Drivers of invasive tree and shrub natural regeneration in temperate forests

We assessed drivers of ecological success along resource availability gradients for three invasive woody species: Prunus serotina Ehrh., Quercus rubra L. and Robinia pseudoacacia L. We aimed to check how much of invasion success, measured by invader biomass, is explained by propagule pressure and plant community invasibility. Using 3 years of observations from 372 study plots (100 m² each) in temperate forests of Wielkopolski National Park (Poland) we investigated the hierarchy of predictors and partial dependencies using the random forest method. Our study indicated that propagule pressure explained more variance in success of invaders than invasibility—describing availability of resources and competitors in understory vegetation. We also found different responses of seedlings and saplings, connected with dependence on stored carbohydrates, which decreased seedling responses to resource availability gradients. However, resource availability (light and leaf litter predictors) had greater influence than predictors describing understory vegetation. Based on importance and response strength the species studied may be arranged by decreasing requirements for soil fertility and acidity: P. serotina?<?Q. rubra?<?R. pseudoacacia, whereas for light requirements and competition vulnerability the order is: P. serotina?>?Q. rubra?>?R. pseudoacacia. However, low light requirements of R. pseudoacacia may be biased by high proportion of sprouts supplied by parental trees. Results provide guidelines for effective management of invasive woody species in forest ecosystems and describe complex interactions between factors studied on ecological success of invaders.     

Effects of alien invasion by <Emphasis Type="Italic">Bombus terrestris</Emphasis> L. (Apidae) on the visitation patterns of native bumblebees in coastal plants in northern Japan

When alien pollinator species enter a native community of pollinators in which resource partitioning has been established, the pollination network between plants and pollinators may be modified through the interactions between the pollinators over the use of floral resources. We observed the floral-use patterns of native (Bombus hypocrita and B. deuteronymus) and alien (B. terrestris) bumblebee species in a coastal grassland in northern Japan. We analyzed the factors determining resource partitioning patterns. B. hypocrita tended to visit flowers with shallow or wide open corollas, such as Rosa rugosa, whereas B. deuteronymus visited flowers with complex or deeper corollas, such as Lathyrus japonicus. Given the wider floral preference of B. terrestris, floral use by the alien bumblebees consistently overlapped with that of native bumblebees. The visitation of B. terrestris to R. rugosa flowers was positively correlated with that of B. hypocrita. These bumblebee species frequently used similar floral resources, in part because of the large overlap in the seasonality of their foraging activity. The visitation frequency of B. deuteronymus to L. japonicus flowers was independent of the visitation frequency of other bumblebee species. The major visitation periods of the bumblebees to L. japonicus flowers reciprocally differed between B. deuteronymus and B. terrestris, suggesting phenological resource partitioning between these species. Our study suggests that phenological niche partitioning is more common in specialized flowers (L. japonicus) than in generalized flowers (R. rugosa).     

Histological and cytological studies of plant infection by <Emphasis Type="Italic">Erysiphe euonymi</Emphasis>-<Emphasis Type="Italic">japonici</Emphasis>

Powdery mildew caused by Erysiphe euonymi-japonici (Eej) is an increasingly serious fungal disease on Euonymus japonicus that is an important ornamental plant. However, little is currently known about infection and pathogenesis of Eej on E. japonicus. Here, we report plant infection by Eej at the histological and cytological levels. Eej caused severe disease symptoms with white and snow-like colonies on leaf surfaces of E. japonicus. Microscopic observations were conducted continuously to define infection process of Eej on E. japonicus. Eej conidia germinated to produce appressorial germ tubes on leaf surfaces and formed irregular haustoria in plant epidermal cells at 6 h post-inoculation (hpi) and 12 hpi, respectively. After uptaking nutrients from host cells by haustoria, Eej formed numerous hyphae and extensive colonization on leaf surfaces at 96 hpi and finally produced abundant conidiophores and new conidia on leaf surfaces at 168 hpi. In addition, there was consistently a single nucleus in different Eej infection structures and haustorial development could be divided into three major stages, including formation of penetration peg, formation of haustorial neck and initial haustorium, and maturation of haustorium. These results provide useful information for further determination of Eej pathogenesis and finally controlling the disease.     

