Modelling the establishment,spread and distribution shifts of pests

Abstract

During the last century increasing human trade networks have interacted with other global changes – such as land use and climate change – to accelerate the range expansion of pest species worldwide. In this special issue, we present a series of articles that model the risk of establishment and spread of non-native harmful species, as well as shifts in the distribution of native pest species. We also provide a state-of the art review of the available literature on species distribution models for pests, weeds, and pathogens. Recent advances in modelling approaches have allowed us to significantly improve our abilities to predict changes in species distribution, and these tools have been widely used to enhance biosecurity planning and pest management. We expect that this special issue contributes toward and integration of the scientific knowledge and the development of novel approaches to model pest species distribution, as well as to better understand the factors that influence their expansion in the context of a rapidly changing world.     

Mutual influence of forests and pastures on the seedbanks in the Eastern Amazon

The objective of this study was to compare the floristic composition and species diversity existing in the seedbanks of forests and pastures. The seedbanks were sampled in three forest and three pastures areas in a community of smallholder farmers, in Pará state, Brazil. Seedling emergence in a glasshouse was used to quantify and identify the seeds. The total densities and diversity of the seedbanks were not significantly different among the pastures and forests, but the floristic composition was different. The herbaceous species predominated in both the pastures and the forests, but in the forest the abundance of shrub and tree was higher than herb. The seed density of several pioneer woody species was higher in the forests and the density of several herbaceous species was greater in the pastures. The influence of the forest species on the pastures and of the pastures species on the forests is a result of the initial process of human occupation and illustrates a dynamic that can lead to both the conservation of forest species and the spread of weed species. Actions should be carried out to avoid disturbance in the forests and improve biodiversity preservation in rural areas.     

Mating system complexity and cryptic speciation in the seed bank pathogen Pyrenophora semeniperda

Mating strategies contributing to a balance between inbreeding and outcrossing are understudied in all but a few model fungal pathogens. This study examined factors that influence the occurrence of the sexual state of Pyrenophora semeniperda. It was consistently found to have functional copies of the MAT1-1 and MAT1-2 idiomorphs essential for sexual reproduction, despite considerable polymorphism in both single nucleotide polymorphisms (SNPs) and number of 18-base minisatellite repeats. The two idiomorphs occurred at approximately equal frequencies across 25 populations on Bromus tectorum seeds in the western United States, suggesting maintenance of sexual reproduction. The putative mating system is described as facultative pseudohomothallism, with only one of the two MAT1 idiomorphs found in a nucleus. Unikaryotic strains of opposite mating type can potentially mate, as can nuclei of opposite mating type in a thallus that results from anastomosis between vegetatively compatible unikaryotic strains. Strains shown to be dikaryotic using simple sequence repeat (SSR) markers may contain either or both MAT1 idiomorphs. Most populations consist of a mixture of MAT1-1, MAT1-2 and MAT1-1/MAT1-2 genotypes. A possible constraint on recombination is the presence of multiple strain groups characterized by ITS haplotype. These are apparently vegetatively incompatible, as even dikaryotic strains are invariably composed of a single ITS haplotype. Different ITS haplotypes also have unique combinations of MAT1-1 and MAT1-2 allelic variants, suggesting that perhaps these strain groups are also sexually incompatible. Phylogenetic analysis using both genome-wide SNP/indel polymorphisms and SSR markers demonstrated genetic divergence among ITS haplotypes, supporting the hypothesis that these strain groups may represent cryptic species.     

森林-草原交错带土壤节肢动物物种相对多度模型拟合研究

应用群落物种多度分布模型:对数级数分布模型、对数正态分布模型、几何级数分布模型和分割线段分布模型研究了森林草原交错带土壤节肢动物群落的种-多度分布关系。结果表明:对数级数分布模型和对数正态分布模型能够较好的拟合交错带大型土壤节肢动物群落的种-多度分布,中小型土壤节肢动物仅能用对数级数分布模型来拟合;几何级数分布模型和分割线段分布模型则不适于描述该区土壤节肢动物群落物种多样性。对数级数分布的参数α和对数正态分布的参数λ是反映群落结构特征内在性质的量,可以作为物种多样性指数运用,能较好地反映群落的物种丰富度。研究结果可为交错区群落物种多样性保护提供理论基础。     

