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Background
Ant colonies are plagued by a diversity of arthropod guests, which adopt various strategies to avoid or to withstand host attacks. Chemical mimicry of host recognition cues is, for example, a common integration strategy of ant guests. The morphological gestalt and body size of ant guests have long been argued to also affect host hostilit...
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Context 1
... studied the ants' behavior towards ecitophiles in laboratory settings at the field site. We examined ant behavior towards 314 ecitophiles belonging to 29 species (Table 2). These included twelve rove beetle species, six histerid beetle species, three ptiliid beetle species, one water scavenger beetle species, six phorid fly species, and one silverfish species (Table 2; Additional file 1). ...Context 2
... examined ant behavior towards 314 ecitophiles belonging to 29 species (Table 2). These included twelve rove beetle species, six histerid beetle species, three ptiliid beetle species, one water scavenger beetle species, six phorid fly species, and one silverfish species (Table 2; Additional file 1). Ecitophiles were exclusively tested with workers from their colony of origin. ...Context 3
... this study, we distinguished five types of morphological gestalt: protective, myrmecoid, staphylinid-like, phorid-like, and larval-shaped (Fig. 1a-A-F). Note that the morphological gestalt went hand in hand with a rather close phylogenetic relationship of ecitophiles in all but the specimens of the protective gestalt (Table 2). This means we did not have phylogenetically independent replicates for most gestalts. ...Context 4
... reader should thus be aware that we cannot disentangle the influence of morphological gestalt from possible confounding factors caused by close phylogenetic relationship. Table 2 gives an overview of phylogenetic relationships and the morphological gestalt of each species, allowing the reader to assess the phylogenetic diversity for each morphological gestalt. ...Context 5
... 'protective gestalt' (also denoted as "Trutztypus" or "Schutzgestalt" by Wasmann and others; [2,[43][44][45]) includes teardrop-shaped species and species with a globular-protective morphology (Fig. 1a-B,C). The present study included six beetle species and one silverfish species of the teardrop-shaped gestalt (also denoted as "Schutzdach-Typus" or "Limulus-Gestalt" by Wasmann [43]) (Table 2; Additional file 1). These limuloids are characterized by laterally expanded body plates (pronotum and elytra in beetles; pro-, meso-and metanotum in silverfish) that form a protective shield, underneath which the head and most appendages can be retracted [2,51]. ...Context 6
... histerids, the appendages and the head are retractable into anatomical cavities, leaving the ants little to no point of attack (denoted as "Trutztypus" [45]; for more details see [14,45,53,56]). Our study included seven histerid species and one water scavenger beetle (Table 2; Additional file 1). The 'myrmecoid gestalt' (denoted as "Mimikry Typus" by Wasmann [43]) possesses no obvious protective structures but instead anatomically resembles ant workers by having a narrowed waist with expanded abdomen (petiolate abdomen), geniculate antennae, and long legs relative to body size (e.g., [14,42,47]; Fig. 1a- A). ...Context 7
... 'myrmecoid gestalt' (denoted as "Mimikry Typus" by Wasmann [43]) possesses no obvious protective structures but instead anatomically resembles ant workers by having a narrowed waist with expanded abdomen (petiolate abdomen), geniculate antennae, and long legs relative to body size (e.g., [14,42,47]; Fig. 1a- A). Five species of myrmecoid beetles were included in the present study (Table 2; Additional file 1). Species possessing the typical 'staphylinid-like gestalt' (denoted as "indifferent Typus" by Wasmann [43]) have a slender, elongate body shape, short elytra, and a flexible abdomen without expressing petiolate abdominal structures like in myrmecoids (see also [14,91]; Fig. 1a-F). ...Context 8
... have the general appearance of staphylinid beetles and differ little in their morphology from their free-living relatives. This study included six species with such a gestalt (Table 2). We defined the 'larval-shaped gestalt' to have a slender, elongate body shape with a weak level of sclerotization and pronounced body setation (see [76]). ...Context 9
... defined the 'larval-shaped gestalt' to have a slender, elongate body shape with a weak level of sclerotization and pronounced body setation (see [76]). This gestalt solely included the larvae of three Vatesus beetle species ( Fig. 1a-D; Table 2; Additional file 1). Lastly, all phorid fly species were defined here as the 'phorid-like gestalt' (Fig. 1a-E; Table 2), which was characterized by extremely elongated legs relative to the rest of the body, as well as a somewhat globular appearance with a weak level of sclerotization compared to beetles (for details see [2,92]). ...Context 10
