The bad and the super-bad: prioritising the threat of six invasive alien to three imperilled native crayfishes

Multiple species invasions and limited resources for management require prioritisation of deleterious effects of invaders on imperilled native species. This study prioritises the threat of six non-indigenous crayfish species (NICS) to three indigenous crayfish species (ICS) in southwestern Germany, a European region with high diversity of crayfish species and freshwater habitats. Using multivariate statistical analyses and niche-based species distribution models, the (1) contemporary and potential range overlap, (2) habitat overlap, and (3) rate of spread of the nine species were assessed. Predicted and contemporary range overlap with ICS was consistently the highest for the alien signal crayfish. Environmental niches of ICS tended to be associated with cooler temperatures (except for white-clawed crayfish), lower Human Influence Index, and higher terrain slope than that of alien Orconectes and Procambarus species, but were mostly similar to that of signal crayfish. Habitat overlap was found to be the highest between signal crayfish and ICS. In contrast to Orconectes and Procambarus species, signal crayfish also invade headwaters, where the most ICS populations occur. Range expansion during the past 15 years was the highest for signal crayfish, followed by Orconectes species. Because of the great potential to invade as-yet isolated refuge areas and spread at a high rate, signal crayfish is of the highest concern for conservation of ICS and should be primarily targeted by prevention and control measures. However, it merely represents the ‘worst of the worst’, since all NICS of North American origin are natural reservoirs of crayfish plague, a fatal disease of ICS.     

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.     

Predatory impacts of alien decapod Crustacea are predicted by functional responses and explained by differences in metabolic rate

Alien predators can have large impacts on prey. It is important that we understand, and ideally predict, these impacts. Here, we compare predatory impacts of size-matched decapod crustaceans—invasive alien Eriocheir sinensis and Pacifastacus leniusculus, and native European Austropotamobius pallipes—and use this case study to inform methods for impact prediction. We quantify functional responses (FRs) on three macroinvertebrate prey species, examine switching behaviour, and measure metabolic rates as a possible mechanistic explanation for differences in predation. FRs show a consistent pattern: attack coefficients and maximum feeding rates are ordered E. sinensis?≥?P. leniusculus?≥?A. pallipes for all prey species. Attack coefficients of E. sinensis are up to 6.7 times greater than those of size-matched crayfish and maximum feeding rates up to 3.0 times greater. FR parameters also differ between the invasive and native crayfish, but only up to 2.6 times. We find no evidence of switching behaviour in crayfish but suggestions of negative switching in E. sinensis. Differences in FR parameters are mirrored by differences in routine, but not standard, metabolic rate. Overall, our data predict strong predatory impacts of E. sinensis, even relative to alien P. leniusculus. Strong impacts of P. leniusculus relative to A. pallipes may be driven more by body size or abundance than per capita effect. FRs vary between prey types in line with existing knowledge of impacts, supporting the use of FRs in quantitative, prey-specific impact predictions. MRs could offer a general mechanistic explanation for differences in predatory behaviour and impacts.     

Species-specific pattern of crayfish distribution within a river network relates to habitat degradation: implications for conservation

The degradation of aquatic habitats has increasingly become one of the most important factors influencing the distribution of freshwater species worldwide. We analysed the occurrence of three crayfish species, Astacus astacus, Austropotamobius torrentium and Orconectes limosus, in relation to habitat degradation status (based on Directive 2000/60/ES), stream morphology, geographical characteristics and land cover. In total, we analysed 6,768 sites within the Czech Republic (Central Europe), of which 6,187 sites lacked crayfish; among the remainder, A. astacus was present in 507 sites, O. limosus occurred in 44 sites and A. torrentium was present in only 30 sites. The analysis revealed that A. astacus preferred streams of better water quality that were not surrounded by agricultural land or settlements. This species also preferentially occurred in smaller streams with stony bottom substrata that were located at higher altitudes. Austropotamobius torrentium occurrence was associated with the natural character of the water body and the presence of protected areas at higher altitudes. Conversely, the non-native crayfish species O. limosus was typically recorded at lower altitudes in downstream reaches surrounded by agricultural land and with deteriorated water quality. The degree of environmental (human) pressure besides differences in habitat characteristics at sites with ICS and NICS may be of general importance for conservation strategies aimed at central European native crayfish species, primarily because the habitat-driven co-occurrence pattern (and its possible changes in the future) may strongly influence interspecific relationships, such as direct competition and the spread of infectious diseases between crayfish species.     

