One of the main challenges of social parasitism is deceiving the host’s recognition system and thereby exploiting redirected altruistic behavior. Various chemical strategies have evolved to achieve this goal. The most widespread, used also by the obligate slave-making ants, is camouflage or mimicry of the colony odour encoded in cuticular hydrocarbon (CHC) composition. However, recent studies have shown that facultative slave-makers employ a different strategy: they manipulate the slaves’ recognition labels to make them resemble the parasite’s CHC profile. We examined the limitations of this strategy by focusing on incipient F. sanguinea colonies, where slaves are the majority. Our study revealed that callow F. sanguinea ants initially suppress their species-specific odour profile, which develops gradually over time, accompanied by an increase of the CHC amount per surface area in slave-maker workers. This allows the slaves to familiarise themselves with the parasite’s CHCs. We found that callow ants produce lower amounts of CHCs, and the relative abundance of certain compounds differs from that in older ants. Additionally, preimaginal stages of F. sanguinea ants acquire CHCs from the slaves, which are later incorporated into the recognition labels of the imagines. These findings support the proposition that the parasite’s manipulation strategy is limited by the slaves’ learning capacity, which is necessary to maintain colony cohesion. They also shed light on the selective pressures that might have led to the evolution of chemical mimicry in mature obligate slave-maker colonies. Social insects are characterized by colony-specific odours used for colony member recognition and ensuring proper targeting of altruistic behaviour. This barrier is challenged by social parasites that attempt to establish themselves in host colonies. Slave-making ants are unique in that they bring the host ants (so-called slaves) to their own nests. Like other social parasites, they use chemical mimicry by having a recognition odour similar to that of the host. However, the function of this adaptation is not clear, given that slave-makers live separately from host colonies. Our study demonstrates that in a facultative slave-making species, chemical mimicry is employed only in the initial phase of colony development when slaves constitute the majority of the slave-maker colony. This finding emphasizes the role of the slave proportion in the evolution of chemical strategies in slave-making ants.

This article discusses the general aspects of insect communication, which can be broadly subdivided into auditory, visual, and chemical. The physical and conceptual basis is given for all three communication modalities, and prominent examples are listed for each category. Intra- as well as interspecific communication are discussed for each modality as well, with the former most prominently dealing with information transfer in sexual interactions between potential mating partners, whereas the latter is predominantly, but not exclusively, found in predator-prey relationships. The article closes with a fascinating look into case studies integrating different signaling modalities to obtain a more complete view on the various types of information transferred, and an outlook into what can and should be expected from future studies in this intriguing field.

Volatile organic compounds (VOCs) emitted by deadwood are increasingly recognised as key olfactory cues used by saproxylic beetles to locate suitable substrates, yet their role during colonisation remains poorly understood. To address this, we quantified VOC emissions and beetle assemblages while experimentally disentangling the main ecological drivers of the deadwood volatilome (tree species, sun exposure). We exposed 1200 freshly cut branches of oak, beech, spruce, and pine across Central Europe. To mimic natural variation in deadwood and disturbance, bundles were either sterilised (reducing endogenous fungi), inoculated with a brown rot fungus (Fomitopsis pinicola) or a white rot fungus (Fomes fomentarius), or burned. From each bundle, we sampled 448 substances, 89 of which were identified as VOCs, and reared 134 saproxylic beetle species. Broadleaf and conifer species emitted distinct VOC profiles that matched beetle tree-type preferences. In conifers, bark beetles, longhorn beetles, and jewel beetles were associated with different chemical cues, whereas taxonomic separation was not observed in broadleafs. Although treatments altered VOC composition, they did not explain beetle colonisation. Our study shows that VOCs emitted during early decay are associated with distinct beetle assemblages. The VOC composition varied with tree species and treatments, indicating that chemical variation reflects the influence of multiple ecological factors. These findings suggest that tree-species diversity enhances chemical heterogeneity in deadwood, which is linked to broader beetle assemblages. Forest conservation efforts may therefore need to consider the role of chemical variation in deadwood, as it could influence saproxylic colonisation and biodiversity management.

