Aggressive Species Research Articles

Corrosion Performance of Ti6Al7Nb Alloy in Simulated Body Fluid for Implant Application Characterized Using Macro- and Microelectrochemical Techniques

In this paper, the applicability of Ti6Al7Nb as a more biocompatible alternative for bone and dental implants than Ti6Al4V and pure titanium in terms of corrosion resistance and electrochemical inertness is investigated. The chemical inertness and corrosion resistance of the Ti6Al7Nb biomaterial were characterized by a multi-scale electrochemical approach during immersion in simulated physiological environments at 37 °C comparing its behavior to that of c.p. Ti, Ti6Al4V, and stainless steel. The establishment of a passive regime for Ti6Al7Nb results from the formation of a thin layer of metal oxide on the surface of the material which prevents the action of aggressive species in the physiological medium from direct reaction with the bulk of the alloy. Conventional electrochemical methods such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) provide quantified information on the surface film resistance and its stability domain that encompasses the potential range experienced in the human body; unfortunately, these methods only provide an average estimate of the exposed surface because they lack spatial resolution. Although local physiological environments of the human body are usually simulated using different artificial physiological solutions, and changes in the electrochemical response of a metallic material are observed in each case, similar corrosion resistances have been obtained for Ti6Al7Nb in Hank’s and Ringer’s solutions after one week of immersion (with a corrosion resistance of the order of MΩ cm2). Additionally, scanning electrochemical microscopy (SECM) provides in situ chemical images of reactive metal and passive dielectric surfaces to assess localized corrosion phenomena. In this way, it was observed that Ti6Al7Nb exhibits a high corrosion resistance consistent with a fairly stable passive regime that prevents the electron transfer reactions necessary to sustain the metal dissolution of the bulk biomaterial. Our results support the proposition of this alloy as an efficient alternative to Ti6Al4V for biomaterial applications.

Metagenomic analysis reveals the virome profiles of Aedes albopictus in Guangzhou, China.

Aedes albopictus is an aggressive invasive mosquito species widely distributed around the world, and it is also a known vector of arboviruses. Virus metagenomics and RNA interference (RNAi) are important in studying the biology and antiviral defense of Ae. albopictus. However, the virome and potential transmission of plant viruses by Ae. albopictus remain understudied. Mosquito samples of Ae. albopictus were collected from Guangzhou, China, and small RNA sequencing was performed. Raw data were filtered, and virus-associated contigs were generated using VirusDetect. The small RNA profiles were analyzed, and maximum-likelihood phylogenetic trees were constructed. The small RNA sequencing of pooled Ae. albopictus revealed the presence of five known viruses, including Wenzhou sobemo-like virus 4, mosquito nodavirus, Aedes flavivirus, Hubei chryso-like virus 1, and Tobacco rattle virus RNA1. Additionally, 21 new viruses that had not been previously reported were identified. The mapping of reads and contig assembly provided insights into the viral diversity and genomic characteristics of these viruses. Field survey confirmed the detection of the identified viruses in Ae. albopictus collected from Guangzhou. The comprehensive analysis of the virus metagenomics of Ae. albopictus in this study sheds light on the diversity and prevalence of viruses in mosquito populations. The presence of known and novel viruses highlights the need for continued surveillance and investigation into their potential impact on public health. The findings also emphasize the importance of understanding the virome and potential transmission of plant viruses by Ae. albopictus. This study provides valuable insights into the virome of Ae. albopictus and its potential role as a vector for both known and novel viruses. Further research is needed to expand the sample size, explore additional viruses, and investigate the implications for public health.

Identification, Diversity, and Distribution of Meloidogyne spp. in Vegetable Fields of South Georgia, U.S.A.

