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Efforts to inhibit the growth of oral Burkitt's lymphoma cells require an effective strategy, one of that uses Papua's ant nest plant (Myrmecodia pendens) which are natural medicinal plants. In the present study, induction of cell cycle arrest and apoptosis of an oral Burkitt's lymphoma cell (Raji cell)-mediated by an ethyl acetate fraction of Papua's ant nest plant through down regulation of cyclin E-CDK2 complex was examined. For detection of cell cycle arrest was evaluated by flow-cytometer. Induction of apoptosis was detected by colorimetric assay caspase-3, -8 and -9. The level of cyclin E and CDK2 was carried out by Elisa kit. The results revealed the active fraction of the ant nest was markedly induced the cell cycle arrest in the G0-G1 phase according to increased concentration followed bythe induction of apoptosis characterized by elevated of proteolytic activity of caspase-3, -8 and -9. Cyclin E and CDK2 level was significantly decreased in cell treated with ant nest fraction. These results suggest the ethyl acetate fraction of the ant nest plant had a strong potential antitumor activity of oral malignant Burkitt's lymphoma cell proofed by the induction of cell cycle arrest and apoptosis through down regulation of cyclin E-CDK2 complex. [ABSTRACT FROM AUTHOR]

B Cover Legend b Computed tomography-based 3D model of an ant domatia from the Fijian epiphyte I Squamellaria wilsonii i . Courtesy of Guillaume Chomicki (Chomicki & Renner, pp. 2011-2023). Read more about our covers in the "Behind the cover" blog: newphytologist.org/behind-the-cover. [Extracted from the article]

This study aims to know how the inhibitory power of angiogenesis interleukin 8 ethanol fraction of ant nest extract in Burkitt's lymphoma cancer cell culture. The study was conducted in a pure laboratory experimental method using Burkitt's lymphoma cancer cell cultures. Gradual research began with determination, extraction, fractionation, making DMEM medium, activation of Burkitt’s Lymphoma cancer cells, up to cytotoxicity test and angiogenesis inhibition test of flavonoid fraction extract of ant nests. Data were analyzed using twoway ANOVA followed by Post Hoc LSD (Least Significant Difference) test with a significance level of 95%. Cytotoxicity test results showed that the flavonoid ethyl acetate fraction at a concentration of 1000 μg / mL could cause cell death as much as 82.71%, and at the lowest concentration of 7.8125 μg / mL can cause cell death by 39.75% cells. The results of the angiogenesis inhibition test showed a significant change in the expression of interleukin 8 in standard solutions. Changes in the expression of interleukin 8 in ethanol solution and ethyl acetate solution with a concentration of 0 to a concentration of 125 results obtained continued to increase. However, when the ethanol solution with 250 levels, the results obtained decreased from 0.254 to 0.237. Likewise, changes in the expression of interleukin 8 in ethyl acetate solution with a concentration of 250 results obtained decreased from 0.291 to 0.261. [ABSTRACT FROM AUTHOR]

Background and Aims Even when adapted to flooding environments, the spatial distribution, growing strategies and anti-herbivore defences of plants face stressful conditions. Here we describe the effects of flooding on carbon allocation on growth, domatia and leaf production, and the herbivory on the myrmecophyte domatia-bearing Tococa coronata Benth. (Melastomataceae) growing along river banks in the Amazon region. Methods In an area of 80 000 m2of riparian forest along the Juruena River we actively searched for individuals of T. coronata. In each plant we evaluated the size of the plant when producing the first domatium and determined its best predictor: (1) plant total height; (2) size of plants above flood level; or (3) length of time each plant spent underwater. We also compared the herbivory, internode elongation, foliar asymmetry and specific leaf weight between T. coronata individuals growing above and below the maximum flooding level. The distance to the river and the height of the first domatium produced were compared between T. coronata and its sympatric congener, T. bulifera. Key Results We found that T. coronata invests in rapid growth in the early ontogenetic stages through an elongation of internodes rather than in constitutive anti-herbivore defences to leaves or domatia to exceed the maximum flooding level. Consequently, its leaf herbivory was higher when compared with those produced above the flooding level. Individuals with leaves above flood levels produce coriaceous leaves and ant-domatias. Thus, flooding seems to trigger changes in growth strategies of the species. Furthermore, T. coronata occurs within the flood level, whereas its congener T. bullifera invariably occurs at sites unreachable by floods. Conclusion Even in conditions of high stress, T. coronata presents both physiological and adaptive strategies that allow for colonization and establishment within flooded regions. These mechanisms involve an extreme trade-off of postponing adult plant characteristics to rapid growth to escape flooding while minimizing carbon allocation to defence. [ABSTRACT FROM AUTHOR]

1. Ant–plant mutualisms are among the most widespread and ecologically important insect–plant interactions in the tropics. The multitrophic mutualism involving Macaranga plants (Euphorbiaceae) and Crematogaster ants (Formicidae) is the most diverse in Southeast Asia. This interaction also includes trophobiotic scale insects (Coccidae) and nematodes inhabiting ant refuse piles. 2. Here two myrmecophytic systems were compared, Macaranga trachyphylla with Crematogaster captiosa (Mt + Cc) and Macaranga beccariana with Crematogaster decamera (Mb + Cd), using a fine‐scale dissection of the stems. For the two plant species, for each internode, both contents (ants, coccids, refuse piles) and structure (internode height, numbers of open and occluded ant holes) were recorded. 3. There were significant patterns in the vertical distribution of ant colonies and their symbionts in the plant stems. Most coccids were kept in the highest sections of both systems, although Mb + Cd hosted a broader range of coccid species than Mt + Cc. Three nematode species were recorded, but with a rather low specificity to plant or ant species. Furthermore, the fine‐scale distribution showed aggregation of closed holes with ant brood and separation of nematode‐infested refuse piles from eggs. 4. The results of this study indicate that ants manipulate spatial colony structure via distribution of brood, holes and the symbionts. It is suggested that ants optimise the location of refuse piles and occluded holes via spatial heterogeneity in their distribution among internodes. This paper discusses the protective role of occluded holes and demonstrates some general interactions with other symbiotic fauna. [ABSTRACT FROM AUTHOR]

Direct and indirect negative interactions between ant guards and pollinators on ant-plants are expected for two reasons. First, aggressive ants may deter pollinators directly. Second, pollinators benefit from plant investment in reproduction whilst ants benefit from plant investment in indirect defense, and resource allocation trade-offs between these functions could lead to indirect conflict. We explored the potential for ant-pollinator conflict in a Mexican myrmecophile, Turnera velutina, which rewards ants with extrafloral nectar and pollinators with floral nectar. We characterized the daily timing of ant and pollinator activity on the plant and used experiments to test for direct and indirect conflict between these two groups of mutualists. We tested for direct conflict by quantifying pollinator responses to flowers containing dead specimens of aggressive ant species, relative to unoccupied control flowers. We assessed indirect conflict by testing for the existence of a trade-off in sugar allocation between ant and pollinator rewards, evidenced by an increase in floral nectar secretion when extrafloral nectar secretion was prevented. Secretion of floral and extrafloral nectar, activity of ants and pollinators, and pollen deposition all overlapped in daily time and peaked within the first 2 h after flowers opened. We found evidence of direct conflict, in that presence of ants inside the flowers altered pollinator behavior and reduced visit duration, although visit frequency was unchanged. We found no evidence for indirect conflict, with no significant difference in the volume or sugar content of floral nectar between control plants and those in which extrafloral nectar secretion was prevented. The presence of ants in flowers alters pollinator behavior in ways that are likely to affect pollination dynamics, though there is no apparent tradeoff between plant investment in nectar rewards for pollinators and ant guards. Further studies are required to quantify the effect of the natural abundance of ants in flowers on pollinator behavior, and any associated impacts on plant reproductive success. [ABSTRACT FROM AUTHOR]