Ongoing environmental change has caused significant modifications in the diversity, abundance and community composition of insects across Central Europe. Nocturnal insects, such as macro-moths, are species rich and represent a large part of insect biomass, but are underrepresented in scientific studies. In this study, we analysed long-term changes of macro-moth diversity and community composition across south-western Germany, using records from two time periods: 1970-2000 and 2001-2020 obtained at identical study sites, almost all nature reserves. Total species richness remained constant, while local species composition changed significantly. Endangered and specialized open landscape species, and those adapted to bogs and coniferous forests became less common. Thermophilic species adapted to dry mixed forests became more abundant. The macro-moth communities became considerably more uniform and are increasingly dominated by common habitat generalist species. The decline in specialized open-landscape species seems to be due to losses of formerly extensively used grassland and agricultural intensification. Species with Mediterranean core areas increased in abundance. Likely, climate and land-use change will strengthen the observed trends and continue to reshape macro-moth communities, with the potential for continued compositional homogenisation.

Ecology and habitat demand of species determine their population structure and dynamics as well as their behaviour and responses to habitat changes. Species specialised to forest ecosystems are assumed to behave differently in these ecosystems than generalist species, which also occur in open ecosystems. For assessing how species with different ecological performance thrive in a small remnant forest, we selected two butterfly species with different degrees of habitat specialisation. We conducted a mark-release-recapture study in a church forest in northern Ethiopia to investigate the population ecology of these two species. As model species we selected the forest species Junonia terea and the habitat generalist Phalantha phalantha. We found for both species that one generation was fading out in the second half of the dry season but was substituted by the onset of eclosion of a follow-up generation. This population dynamic was also supported by population size dynamics, capture probability and survival probability. Life spans were comparatively short for both species, except for some few individuals. Dispersal behaviour of P. phalantha was very low, while J. terea was more dispersive, a common feature in forest butterflies. P. phalantha preferred habitats characterised by ground cover, litter, flowering plants and little shade. It thus preferred light spots inside the forest confirming the typical ecological niche of a generalist species being more common in open habitats than in forests. No habitat preferences were obtained for the euryoecious forest species J. terea, which thus occurs virtually anywhere in wooded habitats. Our study clearly shows that the ecological performance of these two species had a significant influence on habitat selection, population dynamics, and behaviour. Our findings underline the high conservation value of still intact forest ecosystems to hold typical and highly specialized forest species.

Habitat destruction and the deterioration of habitat quality are among the main drivers causing worldwide biodiversity loss. The lowland tropical dry forests of the East African coastal region, a hotspot of endemism, have been negatively affected by anthropogenic activities over the last few centuries. Today, only small remnants of these forests with their pristine flora and fauna still exist. It is questionable to what extent the original biodiversity can persist in such small and isolated habitat remnants. Butterflies respond highly sensitively to environmental changes. In this study, we analysed butterfly community structures across a habitat mosaic consisting of natural ecosystems and anthropogenic agro-environments in southern Kenya. Butterflies were counted along line-transects in dense forest, along the forest margin, and in neighbouring pastures and orchards; several biotic and abiotic parameters were assessed for all transect sections (e.g., addressing the vegetation structure). Data collection was conducted during the rainy and dry season, as well as during the transition between both seasons. We compiled species specific traits on the butterfly species ecology, distribution, and behaviour. The obtained results revealed significant differentiation among the butterfly communities in natural forest, forest margins, and in the anthropogenic ecosystems. Although both butterfly diversity and abundance were lowest inside the natural forest, vulnerable forest specialist species occurred restricted to the forest and were absent from anthropogenic ecosystems. The butterfly communities found in the agro-environments were species-rich if compared with the natural forest ecosystem, but dominated by generalist species. From the dry to the rainy season, species numbers increased in all habitat types, but the number of individuals increased only at forest margins and in pastures. This underlines the buffering effect against drought in forests but also in orchards. In general, our data underline that no surrogate habitat exists for typical forest butterflies. This underlines the high ecological relevance of such forest remnants and confirms the necessity of strict conservation of these last remnants of lowland dry forest.

Social insects discriminate between foreigners and members of their own colony via complex olfactory cues. Although it is known that genetically distinct individuals can sometimes be accepted as nestmates, the conditions that facilitate the acquisition, maintenance, and loss of tolerance, as well as the timescales of these processes, remain incompletely understood. Here, we address this gap by studying non-nestmate discrimination in the clonal raider ant, Ooceraea biroi, which provides unparalleled experimental control over the genotype of individuals and the genotypic composition of colonies. Using a cross-fostering design with mixed-genotype colonies of wild-type and transgenically labeled individuals, we show that ants become non-aggressive specifically toward their foster genotype. This tolerance is transient, and aggression resumes after 2 weeks of being isolated from the foster colony. However, even sporadic re-exposure to individuals from the foster colony is sufficient to maintain tolerance for over a month, while the same paradigm fails to establish tolerance in the first place. This shows that non-nestmate discrimination is remarkably plastic and that, once established, tolerance toward foreigners can be maintained by only intermittent contact. These dynamics echo general principles of social learning and contact-dependent tolerance described in other social species, including humans.

