Abstract The evolutionary constraints on host plant preferences of herbivorous insects are a question of theoretical and practical importance. Since larvae have limited mobility, natural selection pressures should promote host plant choices by adults that optimise larval survival. Such optimal host utilisation is predicted to reinforce the evolution of specialisation. This concept is expressed and tested as the ‘preference‐performance hypothesis’ (PPH), which predicts a positive relationship between adult preference and larval performance. Through a series of choice and no‐choice experiments, the preference‐performance relationship was examined for the oligophagous tortoise beetle, Cassida rubiginosa , used for biocontrol of thistle weeds. It was hypothesised that adult host plant choices based on olfaction, final location, feeding intensity and oviposition are adaptive and reflect the optimal hosts for larval performance (survival). In accordance with the PPH, there was a positive relationship between all measures of adult preference and larval performance. Adult preference based on olfactometer experiments showed a significant but weak correlation, explaining 27.6% of the variation in larval survival. The strongest correlation was found for adult preference measured as the amount of feeding, explaining 72.5% of the variation in larval survival. Adult preference based on location at the end of the experiment showed a similarly strong correlation, explaining 69.4% of the variation in larval survival. Adult preference based on oviposition and the number of hatched larvae was moderately correlated with larval survival, explaining 46.8% and 48.7% of larval survival, respectively. While there is a significant positive relationship between preference and performance, adult host preference is only a moderate predictor of larval performance. The adult beetle showed substantial flexibility in host plant selection, and equal performance across most Cardueae hosts. This is likely due to the larvae being more sensitive to physical and chemical defences, and possibly an evolutionary lag in the host range between the life stages. Any expansion of the realised host range will be limited by the ability of the larva to adapt to suboptimal hosts.
Abstract Dispersal is a key ecological process influencing population persistence, range expansion and species responses to environmental change. Temperature has a direct impact on insect dispersal through its effects on physiology and behaviour, and prior exposure to various thermal regimes can further alter performance through phenotypic plasticity. We investigated how thermal acclimation, ambient temperature and habitat characteristics influence field dispersal of the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), using mark–release–recapture experiments conducted across seasons in orchards with and without host plants. Ambient temperature was a strong predictor of recapture success in both sexes, with capture rates increasing significantly as field temperatures increased. Female recaptures were 2.6 times higher in orchards containing host plants, whereas male recaptures were unaffected by host presence. Males exhibited a significant decline in recapture rates with increasing distance from the release point, while female captures were more strongly associated with host availability than with distance. In contrast, thermal acclimation at 20°C, 25°C or 30°C had no detectable effect on recapture rates or dispersal patterns. Our findings indicate that immediate environmental conditions and resource availability exert a stronger influence on medfly dispersal than recent thermal history. More broadly, these results suggest that short‐term behavioural responses to local environmental conditions may be more important than acclimation effects in determining movement patterns of highly invasive insect species, with implications for predicting pest spread and improving monitoring and management strategies under changing climates.
Abstract Rescue behavior is observed across the animal kingdom. For example, many ant species engage in rescue activities. This study used experimental approaches to understand how rescuers prioritized rescue targets in the fire ant Solenopsis invicta . This research also investigated the cues that S. invicta used to locate rescue targets. We found that rescue teams likely used chemical signals to locate larval rescue targets. Reproductive larvae were preferentially rescued over worker larvae in simple choice trials; however, caches of multiple worker larvae were given equal priority during rescue compared to single reproductive larvae. Non‐nestmate reproductive larvae were rescued at the same frequency as nestmate reproductive larvae. Our results provide information on how ants locate distressed conspecifics, supporting the use of chemical signalling. Our study also offers insight into rescue priority, belying expectations of kin and reproductive prioritization by demonstrating that mass can override caste preferences. Overall, this study provides evidence that olfactory cues contribute to the coordination of rescue behaviour and suggests that large groups of workers may actually hold equal value to a eusocial insect colony as a single reproductive.
