Ophiostomatoid fungi associated with hardwood-infesting bark and ambrosia beetles in Poland: Taxonomic diversity and vector specificity

Fungi in the orders Ophiostomatales and Microascales (Ascomycota), often designated as ophiostomatoid fungi, are frequent associates of scolytine bark and ambrosia beetles that colonize hardwood and coniferous trees. Several species, e.g., Ophiostoma novo-ulmi, are economically damaging pathogens of trees. Because little is known regarding the ophiostomatoid fungi in Europe, we have explored the diversity of these fungi associated with hardwood-infesting beetles in Poland. This study aims to clarify the associations between fungi in the genera Ambrosiella, Graphium (Microascales), Graphilbum, Leptographium, Ophiostoma and Sporothrix (Ophiostomatales) and their beetle vectors in hardwood ecosystems. Samples associated with 18 bark and ambrosia beetle species were collected from 11 stands in Poland. Fungi were isolated from adult beetles and galleries. Isolates were identified based on morphology, DNA sequence comparisons for five gene regions (ITS, LSU, ßT, TEF 1-α, and CAL) and phylogenetic analyses. In total, 36 distinct taxa were identified, including 24 known and 12 currently unknown species. Several associations between fungi and bark and ambrosia beetles were recorded for the first time. In addition, associations between Dryocoetes alni, D. villosus, Hylesinus crenatus, Ernoporus tiliae, Pteleobius vittatus and ophiostomatoid fungi were reported for the first time, and Sporothrix eucastanea was reported for the first time outside of the USA. Among the species of Ophiostomatales, 14 species were in Ophiostoma s. l., two species were in Graphilbum, nine species were in Sporothrix, and seven species were in Leptographium s. l. Among the species of Microascales, three species were in Graphium, and one was in Ambrosiella. Twenty taxa were present on the beetles and in the galleries, twelve only on beetles, and four only in galleries. Bark and ambrosia beetles from hardwoods appear to be regular vectors, with ophiostomatoid fungi present in all the beetle species. Most ophiostomatoid species had a distinct level of vector/host specificity, although Ophiostoma quercus, the most frequently encountered species, also had the greatest range of beetle vectors and tree hosts. Plant pathogenic O. novo-ulmi was found mainly in association with elm-infesting bark beetles (Scolytus multistriatus, S. scolytus, and P. vittatus) and occasionally with H. crenatus on Fraxinus excelsior and with Scolytus intricatus on Quercus robur.     

Habitat and climatic preferences drive invasions of non-native ambrosia beetles in deciduous temperate forests

The introduction of non-native ambrosia beetles can cause severe damage in forest ecosystems. Understanding the environmental drivers affecting their invasion at the local scale is of utmost importance to enhancing management strategies. Our objectives were: (1) to determine the influence of forest composition, forest structure, and climate on invasion success of non-native ambrosia beetles in deciduous temperate forests, and (2) to test the effect of host tree species on colonization success by non-native ambrosia beetles. In 2013, we sampled 25 forest stands located in North-East Italy belonging to three forest types dominated respectively by hop hornbeam, chestnut, and beech. Both ethanol-baited traps and trap-logs of five tree species (hop hornbeam, chestnut, beech, manna ash, and black locust) were used to sample non-native and native ambrosia beetle communities. We found a clear effect of forest composition on non-native species richness and activity-density, as measured in ethanol-baited traps, both of which were higher in chestnut-dominated forests. Furthermore, we found a positive effect of temperature on both the number of trapped non-native species and their activity-density, with cold temperatures limiting beetle spread in high-elevation forests. Only Xylosandrus germanus successfully colonized the trap-logs. The number of colonized logs was higher for chestnut and in chestnut-dominated forests. Both trapping and log-baiting indicated that chestnut-dominated forests were at greater risk of invasion than hop hornbeam- and beech-dominated forests. Given the economic and ecological importance of chestnut, ambrosia beetle communities present in chestnut-dominated forests should be monitored to determine where protective measures must be taken.     

