Host Ants Research Articles

Finding a nest: Ant‐associated silverfish (Zygentoma: Lepismatidae) moving outside granivorous Messor nests (Hymenoptera: Formicidae)

ABSTRACTAnt nests accommodate a diverse group of strictly associated arthropods. Most of these arthropods are seldom observed outside their host nest, emphasizing significant gaps in our knowledge regarding their biology. We recorded a series of field observations of lepismatid silverfish (Zygentoma: Lepismatidae) moving outside their usual Messor nest habitat in southern Spain and France. We illustrate how they move between different nests and locate nests by closely tracking the foraging trails of their hosts. Additionally, we confirm a prior observation that they can follow their host ants when they migrate to a new nest site. Our observations offer new insights into the hidden biology and the intricate interactions of specialized arthropod symbionts with their hosts within a spatial context.

Characterization of Hibiscus Chlorotic Ringspot Virus-Derived vsiRNAs from Infected Hibiscus rosa-sinensis in China.

Lots of progress have been made about pathogen system of Hibiscus rosa-sinensis and hibiscus chlorotic ringspot virus (HCRSV), however, interactions between H. rosa-sinensis and HCRSV remain largely unknown. Hereon, firstly, HCRSV infection in H. rosa-sinensis from Zhangzhou city of China was confirmed by traditional electron microscopy, modern reverse transcription polymerase chain reaction and RNA-seq methods. Secondly, sequence feature analysis showed the full-length sequence of HCRSV-ZZ was 3,909 nucleotides (nt) in length and had a similar genomic structure with other carmovirus. It contains a 5' untranslated region (UTR), followed by seven open reading frames encoding for P28, P23, P81, P8, P9, P38, and P25, and the last a 3-terminal UTR. Thirdly, HCRSV- ZZ-derived vsiRNAs were identified and characterized for the first time from disease H. rosa-sinensis through sRNA-seq to reveal interactions between pathogen ant plant host. It was shown that the majority of HCRSV-ZZ-derived vsiRNAs were 21 nt, 22 nt, and 20 nt, with 21 nt being most abundant. The 5'-terminal nucleotide of HCRSV-ZZ vsiRNAs preferred U and C. HCRSV-ZZ vsiRNAs derived predominantly (72%) from the viral genome positive-strand RNA. The distribution of HCRSV-ZZ vsiRNAs along the viral genome is generally even, with some hot spots and cold spots forming in local regions. These hot spots and cold spots could be corresponded to the regions of stem loop secondary structures forming in HCRSV-ZZ genome by nucleotide paring. Taken together, our findings certify HCRSV infection in H. rosa-sinensis and provide an insight into interaction between HCRSV and H. rosa-sinensis and contribute to the prevention and treatment of this virus.

Variable viral loads and immune response in an invasive ant's native and introduced ranges

AbstractAimPathogens can play an important role in biological invasions. Introduced populations may be particularly vulnerable to pathogens due to factors such as low genetic diversity and high population density. However, introduced populations that escape their natural pathogens may reallocate resources away from immunity and towards growth and reproduction. Interestingly, introduced ants have been suggested to have increased tolerance to new pathogens, contributing to their success as introduced species. In this study, we aimed to investigate whether introduced Argentine ant populations harbour different viral loads compared to native populations and if these differences were related to immunity‐related gene expression.LocationThe study was conducted across the native range of Argentine ants in Argentina and four introduced regions in California, France, Australia and New Zealand.MethodsWe used RT‐qPCR to quantify viral loads and gene expression in the ants. We analysed 15 different potentially pathogenic viruses across the Argentine ant's native and introduced ranges.ResultsWe found that five viruses, LhuPcV1, LhuPiLV1, LhuCV1, Kashmir Bee virus and LHUV‐1, presented high loads in Argentine ants compared to the other viruses we screened. We found a significant effect of range on viral infections: high viral loads were commonly found in ants from introduced populations, which also exhibited increased immune gene expression. We found highly significant correlations between viral loads and expression of immune and metabolic genes. However, these associations were not fully consistent across the studied regions, indicating the complexity of eco‐immunological phenomena.Main ConclusionsOur results suggest that introduced Argentine ant populations host different viral communities compared to native populations and that these differences are correlated with changes in immunity‐related gene expression. The study highlights the complex role of pathogens in biological invasions and the importance of considering eco‐immunological factors when assessing the impact of introduced species.

