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Hybridization with introduced or invasive species is a major threat and driver of population declines in native salmonids. The rainbow trout (Oncorhynchus mykiss) is a major introduced and invasive species, often establishing entrenched naturalized populations. Here, we characterize population genetic variation of naturalized rainbow trout in a subset of Lake Tahoe tributaries to assess potential homing of rainbow trout to specific streams for spawning, thereby informing native Lahontan cutthroat trout (Oncorhynchus clarkii henshawi) reintroduction. Diploid, reproductively viable rainbow trout of commonly raised hatchery strains were stocked into Lake Tahoe from the late 1800s until the early 2000s by California and Nevada fish and wildlife agencies. Since 2007, however, triploid individuals comprise the bulk of rainbow trout planted. Despite dispersal from stocking locations across regions, our analyses revealed variation in population differentiation among tributaries, with individuals from spatially proximate streams clustering across multiple population genetic analyses. Although subtle, we detected evidence for genetic differentiation among tributaries from the southern, western, and northern regions, including surprising structure involving a single tributary. These results illustrate the extent of differentiation within and among streams and could inform possibilities for and implications of rainbow trout removal and Lahontan cutthroat trout reintroduction into its historical habitat. [ABSTRACT FROM AUTHOR]

Aims: Although litter decomposition is closely linked to soil biochemical processes, the non-additive effects of litter mixing on soil C:N:P stoichiometry and the factors that regulate it have been rarely studied. Methods: In this study, an in situ foliar litter decomposition experiment examined the effects of mixtures of the foliar litter of Eucalyptus urophylla × grandis with five native tree species (Acacia crassicarpa, Castanopsis hystrix, Michelia macclurei, Magnolia sumatrana and Mytilaria laosensis) in subtropical China. We investigated the decomposition and element release dynamics of single and mixed foliar litters, their non-additive effects on soil C:N:P stoichiometry, and the potential factors regulating this non-additive effect. Results: Our results show that foliar litter mixing promoted mass loss and element release, with less mass remaining for one mixture. The magnitude of the non-additive effects of decomposing mixed foliar litter on mass remaining, element release, and soil C:N:P stoichiometry varied by litter type. Specifically, antagonistic effects were common for mass remaining (accounting for 10.0% of all cases), the release of N (16.7%) and N:P (10.0%) of mixed foliar litter, and soil C:N (13.3%). Synergistic effects were common for the release of C (23.3%), P (10.0%), C:N (23.3%), C:P (26.7%) of mixed foliar litter, and C (20.0%), N (16.7%), P (16.7%), C:P (13.3%), N:P (10.0%) of soil. Mixing the foliar litter of Eucalyptus with some species had significant synergistic effects on soil N and N:P, whereas mixing it with other species had significant antagonistic effects on soil C:P and N:P. Conclusions: Overall, foliar litter mixtures affected soil C:N:P stoichiometry in non-additive ways, and the magnitude and direction of these effects were jointly regulated by edaphic factors, initial litter chemical traits, and the presence of an invasive species, Eucalyptus. [ABSTRACT FROM AUTHOR]

Both the identity and prevalence of parasitoid dipterans associated with bumble bees (Bombus spp.) in southern South America are little known. Between 2009 and 2017, a total of 2978 bumble bees were individually collected in 63 localities from 11 provinces of the country. After dissections, the presence of parasitoids was observed in the native bumble bees Bombus pauloensis, B. bellicosus, B. opifex, and B. brasiliensis, plus in the exotic invasive species B. terrestris. A combination of both morphological and molecular analysis based on the COI gene allowed the isolation of two species of Physocephala (Conopidae) and one of Helicobia (Sarcophagidae), expanding their host range and geographic distribution. The second instar larva of Helicobia aurescens is described. [ABSTRACT FROM AUTHOR]

Non-native species have invaded most ecosystems and methods are needed to manage them, especially in locations with sensitive species where they cannot be easily extirpated. Gillnetting for invasive lake trout [Salvelinus namaycush (Walbaum, 1792)] in Yellowstone Lake, Yellowstone National Park, USA began in 1995 and their carcasses are deposited into deep areas. This suppression method was recently supplemented by adding carcasses to shallow (< 20 m) spawning sites during the autumn spawning period to decrease dissolved oxygen through decomposition, suffocating lake trout embryos. We measured ammonium concentrations (shallow and deep sites), algal biomass, and ammonium uptake by phytoplankton and periphyton (shallow sites only) to investigate the degree to which carcasses caused bottom-up effects. Ammonium concentrations increased in autumn and were higher at deep sites than shallow sites. Algal biomass and ammonium uptake did not increase after adding carcasses, suggesting minimal effects. Periphyton biomass was 9 times higher than phytoplankton, but phytoplankton demanded 4.5 times more ammonium. Returning lake trout carcasses to deep areas of the lake may cause a second algal bloom. Assessing how novel management techniques alter the environment helps managers develop the most successful mitigation strategies that are effective without causing adverse effects to other portions of the ecosystem. [ABSTRACT FROM AUTHOR]

Successful aquatic biological invasions are often dependent on human vectors. The Chinese pond mussel Sinanodonta woodiana is a fast-growing, high-filtering, and highly fecund unionid bivalve that has expanded rapidly throughout Europe in the last several decades. Human-mediated vectors such as fish aquaculture and pet shop trade are believed to be primary drivers of the mussel's spread, but the specific dispersal pathways of S. woodiana remain unclear. We analyzed eleven microsatellites in 245 S. woodiana individuals from seven wild populations and three pet shops to assess genetic relatedness potential sources, and dispersal pathways of S. woodiana in Bavaria, Germany. Wild populations shared a single mitochondrial haplotype present in all European populations and shop-sourced individuals were genetically similar to wild populations. Only one wild population was structurally different than all other populations, which may be explained by its dispersal trajectory. Our results provide the first genetically informed insights into S. woodiana dispersal in the context of human activity. We underscore the value of genetic tools in invasive species management, which can uncover patterns of dispersal even on local scales. [ABSTRACT FROM AUTHOR]

The northern giant hornet Vespa mandarinia (NGH) is a voracious predator of other insect species, including honey bees. NGH's native range spans subtropical and temperate regions across much of east and southeast Asia and, in 2019, exotic populations of the species were discovered in North America. Despite this broad range and invasive potential, investigation of the population genomic structure of NGH across its native and introduced ranges has thus far been limited to a small number of mitochondrial samples. Here, we present analyses of genomic data from NGH individuals collected across the species' native range and from exotic individuals collected in North America. We provide the first survey of whole-genome population variation for any hornet species, covering this species' native and invasive ranges, and in doing so confirm likely origins in Japan and South Korea for the two introductions. We additionally show that, while this introduced population exhibited strongly elevated levels of inbreeding, these signatures of inbreeding are also present in some long-standing native populations, which may indicate that inbreeding depression alone is insufficient to prevent the persistence of NGH populations. As well as highlighting the importance of ongoing monitoring and eradication efforts to limit the spread of this species outside of its natural range, our data will serve as a foundational database for future genomic studies into introduced hornet populations. [ABSTRACT FROM AUTHOR]

The ability of non-native species to successfully invade new ecosystems sometimes involves evolutionary processes such as hybridization. Hybridization can produce individuals with superior traits that give them a competitive advantage over their parent species, allowing for rapid spread. Here we assess growth, functional morphology, and species interactions between two non-native beachgrass species (Ammophila arenaria and A. breviligulata) and their recently discovered hybrid (A. arenaria × A. breviligulata) on the U.S. Pacific Northwest coast. We asked whether the hybrid beachgrass differs from its parent species in morphology and growth, whether it competes with its parent species, and, if so, what are the potential mechanisms of competition. Plant taxa were grown in low- and high-density monocultures and in two-way interactions in a common garden environment. We show that the hybrid grew taller and more densely, with greater total biomass, than either parent species. The hybrid was also the better competitor, resulting in the model prediction of competitive exclusion against A. breviligulata and, depending on its relative abundance, A. arenaria. The hybrid displays a mixed 'guerilla–phalanx' growth form that allows it to spread laterally and achieve high shoot densities, giving it a competitive advantage. Given the current dominance of A. breviligulata compared to A. arenaria in most of the region where these taxa co-occur, we suggest that the hybrid will grow, compete, and spread quickly with potentially widespread consequences for the two non-native Ammophila congeners and the dunes they build. [ABSTRACT FROM AUTHOR]