... all phorid fly species were defined here as the 'phorid-like gestalt' (Fig. 1a-E; Table 2), which was characterized by extremely elongated legs relative to the rest of the body, as well as a somewhat globular appearance with a weak level of sclerotization compared to beetles (for details see [2,92]). Six species of phorid flies were included in this study (Table 2; Additional file 1). ...Context 11
... ecitophiles' dry weight had a significant effect on the level of received host aggression ( Table 3), in that ant aggression increased with increasing dry weight (Fig. 3a). Small ecitophiles such as phorid flies (genera Ecitophora, Ecituncula, Thalloptera), ptiliid beetles of the genus Limulodes and staphylinid beetles of the genus Myrmedonota were rarely attacked by ants (Table 2). For instance, only five specimens were attacked out of those 55 specimens having a dry weight of less than 0.30 mg (phorid flies: 39 specimens; ptiliid beetles: 5 specimens; rove beetles: 11 specimens; Additional file 1). ...Context 12
... we found no clear overall effect of CHC host similarity on host aggression (Table 2), but a significant interaction between CHC host similarity and Fig. 3 Ant aggression towards ecitophiles in relation to their a dry weight and b CHC host similarity. The aggression index gives the sum of aggressive interactions (attempt of chasing, snapping, stinging, and seizing) divided by the total number of contacts. ...Context 13
... army ant workers primarily attacked ecitophiles with either a protective or a staphylinid-like gestalt, except for diminutive species of these gestalts ( Table 2). Guests of other gestalts received minimal levels of aggression, which indicated that the morphological gestalt is relevant in context of host defensive responses, as indicated but not explicitly tested previously [2,4,13,14,19,55,68,78]. ...Context 14
... of other gestalts received minimal levels of aggression, which indicated that the morphological gestalt is relevant in context of host defensive responses, as indicated but not explicitly tested previously [2,4,13,14,19,55,68,78]. However, this interpretation needs to be treated with caution because our study lacked phylogenetically independent replicates in all morphological gestalts except for the protective gestalt (Table 2). ...Context 15
... with a protective gestalt had vastly different phylogenetic backgrounds (Table 2). Evidently, morphological shielding protected the limuloid-shaped guests during ant attacks (see also [13,14,26,49,98]; Additional file 5). ...Context 16
... genus Myrmedonota belongs to the same staphylinid tribe as Tetradonia, 'false Lomechusini'-a group of Neotropical aleocharine rove beetles formally placed in the tribe Lomechusini [106]. Species of these two genera were relatively small (dry weight ≤ 0.82 mg; N = 130; Table 2), swiftly moving, and non-integrated aleocharine rove beetles with efficient escape responses during attacks-probably the most common strategy of staphylinids to counteract ants [2,14,43]. As discussed above for limuloid guests, these swift escape responses might be an important factor eliciting host aggression irrespective of the guest's morphological gestalt. ...Context 17
... is remarkable as most specimens were relatively large (mean dry weight = 1.80 mg; range = 0.37-3.79 mg; N = 49) and their resemblance of chemical host recognition cues was comparably weak ( Fig. 1d; Table 2). As commonly suggested for social insect symbionts in general [25,94,94,126,127], the minimal concentrations of CHCs in Vatesus larvae might have hampered the host's chemical recognition (chemical hiding sensu [32]; chemical insignificant sensu [24,36]; Additional file 3: experiment 1). ...Context 18
... to myrmecoids and Vatesus larvae, host contacts were overall rare in specimens of the phorid-like gestalt (Fig. 1b). This gestalt included solely flies from the family Phoridae (Table 2), so that its members shared many additional phenotypic traits besides their morphology. For instance, these miniature ecitophiles efficiently avoided contacts with ants by moving away promptly in their typical stop-and-go, zigzag manner, often before physical contact even (see also [49,131]). ...Similar publications
Foraging individuals optimize spatial movement to maximize resource use in
heterogeneous environments. Colonies of Eciton burchellii, a neotropical species
of army ant, forage as an army, consuming broad arrays of arthropod and social
insect prey. Prey depletion in foraging paths exacerbates resource heterogeneity
for E. burchellii and may encourag...