Myrmecodia, or ant nest plant, is an indigenous medicinal plant traditionally used by local people in West Papua to treat a variety of hereditary diseases. It has been empirically proven to have a positive effect in treating various types of cancer, diabetes, heart problems, hypertension, lung, stroke, etc. High performance thin layer chromatographic (HPTLC) methods were developed and validated in order to compare antioxidant activity and to evaluate the contribution of selected phenolic compounds and stigmasterol to total antioxidant capacity in different extracts from Myrmecodia platytyrea . As expected, total phenolic content is highly correlated with antioxidant activity ( R = 0.86). The ethyl acetate extract had the highest reducing antioxidant activity, followed by ethanol, methanol and dichloromethane. The phenolic content of extracts was observed to increase in the following order: methanol > ethyl acetate > ethanol > dichloromethane. Although, the highest solubility of sterols observed in the ethyl acetate extract, might contribute to the highest antioxidant activity observed in this extract, there was no significant antioxidant activity of stigmasterol observed. While polyphenolic content is highly correlated to gallic acid concentration, free radical scavenging activity is related to caffeic acid. Strong positive and significant correlations between total phenolic content and radical scavenging activity, suggests that phenolic compounds are the main contributors to antioxidant activity in the sample extracts. Although the ethyl acetate extract has significant antioxidant activity, its' antioxidant activity was found not to be related to the plant sterols present in the extract. [ABSTRACT FROM AUTHOR]

Ascomycete fungi in the nests of ants inhabiting plants (= myrmecophytes) are very often cultivated by the ants in small patches and used as food source. Where these fungi come from is not known yet. Two scenarios of fungus recruitment are possible: (1) random infection through spores or hyphal fragments from the environment, or (2) transmission from mother to daughter colonies by the foundress queen. It is also not known at which stage of the colony life cycle fungiculture is initiated, and whether the- symbiont fungi serve as food for the ant queen. To clarify these questions, we investigated four Azteca ant species inhabiting three different Cecropia species (C. insignis, C. obtusifolia, and C. peltata). We analysed an rRNA gene fragment from 52 fungal patches produced by founding queens and compared them with those from established Azteca colonies (n = 54). The infrabuccal pockets of winged queens were dissected to investigate whether young queens carry fungi from their mother colony. Additionally, 15N labelling experiments were done to verify whether the queen feeds on the patches until she is nourished by her first worker offspring. We infer from the results that the fungi cultivated in hollow plant structures are transferred from the parental colony of the young queen. First, fungal genotypes/OTU diversity was not significantly different between foundress queen patches and established colonies, and second, hyphal parts were discovered in the infrabuccal pockets of female alates. We could show that fungiculture already starts before queens lay their eggs, and that the queens do not feed on fungal patch material but feed it to the larvae. Our findings suggest that fungiculture may be crucial for successful colony founding of arboreal ants in the tropics. [ABSTRACT FROM AUTHOR]

Abstract: While foundation species can stabilize ecosystems at landscape scales, their ability to persist is often underlain by keystone interactions occurring at smaller scales. Acacia drepanolobium is a foundation tree, comprising >95% of woody cover in East African black‐cotton savanna ecosystems. Its dominance is underlain by a keystone mutualistic interaction with several symbiotic ant species in which it provides housing (swollen thorns) and carbohydrate‐rich nectar from extra‐floral nectaries (EFN). In return, it gains protection from catastrophic damage from mega‐herbivores. Crematogaster mimosae is the ecologically dominant symbiotic ant in this system, also providing the highest protection services. In addition to tending EFN, C. mimosae tend scale insects for carbohydrate‐rich honeydew. We investigated the role of scale insects in this specialized ant‐plant interaction. Specifically, does this putatively redundant third partner strengthen the ant‐plant mutualism by making the ant a better protector of the tree? Or does it weaken the mutualism by being costly to the tree while providing no additional benefit to the ant‐plant mutualism? We coupled observational surveys with two scale‐manipulation experiments and found evidence that this third partner strengthens the ant‐plant mutualism. Trees with scale insects experimentally removed experienced a 2.5X increase in elephant damage compared to trees with scale insects present over 10 months. Reduced protection was driven by scale removal causing a decrease in ant colony size and per capita baseline activity and defensive behavior. We also found that ants increased scale‐tending and the density of scale insects on trees when EFN were experimentally reduced. Thus, in this system, scale insects and EFN are likely complementary, rather than redundant, resources with scale insects benefitting ants when EFN production is low (such as during annual dry periods in this semi‐arid ecosystem). This study reveals that a third‐partner strengthens an ant‐plant mutualism that serves to stabilize a whole ecosystem. [ABSTRACT FROM AUTHOR]

Establishing a horizontally transmitted mutualism is a critical step for many organisms, particularly when an individual can engage with only one partner over its lifetime. Ant foundresses shed their wings before they start to lay eggs, which makes host choice particularly critical for plant-ants that exclusively colonize myrmecophytes., Volatile organic compounds (VOCs) can indicate the identity and physiological condition of an individual and frequently serve as signals or cues that facilitate partner choice. Thus, we hypothesized that obligate plant-ants use VOCs to determine the quality of potential host plants., Indeed, winged females of the plant-ant, Pseudomyrmex ferrugineus, used plant odours to identify high-quality acacia hosts among different species and among individuals of the same species. The VOC blend of a branch was related to reward production and, interestingly, the least attractive blend contained the highest number of compounds., Although only seven different VOCs could be detected in the blend of the high-reward host species, the low-reward host emitted 13 different compounds, among which (S)-(-)-limonene and β-linalool were the dominant ones. Complementing the odour of the high-reward host with (S)-(-)-limonene, β-linalool or α-terpinene reduced its attractiveness. Strikingly, these compounds inhibited bacterial pathogens of the host plant., Synthesis. Plant-ants can use host plant odours that contain resistance-related VOCs to judge on host quality, likely because of negative crosstalk between direct resistance to disease and investment in ant-mediated defence. VOCs can serve as cues that provide reliable information for partner choice, particularly when their emission results from a physiological process that causally relates to the quality of an individual as a mutualist. [ABSTRACT FROM AUTHOR]

We examined the morphology of the cauline domatia of the semi-myrmecophyte Humboldtia brunonis at different stages of ontogeny. We observed that the hollow chamber in H. brunonis is spontaneously formed by the plant, and suggest this to be a collective effect of both schizogeny and lysogeny, following acropetal lignification of the pith cells as the domatium internode swells up. Unlike some other cauline domatia, there is a self-opening slit that provides access to the domatium chamber. We investigated the micro-structure of the inner wall of the domatia using scanning electron microscopy, and observed that cells that form the inner lining of the domatia cavity have canaliculated, lignified sclerenchyma with numerous plasmodesmata, as reported for the true myrmecophyte Leonardoxa africana , which could explain the observed nutrient flux from domatia-dwelling invertebrates into the host plant. We also observed fungal mycelia in ant-occupied domatia, though the role of fungi in this ant–plant system awaits further investigation. [ABSTRACT FROM AUTHOR]