Dispersal influences many key aspects of plant ecology at both fine- and broad scales. However, dispersal events are challenging to quantify as they are difficult to observe and measure accurately, despite the importance of understanding species' dispersal capacity. In this study, we quantified dispersal estimates for the dominant vascular flora of sub-Antarctic Marion Island, using a mechanistic model to estimate dispersal potential via anemochory and standardized experiments that simulate dispersal events via zoochory, human activity, and thalassochory, to test if dispersal capacity correlates to contemporary range expansion of the island's native and alien species. Our results demonstrate the broad range of dispersal potential in the island's flora and represent the first quantification of the dispersal potential (via multiple vectors) of the dominant vascular flora in the sub-Antarctic. Dispersal potential was not related to range expansion rates of native or alien species, suggesting that other mechanisms are responsible for the variation observed in species range expansion rates. Although this finding contradicts expectations and evidence from some other studies, it is consistent with research conducted in alpine regions (which may be climatically and physiognomically similar to this sub-Antarctic study site) where factors such as demography and competition are more important predictors of species range expansion than their dispersal ability, dispersal syndromes, or dispersal-related traits. [ABSTRACT FROM AUTHOR]

Non-indigenous species (NIS) establish and thrive on floating artificial substrata along mid-latitude shores, which might serve as propagule reservoirs and stepping stones for their dispersal. However, often, the NIS are not able to colonize the adjacent seafloor, where high predation pressure by benthic predators might inhibit them. To test this hypothesis, we quantified and compared consumption rates of standardized bait (squidpops) in four water depth zones (sea surface, sub-surface, midwaters, seafloor) in five representative regions in the Southeast Pacific, covering oceanic Rapa Nui (Easter Island; 27°S, 109°W; November 2022) as well as the Chilean continental coast (29–41°S, 71–73°W; March–June 2022). We found a strong overall effect of water zonation, with significant bait consumption being limited to the seafloor and occurring only sporadically in other depth zones. Consumption frequencies also differed between experimental regions but were not influenced by latitude or mean sea surface temperature. An analogous experiment with the NIS Ciona robusta, conducted at one sampling site, showed that the occurrence or absence of predation per site and water depth zone, but not the exact consumption rates, concurred between both bait types. Our results confirm that predation in SE Pacific temperate shallow waters mainly depends on benthic predators that cannot reach higher zones of the water column. These findings have far-reaching implications, as they indicate that predation rates in mid-latitude systems might be underestimated through commonly used water column-based experiments. For a comprehensive estimation of predation pressure in a given system, future studies should consider differences between vertical water zones. [ABSTRACT FROM AUTHOR]

Dominant vegetation in many ecosystems is an integral component of structure and habitat. In many drylands, native shrubs function as foundation species that benefit other plants and animals. However, invasive exotic plant species can comprise a significant proportion of the vegetation. In Central California drylands, the facilitative shrub Ephedra californica and the invasive Bromus rubens are widely dispersed and common. Using comprehensive survey data structured by shrub and open gaps for the region, we compared network structure with and without this native shrub canopy and with and without the invasive brome. The presence of the invasive brome profoundly shifted the network measure of centrality in the microsites structured by a shrub canopy (centrality scores increased from 4.3 under shrubs without brome to 6.3, i.e. a relative increase of 42%). This strongly suggests that plant species such as brome can undermine the positive and stabilizing effects of native foundation plant species provided by shrubs in drylands by changing the frequency that the remaining species connect to one another. The net proportion of positive and negative associations was consistent across all microsites (approximately 50% with a total of 14% non-random co-occurrences on average) suggesting that these plant-plant networks are rewired but not more negative. Maintaining resilience in biodiversity thus needs to capitalize on protecting native shrubs whilst also controlling invasive grass species particularly when associated with shrubs. [ABSTRACT FROM AUTHOR]

The invasive brown widow spider, Latrodectus geometricus (Araneae: Theridiidae), has spread in multiple locations around the world and, along with it, brought associated organisms such as endosymbionts. We investigated endosymbiont diversity and prevalence across putative native and invasive populations of this spider, predicting lower endosymbiont diversity across the invasive range compared to the native range. First, we characterized the microbial community in the putative native (South Africa) and invasive (Israel and the United States) ranges via high throughput 16S sequencing of 103 adult females. All specimens were dominated by reads from only 1–3 amplicon sequence variants (ASV), and most individuals were infected with an apparently uniform strain of Rhabdochlamydia. We also found Rhabdochlamydia in spider eggs, indicating that it is a maternally-inherited endosymbiont. Relatively few other ASV were detected, but included two variant Rhabdochlamydia strains and several Wolbachia, Spiroplasma and Enterobacteriaceae strains. We then diagnostically screened 118 adult female spiders from native and invasive populations specifically for Rhabdochlamydia and Wolbachia. We found Rhabdochlamydia in 86% of individuals and represented in all populations, which suggests that it is a consistent and potentially important associate of L. geometricus. Wolbachia was found at lower overall prevalence (14%) and was represented in all countries, but not all populations. In addition, we found evidence for geographic variation in endosymbiont prevalence: spiders from Israel were more likely to carry Rhabdochlamydia than those from the US and South Africa, and Wolbachia was geographically clustered in both Israel and South Africa. Characterizing endosymbiont prevalence and diversity is a first step in understanding their function inside the host and may shed light on the process of spread and population variability in cosmopolitan invasive species. [ABSTRACT FROM AUTHOR]

Here, we present history and modern distribution of Typha laxmannii in Ukraine, its ecological and phytocoenotic peculiarities. It is a perennial herbaceous plant, alien species of Asian origin which is currently spreading in the country. For the first time in the flora of Ukraine T. laxmannii (under the name T. stenophylla) was recorded in 1902 in the south of Ukraine (Kherson Oblast). The species is distributed almost throughout Ukraine, but with a majority of records in the central and western parts of Ukraine. The association Typhetum laxmannii formed by this species is common for Ukraine. Depending on the ecological and geographical conditions and floristic composition, 3 following variants in this association were identified: var. typica, var. T. latifola, and var. Schoenoplectus lacustris. Phytocoenoses of this association are distributed almost throughout the whole territory of Ukraine, but the ecological optimum of the species is observed in the South of the country, in the steppe zone, on slightly saline, well-watered substrates. Based on studies conducted in Zhytomyr Oblast in 1995–2021, the expansion rate of T. laxmannii was observed – from the South to the North – in average 16.6 ± 1.09 km·year−1. From the sites of the primary penetration of the species into the region (Forest-Steppe zone), the expansion rate of it toward to the North was significantly lower (7.7–9.0 km·year−1) compared to that in the Forest zone – Ukrainian Polissia (23.4–31.9 km·year−1). [ABSTRACT FROM AUTHOR]