First record of the Q biotype of the sweetpotato whitefly, <Emphasis Type="Italic">Bemisia tabaci</Emphasis>, in Guatemala

Bemisia tabaci (Gennadius) adults and immatures were collected from poinsettia plants at two commercial production greenhouses in Guatemala during an invited tour to observe IPM practices within the facilities. Despite extensive scouting, only low numbers of insects were collected from vegetable, weed and wild ornamentals species located close to these facilities. Prior to molecular and biochemical analyses, whitefly immatures were initially identified as B. tabaci using morphological characters of the pupae to distinguish them from the greenhouse whitefly. The biotype status of adults and immatures was then established using esterase isozyme patterns and MTCO1 sequencing. The Q biotype was the only biotype found on commercially grown poinsettia plants. The previously recorded B biotype was observed outside the greenhouse facilities on Lactuca spp., Hibiscus spp. and Euphorbia spp. (wild poinsettia). The New World biotype was observed on wild poinsettia and field-grown beans (Phaseolus spp.). This is the first report of the Q biotype in Guatemala, and serves notice of the need for greater vigilance in the management of whiteflies on poinsettia mother stock used as a source of cuttings for export to the USA.     

科尔沁沙地沙丘植被发育过程及物种组成变化

以处于流动沙地、半固定沙地、固定沙地等阶段的群落样地为对象 ,研究了沙地植被发育过程群落物种组成的变化。研究结果表明 ,从流动沙地到半固定沙地、再到固定沙地 ,每一阶段对应着典型的群落类型 ,每一群落类型优势种的作用明显。植被发育过程物种丰富度、Shannon Wiener指数、生活型结构和科属组成的变化 ,都表明了植被发育程度的提高和群落生态功能的恢复。禾本科植物在群落中的地位和作用不断上升 ,植被的草原成分增加 ,草地质量改善和提高。     

Chili anthracnose: Colletotrichum taxonomy and pathogenicity

Chili anthracnose is caused by Colletotrichum species mostly associated with the acutatum, truncatum and gloeosporioides complexes. Since 2009 the Colletotrichum taxonomy has been extensively revised based on multigene phylogenetics, which has had a large impact on the number of species known to cause anthracnose disease of chili. This review discusses (i) the taxonomy of Colletotrichum spp. infecting chili, and (ii) the impact of Colletotrichum pathotypes on breeding for resistance to anthracnose. To date, 24 Colletotrichum species have been identified as pathogens of chili anthracnose, with the three main pathogens being C. scovillei, C. truncatum and C. siamense. Identification of several pathotypes within these three Colletotrichum species, particularly pathotypes that can overcome resistance in the related Capsicum species, Ca. chinense and Ca. baccatum, will be of major concern to plant breeders as they develop resistant chili genotypes from the transfer of resistance genes from these Capsicum species into Ca. annuum. Accurate identification of the Colletotrichum species causing anthracnose and improved understanding of the biology of the Colletotrichum species and their interaction with the host will enable the application of improved integrated disease management techniques.     

Effects of grassland management on the community structure,aboveground biomass and stability of a temperate steppe in Inner Mongolia,China

Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass(AGB), biodiversity and community stability associated with different management practices were studied with a three-year field investigation in a temperate steppe of Inner Mongolia, China. The species richness, Shannon-Wiener index, evenness, plant functional type abundance, AGB, temporal community stability, summed covariance, scaling coefficient and dominant species stability were compared among areas subjected to long-term reservation(R), long-term grazing(G), mowing since enclosure in 2008(M) and grazing enclosure since 2008(E). Site R had higher perennial grass abundance and lower species richness than sites G, M and E, although the AGB was not significantly different among the four sites. The species structure varied from a single dominant species at site R to multiple dominant species at sites G, M and E. The long-term reservation grassland had lower biodiversity but higher stability, whereas the enclosed grassland with/without mowing had higher biodiversity but lower stability. Different stability mechanisms, such as the compensatory dynamics, mean-variance scaling and dominant species stability were examined. Results showed that community stability was most closely related to the relative stability of the dominant species, which supports the biomass ratio hypothesis proposed by Grime.     