Citations
... Small individuals tend to penetrate unnoticed in ant nests, such as Allopeas gracile Hutton, 1834, Paropeas achatinaceum Pfeiffer, 1846, and Subulina octona Bruguière, 1789, which were ignored by L. processionalis distinguenda (Witte et al. 2002). The influence of size in myrmecophiles-ants interactions results also observed in other groups as beetles and spiders (Stoeffler et al. 2011;von Beeren et al. 2012;von Beeren et al. 2021;Pérez-Lachaud et al. 2023). Other molluscs rely on physical protection provided by the shell and secretions (mucus) to defend themselves against ant attacks (Witte et al. 2002). ...
Ants are a ubiquitous, diverse, and ecologically dominant group that uses different types of substrates for nesting. These nests provide protection and food in a temperature-and humidity-stable environment, which attracts numerous organisms that live in association with these social insects. The interactions between ants and some myrmecophilous groups, such as coleopterans and lepidopterans, have been widely studied, while other groups, such as gastropods, have received less attention. In this study, we present observations of the interactions between the Neotropical ponerine ant Neoponera verenae and terrestrial gastropods. We found 56 individuals belonging to four families, seven genera, and eight species of terrestrial gastropods in ant nests established in three types of substrates (dry cocoa pod, soil, and decaying wood trunk) in the Atlantic Forest Biome. The most frequent genera were Allopeas and Leptinaria (Achatinidae), which accounted for 57.1% of the observed specimens. The gastropods mainly used the shelter provided by ant nests, their favourable and stable microclimatic conditions, and the abundant food resources stored in waste chambers. Young and adult individuals of Leptinaria sp. were found in ant nests, but no aggressive or predatory behaviours were recorded in interactions between ants and gastropods. Our study includes unpublished records of ant nest commensals and presents hypotheses on the close interactions between gastropods and ants.
... Histeridae are robust beetles characterized, in general, by a broadly globular body shape and protective morphological structures complemented by the ability to retract the head and appendages into anatomical cavities, which further protect against attack 5,16,[57][58][59] . According to Parker and Kronauer 60 , such a protective anatomical ground plan of histerids and some other beetles such as aleocharine staphylinids, predisposed these beetles to myrmecophily. ...
... Many clown beetle species, primarily in the subfamilies Haeteriinae and Chlamydopsinae, are www.nature.com/scientificreports/ known to be associated with ants in diverse ways and several are entirely ant-dependent, displaying complex strategies to integrate the host nests and cope with worker aggressiveness 16,59,61 . Less is known, however, about myrmecophilous species belonging to other subfamilies, although associations with ants have been reported on various occasions 13,62 . ...
... Unspecialized, unwelcome ant guests are known to use simple behavioral strategies to escape host detection, such as prudent behavior 66 . Besides slow movement, small size seems to contribute to evade ant aggression: myrmecophiles much smaller than their host are, in general, mostly ignored while those that match the host's size are attacked 59 . As shown in a previous study, most arthropod species associated with N. villosa established in A. bracteata are small body size arthropods relative to their host (workers are 12-13 mm), mainly Coleoptera (various species of Staphylinidae, Ptiliidae, Nitidulidae) and Hymenoptera (other small ant species or small parasitoid wasps) 35 . ...