Root-knot nematode (RKN; Meloidogyne spp.) is the most prevalent plant-parasitic nematode in vegetable fields of Georgia, with an incidence of 67.3%. Because aggressive RKN species are reported in the southeastern United States, molecular-based identification of RKN species was conducted on soil samples taken from a nematode surveillance study in 2018 from 292 RKN-infested vegetable fields in southern Georgia. The RKN-infested soil was potted with tomato cultivar Rutgers, and individual nematode females were isolated from galled roots and subjected to species-specific PCR and mitochondrial haplotype-based RKN species identification. The incidence (%), mean, and maximum relative abundance (second-stage juveniles per 100 cm3 of soil) of the five RKN species identified consisted of M. incognita (91.9, 486, 14,144), M. arenaria (36.0, 707, 14,144), M. floridensis (2.2, 909, 5,264), M. javanica (5.5, 352, 1,488), and M. haplanaria (0.7, 8, 14). A large proportion of fields (29%) had mixed populations of M. incognita and M. arenaria, which may reflect the region's long history of cotton and peanut cultivation. For unknown reasons, mixed populations of M. incognita and M. arenaria were associated with higher population densities. M. incognita is the most important RKN species in vegetable fields, followed by M. arenaria; therefore, pure or mixed populations of these species should be addressed in nematode management programs. Although at a lower incidence, the newly detected species, M. floridensis and M. haplanaria, have the potential to become a major threat since they reproduce on vegetables with Mi-resistant genes.

Сохранение агрессивности штаммов грибов из рода Fusarium, поражающих подсолнечник, в культуре на разных субстратах и температурных режимах

Species of a genus Fusarium Link. are the most spread fungi infecting agricultural crops including sunflower. Breeding for the resistance promotes the decrease in spreading and development of diseases but to choose breeding material it is necessary to use the most aggressive strains of pathogen. The purpose of the research was to conduct a comparative analysis of preserving of aggressiveness of strains of two species from the genus Fusarium infecting sunflower in a clear culture on the different vegetal substrates. The object of the research was species F. sporotrichioides Sherb. and F. oxysporum (Schlecht.) Snyd. et Hans. var. orthoceras (Appl. et Wr.) Bilai, isolated from the sunflower roots infected with fusariosis. There is presented a range of variability of these strains aggressiveness at preserving temperature +4 °C and +22–28 °C on sterile sunflower seeds, husks, and fragments of plants du ring five months. When preserving the strains of both species at a temperature of +22–28 °C on seeds the significant decrease of the aggressiveness was stated on the third month and on husks – on the forth one. At lowered temperature of +4 °C the aggressiveness of F. sporotrichioides was decreasing insignificantly on sunflower stems and husks during five months, the important decrease of the aggressiveness of F. oxysporum var. orthoceras was stated on the fourth month. We estimated the more aggressive species F. sporotrichioides preserve the high aggressiveness during longer time (five month) than F. oxysporum var. orthoceras.

Identification and Characterization of Colletotrichum Species Causing Tea-Oil Camellia (Camellia oleifera C.Abel) Anthracnose in Hainan, China

Camellia oleifera C.Abel, commonly known as tea-oil camellia, is a type of significant woody oil crop that is widely cultivated in southern China. During 2017–2021, a fungal foliar disease was detected in routine surveys in Hainan. However, diseases of tea-oil camellia are seldom reported in Hainan. In this study, 51 Colletotrichum spp. isolates were obtained from the symptomatic samples of tea-oil camellia, collected from three production sites located in Hainan. A polyphasic approach was applied to distinguish Colletotrichum species. All 51 isolates were primarily characterized morphologically, and six gene regions, including an internally transcribed space of ribosomal DNA (ITS), chitinsynthase (CHS-1), β-tubulin (TUB), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and manganese-superoxide (SOD2), were sequenced for each isolate. By combining morphological characterization with multilocus sequence analysis (MLSA) based on the six genes, the fungal isolates were identified, representing three Colletrotrichum species: C. fructicola, C. siamense, and C. cordylinicola. The most predominant species was C. fructicola. In pathogenicity tests on the tea-oil camellia cultivar (Reyan1), all collected isolates were pathogenic on tea-oil camellia leaves and were reisolated from symptomatic leaves. Colletotrichum fructicola was the most aggressive species on the attached leaves. This is the first report of C. cordylinicola affecting tea-oil camellia anthracnose worldwide. These results will improve our understanding of the pathogens and provide important insights on the diagnosis and efficient disease management of tea-oil camellia anthracnose.

