Stable isotope analysis reveals habitat-driven dietary niches of Lepus europaeus /

Understanding the trophic ecology of the European brown hare (Lepus europaeus) is essential for its conservation in intensifying agricultural landscapes. To explore dietary niches across habitats, sexes, and age groups, we applied stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) in hair samples from 151 hares collected in Lithuania and Poland from 2023 to 2025. δ13C and δ15N values varied significantly by country and habitat, but not by sex or age. Lithuanian hares exhibited lower δ13C values and a wider isotopic niche, reflecting more diverse foraging in heterogeneous habitats. In contrast, Polish hares from uniform orchard landscapes showed higher δ13C enrichment and narrower isotopic ranges, indicating greater dietary specialization on cultivated plants. Temporal variation was minimal, and isotopic overlap among months and years was high. These results suggest that habitat heterogeneity, rather than demographic factors, drives dietary flexibility in L. europaeus. Thus, stable isotope analysis provides a powerful tool for linking agricultural land use with trophic niche breadth in farmland mammals. Promoting mixed cropping systems, permanent vegetation, and structurally diverse habitats could improve food quality and support the recovery of declining hare populations

Comparison of historic and novel data reveals higher contemporary diversity of trematode metacercariae in freshwater fish /

Trematode metacercariae are the most abundant and frequently encountered helminths in freshwater fish. Yet, accurate species identification remains challenging, potentially leading to an underestimation of trematode diversity. Using data from parasitological examinations of 1,030 fish (47 species) collected from diverse freshwater habitats in Lithuania (2022–2024), we assessed the contemporary diversity of trematode metacercariae, host associations, microhabitat preferences, and changes in diversity patterns and transmission dynamics. Through integrated morphological and molecular techniques, we identified metacercariae belonging to 51 species from eight families, more than doubling previously reported diversity (25 species). While trematode family composition remained largely unchanged – the Diplostomidae and Strigeidae remained the most diverse families – notable differences were observed at the species level. Metacercariae of the Echinochasmidae and Echinostomatidae were detected for the first time, while previously reported Clinostomidae were absent. Fish of the Leuciscidae hosted the highest trematode diversity. Host specificity of metacercariae was generally low, with most species being euryxenous. At the microhabitat level, eyes harboured the highest number of species, while muscles showed the highest metacercarial density. Notably, we detected species first genetically characterised in North America (Echinoparyphium sp. 2 and Ichthyocotylurus sp. 2) and species potentially belonging to the genus Neogogatea, previously known only from Asia and North America, highlighting potential invasion risks and suggesting that European trematode diversity remains substantially underestimated. Future efforts should obtain molecular data from correctly identified adult specimens to resolve the identity of species currently identified only to the genus or family level, thereby enabling assessment of their geographical distributions and ecological roles

Decryption of amphipod cryptic species: Ecological differentiation of syntopic lineages of a Gammarus species complex /

Cryptic species represent an ever-increasing proportion of discovered biological diversity. Thus, the number of observations of cryptic species co-occurring in syntopy also increases, raising the question of mechanisms facilitating this phenomenon. Gammarus fossarum is a widespread, ecologically important, and diversified cryptic species complex with dozens of deeply divergent lineages of Miocene origin, some of which have been observed in syntopy in its European range. We used a multifaceted approach to study the ecology of two syntopic, genetically differentiated G. fossarum lineages in the stable environment of a calcareous spring fen. We investigated the effects of spatial distribution of sampling sites and local environmental factors (water chemistry, substrate composition) on the fine-scale distribution of the two lineages, together with their trophic ecology (δ13C, δ15N and gut content analysis). Moreover, we assessed functional morphological differentiation of the lineages, and compared identification based on mitochondrial DNA with variation at three nuclear markers to confirm their reproductive isolation. Small-scale syntopy of both lineages prevailed across the studied locality, having been observed at 14 out of 15 sampling spots. Lineage ratios varied within the spring fen; they were significantly affected by spatial proximity between the sampling spots, but not by local environmental conditions. The two lineages significantly differed in body size as well as trophic niche. However, they were essentially morphologically indistinguishable, although significant shifts were observed in a few phenotypic traits mainly related to feeding. The lack of nuclear allele sharing confirmed the existence of a strong reproductive barrier between them. The two studied G. fossarum lineages are reproductively isolated species that significantly differ in trophic ecology and body size in syntopy. Their local coexistence may thus be facilitated by trophic niche differentiation due to alternative resource use. Our results add to the growing body of evidence that morphologically cryptic species may not be functionally fully equivalent, indicating that cryptic species complexes may be more ecologically differentiated than currently known