Ecosystem of Caspian Sea threatened by pet-traded non-indigenous crayfish

Freshwater ecosystems are particularly vulnerable to biological invasions; the aquatic animal pet trade has been recognized as a significant pathway of introductions. Crayfish are considered a model group of traded organisms with a series of highly successful species already established in the wild, having the potential to negatively influence both indigenous crayfish species (ICS) as well as alter occupied ecosystems. Eastern Europe includes the entire native ranges of indigenous Astacus leptodactylus sensu lato and A. pachypus. This region has been largely overlooked and considered relatively safe from the adverse impacts of non-indigenous crayfish species (NICS). In this study, we evaluated the crayfish pet trade in the Lower Volga Region with special emphasis on Astrakhan, the biggest city of Russian Federation in the region located just in the delta of Volga River, thus being a potential gateway of introductions to the Caspian Sea and adjacent freshwaters. The local pet trade involves 12 NICS. Considering their origin, availability, probability of establishment, invasiveness and further aspects, Procambarus fallax f. virginalis, P. clarkii and Cherax destructor are considered potentially the most problematic, including transmission of diseases like crayfish plague caused by Aphanomyces astaci or white spot syndrome virus. Taking this information as a whole, the availability of NICS with a high probability of overlapping the entire range of European ICS means that attention is warranted. Further research is needed to corroborate the abilities of NICS and their associated diseases to withstand specific conditions of the Caspian Sea as well as the adjacent Black and Azov Seas, all possessing different degrees of elevated salinity.     

Transformation of detritus by a European native and two invasive alien freshwater decapods

Invasive alien species have the potential to alter biodiversity and ecosystem processes. In freshwaters, detritus decomposition is a major ecosystem service but it remains uncertain whether invasive alien decapods process detritus differently to natives. This study examined leaf litter processing, and cascading effects on biofilms, by the European native white clawed crayfish (Austropotamobius pallipes) compared to two invasive alien decapod species: the American signal crayfish (Pacifastacus leniusculus) and the Chinese mitten crab (Eriocheir sinensis). Invasive alien decapods were responsible for higher leaf litter decomposition than the native. In comparison with native crayfish, invasive alien crab and crayfish showed higher rates of litter consumption, increased production of smaller leaf fragments, fine particulate organic matter (FPOM) and dissolved organic carbon. Nutrients (ammonia and soluble reactive phosphorous) derived from excretion (measured separately in the absence of biofilms) varied among decapod species, being lower for P. leniusculus. However, nutrient concentrations did not vary among species in the detritivory experiments with biofilm, implying nutrients were utilised for biofilm production and respiration as no differences in biomass were evident among decapod treatments. These results show invasive alien decapods have the potential to increase the magnitude of detrital processing to FPOM in rivers, but indirect impacts on primary producers due to nutrient release are uncertain based on this experimental context.     

Non-indigenous signal crayfish <Emphasis Type="Italic">Pacifastacus leniusculus</Emphasis> are now common in Danish streams: preliminary status for national distribution and protective actions

North American signal crayfish (Pacifastacus leniusculus) are invasive in Europe and pose a serious threat to indigenous European crayfish such as the noble crayfish (Astacus astacus). This is mainly because signal crayfish is the carrier of crayfish plague agent, Aphanomyces astaci, which freshwater crayfish from all other continents are highly susceptible to. Until recently, the distribution of signal crayfish in Danish streams has been considered local and restricted to a small geographical area. Here we present data demonstrating that signal crayfish are now widespread in Denmark, including the largest Danish river, River Gudenå. For one of the rivers where co-existing signal crayfish and indigenous noble crayfish were documented, sensitive molecular tests could not detect the crayfish plague agent Aphanomyces astaci in either species. Hence, it seems that not all signal crayfish are chronic carriers of the disease. For the remaining freshwater systems with the introduced signal crayfish, the infection status is presently unknown. Large areas of the freshwater systems in Denmark also remain unexplored with respect to presence/absence of signal crayfish and noble crayfish. Nevertheless, our preliminary data that covers about 14% of the Danish rivers, strongly suggests that signal crayfish should be considered as a common invader that poses an increased threat to the biota in Danish streams, in particular for the indigenous noble crayfish.     