1. Understanding the degree to which populations and communities are limited by both bottom-up and top-down effects is still a major challenge for ecologists, and manipulation of plant quality, for example, can alter herbivory rates in plants. In addition, biotic defence by ants can directly influence the populations of herbivores, as demonstrated by increased rates of herbivory or increased herbivore density after ant exclusion. The aim of this study was to evaluate bottom-up and top-down effects on herbivory rates in a mutualistic ant-plant. 2. In this study, the role of Azteca alfari ants as biotic defence in individuals of Cecropia pachystachya was investigated experimentally with a simultaneous manipulation of both bottom-up (fertilisation) and top-down (ant exclusion) factors. Four treatments were used in a fully factorial design, with 15 replicates for each treatment: (i) control plants, without manipulation; (ii) fertilised plants, ants not manipulated; (iii) unfertilised plants and excluded ants and (iv) fertilised plants and ants excluded. 3. Fertilisation increased the availability of foliar nitrogen in C. pachystachya, and herbivory rates by chewing insects were significantly higher in fertilised plants with ants excluded. 4. Herbivory, however, was more influenced by bottom-up effects - such as the quality of the host plant - than by top-down effects caused by ants as biotic defences, reinforcing the crucial role of leaf nutritional quality for herbivory levels experienced by plants. Conditionality in ant defence under increased nutritional quality of leaves through fertilisation might explain increased levels of herbivory in plants with higher leaf nitrogen. [ABSTRACT FROM AUTHOR]

Myrmecophyte is a common medicinal plant used by local people in Indonesia for treating various diseases especially in Papua. Bengkulu province is one of the Myrmecophyte habitats, but there has no report on its identity and distribution. The objectives of this research were to identify the diversity and analyze the Myrmecophytes distribution as well as factor affecting its presence. This study used purposive sampling method by exploring the area where Myrmecophytes commonly found. The Myrmecophyte distribution based on host tree was analyzed using Morishita index and the autecological analysis of abiotic factors was performed using Principal Component Analysis (PCA) generated from Minitab 16. The results of this research showed that there were two species of Myrmecophytes in Bengkulu province, namely Hydnophytum formicarum and Myrmecodia tuberosa, as well as two variants of M. tuberosa i.e. M. tuberosa 'armata' and M. tuberosa 'siberutensis'. The distribution of Myrmecophytes based on host tree was mostly randomly scattered in Central Bengkulu regency, Seluma, North Bengkulu, South Bengkulu and Kaur. Their distributions were affected by light intensity and temperature. The data of this research can be used as basic information for carried out conservation efforts in Bengkulu province. The abundance of Myrmecophytes is also used as a source of additional income for local people in Bengkulu province. [ABSTRACT FROM AUTHOR]

A new myrmecophytic species, Neonauclea viridiflora, is described from Eastern Samar, Philippines. It bears similarity to N. formicaria, but is easily distinguished by having obovate leaves, smaller flowering heads of 30-35 mm, persistent calyces that are glabrous inside the tube, calyx shafts that are connate at the bases for 0.8-2.5mmor sometimes entirely connate with the adjacent lobe, apical portions of the calyces that are bluntly turbinate but globose to clavate when dry, calyx summits that are bluntly conical but the apex is somewhat flattened when dry, and smaller and slender light green corollas. Comparative illustrations of the calyx lobes, a key to the Philippine myrmecophytic Neonauclea species, and a map for these species' distributions in the Philippines are provided in the study. [ABSTRACT FROM AUTHOR]

Extrafloral nectar ( EFN) mediates food-for-protection mutualisms between plants and ants. Such mutualisms exist within a complex web of biotic interactions, and in a framework provided by the abiotic environment. Both biotic and abiotic factors, therefore, affect the outcome of ant-plant interactions. We conducted an experiment to determine the effects of ant activity, and light intensity, on herbivory rates, growth, and reproductive fitness in Senna mexicana var. chapmanii, a perennial legume native to pine rockland habitats of south Florida. Forty plants were divided among four treatments in a factorial experimental design with two independent variables: ant activity and light intensity. Plants were divided equally between sunny and shady habitats, and ants were excluded from half of the plants in each habitat type. The presence of ants significantly reduced herbivory rates in S. chapmanii. In shaded habitats, the presence of ants had no effect on plant reproductive fitness, however, in sunny habitats plants with ants produced significantly more seeds over the duration of the 1-yr study. Ants represent an important biotic defense against herbivores in S. chapmanii; however, their effects on plant fitness are dependent on light conditions. Pine rockland habitats in south Florida have been widely destroyed or mismanaged. In fragments that remain, suppression of fire has led to increased canopy closure and shading of the understory. These changes will likely negatively impact plants that rely on ants for defense. We highlight the importance of conservation efforts to preserve the pine rocklands and the fire regimes on which they rely. [ABSTRACT FROM AUTHOR]

Comparative studies of the population genetics of closely associated species are necessary to properly understand the evolution of these relationships because gene flow between populations affects the partners' evolutionary potential at the local scale. As a consequence (at least for antagonistic interactions), asymmetries in the strength of the genetic structures of the partner populations can result in one partner having a co-evolutionary advantage. Here, we assess the population genetic structure of partners engaged in a species-specific and obligatory mutualism: the Neotropical ant-plant, Hirtella physophora, and its ant associate, Allomerus decemarticulatus. Although the ant cannot complete its life cycle elsewhere than on H. physophora and the plant cannot live for long without the protection provided by A. decemarticulatus, these species also have antagonistic interactions: the ants have been shown to benefit from castrating their host plant and the plant is able to retaliate against too virulent ant colonies. We found similar short dispersal distances for both partners, resulting in the local transmission of the association and, thus, inbred populations in which too virulent castrating ants face the risk of local extinction due to the absence of H. physophora offspring. On the other hand, we show that the plant populations probably experienced greater gene flow than did the ant populations, thus enhancing the evolutionary potential of the plants. We conclude that such levels of spatial structure in the partners' populations can increase the stability of the mutualistic relationship. Indeed, the local transmission of the association enables partial alignments of the partners' interests, and population connectivity allows the plant retaliation mechanisms to be locally adapted to the castration behaviour of their symbionts. [ABSTRACT FROM AUTHOR]

Macaranga is a tree genus that includes many species of myrmecophytes, which are plants that harbor ant colonies within hollow structures known as domatia. The symbiotic ants (plant-ants) protect their host plants against herbivores; this defense mechanism is called 'ant defense'. A Bornean phasmid species Orthomeria cuprinus feeds on two myrmecophytic Macaranga species, Macaranga beccariana and Macaranga hypoleuca, which are obligately associated with Crematogaster ant species. The phasmids elude the ant defense using specialized behavior. However, the mechanisms used by the phasmid to overcome ant defenses have been insufficiently elucidated. We hypothesized that O. cuprinus only feeds on individual plants with weakened ant defenses. To test the hypothesis, we compared the ant defense intensity in phasmid-infested and non-infested M. beccariana trees. The number of plant-ants on the plant surface, the ratio of plant-ant biomass to tree biomass, and the aggressiveness of plant-ants towards experimentally introduced herbivores were significantly lower on the phasmid-infested trees than on the non-infested trees. The phasmid nymphs experimentally introduced into non-infested trees, compared with those experimentally introduced into phasmid-infested trees, were more active on the plant surface, avoiding the plant-ants. These results support the hypothesis and suggest that ant defenses on non-infested trees effectively prevent the phasmids from remaining on the plants. Thus, we suggest that O. cuprinus feeds only on the individual M. beccariana trees having decreased ant defenses, although the factors that reduce the intensity of the ant defenses remain unclear. [ABSTRACT FROM AUTHOR]