Species diversity in North American temperate forests

Summary Samples from temperate forest communities across the North American continent were analysed for correlations of plant species diversity with environment and community structure.Alpha diversity relationships are complicated by different vegetation patterns and community history. The differences in community diversity patterns may be due to the independent evolution of communities in different regions.Results of analyses were: 1) on a continental scale plant species diversity is related to mean annual temperature, but not precipitation; 2) diversity is substantially greater in continental climates than in maritime regions; 3) diversity-community structure relationships are generally weak, except 4) there is an inverse relationship between diversity and abundance of conifer tree species. Attempts to relate diversity to environmental parameters with multiple regression techniques met with only moderate success.I thank R. H. Whittaker, R. K. Peet and H. G. Gauch, Jr., for their help and comments. I am especially grateful to R. H. Whittaker for making his data available to me. Computation was supported in part by N.S.F. grant No. GB-30679. I was supported by a Nat. Inst. of Health Traineeship during part of this study.     

Species coexistence in temperate, mixed deciduous forests

The response of tree life-history traits to community profiles (horizontal and vertical heterogeneity, disturbances and biotic interactions) determines community assembly rules, which are currently a hot issue in community ecology. Important mechanisms of coexistence differ throughout the developing stages of tree life history. Many processes of niche partitioning and tradeoffs that potentially enable tree coexistence have been reported to be present in temperate forests, although some of these life-history traits are either correlated with each other or are not independent. Not all of the proposed mechanisms explain coexistence equally well; some could predominate in determining the community organization of forest communities. Population studies need to concentrate more on the component species of a target community to detect the ecological assembly rule. These approaches can also address how chance factors contribute to the composition of temperate tree communities, which might be less dependent on chance than are tropical ones.     

Short-term development of ambrosia and bark beetle assemblages following a windstorm in French broadleaved temperate forests

Abstract: In most temperate deciduous forests, windstorm is the main source of dead wood. However, the effects of this natural disturbance on ambrosia and bark beetle communities are poorly known. In managed oak‐hornbeam forests storm‐damaged in France in 1999, we sampled ambrosia (and second bark beetles) by ethanol‐baited window‐flight traps in 2001. By comparing uncleared gaps, undisturbed closed‐canopy controls and seedling‐sapling stands, we investigated the short‐term effects of gap formation, gap size and surrounding landscape to provide a snapshot of scolytid response. Contrary to expectations, neither the abundance nor the richness of ambrosia beetle species was significantly higher in gaps than in undisturbed stands. Few responses in abundance at the species level and only a slight difference in assemblage composition were detected between gaps and closed‐canopy controls. Gaps were more dissimilar from seedling‐sapling stands, than from closed‐canopy controls. More scolytid individuals and species were caught in gaps than in seedling‐sapling stands. Mean local and cumulative richness peaked in mid‐size gaps. Only mid‐size gaps differed from closed‐canopy controls in terms of species composition. We identified generalist gap species (Xyleborus saxesenii, X. cryptographus), but also species significantly more abundant in mid‐size gaps (Platypus cylindrus, Xyloterus signatus). The faunistic peculiarity of mid‐size gaps seemed to be partly related to a bias in oak density among gap size classes. Few landscape effects were observed. Only the scolytids on the whole and X. dispar were slightly favoured by an increasing density in fellings at the 78 ha scale. We did not find any correlation between scolytid abundance and the surrounding closed‐forest percentage area. We confirmed that temperate, deciduous, managed stands did not come under threat by ambrosia and bark beetle pests after the 1999 windstorm. Nonetheless, our data stressed the current expansion in Western Europe of two invasive species, X. peregrinus and especially X. germanus, now the predominant scolytid in the three oak forests studied.     

