Bees are key pollinators that support global food production and plant biodiversity, yet wild pollinator populations are declining due to anthropogenic pressures, including habitat loss, pesticide use, and emerging disease. In honey bees (Apis mellifera), viral disease dynamics have been strongly influenced by the parasitic mite Varroa destructor, which vectors Deformed Wing Virus (DWV) and has altered viral community composition. DWV exists as multiple genotypes, most notably DWV-A and DWV-B, with recent studies suggesting a global shift towards DWV-B dominance. Here, we investigated the prevalence and viral load of DWV-A and DWV-B in honey bees and a wild bumblebee species across ten protected calcareous grassland sites in the UK to evaluate patterns of DWV genotype and the extent of potential pathogen spillover into wild bee populations. Contrary to expectations of DWV-A decline, both genotypes were highly prevalent in honey bees and bumblebees, with frequent co-detections observed. Notably, Bombus lapidarius exhibited higher DWV-A viral loads and similar prevalence to honey bees, indicating a possible role in the maintenance of DWV-A in UK grasslands. These findings challenge assumptions of a shift towards DWV-B predominance and highlight the importance of including wild pollinators in viral monitoring to better understand potential pathogen spillover and multi-host dynamics in managed and wild bee communities.
Ants are known for their well-developed exocrine system with glands distributed all over the body. Also their legs illustrate this impressive variety with 27 described glands so far. We here describe yet another leg gland: the pretarsus in all legs in workers of Paraponera clavata contains a paired cluster of glandular cells that has never been found in ants so far. Each cluster of this novel laterodistal pretarsus gland contains approximately 25 spherical secretory cells of which the accompanying duct cells open to the outside through the heavily sclerotized anterior pretarsal cuticle near the articulation with the arolium. The function of the gland remains unknown, none of the other ants that were checked possess this novel gland. Our finding thus extends the overall number of exocrine glands in ant legs to 28.
In social insects, alarm pheromones are particularly useful to protect the colony, by inducing nestmates recruitment and defensive behaviours when they are exposed to a danger. Although rarely species-specific, the chemical composition of these pheromones can vary depending on factors such as caste, colonial origin, and the age of individuals. Studying the alarm pheromone composition in invasive species is essential for identifying attractive compounds that could be used in the development of effective pheromone-based traps. Additionally, understanding how the chemical profile of this signal changes throughout the insect’s life cycle could enhance the design of such applications. The aim of this study was therefore to analyse the chemical composition of the venom gland of the invasive Yellow-legged hornet (Vespa velutina nigrithorax) in relation to the age of workers. Three age classes were compared: callows just after emergence (less than 24 h old), six-day-old callows and foragers of unknown age, assumed to be the oldest workers. Our results revealed that the newly emerged callows lacked certain compounds present in the older adults. In addition, specific chemical compounds were identified as key markers for each age group. These findings indicate that the venom gland composition of hornet workers changes with age, and that the signal such as the alarm pheromone emitted could convey different information depending on the age of the individual producing it.
Atta robusta is a narrow endemic leaf-cutting ant restricted to restinga habitats along Brazil’s southeastern coast. Despite its conservation status, little is known about its evolutionary history and genetic structure. Here, we investigate patterns of genetic variation in A. robusta using mitochondrial (COI–IGS–tRNALeu–COII) and nuclear (EF1alpha copy one) DNA markers sampled across its known range. We assess genetic diversity and population structure and infer relationships among haplotypes using Bayesian phylogenetic analysis and haplotype network reconstruction. We detected moderate haplotype diversity (Hd = 0.7789 for mtDNA and phased Hd = 0.6737 for EF1alpha F1), significant but incomplete population differentiation (ΦST up to 0.61), and a weak to moderate pattern of isolation by distance. Bayesian analyses recovered geographically associated haplotypes with shallow genetic divergence, while nuclear marker exhibited low relative to mitochondrial data. The star-like haplotype network is compatible with multiple demographic scenarios, but neutrality tests did not provide evidence for departures from demographic equilibrium. Overall, our results indicate shallow genetic structure and incomplete spatial differentiation across the species range. These findings highlight the importance of preserving remnant restinga habitats and maintaining landscape connectivity to safeguard genetic diversity in A. robusta and other habitat-specialist ants.
