Mark K. L. Wong

Biological invasions threaten biodiversity and ecosystem functions, often causing cascading effects across trophic levels. Yet how these impacts vary over the fundamental day–night cycle remains largely overlooked. On Barrow Island, a high-conservation-value reserve off northwestern Australia, we examined how infestations of the non-native scale insect Saissetia miranda (Hemiptera: Coccidae) on a dominant native tree species – the fig Ficus brachypoda – influenced native arboreal invertebrate communities and ant-mediated ecosystem functions in a natural matched-pairs experiment, comparing scale-infested versus uninfested sites. We observed the ecologically dominant native meat ant Iridomyrmex sanguineus collecting carbohydrate-rich honeydew from the non-native scale insects on fig trees. Although the meat ants are primarily diurnal, their nocturnal foraging activity increased by 164% at infested sites. Scale-infested sites supported higher abundances of arboreal invertebrates (~28% higher overall). In particular, scale infestations boosted the nighttime abundances of moth and cockroach species, which were observed feeding on excess honeydew, as well as spiders, possibly preying on these groups. Moreover, we uncovered knock-on effects on ant-mediated ecosystem functions in the brown and green food webs of infested sites. On the ground, the higher nocturnal ant activity contributed to a 207% increase in the mass of protein baits scavenged by ants during the night. In the canopy, there was a nearly fivefold increase in ant attacks on insect herbivores, as well as a 35% reduction in leaf damage across diel periods. Our findings show that non-native hemipterans can trigger carbohydrate-rich pulses in ecosystems, reshaping ant behaviour and amplifying both ant–herbivore interactions and higher-order effects on multitrophic communities. Critically, these impacts are not uniform across the diel cycle, but disproportionately affect nocturnal assemblages. Recognising the temporal dimension of invasion impacts is crucial for understanding and managing their full ecological consequences.

Biological invasions threaten biodiversity and ecosystem functions, often causing cascading effects across trophic levels. Yet how these impacts vary over the fundamental day–night cycle remains largely overlooked. On Barrow Island, a high-conservation-value reserve off northwestern Australia, we examined how infestations of the non-native scale insect Saissetia miranda (Hemiptera: Coccidae) on a dominant native tree species – the fig Ficus brachypoda – influenced native arboreal invertebrate communities and ant-mediated ecosystem functions in a natural matched-pairs experiment, comparing scale-infested versus uninfested sites. We observed the ecologically dominant native meat ant Iridomyrmex sanguineus collecting carbohydrate-rich honeydew from the non-native scale insects on fig trees. Although the meat ants are primarily diurnal, their nocturnal foraging activity increased by 164% at infested sites. Scale-infested sites supported higher abundances of arboreal invertebrates (~28% higher overall). In particular, scale infestations boosted the nighttime abundances of moth and cockroach species, which were observed feeding on excess honeydew, as well as spiders, possibly preying on these groups. Moreover, we uncovered knock-on effects on ant-mediated ecosystem functions in the brown and green food webs of infested sites. On the ground, the higher nocturnal ant activity contributed to a 207% increase in the mass of protein baits scavenged by ants during the night. In the canopy, there was a nearly fivefold increase in ant attacks on insect herbivores, as well as a 35% reduction in leaf damage across diel periods. Our findings show that non-native hemipterans can trigger carbohydrate-rich pulses in ecosystems, reshaping ant behaviour and amplifying both ant–herbivore interactions and higher-order effects on multitrophic communities. Critically, these impacts are not uniform across the diel cycle, but disproportionately affect nocturnal assemblages. Recognising the temporal dimension of invasion impacts is crucial for understanding and managing their full ecological consequences.