Co-habiting ants and silverfish display a converging feeding ecology

BackgroundVarious animal taxa have specialized to living with social hosts. Depending on their level of specialization, these symbiotic animals are characterized by distinct behavioural, chemical, and morphological traits that enable close heterospecific interactions. Despite its functional importance, our understanding of the feeding ecology of animals living with social hosts remains limited. We examined how host specialization of silverfish co-habiting with ants affects several components of their feeding ecology. We combined stable isotope profiling, feeding assays, phylogenetic reconstruction, and microbial community characterization of the Neoasterolepisma silverfish genus and a wider nicoletiid and lepismatid silverfish panel where divergent myrmecophilous lifestyles are observed.ResultsStable isotope profiling (δ13C and δ15N) showed that the isotopic niches of granivorous Messor ants and Messor-specialized Neoasterolepisma exhibit a remarkable overlap within an ant nest. Trophic experiments and gut dissections further supported that these specialized Neoasterolepisma silverfish transitioned to a diet that includes plant seeds. In contrast, the isotopic niches of generalist Neoasterolepisma silverfish and generalist nicoletiid silverfish were clearly different from their ant hosts within the shared nest environment. The impact of the myrmecophilous lifestyle on feeding ecology was also evident in the internal silverfish microbiome. Compared to generalists, Messor-specialists exhibited a higher bacterial density and a higher proportion of heterofermentative lactic acid bacteria. Moreover, the nest environment explained the infection profile (or the 16S rRNA genotypes) of Weissella bacteria in Messor-specialized silverfish and the ant hosts.ConclusionsTogether, we show that social hosts are important determinants for the feeding ecology of symbiotic animals and can induce diet convergence.

Clavigeritae (Coleoptera, Staphylinidae, Pselaphinae) of the Arabian Peninsula with the description of a new species of Corynotopsis Jeannel, 1951 from Oman.

Corynotopsisomanicussp. nov. of the myrmecophilous supertribe Clavigeritae is described from Oman. The type series was collected at night and the ant host species remains unknown. Corynotopsisscotti Jeannel, 1951 is newly recorded for Yemen, and Commatocerusconcinnus Besuchet & Cuccodoro, 2011 for Oman. Lasius Fabricius, 1804 and Lepisiota Santschi, 1926 are, for the first time, determined as hosts of the latter species. The problematic taxonomic status of Corynotopsisscotti is discussed. A distribution map of all Clavigeritae known from the Arabian Peninsula is provided.

Alcon Blues: recent shifts in limiting habitat factors challenge the persistence of an endangered butterfly

Insect habitat specialists have declined more than generalists over the last decades. Understanding how habitat requirements and increased climate variability interact to explain persistence of populations is needed to enable effective conservation measures. Habitat specialists with a complex life cycle, such as myrmecophilous butterflies, are likely to be most vulnerable. Here, we explored to what extent the habitat factors explaining population persistence of the Alcon blue (Phengaris alcon), changed over a 25-year period in the Netherlands, contrasting the recent years 2018–2022 with extreme droughts with the preceding period 1998–2017 characterized by occasional climatic extremes. Population persistence of P. alcon over 1998–2017 as explained by historical habitat conditions was significantly higher in large heathland areas with large patches of its host plant Gentiana pneumonanthe. On the basis of current conditions, population persistence until 2017 was best explained by a combination of host plant area and quality. In contrast, persistence over the recent drought years was most closely associated with increasing occupancy of the optimal host ant Myrmica ruginodis and lower occupancy of competitive and predatory Lasius ants.Implications for insect conservation We conclude that critical habitat conditions change under increasing climatic extremes and that the availability of sufficient optimal host ants has become more critical than that of host plants. The results emphasise that both large-scale hydrological restoration and small-scale management for heterogeneity are necessary to preserve P. alcon and its habitat in the Netherlands. This is also likely to apply to other habitat specialists with complex life cycles from threatened habitats.

