pest problems in some promising agroforestry systems have increased awareness on risks posed by pests. Insects may attack one or more species within a system and across systems in the landscape, so pest management strategies should depend on the nature of the insect and magnitude of its damage. Although greater plant diversity in agroforestry is expected to increase beneficial arthropods, diversity by itself may not reduce pests. Introduction of tree germplasm from a narrow genetic base and intensive use of trees may lead to pest outbreaks. In simultaneous agroforestry systems, a number of factors governing tree—crop—environment interactions, such as diversity of plant species, host range of the pests, microclimate, spatial arrangement and tree management modify pest infestations by affecting populations of both herbivores and natural enemies. Trees also affect pest infestations by acting as barriers to movement of insects, masking the odours emitted by other components of the system and sheltering herbivores and natural enemies. In sequential agroforestry systems, it is mostly the soil-borne and diapausing insects that cause and perpetuate damage to the common hosts in tree—crop rotations over seasons or years. An integrated approach combining host-plant resistance to pests, exploiting alternative tree species, measures that prevent pest build up but favour natural enemies and biological control is suggested for managing pests in agroforestry. Species substitution to avoid pests is feasible only if trees are grown for ecological services such as soil conservation and low value products such as fuelwood, but not for trees yielding specific and high value products. For exploiting biological control as a potent, low cost and environmentally safe tool for pest management in agroforestry, research should focus on understanding the influence of ecological and management factors on the dynamics of insect pest-natural enemy populations. Scientists and policy makers in national and international institutions, and donors are urged to pay more attention to pest problems in agroforestry to harness the potential benefits of agroforestry.This revised version was published online in November 2005 with corrections to the Cover Date.     

A push–pull strategy to control aphids combines intercropping with semiochemical releases

Even if insect pest populations can be reduced by increasing plant diversity through intercropping, natural enemies are not always favored in such systems. Alternatively, semiochemical substances have been tested to enhance biological control, with inconsistent results. Combining both strategies can be an interesting way to maximize pest control. In this work, a 2-year setup involving wheat–pea strip intercropping combined with the release of E-β-farnesene (EBF) or methyl salicylate (MeSA) was tested as a push–pull strategy to simultaneously repel aphids and attract beneficials. Two types of slow-release formulation (i.e., oil and alginate beads) containing EBF or MeSA were deployed with the intercropping. The abundance of aphids was significantly decreased, while hoverfly larvae and mummified aphids increased on both pea plants and wheat tillers by the release of oil-formulated EBF and MeSA. The proportion parasitism of the aphid-parasitism rate [mummies/(aphids + mummies)] was also increased by treating both crops in both years. Releasing EBF through oil rather than alginate beads proved significantly better for attracting natural enemies and reducing aphids. Aphids were negatively correlated with the density of hoverflies (both adults and larvae) and numbers of mummies. All these results showed that combining intercropping with the release of EBF or MeSA formulated in oil can significantly reduce aphid density and attract their natural enemies. Therefore, the combination of both strategies could help farmers reduce the use of insecticides.     

Pests and diseases in agroforestry systems of the humid tropics

Few studies have included detailed investigations of the interactions of agroforestry techniques with pests and diseases, although the relevance of such interactions has long been recognized. The objectives of this review are to provide basic information on pests and diseases in tropical agroforestry systems and to develop concepts which can assist in the future in the systematic data collection and analysis in this field. The emphasis is on simultaneous agroforestry systems with annual and perennial crops, although rotational systems are also discussed. Crop rotation is an important pest and disease control strategy in annual cropping systems, and the principle of altering host with non-host plants can also be applied in improved fallow systems, provided that hosts of crop pests and diseases are avoided when selecting the fallow species. When annual cropping systems are transformed into simultaneous agroforestry, the control strategy of frequent disturbance of pest and disease populations is to some extent substituted for the strategy of increased stability and internal control mechanisms. However, reduced pest and disease risk is not automatically achieved by introducing perennial plants and increasing the plant diversity in a system. If plant species are introduced that harbor pests or diseases of other species in the system, the risk of pest and disease outbreaks may actually increase. For evaluating such risks, it is important to consider host-ranges of diseases on the pathovar instead of the species level. Beside the selection of compatible plant species, their spatial arrangement may be important for reducing the spread of pest and disease organisms through the system, although little information is available on such effects, and they may be largely irrelevant for organisms with efficient dispersal mechanisms such as wind-dispersed fungi. In addition to the species-specific, biological effects of plants on pests and diseases, their unspecific, physical effects can be of major relevance for pest and disease development as well as the susceptibility of the affected plant species. Increased pest and disease incidence has often been observed directly at the tree-crop interface, caused by the humid microclimate, physical protection of mammal and bird pests by the trees and eventually reduced pest and disease tolerance of competition-stressed crops. Linear tree plantings and hedgerows affect the wind transport of small insects and disease propagules, the active immigration and emigration of pest organisms as well as the populations of natural enemies. Similarly, overhead shade has a major effect on the micro-climatic conditions under which pest and disease organisms, their natural enemies and the crops themselves develop, and its optimization is a highly efficient control strategy for many pests and diseases. On infertile soils, the susceptibility of crops to pests and diseases is strongly affected by the availability of plant nutrients, which may be influenced by agroforestry techniques in various ways. Soil management measures such as mulching and planting cover crops may affect crop health by improving soil fertility and by directly acting on pest and disease populations. The importance of a more systematic collection of pest and disease related information for agroforestry, e.g., in a central database, and of the development of strategies for reducing pest and disease risks in agroforestry in cooperation with farmers is stressed.This revised version was published online in November 2005 with corrections to the Cover Date.     

