First records of the non-indigenous signal crayfish (<Emphasis Type="Italic">Pacifastacus leniusculus</Emphasis>) and its threat to noble crayfish (<Emphasis Type="Italic">Astacus astacus</Emphasis>) populations in Estonia

This study gives an overview of status and distribution of signal crayfish (Pacifastacus leniusculus), the first NICS in Estonia and its influence on native noble crayfish (Astacus astacus) populations. The first specimen of signal crayfish was caught during the monitoring of noble crayfish in North Estonia in 2008. The signal crayfish has since been found in three additional sites. Test fishing has indicated that the abundance of signal crayfish has been fluctuating between years and among localities. It has had strong negative impact on abundance of one noble crayfish population. The disconnected distribution of signal crayfish strongly suggests that these populations are the result of human-assisted introductions. Real-time PCR analyses proved that signal crayfish carry the causative agent of the crayfish plague, an oomycete Aphanomyces astaci, thus contributing to its spread. Mortalities in noble crayfish populations had been caused by A. astaci strains from A, B and E genotype group.     

Population structure and dynamics of <Emphasis Type="Italic">Procambarus clarkii</Emphasis> (Girard, 1852) in a Mediterranean brackish wetland (Central Italy)

In 2006 an unusual find of Procambarus clarkii, today considered one of the most dangerous exotic crayfish, was made within the preserved brackish Mediterranean biotope “Palude di Torre Flavia” (Rome, Italy). Here the investigation on the population structure and dynamics of P. clarkii inhabiting this brackish wetland is presented in an attempt to describe the life history pattern in this type of habitat. The present study showed that this species has a lower growth rate and higher longevity than other studied European P. clarkii populations, and that it can damage brackish habitats and human livelihoods. The main results of this study chiefly concern the differences found between several life-history parameters of the studied population and those obtained in previous studies. These results showed the high ecological plasticity of P. clarkii, indicate the need to intervene before the species spreads further in brackish water, for the conservation of Mediterranean coastal habitats.     

Biological control of invasive populations of crayfish: the European eel (<Emphasis Type="Italic">Anguilla anguilla</Emphasis>) as a predator of <Emphasis Type="Italic">Procambarus clarkii</Emphasis>

The red swamp crayfish, Procambarus clarkii, is a paradigmatic invader of freshwater systems. Several attempts have been made to mitigate its multiple impacts but none was successful. Among the different methods proposed, the use of the European eel (Anguilla anguilla) as an indigenous predator is promising but the available information about its predatory ability on crayfish is to date scanty. To fill this gap in knowledge, we ran three experiments in wetlands and irrigation ditches in Italy. The first experiment, in the laboratory, was aimed at quantifying the extent of predation by eels on crayfish, the second, in enclosures, the size classes of crayfish mainly preyed and the possible effect of the eels on P. clarkii behaviour, and the third, in the field, its ability to effectively reduce crayfish populations. Results showed that eels prey on small-sized or soft crayfish, attacking them from the back; an indirect effect was to reduce crayfish trophic activity, which in turn might increases crayfish mortality due to starvation and decreases impact on the community. However, as shown in the field, the use of eels should be appropriately calibrated to the context of application. Taken together, our results show that eels might be used as a complement to the traditional trapping method. However, additional studies are necessary to understand the adequate number of eels to be introduced and to develop appropriate methods for quantifying such effects.     

Comparison of trophic function between the globally invasive crayfishes <Emphasis Type="Italic">Pacifastacus leniusculus</Emphasis> and <Emphasis Type="Italic">Procambarus clarkii</Emphasis>