青海湖流域沙柳河草甸群落结构与数量特征

沿青海湖流域沙柳河河岸,选取多个断面进行样方调查,分析沿沙柳河距河流入湖处不同距离、垂直河岸方向上草甸群落结构、地上生物量以及物种多样性的变化特征,并讨论影响群落结构变化的生境因子。结果表明：① 在所调查的样地中,有草本植物52种,隶属39属,13科。平均总盖度为70%,平均地上生物量为131 g•m^-2。② 随着离湖距离的增加,Shannon-Wiener指数、物种丰富度、物种均匀度指数、地上生物量呈现先增加后略微减小的趋势,盖度的变化趋势是先增加后不变。土壤含水量和土壤含盐量、海拔等可能是影响植物群落空间分布差异的主要原因。③ Shannon-Wiener指数、物种丰富度与地上生物量呈现不明显的线性关系。     

新疆列当种类、危害与防治现状

列当是一种根部全寄生恶性杂草,影响作物生长,对农业生产造成了巨大破坏。目前,列当防治措施主要包括轮作、种植诱捕作物、化学防治等,但尚无适用于大部分地区及作物的有效防治措施。本文综述了新疆列当种类、寄生特点、危害和目前采取的防治措施,并对列当的萌发刺激物、防治机理和化学除草剂在大田应用提出展望,以期为新疆相关防治工作提供参考。     

日本《外来入侵物种法》及对我国外来物种管理立法和科研的启示

日本政府于2004年6月颁布了《外来入侵物种法》,10月环境省制定的《预防外来入侵生物对生态系统造成不利影响的基本政策》通过内阁决议,该法案于2005年6月1日起生效。本文简要介绍了日本外来生物管理有关策略和基本政策,并针对我国现状提出了外来物种管理立法及科研方面的建议:(1)成立国家级外来物种管理委员会及外来物种专家委员会,统筹外来物种管理工作;(2)对现有法律法规体系进行系统评估,加强外来物种管理立法;(3)加强对外来物种的科学研究,特别是加强外来入侵物种环境风险评估系统建设;(4)进一步加强建立国家级、一站式的外来物种数据库和外来物种数据交换所,促进信息交流。     

Allelopathic potential of Trifolium resupinatum L. (Persian clover) and Trifolium alexandrium L. (Berseem clover)

This experiment was conducted in order to determine if Persian clover ( Trifolium resupinatum ) and Berseem clover ( Trifolium alexandrium ) contained water-soluble and methanol-soluble constituents that could affect the seedling growth of four test species; namely, Amaranthus retroflexus , Convolvulus arvensis (field bindweed), Secale cereale , and Sinapis arvensis (wild mustard) . The above-ground tissues of the Persian and Berseem clover plants were collected during the vegetative growth stage and oven-dried. Three concentrations of aqueous and methanolic extracts were used at full-strength (33.3 g L⁻¹), half-strength (16.7 g L⁻¹), and quarter-strength (8.3 g L⁻¹). Distilled water was used as the control. The weed seeds were placed in Petri dishes containing the legume extract or distilled water (control). The seedling growth of the weed species declined with the increasing concentration of the clover extracts. Wild mustard exhibited the highest sensitivity to both the legume extracts. Compared to the aqueous extract, the methanolic extract caused a greater decline in the seedling growth of the weeds. Berseem clover was the stronger inhibitor of the weed seedling growth, as compared to Persian clover. Therefore, the amounts of allelochemicals present might differ in these two clover species. Field bindweed showed the least sensitivity to both the legume extracts. Field bindweed showed more tolerance to the allelochemicals produced by the clover species.     

新疆玛纳斯麻黄生态保护区植物群落特征及其多样性分析

以重要值为测度指标,选择反映群落物种多样性、丰富度和均匀度的7个测定指数,对玛纳斯平原林场麻黄生态保护区植物群落的物种多样性研究。结果表明:在整个研究区荒漠植物群落中,中麻黄、百刺、蛇麻黄和骆驼蓬等物种有较高的重要值,而草本植物的重要值较低;麻黄种群在样地中属优势种,且进一步发展的趋势明显,减少人为干扰,麻黄种群自然恢复较快。     