Aim We ask empirically how the strength of the three major interactions - predation, competition and mutualism - changes with increasing island area. We review and expand current theory concerning these relationships. Location Data for evaluating this question come from several Bahamian archipelagos and involve both experiments and observations. The latter can be especially long term; in one case data were collected over a 17-year period. Methods We analyse the effect size of the following interactions across a range of island areas: (1) predation by lizards on spiders, (2) competition between two lizard species, (3) competition between two spider species, (4) ant-plant mutualism, and (5) plant-pollinator mutualism. Results Effect sizes for predation and competition mostly show a hump-shaped relationship with island area. Effect sizes for ant-plant mutualism were reduced on large islands compared with smaller islands. Germination rate showed a steady increase with island area which we infer to be caused by an increase in pollinator limitation on smaller islands. Main conclusions We argue that the effect size-area relation has rather similar aetiologies for predation, competition and to a somewhat lesser extent ant-plant mutualism. Specifically, we suggest that high species diversity, top predators, plant defences and (for predation and competition) spatial heterogeneity with respect to refuges or resource use reduce effect size on large islands, while harsh abiotic conditions, marine subsidies and stochastic events reduce effect size on small islands. Thus, for these interaction types, the greatest effect sizes are observed on intermediate-sized islands. For plant-pollinator mutualism we suggest that the monotonic increase in effect size with increasing island area is the result of interaction strength being enhanced, rather than weakened, by diversity. [ABSTRACT FROM AUTHOR]

A tropical small tree, Callicarpa saccata, is known to have a symbiotic relationship with ants. It has sac-like structures at the base of the leaves that are inhabited by ants. No other species has been determined to be a myrmecophyte among the ca. 140 species of this genus. However, our recent field investigation discovered that two other species on Borneo ( C. barbata and C. teneriflora) have hollow stems, which seem to be inhabited by ants. We observed the morphological features of these species in relation to their usage by ants, and became convinced that they are mymecophytic species. The molecular phylogenetic analyses using ITS and chloroplast regions suggest that C. saccata and C. teneriflora are closely related, but the differences in the myrmecophytic features of these species should be noted. [ABSTRACT FROM AUTHOR]

Members of the Euphorbiaceae are ecologically important elements of Southeast Asian forests. Species of the pioneer tree genus Macaranga, which is also known for its association with ants, are often abundant in disturbed areas. Phylogenetic studies suggested a recent radiation of section Pachystemon which comprises the majority of obligate myrmecophytes within Macaranga. In the present study, we analyzed the genetic structure of three closely related species of this section ( M. constricta, M. griffithiana, and M. motleyana) with the aim of resolving their controversial taxonomy and historical biogeography. Chloroplast DNA haplotypes proved to be species-specific and showed a strong phylogeographic pattern. Nuclear microsatellite data supported the taxonomic distinctness of M. griffithiana and M. motleyana, but gave ambiguous results for M. constricta. Genetic differentiation was stronger each within M. griffithiana and M. motleyana than between M. constricta and M. griffithiana, highlighting problems of defining species boundaries. We found no indication for introgression or hybridization events. The high intraspecific morphological variation of the Bornean endemic M. motleyana was partly reflected by similar patterns of genetic variation. The pronounced genetic structure indicates a comparatively long diversification for this species. In contrast, the weak genetic differentiation within M. griffithiana, as well as the widespread distribution of its most common chloroplast haplotype from peninsular Malaysia up to Indochina, indicates a recent expansion in this area. Despite their morphological similarity and close relatedness, all species possess their own specific ant-partners with a corresponding distribution pattern. [ABSTRACT FROM AUTHOR]

Myrmecophyte plants house ants within domatia in exchange for protection against herbivores. Ant-myrmecophyte mutualisms exhibit two general patterns due to competition between ants for plant occupancy: (i) domatia nest sites are a limiting resource and (ii) each individual plant hosts one ant species at a time. However, individual camelthorn trees (Vachellia erioloba) typically host two to four ant species simultaneously, often coexisting in adjacent domatia on the same branch. Such fine-grain spatial coexistence brings into question the conventional wisdomon ant-myrmecophytemutualisms. Camelthorn ants appear not to be nest-site limited, despite low abundance of suitable domatia, and have random distributions of nest sites within and across trees. These patterns suggest a lack of competition between ants for domatia and contrast strongly with other antmyrmecophyte systems. Comparison of this unusual case with others suggests that spatial scale is crucial to coexistence or competitive exclusion involving multiple ant species. Furthermore, coexistence may be facilitated when co-occurring ant species diverge strongly on at least one niche axis. Our conclusions provide recommendations for future ant-myrmecophyte research, particularly in utilizing multi-species systems to further our understanding of mutualism biology. [ABSTRACT FROM AUTHOR]

1. Ants establish mutualistic interactions involving a wide range of protective relationships (myrmecophily), in which they provide defence against enemies and partners provide food rewards and/or refuge. Although similar in the general outcome, myrmecophilic interactions differ in some characteristics such as quantity and quality of rewards offered by partners which may lead to different specialisation levels and, consequently, to different network properties. 2. The aim of this study was to identify structural patterns in myrmecophilic interaction networks, focusing on aspects related to specialisation: network modularity, nestedness and taxonomic relatedness of interaction ranges. To achieve this, a database of networks was compiled, including the following interactions: ants and domatia-bearing plants (myrmecophytes); ants and extrafloral nectary-bearing plants ( EFNs); ants and floral nectary-bearing plants ( FNs); ants and Lepidoptera caterpillars; and ants and Hemiptera. 3. Myrmecophilic networks differed in their topology, with ant-myrmecophyte and ant- Lepidoptera networks being similar in their structural properties. A continuum was found, ranging from highly modular networks and phylogenetically structured interaction ranges in ant-myrmecophyte followed by ant- Lepidoptera networks to low modularity and taxonomically unrelated interaction ranges in ant- Hemiptera, EFN and FN networks. 4. These results suggest that different network topologies may be found across communities of species with similar interaction types, but also, that similar network topologies can be achieved through different mechanisms such as those between ants and myrmecophytes or Lepidoptera larvae. This study contributes to a generalisation of myrmecophilic network patterns and a better understanding of the relationship between specialisation and network topology. [ABSTRACT FROM AUTHOR]

Many ant-plants have pubescent leaves, but the extent to which leaf trichomes enhance the defensive capabilities of ant-plants is poorly known. Here, we examined the influence of foliar trichomes and ants on herbivory in the Neotropical ant-plant Tococa guianensis. We performed a feeding preference test and a field experiment in which we manipulated the presence of ants and trichomes in three distinct populations of T. guianensis; two associated with obligate mutualistic ants and one associated with opportunistic ants. We found that both mutualistic ants and leaf trichomes act as mechanisms of defense against herbivores in T. guianensis. However, the relative importance of each of these two mechanisms was context dependent. The magnitude of the effect of trichomes (as measured by the effect size) was relatively low and varied little among plant populations. The effect of ants on foliar herbivory was up to seven times stronger than the effect of the trichomes. Nevertheless, because the magnitude of ant effects was spatially variable-depending on whether mutualistic ants were present or not, and probably also on the local abundance of herbivores-the relative contribution of ants and trichomes for plant defense was also spatially variable. These findings indicate that mechanical defenses (leaf trichomes) alone cannot replace the biotic defenses of T. guianensis. However, trichomes can play a comparatively more important role in plant defense at times or places where mutualistic ants are not present. [ABSTRACT FROM AUTHOR]

Ant-plant symbioses involve over 110 ant species in five subfamilies that are facultative or obligate occupants of stem, leaf or root domatia formed by hundreds of ant-plant species. The phylogenetic distribution and geological ages of these associations, and the frequency of gains or losses of domatium, are largely unknown., We compiled an up-to-date list of ant domatium-bearing plants, estimated their probable true number from model-based statistical inference, generated dated phylogenies that include c. 50% of ant-plant lineages, and traced the occurrence of domatia and extrafloral nectaries on a 1181-species tree, using likelihood and Bayesian methods., We found 681 vascular plants with domatia (159 genera in 50 families) resulting from minimally 158 inferred domatium origins and 43 secondary losses over the last 19 Myr. The oldest African ant-plant symbioses are younger than those in Australasia and the Neotropics. The best statistical model suggests that the true number of myrmecophytes may approach 1140 species., The phylogenetic distribution of ant-plants shows that domatia evolved from a range of pre-adapted morphological structures and have been lost frequently, suggesting that domatia have no generalizable effect on diversification. The Miocene origin of ant-plant symbioses is consistent with inferred changes in diet and behaviour during ant evolution. [ABSTRACT FROM AUTHOR]