<Emphasis Type="Italic">Harmonia axyridis</Emphasis> failed to establish in the Azores: the role of species richness,intraguild interactions and resource availability

To understand the role of native ladybird biodiversity in habitat susceptibility on the establishment and spread of Harmonia axyridis Pallas (Coleoptera: Coccinellidae), we characterized and compared European communities where they had established and where they had not established. The local communities of ladybirds were characterized in terms of biodiversity, the average difference in body mass between H. axyridis and other coccinellid species and the rarefied total body mass of all individuals (as a surrogate for aphid abundance and availability). The lack of success of H. axyridis in the Azores, as well as its low success in Southern Europe, can be explained by a combination of resource availability and intraguild competition. We suggest the success of this invasive alien species to establish in a habitat depends first on resource availability and second when most direct competitors for limited resources are absent or are uncommon.     

Modelling the potential geographic distribution of <Emphasis Type="Italic">Trissolcus japonicus</Emphasis>: a biological control agent of the brown marmorated stink bug, <Emphasis Type="Italic">Halyomorpha halys</Emphasis>

Trissolcus japonicus Ashmead (Hymenoptera: Scelionidae) is an endoparasitoid of the eggs of the brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), a major agricultural pest native to China, Japan, South Korea and Taiwan. We used CLIMEX to estimate the potential global distribution of T. japonicus with particular reference to New Zealand. In its native range the model predicts the presence, or a potential expansion, of T. japonicus into most of humid-subtropical and humid-continental areas. Globally, the model projects that many temperate, Mediterranean and subtropical areas could suit the establishment of T. japonicus. In New Zealand, the north appears moderately to highly suitable for T. japonicus, while southern regions are mostly marginal. The risk posed by T. japonicus to non-target species in New Zealand is predicted to vary between different non-targets. CLIMEX projections of the potential distribution of T. japonicus provide guidance for release sites of this parasitoid if approved for importation and release in New Zealand.     

Comparative analysis of otolith morphology in three species of <Emphasis Type="Italic">Scomber</Emphasis>

Geometric morphometrics is a quick and reliable approach to differentiate fish stocks based on the variation of otolith shapes. In this study, morphometric analysis of otolith shapes was used to differentiate three species of Scomber. The sagittae morphology of S. scombrus otolith is totally different from that of S. japonicus and S. australasicus. Multivariate analysis consistently showed that S. japonicus was morphologically similar to S. australasicus, whereas a significant difference in otolith shapes was detected between S. scombrus and other two species of Scomber. The rostrum, antirostrum, excisural notch and dorsal-posterior margin of the otolith reflect the main variations between the three species of Scomber. Shape indices and Fourier coefficients were used to discriminate fish species using analysis of variance and Fisher discriminant analysis. The shape indices successfully differentiated 100%, 95.7% and 96.4% of otoliths in S. japonicus, S. australasicus and S. scombrus, respectively, while the Fourier coefficients only discriminated 70.0%, 61.9% and 91.3% of the sagittae in S. japonicus, S. australasicus and S. scombrus. This study indicates that the shape analysis on the sagittae morphometrics of otoliths is a better method to differentiate species of Scomber.     

A metagenomic assessment of the bacteria associated with <Emphasis Type="Italic">Lucilia sericata</Emphasis> and <Emphasis Type="Italic">Lucilia cuprina</Emphasis> (<Emphasis Type="Italic">Diptera: Calliphoridae</Emphasis>)

