Can native grass species outcompete invasive goldenrods? Results of a replacement series experiment

Invasion by alien species is a serious threat to the biodiversity and function of semi‐natural grasslands and may impede restoration efforts in degraded meadows due to high competitiveness. Goldenrods (Solidago and Euthamia species) are considered among the most injurious invaders of grasslands in Central Europe. We tested the hypothesis that native grass species are able to outcompete the invasive goldenrods. A replacement series experiment was established to determine levels of interference between native grass taxa and goldenrods. In the experiment, four alien goldenrod species (Solidago altissima, Solidago canadensis, Solidago gigantea and Euthamia graminifolia) and one native species (Solidago virgaurea) were studied. The native grasses were represented by Lolium perenne (forage and turf varieties) and Festuca pratensis (forage variety). Total biomass was higher in the mixture of species compared with that in monoculture. The higher total biomass was due to higher productivity of the goldenrod species, whereas that of the grasses was reduced. These results demonstrated the high competitiveness of alien goldenrods compared with native grass species.     

Can a specialist parasite species of a widespread and common host species be rare? The case of Spinitectus inermis (Nematoda: Cystidicolidae) in eels Anguilla anguilla

The claim by many authors that Spinitectus inermis (Zeder, 1800), a narrowly specific parasite of European eels Anguilla anguilla (L.), is a rare species is considered at three levels: its geographical range, its frequency of occurrence compared to other eel parasites and its relative abundance in component communities. The parasite is widely distributed in freshwater throughout the European range of the eel but its occurrence is erratic and unpredictable, being known from only 8 countries. Surveys of eel parasites in the United Kingdom and in Continental Europe show that it is present in only 13% of British and 29% of continental localities. This satisfies one of the criteria for rarity. When present, its prevalence ranges from 1.8% to 43.3%, so it can be considered rare in some localities but in a few it may be common and on occasion it may be the dominant species in the gastro-intestinal community. Populations of S. inermis are almost always characterised by high levels of overdispersion, even at low prevalence. The species also displays an ability to colonise a locality following introduction there. Overall it meets many of the criteria of a rare species including a restricted distribution and a low frequency of occurrence and so it can be considered to exhibit diffusive rarity.     

Fractal dimension and shape parameters of asexual Fusarium spores from selected species: Which species can be distinguished?

Journal of Plant Diseases and Protection - Fungi of the genus Fusarium are prominent plant pathogens producing various toxic secondary metabolites. Digital microscopic images were taken from the...     

Can facultative parthenogenesis occur in biparental mealybug species?

The existence of facultative parthenogenesis in mealybugs has been reported by different authors and questioned by others in relation to certain species. We tested the hypothesis of facultative parthenogenesis in relation to three mealybug species, Planococcus citri (Risso), Pseudococcus calceolariae (Maskell) and Pseudococcus viburni (Signoret). The results suggest that these mealybug species are obligate amphimictic.     

Phytogeography of the northeastern coast of the Caspian Sea： native flora and recent colonizations

The northeastern coast of the Caspian Sea is one of the youngest territories for plant colonization in Kazakhstan,and the flora of the most recent portion of this coastal area,the New Caspian marine plain,was chosen to study phytogeographical characteristics of plant species,especially as related to alien origin and invasive potential.Because of the recent formation of this flora,I expected that a large proportion of the species may be alien and invasive.After compiling a comprehensive species list from previous research,I identified the taxonomic,life form,ecological,and geographical structures of the flora.The area belongs to the northern type of deserts with continental climate and low annual precipitation.Taxonomic and life form structures show that the flora is specific to Central Asian deserts.Ecological structure demonstrates a high percentage of halophytes,which resulted from their adaptation to soil salinity and shallow ground waters that occur throughout the study area.Geoelements of the flora indicate allochtonous properties of the flora(i.e.species derived from areas outside the study area) with a low proportion of native(Caspian) plants.Alien species are estimated to comprise 12%-19% of the flora.Although some species have invasive features,severe arid environmental conditions and high salinity of soils and ground waters decrease invasive capacity of exotic plants.However,a threat of expansion of potentially invasive plants exists in the New Caspian marine plain due to the fast growth of anthropogenic habitats associated with recent oil developments.     

Comparing the effectiveness of R genes in a 2-year canola–wheat rotation against Leptosphaeria maculans,the causal agent of blackleg disease in Brassica species

European Journal of Plant Pathology - Blackleg, which is caused by the ascomycete fungus Leptosphaeria maculans, is a major disease of canola in Canada and worldwide. In Canada, canola is usually...     

Salvinia plants in trade: what species are we actually talking about?

