Weaver Ant Oecophylla Smaragdina Research Articles

Olfaction foraging in visually oriented tropical arboreal ants Oecophylla smaragdina: Implications for insect predation studies using artificial sentinel prey

AbstractBecause of the brief and cryptic nature of predatory behavior, sentinel prey has been widely adopted as an indirect way to identify predators and understand trophic interactions. However, sentinel prey presents only static visual cues, potentially biasing toward visually oriented predators while ignoring those that utilize other sensory cues for foraging. Despite this, the effectiveness of sentinel prey has rarely been tested. In this study, we focused on the weaver ant Oecophylla smaragdina Fabricius (Hymenoptera: Formicidae), a keystone predator widespread in the Asian and Australian tropics. As this species has large eyes and is known to visually navigate in its arboreal habitats, we hypothesized that it relies on visual cues to forage and that its predatory behavior will be captured by caterpillar‐shaped sentinel prey. Ants were collected as colonies, and preference trials on baits were conducted using combinations of olfactory and static visual cues, including the caterpillar shape. Surprisingly, O. smaragdina showed little or no preference for baits in the absence of olfactory cues and did not differentiate the shapes of baits regardless of olfactory cues. Our results indicate that O. smaragdina is likely to make predatory decisions based primarily on olfactory cues, whereas visual cues might be used for other behaviors. Furthermore, O. smaragdina is likely to be left out by the predation studies using sentinel prey models, which is particularly alarming considering the dominant role of this species in the trophic interactions of tropical rainforests. Our study demonstrates that morphological characteristics, arboreal habitats, and visually oriented behavior do not necessarily suggest the use of static visual cues for predatory decisions. We suggest that sentinel prey models should not be used alone when the dominant predators are unlikely to use visual cues to make predatory decisions.

EcophyllaStudy of Nesting behavior adaptability in Asian weaver ant Oecophylla smaragdina Fabricius (Hymenoptera: Formicidae) with respect to reproductive cycle and floral diversity

ecophyllaStudy of Nesting behavior adaptability in Asian weaver ant Oecophylla smaragdina Fabricius (Hymenoptera: Formicidae) with respect to reproductive cycle and floral diversity

A simple mechanism for collective decision-making in the absence of payoff information

Animals are often faced with time-critical decisions without prior information about their actions' outcomes. In such scenarios, individuals budget their investment into the task to cut their losses in case of an adverse outcome. In animal groups, this may be challenging because group members can only access local information, and consensus can only be achieved through distributed interactions among individuals. Here, we combined experimental analyses with theoretical modeling to investigate how groups modulate their investment into tasks in uncertain conditions. Workers of the arboreal weaver ant Oecophylla smaragdina form three-dimensional chains using their own bodies to bridge vertical gaps between existing trails and new areas to explore. The cost of a chain increases with its length because ants participating in the structure are prevented from performing other tasks. The payoffs of chain formation, however, remain unknown to the ants until the chain is complete and they can explore the new area. We demonstrate that weaver ants cap their investment into chains, and do not form complete chains when the gap is taller than 90 mm. We show that individual ants budget the time they spend in chains depending on their distance to the ground, and propose a distance-based model of chain formation that explains the emergence of this tradeoff without the need to invoke complex cognition. Our study provides insights into the proximate mechanisms that lead individuals to engage (or not) in collective actions and furthers our knowledge of how decentralized groups make adaptive decisions in uncertain conditions.

On the behavioural biology of a morpho-variant of Myrmaplata plataleoides (O. Pickard-Cambridge, 1869) (Araneae: Salticidae) with taxonomic notes