A new clown beetle species, Bacanius neoponerae , is described from Mexican nests of the arboreal ponerine ant Neoponera villosa found in the tank bromeliad Aechmea bracteata . Adult beetles were found in brood chambers or inner refuse piles, but also outside the ant nests, in decaying organic matter between the bromeliad leaves. No direct interactions between ants and microhisterid beetles could be observed. Several lines of evidence suggest a close relationship either with the ants, specific microhabitats within the ant nests or the bromeliads. Sample site elevation, colony size, monthly rainfall and collecting site were the main variables predicting the association. Almost half of the N. villosa colonies were associated with the microhisterids, and larger colonies favored their presence , especially during the driest months of the year. Two specimens were found in a nest of another ant species, Camponotus atriceps, also inhabiting A. bracteata . The new species is the seventh of the genus Bacanius reported from Mexico. This is the second time a species of this genus is associated with ants, and the fourth record of a histerid beetle cohabiting with ponerine ants. The small size of these beetles and their very protective body structure may facilitate their cohabitation with such aggressive hosts.
... On the other hand, the possible role of some hydrocarbons-related chemical traits (reduced abundance of certain CHC classes), which may help them to invade the host nest by reducing host detection, need to be formally tested in future studies. However, morphological adaptations, including a robust, heavily sclerotized body, seem to be widespread as alternative/additional strategy to chemical strategies in brood parasitic insects (Kistner 1979;Cervo 1994;Tishechkin et al. 2017;von Beeren et al. 2021) and could be important traits favouring nest invasion in velvet ants. otherwise in a credit line to the material. ...
Although recognition using cuticular chemistry is important for host–parasite interactions within aculeate Hymenoptera,
cuticular hydrocarbon (CHC) profles of only a few host–parasite pairs were characterized and compared. One largely
neglected family in this context is the Mutillidae (velvet ants), whose species are ectoparasitoids of bees and wasps. In our
study, we characterized and compared the CHC profles of fve species of Mutillidae and seven host species. The CHC profle
of velvet ants difered among species and included large proportions of n-alkanes and methyl-branched alkanes. Alkenes were
much less abundant in the CHC profles of three species of velvet ants compared with their hosts, while the other two spe-
cies possess a much lower abundance of methyl-branched alkanes than their hosts. Both the number of peaks and compound
diversity were generally higher in velvet ants compared with their hosts. Thus, CHC profles of parasitoids did not show signs
of mimicry when compared with their hosts. In dyadic encounters between one species of velvet ant and its host bee species,
the parasitoid mainly avoided interacting, while aggression by the host was rare. Our results suggest that velvet ants did not
evolve chemical mimicry, perhaps in accordance with their wide host spectrum which would limit chemical specialization.
However, the reduction of alkenes in social bee-attacking species and the reduction of methyl-branched alkanes in social
wasp-attacking species may favour host nest invasion, since these two CHC classes are known to be important in nestmate
recognition for social bees and wasps, respectively. A larger, phylogeny-corrected comparison of Mutillidae and hosts may
help clarifying the evolution of the CHC profle of these parasitoids.
... The latter group spans a gradient of host specificity with species showing no specific host association, to host-specific species that are mainly restricted to the nests of a single ant genus, especially Messor or Aphaenogaster [40]. Previous research suggested the use of different chemical deception strategies in myrmecophilous silverfish with Malayatelura ponerophila and Trichatelura manni displaying chemical resemblance and two unidentified species employing chemical insignificance [28,39,42,43]. In contrast to other myrmecophilous groups such as beetles and flies [33], there is apparently limited morphological divergence between host-specialist and generalist species and even to freeliving relatives. ...
... We did not compare the silverfish CHC concentrations with those of the host ants. The body shapes of ants and silverfish are completely different, which makes comparisons in CHC concentrations, based on dry weight as proxy for surface area, inaccurate (see discussion Additional file 3 in [43]). ...
... The production of a host-specific signal is known as chemical mimicry and has been demonstrated in well integrated social insect guests using radioactive isotopes [58,59] or by showing that the profile was retained in isolation from the host [28,60]. The generalist species Neoasterolepisma curtiseta and the facultative species Lepisma baetica were able to flexibly match their chemical profile to host species with very different profiles similar to other non-host specific myrmecophiles, such as Myrmecophilus crickets [61] and different beetles and the silverfish Trichatelura manni associated with different army ant species [43]. After moulting, N. curtiseta was no longer a mimic of its host and carried an idiosyncratic profile irrespective of its original hosts. ...