Impacts of invasive species may manifest most strongly if these organisms are highly distinct functionally from the native species they often replace. Yet, should we expect functional differences between native and invasive species of generalist organisms like freshwater crayfish? Some existing evidence has pointed to native and invasive crayfish species as ecologically equivalent. We contribute to this literature by comparing the trophic niches of the globally invasive crayfishes Pacifastacus leniusculus and Procambarus clarkii, by applying carbon and nitrogen stable isotope analyses to replicated allopatric (alone) and sympatric (together) lake populations in western Washington State, USA, where P. clarkii has been recently introduced and P. leniusculus is presumed native. Our study corrected for potential inherent differences in lake food webs as a consequence of lake abiotic or biotic characteristics using random effects in linear mixed effects models. We found that although overall trophic niche size or area of these species was not significantly different, P. leniusculus was significantly higher in trophic position than P. clarkii when also accounting for the effects of body size, sex, and lakes as random effects. This pattern of increased trophic position of P. leniusculus over P. clarkii was conserved over time in one sympatric lake for which we had data over multiple years. Cumulatively, our findings point to trophic differences between the globally cosmopolitan crayfishes P. leniusculus and P. clarkii, particularly when accounting for the ways that ecosystem context can affect food web structure of communities and the trophic resources available to these consumers.     

Role of the olfactory pathway in agonistic behavior of crayfish, <Emphasis Type="Italic">Procambarus clarkii</Emphasis>

Crayfish establish social dominance hierarchies through agonistic interactions, and these hierarchies are maintained through assessment of social status. Chemical signals influence several aspects of fighting behavior, but the specific chemosensory sensilla involved in detecting these signals in crayfish are unknown. The goal of our study was to examine the importance of aesthetasc sensilla—olfactory sensors on the antennules of decapod crustaceans—in regulating changes in fighting behavior in crayfish, Procambarus clarkii, over the course of repeated pairings. We selectively ablated aesthetascs from pairs of crayfish after the first day of trials and compared the behavior of these ablated animals to that of pairs of intact controls. Results show that unablated crayfish significantly decreased the number and duration of fights over repeated pairings, whereas crayfish lacking aesthetascs continued to engage in similar amounts of fighting across all three trial days. This difference shows that aesthetascs regulate fighting behavior in P. clarkii.     

Geographic expansion of the invasive red crayfish <Emphasis Type="Italic">Procambarus clarkii</Emphasis> (Girard, 1852) (Crustacea: Decapoda) in Mexico

The red crayfish Procambarus clarkii, which is native to southcentral USA and northeastern Mexico, has been successfully introduced into several countries around the world. This study documents the geographic expansion of the exotic red crayfish in Mexico and discusses the consequence of a greater propagation of this species in Mexican inland waters. New state records of this crayfish in the Baja California peninsula and in the states of Durango and Sinaloa indicate its progressive dispersion. The propagation of P. clarkii in Mexico has been caused mainly by human introduction, but it is also facilitated because of the species’ tolerance to an ample range of environmental conditions. Because of the invasive capability of P. clarkii, we suspect that this exotic species is competing for habitat and food with native freshwater shrimp of the genus Macrobrachium in many sites of northern Mexico.     

Genome survey sequencing of red swamp crayfish <Emphasis Type="Italic">Procambarus clarkii</Emphasis>

Red swamp crayfish, Procambarus clarkii, presently is an important aquatic commercial species in China. The crayfish is a hot area of research focus, and its genetic improvement is quite urgent for the crayfish aquaculture in China. However, the knowledge of its genomic landscape is limited. In this study, a survey of P. clarkii genome was investigated based on Illumina’s Solexa sequencing platform. Meanwhile, its genome size was estimated using flow cytometry. Interestingly, the genome size estimated is about 8.50 Gb by flow cytometry and 1.86 Gb with genome survey sequencing. Based on the assembled genome sequences, total of 136,962 genes and 152,268 exons were predicted, and the predicted genes ranged from 150 to 12,807 bp in length. The survey sequences could help accelerate the progress of gene discovery involved in genetic diversity and evolutionary analysis, even though it could not successfully applied for estimation of P. clarkii genome size.     