The diversity of planted forest stands of the alien species Quercus rubra L. in Central Europe was studied. The northern red oak is a neophyte that has been cultivated in Europe since the seventeenth century as an ornamental as well as a useful tree. In 38 phytosociological relevés from Slovakia, Poland and the Czech Republic, we recorded a total of 223 vascular plant taxa, of which 10% were alien (with 9 invasive species). The stands were species-poor compared to the most native forests, with an average of 17 species per relevé, and most of the species had a low coverage value (around 5% on average). The representation of endangered species was very low, only three species were recorded. The dense canopy of Q. rubra and large cover of litter consisting mainly of fallen old red oak leaves affected the richness of the undergrowth. The mean cover of the tree layer was 84%, the mean cover of the shrub layer was 9% and the mean cover of the herb layer was 22%. The EuroVegChecklist Expert System assigned the relevés to five classes: Carpino-Fagetea sylvaticae, Alno glutinosae-Populetea albae, Rhamno-Prunetea, Epilobietea angustifolii and Robinietea. [ABSTRACT FROM AUTHOR]

One invasive species that decreases citrus fruit yield is the Asian citrus psyllid, Diaphorina citri Kuwayama. The psyllids are the carriers of Candidatus Liberibacter species, the pathogen that causes citrus greening disease (commonly called huanglongbing, or HLB), which is the most devastating citrus disease in the world. Originally from Southeast Asia, the Asian citrus psyllid, a highly invasive species, is spreading rapidly throughout the world. Regarding geographical distribution and population growth, climate change will aggravate its impacts on many citrus agroecosystems. However, limited information on the mechanisms underpinning the pest's invasion impedes the formulation of biosecurity risk measures. We highlight the potential suitable areas for D. citri, combining their climatic requirements, temperature and humidity, in the CLIMEX model. The model's performance was high, and it can be utilized for biosecurity risk assessment, as only 2.82% of the 496 known occurrence spots were located in areas deemed unsuitable by the model's fit. The potential habitat suitability for D. citri covered all continents except Antarctica, and the suitability ranges from unsuitable (EI < 0) to highly suitable areas (EI ≥ 30). Our model predicted suitable areas outside its known native and invaded regions, especially in Africa, South America, and Oceania. Most of these regions will remain suitable for D. citri in the future. This underscores the importance of our findings as a significant guide for future early detection and the development of climate-smart management strategies against D. citri. [ABSTRACT FROM AUTHOR]

Hybridization between native and introduced species is one of the most important reasons underlying the impact on biodiversity exerted by biological invasions and also one of the hardest to be detected. The East-Asian sika deer Cervus nippon has been introduced to several European countries, where it is known to generate fertile offspring with the congeneric native red deer C. elaphus, threatening its local populations with genetic pollution. Most studies on hybrid populations have been carried out in northern and eastern Europe, whereas introductions of this deer and their effects are still poorly known in Southern countries. In this study, we updated the distribution of sika deer in Italy, where the species has been present since at least 25 years ago, but where no formal assessment has ever been conducted. We confirm the occurrence of sika deer genes in formerly pure red-deer populations in central Italy by means of genetic analyses. Further range expansion of invasive sika deer and red × sika deer hybrids is likely to lead to further hybridisations and introgression, with implications for the genetic integrity of native red deer populations. [ABSTRACT FROM AUTHOR]

The increasing intrusion of weed species into alpine regions is an alarming threat to native floras because their strong and deep root systems cause a scarcity of nutrients to native alpine plant species. Considering the sensitive nature of alpine ecosystems, integrated weed management may be a means of preventing invasive species from going out of control. The present study investigated the allelopathic effect of Elsholtzia strobilifera on the germination and growth characteristics of Himalayan knotweed (Koenigia polystachya, syn. Polygonum polystachyum) under both field and laboratory conditions. The germination of seeds under laboratory conditions was studied by using different dilutions of hydrosol and aqueous extracts derived from E. strobilifera. In our field study, seedlings of K. polystachya were planted together with E. strobilifera in their natural habitat at a nursery. The study indicates that the seed germination and morphological parameters of seedlings were significantly inhibited by different dilutions of hydrosol and extract (reduction by 83–96% and 62–73%, respectively). In field conditions, significant inhibition in the morphological characteristics of K. polystachya was observed when grown in association with E. strobilifera. The results reveal that E. strobilifera has a significant allelopathic effect on K. polystachya. Based on the results of the present study, it can be concluded that growing plants of E. strobilifera around K. polystachya may be a novel approach to curbing the spread of the latter and suppressing the population of this species in ecologically sensitive alpine or other endangered areas. [ABSTRACT FROM AUTHOR]

The global spread of non-native species is leading to an increasing frequency of multiple co-occurring non-native species. We examined the co-occurrence of the bivalve mollusc Dreissena polymorpha (zebra mussel) with three Ponto-Caspian amphipods (Dikerogammarus villosus, Dikerogammarus haemobaphes, and Chelicorophium curvispinum) across England and Wales in association with in-situ substrate size. For all three amphipod species, substrate grain size where amphipods co-occurred with D. polymorpha was significantly finer than when recorded in isolation. Subsequently, we confirmed this via aquarium experiments. We examined the occurrence of D. villosus with D. polymorpha when present with cobbles, gravel, or sand from three population sources (co-location with abundant D. polymorpha populations, co-location with low populations, and naïve). Experiments demonstrated that D. villosus actively sought shelter on or near D. polymorpha, with their co-location being significantly more prevalent in finer grained substrates (sand > gravel > cobble). The strength of this co-location differed by population source, with those co-located with high D. polymorpha densities demonstrating a greater association. Our analyses and experiments indicate that D. polymorpha may facilitate Ponto-Caspian amphipod establishment in otherwise suboptimal locations, whereby mussel shells provide favourable structural habitat for the amphipods, analogous to the presence of coarse-grained benthic sediment. [ABSTRACT FROM AUTHOR]

Invasive alien species (IAS) pose a severe threat to global agriculture, with their impact projected to escalate due to climate change and expanding international trade. The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), a native of the Americas, has rapidly spread across various continents, causing significant damage to several food crops, especially maize. Integrated pest management (IPM) programs are vital for sustainable FAW control, combining multiple strategies for sustainable results. Over three consecutive years, 2019–20, 2020–21 and 2021–22, the field demonstrations were conducted in semiarid regions of India, testing a four-component IPM approach viz., pheromone traps, microbial, botanicals and ETL based applications of insecticides against farmers' practices (sole insecticide application). IPM implementation led to substantial reductions in FAW infestation. Furthermore, egg mass and larvae infestations were significantly lower in IPM-adopted villages compared to conventional practices. Pheromone-based monitoring demonstrated a consistent reduction in adult moth populations. The lowest technology gap (10.42), extension gap (8.33) and technology index (12.25) was recorded during 2020–21. The adoption of IPM led to increased maize yields (17.49, 12.62 and 24.87% over control), higher net returns (919, 906.20 and 992.93 USD), and favourable benefit–cost ratios (2.74, 2.39 and 2.33) compared to conventional practices respectively during 2019–20, 2020–21 and 2021–22. The economic viability of IPM strategies was evident across three consecutive years, confirming their potential for sustainable FAW management in the semiarid region of India. These strategies hold promise for adoption in other parts of the world sharing similar climatic conditions. [ABSTRACT FROM AUTHOR]

Alien woody species are successful invaders, frequently used for afforestation in regions like semi-arid lands. Shrubs and trees create important microhabitats in arid areas. Understorey vegetation in these habitats has unique species composition and coexistence. However, the impact of solitary woody species on understorey vegetation is less understood. This study evaluated the effect of native (Juniperus communis) and invasive solitary conifers (Pinus nigra) on surrounding vegetation, where individuals were relatively isolated (referred to as solitary conifers). The field study conducted in Pannonic dry sand grassland in 2018 recorded plant and lichen species presence around six selected solitary conifers. Composition and pattern of understorey vegetation were assessed using 26 m belt transects with 520 units of 5 cm × 5 cm contiguous microquadrats. Compositional diversity (CD) and the number of realized species combinations (NRC) were calculated from the circular transects. Results showed native conifer J. communis created more complex, organized microhabitats compared to alien P. nigra. CD and NRC values were significantly higher under native conifers than invasive ones (p = 0.045 and p = 0.026, respectively). Native species also had more species with a homogeneous pattern than the alien species. Alien conifers negatively affected understorey vegetation composition and pattern: some species exhibited significant gaps and clusters of occurrences along the transects under P. nigra. Based on our study, the removal of invasive woody species is necessary to sustain habitat diversity. [ABSTRACT FROM AUTHOR]

