Ant Crematogaster Research Articles

Ants as bioaccumulators of metals from soils: Body content and tissue-specific distribution of metals in the ant Crematogaster scutellaris

Ants possess several features that make them good candidates as indicators of environmental contamination. Concentrations of six metals (Cu, Cd, Ni, Mn, Pb and Zn) were investigated in Crematogaster scutellaris, a myrmicine ant common throughout the Mediterranean basin. Concentrations of metals in ant bodies and soil samples from polluted and unpolluted sites were compared. Tissue-specific distribution of metals in a non-soluble form was examined using a novel technique that coupled histological imagery and micro-PIXE analysis. Zinc and cadmium accumulated in ants with respect to the soil. Copper body burdens were independent of soil concentration, while lower concentrations of nickel, manganese and lead were found in ants than in the soil, although ant body content was correlated with soil concentrations. Most of the metals were concentrated in the midgut, the Malpighian tubules and fat body, supporting the role of these organs as primary sites of metal storage and contaminant immobilization.

PolydomousCrematogaster pilosa(Hymenoptera: Formicidae) Colonies Prefer Highly Connected Habitats in a Tidal Salt Marsh

High productivity in salt marshes creates an attractive resource base for terrestrial consumers, but regular tidal inundation creates a harsh environment. numerous terrestrial organisms have adapted to living in salt marshes by timing activity cycles and vertical movements to tidal cycles, while others exhibit physiological adaptations, increasing their tolerance to submersion (Foster 1983; Vaughn & Fisher 1992; petillon et al. 2009). one of the species able to withstand these harsh conditions is the ant Crematogaster pilosa (emery) (Hymenoptera: Formicidae), which has been reported to nest in hollow stems of salt marsh vegetation ranging from Florida to north carolina (davis & gray 1966; mccoy & rey 1987), as well as in trees in mesic forests and within stems of upland plants (teal 1962; Johnson 1988; morgan 2010). little is known about C. pilosa (synonymous with C. clara; Johnson 1988) with the exception of its flexible habitat requirements. the objective of this study was to examine the basic colony attributes and habitat preferences of C. pilosa in a saltmarsh cordgrass [Spartina alterniflora loisel (poales: poaceae)] dominated salt marsh on sapelo island, georgia. connectivity in the S. alterniflora canopy, dead and living stem densities, and maximum stem height were evaluated to examine the influence of habitat structure on ant densities. in october 2011, two marsh transects stretching from the forest edge to the bank of a large tidal creek were demarcated and divided into fourteen 10 × 2 m sections. ant density was sampled in 4 randomly selected 2 m2 quadrats per section by sweep netting for 15 seconds. percent vegetation cover was estimated from photographs taken from ground level and converted to binary sky/ vegetation images using imageJ software. living and dead stem density and tallest stem height were measured in 4 haphazardly placed quadrats (0.25 m2) within a subset of 9 sections. Workers from 15 nests were enumerated, and the presence of eggs or pupae was recorded. to evaluate tidal inundation relative to nest height, 5 fence posts with cups attached at 5 cm intervals covering the lower range of observed nest heights were deployed. Flooded cups were recorded daily for 4 days, which included some of the highest local tides of 2011. the spatial extent and number of colonies examined in this study are small, limiting the potential for generalization to other colonies and habitats. square-root transformed ant densities showed a positive correlation with percent vegetation cover (Fig. 1) when data were averaged over 20 m2 transect sections (r2 = 0.50, p = 0.003). no relationship was found between ant density and living stem density (r2 = 0.21, p = 0.22), dead stem density (r2 = 0.06, p = 0.53), or tallest stem height (r2 = 0.10, p = 0.42). mean nesting stem and entrance heights were 44.6 cm (sd = 14.4) and 35.3 cm (sd = 10.6), respectively. the maximum observed tidal height from substrate was less than 20 cm, and minimum nest entrance height was 21 cm (Fig. 2). nests averaged 242 workers (range: 53-1106, sd = 276), which is conservative because some workers were foraging at the time of collection. eggs and pupae were found in 87% and 46% of the nests, respectively. Workers were observed traveling and carrying eggs among 21 nests within

