Abstract Hosts and microbes interact in dynamic relationships that can alter the volatile profile emitted by the microbial community. The extent to which closely related species diverge in these relationships is not well known. Burying beetles associate with a rich microbial community that is present on their breeding resource, a small vertebrate carcass. Prior work demonstrated that Nicrophorus orbicollis manages the microbial community during parental care to alter the volatile profile emanating from the nest, reducing cues for competitors that would usurp the resource. The present study extended this work to N. marginatus to first determine the distinctive volatile cues that attract this species to carrion and then to examine whether parents altered the volatile profile as a competitive adaptation. In two field tests, Nicrophorus marginatus was highly attracted to mouse carcasses supplemented with the chemical dimethyl disulphide compared with control carcasses or carcasses supplemented with methyl thiocyanate or dimethyl trisulphide. There was no synergistic effect on attraction when combining dimethyl disulphide and dimethyl trisulphide. Headspace collection followed by gas chromatography–mass spectrometry analyses revealed that parents that prepared a carcass reduced the emission of dimethyl disulphide by 70.6%. Methyl thioacetate and methyl thiocyanate were also reduced by carcass preparation, while dimethyl trisulphide and dimethyl tetrasulphide were not. The results suggest that the congeners N. marginatus and N. orbicollis interact with their microbial communities in species‐specific ways to enhance competitive ability.

Abstract Global warming is expected to strongly impact insect populations, particularly in montane environments where elevational gradients impose steep climatic variation. Insects in these systems are thought to be especially vulnerable because upward range shifts reduce available habitat. However, few studies have considered the combined influence of temperature and aridity on thermal tolerance at the intraspecific level. Here, we examined physiological and morphological variation in populations of the carabid beetle (Coleoptera) Baripus nevado along an altitudinal gradient (2380, 2644 and 2959 m) in Cerro Nevado, Argentina, an arid mountain system. We measured upper thermal limits (CTmax and upper lethal temperature [ULT]), body size and water loss. Our results revealed significant intraspecific variation: CTmax, ULT, body size and water loss/body size all declined with elevation. Low‐elevation populations exhibited the highest thermal limits and body mass, consistent with adaptations to endure greater aridity and desiccation stress. These patterns contrast with previous studies reporting conserved upper thermal limits within species across elevations, highlighting the role of water availability as an additional selective pressure. Our findings suggest that physiological and morphological diversity within species can buffer climate change impacts, but also indicate that increasing aridity may pose critical challenges even for heat‐tolerant populations. Overall, we demonstrate that intraspecific variation in thermal physiology is shaped by the interaction between temperature and aridity, and that this variation could be key for the persistence of montane insects under climate change.

Abstract Temporal niche partitioning is an important mechanism for minimizing interspecific competition and promoting species coexistence in complex ecosystems. This allows sympatric competing species to exploit resources at different times of the day, minimizing direct competition and providing insights into the evolutionary processes of circadian distribution of communities, resource availability and intra‐ and interspecific competitive pressure. In this study, we examined diel activity patterns (nocturnal and diurnal periods) of dung beetle assemblages (species richness, abundance and assemblage structure) within a conserved region of Amazonian forest using pitfall traps baited with human faeces. Overall, we sampled a total of 430 individuals and 32 species. While dung beetle species richness and abundance did not differ significantly between day and night, a pronounced shift in species composition between diel activity patterns was observed, indicating clear temporal segregation of dung beetle species. Five species were classified as diurnal, four species were considered nocturnal and one species was an activity period generalist. Our findings highlight the importance of temporal dynamics as drivers of dung beetle species distributions in tropical forests, directly influencing resource partitioning and promoting behavioural adaptations that facilitate species coexistence in the Amazon rainforest.

Abstract Ant–plant mutualisms mediated by extrafloral nectaries (EFNs) play a major role in plant defence, yet outcomes of these interactions are highly context‐dependent. Here, I review recent empirical evidence on three interlinked dimensions of these mutualisms, EFN chemistry, ant behaviour and environmental drivers, and examine how their interactions shape whether ant attendance produces net benefits or costs for plants. EFN composition is chemically complex and labile, responding to herbivory, phenology and abiotic stressors (e.g., drought, nutrient limitation), and these chemical traits influence ant recruitment and foraging. Ant species vary in recruitment ability, aggressiveness and dietary breadth, behaviours that predict protective efficacy but also the potential for pollination interference or attraction of exploiters (e.g., honeydew‐associated hemipterans). Environmental factors such as temperature extremes, fire regimes and habitat fragmentation further shape nectar production and ant assemblages, filtering interaction outcomes across space and time. I highlight key trade‐offs (resource allocation to rewards), reproductive costs via pollinator disruption and competition with hemipterans—and identify priority research directions: standardised EFN sampling and chemical/microbial analyses; factorial field experiments manipulating nectar traits and abiotic conditions; behavioural‐based assays across representative ant taxa; long‐term monitoring; explicit studies of microbial modification and EFN–honeydew dynamics; expanded geographic coverage; and development of mechanistic predictive models. Addressing these research priorities will improve our capacity to predict when EFN‐mediated ant attendance benefits plants and to apply that knowledge in conservation and restoration strategies.