Lucilia Robineau-Desvoidy (Diptera: Calliphoridae) is a blow fly genus of forensic, medical, veterinary, and agricultural importance. This genus is also famous because of its beneficial uses in maggot debridement therapy (MDT). Although the genus is of considerable economic importance, our knowledge about microbes associated with these flies and how these bacteria are horizontally and trans-generationally transmitted is limited. In this study, we characterized bacteria associated with different life stages of Lucilia sericata (Meigen) and Lucilia cuprina (Wiedemann) and in the salivary gland of L. sericata by using 16S rDNA 454 pyrosequencing. Bacteria associated with the salivary gland of L. sericata were also characterized using light and transmission electron microscopy (TEM). Results from this study suggest that the majority of bacteria associated with these flies belong to phyla Proteobacteria, Firmicutes, and Bacteroidetes, and most bacteria are maintained intragenerationally, with a considerable degree of turnover from generation to generation. In both species, second-generation eggs exhibited the highest bacterial phylum diversity (20 % genetic distance) than other life stages. The Lucilia sister species shared the majority of their classified genera. Of the shared bacterial genera, Providencia, Ignatzschineria, Lactobacillus, Lactococcus, Vagococcus, Morganella, and Myroides were present at relatively high abundances. Lactobacillus, Proteus, Diaphorobacter, and Morganella were the dominant bacterial genera associated with a survey of the salivary gland of L. sericata. TEM analysis showed a sparse distribution of both Gram-positive and Gram-negative bacteria in the salivary gland of L. sericata. There was more evidence for horizontal transmission of bacteria than there was for trans-generational inheritance. Several pathogenic genera were either amplified or reduced by the larval feeding on decomposing liver as a resource. Overall, this study provides information on bacterial communities associated with different life stages of Lucilia and their horizontal and trans-generational transmission, which may help in the development of better vector-borne disease management and MDT methods.     

Review of the <Emphasis Type="Italic">Ostichthys japonicus</Emphasis> complex (Beryciformes: Holocentridae: Myripristinae) in the northwestern Pacific Ocean,with description of a new species

A taxonomic review of the northwestern Pacific Ocean members of the Ostichthys japonicus complex (Holocentridae: Myripristinae), defined by 3.5 scale rows between the lateral line and spinous dorsal-fin base, recognized three valid species: Ostichthys alamai sp. nov., Ostichthys hypsipterygion Randall, Shimizu and Yamakawa 1982 and Ostichthys japonicus (Cuvier in Cuvier and Valenciennes 1829). Ostichthys alamai, based on 10 specimens (118–179 mm SL) from Panay Island, the Philippines and Sulawesi, Indonesia, is similar to O. hypsipterygion in having longitudinal rows of white spots laterally on the body, but has 17 or 18 (modally 17) pectoral-fin rays [vs. 15 or 16 (15) in the latter], the last dorsal-fin spine fused to the first dorsal-fin soft ray (vs. spine and ray separated), and no white blotch on the pectoral-fin base (vs. white blotch present). It differs from O. japonicus, also occurring in the Philippines, in having relatively longer dorsal- and anal-fin spines, a greater number of well-developed long spinules on the body scales, and rows of white spots laterally on the body (vs. generally absent). Detailed comparisons of O. alamai with other members of the complex are made, and revised diagnoses given for O. hypsipterygion and O. japonicus. Ostichthys sheni Chen, Shao and Mok 1990 and Holotrachys major Whitley 1950 are both regarded as junior synonyms of O. japonicus.     

Polysaccharide degradation systems of the saprophytic bacterium <Emphasis Type="Italic">Cellvibrio japonicus</Emphasis>

Study of recalcitrant polysaccharide degradation by bacterial systems is critical for understanding biological processes such as global carbon cycling, nutritional contributions of the human gut microbiome, and the production of renewable fuels and chemicals. One bacterium that has a robust ability to degrade polysaccharides is the Gram-negative saprophyte Cellvibrio japonicus. A bacterium with a circuitous history, C. japonicus underwent several taxonomy changes from an initially described Pseudomonas sp. Most of the enzymes described in the pre-genomics era have also been renamed. This review aims to consolidate the biochemical, structural, and genetic data published on C. japonicus and its remarkable ability to degrade cellulose, xylan, and pectin substrates. Initially, C. japonicus carbohydrate-active enzymes were studied biochemically and structurally for their novel polysaccharide binding and degradation characteristics, while more recent systems biology approaches have begun to unravel the complex regulation required for lignocellulose degradation in an environmental context. Also included is a discussion for the future of C. japonicus as a model system, with emphasis on current areas unexplored in terms of polysaccharide degradation and emerging directions for C. japonicus in both environmental and biotechnological applications.     