Exploring potential distribution and environmental preferences of three species of Dicranomyia (Diptera: Limoniidae: Limoniinae) across the Western Palaearctic realm using Maxent /

Species distribution models were built for three short-palped crane fly species of the genus Dicranomyia: Dicranomyia affinis, Dicranomyia chorea, and Dicranomyia mitis. The main objective of this study was to assess potential habitat suitability in undersampled regions and explore differences in environmental space. Dicranomyia affinis was historically considered a variety of Dicranomyia mitis due to their morphological similarity. In contrast, Dicranomyia chorea is a widespread species. The biology and ecology of these species remain poorly understood. Models were developed using Maxent, a widely used tool. Our results indicate that Dicranomyia affinis and Dicranomyia chorea share highly similar predicted habitat suitability, with high suitability across the Mediterranean, Central, and Northern Europe, moderate suitability in Eastern Europe, and low suitability in Central Asia. In contrast, Dicranomyia mitis is predicted to have greater habitat suitability in Eastern Europe and Scandinavia, with lower suitability in Mediterranean regions. Analysis of variable importance revealed possible ecological differences between the species. While climatic factors primarily influenced the models for Dicranomyia affinis and Dicranomyia chorea, Dicranomyia mitis was more strongly influenced by the variable pH. These findings may provide insights into potential distributions in undersampled areas and improve our understanding of the species’ ecology

Divergent trends in insect disturbance across Europe's temperate and boreal forests /

Ongoing shifts in climate and land use have altered interactions between trees and insect herbivores, changing biotic disturbance regimes. However, as these changes are complex and vary across host species, insect taxa, and feeding guilds, they remain poorly understood. We compiled annual records of forest insect disturbance from 15 countries in temperate and boreal Europe, spanning the period from 2000 to 2022. The dataset comprises 1361 time series characterizing the dynamics of 50 herbivorous insects. We used this dataset to test whether insect disturbance has systematically changed during the 23-year period across host trees and feeding guilds, whether it varies along latitudinal and climatic gradients, and whether synchrony exists among species in the same guild or among species sharing the same host. Since 2000, borer disturbance was predominantly concentrated on gymnosperms, while defoliators impacted gymnosperms and angiosperms more evenly. While 85.8% of gymnosperm disturbance was inflicted by a single species, Ips typographus, the majority of disturbances to angiosperms were caused by six different species. Borer impact on gymnosperms has increased in the 21st century, while defoliator impact has decreased across both clades. In contrast to diverging temporal trends, disturbance was consistently greater in warmer and drier conditions across feeding guilds and host types. We identified significant synchrony in insect disturbance within host types and feeding guilds but not between these groups, suggesting shared drivers within guilds and host types. Increasing insect disturbance to gymnosperms may catalyze adaptive transformations in Europe's forests, promoting a shift from historical conifer-dominated management to broadleaved trees, which are less affected by insect herbivores. Our findings reveal a diversity of trends in insect herbivory, underscoring the need to strengthen monitoring and research in order to better understand underlying mechanisms and identify emerging threats that may not be apparent in currently available data

Joining application of unmanned aerial vehicle imagery with GIS for monitoring of soft cliff linear habitats /

In the coastal zone, two types of habitats—linear and areal—are distinguished. The main differences between both types are their shape and structure and the hydro- and litho-dynamic, salinity, and ecological gradients. Studying linear littoral habitats is essential for interpreting the ’coastal squeeze’ effect. The study’s main objective was to assess short-term behavior of soft cliffs as littoral linear habitats during calm season storm events in the example of the Olandų Kepurė cliff, located on a peri-urban protected seashore (Baltic Sea, Lithuania). The approach combined the surveillance of the cliff using unmanned aerial vehicles (UAVs) with the data analysis using an ArcGIS algorithm specially adjusted for linear habitats. The authors discerned two short-term behavior forms—cliff base cavities and scarp slumps. The scarp slumps are more widely spread. It is particularly noticeable at the beginning of the spring–summer period when the difference between the occurrence of both forms is 3.5 times. In contrast, cliff base cavities proliferate in spring. This phenomenon might be related to a seasonal Baltic Sea level rise. The main conclusion is that 55 m long cliff cells are optimal for analyzing short-term cliff behavior using UAV and GIS

