Japonica Populations Research Articles

Molecular basis of multiple resistance to ACCase- and ALS-inhibiting herbicides in Alopecurus japonicus from China

Fenoxaprop-P-ethyl-resistant Alopecurus japonicus has become a recurring problem in winter wheat fields in eastern China. Growers have resorted to using mesosulfuron-methyl, an acetolactate synthase (ALS)-inhibiting herbicide, to control this weed. A single A. japonicus population (AH-15) resistant to fenoxaprop-P-ethyl and mesosulfuron-methyl was found in Anhui Province, China. The results of whole-plant dose–response experiments showed that AH-15 has evolved high-level resistance to fenoxaprop-P-ethyl (95.96-fold) and mesosulfuron-methyl (39.87-fold). It was shown via molecular analysis that resistance to both fenoxaprop-P-ethyl and mesosulfuron-methyl was due to an amino acid substitution of Ile1781 to Leu in acetyl-CoA carboxylase (ACCase) and a substitution of Trp 574 to Leu in ALS, respectively. Whole-plant bioassays indicated that the AH-15 population was resistant to the ACCase herbicides clodinafop-propargyl, clethodim, sethoxydim and pinoxaden as well as the ALS herbicides pyroxsulam, flucarbazone-Na and imazethapyr, but susceptible to the ACCase herbicide haloxyfop-R-methyl. This work reports for the first time that A. japonicus has developed resistance to ACCase- and ALS-inhibiting herbicides due to target site mutations in the ACCase and ALS genes.

The Pacific decadal oscillation and changes in anchovy populations in the Northwest Pacific

The Pacific decadal oscillation (PDO) has been identified as an important driver for fluctuation of fish populations on the eastern Pacific Ocean. However, the relationship between changes in fish population and climate oscillations on a decadal time scale in the Northwest Pacific is still unclear due to the lack of reliable long-term time series data. In the present study, a time series of Engraulis japonicus (Japanese anchovy) populations was reconstructed using the density of sedimentary fish scales in the Yellow Sea basin. E. japonicus populations and the PDO index showed similar patterns on a decadal time scale. Our results confirm that climate is a major driver of ecological changes on a decadal time scale, and indicate that suitable sea water temperature might be the main forcing of anchovy migration. This work also demonstrates the potential of predicting changes in fish population based on climate records.

Structures and Seasonal Changes of Zostera japonica Population in Tategami-ura, Ago Bay, Mie Prefecture

Structures and Seasonal Changes of Zostera japonica Population in Tategami-ura, Ago Bay, Mie Prefecture

Temporal pattern in biometrics and nutrient stoichiometry of the intertidal seagrass Zostera japonica and its adaptation to air exposure in a temperate marine lagoon (China): Implications for restoration and management

In coastal areas of China, the seagrass Zostera japonica has drastically decreased in the past decades. Swan Lake is an exception, where we found extensive areas of Z. japonica beds. The growth of Z. japonica in the lagoon exhibited strong seasonal variation. The maximum shoot density of 9880±2786shootsm−2 occurred in August. The maximum specific growth rate (SGR) of 4.99±1.99%⋅d−1 was recorded in June 2012. SGR might be a good parameter for assessing the growth status of Z. japonica population. N and P contents in the rhizome were significantly lower than those in the leaf and leaf sheath. Lower C/P ratios suggested P enrichment of the seagrass. The occurrence of Z. japonica in Swan Lake was featured by adapting to the intertidal harsh environments. The transplantation method using sectioned rhizomes would be a potential way for restoration of degraded Z. japonica beds. The establishment of the Rongcheng Swan National Nature Reserve in China has contributed to the survival and expansion of Z. japonica in Swan Lake.

Modeling of the putative distribution of the arbovirus vector Ochlerotatus japonicus japonicus (Diptera: Culicidae) in Germany.