The concept of space–time equivalence refers to the observation that ecological patterns might look similar when studied in space or time. It has frequently been applied in studies on environmental (mainly climate) change, where appropriate temporal data are lacking. Here, we take advantage of long-term butterfly museum records, taken from 1985 to 2022 at multiple sites from three habitat types in the northern Austrian Alps. We ask whether the pattern of species accumulation, the demographic variability, and the temporal pattern of species turnover (β-diversity) of butterflies are qualitatively and also quantitatively equivalent in space and time. A power function model of species accumulation was able to describe the long-term temporal and large-scale spatial variability of butterfly assemblages. Slopes of the species accumulation curves and β-diversity were always higher in space than in time. Average species ranks of the most frequently occurring species in space were consistently higher than those in time. Both patterns were most pronounced in ecologically more specialised species and in pastures. We conclude that habitat characteristics and heterogeneity are more important for the degree of β-diversity than species traits. We predict that increasing spatial faunal homogenisation should shift butterfly and also other arthropod assemblages towards patterns of species accumulation with similar slopes.

The ongoing global decline in insect abundance and biomass is now well documented. To what degree this decline in insect abundance and biomass causes losses in biodiversity is still unclear, mainly due to the lack of appropriate quantitative long-term studies that allow for precise estimates of richness over time. In conservation ecology, the species accumulation curve (SAC) is a common method to assess the effectiveness of protected areas and to compare richness estimates at a standardised sample size. However, extrapolation and richness estimation are only possible in cases of asymptotic convergence, which was not achieved in many studies. Here, we construct temporal series of SACs from long-term surveys (1950–2022) of Austrian butterflies and macro-moths to assess temporal trends in species richness and dominance inside and outside protected areas across an altitudinal gradient. Irrespective of altitude, we detected a trend towards increasing rarity and dominance outside PAs, but not towards decreasing total richness. These trends were less visible inside PAs, although in lowland PAs sample-size-normalised richness also decreased over time. Evenness in PAs remained constant over time and was generally higher than outside PAs. Both, protected and unprotected areas suffered from high temporal species turnover. We conclude that the Lepidoptera assemblages of our study region underwent severe and ongoing structural rearrangements with unknown consequences for the sustained occurrence of many now-rare species. Temporal series of spatial species accumulation curves are able to detect such structural changes. The protected areas of our study region succeeded in conserving assemblage structure and compositional variability. Fewer species than outside PAs became rare. However, total richness is still higher outside PAs, and negative population trends were also visible inside PAs.

Beyond their impressive repertoire of camouflage as the predominant primary defensive strategy, stick and leaf insects (Phasmatodea) can actively defend themselves chemically with deterrent substances emitted from a pair of prothoracic repellent glands. The Vietnamese Prickly Stick Insect Neohirasea catbaensis emits a conspicuous secretion when disturbed, often described as smoky, which constitutes a unique characteristic not known from any other stick and leaf insect. Here we investigate the anatomy and the chemical components of the repellent glands in this species. Via micro-computed tomography (µ-CT), we observed comparatively small sac-like glands with no ejaculatory ducts present. The anatomy of the repellent glands of both male and female is described in detail. By applying gas chromatography (GC) in combination with high-resolution accurate mass spectrometry (HRAM-MS), we found 4-vinylphenol as the major component of the secretion, accompanied by 2-methoxy-4-vinylphenol and eugenol as minor constituents. This is the first time that these molecules have been identified as repellent substances from an animal. We discuss these findings in relation to the chemical diversity and ecological function of phasmatodean repellent secretions.

