Host Ants Research Articles

The Pattern of Social Parasitism in Maculinea teleius Butterfly Is Driven by the Size and Spatial Distribution of the Host Ant Nests

The parasitic relationship between Maculinea butterflies and Myrmica ants has been extensively studied but little information is available on the spatial occurrence of Maculinea larvae. We searched for the presence of Maculinea teleius in 211 ant nests at two sites in two crucial phases of its life cycle, i.e., in autumn, during the initial larval development, and in the following late spring, before pupation. We assessed variations in the proportion of infested nests and factors correlated with spatial distributions of parasites in Myrmica colonies. The parasitism rate in autumn was very high (∼50% of infestation rate) but decreased in the following spring. The most important factor explaining parasite occurrence in both seasons was the nest size. Further factors, such as the presence of other parasites, the Myrmica species or the site, concurred to explain the differential survival of Ma. teleius until the final development. Irrespective of the host nest distribution, the parasite distribution changed from even in autumn to clumped in late spring. Our work showed that the survival of Ma. teleius is correlated with colony features but also with the nest spatial distribution, which therefore should be taken into consideration in conservation strategies aiming at preserving these endangered species.

First Record of the Elusive Ant Parasitoid Horismenus floridensis (Hymenoptera: Eulophidae) in Mexico and New Association with an Ant Host.

Most eulophid wasps are primary parasitoids, mainly of endophytic insect larvae (Diptera, Coleoptera, Lepidoptera, Hymenoptera, Hemiptera, and Thysanoptera), but can also attack spider eggs, gall-forming mites, or nematodes. A few species are known to parasitize ants. Here we report on the occurrence of Horismenus floridensis (Schauff and Bouček) attacking Camponotus atriceps (Smith) in southern Mexico (Campeche), expanding the distribution for this eulophid species and the range of its potential hosts. We also provide an updated list of the Horismenus Walker species found in Mexico, which currently includes 21 identified species. This is the second host ant ever recorded for H. floridensis and the first reliable record of C. atriceps as a host for this eulophid wasp. The first host ant reported from Florida 35years ago was the closely related valid species, C. floridanus (Buckley), erroneously synonymized at that time with C. atriceps (formerly, C. abdominalis (Fabricius)).

Untangling the complex interactions between turtle ants and their microbial partners

BackgroundTo understand the patterns of biodiversity it is important to consider symbiotic interactions as they can shape animal evolution. In several ant genera symbiotic interactions with microbial communities have been shown to have profound impacts for the host. For example, we know that for Camponotini the gut community can upgrade the host’s diet and is shaped by development and colony interactions. However, what is true for one ant group may not be true for another. For the microbial communities that have been examined across ants we see variation in the diversity, host factors that structure these communities, and the function these microbes provide for the host. In the herbivorous turtle ants (Cephalotes) their stable symbiotic interactions with gut bacteria have persisted for 50 million years with the gut bacteria synthesizing essential amino acids that are used by the host. Although we know the function for some of these turtle ant-associated bacteria there are still many open questions.ResultsIn the present study we examined microbial community diversity (16S rRNA and 18S rRNA amplicons) of more than 75 species of turtle ants across different geographic locations and in the context of the host’s phylogenetic history. Our results show (1) that belonging to a certain species and biogeographic regions are relevant to structuring the microbial community of turtle ants; (2) both bacterial and eukaryotic communities demonstrated correlations and cooccurrence within the ant host; (3) within the core bacterial community, Burkholderiaceae bacterial lineage were the only group that showed strong patterns of codiversification with the host, which is remarkable since the core bacterial community is stable and persistent.ConclusionsWe concluded that for the turtle ants there is a diverse and evolutionarily stable core bacterial community, which leads to interesting questions about what microbial or host factors influence when these partner histories become evolutionarily intertwined.