Seasonal and Periodical Assessment of the Abundance and Diversity of Epigaeic Invertebrates in an Urban Forest Remnant, Dar es Salaam, Tanzania

Urban Forest (UF) refers to a complex human-environment system encompassing urban and peri-urban vegetation such as gardens, rivers and coastal corridors, and uninhabited yards. Human beings benefit from a healthy UF in a variety of ways such as recreation, disasters management, and the lessening of the effects of environmental deterioration (caused by the ongoing anthropogenic activities) like air pollution and ozone concentration affecting many epigaeic fauna. Epigaeic Invertebrates (EIs) are above ground foraging or litter dwelling invertebrates carrying important roles in UFs ecosystems such as ecosystem engineers and pests’ natural enemies. The present study assessed the influence of dry and wet seasons and different periods of a day (morning, afternoon, and evening hours) towards the abundance and diversity of ground dwelling invertebrates around urban forest remnant in Dar es salaam city, Tanzania. Data collection used pitfall trap, baited traps, and dry leaf litter sifting methods. A total of 10,363 EIs individuals were collected with 133 morpho species, 87 families and 18 orders (Hymenoptera dominated by 71.4%). Wet season had significantly higher abundance (6,360 individuals with 121 morpho species) than dry season (4,003 individuals and 88 morpho species), possibly due to the higher availability of food resources during rainy times. However, quite unexpectedly dry season had higher species diversity, probably due to the over dominance of a very aggressive Formicidae species in wet season that displaced some intolerable species. Also, the overall variations of species diversity and abundance between morning, afternoon, and evening hours were significantly different but higher in the morning. This suggested that EIs were active at different times of the day but were more attracted to the morning sunshine and decreased as the land became hotter. This study depicts urban forests to be among world ecosystems with relatively high levels of EIs biodiversity and hence an urgent call for their conservation efforts before it is too late.

Urban Green Spaces and Vector-Borne Disease Risk in Africa: The Case of an Unclean Forested Park in Libreville (Gabon, Central Africa).

In Africa, vector-borne diseases are a major public health issue, especially in cities. Urban greening is increasingly considered to promote inhabitants' well-being. However, the impact of urban green spaces on vector risk remains poorly investigated, particularly urban forests in poor hygienic conditions. Therefore, using larval sampling and human landing catches, this study investigated the mosquito diversity and the vector risk in a forest patch and its inhabited surroundings in Libreville, Gabon, central Africa. Among the 104 water containers explored, 94 (90.4%) were artificial (gutters, used tires, plastic bottles) and 10 (9.6%) were natural (puddles, streams, tree holes). In total, 770 mosquitoes belonging to 14 species were collected from such water containers (73.1% outside the forested area). The mosquito community was dominated by Aedes albopictus (33.5%), Culex quinquefasciatus (30.4%), and Lutzia tigripes (16.5%). Although mosquito diversity was almost double outside compared to inside the forest (Shannon diversity index: 1.3 vs. 0.7, respectively), the species relative abundance (Morisita-Horn index = 0.7) was similar. Ae. albopictus (86.1%) was the most aggressive species, putting people at risk of Aedes-borne viruses. This study highlights the importance of waste pollution in urban forested ecosystems as a potential driver of mosquito-borne diseases.

An update on recent progress of the epidemiology, etiology, diagnosis, and treatment of acute septic arthritis: a review.

Acute septic arthritis is on the rise among all patients. Acute septic arthritis must be extensively assessed, identified, and treated to prevent fatal consequences. Antimicrobial therapy administered intravenously has long been considered the gold standard for treating acute osteoarticular infections. According to clinical research, parenteral antibiotics for a few days, followed by oral antibiotics, are safe and effective for treating infections without complications. This article focuses on bringing physicians up-to-date on the most recent findings and discussions about the epidemiology, etiology, diagnosis, and treatment of acute septic arthritis. In recent years, the emergence of antibiotic-resistant, particularly aggressive bacterial species has highlighted the need for more research to enhance treatment approaches and develop innovative diagnosis methods and drugs that might combat better in all patients. This article aims to furnish radiologists, orthopaedic surgeons, and other medical practitioners with contemporary insights on the subject matter and foster collaborative efforts to improve patient outcomes. This review represents the initial comprehensive update encompassing patients across all age groups.