Background
Host range is a fundamental trait to understand the ecological and evolutionary dynamics of symbionts. Increasing host specificity is expected to be accompanied with specialization in different symbiont traits. We tested this specificity-specialization association in a large group of 16 ant-associated silverfish species by linking their level of host specificity to their degree of behavioural integration into the colony and to their accuracy of chemically imitating the host’s recognition system, i.e. the cuticular hydrocarbon (CHC) profile.
Results
As expected, facultative associates and host generalists (targeting multiple unrelated ants) tend to avoid the host, whereas host-specialists (typically restricted to Messor ants) were bolder, approached the host and allowed inspection. Generalists and host specialists regularly followed a host worker, unlike the other silverfish. Host aggression was extremely high toward non-ant-associated silverfish and modest to low in ant-associated groups. Surprisingly, the degree of chemical deception was not linked to host specificity as most silverfish, including facultative ant associates, imitated the host’s CHC profile. Messor specialists retained the same CHC profile as the host after moulting, in contrast to a host generalist, suggesting an active production of the cues (chemical mimicry). Host generalist and facultative associates flexibly copied the highly different CHC profiles of alternative host species, pointing at passive acquisition (chemical camouflage) of the host’s odour.
Conclusions
Overall, we found that behaviour that seems to facilitate the integration in the host colony was more pronounced in host specialist silverfish. Chemical deception, however, was employed by all ant-associated species, irrespective of their degree of host specificity.
... Following publication of the original article [1], some errors were found in the online article: ...
... Author details 1 ...
The transmission of microbial symbionts across animal species could strongly affect their biology and evolution, but our understanding of transmission patterns and dynamics is limited. Army ants (Formicidae: Dorylinae) and their hundreds of closely associated insect guest species (myrmecophiles) can provide unique insights into interspecific microbial symbiont sharing. Here, we compared the microbiota of workers and larvae of the army ant Eciton burchellii with those of 13 myrmecophile beetle species using 16S rRNA amplicon sequencing. We found that the previously characterized specialized bacterial symbionts of army ant workers were largely absent from ant larvae and myrmecophiles, whose microbial communities were usually dominated by Rickettsia , Wolbachia , Rickettsiella and/or Weissella . Strikingly, different species of myrmecophiles and ant larvae often shared identical 16S rRNA genotypes of these common bacteria. Protein‐coding gene sequences confirmed the close relationship of Weissella strains colonizing army ant larvae, some workers and several myrmecophile species. Unexpectedly, these strains were also similar to strains infecting dissimilar animals inhabiting very different habitats: trout and whales. Together, our data show that closely interacting species can share much of their microbiota, and some versatile microbial species can inhabit and possibly transmit across a diverse range of hosts and environments.
Army ants provide nourishment to a large variety of animals. This includes birds that feed on animals flushed out by army ant raids, symbiotic arthropods that consume the ants' prey or their brood, and other arthropods that scavenge on army ant refuse deposits. The latter have not received much attention, and the few published studies lack detailed species identifications. Here we provide a first systematic inventory of the beetle fauna associated with refuse deposits of Eciton army ants, with a focus on Eciton burchellii. We collected 8364 adult beetles, 511 larvae, and 24 eggs from 34 deposits at La Selva Biological Station, Costa Rica. We used a combination of DNA barcoding and morphology to identify a subset of 436 specimens to species level. The samples included several new species, and we here formally describe two water scavenger beetles (Hydrophilidae). Refuse deposits harbored a diverse beetle fauna. The identified subset consisted of 91 beetle species from 12 families, with rove beetles being the most abundant and diverse visitors. Of the 85 species found with E. burchellii, 50 species were collected from only one or two refuse deposits. Conversely, seven species were found in 10 or more refuse deposits, indicating a certain level of habitat specialization. We matched adults and immatures for 22 beetle species via DNA barcodes, demonstrating that army ant middens also serve as a beetle nursery. The present survey highlights the significant ecological function of army ants as promoters of biodiversity and their status as keystone species in tropical rainforests.
