The rove beetle Drusilla sparsa (Coleoptera: Staphylinidae) is a myrmecophilous species associated with a myrmicine ant,Crematogaster osakensis (Hymenoptera: Formicidae)

The rove beetle genus Drusilla includes some myrmecophilous species. The Japanese species Drusilla sparsa (Sharp, 1874) has been regarded as a non‐myrmecophilous beetle. In Kagawa Prefecture, Shikoku Island, western Japan, however, we often observed that D. sparsa adults were walking in the vicinity of foraging workers of the myrmicine ant Crematogaster osakensis Forel, 1990. The body color of the beetle is similar to C. osakensis as in other myrmecophilous beetles found near the trails of the host ants. To examine whether D. sparsa is myrmecophilous, we investigated the distribution of D. sparsa and C. osakensis in the field, as well as their behavior including prey preference of the beetle in the laboratory. Drusilla sparsa beetles were collected only in sites where C. osakensis ants occurred. When the beetles encountered the ant workers, they bent the abdominal tip toward the ants. The ants licked the abdominal tip, and then the beetles usually walked away. Such behavioral reaction of the ants was not observed when the beetles encountered workers of the formicine ant Nylanderia flavipes (Smith, 1874) that continuously attacked the beetles. Drusilla sparsa preferred to feed on dead workers of C. osakensis even when other ants were available as food, indicating that D. sparsa is a myrmecophilous species associated with C. osakensis. Crematogaster osakensis was frequently found in the stomach in the ant predator, the Japanese treefrog Hyla japonica Günther, 1859. Thus, the significance of body color similarity between the host ants and beetles is not a case of Batesian mimicry.     

Insights on the association of American Cetoniinae beetles with ants

Cetoniinae beetles (Coleoptera: Scarabaeoidea: Scarabaeidae) can occupy the nests of social insects. In many cases the beetles located within the colonies of social insects encounter a place of shelter and food resources for both adults and immatures. Despite the numerous cohabitation records, the relationship of Cetoniinae beetles with their ant hosts remains mostly unexplored. In this review we provide hypotheses explaining this ant–beetle association. A conceptual model is presented on the processes underpinning the occupation of the nest and the consequences that unfold after occupation, including: (i) death of the ant colony; (ii) death of beetles; and (iii) coexistence. We also provide an exhaustive list of American Cetoniinae beetle species found associated with ants and discuss the symbiotic relationships occurring between the beetles and their host ants.     

The role of resource dispersion in promoting the co‐occurrence of dominant and subordinate ant species

Dominant competitors govern resource use in many communities, leading to predictions of local exclusion and lower species diversity where dominant species are abundant. However, subordinate and dominant species frequently co‐occur. One mechanism that could facilitate resource sharing and co‐occurrence of dominant and subordinate competitors is fine‐scale resource dispersion. Here, we distributed 6 g of a food resource into 1, 2, 8, 32 or 64 units in small 0.40 m² areas centred on nests of the dominant ant Monomorium sydneyense. We tested three hypotheses. First, we hypothesized that the species richness and abundance of foraging ants would increase with increasing resource dispersion. Accordingly, species richness doubled and total ant abundance was two orders of magnitude higher in high resource dispersion treatments. Secondly, we hypothesized that increasing resource dispersion would reduce competitive interactions such as resource turnover events and lower the probability of food resources being occupied. Substantial support for this hypothesis was observed. Finally, we tested the hypothesis that the foraging time of each species would be proportional to the relative abundance of each species solely in high resource dispersion treatments. Expected and observed foraging times were statistically similar for only the dominant ant M. sydneyense. The subdominant Pheidole rugosula increased its foraging time much more than was expected, while two subordinate ants showed no relationship between observed and expected times. Thus, while increasing resource dispersion significantly increased overall species richness, this increase in co‐occurrence did not correlate with a significant increase in foraging time for the two subordinate species. Rather, changes in resource dispersion appeared to benefit only the subdominant species. Inter‐site variation appeared more important for other subordinate species indetermining co‐occurrence and foraging time. Multiple mechanisms facilitate co‐occurrence and resource sharing in this community, and probably in most other communities.     