人工林物种多样性与害虫的控制

根据国内外的最新研究成果,从人工林害虫可持续控制的需求出发,对利用物种多样性与系统稳定性控制虫害的可能性、人工林物种多样性与害虫控制的关系及其内在作用机制、天然林与人工林在抑制虫害能力上的差别进行综述,分析人工林植物物种多样性与昆虫物种多样性对害虫控制的影响,认为植物物种多样性主要从植食性昆虫搜寻寄主植物,植物营养的差异对植食性昆虫取食和发育的影响,及种类组成不同的植物群落中植食性昆虫天敌数量的变化3个方面影响害虫的发生;要通过调节植物群落中昆虫物种的多样性影响目标害虫的种群数量,既要维护其天敌类群的稳定,也要使与害虫处于同一营养层次的其他植食性昆虫有足够的多样性,甚至也要保护和利用中性、中位及顶位昆虫.对人工林害虫的控制,可借鉴天然林自控虫害的原理,采用生态育林、封山育林及生物技术措施,逐步调整林分的结构,提高其物种多样性,增强林分自身的抗虫能力.     

Defining competition vectors in a temperate alley cropping system in the midwestern USA: 4. The economic return of ecological knowledge

We tested the economic value of ecological knowledge in a midwestern USA alley-cropping system where row crops are planted in alleys between fine hardwood trees grown for veneer. Economic models were constructed to compare among agroforestry designs as well as to compare agroforestry with traditional forest plantation culture and row crop monoculture and rotational management. The general modeling approach was to quantify production inputs and outputs, estimate costs and revenues, simulate tree growth and crop productivity in agroforestry configurations, and estimate discounted cash flows. We incorporated scenarios that controlled both above- and below-ground competition through appropriate management as found in our previous research. This research showed the importance of below-ground competition in determining crop yields and the period of time that crop income could be expected from the agroforestry interplanting. Net present values and internal rates of return showed that agroforestry systems were generally more favorable investments than traditional agriculture and forestry. More importantly, the use of simple management techniques targeted at reducing below-ground competition allowed longer cultivation of row crops, greatly increasing returns to the landowner. Thus, the economic benefit of understanding the ecological interactions within agroforestry plantings dictates that accurate assessment of agroforestry alternatives will require the modeling of agroforestry as an integrated, interactive system.This revised version was published online in November 2005 with corrections to the Cover Date.     

An equation for the replacement value of agroforestry

This article examines some of the existing analytical tools which quantify both the ecological and economic aspects of intercropping decisions. The characteristics of tree crops are evaluated to determine how a specific tool, the replacement value of intercropping (RVI), could be modified to better interpret agroforestry improvements to bush fallow farming systems. The modified equation captures some of the potential production improvements associated with agroforestry by accounting for the fraction of time that a field is actually in production over the long run. The result is an improved estimate of the average annual difference between a tree/crop polyculture and a monoculture system which employs fallows.     