Macaranga myrmecophytes (ant-plants) are generally well protected from herbivore attacks by their symbiotic ants (plant-ants). However, larvae of Arhopala (Lepidoptera: Lycaenidae) species survive and develop on specific Macaranga ant-plant species without being attacked by the plant-ants of their host species. We hypothesized that Arhopala larvae chemically mimic or camouflage themselves with the ants on their host plant so that the larvae are accepted by the plant-ant species of their host. Chemical analyses of cuticular hydrocarbons showed that chemical congruency varied among Arhopala species; A. dajagaka matched well the host plant-ants, A. amphimuta did not match, and unexpectedly, A. zylda lacked hydrocarbons. Behaviorally, the larvae and dummies coated with cuticular chemicals of A. dajagaka were well attended by the plant-ants, especially by those of the host. A. amphimuta was often attacked by all plant-ants except for the host plant-ants toward the larvae, and those of A. zylda were ignored by all plant-ants. Our results suggested that conspicuous variations exist in the chemical strategies used by the myrmecophilous butterflies that allow them to avoid ant attack and be accepted by the plant-ant colonies. [ABSTRACT FROM AUTHOR]

Plants simultaneously maintain mutualistic relationships with different partners that are connected through the same host, but do not interact directly. One or more participating mutualists may alter their host's phenotype, resulting in a shift in the host's ecological interactions with all other mutualists involved. Understanding the functional interplay of mutualists associated with the same host remains an important challenge in biology. Here, we show belowground nitrogen-fixing rhizobia on lima bean (Phaseolus lunatus) alter their host plant's defensive mutualism with aboveground ants. We induced extrafloral nectar (EFN), an indirect defense acting through ant attraction. We also measured various nutritive and defensive plant traits, biomass, and counted ants on rhizobial and rhizobia-free plants. Rhizobia increased plant protein as well as cyanogenesis, a direct chemical defense against herbivores, but decreased EFN. Ants were significantly more attracted to rhizobia-free plants, and our structural equation model shows a strong link between rhizobia and reduced EFN as well as between EFN and ants: the sole path to ant recruitment. The rhizobia-mediated effects on simultaneously expressed defensive plant traits indicate rhizobia can have significant bottom-up effects on higher trophic levels. Our results show belowground symbionts play a critical and underestimated role in determining aboveground mutualistic interactions. [ABSTRACT FROM AUTHOR]

A previously reported mitochondrial DNA (mtDNA) phylogeny of Crematogaster (subgenus Decacrema) ants inhabiting Macaranga myrmecophytes indicated that the partners diversified synchronously and their specific association has been maintained for 20 million years. However, the mtDNA clades did not exactly match morphological species, probably owing to introgressive hybridization among younger species. In this study, we determined the congruence between nuclear simple sequence repeat (SSR, also called microsatellite) genotyping and mtDNA phylogeny to confirm the suitability of the mtDNA phylogeny for inferring the evolutionary history of Decacrema ants. Analyses of ant samples from Lambir Hills National park, northeastern Borneo, showed overall congruence between the SSR and mtDNA groupings, indicating that mtDNA markers are useful for delimiting species, at least at the local level. We also found overall high host-plant specificity of the SSR genotypes of Decacrema ants, consistent with the specificity based on the mtDNA phylogeny. Further, we detected cryptic genetic assemblages exhibiting high specificity toward particular plant species within a single mtDNA clade. This finding, which may be evidence for rapid ecological and genetic differentiation following a host shift, is a new insight into the previously suggested long-term codiversification of Decacrema ants and Macaranga plants. [ABSTRACT FROM AUTHOR]

Myrmecophytes depend on symbiotic ants (plant-ants) to defend against herbivores. Although these defensive mechanisms are highly effective, some herbivorous insects can use myrmecophytes as their host-plants. The feeding habits of these phytophages on myrmecophytes and the impacts of the plant-ants on their feeding behavior have been poorly studied. We examined two phasmid species, Orthomeria alexis and O. cuprinus, which are known to feed on Macaranga ( Euphorbiaceae) myrmecophytes in a Bornean primary forest. Our observations revealed that: (i) each phasmid species relied on two closely-related myrmecophytic Macaranga species for its host-plants in spite of their normal plant-ant symbioses; and (ii) there was little overlap between their host-plant preferences. More O. cuprinus adults and nymphs were found on new leaves, which were attended by more plant-ants than mature leaves, while most adults and nymphs of O. alexis tended to avoid new leaves. In a feeding choice experiment under ant-excluded conditions, O. alexis adults chose a non-host Macaranga myrmecophyte that was more intensively defended by plant-ants and was more palatable than their usual host-plants almost as frequently as their usual host-plant, suggesting that the host-plant range of O. alexis was restricted by the presence of plant-ants on non-host-plants. Phasmid behavior that appeared to minimize plant-ant attacks is described. [ABSTRACT FROM AUTHOR]

Mutualisms play a central role in the origin and maintenance of biodiversity. Because many mutualisms have strong demographic effects, interspecific variation in partner quality could have important consequences for population dynamics. Nevertheless, few studies have quantified how a mutualist partner influences population growth rates, and still fewer have compared the demographic impacts of multiple partner species. We used integral projection models parameterized with three years of census data to compare the demographic effects of two ant species, Crematogaster laevis and Pheidole minutula, on populations of the Amazonian ant plant Maieta guianensis. Estimated population growth rates were positive (i.e., λ > 1) for all ant-plant combinations. However, populations with only Pheidole minutula had the highest asymptotic growth rate (λ = 1.23), followed by those colonized by Crematogaster laevis (λ = 1.16), and in which the partner ant alternated between C. laevis and P. minutula at least once during our study (λ = 1.15). Our results indicate that the short-term superiority of a mutualist partner (in this system, P. minutula is a better defender of plants against herbivores than C. laevis) can have long-term demographic consequences. Furthermore, the demographic effects of switching among alternative partners appear to be context dependent, with no benefits to plants hosting C. laevis but a major cost of switching to plants hosting P. minutula. Our results underscore the importance of expanding the study of mutualisms beyond the study of pair-wise interactions to consider the demographic costs and benefits of interacting with different, and multiple, potential partners. [ABSTRACT FROM AUTHOR]