Fungi Associated with Messor Ants on the Balkan Peninsula: First Biogeographical Data

Ant nests’ relatively stable and long-lasting microhabitats present ideal living conditions for many uni- and multicellular organisms, whose relationships range from mutualistic to parasitic. Messor harvester ants inhabit arid and semi-arid open areas where their colonies consist of large numbers of individuals. Due to the high number of other organisms associated with harvester ants, their nests can be defined as islands for unique biota. Despite significant progress in research on ant-associated fungi in Europe, little is still known about the recently described ectoparasitic fungus Rickia lenoirii Santamaria, 2015 (Laboulbeniales), found on two species of ants of the genus Messor. Here we report for the first time the occurrence of the ectoparasitic ant-associated fungus R. lenoirii from three countries (Albania, Bulgaria, and continental Greece) and multiple localities in the Balkans. The fungus was detected on four ant host species—Messor structor (Latreille, 1798), M. wasmanni Krausse, 1910, M. hellenius Agosti & Collingwood, 1987, and M. mcarthuri Steiner et al., 2018 with the latter two representing new host records. Furthermore, spores of the widespread endoparasitic fungus of ants, Myrmicinosporidium durum Hölldobler, 1933 (Blastocladiomycota), were reported for the first time in Messor structor (Bulgaria). Images of the ant-associated Rickia lenoirii taken with a scanning electron microscope, a comparison with R. wasmannii, and a distribution map are also presented.

Natural history and ecological effects on the establishment and fate of Florida carpenter ant cadavers infected by the parasitic manipulator Ophiocordyceps camponoti‐floridani

Abstract Ophiocordyceps fungi manipulate the behaviour of their ant hosts to produce a summit disease phenotype, thereby establishing infected ant cadavers onto vegetation at elevated positions suitable for fungal growth and transmission. Multiple environmental and ecological factors have been proposed to shape the timing, positioning and outcome of these manipulations. We conducted a long‐term field study of Ophiocordyceps camponoti‐floridani infections of Camponotus floridanus ants—the Florida zombie ants. We propose and refine hypotheses on the factors that shape infection outcomes by tracking the occurrence of and fungal growth from hundreds of ant cadavers. We modelled and report these data in relation to weather, light, vegetation and attack by hyperparasites. We investigated environmental factors that could affect the occurrence and location of newly manipulated ant cadavers. New cadaver occurrence was preferentially biased towards epiphytic Tillandsia bromeliads, canopy openness and summer weather conditions (an interactive effect of temperature, humidity and precipitation). Furthermore, we suggest that incident light at the individual cadaver level reflects microhabitat choice by manipulated ants or selective pressure on cadaver maintenance for conditions that improve fungal survival. We also asked which environmental conditions affect fungal fitness. Continued fungal development of reproductive structures and putative transmission increased with moist weather conditions (interaction of humidity and precipitation) and canopy openness, while being reduced by hyperparasitic mycoparasite infections. Moreover, under the most open canopy conditions, we found an atypical Ophiocordyceps growth morphology that could represent a plastic response to conditions influenced by high light levels. Taken together, we explore general trends and the effects of various ecological conditions on host and parasite disease outcomes in the Florida zombie ant system. These insights from the field can be used to inform experimental laboratory setups that directly test the effects of biotic and abiotic factors on fungus–ant interactions or aim to uncover underlying molecular mechanisms. Read the free Plain Language Summary for this article on the Journal blog.

What’s in Your Head, Zombie? Camponotus renggeri Ants Parasitized by the Entomopathogenic Fungus Ophiocordyceps camponoti-renggeri in a Relic of Atlantic Forest in Caatinga Biome, Brazil

Entomopathogenic fungi are widely known to parasitize and manipulate the behavior of various orders of arthropods. In this study, we recorded parasitism involving the entomopathogenic fungus Ophiocordyceps camponoti-renggeri and host ants of the species Camponotus renggeri in a relic of Atlantic Forest in Caatinga biome, in addition to characterizing the environmental and ecological aspects of the interaction. We found 210 infected ant workers, fixed predominantly on the margins of the abaxial face of leaves of the local vegetation. Most ants used simple phyllotaxis leaves for fixation and death, whose size varied widely. The parasitized ants died about 1.5 m above the ground. These results suggest that Ophiocordyceps camponoti-renggeri has high virulence and that the behavioral changes induced in its hosts favor their fitness.

Environments and Hosts Structure the Bacterial Microbiomes of Fungus-Gardening Ants and their Symbiotic Fungus Gardens.