Thorn‐dwelling ants provide antiherbivore defence for camelthorn trees, Vachellia erioloba, in Namibia

AbstractAnts are widely employed by plants as an antiherbivore defence. A single host plant can associate with multiple, symbiotic ant species, although usually only a single ant species at a time. Different plant‐ant species may vary in the degree to which they defend their host plant. In Kenya, ant–acacia interactions are well studied, but less is known about systems elsewhere in Africa. A southern African species, Vachellia erioloba, is occupied by thorn‐dwelling ants from three different genera. Unusually, multiple colonies of all these ants simultaneously and stably inhabit trees. We investigated if the ants on V. erioloba (i) deter insect herbivores; (ii) differ in their effectiveness depending on the identity of the herbivore; and (iii) protect the tree against an important herbivore, the larvae of the lepidopteran Gonometa postica. We show that experimental exclusion of ants leads to greater levels of herbivory on trees. The ants inhabiting V. erioloba are an effective deterrent against hemipteran and coleopteran, but not lepidopteran herbivores. Defensive services do not vary among ant species, but only Crematogaster ants exhibit aggression towards G. postica. This highlights the potential of the V. erioloba–ant mutualism for studying ant–plant interactions that involve multiple, simultaneously resident thorn‐dwelling ant species.

Seasonal Abundance of Hemipterans onCaryocar brasiliense(Malpighiales: Caryocaraceae) Trees in the Cerrado

Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) trees have a wide distribution in the cerrado. This plant is protected by federal laws and is untouched in deforested areas of the cerrado. Under these circumstances, the damage to leaves, flowers, and fruits from sucking hemipterans has increased. We studied populations of sucking insects and their predators on C. brasiliense trees in the cerrado during each season for 3 successive years. The numbers of sucking insect individuals on C. brasiliense trees were similar among the seasons of the year. However, the highest number of species and greatest diversity occurred in winter. Predators were most abundant in spring and winter, with highest diversity and number of species in winter. We observed 7 rare, 2 common, and 1 constant species of sucking insects; and 4 rare, 8 common, and 1 constant species of predators on C. brasiliense trees. The greatest numbers of various sucking insect species were observed by seasons as follows: Aconophora sp. (Membracidae) on fruits and Frequenamia sp. (Cicadellidae) on leaves in the winter; Aphis gossypii (Glover) (Aphididae) and Mahanarva sp. (Cercopidae) in the spring; and Dikrella sp. (Hemiptera: Cicadellidae) on the leaves in the summer and autumn. For predators, Crematogaster sp. (Hymenoptera: Formicidae) had the lowest abundance on the leaves in the summer, and highest abundance in the flowers in the winter and spring, while in spring it was most abundant on the fruits, and in the autumn Trybonia sp. (Thysanoptera: Phlaeothripidae) on the leaves was the most abundant. Higher number of ants Crematogaster sp. was observed in Caryocar brasiliense trees that presented large numbers of Dikrella sp.. Higher numbers of predators Trybonia sp., Chrysoperla sp. (Neuroptera: Chrysopidae), and total of predator thrips were associated with decreasing numbers of Dikrella sp., A. gossypii, and total of sucking insects respectively. The increase in the numbers of individuals and species of predators were correlated with the reduction of these same ecological parameters of the sucking insects. We argue that this differential temporal distribution of sucking insects and their predators was influenced for phenology of plant and weather.