New associations have recently been discovered between arboreal ants that live on myrmecophytic plants, and different groups of fungi. Most of the – usually undescribed – fungi cultured by the ants belong to the order Chaetothyriales (Ascomycetes). Chaetothyriales occur in the nesting spaces provided by the host plant, and form a major part of the cardboard-like material produced by the ants for constructing nests and runway galleries. Until now, the fungi have been considered specific to each ant species. We focus on the three-way association between the plant Tetrathylacium macrophyllum (Salicaceae), the ant Azteca brevis (Formicidae: Dolichoderinae) and various chaetothyrialean fungi. Azteca brevis builds extensive runway galleries along branches of T. macrophyllum. The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae. In order to characterise the specificity of the ant–fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences. This gave 128 different fungal genotypes, 78% of which were clustered into three monophyletic groups. The most common fungus (either genotype or approximate species-level OTU) was found in the runway galleries of 63% of the investigated ant colonies. This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Extrafloral nectar ( EFN) is a predictable and renewable resource for many ant colonies, and different ant species compete strongly to obtain and monopolize this highly nutritious food resource. Despite the importance of competition in structuring patterns of ant-plant interactions, this biological mechanism has been largely ignored in studies involving ant-plant networks. In this study we investigate the role of ant dominance hierarchy in structuring an ecological network involving ants and EFN-bearing plants in a tropical coastal environment in Mexico. We show that within a nested ant-plant network, ant species found in the central core of highly interacting species were competitively superior, showing massive recruitment and resource domination, compared with peripheral species with fewer interactions. Moreover, we also observed that both central and peripheral ant species have the ability to quickly find the food resource. However, after 2 h of observation, central ant species are more frequently collected on the food resource when compared with peripheral species. We hypothesize that the existence of a central core of competitive ant species may indicate that most plant species found within ant-plant networks could be better protected against herbivory by these dominant ant species. In short, our results highlight the importance of competition and monopolization in the resource use by ants in the maintenance of the nested pattern in ant-plant mutualistic networks. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 405-414. [ABSTRACT FROM AUTHOR]

How a symbiosis originates and is maintained are important evolutionary questions. Symbioses in myrmecophytes (plants providing nesting for ants) are believed to be maintained by protection and nutrients provided by specialist plant-ants in exchange for nesting spaces (called domatia) and nourishment offered by ant-plants. However, besides the benefits accrued from housing protective ants, the mechanisms contributing to the fitness advantages of bearing domatia have rarely been examined, especially because the domatia trait is usually constitutively expressed, and many myrmecophytes have obligate mutualisms with single ant species resulting in invariant conditions., In the unspecialized ant-plant Humboldtia brunonis (Fabaceae) that offers extrafloral nectar to ants, only some plants produce domatia in the form of hollow internodes. These domatia have a self-opening slit making them more prone to interlopers and are occupied mostly by non-protective ants and other invertebrates, especially arboreal earthworms. The protection mutualism with ants is restricted in geographical extent, occurring only at a few sites in the southernmost part of this plant's range in the Western Ghats of India., We examined nutrient flux from domatia residents to the plant using stable isotopes. We found that between 9% (earthworms) and 17% (protective or non-protective ants) of nitrogen of plant tissues nearest the domatium came from domatia inhabitants. Therefore, interlopers such as earthworms and non-protective ants contributed positively to the nitrogen budget of localized plant modules of this understorey tree. 15N-enriched feeding experiments with protective ants demonstrated that nutrients flowed from domatia inhabitants to nearby plant modules. Fruit set did not differ between paired hand-pollinated inflorescences on domatia and non-domatia bearing branches. This was possibly due to the nutrient flux from domatia to adjacent branches without domatia within localized modules., This study has demonstrated the nutritive role of non-protective ants and non-ant invertebrates, hitherto referred to as interlopers, in an unspecialized myrmecophyte. Our study suggests that even before the establishment of a specialized ant-plant protection mutualism, nutritional benefits conferred by domatia inhabitants can explain the fitness benefits of bearing domatia, and thus the maintenance of a trait that facilitates the establishment of a specialized ant-plant symbiosis. [ABSTRACT FROM AUTHOR]

We aimed to determine whether the nesting habits of ants have influenced their venom toxicity and composition. We focused on the genus Pseudomyrmex (Pseudomyrmecinae) comprising terrestrial and arboreal species, and, among the latter, plant-ants that are obligate inhabitants of myrmecophytes (i.e., plants sheltering ants in hollow structures). Contrary to our hypothesis, the venom of the ground-dwelling species, Pseudomyrmex termitarius , was as efficacious in paralyzing prey as the venoms of the arboreal and the plant-ant species, Pseudomyrmex penetrator and Pseudomyrmex gracilis . The lethal potency of P. termitarius venom was equipotent with that of P. gracilis whereas the venom of P. penetrator was less potent. The MALDI-TOF MS analysis of each HPLC fraction of the venoms showed that P. termitarius venom is composed of 87 linear peptides, while both P. gracilis and P. penetrator venoms (23 and 26 peptides, respectively) possess peptides with disulfide bonds. Furthermore, P. penetrator venom contains three hetero- and homodimeric peptides consisting of two short peptidic chains linked together by two interchain disulfide bonds. The large number of peptides in P. termitarius venom is likely related to the large diversity of potential prey plus the antibacterial peptides required for nesting in the ground. Whereas predation involves only the prey and predator, P. penetrator venom has evolved in an environment where trees, defoliating insects, browsing mammals and ants live in equilibrium, likely explaining the diversity of the peptide structures. [ABSTRACT FROM AUTHOR]

Obligate ant-plant interactions are known to be mutualistic but plant-ants that destroy flowers of their hosts have been reported. They were regarded as parasites in myrmecophytic systems. The mechanisms that lead to flower damage (sterilization) by plant-ants are not easy to understand as most sterilizing ants are actually regular colonizers of their plants and normally offer protection against herbivores and/or plant competition. It is difficult to find general patterns of ant or plant traits even in the few yet known associations of flower sterilization. We here present the first study from Southeast Asia where flower sterilizing occurs in the complex mutualistic Macaranga- Crematogaster system that differs from other cases. Flowers of M. hullettii in the Gombak Valley were destroyed by all three associated specific and otherwise protective Crematogaster species. The hypotheses that limitation of nesting space or food are main proximate factors for flower destruction were not strongly supported in our study system. Ants are even attracted to flowers by special food bodies produced by the plants. Only younger, not yet reproductive colonies were found to destroy flowers but not colonies with alates, indicating that flower sterilization behavior may only occur when the onset of host reproduction precedes ant reproduction, perhaps leading to a change in ant behavior. Fruit set always occurred in larger trees, and saplings for colonizing ant queens were therefore always present in the local population, stabilizing the association. [ABSTRACT FROM AUTHOR]

In protective ant-plant mutualisms, plants offer ants food (such as extrafloral nectar and/or food bodies) and ants protect plants from herbivores. However, ants often negatively affect plant reproduction by deterring pollinators. The aggressive protection that mutualistic ants provide to some myrmecophytes may enhance this negative effect in comparison to plant species that are facultatively protected by ants. Because little is known about the processes by which myrmecophytes are pollinated in the presence of ant guards, we examined ant interactions with herbivores and pollinators on plant reproductive organs. We examined eight myrmecophytic and three nonmyrmecophytic Macaranga species in Borneo. Most of the species studied are pollinated by thrips breeding in the inflorescences. Seven of eight myrmecophytic species produced food bodies on young inflorescences and/or immature fruits. Food body production was associated with increased ant abundance on inflorescences of the three species observed. The exclusion of ants from inflorescences of one species without food rewards resulted in increased herbivory damage. In contrast, ant exclusion had no effect on the number of pollinator thrips. The absence of thrips pollinator deterrence by ants may be due to the presence of protective bracteoles that limit ants, but not pollinators, from accessing flowers. This unique mechanism may account for simultaneous thrips pollination and ant defense of inflorescences. [ABSTRACT FROM AUTHOR]

Plant-animal interactions occur in a community context of dynamic and complex ecological interactive networks. The understanding of who interacts with whom is a basic information, but the outcomes of interactions among associates are fundamental to draw valid conclusions about the functional structure of the network. Ecological networks studies in general gave little importance to know the true outcomes of interactions and how they may change over time. We evaluate the dynamic of an interaction network between ants and plants with extrafloral nectaries, by verifying the temporal variation in structure and outcomes of mutualism for the plant community (leaf herbivory). To reach this goal, we used two tools: bipartite network analysis and experimental manipulation. The networks exhibited the same general pattern as other mutualistic networks: nestedness, asymmetry and low specialization and this pattern was maintained over time, but with internal changes (species degree, connectance and ant abundance). These changes influenced the protection effectiveness of plants by ants, which varied over time. Our study shows that interaction networks between ants and plants are dynamic over time, and that these alterations affect the outcomes of mutualisms. In addition, our study proposes that the set of single systems that shape ecological networks can be manipulated for a greater understanding of the entire system. [ABSTRACT FROM AUTHOR]