Today, international travel and global freight transportation are increasing and have a direct influence on the introduction and establishment of non-native mosquito species as well as on the spread of arthropod (mosquito)-borne diseases inside Europe. One of the mosquito species that has become invasive in many areas is the Asian rock pool or bush mosquito Ochlerotatus japonicus japonicus (synonyms: Aedes japonicus japonicus or Hulecoeteomyia japonica japonica). This species was detected in Germany in 2008 for the first time. Until today, three different Oc. j. japonicus populations have been documented. Laboratory studies have shown that Oc. j. japonicus can act as a vector for a variety of disease agents. Thus, the knowledge on its current distribution is essential for different measurements. In the present study, ecological niche models were used to estimate the potential distribution of Oc. j. japonicus in Germany. The aim was to detect areas within Germany that could potentially function as habitats for this species. According to our model, areas in western, southern, and central Germany offer suitable conditions for the mosquito and may therefore be at risk for an invasion of the species. We strongly suggest that those areas should be monitored more intensively in the future. For this purpose, it would also be essential to search for possible dispersal routes as well as for natural barriers.

Recently discovered Aedes japonicus japonicus (Diptera: Culicidae) populations in The Netherlands and northern Germany resulted from a new introduction event and from a split from an existing population.

BackgroundOriginally native to East Asia, Aedes japonicus japonicus, a potential vector of several arboviruses, has become one of the most invasive mosquito species in the world. After having established in the USA, it is now spreading in Europe, with new populations emerging. In contrast to the USA, the introduction pathways and modes of dispersal in Europe are largely obscure.MethodsTo find out if two recently detected populations of Ae. j. japonicus in The Netherlands and northern Germany go back to new importations or to movements within Europe, the genetic makeup of mosquito specimens from all known European populations was compared. For this purpose, seven microsatellite loci from a representative number of mosquito specimens were genotyped and part of their mitochondrial nad4 gene sequenced.ResultsA novel nad4 haplotype found in the newly discovered Dutch population of Ae. j. japonicus suggests that this population is not closely related to the other European populations but has emanated from a further introduction event. With five nad4 haplotypes, the Dutch population also shows a very high genetic diversity indicating that either the founder population was very large or multiple introductions took place. By contrast, the recently detected North German population could be clearly assigned to one of the two previously determined European Ae. j. japonicus microsatellite genotypes and shows nad4 haplotypes that are known from West Germany.ConclusionAs the European populations of Ae. j. japonicus are geographically separated but genetically mixed, their establishment must be attributed to passive transportation. In addition to intercontinental shipment, it can be assumed that human activities are also responsible for medium- and short-distance overland spread. A better understanding of the processes underlying the introduction and spread of this invasive species will help to increase public awareness of the human-mediated displacement of mosquitoes and to find strategies to avoid it.

Effects of internal conductance and Rubisco on the optimum temperature for leaf photosynthesis in Fallopia japonica growing at different altitudes

AbstractTo investigate mechanisms of adjustment of the optimum temperature for leaf photosynthesis in alpine plants, we compared the temperature responses of photosynthesis, internal conductance (gi), and the amounts of activated Rubisco (ε) in two Fallopia japonica populations growing at elevations of 100 m (K0100), and 2250 m (F2250). There was an obvious difference in photosynthesis at high temperatures between the two populations, although there was no significant difference in the CO2/O2 specificity of Rubisco. Optimum temperatures for photosynthesis were 25 and 30 °C in F2250 and K0100, respectively. The temperature response of ε was similar to that of photosynthesis. The mean values of ε decreased 25 % (F2250) and 24 % (K0100), for temperatures 5 °C above the optimum for photosynthesis. In contrast, gi exponentially increased with increasing temperature in both populations. There was no significant difference in gi between populations for any given temperature. In both populations, there were no changes in CO2 concentrations at the Rubisco active site, when temperatures were above the photosynthetic optimum temperature. This clearly shows that photosynthetic optimum temperatures were not affected by photosynthetic limitation of CO2 diffusing from intercellular air spaces to Rubisco. Furthermore, the atmospheric pressure had a minor effect on the temperature response of photosynthesis. Thus, the decrease in ε in response to elevated temperatures reduced the photosynthetic optimum temperature in highland population of F. japonica, which was adjusted to the habitat.

English

A reciprocal transplant-replant experiment was carried out to investigate the clonal plasticity and local specialization of OAFE population (O type) and BF population (U type) of a clonal rhizome herb Iris japonica in contrasting reciprocal heterogeneous habitats on Jinyun Mountain. U Population had better performance of plant size and clonal propagation (including allocation to clonal propagation, daughter ramet and fine rhizome) in different reciprocal heterogeneous habitats than O population. Both the population origin and reciprocal spatial heterogeneous habitat had effects on clonal ramets and biomass of clonal components of experimental plants. The plasticity of clonal growth had difference in clonal components to balance High light-Low soil resources (water) (HL) or Low light-High soil resources (LH) due to the ecological isolation of the two I. japonica populations. Our findings indicated that two major types of patterns of spatial covariance of resources can have different effects on the growth and local variation of clonal plants.