A subgeneric revision of Crematogaster and discussion of regional species-groups (Hymenoptera: Formicidae)

Crematogaster ants are diverse, widespread and abundant in tropical, subtropical and warm-temperate climatesthroughout the world. The species diversity of this genus has been notoriously difficult to manage based upon morphologyalone, and former attempts have generated a vaguely defined subgeneric system. I propose an improvement of the previoussubgeneric classification and recognize two subgenera based upon a concurrent molecular study of the global diversity ofthese ants. Five of 13 former subgenera of Crematogaster are hereby synonymised under the subgenus OrthocremaSantschi: Neocrema Santschi syn. nov., Eucrema Santschi syn. nov., Rhachiocrema Mann syn. nov., Mesocrema Santschisyn. nov. and Apterocrema Wheeler syn. nov.. The eight remaining subgenera are synonymised under the subgenusCrematogaster sensu stricto: Decacrema Forel syn. nov., Oxygyne Forel syn. nov., Atopogyne Forel syn. nov.,Sphaerocrema Santschi syn. nov., Colobocrema Wheeler syn. nov., Paracrema Santschi syn. nov., Physocrema Forelsyn. nov. and Xiphocrema Forel syn. nov.. I present keys, morphological diagnoses and illustrations for the two revised,globally distributed subgenera Orthocrema and Crematogaster sensu stricto, based upon the worker caste. The twosubgenera can be distinguished from each other by a combination of features of the petiole, postpetiole and propodealspiracle. I also provisionally circumscribe a number of species-groups within the subgenus Crematogaster and discuss the utility of species-groups for further taxonomic, phylogenetic and ecological research on the genus Crematogaster.

Estruturas secretoras em cipó-d'alho (Mansoa standleyi (Steyerm.) A. H. Gentry, Bignoniaceae): ocorrência e morfologia

Espécies de Mansoa são denominadas de "cipó-d'alho", por exalarem odor de alho das partes vegetativas e reprodutivas. Contudo, dados sobre morfologia e distribuição das estruturas secretoras presentes em Mansoa são escassos e ausentes para M. standleyi. O presente trabalho objetivou caracterizar a ocorrência e morfologia das estruturas secretoras do eixo vegetativo aéreo de M. standleyi. Para tanto, amostras da lâmina foliolar e de regiões nodais foram fixadas e submetidas às técnicas histológicas e de microscopia eletrônica de varredura. Testes histoquímicos, com os respectivos controles foram aplicados nas estruturas secretoras em fase secretora. Indivíduos de formigas e moscas, que visitavam a espécie foram amostrados, preservados e identificados por entomólogo. As estruturas secretoras do eixo vegetativo aéreo de M. standleyi estão representadas por tricomas glandulares dos tipos pateliformes e peltados. Todos com desenvolvimento assincrônico e presentes nas regiões nodais e lâmina foliolar, principalmente nas partes mais jovens. Nas regiões nodais, os tricomas formam um complexo secretor e, na lâmina foliolar, estão dispersos. As análises histoquímicas revelaram que os tricomas pateliformes são de fato nectários extraflorais e que os tricomas peltados, apresentam uma fração de alcaloides. Os visitantes das glândulas nodais correspondem a formigas Crematogaster (Formicidae) e Ectatomma brunea (Vespoidea, Formicidae) e moscas Oxysarcodexia (Sarcophagidae, subfamília Utitidae (Ulidiidae). Mansoa standleyi possui as estruturas secretoras do eixo vegetativo aéreo semelhantes às citadas pela literatura para Bignoniaceae, sendo esta a primeira vez, que um nectário extrafloral é descrito para a espécie.

Acrobat ants go global – Origin, evolution and systematics of the genus Crematogaster (Hymenoptera: Formicidae)