The harvest of freshwater crayfish, <Emphasis Type="Italic">Astacus leptodactylus</Emphasis> (Eschscholtz, 1823) in Turkey

Astacus leptodactylus is naturally and widely distributed in lakes, ponds and rivers throughout of Turkey. It has also been stocked in many freshwater systems in Turkey to establish new populations and to restore crayfish stocks devastated by the plague (Aphanomyces astaci) and some other reasons (i.e., farming and culinary purposes). Human consumption of A. leptodactylushas always been very low in Turkey; therefore, it was exported mainly to Europe until 1986. A plague was observed in 1985 in Eğirdir, Apolyont, Sapanca and Manyas lakes which included the main harvest areas, and the fishery was lost within 2 years. Consequently, crayfish harvest was banned in all populations to control the plague. Because of the plague, over-fishing and pollution, the harvest of A. leptodactylusin Turkey declined from approximately 5000 (1984) to 200 (1991) tons annually. In 2000s, there has been a gradual increase in the rate of harvest of A. leptodactylusin Turkey, reaching approximately 1600–1900 tons annually, but the plague is still observed in this species at certain localities. The present study reveals that A. leptodactylus in Turkey needs professional support for recovery, because the present harvest of A. leptodactylusis still nearly 20% of the crayfish catch in 1980s.     

Chloroplast DNA phylogeography of <Emphasis Type="Italic">Pedicularis</Emphasis> ser. <Emphasis Type="Italic">Gloriosae</Emphasis> (Orobanchaceae) in Japan

Phylogeographic analyses using chloroplast DNA (cpDNA) variation were performed for Pedicularis ser. Gloriosae (Orobanchaceae). Eighty-one plants of 18 populations of 6 species (P. gloriosa, P. iwatensis, P. nipponica, P. ochiaiana, P. sceptrum-carolinum and P. grandiflora) were analyzed. Fifteen distinct haplotypes were identified based on six cpDNA regions: the intergenic spacer between the trnT and trnL 3′exon, trnL 3′exon-trnF, atpB-rbcL, accD–psaI, the rpl16 intron and the trnK region (including the matK gene). Via phylogenetic analyses of the haplotypes, two continental species, P. sceptrum-carolinum and P. grandiflora, were placed at the most ancestral position in the trees. The former species is widely distributed in the Eurasian continent, and the latter is distributed in Far East Asia. Two robust major cpDNA clades (clades I and II) were revealed in the Japanese archipelago, although the statistical values of monophyly of these clades were weak. Clade I included the haplotypes (A-1, A-2, B-1, B-2 and J) of three species (P. gloriosa, P. iwatensis and P. ochiaiana), and Clade II included seven haplotypes (C-D, E-1, E-2 and F-H) of P. nipponica. These results suggest that this series originated on the Eurasian continent and that subsequently populations at the eastern edge of the continent differentiated into the two Japanese lineages. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Hares in Corsica: high prevalence of <Emphasis Type="Italic">Lepus corsicanus</Emphasis> and hybridization with introduced <Emphasis Type="Italic">L. europaeus</Emphasis> and <Emphasis Type="Italic">L. granatensis</Emphasis>

The Italian hare, Lepus corsicanus, was first described in Corsica more than 100 years ago, but the knowledge on the status of the species in this island remains scarce. Moreover, frequent introductions of thousands of individuals from other hare species, namely Lepus europaeus and Lepus granatensis, into Corsica are known to have occurred and an updated assessment of the prevalence of L. corsicanus in Corsica is therefore of utmost importance. Here, to estimate the relative prevalence of the hare species present in Corsica, we conducted a molecular analysis on 67 samples collected by hunters between 2002 and 2007 in 36 Corsican communes. Sequencing of portions of the nuclear gene transferrin and of the control region of the mitochondrial DNA allowed classifying most of the collected samples as belonging to L. corsicanus (70.1%). Of the sampled Corsican communes, 86.1% contained this species, while only in 11.1%, L. europaeus was present. Three of the analyzed specimens showed an inconsistent molecular assignment between markers suggesting a hybrid origin: L. corsicanus × L. europaeus, L. corsicanus × L. granatensis, and L. europaeus × L. granatensis. The first two cases of hybridization had never been described in nature, even in studies focusing on hares from Italy where L. corsicanus and L. europaeus are often sympatric. These results stress the real risk of corrosion of the native gene pool of L. corsicanus via hybridization with introduced species. We highlight the need of urgently rethinking the management plan of hare populations in Corsica.     