Efficiency of emergency conservation methods: a case study of the alcon blue butterfly (Phengaris alcon) and its specific parasitoid

A complicated life history and specific habitat requirements make the Alcon blue butterfly Phengaris alcon a very sensitive species to land-use change. Eggs are oviposited on some Gentiana and Gentianella plants, in whose flowerheads larvae initially feed, after which they continue their development as social parasites in the nests of specific Myrmica ants, once they have been adopted by workers. One of the main threats to their existence is mowing at a time when most individuals are still on gentians. In our research, we tested an emergency conservation method on a site of the butterfly subjected to this kind of pressure in the Białowieża Forest (NE Poland). Previous studies showed that the focal population (dependent on Gentiana pneumonanthe and Myrmica scabrinodis) was characterized by an extremely high density of adults as well as of Ichneumon eumerus, i.e. the rare and specific parasitoid of P. alcon. In mid-August 2020 we performed an unplanned experiment to save caterpillars present in freshly cut plants. We selected about 1800 shoots bearing the eggs or egg shells of the butterfly. Seven hundred and fifty preadoption larvae were transported to the site and placed close to the nests of host ants located in patches without G. pneumonanthe. In the following season we observed that the P. alcon infestation rate of experimental colonies was similar to a control patch, and proportions of parasited pupae did not differ, either.Implications for conservation. Our experiment proved that such actions can be highly effective as emergency conservation methods, and possibly also in (re)introductions of P. alcon.

Impact of Long-Term Floods on Spatial Dynamics of Myrmica scabrinodis, a Host Ant of a Highly Threatened Scarce Large Blue (Phengaris teleius).

Extensively used wet meadows with high species diversity are under threat in Europe by anthropogenic pressure. The increasing frequency of prolonged flooding is emerging as an additional threat to this fragile environment. In our study, we investigated how prolonged flooding affects the spatial distribution and temporal dynamics (through mortality and recolonization process) of the host ant species Myrmica scabrinodis, which is essential for the survival of the endangered Scarce large blue (Phengaris teleius). The study was conducted in the flood-prone Ljubljansko barje plain situated on the southern edge of the species' global range. Prolonged flooding in the study area, possibly affecting the past and current distribution of the host ant M. scabrinodis, was recorded in 2010, 2013, and 2017. In 2020, we set 160 ant traps to estimate the distribution of host ants in a system of meadows covering the entire gradient of flood history. Results indicate that M. scabrinodis survives the flooding for up to three days, starting to disappear if flooding persists longer. After the flooding recedes, ants gradually recolonize empty habitats from the surrounding upland refugia. Our spatial analyses predict that the average recolonization speed was about 29 m per year and that in a year, ants compensate for the mortality effects of 1.8 days of flooding by recolonization in a year. These results show that flooding should be considered as an additional (in some areas, a major) threat to the endangered P. teleius through its deleterious effects on the host ant species.

Population genetic analyses reveal host association and genetically distinct populations of social parasite Solenopsis daguerrei (Hymenoptera: Formicidae)

Inquiline ant social parasites exploit other ant species for their reproductive benefit because they do not possess a worker caste. Due to their relative rarity in nature, the biology and natural history of inquilines are largely unknown. Likewise, not much research exists that details the close relationship between inquilines and their host(s), and how each organism influences the genetic structure of the other. Here, we conducted a comparative population genetics study to assess patterns of genetic structure within and among populations of inquiline Solenopsis daguerrei and its known fire ant hosts, which includes invasive Solenopsis invicta. Using nuclear and mitochondrial markers, we show that four genetically distinct groups of S. daguerrei likely exist, each with different degrees of host association. Consistent with previous inferences of the inquiline lifestyle, we find that inbreeding is common in S. daguerrei, presumably a result of intranidal mating and restricted dispersal. Results from this study, specifically host association patterns, may inform future biological control strategies to mitigate invasive S. invicta populations.