Competitiveness of Bensulfuron-Methyl-Susceptible and -Resistant Biotypes of Ammannia auriculata Willd. in Direct-Seeded Rice

Ammannia auriculata Willd. (eared redstem) has become one of the most troublesome weeds in paddy rice in China. Resistance to bensulfuron-methyl (BSM) has spread extensively in this species. Greenhouse and field experiments were conducted to determine how the eared redstem biotype and density affect competition against rice. In the greenhouse experiment, five treatments were tested: a BSM-susceptible biotype at low density (58 plants m−2, SL), a BSM-susceptible biotype at high density (288 plants m−2, SH), a BSM-resistant biotype at low density (RL), a BSM-resistant biotype at high density (RH), and a control without eared redstem (CK). Eared redstem grew slowly until 15 days after sowing (DAS); however, growth accelerated after 20 DAS, and the eared redstem plants were taller than the rice from 55 DAS on. The SH and RH treatments were associated with greater intraspecific competition: eared redstem plants in the SH and RH treatments had fewer branches, fewer capsules, and less shoot dry weight per individual plant relative to the SL and RL treatments. The SH and RH treatments also caused greater reductions in the rice yield. The dry weight of rice at 141 DAS was reduced by 73% in the SL treatment, 98% in the SH treatment, 51% in the RL treatment, and 82% in the RH treatment, all relative to the CK. At 141 DAS, BSM-resistant plants were smaller than BSM-susceptible plants, suggesting a fitness cost of herbicide resistance in the absence of a herbicide. In the field study, eared redstem densities as low as 5 plants m−2 reduced the rice yield by 22%. A density of 50 eared redstem plants m−2 reduced the rice yield by 70%. Overall, these findings demonstrate that eared redstem is a highly aggressive weed species and threatens the rice yield even at a low density. However, the findings also demonstrate that BSM-resistant populations are less competitive. There is an urgent need to develop integrated management programs for this aggressive weed, which may include tactics to shift competitive dynamics in favor of rice. Additionally, this research provides the theoretical basis for the damage level, resistance risk evaluation, and management strategy of eared redstem in rice cropping systems.

Geobotanical study of ruderal vegetation in the geoecological monitoring program of roadside ecosystems of the Cherkasy oblast

The article is devoted to the dynamics of the spread of ruderal vegetation in phytocenoses of the roadside ecosystems of the Cherkasy oblast. Due to the high plowed area of the region, roadside field protection strips, in which, in fact, phytocenoses with the participation of ruderal plants are formed, are mostly very narrow (on average 10–15 m). Such ecotopic limitation creates extremely harsh ecological conditions in which only competitive (and sometimes aggressive) species survive. Unlike most works devoted to the formation of the phytodiversity in roadside phytocenoses, the authors follow the concept of infraecosystems presented in previous publications. The main distinguishing feature of this concept is the assumption of different states of formation of natural ecosystems on roadsides. In particular, by comparing the available phytodiversity in roadside phytocenoses with the «National Catalog of Biotopes», the degree of completeness of ecosystem formation at 19 study sites was assessed. Highways in the meridional (11 polygons) and latitudinal (8 polygons) directions were investigated within the Cherkasy oblast. Among the investigated phytocenoses at 19 polygons, only 4 phytocenoses, which spatially coincide with gas stations (Esco gas station, exit from the city of Uman, SOCAR gas station, near the village of Sharyn), or with relatively isolated settlements at the exits to the main route (Bilashki village, Rotmistrivka village). Invasive species (more than 10), which take an active part in the formation of the phytodiversity, were also found at all landfills. According to our estimates, the general trend of the formation of roadside ecosystems falls under the principle of Le Chatelier-Brown compensation, according to which the biosphere confirms its extraordinary ability to support life every time. After all, it can reduce, eliminate, and finally nullify any destructive (man-made) impact, filling existing and creating new ecological niches. Such an understanding of the geobotanical component in monitoring studies will help in the future to more correctly determine the role of man and the biosphere in the formation of anthropogenic landscapes, one of the more dynamic varieties of which are roadside landscapes. Keywords: ruderal plants, infraecosystem, phytocenosis, invasive species.

Identification and distribution of species of Neofusicoccum that cause blueberry stem blight in Chile

ABSTRACT Stem blight is a destructive woody disease of blueberry (Vaccinium corymbosum) caused by several species of the family Botryosphaeriaceae. A field survey was conducted in the mayor blueberry production area of Chile, comprising latitudes 32°49ʹS to 40°55ʹS, to determine the occurrence and distribution of Botryosphaeriaceae in the region. Together, a multilocus analysis, morphological characterization, and phytopathogenicity testing were used to identify 51 Neofusicoccum isolates belonging to N. nonquaesitum (28 strains), N. parvum (22 strains), and N. australe (1 strain). Of these, N. parvum and N. nonquaesitum were the most commonly found, with N. parvum most frequent from latitude 37°40ʹS to the north and N. nonquaesitum predominantly located from the same latitude toward the south. Morphological traits of the isolates were consistent with the species identified by molecular techniques, despite the overlapping of conidial size of some isolates among species. Pathogenicity trials showed that the three species were pathogenic to blueberry plants and revealed that N. parvum and N. nonquaesitum were the most aggressive species, although variability in virulence was observed among isolates of N. parvum and N. nonquaesitum.