Occurrence of two types of larvae of the Asian seaperch (<Emphasis Type="Italic">Lateolabrax</Emphasis>) in the estuaries of northern Vietnam

Lateolabrax sp. larvae were collected in the Tien Yen and Kalong estuaries of northern Vietnam, the southernmost locality for this genus distribution. Vietnamese Lateolabrax sp. larvae could be distinguished from those of L. japonicus by pigmentation patterns. Their morphological, meristic and pigmentation characters were closer to those of Chinese Lateolabrax than L. japonicus, so Vietnamese Lateolabrax is likely situated as a population of the Chinese one. Morphometric and pigmentation characters of larvae from the two estuaries differed, suggesting that Lateolabrax of northern Vietnam are diversified and consist of at least two different breeding stocks.     

A dynamic energy budget model to describe the reproduction and growth of invasive starfish <Emphasis Type="Italic">Asterias amurensis</Emphasis> in southeast Australia

The introduction of alien species is a global phenomenon that alters ecosystems structure and functioning. Invasive species are responsible for substantial economic and ecological losses. Invasive species impact resource availability, outcompeting and even causing extinction of native species. The management of invasive species requires knowledge on the ecology, physiology and population dynamics of these species. In a world where environmental conditions are changing fast due to global climate change and other anthropogenic stressors, a more comprehensive knowledge of the life history and physiology of these species is urgently needed. The DEB theory is unique in capturing the metabolic processes of an organism through its entire life cycle, and thus, is a useful tool to model lifetime feeding, growth, reproduction, and responses to changes in biotic and abiotic conditions. In this work, we estimated the parameters of a DEB model for Asterias amurensis. This starfish was introduced in Tasmania and is considered the most serious marine pest in Australia where it has caused local extinctions of several species. Asterias amurensis is a major predator and is a keystone species exerting top-down control of its prey populations by achieving large densities. We determined the influence of biotic and abiotic factors on the performance of A. amurensis. The DEB model presented here includes energy handling rules to describe gonad and pyloric caeca cycles. Model parameters were used to explore population dynamics of populations of A. amurensis in Australia. The DEB model allowed us to characterise the ecophysiology of A. amurensis, providing new insights on the role of food availability and temperature on its life cycle and reproduction strategy. Moreover it is a powerful tool for risk management of already established invasive populations and of regions with a high invasion risk.     

Artificial reefs for sea cucumber aquaculture confirmed as settlement substrates of the moon jellyfish <Emphasis Type="Italic">Aurelia coerulea</Emphasis>

In coastal areas with a high intensity of human activities, expansion of artificial structures may enhance Aurelia spp. blooms because these constructions may provide additional substrates for the settlement and proliferation of the polyps. In the present study, the possible occurrence and distribution of Aurelia coerulea ephyrae and polyps were investigated in sea cucumber (Apostichopus japonicus) culture ponds that contain huge amounts of artificial structures. Our results showed that A. coerulea ephyrae were widely distributed in the A. japonicus culture ponds along the Bohai and Yellow Seas. Furthermore, underwater photography revealed that polyps of A. coerulea mainly occurred on the undersides of the artificial reefs made by plastic sunshade nets, tiles and substrate cages. The artificial reefs may decrease the time A. coerulea planulae spend settling, provide more hidden, calm and shady places for the settlement and proliferation of A. coerulea planulae, and thus were suitable substrates for the moon jellyfish A. coerulea. Our study suggests that the A. japonicus culture ponds may act as nursery grounds for the jellyfish A. coerulea and may potentially enhance the blooms of this species in the coastal waters along the Bohai and Yellow Seas.     

Biotic resistance and the spatiotemporal distribution of an invading woodwasp, <Emphasis Type="Italic">Sirex noctilio</Emphasis>

Quantifying the strength of interactions among introduced and native species across space and time is critical in understanding biological invasions as they can attenuate or amplify the magnitude of impact. The European woodwasp, Sirex noctilio F., a global threat to pines, is a recent invader to North America. It attacks and kills primarily Pinus resinosa and Pinus sylvestris, and encounters a diverse assemblage of potential competitors for this resource. We quantified spatial colonization patterns of this woodwasp and resident competitors including scolytine bark beetles, woodboring cerambycid and buprestid beetles, and the fungal root rot diseases Armillaria and Heterobasidion across an 80 year old pine plantation over 4 years. All xylophages were spatially aggregated, but only on a localized scale of 15–20 m. Colonizers occurred non-randomly within trees, with S. noctilio negatively or neutrally associated with all other colonizing agents, whereas all other insect and root rot colonizers were mostly positively co-associated. An autologistic regression with spatially-weighted variables indicated the probability of a dead tree exhibiting symptoms of S. noctilio attack was positively associated with tree density, host species (P. sylvestris), and density of S. noctilio-attacked trees from the current and previous year. Interspecific stand patterns were weaker; probability of attack was negatively associated only with root rot pathogens. Across spatial scales, there were mixed (woodborers) and neutral (bark beetles) associations between S. noctilio and other co-colonizing insects. Our results suggest that competitive interactions with resident species may be contributing to the limited success of S. noctilio in North America, but are unlikely to be driving it by themselves.     