Herbivory is the predominant feeding strategy in Lepidoptera, whereas carnivory has evolved rarely. The life cycles of carnivorous species, however, remain poorly documented. Here, we confirm that Juditha odites (Riodinidae) butterflies oviposit near treehoppers tended by Dolichoderus bispinosus arboreal ants. We report that the caterpillars’ diet changes throughout ontogeny: early instars consume treehopper egg masses and nymphs on plants, followed by a shift after the third instar to feeding directly on ant brood inside the nest. This provides the first direct evidence of myrmecophagy in a parasitic Riodinidae, together with social integration and substrate-borne vibrations by the caterpillar. These findings expand the known natural history of carnivorous butterflies and reveal a previously undocumented multitrophic interaction involving butterflies, ants, and treehoppers on plants.
Bees (Apoidea: Anthophila) are recorded as common hosts of a diverse array of parasitic Diptera species, but information is widely scattered across the literature, limiting our knowledge of global bee-dipteran association patterns. Here, we retrieved published information on 453 bee-dipteran associations to test the role of life-history traits of hosts and parasites on such patterns. The 13 families and 37 genera of Diptera associated with bees are unevenly distributed across bee families within a specialized and modular network. The family Apidae was the most associated with parasitoids of adults, Colletidae were the most attacked by nest-entering larval parasitoids, Apidae and Megachilidae were the most attacked by non-nest-entering larval parasitoids, and cleptoparasites were more frequently observed attacking Andrenidae and Halictidae nests. The number of parasitic strategies, but not the richness of Diptera, was higher in fossorial species and both weakly depended on bee phylogeny. However, when considered singularly, the four parasitic strategies ((i) parasitoids of adults; (ii) nest-entering larval parasitoids; (iii) non-nest-entering larval parasitoids; and (iv) cleptoparasites) yielded moderate phylogenetic signals. Fossorial species were more associated with cleptoparasites, while the association rate of non-nest-entering larval parasitoids was higher in aerial-nesting bee species and in solitary bee species. In addition, fossorial bee species were found to be more specialised in their associate dipteran fauna. Despite the uneven distribution of studies across bee genera, our results suggest that these associations emerged through co-evolutionary processes, during which dipterans specialized and optimized their parasitic strategies based on the ecological traits of their host bees.
Larvae of many Volucella hoverflies are associated with nests of bumblebees and social vespids, where they may function as inquilines, scavengers, or predators. Although several Volucella species have been recorded from social vespid nests in Europe and Japan, larval records from Korean Vespula nests have not previously been documented. Here, we report the first Korean records of Volucella larvae from nests of two Vespula species, Vespula flaviceps flaviceps and Vespula koreensis koreensis. Larvae collected from these nests were identified using larval morphology and mitochondrial cytochrome c oxidase subunit I (COI) barcoding. Five larvae from a Vespula flaviceps flaviceps nest and 11 of 12 larvae from a Vespula koreensis koreensis nest were identified as Volucella pellucens tabanoides Motschulsky, 1859, whereas the remaining larva from the latter nest was identified as Volucella linearis (Walker 1849). We combine these records with previously reported Vespa mandarinia-associated Volucella records from Korea to provide external larval morphology, adult habitus images, a COI maximum-likelihood tree, and a diagnostic key to four Korean Volucella species associated with nests of social vespids. These records expand the known host associations of East Asian Volucella and suggest that Volucella–Vespula nest associations are shared, at least in part, between Japan and Korea.