Evaluation of body weight of sea cucumber Apostichopus japonicus by computer vision

A postichopus japonicus (Holothuroidea, Echinodermata) is an ecological and economic species in East Asia. Conventional biometric monitoring method includes diving for samples and weighing above water, with highly variable in weight measurement due to variation in the quantity of water in the respiratory tree and intestinal content of this species. Recently, video survey method has been applied widely in biometric detection on underwater benthos. However, because of the high flexibility of A. japonicus body, video survey method of monitoring is less used in sea cucumber. In this study, we designed a model to evaluate the wet weight of A. japonicus, using machine vision technology combined with a support vector machine (SVM) that can be used in field surveys on the A. japonicus population. Continuous dorsal images of free-moving A. japonicus individuals in seawater were captured, which also allows for the development of images of the core body edge as well as thorn segmentation. Parameters that include body length, body breadth, perimeter and area, were extracted from the core body edge images and used in SVM regression, to predict the weight of A. japonicus and for comparison with a power model. Results indicate that the use of SVM for predicting the weight of 33 A. japonicus individuals is accurate (R2=0.99) and compatible with the power model (R2 =0.96). The image-based analysis and size-weight regression models in this study may be useful in body weight evaluation of A. japonicus in lab and field study.

Genetic diversity of different populations of lilyturf revealed by RSAP analysis

Restriction site amplification polymorphism (RSAP) markers were employed to access the genetic diversity and relationship of 120 lilyturf germplasms from different geographical origins. Sixteen RSAP primer pairs generated 326 polymorphic bands, of which 318 (97.55%) were polymorphic. The value of polymorphism information content (PIC) ranged from 0.87 to 0.95 with an average of 0.92. These results indicated there was abundant genetic diversity among samples. The results of data analysis on 20 population showed that the value of percentage of polymorphic locus (PPL), Nei's gene diversity (H) and Shannon's information index (I) were 19.94%-85.58%, 0.082 6-0.210 7, 0.120 6-0.328 1 respectively. The most abundant genetic diversity was found in the O. japonicus population from Zhejiang and the least in the Liriope minor population. The genetic distance among 20 population was 0.024 6-0.286 8, of which the minimum genetic distance was 0.024 6 between population I and population 13 while the maximum 0.286 8 between population 5 and population 15. Coefficient of genetic differentiation among natural populations was 0.115 3 (Gst). And the gene differentiation contributed to 43.07% of the total genetic variation among populations and to 56.93% within populations. The total gene flow (Nm) was 0.660 9. UPMGA clustering analysis was basically similar to of the principle coordinate analysis (PCA). The 120 samples were classified into four major groups, which were basically corresponded with the genetic relationships based on morphological traits. The results of UPMGA and PCA were also consistent with geographical origins.

Distribution and genetic structure of Aedes japonicus japonicus populations (Diptera: Culicidae) in Germany.

In recent years, the number of imported cases of arthropod-borne diseases in Europe, such as dengue fever, has increased steadily, as did the emergence and distribution of invasive insect vectors. Consequently, the risk of disease spreading into previously unaffected regions through invasive mosquitoes is also increasing. One example of an invasive mosquito is Aedes japonicus japonicus (A. j. japonicus), which spread from its original habitat in Japan to North America and Europe. This species has been shown to act as a vector for Japanese encephalitis and West Nile viruses. In Europe, A. j. japonicus has been detected in Switzerland, Belgium, Slovenia, and Germany, where it has become a resident species. Here, we describe the recent spread and genetic structure of A. j. japonicus populations in Germany. By monitoring the species in Baden-Württemberg in 2011 and 2012, we observed a considerable enlargement of the infested area from 54 municipalities in 2011 to 124 municipalities in 2012. To elucidate the colonization of Europe by A. j. japonicus, seven microsatellite loci were studied in 106 individuals sampled in Germany and Switzerland in 2012. The same markers were genotyped in 31 North American and 26 Japanese specimens. Population genetic analyses indicated that A. j. japonicus in Baden-Württemberg and North Rhine-Westphalia represented two genetically distinct populations with FST-values of 0.073-0.152, suggesting that they originated from two independent introduction events in the past. These results are of particular interest in light of vectorial variability for the transmission of viruses and other pathogens in Europe.