Ants that associate with Lycaeninae butterfly larvae: diversity, ecology and biogeography

Abstract. Field data on associations of butterfly larvae with ants were collated for 435 species of the subfamily Lycaeninae to analyse patterns in the identity, diversity and ecology of attendant ants. Worldwide, members of at least fifty-three ant genera from six subfamilies associate with Lycaeninae larvae. All these ant genera also forage for other liquid carbohydrate food sources. Species of Crematogaster and Camponotus constitute by far the most important ant associates of Lycaeninae larvae. Diversity of butterfly–ant associations, as measured by Hurlbert rarefaction, is highest in the Oriental, Australian and Nearctic faunal regions, and lower in Africa and the Palaearctic. The Neotropical region could not be assessed separately due to paucity of data. Multiple regression analyses revealed that the number of Lycaeninae species associated with a particular ant genus in a facultatively mutualistic manner is largely determined by the ecological prevalence and geographical distribution, but does not correlate with species richness, of an ant genus. This opportunism is suggested to be the key variable supporting the geographically and taxonomically widespread occurrence of ant–caterpillar mutualism in the Lycaeninae. Obligate interactions are much more specific and almost exclusively involve ecologically dominant ants with long-lived colonies. Neither species richness nor geographical distribution of an ant genus are significant predictors. In such associations, the role of ants shifts from visitors to hosts, and patterns of host use and specificity resemble those known from inquiline ant guests.     

Ant diversity as a direct and indirect driver of pselaphine rove beetle (Coleoptera: Staphylinidae) functional diversity in tropical rainforests,Sabah, Malaysian Borneo

Pselaphinae is a species‐rich beetle subfamily found globally, with many exhibiting myrmecophily—a symbiotic association with ants. Pselaphine–ant associations vary from facultative to obligate, but direct behavioral observations still remain scarce. Pselaphines are speciose and ecologically abundant within tropical leaf litter invertebrate communities where ants dominate, implying a potentially important ecological role that may be affected by habitat disturbances that impact ants. In this study, we measured and analyzed putative functional traits of leaf litter pselaphines associated with myrmecophily through morphometric analysis. We calculated “myrmecophile functional diversity” of pselaphines at different sites and examined this measure's relationship with ant abundance, in both old growth and logged rainforest sites in Sabah, Borneo. We show that myrmecophile functional diversity of pselaphine beetles increases as ant abundance increases. Old growth rainforest sites support a high abundance of ants, which is associated with a high abundance of probable myrmecophilous pselaphines. These results suggest a potential link between adult morphological characters and the functional role these beetles play in rainforest litter as ecological interaction partners with ants.     

New species of the myrmecophile Polyplocotes Westwood (Coleoptera: Ptinidae) from South Australia

Six new species of the Australian myrmecophilous ptinid genus Polyplocotes are described from South Australia. Three are from the deserts of central Australia, one from the Franklin Islands in the Great Australian Bight, one from Eyre Peninsula and one from the Riverland region. Morphologically, the majority of these new species are conventional Polyplocotes , but two are less typical. The characters uniting the genus are explored in the discussion, and comparisons are made to related genera. Although the six new species described here have not been observed in the field, the species of this genus are known to be myrmecophilous, and ant – beetle interactions similar to those seen in other spider beetles might occur between these new species and their host ants.     

The contribution of cacao agroforests to the conservation of lower canopy ant and beetle diversity in Indonesia

The ongoing destruction of tropical rainforests has increased the interest in the potential value of tropical agroforests for the conservation of biodiversity. Traditional, shaded agroforests may support high levels of biodiversity, for some groups even approaching that of undisturbed tropical forests. However, it is unclear to what extent forest fauna is represented in this diversity and how management affects forest fauna in agroforests. We studied lower canopy ant and beetle fauna in cacao agroforests and forests in Central Sulawesi, Indonesia, a region dominated by cacao agroforestry. We compared ant and beetle species richness and composition in forests and cacao agroforests and studied the impact of two aspects of management intensification (the decrease in shade tree diversity and in shade canopy cover) on ant and beetle diversity. The agroforests had three types of shade that represented a decrease in tree diversity (high, intermediate and low diversity). Species richness of ants and beetles in the canopies of the cacao trees was similar to that found in lower canopy forest trees. However, the composition of ant and beetle communities differed greatly between the agroforest and forest sites. Forest beetles suffered profoundly from the conversion to agroforests: only 12.5% of the beetle species recorded in the forest sites were also found in the agroforests and those species made up only 5% of all beetles collected from cacao. In contrast, forest ants were well represented in agroforests, with 75% of all species encountered in the forest sites also occurring on cacao. The reduction of shade tree diversity had no negative effect on ants and beetles on cacao trees. Beetle abundances and non-forest ant species richness even increased with decreasing shade tree diversity. Thinning of the shade canopy was related to a decrease in richness of forest ant species on cacao trees but not of beetles. The contrasting responses of ants and beetles to shade tree management emphasize that conservation plans that focus on one taxonomic group may not work for others. Overall ant and beetle diversity can remain high in shaded agroforests but the conservation of forest ants and beetles in particular depends primarily on the protection of natural forests, which for forest ants can be complemented by the conservation of adjacent shaded cacao agroforests.     