Volatile organic compounds (VOCs) create invisible chemical landscapes that influence ecosystem processes. Yet whether VOC β-diversity (i.e., variability in VOC composition between patches) responds to structural heterogeneity and reflects silvicultural habitat management remains unclear. In a large field experiment, we quantified how enhanced structural beta complexity (ESBC) affects VOC β-diversity patterns and investigated potential drivers and ecological effects in temperate production forests. We sampled VOCs in ambient forest air using Tenax/Carboxen adsorbent traps at forest floor and 1 m heights across 234 treatment and control forest patches in six German regions. We analyzed VOCs via thermal desorption-gas chromatography mass-spectrometry (TD-GCMS) and examined environmental drivers including deadwood characteristics, canopy cover, tree species dissimilarity, and herb layer dissimilarity. We tested potential ecological relevance by analyzing saproxylic beetle community responses. VOC β-diversity increased significantly at 1 m height in heterogeneous forests compared to homogeneous forests, but we found no significant change at the forest floor. Deadwood volume and deadwood structural diversity, rather than canopy openness, were identified as the main drivers of increasing VOC β-diversity. Dissimilarity in beetle community composition was associated with VOC β-diversity, but only for forest floor VOCs, suggesting these chemical patterns may correlate with variables beetles respond to. Our findings suggest that volatile β-diversity represents an overlooked dimension of habitat heterogeneity, one that creates invisible chemical heterogeneity influencing inter- and intra-species interactions and ecosystem processes. We demonstrate that enhancing forest heterogeneity through deadwood retention increases both structural heterogeneity and volatile β-diversity.

The UN Decade on Ecosystem Restoration aims to stop biodiversity losses1. Approximately 60% of tropical forests have already been lost or severely degraded2, making restoration essential to achieve conservation goals. Recovery trajectories of trees have been studied intensively3,4, but a comprehensive understanding of biodiversity recovery is lacking. Here we analyse recovery trajectories across trophic levels including 16 taxonomic groups from three kingdoms in a lowland tropical forest by investigating resistance to perturbation, recovery times and return rates to old-growth forest conditions. Abundance and diversity regained more than 90% and composition approximately 75% similarity to old-growth forests within 30 years, but full recovery takes several decades. Mobile animal communities acting as seed dispersers or pollinators had high resistance levels and recovered faster than trees or tree seedlings. Return rates contributed 1-2.5 times more than resistance to the recovery times of species composition. Taxon-specific recovery times could not be explained by simple mechanisms (life-history strategies, trophic level or mobility). We show the enormous potential of protecting naturally recovering secondary forests to stop and reverse biodiversity losses.

Land management intensity shapes ecosystem service provision, socio-ecological resilience and is central to sustainable transformation. Yet most land use models emphasise economic and biophysical drivers, while socio-psychological factors influencing land managers' decisions remain underrepresented despite increasing evidence that they shape land management choices. To address this gap, we develop a generic behavioural extension for agent-based land use models, guided by the Theory of Planned Behaviour as an overarching conceptual framework. The extension integrates environmental attitudes, descriptive social norms and behavioural inertia into land managers' decisions on land management intensity. To demonstrate applicability, the extension is coupled to an existing land use modelling framework and explored in stylised settings to isolate behavioural mechanisms. Results show that socio-psychological drivers can significantly alter land management intensity shares, landscape configuration, and ecosystem service provision. Nonlinear feedbacks between these drivers, spatial resource heterogeneity, and ecosystem service demand lead to emergent dynamics that are sometimes counter-intuitive and can diverge from the agent-level decision rules. Increasing the influence of social norms generates spatial clustering and higher landscape connectivity, while feedbacks between behavioural factors can lead to path dependence, lock-in effects, and the emergence of multiple stable regimes with sharp transitions. The proposed framework demonstrates how even low levels of behavioural diversity and social interactions can reshape system-level land use outcomes and provides a reusable modelling component for incorporating socio-psychological processes into land use simulations. The approach can be integrated into other agent-based land use models and parameterised empirically in future work.

Animal microbiomes often show phylosymbiosis, a pattern in which closely related hosts harbour more similar microbial communities than distant hosts. Yet, the processes generating this pattern remain unresolved, particularly whether phylosymbiosis requires sociality and vertical microbial transmission or can emerge through host filtering from environmental microbial pools. Bees (Anthophila) provide a powerful model to test this question because their major evolutionary radiation spans diverse life histories and contrasting microbiome transmission modes. Here, we analysed gut bacterial communities from 60 bee genera worldwide (1,989 samples), spanning all major bee families, and combined comparative phylogenetic models with host traits, bacterial phylogenies and predicted functional profiles to disentangle ecological and evolutionary drivers of phylosymbiosis. We found strong phylosymbiosis across and within bee families, with host phylogeny explaining substantial variation in gut microbiome composition despite weak effects of measured host traits. Geo-environmental context also explained considerable variation, indicating interactions between evolutionary and environmental filters. Despite extensive taxonomic and phylogenetic turnover, microbial functional divergence was weaker, suggesting convergence despite compositional differentiation. Together, these results show that microbiome composition can follow host phylogeny even under predominantly environmental acquisition and that phylosymbiosis can emerge through repeated assembly of functionally conserved communities rather than strict microbial inheritance.