Abstract Aquatic emerging insects play a critical role in riparian ecosystems by supporting terrestrial consumers, particularly generalist predators like spiders. Their emergence is highly sensitive to environmental changes such as river regulation and climate change. While previous studies have demonstrated that fluctuations in aquatic insect subsidies influence spider abundance and diversity, little is known about how these changes affect spider morphology and physiology. This study aimed to investigate how flooding affects both aquatic insect emergence and morphological responses of the web‐building spider Tetragnatha extensa (Linnaeus, 1785). We conducted an experiment using a riparian stream mesocosm facility, simulating four flooding events between May and September. Aquatic insects were sampled using emergence traps during all flooding events, while spiders were collected at the beginning and end of the experiment. To assess developmental stress, we measured spider head size and fluctuating asymmetry using landmarking and geometric morphometrics. Spiders in flooded mesocosms exhibited ~15% lower fluctuating asymmetry than those in controls, suggesting reduced developmental stress. This likely reflects the 45% higher emergence of chironomids, the main prey of T. extensa . These results indicate that spider developmental stability is responsive to prey availability and that geometric morphometrics is a sensitive tool for detecting such prey‐mediated ecological effects. Climate change, water use and river regulation, through altered flooding regimes, can disrupt cross‐ecosystem fluxes by affecting the emergence of aquatic insects. Reduced prey availability may, in turn, impact spider physiology and propagate into the riparian ecosystem through altered fitness, reproductive success and population dynamics of terrestrial consumers.

Abstract Endosymbionts usually develop strategies that can enhance their persistence within host populations. Wolbachia , a prevalent endosymbiont, induces phenotypes that promote its spread, often at the cost of host fitness. However, demonstrating these strategies in laboratory settings can be challenging due to confounding factors, such as antibiotic treatment or number of host lines. A previous study on a single antibiotic‐treated Drosophila sturtevanti line paradoxically found lower fecundity in infected females, even though most females in the population were naturally infected and reproductive phenotypes were expected. Here, we investigate the impact of Wolbachia infection on the fecundity across multiple lines of D. sturtevanti , focusing on whether there is a consistent reduction in fecundity. Additionally, we aim to distinguish the phenotypic effects of Wolbachia infection from those of antibiotic treatment. We dissected a total of 1680 ovaries from females at seven maturity stages across six lines of D. sturtevanti : three naturally infected and three uninfected. Also, all lines underwent antibiotic treatment to assess its impact on fecundity. Our results suggest no difference in fecundity between infected and uninfected lines, indicating that Wolbachia infection does not regulate this trait in the host population. However, antibiotic treatment reduced fecundity across all lines, with a more pronounced decline in infected ones. These findings highlight the inconsistency of antibiotic treatment outcomes and the risk of misinterpreting Wolbachia 's fitness effects when relying on a single treated line. The study emphasizes the need for refined methods and more accurate analyses to assess Wolbachia ‐induced phenotypic diversity.

Abstract Environmental stressors can limit access to resources in numerous ways, shaping organism condition and fitness within and across generations. Resource constraints are especially important for sexual selection, as many components of mating behaviour, from sexual signalling to sperm production, are condition‐dependent. Environmental stress can therefore be an important ecological mediator of patterns of sexual selection. The role of condition on mating behaviour and reproductive success may be particularly acute in males, who typically express greater condition dependence than females for many sexual traits. However, most studies in insects and other invertebrates consider classic model species, and haplodiploid species are under‐represented. In this study, we measured condition‐dependent male reproductive success in the haplodiploid spider mite Tetranychus urticae . Males were placed in different host plant environments generating different stress levels (bean = low stress, tomato = intermediate and tomato with cadmium = high stress) during their juvenile stage. The impact of the male juvenile environment was measured by placing males, once adult, with females from a low stress environment. We measured several fitness traits for males, including mating success, partner fecundity, number of female offspring reaching adulthood and offspring sex ratio. Juvenile environment did not influence adult male mating success, but males from the high stress environment suffered reduced reproductive success producing fewer female offspring, suggesting that stressed males either pass fewer sperm or lower quality seminal fluid to females if they do mate. Likewise, offspring sex ratios were correlated with male stress, with sex ratios becoming less female‐biased with increasing juvenile stress. The male juvenile environment in a haplodiploid species can reduce its reproductive success and prevent females mated to these males from producing optimal offspring sex ratios. Environmental stress experienced by adults can therefore impact both males and females and, through effects on sex allocation, their offspring.