Myrmecophily is widespread among arthropods but remains poorly documented in spiders, particularly in Mygalomorphae. Tarantulas (Theraphosidae) have not previously been shown to form true myrmecophilous associations, with existing records limited to anecdotal observations. Here, we provide the first robust evidence of myrmecophily in a tarantula, based on combined field and experimental data. Fieldwork in the Ñacuñán Biosphere Reserve (Monte Desert, Argentina) revealed that individuals of a species of Catumiri Guadanucci 2004 inhabit nests of the leaf-cutting ant Acromyrmex lobicornis Emery 1887. Of 45 excavated nests, 16 (35.5
Mutualist ants have been shown to influence the morphological evolution of trophobiotic root mealybugs in interesting ways. This study evaluates the morphology of setae across all described root mealybugs (Hemiptera: Rhizoecidae, Xenococcidae) and assesses whether there is a relationship between the types of setae represented in a species and their status as an obligate ant mutualist (i.e., associated vs. free-living). Myrmecophilous root mealybugs are indeed found to have unusual setae in addition to the simple flagellate body setae that all species possess, and such atypical setae are a rarity among free-living species. Several of the atypical setal forms are strictly found in myrmecophilic species. Clavate and spiniform setae are distributed among both myrmecophiles and free-living species but, of the two, only clavate setae were found to have a significant relationship with ant association. The forms of setae associated with myrmecophily, specifically sensory-tipped setae, show some convergence between members of Rhizoecidae and Xenococcidae, and furthermore even among the associates of herdsmen ants from the family Pseudococcidae. Convergent traits represent similarity due to shared ecology rather than shared history, but atypical setae have lent justification for the establishment of multiple genera in the family Rhizoecidae, suggesting that myrmecophily may have a confounding influence on root mealybug taxonomy. We describe a new species, Williamsrhizoecus hisopo Schneider LaPolla sp. nov., discovered in association with Acropyga exsanguis from Panama and discuss the potential significance of unusual setae in the context of ant association.
Host-associated microbes can impact host fitness, and it is therefore important to uncover the drivers of variation among hosts in their associated microbes. In social insects, microbiome composition differs based on both reproductive role and behavioral task. Here, we asked whether reproductive role or behavioral task is more important in determining the diversity and composition of host-associated microbes in the harvester ant Veromessor andrei. Specifically, we compared the bacterial communities between workers and reproductives by sequencing the 16 S rRNA gene region. We further compared the bacterial communities between workers that are foragers and those that perform nest maintenance, as well as between reproductives that are male alates and those that are female alates. We found that reproductive role was a better predictor of bacterial communities than behavioral task. Workers and reproductives differed in their bacterial communities. However, different types of workers (foragers and nest maintenance workers) and different types of reproductives (males and females) did not differ from one another in their bacterial communities. Our findings suggest that differences in reproductive roles are a better predictor for differences in microbial communities than behavioral tasks.
Termite workers serve as an auxiliary defensive force in the colony against natural predators; however, it remains unclear whether the presence of the queen affects their aggressive behaviors. Here, we experimentally assessed the aggressive responses of termite workers toward ant intruders. Our results showed that in Reticulitermes chinensis, the relatively high levels of worker aggressive behavior toward enemy ants depended strictly on the presence of the queen, rather than the presence of soldiers. Workers exhibited a significantly higher attack frequency in queen-present groups when exposed to an intruding Camponotus herculeanus ant. In contrast, the presence or absence of soldiers had no effect on worker aggression. Furthermore, specific workers that subsequently differentiated into ergatoid neotenics exhibited significantly lower pre-differentiation attack levels and higher escape levels compared to other workers. Our results demonstrate that worker defensive behavior is highly plastic: the queen promotes attack, but in her absence, workers shift to an escape-prone strategy that may be adaptive under different social conditions. This study provides new insights into the highly adaptive behavioral plasticity of workers in eusocial species with a specialized soldier caste.
The Optimal Defense Hypothesis (ODH) posits that investment in defense is proportional to the value of what is defended, predicting that the most valuable resources should have the strongest defenses. We determined whether an obligate ant-plant mutualism aligns with the predictions of the ODH and tested the impact of sporadic rainfall in this process. Sampling was performed in a tropical deciduous forest on the Yucatán Peninsula, Mexico, on Vachellia globulifera plants and one of their obligate mutualist ant species, Pseudomyrmex ferruginosus. We sampled ant activity before, during, and after an experimental rain event in branches with housing and food rewards (domatia and leaves with nectaries and food bodies) and in branches with only domatia (swollen spines). We found that: (a) before the experimental rain, the number of patrolling events was two-fold higher in branches with spines and leaves compared with branches with only spines, (b) during the experimental rain, ants on branches with spines and leaves stayed on the branch at a higher rate compared to branches with only spines, and (c) right after the experimental rain, while branches with the two types of resources reach levels of ant activity almost identical to those observed before the rain (90
Mutualistic interactions between ants and hemipterans represent well-established examples of symbiosis. The interaction between ants of the genus Acropyga and the mealybugs they tend on roots is both permanent and obligatory. In this relationship, the honeydew produced by the mealybugs is exchanged for the protection provided by the ants, a process facilitated by several behaviors that promote cooperation between the species. We conducted systematic observations of interactions between workers of the ant Acropyga fuhrmanni and the hemipterans Neochavesia caldasiae that they tend across seven colonies in the laboratory. We reassessed the behavior previously termed “appeasement boxing” consisting of a rapid succession of movements of the mealybug abdominal apex which was erroneously attributed to the function of repelling the ant when the mealybug was disturbed during feeding. The behavior was recorded in multiple contexts and, in most cases, did not lead to the workers being repelled. Instead, this boxing behavior emerged within contexts of exploration, recognition, collection, and transportation of the mealybugs, frequently preceding their active manipulation by the ants. Our results indicate a multifunctional character, potentially associated with recognition, collection, and prioritization of transport. This finding warrants the revision of the expression “appeasement boxing” to “abdominal signalling” to more accurately reflect the function of this behavior within the close mutualism between Neochavesia caldasiae and Acropyga fuhrmanni.