Taxonomic identity of Distapliastylifera (Tunicata, Ascidiacea), a new arrival to the eastern Pacific displaying invasive behavior in the Gulf of California, Mexico.

A colonial ascidian of the genus Distaplia caused a mass mortality of the pen shell Atrinamaura (Sowerby, 1835) during June 2016 in the southwest of the Gulf of California (Mexico), with a significant socio-economic cost. Tentatively identified in previous works as Distapliacf.stylifera, a precise taxonomic determination was still lacking. In the present work, based on a detailed morphological study, it is confirmed that this aggressive species is Distapliastylifera (Kowalevsky, 1874). Originally described from the Red Sea, the species currently has a wide circumtropical distribution (with the exception of the Eastern Pacific to date) and is reported as introduced in parts of its range. The present account thus represents an important range extension of this species. However, when revising the original description and later observations, the reported variability of several characters makes it likely that the binomen is in fact a complex of species, as is common in other ascidians with wide distributions. A complete morphological and genetic study including populations from the entire range of distribution would be necessary to settle the status of D.stylifera. Taxonomic uncertainties hinder a correct interpretation of biogeographical patterns and inference on the origin of the studied population. Nevertheless, the known introduction potential of the species, coupled with an explosive growth in an anthropized environment, and the lack of any previous reports in the Eastern Pacific, strongly suggest that the investigated population represents yet another instance of ascidian introduction. From the point of view of management, its invasive behavior is cause for great concern and warrants mitigation measures.

Differential Susceptibility of Coleomegilla maculata and Scymnus creperus Larvae to Aggression by Solenopsis invicta Workers.

The biological control of aphids by aphidophagous coccinellids is often hampered by aphid-tending ants or aggressive, invasive ants foraging for food. Aggressive species such as the imported fire ant Solenopsis invicta Buren may attack and kill coccinellid larvae. This study tested the hypothesis that wax-secreting Scymnus creperus Mulsant larvae are less susceptible than non-wax-secreting Coleomegilla maculata (DeGeer) larvae to S. invicta aggression. Laboratory experiments were set up using bird cherry-oat aphid Rhopalosiphum padi (L.) nymphs and adults (as prey for coccinellids) on barley leaves in arenas with either coccinellid species and with or without S. invicta workers. The presence of S. invicta reduced aphid predation by C. maculata but not Sc. creperus. The frequency of S. invicta attack was greater for C. maculata than Sc. creperus; mortality was significantly greater for C. maculata than Sc. creperus. The wax covering on Sc. creperus reduced S. invicta aggression. Unexpectedly, Sc. creperus larvae with the wax cover removed did not suffer more S. invicta attacks or increased mortality. In conclusion, the wax cover and, perhaps, the volatile or non-volatile compounds in the wax and on the integument of Sc. creperus larvae reduce S. invicta aggression. Further research could identify the wax compounds and determine their functionality as semiochemicals against S. invicta.

A Modeling Framework to Frame a Biological Invasion: Impatiens glandulifera in North America.

Biological invasions are a major component of global environmental change with severe ecological and economic consequences. Since eradicating biological invaders is costly and even futile in many cases, predicting the areas under risk to take preventive measures is crucial. Impatiens glandulifera is a very aggressive and prolific invasive species and has been expanding its invasive range all across the Northern hemisphere, primarily in Europe. Although it is currently spread in the east and west of North America (in Canada and USA), studies on its fate under climate change are quite limited compared to the vast literature in Europe. Hybrid models, which integrate multiple modeling approaches, are promising tools for making projections to identify the areas under invasion risk. We developed a hybrid and spatially explicit framework by utilizing MaxEnt, one of the most preferred species distribution modeling (SDM) methods, and we developed an agent-based model (ABM) with the statistical language R. We projected the I. glandulifera invasion in North America, for the 2020-2050 period, under the RCP 4.5 scenario. Our results showed a predominant northward progression of the invasive range alongside an aggressive expansion in both currently invaded areas and interior regions. Our projections will provide valuable insights for risk assessment before the potentially irreversible outcomes emerge, considering the severity of the current state of the invasion in Europe.