A multivariate morphometric study of the iberian representatives of<Emphasis Type="Italic">Potentialla</Emphasis> sect.<Emphasis Type="Italic">Recta</Emphasis> (<Emphasis Type="Italic">Rosaceae</Emphasis>)

A multivariate analysis has been performed in order to study the polymorphisms of the three species ofPotentilla sect.Recta (Th. Wolf)Juzepchuk represented in the Iberian Peninsula:P. asturica Rothm.,P. hirta L. andP. recta L. The variability of 20 characters (quantitative, binary and qualitative) has been evaluated in 76 collections mostly from the Iberian Peninsula and from other European territories, but also from North America, and North Africa. The analyses performed provide support for the recognition of the three species. The most discriminant among the quantitative characters is the width of the long trichomes on the stem, and then the width of the long trichomes on the leaves and the maximum length of the long trichomes. The interval of number of carpels, presence or absence of short eglandular trichomes and the abundance of long eglandular trichomes (>3 mm) are the most discriminant ones among the qualitative ones. The taxonomical position ofP. asturica, which has been previously subordinated as a subspecies within the other two taxa, is discussed. Our results support a good delimitation of this taxon which, on the basis of the morphological characters studied by us, seems to be morphologically more close toP. hirta than toP. recta, but differs significantly from both. A key to the three species is provided.     

Micropropagation of ornamental <Emphasis Type="Italic">Prunus</Emphasis> spp. and GF305 peach,a <Emphasis Type="Italic">Prunus</Emphasis> viral indicator

A micropropagation approach was developed for nine ornamental Prunus species, P. americana, P. cistena, P. glandulosa, P. serrulata ‘Kwanzan’, P. laurocerasus, P. sargentii, P. tomentosa, P. triloba, P. virginiana ‘Schubert’, commercially important in North America, and GF305 peach, commonly used for Prunus virus indexing. The micropropagation cycle based on proliferation of vegetative tissues includes establishment of tissue culture through introduction of shoot meristems in vitro, shoot proliferation, root induction and plant acclimatization steps and can be completed in 5 months. A meristem sterilization protocol minimized bacterial and fungal contamination. Multiple shoot formation in ornamental Prunus was obtained through the use of 1 mg l⁻¹ 6-benzyladenine. For GF305 peach, alteration in the sugar composition, fructose instead of sucrose, and addition of 1 mg l⁻¹ ferulic acid had a significant impact on the shoot proliferation rate and maintenance of long-term in vitro culture. Rooting and plant acclimatization conditions were improved using a two-step protocol with a 4-day root induction in indole-3-butiric acid (IBA)-containing media with consequent 3-week root elongation in IBA-free media. One-month incubation of rooted shoots in a vermiculite-based medium resulted in additional shoot and root growth and provided better acclimatization and plant recovery. The micropropagation approach can be used for maintenance of the clonal properties for Prunus spp. as well as a protocol to support meristem therapy against viral infection.     

The first record of the non-indigenous signal crayfish <Emphasis Type="Italic">Pasifastacus leniusculus</Emphasis> in Norway

The non-indigenous signal crayfish Pasifastacus leniusculus was registered for the first time in Norway in October 2006. The location represents an isolated pond about 100 km in air line from the nearest known signal crayfish population in the neighbouring country Sweden without any connecting watercourses. The occurrence is therefore undoubtedly caused by human introduction. Molecular analyses confirmed that tested individuals from the signal crayfish population were carriers of the crayfish plague agent Aphanomyces astaci. Disease carrying signal crayfish represents a severe threat to the indigenous and endangered noble crayfish Astacus astacus. Norwegian authorities are currently considering actions for the eradication of the signal crayfish population.     