The fungus gardening-ant system is considered a complex, multi-tiered symbiosis, as it is composed of ants, their fungus, and microorganisms associated with either ants or fungus. We examine the bacterial microbiome of Trachymyrmex septentrionalis and Mycetomoellerius turrifex ants and their symbiotic fungus gardens, using 16S rRNA Illumina sequencing, over a region spanning approximately 350km (east and central Texas). Typically, microorganisms can be acquired from a parent colony (vertical transmission) or from the environment (horizontal transmission). Because the symbiosis is characterized by co-dispersal of the ants and fungus, elements of both ant and fungus garden microbiome could be characterized by vertical transmission. The goals of this study were to explore how both the ant and fungus garden bacterial microbiome are acquired. The main findings were that different mechanisms appear to explain the structure the microbiomes of ants and their symbiotic fungus gardens. Ant associated microbiomes had a strong host ant signature, which could be indicative of vertical inheritance of the ant associated bacterial microbiome or an unknown mechanism of active uptake or screening. On the other hand, the bacterial microbiome of the fungus garden was more complex in that some bacterial taxa appear to be structured by the ant host species, whereas others by fungal lineage or the environment (geographic region). Thus bacteria in fungus gardens appear to be acquired both horizontally and vertically.

Evidence for a conserved queen-worker genetic toolkit across slave-making ants and their ant hosts.

The ecological success of social Hymenoptera (ants, bees, wasps) depends on the division of labour between the queen and workers. Each caste exhibits highly specialized morphology, behaviour, and life-history traits, such as lifespan and fecundity. Despite strong defences against alien intruders, insect societies are vulnerable to social parasites, such as workerless inquilines or slave-making ants. Here, we investigate whether gene expression varies in parallel ways between lifestyles (slave-making versus host ants) across five independent origins of ant slavery in the "Formicoxenus-group" of the ant tribe Crematogastrini. As caste differences are often less pronounced in slave-making ants than in nonparasitic ants, we also compare caste-specific gene expression patterns between lifestyles. We demonstrate a substantial overlap in expression differences between queens and workers across taxa, irrespective of lifestyle. Caste affects the transcriptomes much more profoundly than lifestyle, as indicated by 37 times more genes being linked to caste than to lifestyle and by multiple caste-associated modules of coexpressed genes with strong connectivity. However, several genes and one gene module are linked to slave-making across the independent origins of this parasitic lifestyle, pointing to some evolutionary convergence. Finally, we do not find evidence for an interaction between caste and lifestyle, indicating that caste differences in gene expression remain consistent even when species switch to a parasitic lifestyle. Our findings strongly support the existence of a core set of genes whose expression is linked to the queen and worker caste in this ant taxon, as proposed by the "genetic toolkit" hypothesis.

Trophic specialization of a newly described spider ant symbiont, Myrmecicultor chihuahuensis (Araneae: Myrmecicultoridae)

The spider Myrmecicultor chihuahuensis Ramírez, Grismado & Ubick (Myrmecicultoridae) was described in 2019 and hypothesized to be a myrmecophile, living inside the nests of Novomessor (Myrmicinae) and perhaps also Pogonomyrmex (Myrmicinae) ants. To test the hypothesis that M. chihuahuensis are chemical mimics of their host ants, we carried out behavioral bioassays to observe interactions between the spiders and the host ants. We compared the cuticular hydrocarbon (CHC) profiles of the spiders and the ants. We discovered that this new species of spider is a myrmecophage, displaying hunting strategies similar to other myrmecophagous spiders, particularly those in the genus Zodarion Walckenaer, 1826 (Zodariidae). The CHC profile of M. chihuahuensis did not match the profile of the ants with which it associates, Novomessor albisetosus (Mayr), but ants and spider shared several compounds, potentially involved in species recognition.

Phylogenomic analysis and metabolic role reconstruction of mutualistic Rhizobiales hindgut symbionts of Acromyrmex leaf-cutting ants.

