Genetic structure of the invasive Chromolaena odorata in China

Chromolaena odorata is one of the world's worst tropical weeds, and it can be found in Guangdong, Guangxi, Hainan and Yunnan provinces in China. Genetic variation of 27 C. odorata populations sampled from across its invasive range in China was investigated using inter‐simple sequence repeats (ISSR) analysis. All populations exhibited low levels of genetic variation. On average, 2.35% of the ISSR loci were polymorphic, total genetic diversity (H_T) was 0.0406 and Shannon's information index (H_sp) was 0.0623. High genetic identities (I) between populations (0.9687 ± 0.01204) indicated low genetic differentiation. A frequent founder effect was interpreted as the main cause of the genetic structure observed in C. odorata.     

Multiple introductions are responsible for the disjunct distributions of invasive Parthenium hysterophorus in China: evidence from nuclear and chloroplast DNA

Parthenium hysterophorus is an invasive weed native to tropical and subtropical America. Since its introduction into China in 1926, this weed has been limited to southern areas (18°–25°N). However, new populations were recently reported in Shandong (35°N). The origin of this geographically isolated population remains unclear. In this study, we used inter simple sequence repeat and chloroplast DNA sequence markers ( trnQ-5'rps16 ) to investigate the genetic structure of 18 invading populations of P. hysterophorus and to examine the genetic relationship of Shandong and southern populations. Our data show that Shandong population is genetically different and has apparently higher levels of genetic diversity than most populations in southern China. Both neighbour-joining clustering and principal coordination analysis clearly separated Shandong from other populations. Chloroplast DNA sequence analysis further confirmed that the Shandong population was characterised by a unique haplotype that was not found in southern populations. We conclude that the population in Shandong may have been independently introduced from areas outside China. As P. hysterophorus has a broad potential distribution in China, attention should be paid to both international and domestic quarantine to prevent new introductions and curtail the possible hybridisation and gene flow between populations in different regions.     

Genetic variation and structure in native and invasive Solidago canadensis populations

Solidago canadensis is native to North America, but has become a noxious invasive plant in China. We know only a little about its invasion history and the effects of introductions on its genetic composition. Here, we investigated genetic variation and structure between 15 North American and 13 Chinese populations of S. canadensis using AFLP makers. Four AFLP loci suggested relatively high genetic diversity of this weed and similar genetic variation between the invasive range and the native range. Most genetic variation was within populations across two ranges, but the Chinese range had a higher degree of among‐population variation than the North American range. Multiple tests, including Bayesian assignment, UPGMA analysis, PCoA and analysis of ‘isolation by distance’, showed that the Chinese populations originated from at least two distinct native sources and that secondary introduction or dispersal should be common in China. Also, North American populations were possibly a single genetic group. Overall, S. canadensis in China was probably founded from multiple introductions and then spread through long‐distance dispersal associated with human activities. Genetic variability in the species in the invaded range appears to have favoured establishment and spread and may well provide a challenge to successful control.     

Local spread of the invasive Cyperus esculentus (Cyperaceae) inferred using molecular genetic markers

Over the last 20 years Cyperus esculentus (yellow nutsedge) has become invasive in south‐west France. Because the genetic variation of invasive species can affect the success of management strategies, amplified fragment length polymorphism markers were used to assess the amount and distribution of genetic diversity in this clonally reproducing weed. Population samples of C. esculentus were collected mainly in south‐west France, with 21 samples of C. eragrostis also included in this study. A total of 113 polymorphic loci were identified (50% of the bands scored) in C. esculentus. A low level of genetic diversity (0.140) was detected, of which 95% were partitioned among sites. The regional patterns of variation could have been caused by rapid range expansion of clones propagated by harvesting machinery. Implications of the high clonality detected in C. esculentus are discussed in the context of the development of weed management strategies: because reproduction of the weed in Haute Lande occurs by tubers only, vegetable production should be reduced in infested areas.     