Globisporangium and Pythium Species Associated with Yield Decline of Pyrethrum (Tanacetum cinerariifolium) in Australia

Pyrethrum (Tanacetum cinerariifolium) cultivation in Australia, which accounts for the majority of global production of natural insecticidal pyrethrins, is affected by a persistent yield decline which in part is caused by a complex of pathogens. Globisporangium and Pythium species were isolated from crown and roots of pyrethrum plants showing stunting and brown discoloration of crown tissue, and from soil adjacent to diseased plants from yield-decline-affected sites in Tasmania and Victoria, Australia. Ten known Globisporangium species (Globisporangium attrantheridium, G. erinaceum, G. intermedium, G. irregulare, G. macrosporum, G. recalcitrans, G. rostratifingens, G. sylvaticum, G. terrestris and G. ultimum var. ultimum), two new Globisporangium species (Globisporangium capense sp. nov. and Globisporangium commune sp. nov.) and three Pythium species (Pythium diclinum/lutarium, P. tracheiphilum and P. vanterpoolii) were identified through morphological studies and multigene phylogenetic analyses using ITS and Cox1 sequences. Globisporangium ultimum var. ultimum, G. sylvaticum, G. commune sp. nov. and G. irregulare were most abundant. Globisporangium attrantheridium, G. macrosporum and G. terrestris were reported for the first time in Australia. Seven Globisporangium species were pathogenic on both pyrethrum seeds (in vitro assays) and seedlings (glasshouse bioassays), while two Globisporangium species and three Pythium species only caused significant symptoms on pyrethrum seeds. Globisporangium irregulare and G. ultimum var. ultimum were the most aggressive species, causing pyrethrum seed rot, seedling damping-off and significant plant biomass reduction. This is the first report of Globisporangium and Pythium species causing disease in pyrethrum globally and suggests that oomycete species in the family Pythiaceae may have an important role in the yield decline of pyrethrum in Australia.

Top-down and bottom-up control of phytoplankton communities by zebra mussels Dreissena polymorpha (Pallas, 1771)

Zebra mussels (ZM), Dreissena polymorpha (Pallas, 1771), are one of the most aggressive invasive species. ZM have a strong bidirectional impact on phytoplankton because of their high nutrient excretion rates and high grazing pressure. Furthermore, the interactions between excretion and selective grazing are related to the trophic status of a waterbody and could cause unpredictable changes in phytoplankton. We performed three types of experiments: (i) bottom-up where we measured ZM excretion rates; (ii) top-down where we analyzed the effects of ZM on phytoplankton taxonomic structure via grazing in different trophic conditions; (iii) mesocosm experiment where we estimated the combined top-down and bottom-up effects of ZM on phytoplankton assemblages under different trophic conditions. Our first experiment confirmed high excretion rates of dissolved nutrients (PO43− and NH4+) and dissolved organic carbon (DOC) by ZM. The other experiments revealed selective grazing by ZM, where diatoms were mostly selectively rejected, while green algae were preferred. In the top-down experiment, ZM decreased the total biomass of phytoplankton, while in mesocosm experiments where top-down and bottom-up controls acted simultaneously, we observed increased phytoplankton biomass mainly through increases in filamentous green algae. Our experiments show that ZM can influence phytoplankton through a combination of bottom-up and top-down effects that vary with trophic state.

Spatio-temporal patterns of an invasive species Mimosa bimucronata (DC.) Kuntze under different climate scenarios in China

Invasive alien plants pose a serious threat to native ecosystems and their biodiversity. To control their spread and damage, it is critical to clarify the potential distribution patterns of the invaders at the regional scale and their response to climate change. Mimosa bimucronata (DC.) Kuntze, a shrub extremely tolerant of stressful habitat conditions, is used as firewood and hedgerow in the tropics. Since its introduction to China in the 1950s, it has established a sustainable population and become an aggressive invasive species. Due to serious ecological threats in South China, it has been listed as a Key Management Invasive Alien Species. To understand its invasibility in China, two species distribution models (SDMs), BIOCLIM and DOMAIN, were employed to evaluate the main environmental factors regulating its geographical distribution under the current climate and a future climate change scenario with double CO2 concentration. We found an extensive spread of current suitability habitats in South China, concentrated mainly in the tropical-subtropical provinces of Guangdong, Guangxi, Hainan, and Fujian. The complex interplay of local bioclimatic factors shaped the species distribution. Under the current climate, the predicted range was somewhat larger than the current one. Under the climate change scenario, suitable habitats for Mimosa bimucronata would remain similar to the current one. However, its invasiveness in the current biogeographical range would be more serious. The suitability habitats would expand and shift to the Southeastern coastal and Northern parts of South China under future climate change. We suggest adopting early monitoring and eradication measures in potential invasion areas and practical measures to contain its spread. The results could provide a conceptual basis to formulate prevention and control strategies to improve future containment of its invasion.