Abstract We hereby report an isolated population of a rare morpho-variant of the ant-mimicking jumping spider Myrmaplata plataleoides (O. Pickard-Cambridge, 1869) from Hazaribagh Wildlife Sanctuary, Hazaribagh, Jharkhand, India, which is also the first record of this species from the state of Jharkhand, India. Descriptions of both male and female spiders, the female’s exuviae, its eggs and habitat are presented. We have studied its moulting, feeding and sexual behaviour in detail, and have recorded various behavioural aspects that were never documented before, such as debris-rolling behaviour, photokinetic response, starvation response and oxygen deprivation response. We here report the occurrence of this spider near the colonies of the ground-nesting ant Camponotus compressus (Fabricius, 1787). This spider is known to mimic the Asian weaver ant Oecophylla smaragdina (Fabricius, 1775), which are greenish orange to red in colour. Specimens collected by us are dark brown to black in coloration whereas the commonly reported specimens are often greenish orange to red. We propose that the darker coloration would have been naturally selected in this isolated population of M. plataleoides as an adaptation to coexist with C. compressus, which is also black in coloration and abundant around the spiders. Study of the moulting behaviour of the morpho-variant further reveals the display of a novel mechanism of ant mimicry among these spiders which we have named as temporal myrmecomorphy. Temporal myrmecomorphy has been proposed to be a protective mechanism used by a harmless mimic against the attacks of the aggressive models so that it can co-exist with the models. Present study establishes the usefulness of a morpho-variant as an important model in understanding the evolution and behaviour of a species holistically.

Formicincola oecophyllae gen. nov. sp. nov., a novel member of the family Acetobacteraceae isolated from the weaver ant Oecophylla smaragdina.

In this study, a novel bacterium designated F3b2T was isolated from the gut sample of weaver ant Oecophylla smaragdina and characterised. Strain F3b2T was a Gram-negative, aerobic, non-motile, ovoid-shaped bacterium and grows optimally at 28-30°C. Its major respiratory quinone is ubiquinone 10 (Q-10) and the major fatty acids are C18:1 ω7c, C19:0 cyclo ω8c and C16:0, representing 85% of the total fatty acids. The 16S rRNA gene sequence of strain F3b2T was highest in similarity to that of Oecophyllibacter saccharovorans DSM106907T and Swingsia samuieinsis NBRC 107927T at 94.35% and 91.96%, respectively. A 16S rRNA gene-based phylogenetic analysis and a core genes-based phylogenomic analysis placed strain F3b2T in a distinct lineage in the family Acetobacteraceae. The phylogenetic placement was supported by lower than species delineation threshold average nucleotide identity (ANI) (≤ 70.2%), in silico DNA-DNA hybridization (DDH) (≤ 39.5%) and average amino acid identity (AAI) (≤ 63.5%) values between strain F3b2T and closest neighbours. These overall genome relatedness indices also supported the assignment of strain F3b2T to a novel genus within Acetobacteraceae. The genome of strain F3b2T was 1.96Mb with 60.4% G + C DNA content. Based on these results, strain F3b2T represented a novel taxon of Acetobacteraceae, for which we proposed the name Formicincola oecophyllae gen. nov. sp. nov., and strain F3b2T (= LMG 30590T = DSM 106908T = NBRC 113640T = KCTC 62951T) as the type strain.

Oecophylla smaragdina (Hymenoptera: Formicidae) and Odontotermes sp. (Isoptera: Termitidae) a potential source of antioxidant: the two most preferred edible insects of Arunachal Pradesh, India

Antioxidant potential of weaver ant Oecophylla smaragdina (adult & brood) and termite Odontotermes sp the two common species of insects used as food by tribes of Arunachal Pradesh and elsewhere in India. Our findings highlight the antioxidant potential of these two insects. DPPH• scavenging activity IC50 (µg/mL) ranged from 59.56 (weaver ant adult) to 66.30 (termite). Termite species scored higher ABTS•+ scavenging activity (IC50: µg/mL), Ferric reducing power (TPEE µg/g) and phenolics (mg GAE/g) (18.70, 36.60 and 626.92) than weaver ant adult (52.57, 211.21 and 369.69) and weaver ant brood (33.34, 114.32 and 486.04). On the other hand, weaver ant adult scored higher flavonoids (mg RTE/g) (663.43) than its brood (387.19) and termite species (58.04). Weaver ant brood contained substantial amounts of phenolics and flavonoids, comparatively higher than phenolics of weaver ant adult and flavonoids of termite. These two insects may serve as an ideal dietary food supplement for handling oxidative stress and as a replacement for some conventional food products. However, further study is needed to find out the bioactive compound at the individual species level.