IntroductionHierodula is a morphologically conservative mantid genus with a complex taxonomic history and several problematic species-level concepts across its native and invaded ranges. In Iran, four nominal Hierodula species have historically been reported (H. macrostigmata, H. tenuidentata, H. transcaucasica, and “H. trimacula”), but their validity and distributions have remained uncertain due to overlapping diagnostic characters and limited molecular data. This study addresses these issues by reassessing all available Iranian material within an integrative framework.MethodsThe revision combines: Morphological examination of type and non-type material from Iran, India, Pakistan, and Oman, including detailed study of external characters and male genitalia. Mitochondrial COI barcoding of Hierodula specimens from multiple Iranian provinces and Pakistan, analyzed with Bayesian inference, maximum likelihood, and model-based genetic distance estimation. Compilation and critical validation of distributional data from museum collections, literature, and iNaturalist records, followed by mapping in QGIS.ResultsMorphological comparisons show that the holotype of H. macrostigmata and recently collected southern Iranian specimens are indistinguishable from H. coarctata in forewing stigma, pronotal shape, and male genitalia, supporting their synonymy. COI phylogenies and TN93 genetic distances recover two deeply divergent, well-supported clades corresponding to H. coarctata and the H. tenuidentata complex, with minimal intraspecific divergence and no separation between Iranian “H. macrostigmata” and Indian/Pakistani H. coarctata. Re-examination of specimens and literature demonstrates that records of “Hierodula/Sphodromantis trimacula” from Iran lack verifiable material, while male genital characters place the species unambiguously in Sphodromantis and confirm its absence from the Iranian fauna.DiscussionThe integrative evidence indicates that only H. coarctata and H. tenuidentata are currently valid Hierodula species in Iran, with H. macrostigmata as a junior synonym of H. coarctata and previous Iranian reports of S. trimacula rejected. The clear molecular separation between H. coarctata and the H. tenuidentata complex, combined with broad morphological variability in traits such as forefemoral spine coloration, underscores the need to abandon historically overemphasized colour characters and highlights the utility of COI barcoding in resolving conservative mantid lineages. Remaining uncertainty regarding the status of H. transcaucasica versus H. tenuidentata at a broader Eurasian scale calls for a forthcoming multi-locus, range-wide revision to formally resolve their taxonomy.

Black soldier flies (BSF), Hermetia illucens , are industrially important species. They can consume large amounts of spoilt organic material as larvae and bio-convert it to more useful biomass. Female BSF lay eggs in crevices adjacent to spoilt organic materials that serve as an oviposition attractant. In an industrial setting, the efficient oviposition attractants are crucial for centralised egg deposition and maximization of the number of larvae that can be used for biomass conversion. However, the composition and origin of oviposition cues remain undefined, and no synthetic oviposition attractants are currently available. This work aimed to identify key components of naturally occurring oviposition attractants and to formulate an effective synthetic alternative for BSF. We have developed a novel oviposition assay and found larval food- and frass-based attractants to be the most effective at centralizing egg laying. We have identified the volatile compounds in the headspaces of putative attractants and established that the antennae of the female flies respond to some of these compounds. Behavioural validation using synthetic compounds allowed us to generate a mixture of 5 compounds (p-cresol, decanal, sulcatone, pentanoic acid, acetophenone) that cues oviposition as efficiently as currently used natural oviposition attractants. We also identified a synthetic mixture that deters oviposition in BSF. The synthetic attractant and repellent we generated are likely to simplify BSF rearing in research and industrial settings.