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.     

Geostatistical distribution modelling of two invasive crayfish across dendritic stream networks

Species distribution models combining environmental and spatial components are increasingly used to understand and forecast species invasions. However, modelling distributions of invasive species inhabiting stream networks requires due consideration of their dendritic spatial structure, which may strongly constrain dispersal and colonization pathways. Here we evaluate the application of novel geostatistical tools to species distribution modelling in dendritic networks, using as case study two invasive crayfish (Procambarus clarkii and Pacifastacus leniusculus) in a Mediterranean watershed. Specifically, we used logistic mixed models to relate the probability of occurrence of each crayfish to environmental variables, while specifying three spatial autocorrelation components in random errors. These components described spatial dependencies between sites as a function of (1) straight-line distances (Euclidean model) between sites, (2) hydrologic (along the waterlines) distances between flow-connected sites (tail-up model), and (3) hydrologic distances irrespective of flow connection (tail-down model). We found a positive effect of stream order on P. clarkii, indicating an association with the lower and mid reaches of larger streams, while P. leniusculus was affected by an interaction between stream order and elevation, indicating an association with larger streams at higher altitude. For both species, models including environmental and spatial components far outperformed the pure environmental models, with the tail-up and the Euclidean components being the most important for P. clarkii and P. leniusculus, respectively. Overall, our study highlighted the value of geostatistical tools to model the distribution of riverine and aquatic invasive species, and stress the need to specify spatial dependencies representing the dendritic network structure of stream ecosystems.     

Distribution and ecological relations among the alien crab, <Emphasis Type="Italic">Percnon gibbesi</Emphasis> (H. Milne-Edwards 1853) and autochthonous species,in and out of an SW Mediterranean MPA

The distribution of the allochthonous crab Percnon gibbesi and its relationships with other benthic invertebrate species was assessed inside the marine reserve of Cabo de Palos—Islas Hormigas (Mediterranean sea, Spain) and neighbouring non-protected sites. Although a significant spatial variability was detected at finer spatial scale, there was no influence of protection measures or insularity on the abundance of P. gibbesi. The presence of small holes, encrusting algae and low slope favour the colonization success of this crustacean, and the spatial distribution of these habitat features could explain the observed pattern. The abundance of P. gibbesi was similar to that of native crab species; however, a non-significant negative relationship between the abundance of P. gibbesi and native crabs (Pachygrapsus marmoratus and Eriphia verrucosa), urchins (Arbacia lixula and Paracentrotus lividus) and a snail (Phorcus turbinatus) was observed. This work highlights the importance of monitoring alien crab population densities taking structural habitat and other potentially influential factors into account and the likely effect of this alien species on the native ones.     

Diatoms prefer strangers: non-indigenous crayfish host completely different epizoic algal diatom communities from sympatric native species

Despite their wide distribution and ecological importance, almost no information is available about the role of freshwater crayfish as basibiont for epizoic algae. Moreover, studies on epizoic freshwater diatoms have been largely neglected. In this study, we examined the occurrence of diatoms on two sympatric species, the native white-clawed crayfish Austropotamobius pallipes and the non-indigenous signal crayfish Pacifastacus leniusculus, coexisting in the same stream in NW Italy. We detected that signal crayfish showed a far more productive epizoic algal community than white-clawed crayfish. Microscopical analysis confirmed that non-indigenous crayfish hosted rich and diversified diatom communities while virtually no diatom was found on the native. After analyzing different hypotheses, we suggested that this significant difference can be the result of diverse crayfish behavioral habits. Because of the lack of studies investigating epibiontic diatoms on freshwater crayfish, we performed a detailed characterization on the epizoic flora, including comparisons with natural epilithic communities. The exponential diffusion of non-indigenous freshwater crayfish is a subject of greatest interest. Increasing our knowledge on their role as basibionts is definitely necessary to better understand their ecological role, also considering their influence on primary producer community and their role as vectors of algal species of concern, such as Didymosphenia geminata.     