Unexpected patterns of admixture in German populations of Aedes japonicus japonicus (Diptera: Culicidae) underscore the importance of human intervention.

The mosquito Aedes japonicus japonicus, originally restricted to temperate East Asia, is now widespread in North America and more recently has become established in Europe. To ascertain the putative number of separate introductions to Europe and examine patterns of expansion we analyzed the genetic makeup of Ae. j. japonicus populations from five cemeteries in North Rhine-Westphalia and Rhineland-Palatinate, two western German federal states, as well as of specimens from populations in Belgium, Switzerland, and Austria/Slovenia. To do so, we genotyped individual specimens at seven pre-existing polymorphic microsatellite loci and sequenced part of the nad4 mitochondrial locus. We found evidence of two different genotypic signatures associated with different nad4 mitochondrial haplotypes, indicating at least two genetically differentiated populations of Ae. j. japonicus in Europe (i.e. two distinct genotypes). Belgian, Swiss, and Austrian/Slovenian populations all share the same genotypic signature although they have become differentiated since isolation. Contrary to expectations, the German Ae. j. japonicus are not closely related to those in Belgium which are geographically nearest but are also highly inbred. German populations have a unique genotype but also evidence of mixing between the two genotypes. Also unexpectedly, the populations closest to the center of the German infestation had the highest levels of admixture indicating that separate introductions did not expand and merge but instead their expansion was driven by punctuated human-mediated transport. Critically, the resulting admixed populations have higher genetic diversity and appear invasive as indicated by their increased abundance and recent spread across western Germany.

Aedes japonicus japonicus (Diptera: Culicidae) from Germany have vector competence for Japan encephalitis virus but are refractory to infection with West Nile virus.

The interplay between arthropod-borne (arbo) viruses and their vectors is usually complex and often exert unique relationships. Aedes japonicus japonicus (Hulecoeteomyia japonica or Ochlerotatus japonicus japonicus), an invasive mosquito species with laboratory proven vector competence for a number of emerging viruses has been newly introduced to Germany and is currently expanding its range throughout the country. On the other hand, West Nile virus (WNV), an emerging arbovirus originating from Africa, is already circulating in several European countries and might soon be introduced to Germany. Because newly introduced and rapidly expanding vector species pose a potential risk for public health in Germany, we assessed the vectorial capacity of German Ae. j. japonicus populations for WNV and Japanese encephalitis virus (JEV). The results indicate that German Ae. j. japonicus are susceptible for JEV but are refractory to infection with WNV. Of 67 Ae. j. japonicus females challenged by feeding of WNV-containing blood, none had measurable amounts of WNV-RNA (0% infection rate) on day 14 post-infection. In contrast, all females challenged with JEV were positive for JEV-RNA (100% infection rate) on day 14 post-infection. The reason for WNV resistance remains to be determined but is independent from co-infection with other flaviviruses or the presence of endosymbiotic Wolbachia, since we found no evidence for other flavivirus infections within 1,033 tested A. j. japonicus females from the sampling region, nor detectable Wolbachia infection within 30 randomly selected individuals.

Interactions between the tillage system and crop rotation on the crop yield and weed populations under arid conditions

Field experiments were conducted in Iran in order to determine the interactions between the tillage system and crop rotation on weed seedling populations and crop yields from 2002 to 2005. No tillage, shallow tillage and deep tillage were the main plots and three crop sequences comprising continuous wheat (W‐W), wheat–canola–wheat–canola (C‐W) and wheat–safflower–wheat–safflower (S‐W) were the subplots. Bromus japonicus, Carthumus lanatus, Polygonum aviculare, Lolium temulentum and Avena ludoviciana were found to be the dominant species. The initial weed population in 2002 was estimated at 65 seedlings per m2 and B. japonicus (∼35 seedlings per m2) was the most abundant species, followed by A. ludoviciana and L. temulentum. The dominant weed species mostly did not favor the combination of S‐W and C‐W with any tillage type. For the B. japonicus population, S‐W in combination with moldboard plowing indicated the lowest seedling population. In conclusion, the crop sequence in combination with tillage would help to control troublesome weed species. Safflower and canola were determined to be effective in reducing the grass weeds. The inclusion of these crops in rotation also increased the total revenue of the cropping systems because of the higher sale price of canola and safflower.