During the evolution of insects, two principal types of attachment systems, hairy and smooth, evolved that enable them to attach to and move across diverse surfaces. Both rely on attachment supported by a thin film of fluid that enhances functionality. In some insects, multiple pad types occur on the same leg, each fulfilling complementary roles during attachment. Although their structural and mechanical differences are well understood, the secretion’s chemical composition and its functional implications remain largely unexplored. Stick and leaf insects (Phasmatodea) provide an ideal model to investigate these aspects, as they possess two morphologically and functionally distinct smooth attachment pads on the same tarsus: the pretarsal arolium, responsible for adhesion, and the tarsal euplantulae, specialised for friction. Using polydimethylsiloxane-coated solid-phase microextraction fibres and gas chromatography–mass spectrometry, we analysed the hydrocarbon profiles of both pad types and the body surface of Medauroidea extradentata. These data were compared with published profiles from other insect taxa possessing either hairy or smooth attachment systems to place our findings in a broader phylogenetic and functional context. Our analyses revealed distinct hydrocarbon compositions consistent with the specific mechanical roles of each structure. The arolium secretion was enriched with long-chain, methyl-branched hydrocarbons, likely enhancing fluidity and capillary forces, whereas the euplantulae secretion contained shorter, less methyl-branched hydrocarbons, suggesting higher viscosity, improving frictional contact. The body surface contained only n-alkanes, likely forming a wax-like protective layer. Comparisons across taxa revealed significant differences between smooth and hairy systems, reflecting both functional and phylogenetic influences on fluid chemistry.

The conversion of natural habitats into agricultural and urban areas has led to habitat loss and respective fragmentation as well as decline in habitat quality within the remaining natural habitat patches. Today, this negative trend is particularly pronounced in tropical forest ecosystems. For instance, the formerly continuous East African coastal forest has shrunk over time to relatively few, mostly small forest patches of varying size, isolation, and habitat quality. In this study, we analyse butterfly responses to environmental change and habitat disturbance across selected coastal forest patches in southern Kenya, including protected forest and sacred Kaya forests. We surveyed butterflies in nine forest remnants along the Kenyan coast from the years 2022 to 2025 based on transect counts and bait traps. We recorded a total of 4,893 butterflies representing 187 species. Species richness differed significantly among forests. Butterfly diversity, but not abundance, was highest in the largest forest area, i.e. the Arabuko Sokoke forest (107 species), while seven small Kaya fragments exhibited reduced species numbers (max. 70 species), with lowest number in Kaya Kambe and Shimba Hills. However, total Kaya richness was considerably higher (167 species) than that of the much larger and largely intact Arabuko Sokoke and Shimba Hills forests combined (111 species). Species turnover was high, with 12.4

Avoiding desiccation is paramount for all terrestrial insects, especially in climatically challenging mountainous environments characterised by rapid changes in temperature. A key component in the insects' repertoire to avoid water loss is a thin waxy layer on the insects' cuticle - the cuticular hydrocarbons (CHCs). These can be modified to reduce cuticular transpiration, but they are also restricted by their communication function and by physiological properties like age. Here, we use montane bumblebees to assess the relative importance of abiotic features (temperature) and internal factors (relatedness and age) in 'shaping' the cuticular hydrocarbon profiles. We perform inter- and intraspecific comparisons of twelve species collected along a 1560 m elevational climate gradient (from 800 to 2400 m a.s.l.). Intraspecific analyses revealed that the cuticular hydrocarbon profiles are associated with bumblebee worker age. Interspecific comparisons showed that cuticular hydrocarbon profiles are species-specific corroborating the genetic element. Our results suggest that the cuticular hydrocarbon profile responses to abiotic factors - like temperature and humidity - are constrained by physiological features. This highlights the intricacy of different features shaping the CHC profiles and raises issues about the acclimatisation capability of these important pollinators to climate changes. We suggest that future investigations of cuticular hydrocarbon profiles should incorporate physiological features that are related to fitness, such as the insects' nutrition, body size and fat content.

The European Biodiversity Strategy for 2030 aims at safeguarding areas that harbour high biodiversity. While such protected areas (PAs) are mainly designated with respect to plants and vertebrates, their ability to conserve invertebrates, in particular insects, is still debated. A central question is, whether PAs can sustain the functionality of insect assemblages, that is to preserve a rich space of functional traits. Here, we use a long-term database (1960–2022) on macro-Lepidoptera from northern Austria in combination with a newly compiled large dataset on species traits to compare temporal trends in the distributions of functional traits of butterflies and macro-moths inside and outside selected larger protected areas. We contrast temporal trajectories in the distributions of species body size, numbers of host plants, and dispersal ability. Mean species body weight significantly increased over time inside PAs, while host plant diversity and mobility increased outside PAs. Particularly monophagous species disappeared outside PAs. Total trait spaces did not significantly change over time. Overall, PAs appeared to be more conservative with respect to trait distributions than the surrounding areas and were able to retain the level of functioning as before designation.