Despite the importance and increasing knowledge of ecological networks, sampling effort and intrapopulation variation has been widely overlooked. Using continuous daily sampling of ants visiting three plant species in the Brazilian Neotropical savanna, we evaluated for the first time the topological structure over 24 h and species-area relationships (based on the number of extrafloral nectaries available) in individual-based ant-plant networks. We observed that diurnal and nocturnal ant-plant networks exhibited the same pattern of interactions: a nested and non-modular pattern and an average level of network specialization. Despite the high similarity in the ants’ composition between the two collection periods, ant species found in the central core of highly interacting species totally changed between diurnal and nocturnal sampling for all plant species. In other words, this “night-turnover” suggests that the ecological dynamics of these ant-plant interactions can be temporally partitioned (day and night) at a small spatial scale. Thus, it is possible that in some cases processes shaping mutualistic networks formed by protective ants and plants may be underestimated by diurnal sampling alone. Moreover, we did not observe any effect of the number of extrafloral nectaries on ant richness and their foraging on such plants in any of the studied ant-plant networks. We hypothesize that competitively superior ants could monopolize individual plants and allow the coexistence of only a few other ant species, however, other alternative hypotheses are also discussed. Thus, sampling period and species-area relationship produces basic information that increases our confidence in how individual-based ant-plant networks are structured, and the need to consider nocturnal records in ant-plant network sampling design so as to decrease inappropriate inferences. [ABSTRACT FROM AUTHOR]

Abstract: Mutualistic interactions are embedded in networks of interactions that affect the benefits accruing to the mutualistic partners. Figs and their pollinating wasps are engaged in an obligate mutualism in which the fig is dependent on the fig pollinator for pollination services and the pollinator is dependent on fig ovules for brood sites. This mutualism is exploited by non-pollinating fig wasps that utilise the same ovules, but do not provide a pollination service. Most non-pollinating wasps oviposit from outside the inflorescence (syconium), where they are vulnerable to ant predation. Ficus schwarzii is exposed to high densities of non-pollinating wasps, but Philidris sp. ants patrolling the syconia prevent them from ovipositing. Philidris rarely catch wasps, but the fig encourages the patrolling by providing a reward through extra-floral nectaries on the surface of syconia. Moreover, the reward is apparently only produced during the phase when parasitoids are ovipositing. An ant-exclusion experiment demonstrated that, in the absence of ants, syconia were heavily attacked and many aborted as a consequence. Philidris was normally rare on the figs during the receptive phase or at the time of day when wasp offspring are emerging, so predation on pollinators was limited. However, Myrmicaria sp. ants, which only occurred on three trees, preyed substantially on pollinating as well as non-pollinating wasps. F. schwarzii occurs in small clusters of trees and has an exceptionally rapid crop turnover. These factors appear to promote high densities of non-pollinating wasps and, as a consequence, may have led to both a high incidence of ants on trees and increased selective pressure on fig traits that increase the payoffs of the fig–ant interaction for the fig. The fig receives no direct benefit from the reward it provides, but protects pollinating wasps that will disperse its pollen. [Copyright &y& Elsevier]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mutualisms are commonly threatened by parasites and cheaters: species that exploit the host-derived resources without providing an adequate service. Here, we summarize mechanisms for the stabilization of obligate defensive ant-plant mutualisms, a typical element of tropical lowland forests. Host plants exert partner choice and can sanction non-defending ants by shedding the domatia that serve as nesting space or ceasing the production of ant rewards. Hosts can also restrict the exploitation of the ant rewards by means of specific biochemical traits that decrease their quality for non-adapted generalist exploiters and, thus, convert them into exclusive rewards. Reward provisioning can even shift the competitive balance between mutualists and exploiters in favor of the mutualists. In turn, plant-ants show adaptations in their colony structure and changes in their digestive capacities that enhance their efficiency in the use of the host-derived resources. Founding queens use plant odors for host choice behavior, and ants not supplied with adequate amounts of EFN decrease their defensive service and thereby exert partner sanctions. Theoretical models and empirical research into mutualisms usually focus on actions that are taken by the host. Using ant-plants as model systems, we are now discovering the importance of contributions that come from the symbiont. This discovery indicates the potential for multiple reciprocal interactions between phenotypically plastic hosts and symbionts, which contribute significantly to what is still considered a miracle: the stability of mutualisms in the presence of exploiters. [ABSTRACT FROM AUTHOR]

Abstract: Plants frequently attract natural enemies of their herbivores, resulting in a reduction in tissue damage and often in enhanced plant fitness. While such indirect defenses can dramatically change as plants develop, only recently have ecologists begun to explore such changes and evaluate their role in mediating plant–herbivore–natural enemy interactions. Here we review the literature documenting ontogenetic patterns in plant rewards (i.e. extrafloral nectaries (EFNs), food bodies (FBs) and domatia) and volatile organic compounds (VOCs), and identify links between ontogenetic patterns in such traits and the attraction of natural enemies (ants). In the case of reward traits we concentrate in ant–plant studies, which are the most numerous. We report that all indirect defensive traits commonly vary with plant age but ontogenetic trajectories differ among them. Myrmecophytic species, which provide both food and shelter to their defenders, do not produce rewarding traits until a minimum size is reached. Then, a pronounced increase in the abundance of food rewards and domatia often occurs as plants develop, which explains the temporal succession or colony size increase of mutualistic ant species and, in some cases, leads to a reduction in herbivore damage and enhanced fitness as plants age. In contrast, ontogenetic patterns were less consistent in plant species that rely on VOC emissions to attract natural enemies or those that provide only food rewards (EFNs) but not nesting sites to their associated ants, showing an overall decline or lack of trend with plant development, respectively. Future research should focus on uncovering: (i) the costs and mechanisms underlying ontogenetic variation in indirect defenses, (ii) the relative importance of environmental and genetic components shaping these ontogenetic trajectories, and (iii) the consequences of these ontogenetic trajectories on plant fitness. Advances in this area will shed light on the context dependency of bottom-up and top-down controls of herbivore populations and on how natural selection actually shapes the ontogenetic trajectories of these traits. [Copyright &y& Elsevier]

Myrmecodia tuberosa Jack (Rubiaceae) has been used as part of traditional Indonesian remedies for a wide range of therapeutic usages in West Papua. Our preliminary study revealed the significant potency of these plant extracts and fractions as an immunomodulator by an in vitro technique on Balb/c mice. This study explored the effect of M. tuberosa hypocotyl ethanol extract on the TCD4+ and TCD8+ cell profiles of doxorubicin (Dox)-induced immune-suppressed Sprague Dawley (SD) rats by an in vivo method. Dried powder of M. tuberosa hypocotyl was macerated in 95% ethanol. Following solvent evaporation in a vacuum, the ethanol extract (EE) was partitioned to yield an n-hexane fraction (FH) and residue (FNH). FNH was further partitioned to yield ethyl acetate (FEtOAc) and water fractions (FW). The extract and fractions in the concentrations 10, 20, 50, and 100 ug/mL were tested on macrophage cells by the latex bead method, while the proliferation of lymphocyte cells was evaluated by the MTT assay. The total phenolic and flavonoid contents of those fractions were evaluated. The active fraction was administrated orally on Dox-induced SD rats for 28 days by an in vivo method to observe the TCD4+ and TCD8+ cell profiles. The in vivo assay showed that the FNH could maintain the number of TCD4+ cells, but not the number of TCD8+ cells. The ED50 observed was 24.24 mg/kg BW. Steroid/terpenoid compounds were detected in this fraction along with the phenolics and flavonoids. The FNH contained 3.548 ± 0.058% GAE of total phenolics and 0.656 ± 0.026% QE of total flavonoids. M. tuberosa hypocotyl extract is a potent immunomodulatory agent and may act as co-chemotherapy in Dox use. [ABSTRACT FROM AUTHOR]