Ectoparasitic "jacks-of-all-trades": relationship between abundance and host specificity in fleas (Siphonaptera) parasitic on small mammals

Animal species with larger local populations tend to be widespread across many localities, whereas species with smaller local populations occur in fewer localities. This pattern is well documented for free-living species and can be explained by the resource breadth hypothesis: the attributes that enable a species to exploit a diversity of resources allow it to attain a broad distribution and high local density. In contrast, for parasitic organisms, the trade-off hypothesis predicts that parasites exploiting many host species will achieve lower mean abundance on those hosts than more host-specific parasites because of the costs of adaptations against multiple defense systems. We test these alternative hypotheses with data on host specificity and abundance of fleas parasitic on small mammals from 20 different regions. Our analyses controlled for phylogenetic influences, differences in host body surface area, and sampling effort. In most regions, we found significant positive relationships between flea abundance and either the number of host species they exploited or the average taxonomic distance among those host species. This was true whether we used mean flea abundance or the maximum abundance they achieved on their optimal host. Although fleas tended to exploit more host species in regions with either larger number of available hosts or more taxonomically diverse host faunas, differences in host faunas between regions had no clear effect on the abundance-host specificity relationship. Overall, the results support the resource breadth hypothesis: fleas exploiting many host species or taxonomically unrelated hosts achieve higher abundance than specialist fleas. We conclude that generalist parasites achieve higher abundance because of a combination of resource availability and stability.     

Host ant use of the Alcon blue butterfly at the northern range margin

In myrmecophilous insects, interactions with ants are often a key factor determining persistence of their populations. Regional variation in host ant use is therefore an essential aspect to consider to provide adequate conservation practices for such species. In this study, we examined this important facet of species’ ecology in an endangered myrmecophilous butterfly Phengaris (=Maculinea) alcon (Lepidoptera, Lycaenidae). The investigations conducted in peripheral populations in Estonia allowed us to expand the knowledge of its host ant use to the northern distribution limit of the species. Our data indicate that in its northernmost populations, the xerophilous ecotype of Phengaris alcon is primarily parasitizing a single host ant species, Myrmica schencki. The data collected are in line with the emerging evidence suggesting that peripheral and core populations of P. alcon use different host ants, and peripheral populations tend to display higher host ant specificity. We also show that, at its northern range margin, P. alcon might be more limited by the availability of its sole larval food plant in the region, Gentiana cruciata, than the densities of its host ant. Finally, we found a strong negative correlation between Myrmica spp. and Lasius spp. colony densities, suggesting that interspecific competition between ants could have a substantial influence on host ant availability of Phengaris butterflies, and thus should be taken into account in conservation plans of these species.     

More individuals but fewer species: testing the ‘more individuals hypothesis’ in a diverse tropical fauna

A positive relationship between species richness and productivity is often observed in nature, but the causes remain contentious. One mechanism, the ‘more individuals hypothesis’ (MIH), predicts richness increases monotonically with density, as a function of resource flux. To test the MIH, we manipulated resource abundance in a community of tropical rainforest litter ants and measured richness and density responses. A unimodal relationship between richness and density most closely fitted the control and disturbance (resource removal) treatments in contrast to expectations of the MIH. Resource addition resulted in a monotonic increase in richness relative to density, a shift from the pattern in the control. In the disturbance treatment, richness was greater than in the control, opposite to expectations of the MIH. While large-scale correlations between ant diversity and net primary productivity or temperature are reconcilable with the MIH, key elements of the hypothesis are not supported.     