This study unravels the evolution and biogeographic history of the globally distributed ant genus Crematogaster on the basis of a molecular phylogeny, reconstructed from five nuclear protein-coding genes and a total of 3384bp of sequence data. A particular emphasis is placed on the evolutionary history of these ants in the Malagasy region. Bayesian and likelihood analyses performed on a dataset of 124 Crematogaster ingroup taxa lend strong support for three deeply diverging phylogenetic lineages within the genus: the Orthocrema clade, the Global Crematogaster clade and the Australo-Asian Crematogaster clade. The 15 previous subgenera within Crematogaster are mostly not monophyletic. Divergence dating analyses and ancestral range reconstructions suggest that Crematogaster evolved in South-East Asia in the mid-Eocene (40–45ma). The three major lineages also originated in this region in the late Oligocene/early Miocene (∼24–30ma). A first dispersal out of S-E Asia by an Orthocrema lineage is supported for 22–30ma to the Afrotropical region. Successive dispersal events out of S-E Asia began in the early, and continued throughout the late Miocene. The global distribution of Crematogaster was achieved by subsequent colonizations of all major biogeographic regions by the Orthocrema and the Global Crematogaster clade. Molecular dating estimates and ancestral range evolution are discussed in the light of palaeogeographic changes in the S-E Asian region and an evolving ocean circulation system throughout the Eocene, Oligocene and Miocene. Eight dispersal events to/from Madagascar by Crematogaster are supported, with most events occurring in the late Miocene to Pliocene (5.0–9.5ma). These results suggest that Crematogaster ants possess exceptional dispersal and colonization abilities, and emphasize the need for detailed investigations of traits that have contributed to the global evolutionary success of these ants.

Small Size No Protection for Acrobat Ants: World's Smallest Fly is a Parasitic Phorid (Diptera: Phoridae)

Abstract A new species of phorid fly, Euryplatea nanaknihali (Diptera: Phoridae), is described from Thailand. This is the first Oriental Region record for this genus; it is otherwise known only from the type species from Africa, where it parasitizes ants of the genus Crematogaster Lund. The new species is probably capable of parasitizing the smallest host Crematogaster (Formicidae) ants in its range. At 0.40 mm in body length, it is the smallest known fly in the world.

Timing of butterfly parasitization of a plant–ant–scale symbiosis

In the Southeast Asian tropics, Arhopala lycaenid butterflies feed on Macaranga ant-plants inhabited by Crematogaster (subgenus Decacrema) ants tending Coccus-scale insects. A recent phylogenetic study showed that (1) the plants and ants have been codiversifying for the past 20–16 million years (Myr), and that (2) the tripartite symbiosis was formed 9–7 Myr ago, when the scale insects became involved in the plant–ant mutualism. To determine when the lycaenids first parasitized the Macaranga tripartite symbiosis, we constructed a molecular phylogeny of the lycaenids that feed on Macaranga by using mitochondrial and nuclear DNA sequence data and estimated their divergence times based on the cytochrome oxidase I molecular clock. The minimum age of the lycaenids was estimated by the time-calibrated phylogeny to be 2.05 Myr, about one-tenth the age of the plant–ant association, suggesting that the lycaenids are latecomers that associated themselves with the pre-existing symbiosis of plant, ant, and scale insects.

Multicoloniality in the highly polygynous ant Crematogaster pygmaea (Formicidae: Myrmicinae)

In social insects, the high variability in the number of queens per colony raises fundamental questions about the evolution of altruism. It is hypothesized, for instance, that nestmate recognition should be less efficient in polygynous than in monogynous colonies because the presence of several breeders increases the diversity of genetically determined recognition cues, leading to a less specific colonial signature. Recent studies, however, have shown that the link between the number of queens in a colony and the recognition abilities of its members is more complex than previously suggested. Here, we studied intraspecific aggression, diversity of potential recognition cues and genetic structure of colonies in the highly polygynous ant Crematogaster pygmaea. Our results reveal that workers of this species are clearly aggressive towards non-nestmates in field experiments but not in more artificial bioassays conducted in Petri dishes, underscoring the importance of context-dependent aspects of the assessment of nestmate recognition. Behavioural, genetic and chemical data show that C. pygmaea is a multicolonial species, forming spatially restricted and well-defined entities. Therefore, the postulated negative correlation between recognition ability of workers and queen number in a colony is not supported by the results of this study.