Abstract We used life tables to model rates of population growth when egg cannibalism by specific life stages increases developmental rate and/or fecundity, using aphidophagous coccinellids as a model system. Sibling egg cannibalism was beneficial for population growth; a modest (10%) increase in developmental rate or fecundity was sufficient to favour cannibal over non‐cannibal populations, provided the rate of cannibalism remained low. The highest rates of population growth occurred when cannibals received both developmental and fecundity benefits, the former being more beneficial than the latter. As cannibals increased in number, the costs to population growth rate eventually outweighed the individual life history benefits, such that the proportion of cannibal individuals (or cannibalism rate) was limited in a frequency‐dependent manner. Simulations of cannibalism by later stages (fourth instar larvae or adults) often led to cannibals comprising more than 50% of the population, depending on the magnitude of individual benefits, as the costs of cannibalism (mortality) were shared by both cannibals and non‐cannibals, in contrast to sibling egg cannibalism, in which cannibals alone bore the costs. We conclude that cannibalism can evolve in the absence of resource limitation, as cannibals can easily invade non‐cannibal populations when they gain life history benefits, although higher levels of cannibalism become self‐limiting by the constraints they impose on population growth rate.

Abstract Movement is fundamental to population persistence and metapopulation dynamics, but robust comparative estimates of dispersal remain scarce for threatened butterflies. Limited quantitative data on movement constrain effective conservation network design. We focused on three threatened butterfly species— Euphydryas aurinia , Parnassius apollo and Phengaris arion —co‐occurring on Gotland, Sweden, which together provide an ideal model for comparative dispersal analysis. To quantify and compare movement patterns among species using extended capture–mark–recapture (CMR) data, test for random‐walk behaviour, and identify the best‐fitting dispersal kernels. CMR datasets for E. aurinia and P. apollo were extended to 2024 and combined with comprehensive data for P. arion , yielding 9670 net‐displacement observations (the distance between the first and last captures) collected from 2017 to 2024. One movement value per individual was used to avoid pseudoreplication, detection probabilities were estimated with Cormack–Jolly–Seber models, and four dispersal kernels were evaluated. Median net displacement differed significantly among species (χ² = 450.14, p < 0.001): E. aurinia showed the lowest value (0.135 km), while P. apollo (0.253 km) and P. arion (0.252 km) were similar. Movements deviated from random‐walk expectations (log–log slope = 0.431 versus 0.5 expected, p < 0.001), indicating area‐restricted movement. Lognormal kernels best described E. aurinia and P. apollo , whereas an exponential distribution fitted P. arion best, with maximum displacements of 8.19, 10.69 and 4.31 km, respectively. Even butterflies traditionally regarded as sedentary exhibit substantial dispersal capacity. Species‐specific movement strategies influence metapopulation connectivity, and the derived parameters provide essential inputs for designing habitat networks within each species's dispersal range.

Abstract Alpine and subalpine ecosystems are predicted to have increased temperature and altered seasonal rainfall and snow cover duration as climate change progresses, potentially changing the communities of these ecosystems. Soil arthropods facilitate key environmental processes that determine ecosystem function and stability; however, little is known about how warming and drought conditions impact soil arthropod communities in the field. This study aimed to assess the effects of soil warming and drought conditions on the abundance and diversity of soil arthropod communities. Climate‐controlled shelters manipulated soil temperature and incoming precipitation in a factorial experiment (FutureClim) in a subalpine grassy herbfield in Australia. Surface‐active arthropods were sampled from climate‐controlled shelters using pitfall traps in January, March and April 2023 and were identified to order. Abundance, diversity and community composition changed significantly across the sampling period. Diversity was lowest in all warming and drought treatments in April relative to control, while community composition was significantly driven by temperature and moisture but also was highly variable across the site. The effects of warming and drought on abundance differed substantially between arthropod taxa, with opposing effects on mesofauna and macrofauna. Two Collembola orders, which comprised a large proportion of the arthropod community, were more abundant in heated shelters during the cooler months. In contrast, Hymenoptera (mostly driven by the dominant alpine ant Iridomyrmex alpinus ), Hemiptera and Diptera were more abundant in drought and heat‐drought conditions, but larvae were scarce in droughted treatments. Collectively, this study suggests that the abundance, composition and possibly diversity of surface‐active mesofauna and macrofauna will likely change in the future. Focus on phenological shifts of communities over both short and long timescales, coupled with vegetation and soil changes, is needed to better understand potential ecological changes associated with soil warming and drying.