The population-genetic structure of Corbicula japonica prime, 1864 (Bivalvia: Cyrenidae) in estuarine water bodies of the Primorsky Region

The population-genetic structure of the bivalve Corbicula japonica from ten estuarine localities in the Primorsky Region was investigated using nine allozyme loci as gene markers. This study revealed spatial genetic heterogeneity between the investigated populations (Gst = 0.05); its degree was dependent on the distance between populations. No linkage disequilibrium was found for any pair of loci. The index of genetic similarity between pairs of populations varied from 0.916 to 0.994. The genetic heterogeneity of the C. japonica populations is probably a result of genetic drift balanced by an irregular gene flow. Such an equilibrium may indicate a relatively recent expansion of C. japonica, which may have occurred during the Holocene climatic optimum (about 7500 years ago).

Cytochrome b gene reveals panmixia among Japanese Threadfin Bream, Nemipterus japonicus (Bloch, 1791) populations along the coasts of Peninsular Malaysia and provides evidence of a cryptic species

We evaluated genetic differentiation among ten presumed Japanese threadfin bream, Nemipterus japonicus populations along the coast of Peninsular Malaysia based on the partial sequence of the mitochondrial cytochrome b gene (982 bp). Genetic divergences (Kimura-2 parameter) ranged from 0.5% to 0.8% among nine of the ten populations while these nine populations were 4.4% to 4.6% diverged from the Kuala Besar population located at the Northeast coast. The constructed Neighbour Joining (NJ) phylogenetic trees based on haplotypes showed the Kuala Besar population forming an isolated cluster. The Analysis of Molecular Variance (AMOVA) of the ten populations a priori assigned into four regions, revealed that most of the variation occurred within population with a fairly low but significant level of regional differentiation (FST = 0.07, p < 0.05, FSC = 0.00, p > 0.05 and FCT = 0.07, p < 0.05) attributed to the Kuala Besar population. p Value after Bonferroni correction revealed that only pairwise FST values involving the Kuala Besar population with the other nine populations were significant. Thus, this study revealed that the N. japonicus populations off Peninsular Malaysia were panmictic. However, the Kuala Besar population, although morphologically identical was composed of a genetically discrete taxon from the rest. These findings are important contributions in formulating sustainable fishery management policies for this important fishery in Peninsular Malaysia.

Recruitment of the subtropical coral Alveopora japonica in the temperate waters of Jeju Island, South Korea

The zooxanthellate scleractinian coral, Alveopora japonica Eguchi, 1968, inhabits high-latitude waters from southern Taiwan to mainland Japan. This species may have benefited from recent increase in seawater temperature, and it has been hypothesized that a shift from kelp forest to coral dominance may be occurring at some locations at the edge of its distribution. Here, we examined the coral diversity and composition of the benthic community associated with extensive A. japonica stands from Biyangdo, northeast of Jeju Island (33.41°N), South Korea. Coral recruit density was further examined by estimating the number of juvenile corals in photographs taken directly from the benthos. The depauperate coral assemblage (five species in total) was dominated by A. japonica, which contributed to 64.0% ( SE 1.4%) of the benthic cover. Together with local reports documenting recent development of A. japonica populations, the exceptionally high density of recruits, 7590 (SE 660) recruits per m 2 , suggests a population that could be increasing. Additional data are needed to correlate the trend observed in this population with rising seawater temperature. However, this weedy and opportunistic coral species may be colonizing the region more aggressively than expected by chance, possibly to the detriment of the original ecosystem dominated by macroalgae. Overall, this work constitutes an important baseline against which future changes recorded in the temperate benthic communities can be assessed.