Incorrect labelling of plants in trade and misidentification are widespread. Likewise, in trade numerous names are being used for the ornamental aquatic plant known as ‘Kariba weed’, but rarely the correct scientific name Salvinia molesta Mitch. For inspection services of EPPO member countries, correct identification of S. molesta has become important since the species was added to the EPPO A2 List and the List of Union concern in accordance with EU regulation 1143/2014 based on an EPPO Pest Risk Analysis (PRA) for the species. Inspections and a targetted survey of Salvinia plants in trade in the Netherlands were performed and additional material was obtained from wild sources in South Africa, Hungary and the United States. Specimen identification was verified by comparison with the herbarium collection at Naturalis Biodiversity Center in Leiden and with the sequences available in NCBI GenBank database. This paper provides the tools to correctly identity the relevant Salvinia species.     

Invasion syndromes：hypotheses on relationships among invasive species attributes and characteristics of invaded sites

As invasion science accepts that there is no single causal factor for biological invasion,the identification of groups of traits that are often associated,or "syndromes",is a logical move forward.Invasion syndromes are proposed to identify suites of site conditions(biotic and environmental)that render a site vulnerable to invasion by different types of invaders.This paper proposed four invasion syndromes which relate invader attributes(competitive ability,niche construction,phenotypic plasticity,and phenological niche separation)to the biotic characteristics(biodiversity and enemies)and environmental conditions(resource abundance and fluctuation)of invaded sites.The four invasion syndromes described in this paper are a development of hypotheses of how the many factors that influence species invasion might be associated.Invasion Syndrome 1 proposes that sites with relatively high resource abundance and high diversity should be vulnerable to invasion by species with high competitive ability.Invasion Syndrome 2 hypothesizes that sites with relatively low resource abundance and low diversity should be vulnerable to invasion by species with niche construction ability.Invasion Syndrome 3 postulates that sites with moderate or fluctuating resources and moderate diversity should be vulnerable to invasion by species with high phenotypic plasticity.Invasion Syndrome 4 hypothesizes that species introduced into a site where it has phenological niche separation from natives will not have to contend with interference from the biotic community at a site(diversity or natural enemies)and may invade where ever site environmental conditions suit its life history.Further work is needed to support,contradict,or refine these hypotheses and almost certainly will identify more invasion syndromes.     

Microsomal oxidase activity of three blowfly species and its induction by phenobarbital and β-naphtoflavone

Induction of the microsomal oxidase system by dietary phenobarbital and β-naphthoflavone was examined in three blowflies, Phormia regina (Mg.), Lucilia illustris (Mg.), and Eucalliphora lilica (Walk.). Responses were similar in adults and larvae of all species. Phenobarbital increased cytochrome P-450 levels up to 9-fold and aldrin epoxidase up to 138-fold. Increases in cytochrome P-450 and aldrin epoxidase caused by β-naphthoflavone were minor relative to those produced by phenobarbital. In toxicity experiments with carbaryl and propoxur tolerance was associated with the amount of microsomal oxidase activity. Using piperonyl butoxide to synergize carbaryl and propoxur there was no clear indication for the use of either the synergist ratio or synergist difference as an indicator of microsomal oxidase activity.     

Fusarium miscanthi and other Fusarium species as causal agents of Miscanthus × giganteus rhizome rot

In 2010, Miscanthus × giganteus rhizomes were collected from Belgian fields showing emergence reduction and were analyzed for detection and identification of fungal species. All rhizomes were infected by at least one Fusarium species, of which F. culmorum, F. miscanthi, F. crookwellense and F. graminearum were the most abundant. Results of the pathogenicity tests by soil inoculation demonstrate the ability of F. miscanthi, F. culmorum and F. avenaceum to cause rhizome rot disease under greenhouse conditions. This is the first report of F. miscanthi and other Fusarium species isolated from M. × giganteus rhizomes in Belgium.     

Combination effects of herbicides on plants and algae: do species and test systems matter?