Plasmid localization of sole rrn operon in genomes of Oecophyllibacter saccharovorans (Acetobacteraceae)

The bacterium Oecophyllibacter saccharovorans of family Acetobacteraceae is a symbiont of weaver ant Oecophylla smaragdina. In our previous study, we published the finding of novel O. saccharovorans strains Ha5T, Ta1 and Jb2 (Chua et al. 2020) but their plasmid sequences have not been reported before. Here, we demonstrate for the first time that the sole rrn operon of their genomes was detected on a 6.6 kb circular replicon. This replicon occurred in high copy number, much smaller size and lower G + C content than the main chromosome. Based on these features, the 6.6 kb circular replicon was regarded as rrn operon-containing plasmid. Further restriction analysis on the plasmids confirmed their circular conformation. A Southern hybridization analysis also corroborated the presence of 16S rRNA gene and thus the rrn operon on a single locus in the genome of the O. saccharovorans strains. However, similar genome architecture was not observed in other closely related bacterial strains. Additional survey also detected no plasmid-borne rrn operon in available genomes of validly described taxa of family Acetobacteraceae. To date, plasmid localization of rrn operon is rarely documented. This study reports the occurrence of rrn operon on the smallest bacterial plasmid in three O. saccharovorans strains and discusses its possible importance in enhancing their competitive fitness as bacterial symbiont of O. smaragdina.

Oecophyllibacter saccharovorans gen. nov. sp. nov., a bacterial symbiont of the weaver ant Oecophylla smaragdina

In this study, bacterial strains Ha5T, Ta1, and Jb2 were isolated from different colonies of weaver ant Oecophylla smaragdina. They were identified as bacterial symbionts of the ant belonging to family Acetobacteraceae and were distinguished as different strains based on distinctive random-amplified polymorphic DNA (RAPD) fingerprints. Cells of these bacterial strains were Gram-negative, rod-shaped, aerobic, non-motile, catalase-positive and oxidase-negative. They were able to grow at 15-37°C (optimum, 28-30°C) and in the presence of 0-1.5% (w/v) NaCl (optimum 0%). Their predominant cellular fatty acids were C18:1ω7c, C16:0, C19:0ω8c cyclo, C14:0, and C16:0 2-OH. Strains Ha5T, Ta1, and Jb2 shared highest 16S rRNA gene sequence similarity (94.56-94.63%) with Neokomagataea tanensis NBRC106556T of family Acetobacteraceae. Both 16S rRNA gene sequence-based phylogenetic analysis and core gene-based phylogenomic analysis placed them in a distinct lineage in family Acetobacteraceae. These bacterial strains shared higher than species level thresholds in multiple overall genome-relatedness indices which indicated that they belonged to the same species. In addition, they did not belong to any of the current taxa of Acetobacteraceae as they had low pairwise average nucleotide identity (< 71%), in silico DNA-DNA hybridization (< 38%) and average amino acid identity (< 67%) values with all the type members of the family. Based on these results, bacterial strains Ha5T, Ta1, and Jb2 represent a novel species of a novel genus in family Acetobacteaceae, for which we propose the name Oecophyllibacter saccharovorans gen. nov. sp. nov., and strain Ha5T as the type strain.

Social Complexity and Brain Evolution: Comparative Analysis of Modularity and Integration in Ant Brain Organization

The behavioral demands of living in social groups have been linked to the evolution of brain size and structure, but how social organization shapes investment and connectivity within and among functionally specialized brain regions remains unclear. To understand the influence of sociality on brain evolution in ants, a premier clade of eusocial insects, we statistically analyzed patterns of brain region size covariation as a proxy for brain region connectivity. We investigated brain structure covariance in young and old workers of two formicine ants, the Australasian weaver ant Oecophylla smaragdina, a pinnacle of social complexity in insects, and its socially basic sister clade Formica subsericea. As previously identified in other ant species, we predicted that our analysis would recognize in both species an olfaction-related brain module underpinning social information processing in the brain, and a second neuroanatomical cluster involved in nonolfactory sensorimotor processes, thus reflecting conservation of compartmental connectivity. Furthermore, we hypothesized that covariance patterns would reflect divergence in social organization and life histories either within this species pair or compared to other ant species. Contrary to our predictions, our covariance analyses revealed a weakly defined visual, rather than olfactory, sensory processing cluster in both species. This pattern may be linked to the reliance on vision for worker behavioral performance outside of the nest and the correlated expansion of the optic lobes to meet navigational demands in both species. Additionally, we found that colony size and social organization, key measures of social complexity, were only weakly correlated with brain modularity in these formicine ants. Worker age also contributed to variance in brain organization, though in different ways in each species. These findings suggest that brain organization may be shaped by the divergent life histories of the two study species. We compare our findings with patterns of brain organization of other eusocial insects.