Genetic Variability and Reproduction Structure of &amp;lt;i&amp;gt;Corbicula japonica&amp;lt;/i&amp;gt; in Major Fishing Brackish Lakes in Japan

Corbicula japonica is the best-known bivalve inhabiting widely in brackish estuaries and lakes in Japan. Although this species has been most commercially important species of inland fisheries in Japan, the gradual decline in its production over 40 years caused not only economic problems in fishery industry but also ecological disturbances in biodiversity conservation. The aim of this study was to evaluate the reproduction structure of C. japonica populations in major fishing brackish lakes based on the genetic diversity inferred by mitochondrial DNA sequence analysis of the cytochrome oxidase c subunit I gene. Of a total of 188 C. japonica individuals collected in Lakes Shinji, Jusan, Ogawara and Abashiri, 25 haplotypes were obtained, and only the haplotype HT01 was apparent with relatively high abundance in all lakes. Minimum spanning network analysis of haplotypes showed different population structures between Lake Shinji and Lakes Jusan, Ogawara and Abashiri. In addition, pairwise population genetic distance FST and ΦST values were significantly higher in Lake Shinji than Lakes Jusan, Ogawara and Abashiri. The mismatch distribution analysis showed unimodal profile for Lakes Jusan and Ogawara and bimodal profile for Lakes Shinji and Abashiri. Those results indicate a recent population expansion in all lakes, and Lakes Shinji and Abashiri and Lakes Jusan and Ogawara maintained continuous reproduction structure and suffered to rapid population growth, respectively.

Implementation of surveillance of invasive mosquitoes in Belgium according to the ECDC guidelines.

BackgroundIn 2012, the new guidelines for the surveillance of IMS in Europe, produced by the European Centre for Disease Prevention and Control (ECDC), were tested in Belgium. This study aimed at (1) testing the usefulness and applicability in the field of the ECDC guidelines for the surveillance of IMS in Europe and (2) surveying IMS throughout Belgium.MethodsFirst, the scenarios, which Belgium is facing, were identified according to the ECDC guidelines. Second, the surveillance strategy and the methods were identified based on the guidelines and adjusted to the Belgium context. Two areas colonised by IMS and 20 potential points of entry (PoE) were selected. Mosquito Magnet Liberty Plus (CO2-baited) traps (23) and oviposition traps (147) were set-up, and larval sampling was performed monthly or bi-monthly from July till October 2012. Finally, the costs and workload of the surveillance activities were compared to the estimates provided by the ECDC guidelines.ResultsSurveillance at 20 potential PoE (complying with scenario 1) revealed that no new IMS were established in Belgium. Surveillance at two sites colonised by IMS (scenario 2) indicated that although control measures have drastically reduced the Ae. j. japonicus population this species is still present. Furthermore, Ae. koreicus is permanently established. For both scenarios, the problems encountered are discussed and recommendations are given. In addition, the actual workload was lower than the estimated workload, while the actual costs were higher than the estimated ones.ConclusionsThe ECDC guidelines are helpful, applicable and efficient to implement surveillance of IMS in Belgium. Recommendations were customised to the local context (political demands, salary and investment costs, and existing expertise). The workload and costs related to the preparatory phase (i.e., planning, contacts with the PoE, writing a protocol) were found to be missing in the cost evaluation suggested in the guidelines. Updates on the occurrence of IMS in Belgium and the related risk for disease agents they can transmit will only be available once a structured and permanent surveillance system is implemented.

Development and characterization of microsatellite markers in the coffee-family herb Ophiorrhiza japonica (Rubiaceae)

Ophiorrhiza japonica (Rubiaceae) in Taiwan shows altitudinal morphological differentiation, suggesting altitudinal genetic differentiation. However, global warming and/or road building are possibly causing human-mediated altitudinal gene flow and genetic disturbance. To investigate this possibility, we developed the first nuclear microsatellite markers for the genus. Using the low-cost compound microsatellite marker technique, 17 markers were developed and nine markers were polymorphic. The number of alleles per polymorphic locus ranged from 2 to 13. At population level, observed (Ho) and expected (He) heterozygosities ranged 0.070–0.831 and 0.068–0.812, respectively. The polymorphic information content ranged 0.066–0.787. No null allele, significant deviation from Hardy–Weinberg equilibrium, or significant linkage disequilibrium was observed. The 17 marker loci were successfully PCR-amplified in three congeneric species except for three cases. The developed microsatellite markers will be used to investigate genetic structure and gene flow among O. japonica populations at different altitudes.