Variation in resource size distribution around colonies changes ant–parasitoid interactions

The distribution of resources within habitats affects species abundance, richness and composition, but the role of resource distribution in species interactions is rarely studied. In ant communities, changes in resource distribution within habitats may influence behavioral interactions because many ant species are specialized to efficiently harvest a subset of available resources. This study investigates whether interactions between the behaviorally dominant host ant Pheidole diversipilosa and its specialist parasitoid (Phoridae: Apocephalus orthocladus) depend on resource size distribution around the colony. Using in situ foraging arenas to manipulate parasitoid abundance and resource size distribution around colonies, we tested whether variation in resource size distribution allows P. diversipilosa to alter its foraging behavior in ways that lessen the impact of parasitoid attack. P. diversipilosa colonies do not lower the impact of parasitoid attack by increasing the number of workers foraging individually on small and widely dispersed resources. However, the presence of multiple large resources allows colonies to temporarily redistribute soldier ants from resources patrolled by parasitoids to other resources not patrolled by parasitoids, and to maintain soldier abundance at levels found in the absence of parasitoids. These results highlight the importance of placing behavioral interactions within the context of variation in resource distribution.     

Species traits and environmental characteristics together regulate ant‐associated biodiversity

Host‐associated organisms (e.g., parasites, commensals, and mutualists) may rely on their hosts for only a portion of their life cycle. The life‐history traits and physiology of hosts are well‐known determinants of the biodiversity of their associated organisms. The environmental context may strongly influence this interaction, but the relative roles of host traits and the environment are poorly known for host‐associated communities. We studied the roles of host traits and environmental characteristics affecting ant‐associated mites in semi‐natural constructed grasslands in agricultural landscapes of the Midwest USA. Mites are frequently found in ant nests and also riding on ants in a commensal dispersal relationship known as phoresy. During nonphoretic stages of their development, ant‐associated mites rely on soil or nest resources, which may vary depending on host traits and the environmental context of the colony. We hypothesized that mite diversity is determined by availability of suitable host ant species, soil detrital resources and texture, and habitat disturbance. Results showed that that large‐bodied and widely distributed ant species within grasslands support the most diverse mite assemblages. Mite richness and abundance were predicted by overall ant richness and grassland area, but host traits and environmental predictors varied among ant hosts: mites associated with Aphaenogaster rudis depended on litter depth, while Myrmica americana associates were predicted by host frequency and grassland age. Multivariate ordinations of mite community composition constructed with host ant species as predictors demonstrated host specialization at both the ant species and genus levels, while ordinations with environmental variables showed that ant richness, soil texture, and grassland age also contributed to mite community structure. Our results demonstrate that large‐bodied, locally abundant, and cosmopolitan ant species are especially important regulators of phoretic mite diversity and that their role as hosts is also dependent on the context of the interaction, especially soil resources, texture, site age, and area.     

Pruning of host plant neighbours as defence against enemy ant invasions: <Emphasis Type="Italic">Crematogaster </Emphasis>ant partners of <Emphasis Type="Italic">Macaranga</Emphasis> protected by "wax barriers" prune less than their congeners

Many ant partners of tropical ant-plants prune the leaves and shoot tips of other plants growing around their hosts. According to the hypothesis proposed by Davidson et al. (Ecology 69:801-808), this specialized behaviour not only protects the host plants against overgrowth, but it also conveys a direct benefit to the ant colony as it removes contact points to the neighbouring vegetation where invasions of enemy ants could occur. Here we test this hypothesis by comparing pruning intensity in five closely related Crematogaster (subgenus Decacrema) plant-ant species (and one species of Technomyrmex) that differ in their exposure to competition by other ants. Pruning intensity was quantified by measuring the area loss of paper tape pieces wrapped around the stems of Macaranga host plants. All Crematogaster (Decacrema) ants tested but not Technomyrmex sp. pruned, but the intensity of the behaviour varied strongly between and within species. Pruning was significantly weaker in the three tested Crematogaster species inhabiting Macaranga host plants with a slippery, waxy stem surface, which functions as a mechanical barrier protecting the specific ant partners against generalist competitors. Pruning was generally stronger on more densely ant-populated trees. Even though the number of ants per twig length was lower in associations of ants with glaucous Macaranga hosts, only part of the variation of pruning activity could be explained by "ant density". When corrected for ant density, "wax-running" Crematogaster (Decacrema) ants still pruned more weakly than their congeners inhabiting non-glaucous Macaranga hosts. Pruning is obviously most important when an ant-plant is potentially accessible to intruders, but less necessary when the ant colony is isolated by a protective wax barrier. Our results support the hypothesis that "selfish" defence against invasions is the major selective pressure that has led to the development and maintenance of pruning behaviour in weakly competitive plant-ants.     