Antennal sensilla of the weaver ant Oecophylla Smaragdina (F.)-Males and Females sense differently?

Antenna of males and female insects are distinct in morphology and function, and such differences exist in the weaver ant Oecophylla smaragdina (F.). In this ant, behaviour is predominantly olfactory driven. Foraging, nursing, feeding, defense etc., are the predominant female behaviour. Males are in less numbers and are seldom in the colony. This study explores the sexual dimorphism in O. smaragdina with respect to antennal morphology, morphometry and sensilla profile, which are often considered key components of the peripheral sensory system. Scanning electron microscopic (SEM) studies revealed that the sensilla profile on the antenna probably reflects the sensitivity. Antennal morphology and sensilla profile differ in males and females. Sensilla repertoire of the females (major worker) is different in the number and types of chemosensilla. Sensilla basiconica type1 and type 2, sensilla trichoidea curvata, sensilla ampullacea and sensilla coeloconica were the abundant ones observed on the female antenna. Males have sparse sensilla, and its putative sensilla basiconicais strikingly different. The results suggest that the sensilla profile can be reflective of the behavioral repertoire in these ants.

Intercolony distance predicts the decision to rescue or attack conspecifics in weaver ants

Group formation and recognition mechanisms can strongly influence the decision to cooperate or attack in animal societies. Therefore, testing how individuals recognize group membership, and the decision to cooperate or attack during social interactions is critical to understanding the evolution of sociality. We explore decision-making in the weaver ant Oecophylla smaragdina, a highly territorial and also cooperative species. Here, we report a previously undescribed rescue behavior for weaver ants, and determine the role of distance and group membership in residents’ decisions to either rescue or attack conspecifics in distress. First, we tested if residents preferentially rescued nestmates and attacked non-nestmates. Our results show that rescue was more likely for nestmates; however, surprisingly, conspecifics from neighboring colonies were rescued in 43% of the distress trials. Furthermore, attacks became more frequent as distance between colonies increased showing a dear enemy effect, which may be explained by familiarity, odor recognition, and/or relatedness. Our work exploring the factors that influence the decision to rescue or attack provides novel evidence to understand the underlying selective pressures that shape decisions of cooperation or conflict in highly cooperative societies.

Microbial Community Composition Reveals Spatial Variation and Distinctive Core Microbiome of the Weaver Ant Oecophylla smaragdina in Malaysia

The weaver ant Oecophylla smaragdina is an aggressive predator of other arthropods and has been employed as a biological control agent against many insect pests in plantations. Despite playing important roles in pest management, information about the microbiota of O. smaragdina is limited. In this work, a number of O. smaragdina colonies (n = 12) from Malaysia had been studied on their microbiome profile using Illumina 16S rRNA gene amplicon sequencing. We characterized the core microbiota associated with these O. smaragdina and investigated variation between colonies from different environments. Across all 12 samples, 97.8% of the sequences were assigned to eight bacterial families and most communities were dominated by families Acetobacteraceae and Lactobacillaceae. Comparison among colonies revealed predominance of Acetobacteraceae in O. smaragdina from forest areas but reduced abundance was observed in colonies from urban areas. In addition, our findings also revealed distinctive community composition in O. smaragdina showing little taxonomic overlap with previously reported ant microbiota. In summary, our work provides information regarding microbiome of O. smaragdina which is essential for establishing healthy colonies. This study also forms the basis for further study on microbiome of O. smaragdina from other regions.