Abstract Insects commonly live in environments rich in opportunistically pathogenic microbes and thus have evolved traits that decrease the likelihood of infection and subsequent loss of fitness. In many cases, these adaptations involve other microbes, which aid in preventing pathogen colonization via the production of antimicrobial compounds, pathogen blocking or immune priming, thus modulating the reactivity of the host immune system once challenged. Here, we use the gazelle dung beetle Digitonthophagus gazella to assess the role of the host's complex microbiome in supporting host immune functions, including basal protein concentration, phenoloxidase activity and lysozyme‐like activity in the larval hemolymph and the host's ability to overcome an experimentally induced and standardized immune challenge. We find that the inherited microbiome mediates an increase in larval mass and basal hemolymph protein concentration throughout development yet does not affect basal hemolymph phenoloxidase or lysozyme‐like activity. Further, the presence/absence of a microbiome did not affect the host's ability to survive experimentally induced exposure to Serratia marcescens . These results are discussed in light of both dung beetle ecology and insect‐microbiome interactions broadly. Taken together, results suggest that the D. gazella microbiome may function primarily to enhance development rather than immunity.
Abstract Plants are often attacked by multiple insect herbivores throughout their lifetime. Early‐arriving herbivores play a critical role in shaping plant responses, which in turn affect subsequent interactions. Later‐arriving herbivores can exploit damaged plants, but their role in modifying interactions and plant performance remains unclear. Thus, it is important to examine host plant preferences in late‐arriving herbivores, the cues guiding their behaviour, and the consequences of multiple herbivores. We examined interactions between two insect herbivore specialists, Acalymma vittatum (Coleoptera: Chrysomelidae) and Anasa tristis (Hemiptera: Coreidae), which often overlap in sequence on shared Cucurbitaceae host plants. We characterized natural succession patterns, identified the cues influencing early‐ and late‐arriving herbivores, and tested the preference–performance hypothesis by determining whether the field‐identified cues driving A. tristis attraction and oviposition predicted improved offspring performance on plants previously colonized by A. vittatum . Finally, we investigated how A. vittatum ‐mediated recruitment of A. tristis influenced plant growth and reproductive traits by manipulating herbivory from both species in field experiments. Field patterns showed that the presence, abundance, and oviposition behaviour of the late‐arriving herbivore, A. tristis , were strongly influenced by the presence and feeding activity of the early‐arriving herbivore, A. vittatum , but only on plants in the genus Cucurbita . In both choice and no‐choice bioassays, A. tristis adult females preferentially selected seedlings with active A. vittatum herbivory, and first‐instar hatchlings exhibited 28% greater growth on seedlings previously damaged by A. vittatum . A. tristis adult females did not respond to A. vittatum aggregation pheromone (chemical cue indicative of herbivory) in short‐range choice tests, nor to non‐ Cucurbita seedlings, regardless of prior herbivory. Field experiments showed that successive herbivory by A. vittatum and A. tristis significantly altered plant reproductive traits, delaying anthesis and reducing male flower and fruit production compared to control plants and those exposed only to A. vittatum . However, crop variety influenced the magnitude of these effects. Together, these findings demonstrate that early‐arriving herbivores induce plant responses that increase the abundance of subsequent herbivores, with cascading negative effects on plants, compounding the effects of these herbivores.
Abstract Plant responses to insect feeding mediate interactions with other community members and may influence community assembly on the induced plant. Since plants perceive herbivory through damage patterns and salivary components, changes in these herbivore traits, such as caused by parasitism, may alter herbivore‐induced plant‐mediated interactions. Upon parasitism, many parasitoids inject a combination of polydnavirus and venom into their host. In doing so, the host's behaviour and physiology are modified. The injection of polydnavirus has been identified as a prominent driver of plant‐mediated interactions initiated by parasitised herbivores. However, most evidence for such plant‐mediated effects comes from greenhouse or laboratory studies. We investigated the ecological consequences of parasitism and its associated injection components on assembly of arthropod communities in an open‐field setting. We exposed wild Brassica oleracea plants to herbivory by unparasitised Pieris brassicae caterpillars, caterpillars parasitised by Cotesia glomerata , caterpillars injected with polydnavirus and/or venom, and we used uninduced plants as control. We monitored the naturally occurring arthropod community on these plants throughout the growing season, focusing on both overall community composition and the abundance of individual species. Arthropod community composition was marginally affected by components of parasitism and subtle effects were found for interactions with specific herbivore species. Plants damaged by P. brassicae injected with both polydnavirus and venom were colonised more often by Mamestra brassicae caterpillars, Myzus persicae aphids and aphid parasitoids compared to uninduced plants or plants induced by unparasitised P. brassicae caterpillars. Our results show that parasitoid polydnavirus and venom, either alone or in combination, affect colonisation by members of the arthropod community in a natural field setting. These modulating effects deserve attention in future studies that investigate the dynamics of plant‐arthropod communities.