Rhizobiales are well-known plant-root nitrogen-fixing symbionts, but the functions of insect-associated Rhizobiales are poorly understood. We obtained genomes of three strains associated with Acromyrmex leaf-cutting ants and show that, in spite of being extracellular gut symbionts, they lost all pathways for essential amino acid biosynthesis, making them fully dependent on their hosts. Comparison with 54 Rhizobiales genomes showed that all insect-associated Rhizobiales lost the ability to fix nitrogen and that the Acromyrmex symbionts had exceptionally also lost the urease genes. However, the Acromyrmex strains share biosynthesis pathways for riboflavin vitamin, queuosine and a wide range of antioxidant enzymes likely to be beneficial for the ant fungus-farming symbiosis. We infer that the Rhizobiales symbionts catabolize excess of fungus-garden-derived arginine to urea, supplementing complementary Mollicutes symbionts that turn arginine into ammonia and infer that these combined symbiont activities stabilize the fungus-farming mutualism. Similar to the Mollicutes symbionts, the Rhizobiales species have fully functional CRISPR/Cas and R-M phage defenses, suggesting that these symbionts are important enough for the ant hosts to have precluded the evolution of metabolically cheaper defenseless strains.

Microclimate influences plant reproductive performance via an antagonistic interaction

Climatic conditions can influence plant reproduction directly, but also via changes in plant traits, interactions with animals, and the surrounding environment. Such indirect effects can often be complex and involve multiple steps including climatic effects on interacting species, and on the context in which these interactions occur. The joint effects of climatic variation and indirect effects in terms of plant-animal interactions have sometimes been assessed at larger spatial scales. However, less is known about how microclimatic variation affects within-population variation in reproductive performance, in spite of that it is becoming increasingly clear that variation in climatic conditions can occur over very short distances. We studied the direct and indirect effects of microclimate on within-population variation in reproductive performance of the plant Gentiana pneumonanthe in presence of the myrmecophagous and seed predator butterfly Phengaris alcon. We found that microclimatic effects on plant performance were mainly indirect, and that effects of temperature and moisture were interactive. The number of seeds per flower of G. pneumonanthe decreased in cold and moist microsites, and these effects were mediated by an increased oviposition by P. alcon in these microsites. The effects of soil temperature and moisture on the incidence of oviposition and plant performance were mediated by effects on plant phenology, density and phenology of neighbouring host plants, and host ant abundance. Plants that flowered earlier and where host ants were more abundant, and especially plants surrounded by fewer and later-flowering neighbours, produced fewer seeds per flower because of a higher incidence of oviposition. Our results demonstrate that effects of microclimatic variation on plant reproductive performance can be mostly indirect and largely mediated by species interactions. These findings highlight that among individual variation in small-scale environmental conditions within populations can cause variation in individual plant performance through multiple pathways.

Molecular Evidence of Chemical Disguise by the Socially Parasitic Spiny Ant Polyrhachis lamellidens (Hymenoptera: Formicidae) When Invading a Host Colony

While most ant species establish a colony independently, some socially parasitic ants build the foundation of their colony by invading other ant (host) colonies and utilizing their labor forces. Many socially parasitic ants disguise their cuticular hydrocarbon (CHC) profile, which is also known as signature mixture for nestmate discrimination, when invading the host colony. Since the strategy of chemical disguise is widespread in socially parasitic ants, elucidating the mechanism of chemical disguise will promote knowledge on the evolutionary history of social parasitism. However, detailed knowledge is still lacking, as the relevant information has only originated from circumstantial evidence, which was obtained from ecological observations. In this study, we investigated the mechanism of chemical disguise in a new queen of a temporary socially parasitic spiny ant (Polyrhachis lamellidens) by measuring its CHC profile, performing a tracing assay with labeled substances, and analyzing gene expression levels. First, after rubbing behavior was observed against the host workers, the CHC profile in P. lamellidens shifted to pronounced peaks that closely resembling that of the host workers. We also observed a reduction in aggressive behaviors by the host ant against P. lamellidens after rubbing behavior was performed. In addition, P. lamellidens acquired artificially-applied labeling substances from host workers through their rubbing behaviors, while gene expression profiling showed the expression of CHC synthesis-related genes did not change during this behavior. These results suggest that P. lamellidens directly obtains host CHCs through rubbing behavior, and these host CHCs enables P. lamellidens to remain disguised during colony invasion.

New Records of the Old World Ant Cricket Myrmecophilus americanus Saussure, 1877 (Orthoptera: Myrmecophilidae) in Mexico with an Updated List of Known Ant Hosts for Its New World Congeners

The Old World ant cricket Myrmecophilus americanus Saussure, 1877 is reported for the first time from Nuevo Leon state, Mexico. The crickets were found living with their obligate host, the Old World ant, Paratrechina longicornis (Latreille, 1802). The list of known ant hosts of native New World Myrmecophilus species is updated.