人工林害虫“精确防治”技术体系的研究

人工林的虫害问题将是长期的客观存在，促进人工林生态丰度的提高与经济可行是建立有效的防治技术体系必须遵守的2个基本前提。文中提出了人工林害虫“精确防治”的概念，阐述了实施“精确防治”的林业科学基础，建立了从造林(林分改造)设计到化学农药精确闪击初步完整的技术体系。     

森林植物群落多样性与虫害自然控制力的研究进展

讨论了森林植物群落多样性与森林虫害自然控制力间的关系,阐明了森林虫害自然控制力有随森林植物群落多样性的升高而增强的趋势.并认为森林虫害自然控制力的本质是森林植物群落多样性的生态系统功能.初步提出了通过合理地提高森林植物群落多样性来提高森林虫害自然控制力的主张及提高森林虫害自然控制力的几种具体途径,即合理的乔木物种混交;引进和保留乡土的草本、灌木物种;提高生态系统水平的生物多样性;避免营造大面积的人工纯林.     

浅谈城市林业有害生物治理对策

创建森林城市,保护城市生态环境,已成为许多城市可持续发展的理念之一。而随着城市绿地的大量增加,日益严重的城市林业有害生物是人们不得不重视的重要工作。笔者以丰城市城区林业有害生物防治工作为分析背景,提出了城市林业有害生物发生特性和进行综合治理的对策。     

First record of the invasive pest <Emphasis Type="Italic">Drosophila suzukii</Emphasis> in Ukraine indicates multiple sources of invasion

Drosophila suzukii, commonly known as the spotted-wing Drosophila, is an invasive polyphagous fruit pest, which has emerged as a global threat to agriculture in the Americas and in Europe. Due to the rapid spread, great economic losses and its pest behavior, D. suzukii represents a powerful model for invasion biology and pest management studies. However, its current European distribution, invasion routes and levels of genetic diversity in populations of D. suzukii are poorly understood. We present the first report of D. suzukii from Ukraine, with the invasion likely occurring close to 2014. The pattern of genetic variation at cytochrome oxidase I among D. suzukii populations from Europe, USA and Asia reveals comparatively high genetic diversity in the Ukrainian population of this pest species, suggesting a complex invasion scenario from multiple sources. Further monitoring patterns of genetic variation across space and time, to better understand the invasion routes of this invasive insect pest, will be an essential part for developing successful pest management strategies.     

对建立豫北林业有害生物天敌繁育基地可行性的探讨

在豫北地区建立一座林业有害生物天敌繁育基地,实施人工繁育,释放天敌昆虫进行生物防治,可有效地控制林业有害生物和多种农业害虫的危害,预防外来林业有害生物传入,保护林业资源和生态环境。通过对建立林业有害生物天敌繁育基地的充分探讨和论证,认为该项目的实施是非常必要和可行的。     

Drugs from bugs: the use of insects as a valuable source of transgenes with potential in modern plant protection strategies

Transgenic expression of antimicrobial peptides in crops has become a novel approach among the strategies to combat phytopathogens in modern plant protection measures. The first antimicrobial transgenes of insect origin, modified cecropins, have been demonstrated to confer resistance of several transgenic cultivars against both bacterial and fungal phytopathogens. Insects represent a promising reservoir for antimicrobial peptides to engineer disease resistant crops. The increasing knowledge about the potent insect innate immunity may help to develop a novel strategy in sustainable agriculture. Several approaches are presently under investigation to prevent evolution of phytopathogens that can overcome disease resistance in transgenic crops expressing an insect antimicrobial peptide. Pathogen-induced expression of insect antimicrobial peptides in crops and combined multiple expression of different antimicrobial peptides along with proteinase inhibitors from insects may prevent selection of resistant phytopathogens. The potential of insect antimicrobial peptides as transgenes to render disease resistant crops has just started to be explored and may provide tools to be ahead of the evolutionary adaptability of phytopathogens.     

宁夏银北二代林网主要害虫空间格局及其应用

通过聚集指标法对宁夏银北地区二代林网中主要发生的枝梢害虫，光肩星天牛幼虫，木蠹蛾幼虫三类害虫进行测定，得知该三类害虫均呈聚集分布。通过Ｍ－Ｘ回归法，确定出理论抽样数和量大抽样量公式。并列出了天牛序贯抽样分析表。     

Crop diversity increases predator abundance but not predation on cereal leaf beetles in agricultural landscapes