Reproductive tables of predatory phytoseiid mites (<Emphasis Type="Italic">Phytoseiulus persimilis,Galendromus occidentalis</Emphasis>, and <Emphasis Type="Italic">Neoseiulus cucumeris</Emphasis>)

Feeding of predatory mites (Phytoseiulus persimilis, Galendromus occidentalis, and Neoseiulus cucumeris) on different life stages of Tetranychus atlanticus under optimal conditions was studied. Daily and total consumption of prey by predators and selection of prey of different life stages were studied for 5 days and for the entire feeding period. Average daily food consumption [number of individuals] for the entire life period of mature mite females constituted 0.43 females + 5.0 [nymphs and males] + 3.4 eggs of Tetranychus atlanticus in P. persimilis; 0.12 females + 3.70 [nymphs and males] + 3.10 eggs in G. occidentalis; and 0.19 females + 4.10 [nymphs and males] + 3.50 eggs in N. cucumeris. During the entire period of feeding, P. persimilis preferred large individuals and at the postembryonic stages selected prey to a greater extent than G. occidentalis and N. cucumeris (61.8 and 55.1%, respectively). The use of a 5-day express-method is possible for estimation of some biological characteristics of phytoseiids that previously consumed the same food for a long period. In other cases, analysis of characteristics for the entire life period is necessary.     

The lateral line system and its innervation in <Emphasis Type="Italic">Lateolabrax japonicus</Emphasis> (Percoidei <Emphasis Type="Italic">incertae sedis</Emphasis>) and two apogonids (Apogonidae), with special reference to superficial neuromasts (Teleostei: Percomorpha)

The lateral line system and its innervation were examined in a generalized perch-like species, Lateolabrax japonicus (Percoidei incertae sedis), and compared with those in two species of Apogonidae (Fowleria variegata in Apogonichthyini and Ostorhinchus doederleini in Ostorhinchini) characterized by proliferated superficial neuromasts (SNs) on the head, trunk lateral line scales and caudal fin. The total number of SNs differed greatly between the two groups, being 271 in the former, and 2,403 and 4,088 in the latter. The mandibular ramus (MDR) was extensively ramified in the head of the apogonids, with three additional branches that were absent in L. japonicus, innervating 1,117 SNs in F. variegata and 1,928 in O. doederleini. In the apogonids, the additional anterodorsal branch of the MDR coursed parallel to the buccal ramus anteriorly (on the interorbital space) and to the supratemporal ramus posteriorly (on the temporal region). The two parallel portions supplied numerous SN rows forming a characteristic crosshatch pattern, the branch and two rami distributing to transverse and longitudinal rows, respectively. In the two groups, the trunk lateral line scales each housed a canal neuromast (CN; partly replaced by an SN in F. variegata). In addition, one to four (in L. japonicus) and three to 55 (in the apogonids) SNs occurred on each lateral line scale, the pattern of SN innervation being identical in having two types of branches; one innervated a CN and SNs, and the other SN(s) only. The latter type extended only to a limited number of scales in L. japonicus, but to nearly all or all scales in the apogonids. Compared with F. variegata, branches of the respective types were more finely ramified with greater number of SNs in O. doederleini.     