Risk assessment of herbicides towards non-target plants in Europe is currently based solely on tests on algae and floating aquatic plants of Lemna sp. Effects on terrestrial non-target species is not systematically addressed. The purpose of the present study was to compare combination effects of herbicide mixtures across aquatic and terrestrial test systems, and to test whether results obtained in the traditional aquatic test systems can be extrapolated to the terrestrial environment. This was done by evaluating ten binary mixtures of nine herbicides representing the seven most commonly used molecular target sites for controlling broadleaved weeds. Data were evaluated statistically in relation to the concentration addition model, and for selected concentrations to the independent action model. The mixtures were tested on the terrestrial species Tripleurospermum inodorum (L.) Schultz-Bip. (Scentless Mayweed) and Stellaria media (L.) Vill. (Common Chickweed), and on the aquatic species Lemna minor L. (Lesser duckweed) and the alga Pseudokirchneriella subcapitata (Korschikov) Hindak. For the two mixtures of herbicides with the same molecular site of action, the joint effect was additive. For the eight mixtures of herbicides with different sites of action, two of the mixtures were consistently antagonistic across species, while for the remaining six mixtures the joint effect depended on the species tested. This dependence was, however, not systematic, in the sense that none of the species or test systems (terrestrial versus aquatic) had a significantly higher probability of showing synergistic or antagonistic joint effects than others. Synergistic interactions were not observed, but approximately 70% of the mixtures of herbicides with different sites of action showed significant antagonism. Hence, the concentration addition model can be used to estimate worst-case effects of mixtures of herbicides on both terrestrial and aquatic species. Comparing the sensitivity of the species to a 10% spray drift event showed that the terrestrial species were more vulnerable to all herbicides compared with the aquatic species, emphasising the importance of including terrestrial non-target plants in herbicide risk assessment.     

Fungal-based bioherbicides for weed control: a myth or a reality?

The use of bioherbicides containing fungal active ingredients or natural fungal molecules is one of the possible solutions to reduce the use of chemical products. This paper focuses on studies of bioherbicides, including both living fungi and natural fungal molecules, published in the last 45 years, and their associated weed targets; current problems in the development of bioherbicides are also discussed. Bibliometric methods based on the Web of Science database were used to analyse relevant articles published between 1973 and 2018. Overall analysis suggested that interest in bioherbicides extends over the preceding thirty years, when many potential microorganisms and natural fungal molecules were proposed. Furthermore, analysis of about 229 articles indicated an encouraging exploitable potential, although there is a real gap between the number of experimental studies and the small number of products currently on the market. A dozen fungal-based bioherbicides are on the market in the United States and Canada, while countries, such as China and South Africa, have one, and none is available in Europe. The active ingredients in these bioherbicides are living fungi, but no fungal molecule-based product is thus far on the market. Reasons for this gap include production hurdles, formulation process, ecological fitness, duration of herbicidal effects, and costly and time-consuming registration procedures. However, it is clear that analysis of fungus–plant interactions provides a promising source of bioherbicides that may be applied to appropriate cropping systems for environment-friendly, sustainable weed control.     

Are herbicides a once in a century method of weed control?

The efficacy of any pesticide is an exhaustible resource that can be depleted over time. For decades, the dominant paradigm – that weed mobility is low relative to insect pests and pathogens, that there is an ample stream of new weed control technologies in the commercial pipeline, and that technology suppliers have sufficient economic incentives and market power to delay resistance – supported a laissez faire approach to herbicide resistance management. Earlier market data bolstered the belief that private incentives and voluntary actions were sufficient to manage resistance. Yet, there has been a steady growth in resistant weeds, while no new commercial herbicide modes of action (MOAs) have been discovered in 30 years. Industry has introduced new herbicide tolerant crops to increase the applicability of older MOAs. Yet, many weed species are already resistant to these compounds. Recent trends suggest a paradigm shift whereby herbicide resistance may impose greater costs to farmers, the environment, and taxpayers than earlier believed. In developed countries, herbicides have been the dominant method of weed control for half a century. Over the next half‐century, will widespread resistance to multiple MOAs render herbicides obsolete for many major cropping systems? We suggest it would be prudent to consider the implications of such a low‐probability, but high‐cost development. © 2017 Society of Chemical Industry     

Assessment of three killing agents’ impact on the capturing of Coleoptera species infesting stored wheat

The introduction of three killing agents (propylene glycol, DDVP and water) inside perforated probe traps was evaluated for their efficiency in trapping Coieoptera adults infesting stored cereals. The experiment was carried out in nine steel bins containing wheat, located in Central Greece, in August 1997. For the most of the 26 beetle species found, no significant differences were observed among treatments. ForSitophilus spp.,Typhaea stercorea, Aloasverns advena, Oryzae-philus surinamensis, Latheticus oryzae, Palorns ratzeburgii, P. subdepressus, andTenebroides mauritanicus, significantly less adults were found in the control traps (with no killing agent). Significant differences among three killing agents were observed only forT. stercorea andT. mauritanicus. Given that the traps supplied with killing agents were found to contain adults even in locations where control traps did not, is concluded that the addition of killing agents has increased the detection sensitivity of traps.     