Tropical islands host distinct lifeforms and ecological interactions as a result of their geographic isolation and limited terrestrial area. Ant–hemipteran trophobiosis in these tropical ecosystems create localised resource concentrations that attract a range of associated arthropods. However, the spatial associations and behavioural strategies of predators exploiting these systems remain poorly understood. Here, I examine the association between the Iridescent Sunda Jumper Cosmophasis rakata Żabka Waldock (Araneae: Salticidae), the weaver ant Oecophylla smaragdina (Fabricius) (Hymenoptera: Formicidae), and true bugs (Hemiptera: Sternorrhyncha and Auchenorrhyncha) in human-modified habitats on Havelock Island (Andaman and Nicobar Islands, India). This study combines spatial analyses with qualitative behavioural observation to examine their ecological relationship. Surveys showed that all three taxa co-occurred more frequently than expected by chance. Focal observations of C. rakata helped document 26 discrete behaviours, within behavioural categories such orientation, scanning, locomotion, signalling, maintenance, avoidance, and predation by C. rakata on both hemipterans and weaver ants within actively patrolled aggregations. These observations indicate that C. rakata regularly exploits trophobiotic aggregations and accesses weaver ant-defended resources through behavioural strategies. It also highlights the potential role of behavioural strategies in facilitating predator integration into resource rich social arthropod systems.
Cuticular hydrocarbons (CHCs) play essential roles in social insects, including water retention, chemical communication, and conspecific recognition. In this study, gas chromatography coupled with mass spectrometry (GC-MS) analyses were used to identify the CHC profiles of six social wasp species from the Brazilian Amazon: Agelaia pallipes (Olivier, 1792), Apoica pallida (Olivier, 1792), Brachygastra augusti (de Saussure, 1854), Polistes canadensis (Linnaeus, 1758), Polybia rejecta (Fabricius, 1798), and Synoeca surinama (Linnaeus, 1767). The species differed in their CHC composition, ranging from five compounds in P. rejecta to 17 in A. pallida, with the total number of identified compounds varying between seven and 21, respectively. The predominant compounds found in the samples were alkanes, alkenes, and particular compounds like n-heptacosane, n-nonacosane, and cis-vaccenic acid, suggesting roles in water retention and colony member recognition. The wasps also exhibited fatty acids and esters, which may be related to communication and defense. Additionally, the presence of six unidentified compounds indicates the existence of bioactive substances that require further investigation. This study broadens our understanding of the chemical diversity of CHCs in social wasps and their potential ecological and behavioral functions.
The Western honey bee (Apis mellifera) forms large colonies which represent organisms in their own right, known as superorganisms. Although this species is among the most extensively studied insects, competing explanations persist regarding fundamental characteristics like colonial lifespan. This review refutes the notion of colonial immortality due to an inverted identification of parent and offspring, advocating instead for viewing a traditional honey bee colony as a matrilineage of mortal superorganisms. By refining the colonial life cycle to trace zygotic, embryonic, fetal, juvenile, and adult stages during superorganismal ontogeny, we extend the animal-superorganism analogy to reveal a viviparous organism engaged in strictly sexual reproduction and complex maternal care. Furthermore, analyzing the multiple pathways to female reproduction indicates that swarming in itself does not represent reproduction, as it precedes fertilization. Under this framework, the prime swarm allows the maternal superorganism to survive reproduction, whereas afterswarms serve to multiply offspring within a single reproductive cycle. These insights have implications for honey bee parasitology, demographic monitoring, and beekeeping management and provide a more rigorous foundation for the superorganism concept applicable to sexually reproducing social insects with queen supersedure or turnover.