Variation in odour profiles of cauliflower, curly kale and broccoli (Brassica oleracea L.) cultivars is affected more by genotype rather than herbivore feeding /

Volatile plant compounds are essential for host plant selection by herbivores and particularly important for the behaviour of parasitoids seeking larvae in which to lay eggs. Headspace extracts were collected from intact plants of four Brassica oleracea genotypes, as well as from plants damaged by larvae of Mamestra brassicae or Pieris rapae. In total, 52 volatiles present in the headspaces of four genotypes were selected for multivariate analyses. The most abundant groups of volatiles were terpenes and esters, represented by 20 and 14 compounds, respectively. The qualitative and quantitative differences in odour profiles between the four genotypes were sufficient to differentiate between groups using multivariate analysis techniques. The most distinct volatile blends originated from curly kale, followed by cabbage, cauliflower and broccoli. Multivariate analysis revealed that genotypes affected the composition of the volatile blends to a large extent compared to the herbivore damage by the different species tested. In curly kale, broccoli and cauliflower, the differences in odour bouquets were more expressed between plants with and without active feeding, independent of the herbivore identity, while in cabbage, larger differences were observed between odour profiles with different herbivore feedings, independent of whether the herbivore was present or removed

Effect of phenological stage and leaf age on changes of chlorophyll and carotenoid contents in some weeds and invasive species /

Potential sources of chlorophyll, widely used in the pharmaceutical and food industries, could be invasive species and weeds. The aim of the study was to estimate the effect of vegetation period and leaf age on changes of chlorophyll and carotenoid contents in leaves of six widespread plant species of four different families, as well as in the weed Urtica dioica as a “comparative” species. Plants were growing under the same environmental conditions, and chlorophylls and carotenoids were analyzed spectrophotometrically every two weeks from May to September. Average total chlorophyll (a + b) content only in leaves of Lamium album and Aegopodium podagraria was lower than in Urtica dioica and significantly differed from their content in Leonurus cardiaca and Agrimonia eupatoria. Total chlorophyll (a + b) content in leaves of common native Pastinaca sativa and very invasive Solidago canadensis was also higher or very similar to that of Urtica dioica. The highest amount of green pigments in all species was found at the budding and/or flowering period. Unlike other species, variation of total chlorophyll (a + b) in Leonurus cardiaca was little, and chlorophyll a/b ratio was lower than 2:1 during the vegetation period. In contrast to total chlorophyll (a + b), total carotenoid was higher in young leaves

Scent of death: Emission and behavioral role of 1-nonene in entomopathogenic nematode Steinernema kraussei /

Entomopathogenic nematodes (EPNs) provide a natural alternative to synthetic pesticides for pest control. Understanding how EPNs respond to volatile cues including those released by infected cadavers is crucial for determining the behavior control necessary for improving their effectiveness. In this study, we tested the response of Steinernema kraussei, a cruiser foraging species, to 1-nonene. Additionally, we analyzed the emission dynamics of this compound from Galleria mellonella larvae infected by three different EPN species: S. kraussei, S. carpocapsae, and S. feltiae. Concentrations of 1-nonene at 20 mM and above elicited a repellent behavior in S. kraussei. Ethanol, used as a solvent for 1-nonene, was attractive to this EPN at high concentrations only. The emission of 1-nonene was the lowest from larvae infected by S. feltiae compared to those infected by the other two species. Larvae infected with S. kraussei released 15 times more 1-nonene than those infected with S. feltiae, while larvae infected with S. carpocapsae released 76 times more than those infected with S. feltiae and 5 times more than those infected with S. kraussei. Comparing our findings to previous research behavioral responses to environmental compounds (ethanol and 1-nonene) suggest that EPNs with cruiser (S. kraussei) and intermediate (S. feltiae) foraging strategies show similar responses, distinct from those of ambusher’s (S. carpocapsae)