Procambarus clarkii is a notorious invasive species that has led to ecological concerns owing to its high viability and rapid reproduction. South Korea, a country exposed to a high risk of introduction of invasive species due to active international trade, has suffered from recent massive invasions by invasive species, necessitating the evaluation of potential areas requiring intensive monitoring. In this study, we developed two different types of species distribution models, CLIMEX and random forest, for P. clarkii using occurrence records from the United States. The potential distribution in the United States was predicted along coastal lines and inland regions located below 40°N latitude The model was then applied to evaluate the potential distribution in South Korea, and an ensemble map was constructed to identify the most vulnerable domestic regions. According to both models, the domestic potential distribution was highest in most areas located at low altitudes. In the ensemble model, most of the low-altitude western regions, the eastern coast, and some southern inland regions were predicted to be suitable for the distribution of P. clarkii, and a similar distribution pattern was predicted when the model was projected into the future climate. Through this study, it is possible to secure basic data that can be used for the early monitoring of the introduction and subsequent distribution of P. clarkii. [ABSTRACT FROM AUTHOR]

Herbivore performance can be impacted by elevated CO2 or insecticides. However, there is insufficient data on how invasive and native species are affected by these dual stresses. Frankliniella occidentalis and F. intonsa are economically important pests. We evaluated the direct effects of elevated CO2 on the sensitivity of thrips to spinetoram, and recorded their population fitness, as well as measured acetylcholinesterase (AChE) and cytochrome P450 (CYP450) activities in adults under short-term (3rd generation) and long-term (30th generation) exposures to these two stresses. Thrips' resistance to spinetoram was accelerated by elevated CO2, and was strongly displayed by F. occidentalis than by F. intonsa. In the 3rd generation, exposure to the two stresses significantly prolonged the longevity of adult F. occidentalis and increased its fecundity, sex ratio, and net reproductive rate (R0), whereas they only increased the fecundity of F. intonsa. Notably, the sex ratio of the former (2.15 ± 0.35) was significantly higher than that of the latter (0.65 ± 0.03). On the other hand, CYP450 activity in F. occidentalis was significantly lower than that of control. At the 30th generation, exposure to the two stresses reduced the population fitness of the two species. Additionally, the fecundity, sex ratio, R0, intrinsic rate of increase (r), and finite rate of increase (λ) of F. occidentalis were significantly higher than that of F. intonsa. Besides, AChE activities in both species were significantly lower than that of the control. We concluded that increased CO2 and spinetoram may hasten the displacement of the native species, F. intonsa by the invasive species, F. occidentalis in the future. [ABSTRACT FROM AUTHOR]

The yellow-legged hornet (Vespa velutina) is a social Hymenoptera native from Asia and an invasive species in Europe, where it was first detected in France in 2004. Since then, the species has spread across the continent invading mainland Spain and Mallorca island (Balearic archipelago, Western Mediterranean) in 2010 and 2015, respectively. Yellow-legged hornets cause severe damage to ecosystem by predating over a wide variety of pollinators including honeybees. Such a threat situation requires the development of effective management and prevention plans, which can greatly benefit from knowing both the origin and the genetic structure of the invading populations. Here we conduct a genetic study to shed light on both the origin and the phylogenetic relationships of V. velutina populations from Mallorca and mainland Spain using nuclear (STRs) and mitochondrial (cytochrome oxidase c subunit 1) gene markers. Our results show that Mallorca populations originated from invasive European specimens. Moreover, FST values, DAPC and genetic structure analysis suggest two independent incursions in the island with bottleneck and founder effect signatures. Finally, we contribute additional genetic evidence of the polyandrous behavior of this invasive species based on the inference of a mean number of mattings per nest of 3.94 (range 2–6.5). This study supports the human-mediated pathways of this species and highlights the importance of implementing effective biosecurity measures to prevent the spread of invasive alien species in island habitats. [ABSTRACT FROM AUTHOR]

Alien plants' chemical defenses against herbivores contribute to how successful they are at invading, but the defensive chemicals and their biosynthesis are sometimes poorly characterized, which limits pest management and control of invasive species. Here, the chemical defenses of invasive plant Phytolacca americana and noninvasive Phytolacca icosandra in China against generalist herbivore Spodoptera litura were compared. When plants were free from herbivores' attack, P. americana repelled S. litura females to P. icosandra. After being infested with S. litura, P. americana formed an ecological trap, which attracted S. litura to lay eggs but caused the emerged larvae to grow poorly. Further analysis found that constitutively released (Z)-3-hexenyl acetate (z3HAC) attracted S. litura females, while the herbivore-induced volatile DMNT with z3HAC repelled them. P. americana had alcohol acyltransferase genes (AATs) for z3HAC biosynthesis, but low gene expression levels of target AATs, low enzyme catalytic ability of AATs, and low level of the endogenous precursor of (Z)-3-hexen-1-ol led to undetectable levels of z3HAC. Highly enriched metabolites of organic acids and flavonoids from phenylalanine metabolism in P. americana deterred the growth of S. litura. These results suggested that invasive P. americana avoided synthesizing costly z3HAC and accumulated organic acids and flavonoids to defend against generalists, unlike its noninvasive congener, providing new insights into invasion success and pest management. [ABSTRACT FROM AUTHOR]

The Japanese beetle, Popillia japonica, is a highly polyphagous Scarabaeidae native to Japan that colonized North America and Azores in the last century and has recently invaded Italy and Switzerland. Considering its economic impact on the horticulture and turfgrass industries, this species was ranked within the EU priority pests list in 2019. According to the EU Convention on Biological Diversity, the identification of invasion routes is a pivotal aspect in an effective management program aimed at controlling invasive alien species. To reconstruct the source of introductions of this pest, we investigated the genetic variability of P. japonica in its native and invaded areas worldwide by analyzing 9 microsatellite loci and two mitochondrial genes, COX I and CytB. In its native area, P. japonica is structured into two populations: one in the southern and another in the northern-central region of Japan. A limited area within central Japan was identified as the putative source of the North American outbreak. Moreover, the ABC inference and phylogeographic reconstruction suggest that two European populations originated from two independent introductions. The Azores Islands outbreak occurred approximately 50 years ago and originated from the southeastern region of North America (For simplicity, in this paper North America refers to Canada and the USA), while the second introduction, more recently, occurred in Italy and Switzerland and originated from northeastern region of North America. [ABSTRACT FROM AUTHOR]

The red-necked longhorn beetle, Aromia bungii, is an invasive wood-boring insect that has recently invaded Europe and Japan, seriously damaging stone fruit trees in both native and invaded regions. Rose oxide, including both cis- and trans-isomers, was previously found in the volatiles produced by A. bungii adults, while the inter- and intra-specific behavioral functions of this compound remain unclear. By manually shaking the beetles, a much greater amount of rose oxide was released from the beetles, compared to that released from nondisturbed beetles. Rose oxide was further determined to be original from a white-colored secretion which was immediately sprayed by the beetles that were hand captured or squeezed by tweezers. These findings indicate that this pungent compound putatively has a role as an allomone component released from the defensive secretion by A. bungii adults when threatened, which may be an adaptive defensive strategy against the predation of natural enemies such as insectivorous birds. Y-tube olfactory assays revealed that rose oxide, at a high concentration, was significantly repellent to both sexes of A. bungii adults, suggesting that rose oxide may also have a function in the intraspecific communication of A. bungii. Considering the low price of the commercially available products, this repellent effect of rose oxide may facilitate the development of novel control strategies, such as push–pull strategy, for A. bungii. [ABSTRACT FROM AUTHOR]