Antibacterial properties of contact defensive secretions in neotropical Crematogaster ants

Crematogaster ants use their contact venoms to compete with other ants. Although those venoms are used primarily as repellent and toxic secretions, they may have other functions. The present study aimed to test the antibacterial property of abdominal venom of three neotropical Crematogaster ant species (C. distans, C. pygmaea and C. rochai) against gram-negative (Escherichia coli and Pseudomonas aeruginosa) and gram-positive (Enterococcus faecalis and Staphylococcus aureus) bacteria. Sterile filter paper was soaked with C. distans, C. pygmaea or C. rochai crude venom and placed on an agar dish that was inoculated with bacterial suspensions. The agar dish was incubated overnight at 37ºC and examined for zones of growth inhibition. For each tested venom and bacterial strain, three venom concentrations were used, with six replicates for each concentration: 1, 2 and 4 DGE (Dufour's gland equivalent). The venom of C. pygmaea, but not those of C. rochai and C. distans, inhibited the growth of all tested gram-positive and gram-negative bacterial strains. This is the first evidence of antibacterial properties of contact venoms in Crematogaster ants and it supports the claim that ant venoms are multifunctional. It is hypothesized that only C. pygmaea venom showed antibacterial activities due to its nesting habits.

Paralyzing action from a distance in an arboreal African ant species.

Due to their prowess in interspecific competition and ability to catch a wide range of arthropod prey (mostly termites with which they are engaged in an evolutionary arms race), ants are recognized as a good model for studying the chemicals involved in defensive and predatory behaviors. Ants' wide diversity of nesting habits and relationships with plants and prey types implies that these chemicals are also very diverse. Using the African myrmicine ant Crematogaster striatula as our focal species, we adopted a three-pronged research approach. We studied the aggressive and predatory behaviors of the ant workers, conducted bioassays on the effect of their Dufour gland contents on termites, and analyzed these contents. (1) The workers defend themselves or eliminate termites by orienting their abdominal tip toward the opponent, stinger protruded. The chemicals emitted, apparently volatile, trigger the recruitment of nestmates situated in the vicinity and act without the stinger having to come into direct contact with the opponent. Whereas alien ants competing with C. striatula for sugary food sources are repelled by this behavior and retreat further and further away, termites defend their nest whatever the danger. They face down C. striatula workers and end up by rolling onto their backs, their legs batting the air. (2) The bioassays showed that the toxicity of the Dufour gland contents acts in a time-dependent manner, leading to the irreversible paralysis, and, ultimately, death of the termites. (3) Gas chromatography-mass spectrometry analyses showed that the Dufour gland contains a mixture of mono- or polyunsaturated long-chain derivatives, bearing functional groups like oxo-alcohols or oxo-acetates. Electrospray ionization-mass spectrometry showed the presence of a molecule of 1584 Da that might be a large, acetylated alkaloid capable of splitting into smaller molecules that could be responsible for the final degree of venom toxicity.

Spatial patterns of the ant Crematogaster scutellaris in a model ecosystem

1. The spatial arrangement of individuals and populations may have deep influences on all the biotic interactions within a community.2. The spatial distribution of nests of the ant Crematogaster scutellaris Olivier was analysed in an olive orchard in central Italy. As this species nests inside tree trunks, the regular structure of this simplified ecosystem may help to reduce the confounding effect of habitat heterogeneity on the spatial distribution of nests. In total, 531 trees were mapped and their shape (size and structure of the trunk) recorded. The presence of C. scutellaris nests in each tree was assessed in spring–summer and autumn 2006 and 2007.3. The number of occupied trees changed in time, from a maximum of 129 (summer 2006) to a minimum of 60 (autumn 2007). Occupancy of tree was related to its shape, with larger trees being more frequently and more steadily occupied than smaller ones.4. Nests were spatially aggregated, forming well‐defined clusters, but aggregation was not explained by a corresponding clumping of larger trees. Nests belonging to the same cluster were usually not aggressive to each other, whereas aggression was more common between nests belonging to different clusters. The dynamic nature of the system coupled with the clustered distribution of nests, is consistent with a hypothesis of seasonal polydomy, and suggest that whereas some trees are steadily occupied (core) others are opportunistically colonised when new resources are discovered (satellites).5. Clusters size distribution was shown to follow a truncated power‐law, a finding consistent with the idea that clusters are self‐organised structures dependent on local interactions. These results suggest that spatial self‐organisation in ant colonies may in principle be more common than previously thought, although the mechanisms generating these patterns still need to be clarified.