Abstract Motivational trade‐offs between reproduction and survival in two sexes of praying mantids may influence the occurrence of sexual cannibalism, a behaviour in which one mate consumes the other before, during or immediately after mating. By using virgin mantids, we tested whether sexual cannibalism emerges opportunistically from contrasting priorities between the sexes: females prioritising foraging over mating and males prioritising mating over risk avoidance. Through behavioural assays, we found that female mantids preferred attacking prey rather than conspecific males and unlikely treated males as typical prey. Meanwhile, males exposed to sex pheromones showed reduced predation on prey. They also exhibited lower vigilance in the presence of either visual or chemical cues of mating opportunities, even under potential predation risk. These findings suggest that sexual cannibalism in virgin animals might reflect opportunistic behavioural decisions affected by conflicting cues within each sex.
River damming profoundly modifies natural riparian zones, yet the successional trajectories of biological communities in the novel riparian ecosystems created by dam operation remain poorly understood. From 2015 to 2024, we conducted six field surveys of arthropod communities along elevational gradients in the riparian zone of the Three Gorges Reservoir. We examined temporal dynamics in biodiversity, spatial distribution patterns and the mechanisms governing community assembly under the influence of reservoir operations. In response to flooding stress, the riparian arthropod community developed a distinct spatial zonation along the elevational gradient, characterized by a unimodal pattern with abundance and taxonomic richness peaking at 170 m. The relative abundance of predators and herbivores decreased with elevation, whereas that of detritivores and omnivores increased. Interannual dynamics revealed that both the composition and structure of riparian arthropod communities stabilized after 2018, with no significant differences observed among subsequent years. This trajectory was further supported by beta-diversity across elevations, which remained stable after 2021. Community stabilization is driven by a two-stage assembly mechanism. Initial inundation stress acted as a stringent environmental filter, eliminating submergence-intolerant species and restructuring community composition. Subsequently, dispersal processes, rather than niche differentiation, became the dominant force maintaining community dynamics. This was evidenced by a significantly negative values of the Dispersal-Niche Continuum Index, reflecting directed migration and rapid recolonization along the elevational gradient. Our study demonstrates the importance of migration and colonization processes in shaping successional trajectories of riparian arthropod communities in regulated rivers. This process relies fundamentally on connectivity with adjacent terrestrial areas, which serve as critical refugia and source populations during inundation. Conserving riparian biodiversity in dam-regulated rivers therefore requires extending management to these adjacent terrestrial habitats.
Abstract Wolbachia , a maternally transmitted Gram‐negative bacterium, infects a significant proportion of arthropods, with Lepidoptera exhibiting some of the highest infection rates. This review synthesised current knowledge on the evolutionary ecology of Wolbachia in Lepidoptera, with a focus on functional effects, transmission patterns and practical applications. Wolbachia drives mitochondrial haplotype homogenisation and mito‐nuclear discordance, complicating phylogenetic studies. While Wolbachia threatens endangered species by reducing genetic diversity and effective population size, it also offers biocontrol potential against agricultural pests. Horizontal transmission, facilitated by hybridisation, parasitoids, predation and environmental mediation, enables cross‐species spread, with strains from supergroups A and B prevalent in Lepidoptera. Phylogenetic analyses reveal non‐concordance between Wolbachia and host or geographic lineages, likely due to host migratory behaviour. Future research should prioritise multi‐omics approaches, field monitoring tools and risk assessment models to harness Wolbachia for biodiversity conservation and sustainable pest management.