Reproductive interference can lead to the exclusive distribution of species. Reports on reproductive interference between alien species are scarce, although alien species are becoming more abundant and evaluations of the interference between aliens and its influence on community structure are essential. We therefore investigated the presence of interference in two alien species of Veronica, V. cymbalaria and V. persica. Hand-pollination experiments revealed that heterospecific pollen adversely affected both species, but asymmetrically: in V. cymbalaria, it reduced the number of seeds both before and after conspecific pollination, but in V. persica it reduced the number of seeds only when it occurred before conspecific pollination. Field observation suggested that the number of seeds produced by V. cymbalaria was more influenced by the number of conspecific flowers than by the frequency of surrounding V. persica flowers. Pot experiments did not show a negative effect of heterospecific individuals on the reproductive success of focal species in either species. Observations of visiting pollinators revealed no pollinator preference between the plant species. Although we demonstrated asymmetrical reproductive interference between V. cymbalaria and V. persica, its effect in the field seemed limited. An essential factor mitigating the adverse effect of reproductive interference might be a shortage of pollinators that could facilitate interspecific pollination. We predict that further invasion of V. cymbalaria into areas where V. persica prevails is unlikely, although swift displacement of V. cymbalaria by V. persica in areas where V. cymbalaria is already established is also unlikely. [ABSTRACT FROM AUTHOR]

Background: The chilla or grey fox (Lycalopex griseus) is a native species from continental Chile and neighboring areas of Argentina. It was introduced to Isla Grande de Tierra del Fuego in 1951 and began to increase its abundance, to the chagrin of local sheep ranchers. Since 1998, its hunting has been authorized. Here we update information on the density, abundance, and activity of this fox in the Chilean sector of Tierra del Fuego Island, to evaluate its population trend since the last census conducted by the Servicio Agrícola y Ganadero (SAG) in 2007. Methods and results: We carried out two fox censuses on a 941-km transect on public roads, divided into eight routes, from October to November (spring) of 2021 and 2022, following the same design used by SAG for the fox assessments carried out from 1999 to 2007. We report a reduction of > 50% in the density and abundance of chilla foxes with respect to the 2007 estimate, which could be attributed to the interference by free-ranging dogs (Canis lupus familiaris), through restricting the use of space by the fox, while transmitting diseases and parasites, and to human hunting pressure and vehicle collisions. Discussion: The chilla fox decline highlights the need for an in-depth study to determine the ecological and socioeconomic impact of this exotic species on the ecosystems of Tierra del Fuego Island and the desirability of its management, if needed. [ABSTRACT FROM AUTHOR]

Mosquitoes are primary vectors of pathogens impacting humans, wildlife, and livestock. Among them, the Asian tiger mosquito, Aedes albopictus, stands out as an invasive species with a global distribution, having established populations on every continent except Antarctica. Recent findings incriminate Ae. albopictus in the local transmission of several pathogens causing human diseases, including dengue, chikungunya, and Zika viruses and worm parasites as Dirofilaria. In Spain, the establishment of Ae. albopictus occurred in 2004 and it rapidly expanded, currently reaching southern provinces and creating novel epidemiological scenarios in recently invaded areas. In this study, we conducted captures of Ae. albopictus from May to November 2022 in two provinces, Granada and Malaga, situated near the current edge of the species' expanding range in Spain. The objective was to identify the primary factors influencing their captures in these regions. Mosquitoes were captured using BG-Sentinel traps baited with CO2 and BG-Lure, and miniature CDC-UV traps in five different localities. Our findings underscore the influence of both extrinsic factors, such as locality, and intrinsic factors, including mosquito sex, on the abundance of captured Ae. albopictus. A higher abundance of Ae. albopictus was observed in the Malaga province compared to localities in the Granada province. Furthermore, similar numbers of Ae. albopictus mosquitoes were captured in more urbanized areas of Granada, while the lowest counts were recorded in the less urbanized area. These results were compared to captures of another common species in the area, specifically Culex pipiens. Overall, these results represent the first monitoring of invasive Ae. albopictus in the area and are discussed in the light of the potential importance of the species as a nuisance for humans and vectors of pathogens of public health relevance. [ABSTRACT FROM AUTHOR]

In recent years, introduced synanthropic species of the order Zygentoma (especially Ctenolepisma longicaudatum and C. calvum) have begun to spread in Central Europe. The two above-mentioned non-native species of silverfish have also recently been confirmed in Slovakia. This paper aims to comment on the occurrence of the two non-native species in Slovakia, to compile an identification key for all (i.e. also native) Slovak silverfish species and establish local species names. [ABSTRACT FROM AUTHOR]

The zooplankton of five estuaries of the Basque coast (southeast Bay of Biscay) was surveyed in summer 2019 to check the intraregional spread of exotic species and analyse the cross-estuary differences in brackish and neritic communities related to the arrival of exotic species and the summertime geographic gradient of water temperature. Results revealed that all the studied estuaries have been colonized by Oithona davisae but not by Acartia tonsa and Pseudodiaptomus marinus. Environmental constraints due to estuarine hydrological features partly explained such differences, and the role of secondary spread opportunities remained less clear. Cross-estuary differences in the brackish community mainly reflected changes in the dominance of the native species Acartia bifilosa relative to different exotic copepod species. The neritic holoplankton differed in the contribution of thermophilic species in agreement with the thermal west–east increase of surface water temperature in the inner Bay of Biscay in summer. The detection of large numbers of larvae of the exotic crab Rhithropanopeus harrisii only in one of the estuaries highlighted the role of exotic benthic species in enhancing intraregional differences in estuarine meroplankton. Differences in the dominance of neritic or brackish species as a function of salinity and distance from coastline were also explored. [ABSTRACT FROM AUTHOR]

The trophic niche of invasive species can vary overtime because of different processes related to ecological opportunity and invader activity that condition biological interactions with the native biodiversity. We conducted an annual-based survey of the trophic niche of the mysid Hemimysisanomala in the largest European peri-alpine lake by combining molecular and isotope analyses. We hypothesized that the population trophic niche width would vary seasonally, expanding in warm periods due to greater ecological opportunities and higher mysid metabolic activity. Molecular analyses identified a diversified set of prey throughout the year ranging from autotrophic protists to zooplankton and converged with isotope analyses to support the diet seasonality hypothesis of H.anomala with wider trophic niches and, in a lower extent, richer diets in spring and summer when compared to autumn and winter. Isotope analyses also highlighted a seasonal pattern in resources used with a dominance of pelagic reliance in summer and autumn. These results underlined the significant seasonal variability in the trophic niche of this invasive mysid suggesting that future assessments of its ecological impacts should account for the temporal variations of its trophic interactions with the native biodiversity. [ABSTRACT FROM AUTHOR]

Cryptotermes havilandi (Sjöstedt, 1900) (Blattodea: Isoptera: Kalotermitidae) is an important pest of wood worldwide. Incorporating morphology and molecular analysis, we present here the first record of this species in natural ecosystems inserted in the wettest sectors of the semiarid region of northeastern Brazil. The fact that previous extensive surveys of termites in this region (more than 30 sites) have not detected this species suggests that C. havilandi has only recently expanded its distribution. Considering that our findings were made in natural ecosystems, our results suggest that this important pest may ecologically compete with species present in Brazil, which requires specific impact studies. [ABSTRACT FROM AUTHOR]