Tree‐related microhabitats (TreMs), such as water‐filled tree holes (WTHs), are important structures for forest biodiversity, providing habitats for many specialized species, which are however impaired by the intensive forest management of the past. Strategies to maintain and promote TreMs in managed forests, e.g. by establishing old‐growth forest patches as stepping stones, have been implemented, but their success has rarely been tested. We experimentally created WTHs in old‐growth patches that were established to connect forest nature reserves (FNRs) in a beech forest in Germany. Eight years after creation, we sampled, identified, and measured traits of the invertebrate community that colonized the WTHs. We then investigated how spatial and environmental variables affected taxonomic and functional attributes of communities and populations. A total of 2407 individuals of 13 species were sampled, the majority of which were insect larvae. Abundance, as well as taxonomic and functional diversity attributes and community composition, were influenced by environmental and spatial factors, generally supporting the patch‐dynamics and species‐sorting metacommunity archetype. At the population level, both spatial and environmental factors affected the abundance and functional diversity of body size distributions, suggesting that dispersal capacities, microhabitat requirements, and competitive abilities of individual species structure communities. The distance to the FNRs had a positive effect on total invertebrate abundance and the abundance of the specialized marsh beetle Prionocyphon serricornis , and a weak negative effect on the functional diversity of the community. Our study underpins the stepping‐stone concept of connecting FNRs. The species colonized all newly created microhabitats from source populations, indicating that these patches increase connectivity between the FNRs and thus contribute to forest biodiversity conservation. The negative effects of distance to FNRs on functional diversity suggest that distances between habitat patches should be kept small for such a strategy to be successful and sustainable in the long term.

The pace of biodiversity loss outstrips our ability to conserve Earth's most diverse group of named species—the insects (Arthropoda: Insecta). We increasingly rely on trait‐based metrics to understand how insects respond to and affect their environment. Traits provide insights that aid conservation assessment and planning. Yet, we lack a centralised trait database for insects, hampering insights that could inform ecological research and conservation management planning. We propose the creation of the Global Repository of Insect Traits (GRIT). GRIT will cover all world regions, realms and insect taxa. It will provide open and FAIR access to comprehensive trait data compiled from both currently available and future datasets. This proposal is an open call for all to join a global network of collaborators in a collective effort to accelerate the compilation of insect trait data and increase the transparency of data sharing and accessibility in the field. We envision the use of state‐of‐the‐art methods in trait acquisition and imputation to build computational tools that can extract and validate trait data from unstructured text, accelerating information availability by orders of magnitude. We anticipate the development of analytical tools that contribute to a governance structure, ensuring the long‐term success of the database and extraction tools. Finally, we outline future opportunities and identify several research questions that could be readily answered once data are assembled. Recognising the numerous challenges inherent in this project, we invite a robust discussion on strategies to effectively address obstacles.

Many broad‐scale studies along spatial and habitat gradients show that organisms' traits can strongly influence community assembly by facilitating dispersal and environmental filtering. Nonetheless, how traits structure local faunal communities within habitats remains poorly understood. In particular, the often‐assumed role of traits in affecting the outcome of competition among animal species is rarely tested. We coupled a field study with a mesocosm experiment to explore how arboreal ant species' traits shaped competition and community structure, leveraging a small mangrove ecosystem which conceivably imposed minimal dispersal and environmental filtering effects on ant community assembly. We first surveyed the ant communities inhabiting 115 mangrove trees using >2000 carbohydrate and protein baits, and measured multiple morphological, physiological (critical thermal maximum) and dietary (stable isotope trophic position) traits of all ant species. We then coupled co‐occurrence network analyses with meta‐analytical models to uncover the trait‐based mechanisms structuring species co‐occurrences in the field. Finally, in a mesocosm experiment, we reared 87 colonies of eight ant species from the mangrove over 30 days under different competition treatments to investigate trait‐mediated effects of competition on ant colony performance. Patterns of ant species co‐occurrences and bait recruitment indicated strong competition for limited protein‐rich resources. Accordingly, dissimilarities in three traits—eye size, pronotum width and antennal scape length—consistently explained species co‐occurrences, suggesting that the communities were competitively assembled by a partitioning of resource acquisition strategies among species. Species co‐occurrences were also, to a lesser extent, explained by similarities in critical thermal limits, suggesting mild environmental filtering. In the mesocosm experiment, increasing directional differences in eye size and pronotum width between neighbouring ant colonies exacerbated interspecific competitive effects on colony survival and growth. Our results empirically demonstrate that traits linked to resource acquisition shape both coexistence and exclusion in ants. More broadly, by contrasting field patterns of niche partitioning with experimentally measured competitive effects, we show that the same traits can underpin stabilising processes that promote coexistence through limiting similarity, or equalising processes that drive exclusion through hierarchical differences, with their relative importance shifting across spatial scales and environmental contexts. Read the free Plain Language Summary for this article on the Journal blog.