Comparative ultrastructure of the spermatozoa of three crayfish species: Austropotamobius torrentium,Pacifastacus leniusculus,and Astacus astacus (Decapoda: Astacidae)

This study reports about the spermatozoal ultrastructure of three species of astacid crayfish, i.e., the stone crayfish Austropotamobius torrentium, signal crayfish Pacifastacus leniusculus, and noble crayfish Astacus astacus. The acrosome is a cup shaped and electron‐dense structure at the anterior of the spermatozoon and comprises three layers of differing electron densities filled with parallel filaments that extend from the base to the apical zone. The acrosome was significantly longer in A. astacus than in P. leniusculus and the shortest acrosome belongs to A. torrentium. The width of the acrosome was significantly narrower in A. torrentium than in P. leniusculus and the widest acrosome belongs to A. astacus. The L:W ratio was significantly greater in A. torrentium than in P. leniusculus and the lowest ratio belongs to A. astacus. Radial arms are visible on each side of the acrosome or nucleus in sagittal view and wrap around the spermatozoon. Each radial arm comprises a parallel bundle of microtubules arranged along the long axis within a sheath. The nucleus, with decondensed material, is located in the posterior of the cell. All parts of the spermatozoon are tightly enclosed within an extracellular capsule. Despite a well‐conserved general structure and similarity of pattern among these spermatozoa, differences in the dimensions of the acrosome within the studied species may be useful to help distinguish the different crayfish species. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

Non-native aquatic animals introductions have driven disease emergence in Europe

In this paper it is argued, using examples of disease emergence in aquatic animals in Europe, that the introduction of non-native species drives disease emergence by both extending the geographic range of parasites and pathogens and facilitating host-switching. Enteric red mouth disease and infectious haematopoietic necrosis of salmonids have extended their geographic range from North America to Europe with the import of live fish (Pimephales promelas) and rainbow trout eggs, respectively. Host-switching results in disease emergence when previously unidentified commensal organisms or known pathogen switch to new naïve hosts. The most serious endemic diseases of wild aquatic animals in Europe in recent years can be traced to the introduction of non-native species. Across Europe dramatic populations declines have occurred in native crayfish (e.g. Astacus astacus), oysters (Ostrea edulis) and eels (Anguilla anguilla), all which can be attributed, in varying degrees, to diseases (crayfish plague, Bonamia ostreae and Anguillicoloides crassus, respectively) introduced with non-native species. The severe adverse effects at a population level can be attributed to the lack of immunity in the new hosts. The impact of parasites more recently introduced to Europe, Sphaerothecum destruens (the rosette agent), and Batrachochytrium dendrobatidis, have yet to be fully determined. Both are generalists, with wide host ranges, and may present serious threats to native species. Aquaculture is the key driver for the introduction of non-native species. Most farming systems allow pathogen exchange between farmed and wild populations which underpins host-switching. Subsequently movements of animals between farms may result in the spread of newly emerged diseases. The introduction of non-native aquatic animals drives disease emergence, thus the ex-ante assessment of these hazards is severely limited. Generic risk mitigation measures (e.g. movement of disinfected eggs in place of live animals) and improved methods for rapid detection of new diseases are vital.     

Throwing the baby out with the bathwater: does laurel forest restoration remove a critical winter food supply for the critically endangered Azores bullfinch?

The invasive Clethra arborea has a dual-role in the diet of the Azores bullfinch, a critically endangered bird species endemic to the island of São Miguel (Azores, Portugal). This is a crucial winter food resource but it lowers the availability of native laurel forest species that compose most of the bird’s diet throughout the year. The removal of this and other invasive alien species is part of current laurel forest habitat restoration programmes, disregarding the impact on the Azores bullfinch population. In order to evaluate the first responses of the Azores bullfinch to habitat restoration, we studied bird diet, foraging behaviour, food availability and habitat occupancy in managed (without C. arborea) and control areas. Significant increases in the availability of native food resources in managed areas were noticeable in the diet, particularly the intake of Ilex perado ssp. azorica and Prunus lusitanica ssp. azorica flower buds. In most of the studied months birds heavily used and foraged in managed over control areas. The one exception was in December, when a resource-gap occurred in managed areas, which may be overcome in the short-term due to re-establishment of native plants following removal of invasive aliens.     