Genetic diversity of Solanum elaeagnifolium,an invasive problematic weed in Jordan

Solanum elaeagnifolium (silverleaf nightshade) is a problematic weed that is common in Jordan and difficult to control. The weed exhibits distinct morphological variations in growth habit, leaf shape, leaf margins, flower colour and presence or absence of spines between individuals among and within populations suggesting genetic differences. Genetic variations among 61 samples of S. elaeagnifolium collected from heavily infested sites in the central Jordan Valley were investigated using six simple sequence repeat (SSR) markers and eight amplified fragment length polymorphism (AFLP) primer combinations. Results showed that 111 out of 675 AFLP bands were polymorphic generating polymorphism information content (PIC) of 38.0%, while 23 SSR polymorphic alleles were detected generating a PIC of 30.8%. Phylogenetic analysis using RaxML software identified four major clades with a clear clustering of the samples with their collection sites. Genetic analysis using both techniques revealed high level of genetic diversity among S. elaeagnifolium samples collected from a small geographical area indicating that a range of genetic diversity may be detected in weed populations across the country that may complicate its management.     

科尔沁沙地外来入侵植物光梗蒺藜草的种子库分布格局

在通辽市科尔沁区的固定沙地,半流动沙地采用相邻样方法观测光梗蒺藜草已萌发种子和未萌发种子在不同埋深中的分布,发现在固定沙地中,光梗蒺藜草种子分布在埋深较浅处(0～3cm),集中分布在0～1cm;在半流动沙地中,光梗蒺藜草种子分布较为分散,在1～15cm埋深处均有分布,在埋深0～5cm处种子数量较多。固定和半流动沙地中光梗蒺藜草种子随着埋深增加出苗率也随之增加,可达到100%。负二项式法和方差/均值比率(分布系数)法一致的验证了光梗蒺藜草苗和土壤种子库的种子种群分布格局为集群分布。光梗蒺藜草自然散布距离很短,是造成其种群集聚分布格局的原因。     

Diversity and differentiation in two populations of Gibberella circinata in South Africa

Gibberella circinata [anamorph Fusarium circinatum (=  F. subglutinans f.sp. pini )] causes pitch canker and is an important pathogen in South African pine nurseries. The initial outbreak of the pitch canker fungus was limited to a single nursery at Ngodwana in Mpumalanga Province. Subsequently, several other pine nurseries in South Africa became infected. Most of these outbreaks were relatively small except for the outbreak in the Klipkraal nursery (Mpumalanga Province). The genetic diversity, population differentiation and relative frequencies of the sexual and asexual cycles among two South African subpopulations were determined to establish whether immigration, mutation and/or recombination contributed towards population structure. The allelic diversity of the initial population (Ngodwana) was observed to be lower (0·16) than that of the more recent Klipkraal population (0·25). Approximately 4% ( G _ST = 0·04) of total gene diversity could be attributed to differences among the subpopulations. Furthermore, six new vegetative compatibility groups (VCGs) have been identified since the initial outbreak of G. circinata in South Africa 10 years ago. The relatively low allelic diversity and low level of genetic differentiation suggest restricted gene flow among subpopulations, and indicate that the pathogen has been introduced recently. However, the amount of allelic and VCG diversity suggests that multiple genotypes have been introduced into South Africa. The increases in effective population number, allelic diversity and new VCGs over the past 10 years suggest that sexual reproduction might be occurring.     

Comparison of populations of the wilt pathogen Ceratocystis albifundus in South Africa and Uganda

Ceratocystis albifundus is an important fungal pathogen of Acacia mearnsii trees in South Africa. In a previous study, a high level of gene diversity was demonstrated in a South African population of C. albifundus . This, together with the occurrence of the pathogen on native Protea species and its exclusive occurrence in South Africa, led to the hypothesis that C. albifundus is probably native to that country. More recently, C. albifundus has been reported from A. mearnsii in south-western Uganda. The aim of this study was to compare the populations of C. albifundus from Uganda and South Africa based on genetic diversity, population structure and possible gene flow. This was achieved using codominant microsatellite markers developed for the closely related species Ceratocystis fimbriata . Available isolates for comparison were from six different areas of South Africa and six jungle stands in Uganda. Eight of the 11 available markers amplified loci in C. albifundus . Gene diversity was higher in the Ugandan population, but genotypic diversity was greater for the South African isolates. There were no common genotypes between the two populations and they shared only 22% of the total alleles. The populations were genetically isolated from each other and highly substructured within. There was no association between isolates collected from the same geographic locations, and gene flow between the two populations was low. Results suggest that C. albifundus was probably not introduced into Uganda from South Africa but rather that an ancestral population, yet to be discovered, is the source of both populations.     