Molecular phylogeny of bark and ambrosia beetles reveals multiple origins of fungus farming during periods of global warming

ABSTRACT: BACKGROUND: Fungus farming is an unusual life style in insects that has evolved many times in the wood boring weevils named 'ambrosia beetles'. Multiple occurrences of this behaviour allow for a detailed comparison of the different origins of fungus farming through time, its directionality, and possible ancestral states. We tested these hypotheses with a phylogeny representing the largest data set to date, nearly 4 kb of nucleotides from COI, EF-1alpha, CAD, ArgK, 28S, and 200 scolytine taxa. RESULTS: Phylogenetic analyses using Bayesian or parsimony approaches placed the root of Scolytinae close to the tribe Scolytini and Microborus, but otherwise indicated low resolution at older nodes. More recent clades were well resolved, including ten origins of fungus farming. There were no subsequent reversals to bark or phloem feeding in the fungus farming clades. The oldest origin of fungus farming was estimated near 50 Ma, long after the origin of Scolytinae (100-120 Ma). Younger origins included the species rich Xyleborini, dated to 21 Ma. Sister group comparisons and test of independence between traits indicated that neither gregarious larval feeding nor regular inbreeding by sibling mating was strongly correlated with the origin of fungus farming. CONCLUSION: Origins of fungus farming corresponded mainly with two periods of global warming in the Cenozoic era, which were characterised by broadly distributed tropical forests. Hence, it seems likely that warm climates and expanding tropical angiosperm forests played critical roles in the successful radiation of diverse fungus farming groups. However, further investigation will likely reveal additional biological factors that promote fungus farming.     

Two Ophiostoma species associated with bark beetles in wave-regenerated Abies veitchii forests in Japan

Two species of Ophiostoma were isolated from four bark beetles (i.e., Cryphalus montatus, C. piceae, Dryocoetes hectographus, and Polygraphus proximus) infesting Abies veitchii and from their galleries in the wave-regenerated forests in the central part of the main island (Honshu) of Japan. One of them is described here as a new species, Ophiostoma subalpinum, and the other is identified as O. davidsonii, newly reported in Japan. Ophiostoma subalpinum is characterized by short ostiolar hyphae, oblong or allantoid ascospores enclosed in a thin, hyaline sheath, and a Pesotum anamorph. Received: June 4, 2001 / Accepted: December 25, 2001     

DNA barcoding of bark and ambrosia beetles reveals excessive NUMTs and consistent east‐west divergence across Palearctic forests

A comprehensive DNA barcoding library is very useful for rapid identification and detection of invasive pest species. We tested the performance of species identification in the economically most damaging group of wood‐boring insects – the bark and ambrosia beetles – with particular focus on broad geographical sampling across the boreal Palearctic forests. Neighbour‐joining and Bayesian analyses of cytochrome oxidase I (COI) sequences from 151 species in 40 genera revealed high congruence between morphology‐based identification and sequence clusters. Inconsistencies with morphological identifications included the discovery of a likely cryptic Nearctic species of Dryocoetes autographus, the possible hybrid origin of shared mitochondrial haplotypes in Pityophthorus micrographus and P. pityographus, and a possible paraphyletic Xyleborinus saxeseni. The first record of Orthotomicus suturalis in North America was confirmed by DNA barcoding. The mitochondrial data also revealed consistent divergence across the Palearctic or Holarctic, confirmed in part by data from the large ribosomal subunit (28S). Some populations had considerable variation in the mitochondrial barcoding marker, but were invariant in the nuclear ribosomal marker. These findings must be viewed in light of the high number of nuclear insertions of mitochondrial DNA (NUMTs) detected in eight bark beetle species, suggesting the possible presence of additional cryptic NUMTs. The occurrence of paralogous COI copies, hybridization or cryptic speciation demands a stronger focus on data quality assessment in the construction of DNA barcoding databases.     