Parasite diversity declines with host evolutionary distinctiveness: A global analysis of carnivores

Evolutionarily distinctive host lineages might harbor fewer parasite species because they have fewer opportunities for parasite sharing than hosts having extant close relatives, or because diverse parasite assemblages promote host diversification. We evaluate these hypotheses using data from 930 species of parasites reported to infect free‐living carnivores. We applied nonparametric richness estimators to estimate parasite diversity among well‐sampled carnivore species and assessed how well host evolutionary distinctiveness, relative to other biological and environmental factors, explained variation in estimated parasite diversity. Species richness estimates indicate that the current published literature captures less than 50% of the true parasite diversity for most carnivores. Parasite species richness declined with evolutionary distinctiveness of carnivore hosts (i.e., length of terminal ranches of the phylogeny) and increased with host species body mass and geographic range area. We found no support for the hypothesis that hosts from more diverse lineages support a higher number of generalist parasites, but we did find evidence that parasite assemblages might have driven host lineage diversification through mechanisms linked to sexual selection. Collectively, this work provides strong support for host evolutionary history being an essential predictor of parasite diversity, and offers a simple model for predicting parasite diversity in understudied carnivore species.     

The influence of ants on patterns of colonization and establishment within a set of coexisting lycaenid butterflies in a south-east Asian tropical rain forest

In Peninsular Malaysia ten species of lycaenid butterflies use leaf flushes or inflorescences of the legume tree Saraca thaipingensis as larval hostplant. Resource partitioning among these species is regulated by a complex mixture of patterns of interaction with ants. Females of obligately myrmecophilous species lay their eggs exclusively on trees colonized by their specific host ants. On trees colonized by weaver ants, only specialist mutualists adapted to these territorial ants are able to survive, while larvae of other species are killed. The formicine ant Cladomyrma petalae, which inhabits hollow twigs of the myrmecophytic hostplant, likewise precludes oviposition by female butterflies. Lycaenid larvae confronted with this ant species never survive, but one concealed feeding species (Jamides caeruleus) escapes removal due to the cryptic life-habits of the larvae. Two facultative myrmecophiles associate in a mutualistic way with a wide and largely overlapping range of ant genera which forage at the extrafloral nectaries of leaf flushes. One species (Cheritra freja) is not myrmecophilous, but is tolerated by all but the most territorial ants. Ant-dependent hostplant selection and egg-clustering characterize the obligate mutualists, whereas facultative myrmecophiles and the non-myrmecophile distribute their eggs singly over appropriate hostplants. Signals mediating caterpillar-ant communication are highly specialized in one obligate myrmecophile (Drupadia theda), but rather unspecific in four other species tested. Altogether our observations indicate that colonization and establishment of lycaenid butterflies on S. thaipingensis trees are governed by specializations as well as opportunistic use of resources (ants and hostplant parts). Therefore, the diversity of this species assemblage is maintained by deterministic as well as stochastic factors.     

Ancient host shifts followed by host conservatism in a group of ant parasitoids

While ant colonies serve as host to a diverse array of myrmecophiles, few parasitoids are able to exploit this vast resource. A notable exception is the wasp family Eucharitidae, which is the only family of insects known to exclusively parasitize ants. Worldwide, approximately 700 Eucharitidae species attack five subfamilies across the ant phylogeny. Our goal is to uncover the pattern of eucharitid diversification, including timing of key evolutionary events, biogeographic patterns and potential cophylogeny with ant hosts. We present the most comprehensive molecular phylogeny of Eucharitidae to date, including 44 of the 53 genera and fossil-calibrated estimates of divergence dates. Eucharitidae arose approximately 50 Ma after their hosts, during the time when the major ant lineages were already established and diversifying. We incorporate host association data to test for congruence between eucharitid and ant phylogenies and find that their evolutionary histories are more similar than expected at random. After a series of initial host shifts, clades within Eucharitidae maintained their host affinity. Even after multiple dispersal events to the New World and extensive speciation within biogeographic regions, eucharitids remain parasitic on the same ant subfamilies as their Old World relatives, suggesting host conservatism despite access to a diverse novel ant fauna.     