The indirect effect of seminatural habitats on pest suppression has been widely studied in agricultural landscapes. By contrast, the role of crop diversity on pest suppression by predators has seldom been explored, particularly using molecular gut-content analysis (MGCA). In addition, differences between early- and late-season effects of landscape complexity on pest control, crucial to ensure season-long control, have received little attention. During 2014 and 2015, we investigated the effect of agricultural landscape complexity and crop diversity on cereal leaf beetle (CLB, Oulema melanoplus) predation early in the season using sentinel egg cards and late in the season by assessing larval predation using MGCA. Early-season CLB egg predation and late-season abundance of Nabis americoferus and coccinellids in wheat fields were positively correlated with amount of woodland habitat in these landscapes. Contrary to our predictions, crop diversity had negative associations with the late-season frequency of larval predation and the abundance of N. americoferus. Predator diversity and the abundance of Hippodamia lady beetles had negative associations with CLB abundance, highlighting the significant contribution of some generalist predators to CLB suppression. Our results suggest that the proportion of woodland and a few major crops (e.g., canola and non-cereal crops), rather than crop diversity, are associated with higher predation at different temporal scales. Overall, our results suggest that a habitat management strategy could be implemented to adjust the crop rotation regime to add the right kind of crop diversity in the landscape to support the natural control of CLB.

     

Transgenic overexpression of P450 genes confers deltamethrin resistance in the fall armyworm,Spodoptera frugiperda

Journal of Pest Science - The fall armyworm (FAW), Spodoptera frugiperda, is a polyphagous insect pest feeding on many host plants, including some major crops such as corn and rice. This pest has...     

Influences of trees on abundance of natural enemies of insect pests: a review

In this article we review the use of natural enemies in crop pest management and describe research needed to better meet information needs for practical applications. Endemic natural enemies (predators and parasites) offer a potential but understudied approach to controlling insect pests in agricultural systems. With the current high interest in environmental stewardship, such an approach has special appeal as a method to reduce the need for pesticides while maintaining agricultural profitability. Habitat for sustaining populations of natural enemies occurs primarily at field edges where crops and edge vegetation meet. Conservation and enhancement of natural enemies might include manipulation of plant species and plant arrangement, particularly at these edges; and consideration of optimum field sizes, number of edges, and management practices in and near edges. Blending the benefits of agricultural and forestry (windbreak) systems is one promising approach to field edge management that has additional benefits of wind protection and conservation of desirable wildlife species.Journal series 10549 of the Agriculture Research Division, University of Nebraska-Lincoln. This material was prepared with the support of USDA Agreement 91-COOP-1-6592 for the USDA/EPA Program, Agriculture in Concert with the Environment. Any opinions, findings, conclusions or recommendations expressed herein do not necessarily reflect the views of the US Department of Agriculture or the US Environmental Protection Agency.     

Effects of tree diversity on insect herbivory

Tree diversity has long been considered a key driver of insect herbivory in forest ecosystems. However, studies have given contradictory results: increased tree...     

A review of the major biological approaches to control the worldwide pest Tetranychus urticae (Acari: Tetranychidae) with special reference to natural pesticides

The two-spotted spider mite, Tetranychus urticae Koch, is a phytophagous pest that can cause significant yield losses in many agricultural crops, including fruits, cotton, vegetables, and ornamentals. To date, 3877 host species have been reported around the world in both outdoor crops and greenhouses. In this paper, we present the common methods to control this pest including chemical and biological practices. While synthetic acaricides have been widely used to manage T. urticae, in recent years, interest in pesticides derived from plants has increased considerably as a result of environmental concerns and pest population resistance to conventional pesticides. Some botanical pesticides can be easily produced, are relatively efficient against pests, and with few exceptions, their mammalian toxicity and persistence in the environment is low. Thus, the use of plant extracts appears to be a promising alternative strategy for pest management. The present paper reviews studies on the biocidal activities of plant extracts, including essential oils, against T. urticae, a plant-feeding mite found worldwide and a serious agricultural and home garden pest.     

以昆虫为指示物种监测和评价森林生态系统健康初探

森林生态系统健康是保证生态系统服务功能的前提, 森林生态系统健康评价方法及指标体系已成为森林生态系统健康研究的核心内容。昆虫是森林生物多样性的重要组成部分, 在森林生态系统主体群落中, 昆虫与植物密切关联。森林害虫胁迫及昆虫多样性变动, 对于评估森林生态系统健康状况具有重要价值。研究显示, 昆虫多样性可应用于对森林生态系统健康的快速评估。