潜在和新发外来入侵物种三维可视化预警监测系统构建与应用

潜在和新发外来入侵物种数据可视化展示是外来入侵物种管理的重要载体。潜在和新发外来入侵物种数据具有混合型(包括结构化和非结构化)和离散性(数据分布在不同的系统或平台)特点。本文在分析这些数据的基础上,以预警监测模型分析与三维可视化集成、多源异构数据融合为切入点,综合运用3D GIS、物联网、大数据等技术手段,研发潜在和新发外来入侵物种可视化系统的关键技术;以潜在外来入侵物种地中海实蝇Ceratitis capitata和新发外来入侵物种番茄潜叶蛾Tuta absoluta为例,构建多源异构数据融合的潜在和新发入侵物种预警监测三维可视化系统,形成了基于GIS技术的典型潜在和新发外来入侵物种可视化平台的解决方案。该系统可为我国潜在和新发外来入侵物种分级控制管理和区域性防控预案制定提供科学支撑。     

我国农业入侵生物科学管控体系形成与发展

生物安全是国家安全的重要组成部分, 生物安全研究技术是当前最活跃的技术领域, 是推动世界新一轮科技革命和产业变革的重要力量之一, 日益成为全球科技竞争的热点领域和各国争相布局的战略制高点。进入21世纪以来, 我国农业外来生物入侵等生物安全问题不断凸显, 直接影响粮食安全、生态安全乃至社会与国家安全。本文总结了近年来我国在生物入侵防控领域研究的现状和所取得的成就, 并结合国际生物入侵研究的发展态势及聚焦我国生物入侵领域技术发展的重大需求, 明确我国农业生物入侵防控研究领域的重大科学问题及科技发展方向和重点任务, 进而定位我国在全球生物入侵科技创新坐标系中的位置, 做好我国在该领域的重大科学工程和战略性科学计划, 为我国中长期生物安全科技发展规划和重大任务部署提供重要决策和依据。     

河南新乡外来植物分布动态调查及其危害性评估

为明确河南新乡外来入侵植物的动态变化及其危害性,近年来跟踪调查了新乡外来入侵植物的种类和分布情况,筛选出近5年来（2006-2010年）在新乡新发现的外来植物,并结合相关研究结果,评估其在新乡的入侵风险。结果表明,2005年,河南新乡有58种外来入侵植物,2006-2010年间,调查发现4种新入侵的外来植物,其中菊科植物3种,茄科植物1种。这4种外来入侵植物中,苏门白酒草的入侵风险最高,黄顶菊正处于扩张期,胜红蓟未发现野外定殖群落,假酸浆危害潜力较小。     

Effects of the invasive shrub,Lantana camara,on soil properties in the Eastern Cape,South Africa

Lantana camara L. is an invasive alien shrub of worldwide significance due to its impacts on biodiversity. It can alter the soil properties of invaded ecosystems and, as a result, affect management outcomes. However, knowledge on the impacts of L. camara on soil properties is scanty, especially in South Africa, despite the pervasive presence of the plant in the country. In this comparative study, the soils underneath L. camara were assessed in order to determine if they had different properties (soil physico‐chemical properties, penetration resistance, infiltration, hydraulic conductivity and water repellency) in comparison to the soils in adjacent natural sites in the Eastern Cape, South Africa. Soil samples were collected from the top soil beneath the canopy of both L. camara‐invaded and adjacent natural sites in five different locations over three summer months. The soils that were collected from underneath L. camara had a significantly higher total C, total P, gravimetric soil moisture (in November and December) and were repellent, compared to the soils in the adjacent natural sites. Soil penetration resistance was significantly higher in the natural sites than in the L. camara‐invaded sites. The soil hydraulic conductivity, soil infiltration rate, soil pH, exchangeable cations and total N showed no significant difference between the invaded and the natural sites. It appears that the soils underneath L. camara have a high total C and total P, soil moisture and are repellent, thus influencing nutrient cycling, potentially making the soil properties underneath it ideal for its own growth. This could contribute to the success of L. camara as an invasive species.     