Preference of foraging ants (Hymenoptera: Formicidae) for bait toxicants in South African vineyards

Argentine ants Linepithema humile (Mayr), common pugnacious ants Anoplolepis custodiens (F. Smith) and cocktail ants Crematogaster peringueyi Emery are the main indirect ant pests in South African vineyards. These ants form mutualistic relationships with the vine mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), an economic phloem-feeding pest of vines that excretes honeydew. Ants feed on the honeydew from mealybugs and also affect predator–prey interactions by protecting them from attack by natural enemies. This consequently reduces the efficacy of predators and parasitic Hymenoptera in controlling P. ficus. Current strategies for ant control are limited to the application of long term residual insecticides that are detrimental to the environment, labour intensive to apply and potentially disruptive to biological control. Here, we report on the development of an alternative method of ant control using baits which are likely to show delayed toxicity to these ant species. Field bait preference assessments were carried out during spring, summer and autumn in three vineyards of the Cape Winelands region, Republic of South Africa during 2007/08. Preference/non-preference is the first behaviour an ant exhibits when encountering bait and this was measured in terms of numbers of ants at bait stations. Five toxicants comprising Gourmet ant bait (containing 0.5% boric acid as active ingredient and a honeydew mimic as an attractant), boric acid (0.5%), fipronil (0.0001%), fenoxycarb (0.5%) and spinosad (0.01%) all dissolved in 25% sucrose solution were tested against a 25% sucrose solution control. Gourmet ant bait was overall the most preferred bait during spring, summer and autumn, and on some occasions being significantly more preferable to ants than the control solution.

Successional patterns of the insect fauna on a pig carcass in southern Italy and the role of Crematogaster scutellaris (Hymenoptera, Formicidae) as a carrion invader

AbstractThe sarcosaprophagous fauna plays a key role in organic matter decomposition. Moreover, the biological, ecological and behavioral specificities of the taxa are useful to reconstruct the decay history of a corpse or carcass, often back to the lethal event. Here we report the seasonal succession of the insect fauna on a pig carcass exposed in a rural area in Calabria (southern Italy) during summer 2007 and 2008. The aim is to identify and qualitatively assess the major taxa of forensic importance in this region. The principal fly invaders were Lucilia caesar (L.), L. sericata (Meigen, 1826), Chrysomya albiceps (Wiedemann, 1819), Sarcophaga (Meigen, 1826) spp. and Amobia (Robineau‐Desvoidy, 1830) spp., Musca domestica (L.) and Muscina stabulans (Fallen, 1817). The primary beetle species collected in summer belonged to Dermestidae, Dermestes maculatus (De Geer, 1774) and Cleridae, Necrobia rufipes (De Geer, 1775). This paper also examined the ecological role of ants in the insect succession and describes the evidence of skin injuries directly inflicted by the acrobat ant Crematogaster (Acrocoelia) scutellaris (Olivier, 1791) (Hymenoptera Formicidae) while feeding on pig carrion. Ants belonging to two other species were also collected: Camponotus aethiops (Latreille, 1798) and Tetramorium semilaeve (André, 1881). Ants can invade carcasses and corpses directly, disrupting blowfly egg laying or preying on their larvae. Our data on the carrion faunal composition and role of ants as invaders should be useful for further forensic cases in Calabria (southern Italy). This is among the few reports of ants as forensically relevant species.

A Myrmecophilous Mite Myrmozercon Tauricus Sp. N. of the Family Laelapidae (Acari, Mesostigmata) from Ukraine

A Myrmecophilous Mite Myrmozercon Tauricus Sp. N. of the Family Laelapidae (Acari, Mesostigmata) from Ukraine A laelapid mite Myrmozercon tauricus Trach et Khaustov, sp. n. collected from nests of ants Crematogaster schmidti (Mayr, 1853) (Hymenoptera: Formicidae) in Crimea (Ukraine) is described. The genus Myrmozercon Berlese, 1902 is recorded in Ukraine for the first time.