Enhanced ecological indication based on combined planktic and benthic functional approaches in large river phytoplankton ecology

Environmental DNA (eDNA) is a powerful method for assessing the presence and distribution of invasive aquatic species. We used this tool to detect and monitor several invasive crayfishes Procambarus clarkii, Orconectes limosus and Pacifastacus leniusculus present in, or likely to invade, the ponds of the Brenne Regional Natural Park. A previous study showed that the eDNA method was not very efficient in detecting P. clarkii. In the present study, we explored new improvements in the detection of invasive crayfish. We designed specific primers for each crayfish species, and set up an experimental mesocosm approach to confirm the specificity of the primers and the sampling protocol. We analysed samples taken from ponds in 2014 and 2015. We compared two qPCR protocols involving either SybrGreen or TaqMan assays. Using these same primers, we were able to detect crayfish eDNA with both assays during the mesocosm experiment. However, crayfish from field samples could only be detected by performing qPCR with a SybrGreen assay. We successfully monitored the presence of three invasive species of crayfish using eDNA. This method is a powerful tool for establishing the presence or absence of invasive species in various freshwater environments.     

Potential allelopathic effects of the tropical legume <Emphasis Type="Italic">Sesbania virgata</Emphasis> on the alien <Emphasis Type="Italic">Leucaena leucocephala</Emphasis> related to seed carbohydrate metabolism

Allelopathy has been considered a key mechanism to explain the invasiveness of some species. It is well known that invasive plants can affect native plants by producing novel allelochemicals but some exotic plant species may be also sensitive to allelochemicals released by native species, providing a tool to reduce growth and impacts of invasive exotic species. Here, using growth chamber experiments we tested the mutual potential allelopathic effects of Sesbania virgata (a native dominant species) and the alien Leucaena leucocephala seeds. S. virgata was unaffected by seed leachates of L. leucocephala, indicating that, under lab conditions, this legume presents resistance to the phytotoxic compounds produced by seeds of this alien species. In contrast, germination and seedling growth of L. leucocephala were strongly affected by the phytochemicals produced by seeds of S. virgata. A delay in endospermic mobilization of storage carbohydrates (raffinose-family oligosaccharides and galactomannan) was observed in the alien species. These potential allelopathic effects could not be attributed sole to the presence neither of the phytoxic catechin nor of ABA in seed leachates of S. virgata. Our findings indicate that the in vitro behavior of S. virgata is consistent with its aggressiveness in natural environment and suggest sesbanimide as a potential candidate as implicated in the noxious effects of S. virgata on the alien species.     

Patterns of microbial food webs in Mediterranean shallow lakes with contrasting nutrient levels and predation pressures

Hygraula nitens is a New Zealand native moth with aquatic larvae that feed on submerged aquatic plants. The larvae have been mainly observed using native Potamogeton and Myriophyllum species as a food source, although some studies reported larvae feeding on the alien macrophytes Hydrilla verticillata, Lagarosiphon major and Ceratophyllum demersum. Experimental mesocosm studies showed larvae had a major effect on H. verticillata, C. demersum, L. major, Elodea canadensis and Egeria densa. In both no choice and choice experiments H. nitens larvae showed a clear preference for and the highest consumption of C. demersum, while the native macrophyte Myriophyllum triphyllum ranked fourth out of five alien and two native plant species, indicating a preference of the larvae for alien macrophytes. Additional choice experiments using C. demersum, sampled from different waters in NZ, illustrated that there was a clear difference in H. nitens preference for plants based on their source. However although C. demersum had the lowest leaf dry matter content (LDMC) compared with the other macrophytes, neither the LDMC nor leaf carbon, nitrogen, phosphorus or total phenolic contents alone could explain the preferences of H. nitens, and we conclude that food choice is based on a combination of these and/or additional factors.     

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

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

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

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

Morphological and molecular-genetic distinctions between adult mosquitoes <Emphasis Type="Italic">Culex torrentium</Emphasis> Martini and <Emphasis Type="Italic">C. pipiens</Emphasis> Linnaeus (Diptera,Culicidae) from Moscow Province

Morphological, biological, and molecular-genetic characteristics of Culex pipiens and C. torrentium, collected from two sites in Moscow and five sites in Moscow Province, were studied. Our results demonstrated the absence of any differences between females of these species in the R ₂/R ₂₊₃ ratio. Figures and photographs of the male genitalia are given. Differences between the species in the mDNA cytochrome oxydase I gene and the 1TS2 region of the rDNA were revealed. 90–100% of C. pipiens and 0% of C. torrentium were infested with the endosymbiotic bacterium Wolbachia pipientis.