Aim: Thousands of non‐native species have established populations and spread in outdoor environments (i.e., Naturalised), yet some populations or species only occur indoors, potentially due to unsuitable climates. We assessed the hypothesis that non‐native ants are more often restricted to indoor environments when they invade regions with climates dissimilar from their native regions. Furthermore, we forecasted how climate change could influence the naturalisation of indoor‐restricted non‐native ants. Location: Global. Methods: Using a global database of 323 non‐native ant taxa across 477 regions, we modelled how average climatic conditions in the native and invaded regions of each taxon determined whether they naturalised or were restricted indoors. We then modelled regional climatic suitability for the naturalisation of indoor‐restricted non‐native ants and projected future changes under climate change scenarios. We further assessed if climate change would facilitate the naturalisation of impactful non‐native ants using a global database describing their known impacts. Results: Non‐native ants originating from warm regions were more likely restricted indoors when introduced to cold regions. Under 2°C and 4°C of warming, the number of indoor‐restricted non‐native ant species projected to find suitable regional climates for naturalisation increased by an average of 0.08 (maximum = 1.2) and 0.27 (maximum = 3.7) taxa per region, respectively. These anticipated naturalisations include high‐impact non‐native ants, such as the Argentine ant Linepithema humile and are expected to increase socioeconomic and environmental impacts under both warming scenarios, particularly in European regions. Main Conclusions: Our findings suggest that indoor environments serve as microclimatic beachheads for biological invasions, especially in cold regions in the Northern Hemisphere. Failure to limit climate warming and inadequate biosecurity management in indoor environments may facilitate the naturalisation of non‐native ants, with costly repercussions on nature and society.

The writings of naturalists from two centuries past are brimming with accounts of the stark differences in the kinds and numbers of organisms encountered during the day and night as well as between the tropical and temperate zones. However, only recently have ecologists begun to systematically explore the geographic variation in the diel activity patterns of species on Earth. Examining data from 60 insect communities distributed globally, I find that the proportion of nocturnal species in a community declines from a peak of 36% at the equator to 8% at 60° latitude, while the proportion of diurnal species shows no significant trend. By contrast, the proportion of cathemeral (day- and night-active) species in a community increases poleward from 18% to 68% along the same gradient. These latitudinal trends in the partitioning of diel activity time among co-occurring insect species in communities broadly reflect previously documented biogeographic patterns in the global distributions of vertebrate species occupying different temporal niches. Since diel activity patterns shape insect community dynamics, uncovering their mechanistic basis and the roles of factors such as temperature, light and biotic interactions is vital for curbing insect declines in the Anthropocene.

1. Studies along broad spatial and habitat gradients evidence that organisms’ traits can influence community assembly through their impact on dispersal and environmental filtering. However, the role of traits in structuring local faunal communities within habitats remains poorly understood. In particular, the often-assumed role of traits in affecting the outcome of competition among animal species is rarely tested. 2. We coupled a field study with a mesocosm experiment to explore how ant species’ traits shaped competition and community structure, leveraging a small mangrove ecosystem which conceivably imposed minimal dispersal- and environmental filtering effects on ant community assembly. 3. We first surveyed the ant communities inhabiting 115 mangrove trees using over 2000 carbohydrate and protein baits, and directly measured multiple morphological, physiological (critical thermal maximum) and dietary (stable isotope trophic position) traits of all ant species. We then coupled co-occurrence network analyses with meta-analytical models to uncover the trait-based mechanisms structuring species co-occurrences in the field. Finally, in a mesocosm experiment, we reared 100 colonies of eight ant species from the mangrove over 30 days under different competition treatments to investigate trait-mediated effects of competition on ant colony performance. 4. Patterns of ant species co-occurrences and bait recruitment indicated strong competition for limited protein-rich resources. Accordingly, dissimilarities in three traits – eye size, pronotum width and antennal scape length – consistently explained species co-occurrences, suggesting that the communities were competitively assembled by a partitioning of resource acquisition strategies among species. Species co-occurrences were also to a lesser extent explained by similarities in critical thermal limits, suggesting mild environmental filtering. 5. In the mesocosm experiment, increasing hierarchical differences in eye size and pronotum width between neighbouring ant colonies exacerbated interspecific competitive effects on colony survival and growth. 6. Our results empirically demonstrate that traits linked to resource acquisition influence competition outcomes and community structure in ants. Importantly, they also suggest that the effects of species trait differences on competition are context-dependent: whereas dissimilarities in species’ traits facilitated resource partitioning in the mangrove, hierarchical differences in trait values distinguished species’ competitive abilities for shared resources in the mesocosms.