Impact of the dominant competitor on the aggressiveness of host ants toward slave-makers

Abstract Slave-making ants might exert strong pressure on their host populations by pillaging their nests and sometimes destroying the whole colonies. Consequently, host ants have evolved many adaptations reducing the probability of being attacked, resisting an assault or, as a last line of defence, minimising the losses associated with a successful slave-maker invasion. This paper presents the results of a study on a common Palearctic ant species, Formica fusca, which falls victim to slave raids organised by the congeneric F. sanguinea. Slave-making ants were placed close to the nest entrance of the host ants, and the subsequent instances of aggression were recorded. The study was carried out in the context of the influence of the dominant competitor by selecting host colonies located within and outside the territory of the wood ants (F. rufa and F. polyctena). This approach enabled the potential co-evolutionary interplay among three species performing different roles in mutual ecological interactions. The F. fusca ants reacted with aggression to the slave-making ants but not to the dominant competitors. Moreover, the avoidance of the aggression of host ants toward wood ants entails an environment-induced component, besides the presumably inherited one. The impact of the dominant competitor as a territory holder manifests itself in the reduced promptness of F. fusca ants to defend their colonies against slave-makers. The results suggest that this effect is mediated by the negative impact of wood ants on F. fusca colony size.

A new species of Ecitonides Wasmann, 1894 (Coleoptera: Staphylinidae: Paederinae) from Peru and phylogenetic placement of the genus based on molecular data.

Ecitonides constanceae sp. nov., a new species of the myrmecophilous genus Ecitonides Wasmann, 1894, which is associated with army ants (Hymenoptera: Formicidae: Ecitoninae), is described from Peru. The holotype, which is the only known specimen, was collected at light at Los Amigos Biological Station, Madre de Dios department, Peru. The army ant host species is unknown. The new species is distinguished from congeners and an updated key of the species, as well as a checklist of Ecitonides and their associated host ants are provided. Based on the holotype we non-destructively extracted DNA and sequenced two genes which were incorportated into an existing molecular phylogenetic dataset and analysed using Bayesian Inference. Ecitonides is recovered as sister to recently described thermitophilous genus Ruptor ya et al. 2022 and placed in the so-called Medonina and allied taxa clade. Beyond Bayesian Inference phylogenetic analysis and their associated nodal support methods, we also explored the position of the Ecitonides within the posterior sample of trees produced in the Bayesian analyses, which further supported its placement.

Using machine learning to predict protein–protein interactions between a zombie ant fungus and its carpenter ant host

Parasitic fungi produce proteins that modulate virulence, alter host physiology, and trigger host responses. These proteins, classified as a type of “effector,” often act via protein–protein interactions (PPIs). The fungal parasite Ophiocordyceps camponoti-floridani (zombie ant fungus) manipulates Camponotus floridanus (carpenter ant) behavior to promote transmission. The most striking aspect of this behavioral change is a summit disease phenotype where infected hosts ascend and attach to an elevated position. Plausibly, interspecific PPIs drive aspects of Ophiocordyceps infection and host manipulation. Machine learning PPI predictions offer high-throughput methods to produce mechanistic hypotheses on how this behavioral manipulation occurs. Using D-SCRIPT to predict host–parasite PPIs, we found ca. 6000 interactions involving 2083 host proteins and 129 parasite proteins, which are encoded by genes upregulated during manipulated behavior. We identified multiple overrepresentations of functional annotations among these proteins. The strongest signals in the host highlighted neuromodulatory G-protein coupled receptors and oxidation–reduction processes. We also detected Camponotus structural and gene-regulatory proteins. In the parasite, we found enrichment of Ophiocordyceps proteases and frequent involvement of novel small secreted proteins with unknown functions. From these results, we provide new hypotheses on potential parasite effectors and host targets underlying zombie ant behavioral manipulation.

Brain and antennal transcriptomes of host ants reveal potential links between behaviour and the functioning of socially parasitic colonies.