Although arthropods are key agents of detritus decomposition, the extent to which environmental heterogeneity modulates this process through shifts in community composition remains poorly understood, particularly in high-elevation ecosystems. We examined animal-derived detritus (yak carrion) decomposition on the Qinghai-Tibet Plateau, partitioning direct spatial (grassland, shrubland, riverbank and wetland) and temporal effects (July-September) from those mediated by arthropod assemblages. Our results reveal that species richness and abundance varied significantly among habitats and sampling months, with species richness highest in grasslands, particularly in July, whereas abundance peaked in shrublands, especially in September. Multivariate analyses revealed pronounced habitat-level differentiation in arthropod community composition and strong associations with environmental variables, especially vegetation richness. Decomposition rates (K) were substantially higher in grassland and shrubland than in riverbank and wetland habitats, peaking in July for grasslands and in September for shrublands. Structural equation modelling (SEM) revealed that decomposition was directly driven by habitat type rather than indirectly through arthropod richness and abundance, demonstrating that environmental heterogeneity on the Qinghai-Tibet Plateau dominates over biodiversity effects on ecosystem functioning and highlighting the context-dependent nature of arthropod-mediated decomposition.
Livestock agriculture is a primary driver of anthropogenic greenhouse gas (GHG) emissions, with cattle dung acting as a significant source of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Dung beetles (Coleoptera: Scarabaeidae) are critical ecosystem service providers that modify dung structure, yet their influence on specific GHG fluxes remains variable across different climatic regions and beetle assemblages. In Australia, where introduced beetle species are active year-round, their potential for GHG mitigation is poorly quantified. We investigated the impact of dung beetle activity on GHG (total, CO2, N2O and CH4) and ammonia (NH3) fluxes from cattle dung. Using 90-day chamber mesocosms, we compared emission profiles between pats colonised by a field-representative mix of four species (Euoniticellus intermedius, E. africanus, E. fulvus and Onthophagus granulatus) and beetle-free controls. Cumulative CH4 flux was 85% lower in beetle treatments compared to controls. Control pats exhibited distinct CH4 flux peaks at Day 6 and Day 16, whereas beetle-colonised pats maintained near-zero fluxes throughout the experiment. Conversely, beetles accelerated initial CO2 release, causing an earlier flux peak within the first 14 days compared to controls. Total greenhouse gas flux was nearly 18% lower when beetles were present. These findings indicate that dung beetle activity is associated with altered greenhouse gas flux patterns in cattle dung. The presence of active beetle populations suggests an inherent ecosystem service that may reduce the net methane footprint of grazing systems. Our study highlights the importance of considering invertebrate-mediated processes in agricultural greenhouse gas assessments. La ganader & iacute;a es uno de los principales motores de las emisiones antropog & eacute;nicas de gases de efecto invernadero (GEI), y el esti & eacute;rcol de vacuno act & uacute;a como una fuente significativa de di & oacute;xido de carbono (CO2), metano (CH4) y & oacute;xido nitroso (N2O). Los escarabajos peloteros (Coleoptera: Scarabaeidae) son proveedores cr & iacute;ticos de servicios ecosist & eacute;micos que modifican la estructura del esti & eacute;rcol; sin embargo, su influencia en los flujos espec & iacute;ficos de GEI sigue siendo variable en diferentes regiones clim & aacute;ticas y comunidades de escarabajos. En Australia, donde las especies de escarabajos introducidas est & aacute;n activas durante todo el a & ntilde;o, su potencial para la mitigaci & oacute;n de los GEI est & aacute; poco cuantificado. Investigamos el impacto de la actividad de los escarabajos peloteros en los flujos de GEI (totales, CO2, N2O y CH4) y de amon & iacute;aco (NH3) procedentes del esti & eacute;rcol de vacuno. Utilizando mesocosmos de c & aacute;mara de 90 d & iacute;as, comparamos los perfiles de emisi & oacute;n entre b & ntilde;igas colonizadas por una mezcla representativa de campo de cuatro especies (Euoniticellus intermedius, E. africanus, E. fulvus y Onthophagus granulatus) y controles libres de escarabajos. El flujo acumulado de CH4 fue un 85% menor en los tratamientos con escarabajos en comparaci & oacute;n con los controles. Las bo & ntilde;igas de control exhibieron picos distintos de flujo de CH4 en el D & iacute;a 6 y el D & iacute;a 16, mientras que las bo & ntilde;igas colonizadas por escarabajos mantuvieron flujos cercanos a cero durante todo