Colonization of freshwater habitats by an introduced crayfish, <Emphasis Type="Italic">Procambarus clarkii</Emphasis>, in Southwest Iberian Peninsula

The introduction of some crustacean species has produced alterations of freshwater environments and declines of native species worldwide. The red swamp crayfish, Procambarus clarkii Girard, was introduced in the Southwest Iberian Peninsula in the 1970’s, producing severe impacts on rice agriculture and on native biota such as macrophytes, gastropods, native crayfish and amphibians. We studied the distribution of P. clarkii in two areas of SW Iberian Peninsula: the Sado River basin (SW Portugal), an area colonized by this species around 1990, and the Parque Natural del Entorno de Doñana (SW Spain), colonized soon after its introduction in the Iberian Peninsula, in the 1970’s. Our main goal was to determine which factors limit crayfish distribution, which could help to identify the most effective management practices to contain its spread. Procambarus clarkii was found in most types of water bodies, including small and shallow ones. Distance to a crayfish source was the single predictor variable explaining crayfish occurrence in most types of habitats and in both areas. The only exception was for the Sado permanent stream points, where crayfish presence was negatively affected by an interaction between elevation and flow velocity. Other habitat characteristics have apparently little or no importance for its successful colonization. Moreover, this study indicated that overland dispersal is apparently a frequent phenomenon in this species. Our findings can be used to determine which habitats are most likely to be colonized by the crayfish and to develop practical measures which may limit its spread and minimize its impacts.     

Molecular phylogeny of relict-endemic <Emphasis Type="Italic">Liquidambar orientalis</Emphasis> Mill based on sequence diversity of the chloroplast-encoded <Emphasis Type="Italic">mat</Emphasis>K gene

The genetic diversity and evolutionary divergence in Liquidambar species and Liquidambar orientalis varieties were compared with respect to the matK gene. A total of 66 genotypes from 18 different populations were sampled in southwestern Turkey. The matK region, which is about 1,512 bp in length, was sequenced and studied. L. orientalis, L. styraciflua, and L. formosana had similar magnitude of nucleotide diversity, while L. styraciflua and L. acalycina possessed higher evolutionary divergence. The highest evolutionary divergence was found between L. styraciflua and eastern Asian Liquidambar species (0.0102). However, the evolutionary divergence between L. orientalis and other species was of a similar magnitude. The maximum-parsimony phylogenetic tree showed that L. styraciflua and L. orientalis formed a closer clade while East Asian species were in a separate clade. This suggests that the North Atlantic Land Bridge through southern Greenland may have facilitated continuous distribution of Liquidambar species from southeastern Europe to eastern North America in early Tertiary period. The maximum-parsimony tree with only 18 Oriental sweetgum populations indicated that there were two main clusters: one with mainly L. orientalis var. integriloba and the other with var. orientalis and undetermined populations. High nucleotide diversity (0.0028) and divergence (0.00072) were found in L. orientalis var. integriloba populations and Muğla-1 geographical region. This region could be considered as the major refugium and genetic diversity center for the species. The low genetic diversity and divergence at intraspecies level suggest that L. orientalis populations in Turkey share an ancestral polymorphism from which two varieties may have evolved.     

Prevalence of <Emphasis Type="Italic">Wolbachia</Emphasis> Infection in <Emphasis Type="Italic">Bemisia tabaci</Emphasis>

Wolbachia are obligate intracellular bacteria present in reproductive tissues of many arthropod species. It has been reported that few silverleafing populations of Bemisia tabaci were positive for Wolbachia, whereas non-silverleafing populations were more likely infected with Wolbachia and all that infect B. tabaci are Wolbachia belonging to supergroup B. However, current detection methods were shown to be not sensitive enough to uncover all infections. Herein, a protocol based on polymerase chain reaction–restriction fragment length polymorphism analysis of Wolbachia 16S ribosomal DNA is presented. A systematic survey for the prevalence of Wolbachia infection in natural populations of B. tabaci using this method revealed that (1) all populations of B. tabaci tested positive for Wolbachia and the overall infection rate reached 80.5% (293 positives in 364 tests); (2) both single infection and superinfection existed within individual whiteflies tested; and (3) silverleafing populations of B. tabaci most likely harbored A Wolbachia as single infection, whereas non-silverleafing populations tend to carry B Wolbachia as superinfection. It is clear that the Wolbachia infection pattern is closely related to the genetic races of B. tabaci, and the infection frequencies are apparently much higher than those described previously. This study shows that detection methods can significantly influence estimation of Wolbachia infection. It is supposed that Wolbachia may be acting as a biotic agent promoting rapid differentiation and speciation of B. tabaci. This is the most systematic survey of Wolbachia infection within B. tabaci.     