Background and Aims Early ontogenetic stages of myrmecophytic plants are infrequently associated with ants, probably due to constraints on the production of rewards. This study reports for the first time the anatomical and histological limitations constraining the production of extrafloral nectar in young plants, and the implications that the absence of protective ants imposes for plants early during their ontogeny are discussed. Methods Juvenile, pre-reproductive and reproductive plants of Turnera velutina were selected in a natural population and their extrafloral nectaries (EFNs) per leaf were quantified. The anatomical and morphological changes in EFNs during plant ontogeny were studied using scanning electron and light microscopy. Extrafloral nectar volume and sugar concentration were determined as well as the number of patrolling ants. Key Results Juvenile plants were unable to secrete or contain nectar. Pre-reproductive plants secreted and contained nectar drops, but the highest production was achieved at the reproductive stage when the gland is fully cup-shaped and the secretory epidermis duplicates. No ants were observed in juvenile plants, and reproductive individuals received greater ant patrolling than pre-reproductive individuals. The issue of the mechanism of extrafloral nectar release in T. velutina was solved given that we found an anatomical, transcuticular pore that forms a channel-like structure and allows nectar to flow outward from the gland. Conclusions Juvenile stages had no ant protection against herbivores probably due to resource limitation but also due to anatomical constraints. The results are consistent with the growth-differentiation balance hypothesis. As plants age, they increase in size and have larger nutrient-acquiring, photosynthetic and storage capacity, so they are able to invest in defence via specialized organs, such as EFNs. Hence, the more vulnerable juvenile stage should rely on other defensive strategies to reduce the negative impacts of herbivory. [ABSTRACT FROM AUTHOR]

Some tropical plant species possess hollow structures (domatia) occupied by ants that protect the plant and in some cases also provide it with nutrients. Most plant-ants tend patches of chaetothyrialean fungi within domatia. In a few systems it has been shown that the ants manure the fungal patches and use them as a food source, indicating agricultural practices. However, the identity of these fungi has been investigated only in a few samples. To examine the specificity and constancy of ant-plant-fungus interactions we characterised the content of fungal patches in an extensive sampling of three ant-plant symbioses (Petalomyrmex phylax/Leonardoxa africana subsp. africana, Aphomomyrmex afer/Leonardoxa africana subsp. letouzeyi and Tetraponera aethiops/Barteria fistulosa) by sequencing the Internal Transcribed Spacers of ribosomal DNA. For each system the content of fungal patches was constant over individuals and populations. Each symbiosis was associated with a specific, dominant, primary fungal taxon, and to a lesser extent, with one or two specific secondary taxa, all of the order Chaetothyriales. A single fungal patch sometimes contained both a primary and a secondary taxon. In one system, two founding queens were found with the primary fungal taxon only, one that was shown in a previous study to be consumed preferentially. Because the different ant-plant symbioses studied have evolved independently, the high specificity and constancy we observed in the composition of the fungal patches have evolved repeatedly. Specificity and constancy also characterize other cases of agriculture by insects. [ABSTRACT FROM AUTHOR]

Myrmecophily is uncommon in spiders and adaptations that allow spider infiltration of ant colonies are poorly studied. Here, a novel interaction between the orb-weaver spider, Eustala oblonga Chickering, and the acacia ant, Pseudomyrmex satanicus Wheeler, in central Panama is documented., These spiders occupy webs at night, but spend most of the day crouched directly against the surface of their host acacias ( Acacia melanocerus Fabaceae) amidst the plant-defending ants. Detailed behavioural observations indicated that the spiders generally occupied areas on the acacias patrolled more actively by ants, but were attacked only if the spiders moved, which happened very infrequently. We hypothesized, therefore, that the spiders avoid ant aggression behaviourally by being still and not reacting to encounters by patrolling ants., We tested this hypothesis experimentally by comparing ant responses to moving versus immobilised E. oblonga and moving versus immobilised individuals of another plant-inhabiting, orb-weaver spider ( Argiope argentata Fabricius) not naturally found on ant-acacias. Consistent with the hypothesis, ants responded significantly more aggressively to moving spiders of both species than to immobilised spiders., Further, moving E. oblonga utilised a particular method of escape in which they suspended themselves on a dragline until ant activity waned before returning to the plant surface and crouching quietly without further agitating the ants. In contrast, moving A. argentata attempted to outrun the ants, thus, continuing to agitate them until the spiders were killed or dropped to the ground., Our results suggest that E. oblonga may be able to inhabit ant-defended acacias essentially by hiding in plain sight. [ABSTRACT FROM AUTHOR]

In East Africa, up to four symbiotic ant species associate with the obligate myrmecophyte Acacia drepanolobium. These ant species differ in the extent to which they defend their host trees from both vertebrate and invertebrate herbivores, but other potential roles of ants in tree defense have not been studied. We investigate the distribution of a new species of parasitic midge targeting A. drepanolobium in a region where A. drepanolobium is inhabited almost exclusively by two ant species- Crematogaster nigriceps and C. mimosae. We find that the frequency of infestation correlates strongly with the identity of the ant occupant: trees inhabited by C. nigriceps are significantly less likely to be infested with parasitic midges. Although the two ant species responded similarly to simulated large herbivore disturbances, trees inhabited by C. nigriceps also had a lower invertebrate load than trees inhabited by C. mimosae. We suggest that differences in defensive behavior towards invertebrates could be one explanation of the observed differences in infestation of A. drepanolobium by parasitic midges. [ABSTRACT FROM AUTHOR]

Abstract: The four species of the central African genus Barteria show variation in habitat and in degree of association with ants. Whereas B. solida, restricted to submontane forests, attracts opportunistic ants to extrafloral nectar, the three other species, found in lowland rainforests (B. fistulosa, B. dewevrei) and in littoral scrub (B. nigritana), possess stem domatia of varying shapes and degrees of specialisation, hosting either non-specific arboreal ants (B. nigritana, some B. dewevrei) or two large species of ants of the genus Tetraponera Smith, 1852 that are specific to some species of Barteria (B. fistulosa, some B. dewevrei). We aimed to investigate whether this variation represents an evolutionary trend toward increasing specialisation of mutualism or the reduction or loss of myrmecophytic traits. For this, we determined phylogenetic relationships within the genus using DNA sequences (primarily nuclear ITS) and microsatellite genotypes (11 loci) on a large sample of individuals, mostly from Cameroon and Gabon. The two types of markers support an initial dichotomy that groups B. dewevrei with B. nigritana and B. fistulosa with B. solida respectively. Within these pairs, species do not appear reciprocally monophyletic. At microsatellite loci, B. nigritana forms a clade embedded within B. dewevrei; and within both B. solida and B. fistulosa, geographical populations show levels of differentiation similar to that observed between populations of B. solida and B. fistulosa. Geographic distance alone does not account for genetic differentiation between species, which indicates reproductive isolation. Divergence in each of the two pairs implies evolutionary transitions in habitat and in myrmecophytism. Specialised mutualism with specific ant species of the genus Tetraponera has been lost in species found in more marginal habitats. [Copyright &y& Elsevier]