el experimento. Por el contrario, los escarabajos aceleraron la liberaci & oacute;n inicial de CO2, provocando un pico de flujo m & aacute;s temprano dentro de los primeros 14 d & iacute;as en comparaci & oacute;n con los controles. El flujo total de gases de efecto invernadero fue casi un 18% menor cuando los escarabajos estaban presentes. Estos hallazgos indican que la actividad de los escarabajos peloteros est & aacute; asociada con patrones alterados de flujo de gases de efecto invernadero en el esti & eacute;rcol de vacuno. La presencia de poblaciones activas de escarabajos sugiere un servicio ecosist & eacute;mico inherente que puede reducir la huella neta de metano de los sistemas de pastoreo. Nuestro estudio destaca la importancia de considerar los procesos mediados por invertebrados en las evaluaciones de gases de efecto invernadero agr & iacute;colas. A pecu & aacute;ria & eacute; um dos principais motores das emiss & otilde;es antropog & ecirc;nicas de gases de efeito estufa (GEE), e o esterco de bovino atua como uma fonte significativa de di & oacute;xido de carbono (CO2), metano (CH4) e & oacute;xido nitroso (N2O). Os escaravelhos do esterco (Coleoptera: Scarabaeidae) s & atilde;o provedores cr & iacute;ticos de servi & ccedil;os ecossist & ecirc;micos que modificam a estrutura do esterco; no entanto, sua influ & ecirc;ncia nos fluxos espec & iacute;ficos de GEE continua sendo vari & aacute;vel em diferentes regi & otilde;es clim & aacute;ticas e comunidades de escaravelhos. Na Austr & aacute;lia, onde as esp & eacute;cies de escaravelhos introduzidas est & atilde;o ativas durante todo o ano, seu potencial para a mitiga & ccedil;& atilde;o dos GEE & eacute; pouco quantificado. Investigamos o impacto da atividade dos escaravelhos do esterco nos fluxos de GEE (totais, CO2, N2O e CH4) e de am & ocirc;nia (NH3) procedentes do esterco de bovino. Utilizando mesocosmos de c & acirc;mara de 90 dias, comparamos os perfis de emiss & atilde;o entre placas de esterco colonizadas por uma mistura representativa de campo de quatro esp & eacute;cies (Euoniticellus intermedius, E. africanus, E. fulvus e Onthophagus granulatus) e controles livres de escaravelhos. O fluxo acumulado de CH4 foi 85% menor nos tratamentos com escaravelhos em compara & ccedil;& atilde;o com os controles. As placas de esterco de controle exibiram picos distintos de fluxo de CH4 no Dia 6 e no Dia 16, enquanto as placas colonizadas por escaravelhos mantiveram fluxos pr & oacute;ximos a zero durante todo o experimento. Pelo contr & aacute;rio, os escaravelhos aceleraram a libera & ccedil;& atilde;o inicial de CO2, provocando um pico de fluxo mais precoce dentro dos primeiros 14 dias em compara & ccedil;& atilde;o com os controles. O fluxo total de gases de efeito estufa foi quase 18% menor quando os escaravelhos estavam presentes. Esses achados indicam que a atividade dos escaravelhos do esterco est & aacute; associada a padr & otilde;es alterados de fluxo de gases de efeito estufa no esterco de bovino. A presen & ccedil;a de popula & ccedil;& otilde;es ativas de escaravelhos sugere um servi & ccedil;o ecossist & ecirc;mico inerente que pode reduzir a pegada l & iacute;quida de metano dos sistemas de pastoreio. Nosso estudo destaca a import & acirc;ncia de considerar os processos mediados por invertebrados nas avalia & ccedil;& otilde;es de gases de efeito estufa agr & iacute;colas.
1. Lepidoptera are highly sensitive to changes in their surroundings, making them excellent indicators of ecosystem health and reflecting driving factors such as climate and land-use change. However, surveying adult butterflies of certain species presents challenges, including their short flight periods, preference for inaccessible positions, including tree canopies, and dependence on favourable and consistent weather conditions. Other life history stages are generally even more difficult to study. 2. Researchers have therefore sought to develop different techniques for monitoring species, with nocturnal surveying of larvae and pupae using ultraviolet light (UV) gaining popularity as a simple, inexpensive, and non-invasive method. 3. To support the increasing adoption of this surveying technique, we have developed guidelines for conducting nocturnal surveys with UV flashlights focusing on: (1) A scale for assessing the suitability of species for nocturnal UV monitoring which has been validated with photoluminescence emission spectroscopy, (2) Detailed scoring against this scale for over 100 species enabling researchers to use the methodology in the field, and (3) Equipment, including selection of UV flashlight type and 4) Specific recommendations for data collection and reporting. 4. It is expected that the adoption of this methodology will provide a consistent approach for collecting and reporting data from different sources, thereby facilitating the comparison of results worldwide.