Host specificity of ambrosia and bark beetles (Col., Curculionidae: Scolytinae and Platypodinae) in a New Guinea rainforest

Abstract.  1. Bark and ambrosia beetles are crucial for woody biomass decomposition in tropical forests worldwide. Despite that, quantitative data on their host specificity are scarce.
2. Bark and ambrosia beetles (Scolytinae and Platypodinae) were reared from 13 species of tropical trees representing 11 families from all major lineages of dicotyledonous plants. Standardised samples of beetle-infested twigs, branches, trunks, and roots were taken from three individuals of each tree species growing in a lowland tropical rainforest in Papua New Guinea.
3. A total of 81 742 beetles from 74 species were reared, 67 of them identified. Local species richness of bark and ambrosia beetles was estimated at 80–92 species.
4. Ambrosia beetles were broad generalists as 95% of species did not show any preference for a particular host species or clade. Similarity of ambrosia beetle communities from different tree species was not correlated with phylogenetic distances between tree species. Similarity of ambrosia beetle communities from individual conspecific trees was not higher than that from heterospecific trees and different parts of the trees hosted similar ambrosia beetle communities, as only a few species preferred particular tree parts.
5. In contrast, phloeophagous bark beetles showed strict specificity to host plant genus or family. However, this guild was poor in species (12 species) and restricted to only three plant families (Moraceae, Myristicaceae, Sapindaceae).
6. Local diversity of both bark and ambrosia beetles is not driven by the local diversity of trees in tropical forests, since ambrosia beetles display no host specificity and bark beetles are species poor and restricted to a few plant families.     

Attraction of ambrosia and bark beetles to coast live oaks infected by Phytophthora ramorum

1 Sudden oak death is caused by the apparently introduced oomycete, Phytophthora ramorum. We investigated the role of bark and ambrosia beetles in disease progression in coast live oaks Quercus agrifolia. 2 In two Marin County, California sites, 80 trees were inoculated in July 2002 with P. ramorum and 40 were wounded without inoculation. Half of the trees in each group were sprayed with the insecticide permethrin [cyclopropanecarboxylic acid, 3‐(2,2‐dichloroethenyl)‐2,2‐dimethyl‐(3‐phenoxyphenyl) methyl ester] to prevent ambrosia and bark beetle attacks, and then were sprayed twice per year thereafter. After each treatment, sticky traps were placed on only the permethrin‐treated trees. Beetles were collected periodically in 2003. 3 Inoculated trees accounted for 95% of all beetles trapped. The ambrosia beetles Monarthrum scutellare and Xyleborinus saxeseni and the western oak bark beetle Pseudopityophthorus pubipennis were the most abundant of the seven species trapped. 4 Permethrin treatment delayed initiation of beetle attacks and significantly reduced the mean number of attacks per tree. Beetles did not attack any wounded or noncankered inoculated trees. 5 Trees with larger cankers trapped more beetles early in the disease. Once permethrin lost effectiveness, the number of beetle entrance tunnels was a more reliable predictor of subsequent trap catch than was canker size. 6 Beetles were initially attracted to P. ramorum cankers in response to kairomones generated in the host‐pathogen interaction. After beetles attacked the permethrin‐treated trees, aggregation pheromones most probably were the principal factor in beetle colonization behaviour.     

Species diversity of longicorn beetles in humid warm-temperate forests: the impact of forest management practices on old-growth forest species in southwestern Japan

In the humid warm-temperate zone of southwestern Japan, old-growthforests have been seriously fragmented to small remnants due to traditionalagriculture and coppicing as well as recent rapid plantation with conifers.Assemblages of longicorn beetles (Coleoptera: Disteniidae and Cerambycidae) werecompared among old-growth forests, second-growth forests and conifer plantationsusing collision traps baited with chemical attractants. Species richness oflongicorn beetles was poorer in second-growth forests and conifer plantationsthan in old-growth forests. It was proved by multidimensional scaling(MDS) that the beetle assemblages of old-growth forests were distinct from thoseof conifer plantations, while those of second-growth forests were intermediatebetween them. Further analysis showed that a number of species, including manyPidonia spp., were specific to or closely associated withold-growth forests, and the results were largely supported by the indicatorvalue (IndVal) approach. It is likely that many of such old-growth forestspecies in the larval and pupal stages require large broad-leaved trees standingor fallen with thick bark. At the same time, the flower-visiting adults wouldplay an important role in pollinating various herbaceous and woody plants.Regional forest management for the conservation of insect biodiversity is alsodiscussed.     