宁波地区小菜蛾幼虫期和蛹期寄生蜂调查

小菜蛾Plutella xylostella是十字花科蔬菜最重要的世界性害虫,保护和利用寄生性天敌是控制小菜蛾的重要手段。为有效控制小菜蛾在蔬菜上的为害,减少农药用量,作者于2007年4月至2009年1月对宁波地区小菜蛾幼虫期和蛹期主要寄生性天敌种类及其田间自然被寄生率进行了调查。结果表明,宁波地区十字花科蔬菜上小菜蛾幼虫期和蛹期共有8种原寄生蜂（菜蛾盘绒茧蜂Cotesia vestalis、螟蛉盘绒茧蜂Cotesia ruficrus、颈双缘姬蜂Diadromus col-laris、东方长颊姬蜂Macromalon orientale、棉铃虫齿唇姬蜂Campoletis chlorideae、无脊大腿小蜂Brachymeria excarinata、齿唇姬蜂Campoletissp.、弯尾姬蜂Diadegmasp.）、1种兼性寄生蜂（菜蛾啮小蜂Oomyzus sokolowskii）和5种重寄生蜂（盘背菱室姬蜂Mesochorus discitergus、粘虫广肩小蜂Eurytoma verticillata、稻灿金小蜂Trichomalopsis oryzae、绒茧灿金小蜂Trichomalopsis apanteloctena和啮小蜂Tetrastichussp.）,其中优势种为菜蛾啮小蜂和菜蛾盘绒茧蜂,分别占62.23%和31.19%,同时,小菜蛾幼虫期田间自然被寄生率普遍高于蛹期。另外,菜地蔬菜品种的多样性有利于寄生蜂的保护和利用。     

北方农牧交错带生态恢复与重建的原则及对策

对我国北方农牧交错带生态退化的现状和原因进行了分析 ,提出了生态恢复与重建的 5个指导思想与原则 :物种本地化原则、物种多样化及其合理配置原则、保护为主重建为辅的原则、以防为主防治结合的原则和生态与经济相协调的原则 ,并提出了生态恢复与重建策略。     

Influence of obligate parasite Cuscuta campestris on the community of its host Mikania micrantha

As a means of biologically controlling Mikania micrantha in South China, the influence of the native obligate parasite Cuscuta campestris on its natural community was studied in the field. Mikania micrantha is a non‐indigenous vine that smothers other vegetation and has become a major invader of agricultural land and native areas in Southern China. These preliminary results showed pronounced effects on M. micrantha by C. campestris. Cuscuta campestris significantly reduced biomass of M. micrantha, increased species diversity and helped re‐establishment of native species. Biomass of M. micrantha decreased from 328 g m^?2 to 82 g m^?2, biomass of companion species increased from 41 g m^?2 to 145 g m^?2, the total number of species increased from 7 to 19 and the species diversity index from 1.8 to 5.6, when C. campestris was present. These results indicated that the use of C. campestris could be a potentially effective way of controlling M. micrantha and could help us achieve the novel objective of biological control of weeds using weeds.     

番茄枯萎病致病镰刀菌种类鉴定及优势种群的研究

<正>镰刀菌(Fusarium spp.)是真菌的一个重要属,分布极为广泛,是多种重要植物的病原菌。其中,由致病性尖孢镰刀菌(Fusarium oxysporum)侵染引起的植物枯萎病是一种世界性的土传真菌病害。病菌从植物根部侵入,扩展进入维管束,造成植株枯死,在植株的全生育期均可发生,给生产带来了巨大的损失。国内外已报道的被严重为害的作物有棉花、甘蔗、香蕉、番茄、黄瓜、哈密瓜、西瓜、大     

Monetary Valuation Methods for Economic Analysis of the Benefit-Costs of Protecting Rare Wildlife Species from Predators

Many threatened and endangered species are negatively impacted by predation. Management of the predators that are geographically and temporally in position to threaten species of concern can greatly aid in their conservation. However, decisions on management strategies are based within economic constraints, while the success of management actions is measured by wildlife resource improvement. Here, we review methods for applying monetary valuations for threatened and endangered species so that economic analyses of management actions can be used to help guide and evaluate management decisions. A variety of applied examples are provided to demonstrate the principles. This revised version was published online in July 2006 with corrections to the Cover Date.