Abstract Changes in forest management and climate affect forest ecosystems, leading to changes in their structural characteristics. This subsequently affects the structure of forest beetle assemblages (Coleoptera). The underlying mechanisms of structural changes in an assemblage can be disentangled by investigating assemblage composition, diversity, species abundance distribution and body size distributions. However, information on how beetle assemblage structure and body size distributions are affected by combined effects of forest management and tree dieback is lacking. We assessed structural characteristics in 50 forest plots in Darmstadt, Germany, where forest management and tree dieback affected canopy openness, deadwood volume, the proportion of non‐native trees, mean tree size, tree basal area and tree diversity. We analysed beetle assemblage structure in response to changes in forest characteristics using composition, abundance, diversity and three parameters describing species abundance distributions: rate of decline, the proportion of the most abundant species and species richness. Body size distributions calculated based on species presence/absence and all beetle individuals (both literature‐based species mean body sizes) were examined separately to detect shifts in assemblage body size structure. Beetle assemblage composition was affected by all forest characteristics except for tree diversity. In forests with a higher canopy openness, we found less even abundance distributions with fewer but more dominant beetle species. Forest characterised by a lower mean tree size and a higher proportion of non‐native trees showed a higher frequency of smaller‐sized beetles. Different forest beetle assemblages require different structural characteristics. The dominance of individual beetle species and lower diversity in forests with a more open canopy could be attributed to lower resource diversity and the avoidance of such habitats by some species. Furthermore, forests with a high mean tree size and low proportion of non‐native trees favour larger beetle species by providing a higher diversity and larger amounts of essential resources. Overall, the observed responses elucidate the mechanisms underlying changes in beetle assemblage structure in response to forest management and tree dieback.
Abstract Seasonal environmental fluctuations profoundly shape the life‐history strategies of arthropod predators, frequently altering population dynamics and trophic interactions within natural systems. However, how extreme seasonal constraints, such as compounded thermal stress and nutritional bottlenecks, are transgenerationally transmitted via maternal effects remains a critical question in evolutionary ecology. We investigated these transgenerational constraints in the sheet‐web spider Hylyphantes graminicola . We collected field‐matured parental cohorts during early summer (temperate conditions with abundant aquatic insect pulses) and early autumn (severe thermal stress and aquatic resource depletion), and evaluated the developmental and reproductive performance of their F1 offspring under standardized laboratory conditions. The synergistic pressures of late‐summer heat and resource depletion significantly miniaturized early‐autumn maternal phenotypes. This environmentally induced constraint inflicted a deleterious ‘Silver Spoon’ effect on the F1 generation: despite receiving ad libitum prey, the early‐autumn F1 lineage suffered prolonged development, elevated juvenile mortality and a catastrophic collapse in egg hatching rates. Notably, mating behaviors of surviving F1 adults remained robust, indicating a profound decoupling between behavioral canalization and underlying physiological viability. Our results demonstrate a progressive manifestation of nutritional deficits, indicating that generic caloric intake cannot rescue specific maternally inherited biochemical shortfalls. Ultimately, this study illustrates that standard behavioral metrics can mask severe transgenerational physiological distress, emphasizing the evolutionary and demographic vulnerabilities of arthropod populations facing seasonal bottlenecks.