Fungal pathogen and ethanol affect host selection and colonization success in ambrosia beetles

1. Ambrosia beetles exhibit broad host ranges but a narrow preference based on the condition of the host. Tissues infected by pathogens or containing ethanol can facilitate attacks by ambrosia beetles, although it still remains unclear how these factors interact.
2. The present study aimed to examine how (i) chestnut logs infected with the fungal pathogen Cryphonectria parasitica and treated with ethanol (i.e. baited with ethanol lure, soaked in ethanol or untreated) and (ii) hornbeam logs soaked in different ethanol concentrations (3–12.5%) affect host selection and colonization success of ambrosia beetles.
3. Ethanol‐soaked logs were more attractive to Anisandrus dispar than ethanol‐baited logs or untreated logs, although this difference was more evident in uninfected than infected logs. Increasing ethanol concentration in host tissues was differentially attractive to Xyleborinus saxesenii and Xylosandrus germanus. A nonlinear relationship was also documented between ethanol concentration and emergence of X. germanus adults.
4. Overall, the results obtained suggest that the presence of C. parasitica in chestnut logs can affect host selection in ambrosia beetles. In addition, the ethanol concentration in tree tissues affects host selection and colonization success, although the effect varies depending on the beetle species. This contrasting response could be a niche‐partitioning mechanism based on ethanol within host tissues.

     

Influence of global warming on forest coleopteran communities with special reference to ambrosia and bark beetles

Forest insect pests are one of the major disturbance factors in forest ecosystems and their outbreaks are expected to be more severe under the influence of global warming. Coleopterans are dominant among forest insects and their ecological functions include general detritivores, dead wood feeders, fungivores, herbivores, live wood feeders and predators. Ambrosia and bark beetles contribute to ecological succession of forests and, therefore, ecological functions of forests can be changed in response to their outbreaks. Mountain pine beetle (MPB) outbreaks are the most dramatic example of changes in the ecological functions of forest due to the outbreak of a forest insect pest altered by global warming. Composition of coleopteran species varies with latitude. However, composition of functional groups is consistent with latitude which indicates that resources available to beetles are consistent. In coleopteran communities, ambrosia and bark beetles can become dominant due to increases of dead or stressed trees due to the warming climate. This can also induce changes in the ecological functions of coleopterans, i.e. selective force to displace trees that have lower ecological fitness due to temperature increase. Therefore, recent increases in the density ambrosia and bark beetles offer a chance to study ecological processes in forests under the influence of global warming.     

小蠹虫对针叶类寄主树木的选择危害机制

小蠹虫对寄主植物的选择是一个非常复杂的过程,也是近年来小蠹虫生态学研究的一个热门话题。文章对国内外小蠹虫寄主搜寻、寄主识别,以及适宜寄主选择等机制等方面的最新研究成果进行了系统报道。     

The evolution of mating systems in bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae)