Insect social parasites are characterized by exploiting the hosts' social behaviour. Why exactly hosts direct their caring behaviour towards these parasites and their offspring remains largely unstudied. One hypothesis is that hosts do not perceive their social environment as altered and accept the parasitic colony as their own. We used the ant Leptothorax acervorum, host of the dulotic, obligate social parasite Harpagoxenus sublaevis, to shed light on molecular mechanisms underlying behavioural exploitation by contrasting tissue-specific transcriptomes in young host workers. Host pupae were experimentally (re-)introduced into fragments of their original, another conspecific, heterospecific or parasitic colony. Brain and antennal mRNA was extracted and sequenced from adult ants after they had lived in the experimental colony for at least 50 days after eclosion. The resulting transcriptomes of L. acervorum revealed that ants were indeed affected by their social environment. Host brain transcriptomes were altered by the presence of social parasites, suggesting that the parasitic environment influences brain activity, which may be linked to behavioural changes. Transcriptional activity in the antennae changed most with the presence of unrelated individuals, regardless of whether they were conspecifics or parasites. This suggests early priming of odour perception, which was further supported by sensory perception of odour as an enriched function of differentially expressed genes. Furthermore, gene expression in the antennae, but not in the brain corresponded to ant worker behaviour before sampling. Our study demonstrated that the exploitation of social behaviours by brood parasites correlates with transcriptomic alterations in the central and peripheral nervous systems.

Biological Activities and Ecological Significance of Fire Ant Venom Alkaloids.

Venoms produced by arthropods act as chemical weapons to paralyze prey or deter competitors. The utilization of venom is an essential feature in the biology and ecology of venomous arthropods. Solenopsis fire ants (Hymenoptera: Formicidae) are medically important venomous ants. They have acquired different patterns of venom use to maximize their competitive advantages rendered by the venom when facing different challenges. The major components of fire ant venom are piperidine alkaloids, which have strong insecticidal and antibiotic activities. The alkaloids protect fire ants from pathogens over the course of their lives and can be used to defend them from predators and competitors. They are also utilized by some of the fire ants' natural enemies, such as phorid flies to locate host ants. Collectively, these ants' diverse alkaloid compositions and functions have ecological significance for their survival, successful invasion, and rapid range expansion. The venom alkaloids with powerful biological activities may have played an important role in shaping the assembly of communities in both native and introduced ranges.

The first neotropical ground beetle (Coleoptera, Carabidae) from the Eocene of Ukraine: finding the first Old World ant nest beetle related to Eohomopterus in the Rovno amber

ABSTRACTThe first record of the tribe Paussini Latreille is reported based on a specimen from late Eocene Rovno amber. It is the first known close relative of the genus Eohomopterus (subtribe Carabidomemnina) in the Old World. The recent and Neogene distribution of Eohomopterus is Neotropical, with extant representatives in Ecuador, Brazil and the West Indies, and extinct species in Dominican and Mexican amber. The occurrence of the Neotropical Carabidomemnina in Rovno amber and the presence of the Oriental Protopaussini in Dominican amber are of significant interest as evidence of the probable transarctic migrations of their ant host in the early Eocene.

The influence of parasite load on transcriptional activity and morphology of a cestode and its ant intermediate host.

Parasites with complex life cycles are known to induce phenotypic changes in their intermediate hosts to increase transmission to the final host. The magnitude of these changes could increase with the number of parasites, which would be beneficial to co-infecting parasites. Yet, adverse effects of high parasite load (i.e. many parasites in a single host) might stress both hosts and parasites (e.g. through an increased immune response). We investigated the consequences of parasite load on the transcriptional activity and morphology of the cestode Anomotaenia brevis and its intermediate host, the ant Temnothorax nylanderi. We demonstrated that many differentially expressed host genes shifted with parasite load, and their functions indicate a stronger immune response and fight against oxidative stress in heavily infected hosts. The expression of other host genes responded to infection in an all-or-nothing manner, as did the morphology of the host workers. However, the cestodes became smaller when they competed with other parasites for resources from a single host. Their expression profile further indicated shifts in host immune avoidance, starvation resistance and vesicle-mediated transport. In summary, our study reveals clear consequences of parasite load and highlights specific processes and traits affected by this.

<i>Chrysoritis</i> Butler (Papilionoidea: Lycaenidae: Aphnaeinae) – Part II: Natural history: morphology, ecology, and behaviour, with accounts of larval ecology and insights into the aphytophagous <i>C. dicksoni</i> (Gabriel)

The natural history, morphology, ecology, and behaviour of adults and juveniles of Chrysoritis, and their larval associations with host ants, are described in detail, including insights into the aphytophagous species C. dicksoni.