The invasive whitefly species, Rugose Spiralling Whitefly (RSW) and Bondar's Nesting Whitefly (BNW) in coconut were reported in 2016 at Pollachi, Tamil Nadu, India and in 2019 in Kerala, India, respectively. Among the natural enemies of whiteflies, Apertochrysa astur (Banks) is predominant in coconut ecosystem. Morphology, biology, and predatory potential of A. astur have been studied. The duration of first, second, and third instar grubs of A. astur was 3.65 ± 0.109, 5.4 ± 0.184, and 6.15 ± 0.167 days when provided with RSW. Likewise, the duration of first, second, and third instar grubs of A. astur when fed with BNW averaged 3.8 ± 0.172, 6.0 ± 0.145, and 6.8 ± 0.225 days, respectively. In a laboratory experiment on the predatory potential, a third instar grub of A. astur devoured a maximum of 313 and 333 second instar nymphs of RSW and BNW, respectively. The grubs of A. astur were observed to be extremely efficient in terms of predatory potential with respect to A. rugioperculatus and P. bondari. The results supported that A. astur can be employed as an efficient biological control agent for the invasive whitefly species in the coconut ecosystem. [ABSTRACT FROM AUTHOR]

Introductions of non-native fish are intended to have positive social outcomes, although they can also result in negative environmental consequences. Recently, incidental introduction of tilapia (Oreochromis cf. niloticus) was recorded in the Kikori River, Papua New Guinea. This study investigated the abundance of Oreochromis cf. niloticus relative to native fish species in the Kikori Town market, and interviewed market vendors to gauge the local perception of Oreochromis cf. niloticus. Market data were collected over eight days with 1474 individual fish observed. Oreochromis cf. niloticus comprised 11.4% (n = 168) of fish and was the largest contributor of biomass (40.2%). Market vendors reported that Oreochromis cf. niloticus was easy to catch and sell, and ranked it highly in sale preference compared to native species. There is potential to explore export markets for Kikori River Oreochromis cf. niloticus in PNG's highland provinces to expand economic opportunities for local communities. [ABSTRACT FROM AUTHOR]

The leafhopper genus Arboridia includes several species that feed on Vitis vinifera and cause leaf chlorosis. We report the first alien Arboridia infestation in Italy in 2021 in an Apulian vineyard. To confirm the taxonomic status of the species responsible for crop damage, and reconstruct its demographic history, we barcoded individuals from Apulia together with Arboridia spp. from Crete (Greece), A. adanae from Central Turkey and other specimens of the presumed sister species, A. dalmatina from Dalmatia (Croatia). Molecular phylogenies and barcoding gap analysis identified clades not associated with sampling locations. This result is incongruent with classical specimen assignment and is further supported by morphological analyses, which did not reveal significant differences among the populations. Therefore, we propose A. dalmatina as a junior synonym of A. adanae, which would become the only grapevine-related Arboridia species in the eastern Mediterranean. To further characterise A. adanae evolution, we performed a molecular clock analysis that suggested a radiation during the Pleistocene glaciations. Finally, to assess whether the Apulian individuals carried microorganisms of agricultural relevance, we sequenced their bacterial microbiota using 16S rRNA amplicon sequencing identifying three phytopathogens not generally associated with Arboridia activities as well as Wolbachia in one Apulian haplogroup. We discuss the agricultural implications of this infestation. [ABSTRACT FROM AUTHOR]

Mosquitoes are primary vectors of pathogens impacting humans, wildlife, and livestock. Among them, the Asian tiger mosquito, Aedes albopictus, stands out as an invasive species with a global distribution, having established populations on every continent except Antarctica. Recent findings incriminate Ae. albopictus in the local transmission of several pathogens causing human diseases, including dengue, chikungunya, and Zika viruses and worm parasites as Dirofilaria. In Spain, the establishment of Ae. albopictus occurred in 2004 and it rapidly expanded, currently reaching southern provinces and creating novel epidemiological scenarios in recently invaded areas. In this study, we conducted captures of Ae. albopictus from May to November 2022 in two provinces, Granada and Malaga, situated near the current edge of the species' expanding range in Spain. The objective was to identify the primary factors influencing their captures in these regions. Mosquitoes were captured using BG-Sentinel traps baited with CO2 and BG-Lure, and miniature CDC-UV traps in five different localities. Our findings underscore the influence of both extrinsic factors, such as locality, and intrinsic factors, including mosquito sex, on the abundance of captured Ae. albopictus. A higher abundance of Ae. albopictus was observed in the Malaga province compared to localities in the Granada province. Furthermore, similar numbers of Ae. albopictus mosquitoes were captured in more urbanized areas of Granada, while the lowest counts were recorded in the less urbanized area. These results were compared to captures of another common species in the area, specifically Culex pipiens. Overall, these results represent the first monitoring of invasive Ae. albopictus in the area and are discussed in the light of the potential importance of the species as a nuisance for humans and vectors of pathogens of public health relevance. [ABSTRACT FROM AUTHOR]

Invasive ants, such as the Argentine ant, pose a severe economic and ecological threat. Despite advancements in baiting techniques, effectively managing established ant populations remains a daunting challenge, often ending in failure. Ant colonies employ behavioural immunity against pathogens, raising the question of whether ants can collectively respond to toxic baits. This study investigates whether ant colonies actively abandon palatable but harmful food sources. We provided two sucrose feeders, each generating a new foraging trail, with one transitioning to offering toxic food. Six hours later, ant activity on that path decreases, while activity on the non-toxic food and the trunk trail remains unaffected, excluding factors like population decline or satiation as reasons for the activity decline. Laboratory experiments confirmed that ants remained alive six hours after ingesting toxic food. Ant presence remains low on the toxic food path for days, gradually decreasing along the nearest section of the trunk trail. This abandonment behaviour minimises the entry of harmful food into the nest, acting as a protective social mechanism. The evasion of toxic bait-treated areas likely contributes considerably to control failures. Understanding the behavioural response to toxic baits is essential for developing effective strategies to combat invasive ant species. Ants exhibit a behavioural strategy of actively abandoning toxic foods and gradually avoiding the area to protect the colony, reducing the entry of harmful foods. This behavior threatens invasive ant control measures, since the ants abandon the baits. [ABSTRACT FROM AUTHOR]

Invasive plant species are considered one of the significant drivers of habitat loss, leading to biodiversity loss. They have also been observed to alter the local ecology, resulting in a decline of native flora. The management of invasive species is widely recognised as one of the most severe challenges to biodiversity conservation. The International Union for Conservation of Nature (IUCN) considers Lantana camara, as one of the ten worst weeds. Over time, native and indigenous species may evolve to co-exist or compete with invasive species, reducing invader fitness. It is observed that species competition fluctuates throughout environmental gradients, life phases, and abundances. Hence, competition outcome is very context-dependent. To address this challenge, we conducted a comprehensive study in three phases: we identified native species coexisting with Lantana in their natural habitats in the Doon Valley (Phase I) and documented the phenotypic traits of selected coexisting species using the Landmark BBCH (Biologische Bun-desantalt, Bundessortenamt und Chemische Industrie) scale, revealing the phenological growth patterns of selected co-existing species (Phase II). This was followed by conducting pot (Phase IIIa) and field (Phase IIIb) experiments to study the interactions between them. Notably, Justicia adhatoda, Broussonetia papyrifera, Pongamia pinnata, Urtica dioica and Bauhinia variegata demonstrated promising results in both pot and field conditions. Furthermore, after the mechanical removal of Lantana and prior to the plantation in the field experiments, four native grass species were introduced using the seed ball method. Among these, Pennisetum pedicellatum and Sorghum halpense exhibited prompt regeneration and effectively colonised the field, densely covering the cleared area. The study provides a comprehensive management plan for the restoration of Lantana affected areas through competition using native species. This study utilizes phenological assessment for native plant selection using reclamation from native grasses and proposes a management plan for combating invasive Lantana. [ABSTRACT FROM AUTHOR]