Genetic study of Mediterranean and South American populations of tomato leafminer Tuta absoluta (Povolny, 1994) (Lepidoptera: Gelechiidae) using ribosomal and mitochondrial markers

BACKGROUND: Before its introduction into Europe at the end of 2006, Tuta absoluta (Povolny, 1994) was confined solely to South America. Currently, this invasive pest is well established in various European and Mediterranean countries, causing important economic losses to tomato (Lycopersicon esculentum Mill.) crops. In order to study the genetic variability of this pest, 23 Mediterranean and ten native South American populations were analysed with nuclear ribosomal DNA (rDNA) and mitochondrial DNA (mtDNA) markers. RESULTS: The internal transcribed spacers 1 (ITS1) and 2 (ITS2) of rDNA and a fragment in the mtDNA gene encoding cytochrome oxidase I (COI) were PCR amplified and sequenced in T. absoluta. Sequence analyses consistently revealed neither intrapopulation nor interpopulation variation in either genomic region. CONCLUSIONS: High genetic homogeneity was detected in T. absoluta populations from the Mediterranean Basin and South America, based on mtCOI and ITS rDNA sequence analysis. A single genetic type was identified in this pest. Copyright © 2011 Society of Chemical Industry     

The large‐scale removal of mammalian invasive alien species in Northern Europe

Numerous examples exist of successful mammalian invasive alien species (IAS) eradications from small islands (<10 km²), but few from more extensive areas. We review 15 large‐scale removals (mean area 2627 km²) from Northern Europe since 1900, including edible dormouse, muskrat, coypu, Himalayan porcupine, Pallas' and grey squirrels and American mink, each primarily based on daily checking of static traps. Objectives included true eradication or complete removal to a buffer zone, as distinct from other programmes that involved local control to limit damage or spread. Twelve eradication/removal programmes (80%) were successful. Cost increased with and was best predicted by area, while the cost per unit area decreased; the number of individual animals removed did not add significantly to the model. Doubling the area controlled reduced cost per unit area by 10%, but there was no evidence that cost effectiveness had increased through time. Compared with small islands, larger‐scale programmes followed similar patterns of effort in relation to area. However, they brought challenges when defining boundaries and consequent uncertainties around costs, the definition of their objectives, confirmation of success and different considerations for managing recolonisation. Novel technologies or increased use of volunteers may reduce costs. Rapid response to new incursions is recommended as best practice rather than large‐scale control to reduce the environmental, financial and welfare costs. © 2016 Crown copyright. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

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.     

北京地区外来入侵生物种类调查初报

通过调查研究和查找有关文献资料明确,北京地区外来入侵生物种类有动物11种,植物23种,列出了其主要的分布范围及其危害,讨论了外来入侵生物的防治对策。对一些危害严重的种类应迅速根除或控制,在引种前或应用前应对有潜在危险的种类进行科学的风险评估,对北京周边地区发生的入侵生物种类应该严格监管和防范。     

Genetic variation of the invasive Campuloclinium macrocephalum,Asteraceae in South Africa,inferred from molecular markers

Campuloclinium macrocephalum is native to Central and South America, but is a highly invasive weed in South Africa, where it is commonly known as the ‘pompom weed’. It is targeted for biological control, the success of which will depend on host specificity and biotype compatibility to its full genetic diversity in South Africa. We investigated the genetic diversity and phylogeography of 52 specimens from across South Africa, 14 from Argentina and three from Brazil using nuclear ribosomal ITS regions. We further explored the AFLP marker diversity in 54 South African, 25 Argentine and three Brazilian specimens. Maximum parsimony analysis of the ITS sequence data produced an unresolved phylogeny. However, three haplotypes were recognised via network analysis. All South African, one Brazilian and all bar one of the Argentine individuals shared a single haplotype. AFLP analyses generated two genetic clusters with a low net nucleotide distance of 0.115 and further revealed that most plants were a mixture of alleles from these two genetic clusters. Although there was a significant genetic variation among the populations, genetic differentiation and mean heterozygosity were low, suggesting that clonal reproduction may be occurring. The current South African populations may therefore be clonal products with different proportions of genetic admixture introduced more than once. The original point of entry appears to be Gauteng, South Africa. Long‐distance dispersal appears to have played a major role in its spread across South Africa. Candidate Argentine biological control agents should therefore be effective on C. macrocephalum in South Africa.