Across complex landscapes, genetic structure can arise through a combination of geographic, ecological and historical processes. In mountain systems, isolation by distance (IBD), environment (IBE) and resistance (IBR) represent three such mechanisms but are often difficult to distinguish. The Great Dividing Range (GDR) of eastern Australia provides an ideal system for evaluating their relative contributions because of its varying elevation and climatic gradients. Here, we investigate the drivers of genetic structure in the Swamp Tigertail (Synthemis eustalacta) using an integrative framework combining population genomics, demographic analysis, morphology and ecological data. Results showed overall low genetic differentiation and no evidence for discrete population structure. Linear mixed-effects model provided no support for IBD but instead showed IBE and IBR, in which any observed genetic differentiation was correlated with environmental gradients, particularly precipitation and temperature extremes, vegetative cover and landscape resistance. Morphological analyses revealed minimal variation among sampled sites, but several traits were sexually dimorphic, suggesting potential sex-biased dispersal. Demographic reconstructions reveal long-term population stability, with paleoniche models displaying shifts in suitable habitat during past climatic oscillations. Together, these results highlight ecological and topographic isolation as key mechanisms shaping genetic variation in S. eustalacta and that montane dragonfly populations may maintain gene flow through climate cycles by tracking suitable conditions across elevational gradients rather than persisting in long-isolated refugia.
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.
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.
The dark diversity of a locality is represented by species from the regional pool that are absent from this locality, even though ecological conditions of this locality are suitable. We tested for latitudinal and altitudinal gradients in the dark diversity and community completeness of flea assemblages parasitic on rodents in three regions of South America at two scales, namely (a) within a locality across all host species (= compound community) and (b) within a locality within a host species (= component community). We found that the dark diversity of compound flea communities increased from north to south and from lower to higher altitudes, but no effect of the interaction between latitude and altitude was detected. The completeness of compound communities decreased from north to south but was not affected by altitude. Similar relationships between dark diversity and latitude were found for component flea communities, but no significant effect of altitude was detected. The relationship between the completeness of component communities and latitude was similar to that of compound communities. We explained the positive relationship between latitude and flea dark diversity by the fact that the latitudinal pattern of flea species richness in South America is opposite to the classical latitudinal gradient of species richness. The occurrence of the altitudinal effect on dark diversity in compound communities and the lack of this effect in component communities suggest that the factors driving the dark diversity of flea communities depend on the scale of consideration.
Understanding how ecologically similar species coexist remains a central challenge in ecology, particularly in polyphagous assemblages where dietary overlap limits differentiation along a single niche axis. Although coexistence theory emphasizes multidimensional niche partitioning, empirical studies integrating spatial, temporal and dietary dimensions remain scarce. In this study, multidimensional niche partitioning was examined in a community of phytophagous scarab beetles across agricultural fields, forests and grasslands in northeastern China. Habitat-level surveys, fine-scale temporal monitoring, olfactory preference assays and DNA metabarcoding of larval gut contents were combined to quantify niche differentiation across spatial, temporal and dietary dimensions. Species exhibited strong habitat segregation at landscape scale, consistent with habitat filtering as a primary structuring process. Within agricultural habitats where multiple species co-occurred, temporal differentiation reduced but did not eliminate overlap. Gut content composition differed significantly among species, although mean dietary overlap did not differ from null expectation. Patterns of olfactory preference closely corresponded to realized diet composition: species with strong olfactory preferences maintained narrower realized diets, whereas species without strong olfactory preferences exhibited broader and more variable resource use. These results suggest that fine-scale differences in resource use may contribute to niche differentiation among sympatric phytophagous beetles, even when overall dietary overlap remains high. By linking olfactory preference to realized dietary composition, this study highlights how behavioural traits can help explain subtle but consistent differentiation in host use among co-occurring belowground herbivores.
Oviposition site selection is a crucial behavioural decision that influences offspring survival. In the giant water bug Kirkaldyia deyrolli, females lay eggs on emergent substrates and males subsequently guard and water the egg masses. Although paternal care provides protection against infanticidal females and terrestrial predators, the extent to which water bug females adjust oviposition behaviour in response to environmental risks remains unclear. We combined field observations, laboratory choice experiments and semi-outdoor manipulations to affect oviposition site selection in K. deyrolli. Females avoided bright, sun-exposed surfaces and substrates connected to the shoreline, instead preferring shaded sites that reduced exposure to direct sunlight. Experimental egg masses placed in full sun exhibited significantly lower hatchability than those in shaded conditions, demonstrating strong desiccation sensitivity. Our findings indicate that oviposition site selection in K. deyrolli is shaped primarily by desiccation risk, highlighting how environmental constraints interact with paternal care to shape reproductive strategies in aquatic insects.