Insects as source of angiotensin converting enzyme inhibitory peptides

Hypertension is well known as one of the major risk for cardiovascular diseases which annually affect millions of people. The angiotensin converting enzyme (ACE) plays a key role in blood pressure regulation process. Indeed, hypertension treatment by synthetic ACE inhibitors (e.g. captopril, lisinopril and ramipril) is effective; however, their use can cause serious side effects, such as hypotension, cough, reduced renal function and angioedema. Thus, research was focused on natural ACE inhibitory peptides sources such as foodstuffs and also, more recently, edible insects. In the last decades, ACE inhibitory activity has been detected in protein hydrolysates from insect species belonging to the orders of Coleoptera, Diptera, Hymenoptera, Lepidoptera and also Orthoptera. Further investigations led to identify specific ACE inhibitory peptides from the silkwormBombyx mori (Lepidoptera: Bombycidae), the yellow mealwormTenebrio molitor (Coleoptera: Tenebrionidae), the cotton leafwormSpodoptera littoralis (Lepidoptera: Noctuidae) and also from the weaver antOecophylla smaragdina (Hymenoptera: Formicidae). Even if ACE inhibitory activity of these bioactive peptides has beenin vitro assayed and is comparable to those of some bioactive peptides derived from other animal protein sources, thein vivo effectiveness of most of these bioactive peptides still needs to be confirmed. The aim of this review is to present an outline of the currently available data on the potential use of insects for hypertension treatment with a focus on the ACE inhibitory peptides identified in these invertebrates to date.

Molecular probe, colony structure and SEM of antennal sensillae substantiate intermediate workers of Oecophylla smaragdina (Fab.) as typical worker

The polymorphic colony of arboreal weaver ant Oecophylla smaragdina Fabricius has three categories of workers designated as typical, major and minor. The colony structure fluctuated sharply with seasons but the numerical ratio of worker castes always remained as 65:25:10. Typical workers have highest number of sensillae/unit area on the terminal segment of antenna and all the above characters established their role in the colony different from major and minor workers. Microsatellite DNA analysis of worker castes indicated high degree of genetic diversity, heterozygocity and genetic polymorphism among three worker castes, reproductive males and females. Mitochondrial DNA analysis proved that all the three categories of worker castes were developed from eggs of a single queen.

Macronutrient Exchange Between the Asian Weaver Ant Oecophylla smaragdina and Their Host Plant

Ant–plant interactions have mainly been considered as a protection mutualism where ants increase plant performance through protection from herbivory. However, host plants may also benefit from nutrients deposited by ants. Nitrogen limits the plant growth in most terrestrial ecosystems and the nutrient exchange between ants and plants may be an important mechanism operating in ant–plant interactions. In this study, we quantified the exchange of macronutrients (carbon and nitrogen) between ants and plants, using the Asian weaver ant Oecophylla smaragdina as a model species in a mango agroecosystem. A method was developed with which the amount of nitrogen retrieved to their host trees could be predicted by the trail density of O. smaragdina. Ant nutrient consumption was calculated based on data on O. smaragdina abundance and per capita consumption rates obtained in laboratory colonies. On a yearly basis, the influx of nitrogen to the host tree, originating from captured prey, averaged 14.4 (range 8.0–46.4) kg N ha−1 y−1. The loss of carbon from the host tree due to ant consumption of exudates from nectaries and tended homopterans averaged 278.1 (range 149.3–939.9) kg C ha−1 y−1. O. smaragdina may provide their host plant with a significant source of nitrogen albeit a substantial amount of carbon is consumed from the host plant. This study reveals that the flow of nutrients between ants and plants may play a critical and underestimated role in ant–plant mutualisms.

The Antsy Social Network: Determinants of Nest Structure and Arrangement in Asian Weaver Ants.

Asian weaver ants (Oecophylla smaragdina) are arboreal ants that are known to form mutualistic complexes with their host trees. They are eusocial ants that build elaborate nests in the canopy in tropical areas. A colony comprises of multiple nests, usually on multiple trees, and the boundaries of the colony may be difficult to identify. However, they provide the ideal model for studying group living in invertebrates since there are a definite number of nests for a given substrate, the tree. Here, we briefly examine the structure of the nests and the processes involved in the construction and maintenance of these nests. We have described the spatial arrangement of weaver ant nests on trees in two distinct tropical clusters, a few hundred kilometres apart in India. Measurements were made for 13 trees with a total of 71 nests in the two field sites. We have considered a host of biotic and abiotic factors that may be crucial in determining the location of the nesting site by Asian weaver ants. Our results indicate that tree characteristics and architecture followed by leaf features help determine nest location in Asian weaver ants. While environmental factors may not be as influential to nest arrangement, they seem to be important determinants of nest structure. The parameters that may be considered in establishing the nests could be crucial in picking the evolutionary drivers for colonial living in social organisms.