Illustrated descriptions of juvenile stages of an Aloeides species close to margaretae Tite & Dickson, including comparisons with both A. apicalis Tite & Dickson and A. depicta Tite & Dickson

The butterfly in this study is provisionally treated as Aloeides margaretae and represents observations and material from Moorreesburg, Lambert’s Bay and Graafwater, in the Western Cape province. The juvenile stages illustrated herein were mostly obtained from Graafwater; although they are consistent with observations at the other localities. These juvenile stages are compared with Gowan Clark’s illustrations of A. depicta in Tite & Dickson (1968). Some small differences in markings of the larval stages were noted, that together with a difference in the shape of the hind wing, lend some support for their separate status. A comparison is also made here between the adult stages of A. margaretae and A. apicalis. This reveals little significant or consistent difference between them in either wing shape or markings, inferring that their taxonomic relationship needs to be reviewed in a molecular study. It is surprising that Tite & Dickson did not attempt to define or question the relationship between them seeing that both taxa were described by them in the same publication and that according to their designated paratypes, their distributions overlapped. It is unlikely that species of host plant or host ant can throw any further light on their relationship as there is a dearth of such data in most descriptions of myrmecophilous juveniles, especially in the earlier publications, prompting a plea herein for lepidopterists to add observed host information to the usual collecting data and to collect samples of the host ants wherever possible.

Hijacking time: How Ophiocordyceps fungi could be using ant host clocks to manipulate behavior.

s Ophiocordyceps fungi manipulate ant behaviour as a transmission strategy. Conspicuous changes in the daily timing of disease phenotypes suggest that Ophiocordyceps and other manipulators could be hijacking the host clock. We discuss the available data that support the notion that Ophiocordyceps fungi could be hijacking ant host clocks and consider how altering daily behavioural rhythms could benefit the fungal infection cycle. By reviewing time‐course transcriptomics data for the parasite and the host, we argue that Ophiocordyceps has a light‐entrainable clock that might drive daily expression of candidate manipulation genes. Moreover, ant rhythms are seemingly highly plastic and involved in behavioural division of labour, which could make them susceptible to parasite hijacking. To provisionally test whether the expression of ant behavioural plasticity and rhythmicity genes could be affected by fungal manipulation, we performed a gene co‐expression network analysis on ant time‐course data and linked it to available behavioural manipulation data. We found that behavioural plasticity genes reside in the same modules as those affected during fungal manipulation. These modules showed significant connectivity with rhythmic gene modules, suggesting that Ophiocordyceps could be indirectly affecting the expression of those genes as well.

A new species and new distributional records of Haroldius Boucomont, 1914 (Coleoptera: Scarabaeidae: Scarabaeinae) from southern Africa.

Haroldius lyleae Daniel, Strmpher Snll, new species, is described and illustrated from South Africa. The new species can be easily distinguished from other species of the genus by its notable triangular clypeus lacking the distinctive mid-anterior indentation and denticles present in other Haroldius Boucomont, 1914 species. Monomorium albopilosum Emery, 1895 (Hymenoptera: Formicidae: Myrmicinae) is recorded as a possible ant host of the new species. Haroldius modestus (Janssens, 1953) is recorded from Zimbabwe for the first time, and Haroldius convexus (Philips Scholtz, 2000) is now recorded from the North West and KwaZulu-Natal Provinces of South Africa as well.

Possible impacts of the predominant Bacillus bacteria on the Ophiocordyceps unilateralis s. l. in its infected ant cadavers