A Survey (1992–1996) of natural enemies of diaspididae species in Antalya, Turkey

Natural enemies associated with armoured scale insects were surveyed in Antalya province during the years 1992-1996. The surveys yielded 16 species of predators and 11 species of parasitoids associated with 11 species of scale insects. One predator species—Lestodiplosisaonidiellae Harris, one hyperparasite species—Ablerusperspeciosus Girault, and one parasitoid species—Coccophagoidesmoeris (Walker), are recorded for the first time in Turkey. Three coleopterans, namely,Chilocorus bipustulatus (Linnaeus),Cybocephalus fodori- minor Endrödy-Younga andRhyzobius lophanthae (Blaisdell), were found to be the most common predators and to be associated with the diverse species of diaspidids in Antalya and are known so also in other parts of Turkey. Among the parasitoids found,Aphytis chrysomphali (Mercet) andAphytis melinus DeBach are known to be relatively important onAonidiella aurantii (Maskell),Aphytis maculicornis (Masi) onParlatoria oleae (Colvée),Aphytis mytilaspidis (LeBaron) onLepidosaphes ulmi (Linnaeus), andEncarsia berlesei (Howard) onPseudaulacaspis pentagona (Targioni Tozzetti), in Antalya and/or other parts of Turkey.     

Cryptic species and population genetic structure of Plasmopara viticola in São Paulo State,Brazil

Downy mildew (Plasmopara viticola) is one of the most important diseases in grape-growing areas worldwide, including Brazil. To examine pathogen population biology and structure, P. viticola was sampled during the 2015/16 growing season from 516 lesions on nine grape cultivars in 11 locations in subtropical areas of São Paulo State, Brazil. For identification of cryptic species, a subsample of 130 isolates was subjected to cleaved amplified polymorphic sequence (CAPS) analysis, and for 91 of these isolates the ITS1 region was sequenced. These analyses suggest that the population of P. viticola in São Paulo State consists of a single cryptic species, P. viticola clade aestivalis. Seven microsatellite markers were used to determine the genetic structure of all 516 P. viticola isolates, identifying 23 alleles and 55 multilocus genotypes (MLGs). Among these MLGs, 34.5% were clonal and represented 93% of the isolates sampled. Four dominant genotypes were present in at least five different locations, corresponding to 65.7% of the isolates sampled. Genotypic diversity (Ĝ = 0.21–0.89) and clonal fraction (0.58–0.96) varied among locations (populations). Most populations showed significant deviation from Hardy–Weinberg expectations; in addition, excess of heterozygosity was verified for many loci. However, principal coordinate analysis revealed no clusters among locations and no significant isolation by distance was found, suggesting high levels of migration. The results indicate that downy mildew epidemics result from multiple clonal infections caused by a few genotypes of P. viticola, and reproduction of P. viticola in São Paulo State is predominantly asexual.     

<Emphasis Type="Italic">Fusarium</Emphasis> species and DON contamination associated with head blight in winter wheat over a 7-year period (2003–2009) in Belgium

The occurrence of Fusarium species in winter wheat in southern Belgium (Wallonia) and the deoxynivalenol content in 692 samples collected in commercial fields in the region’s main cereal growing area were investigated. The main Fusarium species associated with head blight in wheat were identified at levels that varied from year to year. Interactions between fungal species causing head blight in wheat were detected, most of them positive. The years 2007 and 2008 were very conducive to the disease and there was a strong correlation between mean annual deoxynivalenol content and number of days with a mean relative humidity above 80% over a period starting from 7 days before the mean flowering date and ending 16 days after this date. A two-stage approach, based on type of year (at risk or not) and agricultural practices during risk years has been developed to help cereal storage companies reduce the risk of mixing sound and deoxynivalenol-contaminated lots at harvest and to limit the number of analyses.     

过去近60 a黄河流域降水时空变化特征及未来30 a变化趋势

近60 a来,黄河流域的气候发生了明显的改变,对流域地表水文、生态等过程产生了显著影响。利用1961—2018年黄河流域气象站观测的降水资料,分析了近60 a黄河流域降水时空变化特征,在此基础上,利用CMIP6模式中SSP245情景下未来30 a（2018—2047年）的预估结果,结合基于周期叠加的统计预估方法,对未来30 a黄河流域降水的可能变化趋势进行了预估。结果表明：黄河流域降水存在明显的年内、年际和年代际变化特征,显著振荡周期为2～4 a。在整个流域上,年和季节降水在年际尺度上表现出同位相变化特征,而年际变化异常显著区域不同。黄河流域年降水量的变率受季节降水的调制,夏季的降水多而呈现出强烈的区域性,而冬季降水少且全流域变化差异较小;黄河源区的降水在年内和年际尺度上都具有很好的稳定性;流域内受夏季风活动影响区域内的降水减少,受冬季风影响区域内的降水增加。黄河源区过去60 a的年降水表现出20.96 mm·（10a）^-1的增加趋势;预计未来30 a,年降水将以11.53～17.62 mm·（10a）^-1的速率继续增加;河套地区的年降水在过...