Using micro-XRF to characterize chloride ingress through cold joints in 3D printed concrete

Digital fabrication methods with concrete have been rapidly developing, with many problems related to component production and material control being solved in recent years. These processes produce inherently layered cementitious components that are anisotropic, and in many cases, produces a weak interface between layers, which are generally referred to as cold joints. While material strength at these interfaces has been well studied in recent years, durability has received less attention, even though cold joints can function as channels for aggressive agents, such as chlorides. This work presents a method using micro-X-ray fluorescence (μXRF) to image chloride ingress into layer interfaces of 3D printed fine-grained concrete specimens produced with varying layer deposition time intervals, and also compares it to neutron imaging of moisture uptake. The results show that cold joints formed after a 1 day time interval are highly susceptible to chloride ingress, and that curing conditions play a major role in how quickly interfacial transport can take place. The μXRF method is also shown to be useful for study of transport of chlorides in cold joints, due to its spatial resolution and direct analysis of an aggressive species of interest.

Oviposition Activity of Mansonia Species in Areas Along the Madeira River, Brazilian Amazon Rainforest.

Mansonia are aggressive mosquito species that are abundant in aquatic ecosystems where the macrophyte plants occur. These mosquitoes are commonly found across the Amazon/Solimões River basin. However, little is known about the oviposition behavior of these species. In the present study, we registered observations on the oviposition activity of 3 species: Mansonia amazonensis, Ma. humeralis, and Ma. cf. titillans, in 5 species of macrophytes in the vicinities of the Madeira River, Porto Velho, State of Rondônia, Brazil. Overall, 197 egg batches were collected. A greater amount of egg batches was found in Salvinia molesta as compared with other macrophytes sampled. In addition, 2 new oviposition habitats were noted in Ludwigia helmintorrhiza and Limnobium spongia. These findings will be important to understand the reproductive dynamics of these mosquitoes in the Brazilian Amazon basin.

Applicability of the Formation Factor for Different Alternative Binder Types Investigated on Mortars

The high energy demand and associated CO2 emissions to produce ordinary Portland cement (OPC) create the need for alternative types of binders that can be produced in a more environmentally friendly manner. These alternative binders either have a reduced OPC content or can be produced entirely without the use of OPC clinker. To allow their widespread use also in reinforced concrete components, these binders must meet the same durability requirements as types of cement that have already been standardized. This requires a thorough characterization of the materials and, in addition, a verification of the applicability of the evaluation criteria known from the traditional binders. One of the most important factors influencing the transport processes in the material and therefore the durability is the penetration resistance of the pore structure for aggressive species, such as chloride ions. One key parameter for describing the pore structure is the formation factor (FF), which is used for various applications to evaluate durability. It is determined based on the ratio of the electrical resistivity of the concrete and of the pore solution. A high resistivity also influences the corrosion process of depassivated steel reinforcement in concrete or mortar: by inhibiting ion transport, the corrosion rate may be limited. In this study, mortars produced with different alternative binders are characterized in terms of their FF and pore size distribution. In addition, chloride migration coefficients determined by the rapid chloride migration test are related to the FF. The test program includes nine different alternative binders and two reference cements. In addition to a CEM I and CEM III/B, two calcined clays and a modified steel mill slag were investigated as supplementary cementitious materials, as well as a calcium sulfoaluminate () cement and a calcium silicate hydrate (C-S-H) binder. Four materials belong to the group of alkali-activated mortars: Two geopolymers and two alkali-activated slags were investigated here. It is shown that the AC resistances and the conductivities of the pore solutions differ greatly among the mortars investigated. The FF is a suitable parameter for a simplified estimation of the chloride penetration resistance of the investigated alternative binders, provided that realistic values of the pore solution conductivities are determined and used for the calculations.