The extraordinary array of mating systems in the Scolytidae and Platypodidae has been largely overlooked by researchers interested in the evolution of sexual behaviour. This paper provides the first overview of reproductive behaviour in this important and widespread group, known to most biologists only by the reputations of tree-killing taxa. Referred to generally as ‘bark beetles’, these insects chew egg tunnels inside a variety of (usually dead) plant tissues, though most species are either phloeophagous (breeding in the inner bark of woody plants) or xylomycetophagous (all stages feeding on mutualistic fungi growing on sapwood or heartwood). In most species, permanent records of many aspects of reproductive behaviour are etched in the host; in many, engravings reveal female fecundity, eggs sired per male, hatching success, and offspring survivorship. Each gallery arm represents a good portion of a given female's lifetime reproduction, but in many species females commonly re-emerge to reproduce in one or two additional sites. In most species of bark beetles, each female initiates her own gallery, to be joined later by a male. These monogynous gallery systems are associated with mating systems defined by how long males stay with females: in a few species, males seldom if ever join females under the bark; in the vast majority of species, males stay for part or all of the oviposition period then leave to seek other mates; and a few groups exhibit permanent monogamy, in that both sexes die in their only gallery system. While these patterns emerge from an overview of the world scolytid fauna, the length of male residency has seldom been quantified, and the costs and benefits associated with male mating strategies have not been measured for any bark beetle. Male-initiated monogyny is uncommon in Scolytidae, though the rule in Platypodidae; all instances of which I am aware are summarized from a phylogenetic perspective. Inbreeding polygyny with highly biased sex ratios has arisen at least seven times in Scolytidae. These taxa are usually characterized by males being dwarfed, flightless, and uncommon. Sex determination is known for only a few examples, but both haplodiploidy and diplodiploidy have been reported. Multiple origins of harem polygyny (otherwise rare in invertebrates) add an exciting dimension to the comparative and experimental study of scolytid mating systems. In harem polygynous taxa, males initiate gallery construction. I summarize what little can be learned from the literature about the fine structure of harem polygynous mating systems in bark beetles, and the problem of measuring reproductive success. Data on the nature of harem polygyny in Pityophthorus lautus are presented, illustrating (a) the fluidity of harems; (b) that average eggs laid per gallery arm is relatively unaffected by harem size, but strongly influenced by resource quality; (c) that male egg-gain is strongly correlated with territory quality (a consequence of (b) above); and (d) the temporal patterning of immigration and emigration and its effects on gallery system sex ratios. The second half of this paper is a discussion of the evolution of bark and ambrosia beetle mating Mating systems, emphasizing sexual selection and the role of resources. Male, residence is interpreted as postcopulalory guarding—preventing sexual liaisons with wandering males. Operational sex ratio, encounter rate, synchrony of breeding, ejaculate competition, and spatiotemporal distribution of resources are discussed as evolutionary forces moulding scolytid and platypodid male postmating behaviour. The nature of male male competition is reviewed. The paucity of information on male behaviour in gallery systems is mentioned; whether or not males significantly aid females is not known. Three hypotheses are presented for why females re-emerge, a feature which strongly affects operational sex ratios. Finally, I summarize features of bark beetle existence predisposing them to the evolution of post-inseminative guarding. Male-initiated monogyny presents a puzzle. I propose that most uncontested examples can be explained by monogyny re-evolving from (male-initiated) harem polygyny, and I present an argument for the evolution of harem polygyny leading to the development of male gallery initiation. The evolution of harem polygyny in birds and mammals has attracted considerable attention. The Verner Willson Orians polygyny threshold model is discussed with respect to bark beetles in general and P. lautus in particular. Resource quality is a major factor in P. lautus harem dynamics: the cost to females of joining harems is apparently slight compared to benefits accrued from moving into sites with higher quality inner bark. Female-biased adult sex ratios have been suggested to lead to harem polygyny, and literature and original data pertinent to this hypothesis are examined. The geometric constraints model, based on the polygyny threshold concept but tailored to bark beetles, is proposed to account for the failure of most species to evolve harem polygyny, and testable predictions are derived that interrelate breeding systems, habitat quality, and progeny size. The evolution of Inbreeding is briefly covered, and two routes to inbreeding polygyny are suggested.     