Barley straw has been used around the world for decades as a simple, cost-effective and harmless phytoplankton growth inhibition method. Although the effect of this method on algal blooms is quite well depicted, it has not yet been tested what effect it has on submerged vascular plants and if it could be used to control the spread of alien macrophytes. In this study two highly invasive plant species: Cabomba caroliniana and Elodea nuttallii were exposed to different concentration of the barley straw extract (BSE) in laboratory conditions for a duration of four weeks. In the course of the investigations, responses of 8 traits associated with growth, biomass and chlorophyll concentration of specimens to three dosages (Low, Medium, High) of BSE corresponding to concentrations: 0.03, 0.30 and 1.50 ml l−1 were analysed. The result showed that although dry mass and total length of the plants did not differ significantly between the test groups, increase in tillering and internodes number was observed for certain concentrations of the extract. This shows that if BSE has any effect on submerged macrophytes it is a positive one and thus the method is not suitable for invasive submerged aquatic plant control. Furthermore, it is recommended that before using barley straw for algae bloom control one should make sure that there are no alien aquatic submerged plants in the area that could benefit from such a treatment. [ABSTRACT FROM AUTHOR]

Amorpha fruticosa L. (Fabaceae) shows two reproductive modes, generative via seeds and vegetative via root-shoots. We studied the reproductive ability on a mixed sample collected from 6 localities in the city of Bratislava: compound fruiting per bush (12.55 ± 8.55), fruiting per bush (70.33 ± 48.04) and fruits per bush (16127.33 ± 24212.25). No significant difference was found between germination values from unpeeled fruits (achenes) and peeled fruits (seeds). Both seeds and fruits germinated very well both immediately after harvest and after storage under different temperature conditions. Peeled achenes germinated earlier. We stored seeds and fruits under different conditions, and found that the highest seed germination values were achieved by seeds stored in the dark at 22°C (60.00%) and by non-stored seeds (57.50%). The longest seedlings grew from seeds (8.48 mm) and from fruits (9.08 mm) stored at 22°C. [ABSTRACT FROM AUTHOR]

Background and aims: Interactions between species invasions and climate change have the potential to drive changes in plant communities more than either factor alone. One pathway through which these effects can occur is via changes to the rhizosphere microbial community. Invasive plants can alter these microbial communities affecting natives' abilities to compete with invaders. At the same time, climate change is leading to more frequent extreme wet and dry events. Understanding the response of plant communities to these combined global change drivers requires a comprehensive approach that assesses the relationship between plant competition and belowground rhizosphere microbial community responses. Methods: Here we use a field experiment in a California grassland with a set of six native annual forbs (i.e., wildflowers) and three invasive annual grasses to test how competition with invasive plants alters both identity and function in the native rhizosphere microbiome, and whether competition between these groups interacts with rainfall to amplify or ameliorate microbial shifts. Results: Metagenomics of rhizosphere communities revealed that drought combined with competition from invaders altered a higher number of functions and families in the native rhizosphere compared to invasive competition alone or drought alone. Watering combined with invasion led to fewer shifts. Conclusion: This suggests invasion-driven shifts in the microbial community may be involved in weakening natives' ability to cope with climate change, especially drought. Understanding the role of the microbial community under invasion and climate change may be critical to mitigating the negative effects of these interacting global change drivers on native communities. Understanding plant community response to global change drivers requires a comprehensive approach that assesses the relationship between plant competition and belowground rhizosphere microbial community responses. (a) In this work, we use a field experiment in a California grassland with a set of native forbs (purple) and invasive grasses (teal) to assess the combined effects of competition and water availability (drought, control, watered) on the rhizosphere microbiome. (b) Drought combined with competition from invaders altered the relative abundance of 36 functions (white) and 22 microbial families (blue) in the native rhizosphere compared to the effects of competition (3 functions, 16 families) or drought alone on natives (not shown: 5 functions, 0 families). (c) Additionally, regardless of watering treatment, invasive grasses sourced more of the taxonomic community in native-invasive mixes and this was exacerbated during drought. Overall, these results suggest invasion-driven shifts in the microbiome may be involved in weakening natives' ability to cope with climate change, especially drought. [ABSTRACT FROM AUTHOR]

Background and aims: Soil heterogeneity can be caused by plant-soil feedback (PSF), but little is known about how this affects plant growth and the distribution of roots. Moreover, as invasive and native plant species frequently differ in PSF and root-foraging ability, they may differ in their responses to PSF-mediated soil heterogeneity. Methods: We first conditioned soils by 16 plant species (eight confamilial pairs of invasive alien and native species). Then, we grew each species in a homogeneous treatment with unconditioned soil and in three heterogeneous treatments with four patches. In the home-soil treatment, we filled two patches with unconditioned soil and two with soil conditioned by the target species. In the foreign-soil treatment, we filled two patches with unconditioned soil and two with soil conditioned by the other species in a pair. In the home-and-foreign-soil treatment, we filled two patches with home soil and two with foreign soil. Results: Compared to the homogeneous unconditioned soil treatment, PSF negatively affected plant growth. In the heterogeneous treatment with control- and home-soil patches, biomass was reduced more strongly for the invasive species than for the native species. In the heterogeneous treatment with both home- and foreign-soil patches, root biomass of the invasive species was greater in the foreign-soil than in the home-soil patches, whereas the reverse was true for natives. Conclusion: Although invasive species suffered more from conspecific PSF, root foraging allowed them to avoid home soil. In the long term, this could help invasive species gain a competitive advantage over natives. [ABSTRACT FROM AUTHOR]

Understanding the circumstances under which insect herbivores will adopt a novel host plant is a longstanding question in basic and applied ecology. While geographic variation in host use can arise through differences in both herbivore preference and plant characteristics, there is a tendency to attribute geographic variation in host use to regional differences in herbivore preference alone. This is especially true for herbivores specialized to one or a few plant species. We compared how geographic variation in herbivore preference and host plant origin shape regional differences in host plant use by the specialized herbivore, Euphydryas phaeton. In parts of its range, E. phaeton uses only a native host, Chelone glabra, while in others, it also uses an introduced host, Plantago lanceolata. We offered female butterflies from each region the non-native host plant sourced from both regions and compared their oviposition behavior. The non-native host was almost universally rejected by butterflies in the region where only the native plant is used. In the region where butterflies use both hosts, females accepted non-native plants from their natal region twice as often as non-native plants from the other region where they are not used. Acceptance differed substantially among individual butterflies within regions but not among plants within regions. Thus, both individual preference and regional differences in both the insect and non-native host contributed to the geographic variation in different ways. These results highlight that, in addition to herbivore preference, regional differences in perceived plant suitability may be an important driver of diet breadth. [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) has been exploited as a promising strategy for pest control and also has great potential against the spotted wing drosophila (SWD) Drosophila suzukii. However, since RNAi is poorly induced in D. suzukii through the oral intake of unprotected double-stranded RNA (dsRNA), establishing a potent strategy for dsRNA delivery remains essential. In this study, we developed novel virus-like particles (VLPs) derived from the Drosophila X virus (DXV) and investigated their capability to deliver dsRNA in vitro in cultured insect cells and in vivo in live insects. First, the polyproteins of DXV fused at the C-terminus with eGFP or Myc-tag were able to self-assemble into VLPs, in a spherical shape similar to authentic virions. Then, dsRNA molecules were loaded into the DXV-VLPs by a dis-/reassembly strategy and were demonstrated to be partly sheltered from degradation in body fluids from D. suzukii. Furthermore, DXV-VLPs were able to carry the dsRNA efficiently into Drosophila S2 cells and D. suzukii adults. By targeting the essential vha26 gene in D. suzukii adult, DXV-VLP∷dsvha26 complexes could induce higher mortality (46%) and gene silencing (36%) compared with the DXV-VLP∷dsGFP, and unprotected dsvha26 (less than 17% mortality and no silencing). Taken together, as a proof-of-concept, this study suggests that insect virus-based VLPs can function as nano-vehicles for dsRNA delivery into insects and provide a tool to improve RNAi for fundamental studies and pest control. [ABSTRACT FROM AUTHOR]