The function of polydomy: the ant Crematogaster torosa preferentially forms new nests near food sources and fortifies outstations

Many ant species are polydomous, forming multiple spatially segregated nests that exchange workers and brood. However, why polydomy occurs is still uncertain. We investigated whether colonies of Crematogaster torosa form new polydomous nests to better exploit temporally stable food resources. Specifically, we tested the effect of food presence or absence and distance on the likelihood that colonies would form a new nest. Because this species also forms little-known structures that house only workers without brood (outstations), we also compared the function of this structure with true nests. Laboratory-reared colonies were connected to a new foraging arena containing potential nest sites with or without food for 4 months. When food was present, most colonies formed polydomous nests nearby and the remainder formed outstations. When food was absent, the behavior of colonies differed significantly, frequently forming outstations but never polydomous nests. Distance had no effect on the type of structure formed, but when food was present, a larger proportion of the workforce moved shorter distances. Workers often fortified the entrances to both structures and used them for storage of dried insect tissue (“jerky”). In an investigation of spatial fidelity, we found that workers on the between-nest trail were associated with the original nest, whereas workers collecting food were more likely to be associated with the new nest or outstation. C. torosa appears to have a flexible colony structure, forming both outstations and polydomous nests. Polydomous nests in this species were associated with foraging and were only formed near food resources.

ChemInform Abstract: A Novel Synthesis of (S)-6-Methyl-3-octanone, the Alarm Pheromone of Crematogaster Ants.

ChemInform Abstract: A Novel Synthesis of (S)-6-Methyl-3-octanone, the Alarm Pheromone of Crematogaster Ants.

New data of the genus Crematogaster Lund, 1831 (Hymenoptera: Formicidae) in Crna Gora (Montenegro), Part I: Crematogaster scutellaris group of species

1* Summary Taxonomy, morphology and the geographic distribution of four species of the Crematogaster scutellaris group of species, ant genus Crematogaster, in Crna Gora (Montenegro) are presented. Specimens were collected from various localities in Montenegro during the period 1977-2008. The synonymy, distribution, number of collected specimens and the collector are given for each species. Morphology of genitalia of Crematogaster gordani Karaman, 2008, and new information related to the discrimination of males of two sibling species, C. gordani and Crematogaster schmidti (Mayr 1853) are given.

Estimation of dispersal distances of the obligately plant-associated ant Crematogaster decamera

1. In obligate symbioses with horizontal transmission, the population dynamics of the partner organisms are highly interdependent. Host population size limits symbiont number, and distribution of partners is restricted by the presence and thus dispersal abilities of their respective partner. The Crematogaster decamera–Macaranga hypoleuca ant–plant symbiosis is obligate for both partners. Host survival depends on colonisation by its ant partner while foundress queens require hosts for colony establishment. 2. An experimental approach and population genetic analyses were combined to estimate dispersal distances of foundresses in their natural habitat in a Bornean primary rainforest. 3. Colonisation frequency was significantly negatively correlated with distance to potential reproductive colonies. Results were similar for seedlings at natural densities as well as for seedlings brought out in the area experimentally. Population genetic analysis revealed significant population differentiation with an FST of 0.041 among foundresses (n = 157) located at maximum 2280 m apart. In genetic spatial autocorrelation, genotypes of foundresses were significantly more similar than expected at random below 550 m and less similar above 620 m. Direct estimation of dispersal distances by pedigree analysis yielded an average dispersal distance of 468 m (maximum 1103 m). 4. For ants that disperse on the wing, genetic differentiation at such small spatial scales is unusual. The specific nesting requirements of the queens and the necessity for queens to find a host quickly could lead to colonisation of the first suitable seedling encountered, promoting short dispersal distances. Nonetheless, dispersal distances of C. decamera queens may vary with habitat or host spatial distribution.