Plant species diversity in abandoned coppice forests in a temperate deciduous forest area of central Japan

We investigated plant species diversity as it related to stand structure and landscape parameters in abandoned coppice forests in a temperate, deciduous forest area of central Japan, where Fagus crenata was originally dominant. The species occurring in the study plots were classified into habitat types based on a statistical analysis of their occurrence bias in particular habitats (e.g., primary forest, coniferous plantation) in the landscape studied. The relationships between stand structure, which reflected the gradient of management, and forest floor plant species diversity (H and J) and richness (number of species per unit area) were not significant. However, these factors did influence the forest floor plant composition of the different types of habitat. According to the multiple regression analysis, species diversity and the richness of forest floor plants was affected by landscape parameters rather than by stand structure. For trees, species richness was mainly affected by the relative dominance of F. crenata, which is one of the stand structure parameters that decreases with intensive management. This is probably because many of the tree species that are characteristic of coppice forests increase after F. crenata have been eliminated by management; these species are not dominant in the original forest, where they are suppressed by F. crenata, the shade-tolerant dominant species. The species diversity (H and J) of trees was positively correlated with some landscape parameters, including the road density around the study plot, which may be associated with the intensity of management activity. The number of disturbance-tolerant species increased with increasing road density. Stand structure mainly affected disturbance-intolerant forest floor plant species and disturbance-tolerant tree species. Thus, the species diversity responses differed between forest floor plants and trees. The impact of forest management on species diversity was more prominent for forest floor plants.     

Species diversity and community structure of rove beetles (Coleoptera: Staphylinidae) attracted to dung of sika deer in coniferous forests of southwest Japan

Insect communities of mammal dung have been known as excellent model ecosystems for scientific study. Ecological surveys of diversity and seasonal patterns of coprophilous rove beetles in relation to wild mammals have rarely been conducted, although the high potential species diversity and abundance of the rove beetles are known. In order to investigate biodiversity of these beetles, we analyzed species composition, abundance, feeding guild and seasonality of rove beetles that were attracted to sika deer Cervus nippon dung by using dung‐baited pitfall traps for a 1.5‐year study in two plantations (cypress, cedar) and one secondary natural forest (pine) in Fukuoka Prefecture, southwest Japan. Consequently, saprophagous Anotylus sp. (Oxytelinae) was dominant in all forests. Analyses of feeding guild structure showed the number of individuals were dominated by saprophagous beetles, but the number of species were dominated by predatory beetles. Seasonal effects suggested that the species richness and abundance of rove beetles are possibly regulated by scarabaeoid dung beetles. These findings feature one example of a coprophilous rove beetle community.     

Cryptic diversity,high host specificity and reproductive synchronization in army ant‐associated Vatesus beetles

Army ants and their arthropod symbionts represent one of the most species‐rich animal associations on Earth, and constitute a fascinating example of diverse host–symbiont interaction networks. However, despite decades of research, our knowledge of army ant symbionts remains fragmentary due to taxonomic ambiguity and the inability to study army ants in the laboratory. Here, we present an integrative approach that allows us to reliably determine species boundaries, assess biodiversity, match different developmental stages and sexes, and to study the life cycles of army ant symbionts. This approach is based on a combination of community sampling, DNA barcoding, morphology and physiology. As a test case, we applied this approach to the staphylinid beetle genus Vatesus and its different Eciton army ant host species at La Selva Biological Station, Costa Rica. DNA barcoding led to the discovery of cryptic biodiversity and, in combination with extensive community sampling, revealed strict host partitioning with no overlap in host range. Using DNA barcoding, we were also able to match the larval stages of all focal Vatesus species. In combination with studies of female reproductive physiology, this allowed us to reconstruct almost the complete life cycles of the different beetle species. We show that Vatesus beetles are highly adapted to the symbiosis with army ants, in that their reproduction and larval development are synchronized with the stereotypical reproductive and behavioural cycles of their host colonies. Our approach can now be used to study army ant‐symbiont communities more broadly, and to obtain novel insights into co‐evolutionary and ecological dynamics in species‐rich host–symbiont systems.