In social insects, colonies are composed of numerous individuals that cooperate to form a unified entity with coordinated control mechanisms. Because colony-level behaviors emerge from the accumulation of interactions among individuals, colony size can strongly influence traits such as resource allocation and caste composition. Therefore, to understand the regulatory mechanisms and investment strategies of colonies, it is essential to monitor their dynamics with explicit consideration of colony size. However, in subterranean termites, colony size estimation remains challenging due to their cryptic nesting habits. Even under laboratory rearing conditions, assessing colony size often damages individuals or nest structures, making repeated longitudinal monitoring difficult. Here, we developed a non-invasive method for estimating colony biomass in laboratory-reared colonies of Reticulitermes speratus based on CO₂ emissions. By recording CO₂ concentrations for 90 min in a sealed container, we found a strong correlation between total termite biomass and CO₂ output (r = 0.982, R2 = 0.965), whereas correlations with nest volume proxies were weaker. Repeated measurements every two days over four sessions revealed no significant decline in estimated biomass, and a non-inferiority test confirmed that CO₂ assays did not reduce colony biomass. This approach provides a practical solution for repeated, non-invasive estimation of termite colony biomass, enabling longitudinal studies of caste differentiation, reproductive transitions, and behavioral regulation in relation to colony size, as reflected by colony biomass. Because CO₂ emissions from respiration are a universal biological trait, the method may also be applicable to other termite species and more distantly related taxa.
Males in social Hymenoptera have historically been perceived as non-contributing members of the female-centric colony, even earning the moniker of ‘ethological non-entity’ by famed entomologist W. M. Wheeler. This perspective has shifted more recently as scientific advances in the field have further clarified the role of male Hymenoptera within the colony. Despite this, many questions remain regarding the significance of male hymenopterans to their colony. Here, we re-evaluate previous, historical misconceptions about male Hymenoptera by reviewing various aspects through which males may be shaping colony and population dynamics based on more current research. More specifically, we review male behaviors (e.g. male aggression and territoriality, mate guarding, brood care), male copulatory effects (e.g. sperm competition, parent-of-origin-effects) and the effects of male haploidy in selection. However, the historical disinterest in male hymenopterans may be continuing to shape the field, resulting in publication and taxonomic biases that are potentially impeding progress within this field. Broadly, this review highlights the need for a more nuanced perspective on the role of the male hymenopteran and pushes back against the idea of males as an ‘ethological non-entity’. We are convinced that this is an emerging field that is poised to reveal greater insights into the inner workings of social insect societies.
In social insects, nutrient acquisition can emerge from the integration of processes operating at both individual and colony levels. We hypothesize that food storage in termite mounds enables microbial predigestion of plant material, thereby enhancing nutrient acquisition at the colony level. Here, we investigate how food storage and associated microbial communities contribute to nutrient processing in the Neotropical mound-building termite Velocitermes heteropterus. We analyzed nest architecture, carbon and nitrogen content of stored food, gut contents, and the taxonomic and functional profiles of microbial communities associated with termite guts and nest substrates. The mounds exhibited a conical shape with a sponge-like internal structure in which dry grass fragments were stored. Satellite nests connected to larger mounds suggest a polydomous organization that may facilitate spatial resource allocation. Stored food displayed significantly higher C: N ratios than senescent plant material, indicating modification of nutrient stoichiometry prior to ingestion. Microbial communities differed markedly between nest substrates and termite guts. The nest-associated microbiota was enriched in Proteobacteria and Actinobacteria and showed a higher predicted abundance of functions associated with hemicellulose degradation, particularly xylanases. In contrast, the gut microbiota was associated with cellulolytic and starch-degrading functions. Microscopic analyses revealed plant fragments and fungal propagules in both workers and soldiers. Together, these findings indicate that food storage mediates a functional separation between external microbial predigestion and internal gut digestion, forming an integrated system that enhances nutrient acquisition from recalcitrant grass substrates.