A revision of the genus <Emphasis Type="Italic">Podococcus</Emphasis> (<Emphasis Type="Italic">Arecaceae</Emphasis>)

Summary  A taxonomic revision of the palm genus Podococcus (Arecaceae) is presented. Two species are recognised: P. barteri, a species relatively widespread in a coastal band from Nigeria to the D. R. Congo and P. acaulis, a species previously considered conspecific to P. barteri, almost exclusively confined to Gabon. The taxonomic history, morphology, distribution and conservation status of the genus and each species are discussed     

Antifungal activity of xenocoumacin 1 from <Emphasis Type="Italic">Xenorhabdus nematophilus</Emphasis> var. <Emphasis Type="Italic">pekingensis</Emphasis> against <Emphasis Type="Italic">Phytophthora infestans</Emphasis>

Potato late blight disease, which is caused by the fungus Phytophthora infestans, results in considerable loss of potato crop yield worldwide. Developing new bio-agents to control this disease is desirable. Xenocoumacin 1 (Xcn1) is an antibacterial substance from the entomopathogenic nematode symbiotic bacterium, Xenorhabdus nematophila var. pekingensis. In this study, we evaluated the antifungal activity of Xcn1, along with its potential activity against Phytophthora infestans, in vitro and in vivo. The results showed that Xcn1 exhibits strong antifungal activity against five species of Phytophthora, with EC₅₀ values ranging from 0.25 to 4.17 μg/mL. Xcn1 not only inhibited mycelial growth of P. infestans, reaching 100% inhibition at 1.5 μg/mL of Xcn1, but also suppressed sporangia production. Xcn1 also showed potent in vivo activity against P. infestans, with 92.63% and 80.27% in detached plants and potted plants, respectively, in comparison with the control. Therefore, Xcn1 has antibiotic activities against P. infestans both in vitro and in vivo.     

<Emphasis Type="Italic">Humulus japonicus</Emphasis> Accelerates the Decomposition of <Emphasis Type="Italic">Miscanthus sacchariflorus</Emphasis> and <Emphasis Type="Italic">Phragmites australis</Emphasis> in a Floodplain

Humulus japonicus in communities of Miscanthus sacchariflorus and Phragmites australis can grow large enough to overtop other species in the Amsa-dong floodplain. Because of strong winds and the weight of Humulus, plants of M. sacchariflorus and P. australis fell in mid-August and were subject to decomposition under its dense shading. To assess the effects of H. japonicus on nutrient cycling in these communities, we collected fresh samples of M. sacchariflorus and P. australis in litterbags and decomposed them under H. japonicus for 9 months, beginning in August. Biomass and organic contents from M. sacchariflorus during this incubation period were 49–51% and 44–48%, whereas those of P. australis were 49–61% and 32–52%, respectively. Their annual k values were 1.61–1.74 and 1.46–3.54, respectively. Initial N concentrations in M. sacchariflorus and P. australis were 13 and 20 mg g⁻¹, while C:N ratios were 31 and 21, respectively. These results indicate that H. japonicus is responsible for the collapse of M. sacchariflorus and P. australis in August and also accelerates their nutrient cycling through rapid decomposition, thereby increasing nutrient circulation in floodplains.     

Micropropagation of <Emphasis Type="Italic">Ailanthus altissima</Emphasis> and <Emphasis Type="Italic">in vitro</Emphasis> heavy metal tolerance

Ailanthus altissima, a fast-growing and contamination-resistant species is investigated for its use in areas contaminated by heavy metals. A micropropagation protocol for A. altissima was developed, cultured shoots were tested for in vitro heavy metals tolerance. Proliferation rate and shoot length were affected by 6-benzylaminopurine (BAP) and Murashige and Skoog’s (MS) salt concentrations, best results were obtained in full strength MS medium supplemented with 1.32 or 2.64 μM BAP. Rooting percentage was strongly influenced by indole-3-butyric acid. Cultures of A. altissima exposed to heavy metals demonstrated a tolerance comparable to species already utilized in phytoremediation.