<i>Chrysoritis</i> Butler (Papilionoidea: Lycaenidae: Aphnaeinae) – Part III: An integrative taxonomic revision

A taxonomic revision of Chrysoritis butterflies based on morphological, ecological and distributional data cross validated with molecular phylogenetic analyses by Quek et al. (2022) is presented. The number of Chrysoritis species is raised from 43 to 49, of which 37 (previously 28) are in the thysbe clade. The taxonomic changes are summarised as follows: Synonymised and reduced to subspecific status: C. chrysaor natalensis stat. nov. (van Son); C. lyncurium lycegenes stat. nov. (Trimen 1874) and C. chrysaor midas stat. nov. (Pennington). Reassigned subspecies: C. zwartbergae rubrescens stat. nov. Heath & Pringle. Elevated to specific status: C. whitei stat. rev. (Dickson); C. wykehami stat. rev. (Dickson); C. mithras stat. rev. (Pringle); C. aridimontis stat. nov. Heath & Pringle; C. amatola stat. nov. (Dickson & McMaster), C. stepheni stat. rev. (Dickson); C. williami stat. rev. Heath and C. lysander stat. rev. (Pennington) from the Kamiesberg area; C. zwartbergae stat. nov (Dickson). The former C. thysbe subspecies osbecki reverts to form, f. osbecki stat. rev. The binomial name pan lysander is no longer in use, being superseded by the above changes. An updated list of larval host plants and host ants for Chrysoritis is provided, as well as the conservation status of each species.

Investigating the Diversity of Wolbachia across the Spiny Ants (Polyrhachis)

Among insects, Wolbachia is an exceedingly common bacterial endosymbiont with a range of consequences of infection. Despite the frequency of Wolbachia infection, very little is known about this bacteria’s diversity and role within hosts, especially within ant hosts. In this study, we analyze the occurrence and diversity of Wolbachia across the spiny ants (Polyrhachis), a large and geographically diverse genus. Polyrhachis samples from throughout the host genus’ phylogenetic and biogeographical range were first screened for single infections of Wolbachia using the wsp gene and Sanger sequencing. The multilocus sequence typing (MLST) scheme was then used on these singly infected samples to identify the Wolbachia strains. A Wolbachia phylogeny was inferred from the Polyrhachis samples analyzed in this study as well as other Formicidae MLST profiles from the MLST online database. We hypothesized that three key host factors were impacting Wolbachia diversity within the Polyrhachis genus: biogeography, phylogeny, and species level. The results suggest that the phylogeny and biogeography of Polyrhachis hosts have no impact on Wolbachia diversity; however, species level may have some limited influence. Additionally, Wolbachia strains appear to group according to being either Old World or New World strains. Among the taxa able to form complete MLST allelic profiles, all twenty are seemingly new strains.

Non-lethal fungal infection could reduce aggression towards strangers in ants

Many parasites interfere with the behaviour of their hosts. In social animals, such as ants, parasitic interference can cause changes on the level of the individual and also on the level of the society. The ant-parasitic fungus Rickia wasmannii influences the behaviour of Myrmica ants by expanding the host’s nestmate recognition template, thereby increasing the chance of the colony accepting infected non-nestmates. Infected ants consistently show an increase of the alkane tricosane (n-C23) in their cuticular hydrocarbon profiles. Although experimental application of single compounds often elicits aggression towards manipulated ants, we hypothesized that the increase of n-C23 might underlie the facilitated acceptance of infected non-nestmates. To test this, we mimicked fungal infection in M. scabrinodis by applying synthetic n-C23 to fresh ant corpses and observed the reaction of infected and uninfected workers to control and manipulated corpses. Infected ants appeared to be more peaceful towards infected but not uninfected non-nestmates. Adding n-C23 to uninfected corpses resulted in reduced aggression in uninfected ants. This supports the hypothesis that n-C23 acts as a ‘pacifying’ signal. Our study indicates that parasitic interference with the nestmate discrimination of host ants might eventually change colony structure by increasing genetic heterogeneity in infected colonies.