No evidence of strong host resource segregation by phorid parasitoids of leaf-cutting ants

Resource segregation by species is a cornerstone ecological concept that may result from several processes such as interspecific competition, and can help structuring communities, in particular parasitoid communities. Phorid parasitoid flies that use ants as hosts usually employ one host per individual parasitoid, and thus the pressure for segregating the host resource should be high. At a particular community, these parasitoids might segregate resources by temporal differences in activity patterns, using different host species or nests from those available. Even if parasitoid species coexist on the same nest, they can take advantage of worker polymorphism and task division, searching for ants performing different tasks at different microsites of the same nest. Here we evaluated the segregation of parasitoid species in these hypothesized axes using leaf-cutting ant phorid parasitoids as a model system. We analyzed temporal data collected at two localities with contrasting host species richness; and compared parasitoid co-occurrence at the different niche axis. For most of the hypothesized niche axes tested we found either no departures from random expectations or significantly more niche overlap than expected by chance, ruling out the existence of biologically relevant host resource segregation in this system. However, there was evidence of segregation for some species, since one parasitoid species was only found in winter and another species showed a negative correlation of its abundance over nests with other two species. Furthermore, we found that several species were flexible in host use; Atta phorids varied in average host sizes preferred, whereas Acromyrmex phorids that were generalists were able to use different host species or microsites for host location. From an applied perspective, these results are encouraging when selecting species for the control of leaf-cutting ants because parasitoids coexistence seems to be unaffected by their overlap in niche dimensions.     

Chemical convergence between a guild of facultative myrmecophilous caterpillars and host plants

1. Ants exert strong selective pressure on herbivorous insects, although some caterpillars can live in symbiosis with them using chemical defensive strategies.
2. We investigated the adaptive resemblance of cuticular hydrocarbons (CHCs) in multitrophic systems involving a guild of facultative myrmecophilous caterpillar species (Lepidoptera: Lycaenidae), tending ants (Hymenoptera: Formicidae), and host plants from three families. We hypothesised that the CHCs of the caterpillars would resemble those of their host plants (chemical camouflage).
3. We analysed CHCs using gas chromatography/mass spectrometry. Morisita's similarity index (SI) was used to compare CHC profiles of caterpillar species with different types of ant associations (commensal or mutualistic), ants, and host plants.
4. We found strong convergence between caterpillars' CHCs and plants, especially for commensal species that do not provide secretion rewards for ants. Moreover, we found unexpected chemical convergence among mutualistic (trophobiotic) caterpillar species that offer caloric reward secretions to ants.
5. These results show that the studied caterpillars acquire CHCs through their diet and that they vary according to host plant species and type of ant association (commensalism or mutualism). This ‘chemical camouflage’ of myrmecophilous caterpillars may have arisen as a defensive strategy allowing coexistence with ants on plants, whereas ‘chemical conspicuousness’ may have evolved in the context of honest signalling between mutualistic partners.
6. We suggest the existence of chemical mimicry among myrmecophilous species, especially between mutualistic caterpillars. Cuticular chemical mixtures can play a key adaptive role in decreasing ant attacks and increasing caterpillar survival in multimodal sensory systems.

     

Spatial and temporal variation in host–parasitoid interactions: leafcutter ant hosts and their phorid parasitoids

1. Parasitoid–host interactions are important components of ecological communities. Although parasitoid–host interactions are strongly shaped by evolutionary history, the abundance of both the parasitoid and the host may have a role in determining the nature of the interaction once phylogenetic relationships are considered. 2. Leafcutter ants are hosts of phorid parasitoids and represent a well‐defined and specialised module within a larger network of ant–symbiont interactions. A low specificity host taxa and a positive association between host abundance and parasitoid interaction frequency were expected due to the close phylogenetic relatedness of the hosts. 3. The interactions among all species of leafcutter ants and their parasitoids were quantified in two localities with different species richness. This study also characterised the spatial‐temporal variability of these interactions, determined the patterns of parasitoid specificity and host selection, and tested for an association between host abundance and parasitoid interaction frequency. 4. Contrary to expectation, most parasitoid species were highly specialised and interaction frequency for parasitoid species was not related to host abundance. All host ant species were attacked by more than one phorid species. Some phorid species used more than one host species and showed preference for the same species over space and time, suggesting that there are physiological and/or behavioural restrictions on host use. 5. These results show that there is a tendency for specialisation even when hosts are highly similar in their ecology. From a biological control perspective, these parasitoids may be effective candidates, due to the high specificity of some species and little host‐use variation through time.