Quantification of Ant Manure Deposition in a Tropical Agroecosystem: Implications for Host Plant Nitrogen Acquisition

Ants are functionally important organisms in most terrestrial ecosystems. Being ubiquitous and abundant, ant communities can affect the availability of resources to both primary and secondary consumers. As nitrogen is a limiting nutrient for plant growth in most terrestrial ecosystems, deposition of ant manure may augment the host plants’ acquisition of nitrogen. In this study, we quantified the manure deposited by colonies of the Asian weaver ant Oecophylla smaragdina. We developed a method to estimate the amount of manure deposited in host trees (Mangifera indica) based on the trail activity of O. smaragdina. The rate of manure deposition was on average 62.3 kg dw ha−1 y−1, of which 0.2 kg ha−1 y−1 was deposited as urea-N, a nutrient that may be absorbed directly through the leaves, and 1.9 kg ha−1 y−1 was deposited as total nitrogen. Furthermore, ants given access to sucrose solution increased their rate of manure deposition significantly, suggesting that nectaries and/or trophobionts may play a major role in the production of ant manure. This study reveals that O. smaragdina can supply a significant amount of nitrogen to their host plants. In light of their remarkable abundance, the manure deposition by ants may have a hitherto unappreciated impact on the allocation of nutrients within their ecosystem.

Size and the Composition of the Colony of Weaver Ants (Oecophylla smaragdina) and Ecology Role Toward the Palm

Size and the Composition of the Colony of Weaver Ants (Oecophylla smaragdina) and Ecology Role Toward the Palm

Acid, silk and grooming: alternative strategies in social immunity in ants?

Parasites are an important force in evolution, driving the need for costly resistance mechanisms. The threat from disease is potentially high in group-living species such as social insects, which have accordingly evolved behavioural and chemical defences that vary between species depending on their life histories. Several ant genera have lost a key exocrine antimicrobial defence, the metapleural gland, and yet are still able to thrive in environments abundant with parasites. We investigate, in species lacking the metapleural gland, how the production of antimicrobial venom, grooming behaviours and the use of potentially antimicrobial larval silk may have evolved as alternative antiparasite defences. We focus on the Australasian weaver ant Oecophylla smaragdina and compare this to Polyrhachis weaver ants. We show that the production of venom by O. smaragdina workers is important for disease resistance but that the presence of larval silk is not, and that workers use their acidic venom to maintain nest hygiene. The grooming defences of O. smaragdina differ between castes, with minor workers allogrooming more and major workers showing greater upregulation of grooming in response to parasites. Chemical and behavioural defences differ interspecifically between O. smaragdina and Polyrhachis, with O. smaragdina appearing to rely primarily on its venom while Polyrhachis use higher rates of grooming. The results show how alternative investment strategies can evolve for disease defence, notably the highly effective application of acidic venom by O. smaragdina, and highlight the need for targeted comparative studies to understand how organisms respond to the ubiquitous threat from parasites.

Location and external characteristics of the Oecophylla smaragdina queen nest

The Asian weaver ant Oecophylla smaragdina is of importance to Southeast Asian livelihoods as a source of human food and animal feed and as biological control agent in tree crops including mango and citrus. The introduction of weaver ants in plantations requires the inclusion of the reproductive queen. We report on locating the gravid queen in a mature O. smaragdina colony in Laos. The queen tree could be identified by considering tree height and number of nests in the tree: no tree was taller and housed more nests than the queen tree. The queen nest was a small nest, located near the tree top and near the trunk, and with more workers patrolling its exterior than at other small nests in the queen tree. The queen nest can be highly inconspicuous in dense tree crowns. Queen nest identification was ascertained by tapping and shaking nests, supporting branches, or entire trees, which elicits queen evacuation with retinue.