The common and the German wasp, Vespula vulgaris and V. germanica, have proved to be prolific invasive species capable of degrading local ecosystems and costing invaded countries millions of dollars annually. Despite clear incentive, control strategies are yet to have any significant deleterious impact on invasive populations. Several species of arthropods are known to inhabit Vespula nests and feed upon developing larvae as either parasitoids or predators. Recent control strategies propose the use of such parasitoids as agents of biocontrol against invasive wasps (Volucella inanis in particular). Despite a general understanding of parasitoid ecology, some aspects such as prevalence, distribution, and behaviour remain limited. Here, we surveyed natural enemy prevalence in wasp nests over the period of three years and we tested larvae prey preference of two Volucella species, V. inanis and V. zonaria towards Vespula wasps. We find V. inanis to be the most prevalent of four prominent candidates for Vespid biocontrol—V. inanis, V. zonaria, Sphecophaga vesparum, and Metoecus paradoxus. Using two-choice assays, we find larvae of V. inanis to have slight yet significant prey preference for V. vulgaris larvae over V. germanica larvae, whilst V. zonaria display no preference. Furthermore, V. inanis were not averse to still predating upon V. germanica, doing so in 41% of trials. Prior exposure has no effect on the prey-preference. Our work provides experimental evidence that V. inanis is a promising candidate for biocontrol of invasive Vespula wasps, as the larvae predate on both target species of Vespula and display no exclusive preference among them. [ABSTRACT FROM AUTHOR]

The invasive mealybug Delottococcus aberiae De Lotto (Hemiptera: Pseudococcidae) has become a key pest in Mediterranean citrus. This mealybug species excretes honeydew that can be consumed by ants, which may give rise to mutualistic relationships and increase the invasibility of this exotic pest. Here, we studied the interaction between D. aberiae and ants in 16 citrus orchards located in the main citrus-growing area of Spain (Valencia) during two consecutive years. Four native ant species were observed feeding on D. aberiae honeydew, and Lasius grandis Forel (Hymenoptera: Formicidae) represented more than 95% of these ants. Lasius grandis was observed attending D. aberiae throughout the year and in all the orchard sites where the mealybug was present. Mealybug colony size had a positive effect on both relative and absolute ant-attendance by L. grandis, but these interactions varied across seasons. Moreover, we found a positive correlation between L. grandis activity and D. aberiae density in all citrus orchards. Our results suggest that the native ant L. grandis and the invasive pest D. aberiae have established a mutualistic association that promotes the establishment and accelerate the invasion of D. aberiae in Spanish citrus orchards. Further research with the aim of evaluating whether the management of this ant species can improve the control of D. aberiae in citrus would be recommended. [ABSTRACT FROM AUTHOR]

Pink salmon, Oncorhynchus gorbuscha (Walbaum, 1792), a native of the North Pacific Ocean, is an invasive fish species rapidly expanding in the North Atlantic, the adjacent waters of the Arctic Ocean, and rivers in their watersheds. We investigated the species composition of parasites and the structure of parasite communities of the introduced pink salmon in Kandalaksha Bay of the White Sea in 2021. The parasites were identified using morphological and genetic methods. A total of 14 parasite species were recorded. The core species of the parasitic fauna of the introduced pink salmon in the Kandalaksha Bay were Clistobothrium sp., ʽDiphyllobothriumʼ spp., Scolex polymorphus Rudolphi, 1819 (plerocercoids), Brachyphallus crenatus (Rudolphi, 1802), Derogenes varicus (Müller, 1784), Lecithaster salmonis Yamaguti, 1934 (adults), Anisakis simplex (Rudolphi, 1809) sensu stricto (juvenile III), and Hysterothylacium aduncum (Rudolphi, 1802) (juveniles III and IV). We provided the first evidence that the Pacific genetic lineage of A. simplex sensu stricto occurs in European marine waters. In 2021, there was a noticeable increase in the mean abundance of the third-stage juveniles of Anisakis in the White Sea pink salmon compared to the period of 1990s-early 2000s. We conclude that the pink salmon occupies the same trophic niche in the new region of its introduction as in the native range. [ABSTRACT FROM AUTHOR]

The East European vole is a facultative synanthropic species that actively spreads in the eastern part of northern Eurasia. The distribution area of the species in Irkutsk oblast has been known as a disjunct part of the range since the 1980s. Our dataset includes 98 individuals caught in 2016–2017 and 2021–2023 in the eastern segment of the species'dispersal area, where the East European vole was first discovered in the early 2010s. Animals were caught in anthropogenically transformed landscapes spanning from the outskirts of Irkutsk to kilometer 23 of the Goloustnenskii Tract; trapping in natural biotopes revealed no M. rossiaemeridionalis. Species identification was based on molecular genetic markers. Morphological and fine structural characteristics of molar teeth were studied using both light and scanning electron microscopy. The complexity of the occlusal surface, the alternation patterns of the enamel cutting edges (occlusal regularity), and the presence or absence of atypical extra elements such as prismatic folds and prisms in places of the early cricetid dental features were assessed. The estimates of the complexity and regularity patterns fell within the range of dental variability known for the continuous distribution area of the species. The atypical extra elements on molars were described in M. rossiaemeridionalis for the first time based on material coming from two trapping sites. With the maximum manifestation of these folds, a supernumerary prism, topologically corresponding to the hypoconid, is separated from the posterior lobe of the lower teeth. The distribution of lamellar and radial enamel on the supernumerary prism is not consistent with the functionally significant and evolutionarily determined distribution of enamel types on teeth of the genus Microtus. It is concluded that the studied local micropopulation exhibits the phenotypic consequences of population restoration from a small number of founders. Apparently, the species in the study area faces multiple successive cases of establishment (naturalization) in a new territory. The results obtained confirm the prospects of using dental characters for monitoring Arvicolinae species, the distribution boundaries of which are subject to significant spatial changes in the relatively short periods of time available for observation. [ABSTRACT FROM AUTHOR]

Updated information on the distribution and studied populations of T. cristatus on the eastern macro-slope of the Urals (Middle and Southern Urals) is provided. Based on tagging with recapture, the number of reproductive individuals of the populations, the sex ratio, and the morphological specificity are estimated for the first time. From the standpoint of assessing the physicochemical features of the habitat environment, possible limiting factors (thermal and moisture availability, geochemical characteristics, climate continentality, and the presence of natural enemies and invasive species) that affect the distribution and abundance of the great crested newt near the northeastern limit of the range are discussed. [ABSTRACT FROM AUTHOR]

Alien plant species regularly and simultaneously invade agricultural landscapes and ecosystems; however, the effects of co-invasion on crop production and native biodiversity have rarely been studied. Secondary metabolites produced by alien plants may be allelopathic; if they enter the soil, they may be transported by agricultural activities, negatively affecting crop yield and biodiversity. It is unknown whether substances from different alien species in combination have a greater impact on crops and wild plants than if they are from only one of the alien species. In this study, we used a set of common garden experiments to test the hypothesis that mixed extracts from two common invasive species have synergistic effects on crops and weeds (defined as all non-crop plants) in European agricultural fields compared to single-species extracts. We found that both the combined and individual extracts had detrimental effects on the seed germination, seedling growth, biomass, and photosynthetic performance of both crops and weeds. We found that the negative effect of mixed extracts was not additive and that crop plants were more strongly affected by invasive species extracts than the weeds. Our results are important for managing invasive species in unique ecosystems on agricultural land and preventing economic losses in yield production. [ABSTRACT FROM AUTHOR]