Animal hosts infected and killed by parasitoid fungi become nutrient-rich cadavers for saprophytes. Bacteria adapted to colonization of parasitoid fungi can be selected and can predominate in the cadavers, actions that consequently impact the fitness of the parasitoid fungi. In Taiwan, the zombie fungus, Ophiocordyceps unilateralis sensu lato (Clavicipitaceae: Hypocreales), was found to parasitize eight ant species, with preference for a principal host, Polyrhachis moesta. In this study, ant cadavers grew a fungal stroma that was predominated by Bacillus cereus/thuringiensis. The bacterial diversity in the principal ant host was found to be lower than the bacterial diversity in alternative hosts, a situation that might enhance the impact of B. cereus/thuringiensis on the sympatric fungus. The B. cereus/thuringiensis isolates from fungal stroma displayed higher resistance to a specific naphthoquinone (plumbagin) than sympatric bacteria from the environment. Naphthoquinones are known to be produced by O. unilateralis s. l., and hence the resistance displayed by B. cereus/thuringiensis isolates to these compounds suggests an advantage to B. cereus/thuringiensis to grow in the ant cadaver. Bacteria proliferating in the ant cadaver inevitably compete for resources with the fungus. However, the B. cereus/thuringiensis isolates displayed in vitro capabilities of hemolysis, production of hydrolytic enzymes, and antagonistic effects to co-cultured nematodes and entomopathogenic fungi. Thus, co-infection with B. cereus/thuringiensis offers potential benefits to the zombie fungus in killing the host under favorable conditions for reproduction, digesting the host tissue, and protecting the cadaver from being taken over by other consumers. With these potential benefits, the synergistic effect of B. cereus/thuringiensis on O. unilateralis infection is noteworthy given the competitive relationship of these two organisms sharing the same resource.

Braconid parasitoids of ants (Hymenoptera, Braconidae, Euphorinae, Neoneurini) from Baltic amber with a discussion of records of fossil larvae parasitizing ant workers

A new record of the fossil genus Elasmosomites Brues, 1933 from Baltic amber with an illustrated description of a new species, E. arkadylelejisp. nov. and the first description of a male of E. primordialis Brues, 1933 are provided. A key to currently known Neoneurini genera is compiled. A new record of fossil braconid larva emerging from an ant worker of Lasius schiefferdeckeri Mayr, 1868 is discussed and a correction to previous determination of ant hosts from amber is included.

Co-occurrence in ant primary parasitoids: a Camponotus rectangularis colony as host of two eucharitid wasp genera.

Different assemblages of parasitoids may attack a given host species and non-random distribution patterns in parasitoid species assemblages have been reported on various occasions, resulting in co-occurrence at the population, colony, or even individual host levels. This is the case for different closely related species of eucharitid wasps (a family of specialized ant parasitoids) sharing similar niches and co-occurring on the same host at different levels. Here we reviewed all known associations between eucharitid wasps and the ant host genus Camponotus Mayr, 1861 and reported new ant-parasitoid associations. In addition, we report a new case of co-occurrence in eucharitid wasps, at the host colony level, involving a new undescribed species of Pseudochalcura Ashmead, 1904 and an unidentified species of Obeza Heraty, 1985, which attack the common but very poorly known neotropical arboreal ant Camponotus rectangularis Emery, 1890. Most attacks were solitary, but various cocoons were parasitized by two (16%) or three (8%) parasitoids. Globally, parasitism prevalence was very low (3.7%) but showed an important variability among samples. Low parasitism prevalence along with host exposure to parasitoid attack on host plants and overlapping reproductive periods of both parasitoid species may have allowed the evolution of co-occurrence. We also provided some additional data regarding the host ant nesting habits, the colony composition and new symbiotic associations with membracids and pseudococcids. The seemingly polydomous nesting habits of C. rectangularis could play a part in the reduction of parasitism pressure at the population level and, combined with occasionally important local parasitism rates, could also contribute to some parts of the colonies escaping from parasites, polydomy possibly representing an effective parasitism avoidance trait.

Local host ant usage of scarce large blue Phengaris teleius and dusky large blue P. nausithous (Lepidoptera: Lycaenidae) at Goričko Nature Park (NE Slovenia)

In our contribution we report on the local host ants of two threatened and protected butterfly species, the scarce large blue (Phengaris teleius) and the dusky large blue (P. nausithous) at Goričko (NE Slovenia), which hosts one of the largest and the most important metapopulation for both species of large blues in Slovenia. Larvae of both species are developing in Myrmica ant nests and different ant species may be used as larval hosts in different parts of the species range. During our study, seven species of potential host ants of the genus Myrmica were found at 12 selected sampling sites. A total of 142 ant nests were examined for the presence of Phengaris larvae. Larvae of P. teleius were found in 25 nests of three ant species: M. scabrinodis, M. rubra and M. gallienii, while larvae of P. nausithous were found in 9 nests, all of M. rubra. The results of the present study provide the first insight into the local host ants of the two Phengaris species in Slovenia and could serve as an important source for active conservation of both species in Slovenia.