Induction of two cyclotide-like genes <Emphasis Type="Italic">Zmcyc1</Emphasis> and <Emphasis Type="Italic">Zmcyc5</Emphasis> by abiotic and biotic stresses in <Emphasis Type="Italic">Zea mays</Emphasis>

Cyclotides are small plant disulfide-rich and cyclic proteins with a diverse range of biological activities. Cyclotide-like genes show key sequence features of cyclotides and are present in the Poaceae. In this study the cDNA of the nine cyclotide-like genes were cloned and sequenced using 3′RACE from Zea mays. The gene expression of two of these genes (Zmcyc1 and Zmcyc5) were analyzed by real-time PCR in response to biotic (Fusarium graminearum, Ustilago maydis and Rhopalosiphum maydis) and abiotic (mechanical wounding, water deficit and salinity) stresses, as well as in response to salicylic acid and methyl jasmonate elicitors to mimic biotic stresses. All isolated genes showed significant similarity to other cyclotide-like genes and were classified in two separate clusters. Both Zmcyc1 and Zmcyc5 were expressed in all studied tissues with the highest expression in leaves and lowest expression in roots. Wounding, methyl jasmonate and salicylic acid significantly induced the expression of Zmcyc1 and Zmcyc5 genes, but the higher expression was observed for Zmcyc1 as compared with Zmcyc5. Expression levels of these two genes were also induced in inoculated leaves with F. graminearum, U. maydis and also in response to insect infestation. In addition, the 1000-base-pairs (bp) upstream of the promoter of Zmcyc1 and Zmcyc5 genes were identified and analyzed using the PlantCARE database and consequently a large number of similar biotic and abiotic cis-regulatory elements were identified for these two genes.     

Rare triterpene glycoside of ginseng (ginsenoside malonyl-Rg<Subscript>1</Subscript>) detected in plant cell suspension culture of <Emphasis Type="Italic">Panax japonicus</Emphasis> var. <Emphasis Type="Italic">repens</Emphasis>

This paper reports for the first time about the detection and identification of ginsenoside malonyl-Rg₁ (the rare 20(S)-protopanaxatriol-type ginsenoside) in the biomass of plant cell suspension culture of Japanese ginseng (Panax japonicus C.A. Mey. var. repens). Ginsenosides were analyzed by means of high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC-ESI-MS) in positive-ion mode. Malonyl-Rg1 was identified as a result of interpretation of MS spectra obtained upon fragmentation of protonated molecular ion ([M + H]⁺) of this compound in an ionization source. Chromatographic analysis and MS spectra showed that the cells of P. japonicus var. repens cultivated in vitro contain several isomers of malonyl-Rg₁. Thus, we ascertained for the first time that, in addition to malonyl ginsenosides of 20(S)-protopanaxadiol group, the plant cell culture of ginseng P. japonicus var. repens can accumulate glycosides of 20(S)-protopanaxatriol group acylated with a malonic acid residue. The obtained results showed that, in the cells of ginseng cultivated in vitro for a long time (for 10 years and more), the assortment of secondary metabolites (ginsenosides) may be as wide as in intact plants.     

LjCOCH interplays with LjAPP1 to maintain the nodule development in <Emphasis Type="Italic">Lotus japonicus</Emphasis>

Legume plants develop nodules during their symbiotic interaction with rhizobia, and much progress has been made towards understanding Nod factor perception and downstream signaling pathways, while our knowledge about the maintenance of nodule organogenesis was limited. We report here the knockdown mutants of LjCOCH, an ortholog of COCHLEATA in Pisum sativum, cause severe defects in nodule organogenesis in Lotus japonicus. The mature nodule number was drastically decreased accompanied with abnormal lenticel and vascular bundle developmental defects, but not produce roots from nodules in both Ljcoch mutants and LjCOCH-RNAi transgenic hairy roots. LjAPP1, a membrane-associated soluble aminopeptidase P1, was identified to interact with LjCOCH through yeast two-hybrid screening. Unlike that of Ljcoch mutants, insertion mutants of LjAPP1 and LjAPP1-RNAi transgenic hairy roots showed increased nodule number, while the lenticel and vascular development were not affected. Gene expression analysis indicated that LjCOCH and LjAPP1 were differentially upregulated by rhizobia inoculation, and LjNF-YA1 was the major downstream target of LjCOCH and LjAPP1. Our findings suggested that LjCOCH acts as a key factor involved in determinate nodule development through direct interaction with LjAPP1 to regulate the expression of LjNF-YA1, opposite effects of LjCOCH and LjAPP1 provide a dynamic regulation of nodule development in L. japonicus.