Structure of multi-species ant assemblages (Hymenoptera,Formicidae) in the Mountain Crimea

The multi-species ant assemblages were studied in the Crimea Mountains, in 9 types of plant associations in the plateau pastures as well as on the southern and northern slopes of the Main Range. A list of 18 ant species with data on their distribution in biotopes and also layers and the structure of their foraging territories is given. The hierarchical organization of multi-species ant assemblages and different strategies of nest location of the influents depending on the dominant species and its territoriality were investigated. Territoriality of each dominant species was determined by the frequency of foraging areas without nests of other species. Depending on dominant territoriality and the number of dominant species, the following classification of multi-species assemblages is proposed. (1) Monodominant assemblages with weakly expressed territoriality of the dominant species. Low density of the workers of Camponotus aethiops in the foraging territory determines weak interactions with influent species. The settling pattern of the influents shows no evident dependence on the dominant. Weakly expressed territoriality of the dominant allows non-territorial species to exist on the dominant’s territory. Such species were not found in other types of ant assemblages. (2) Monodominant assemblages with strongly expressed territoriality of the dominant species. The settling pattern of the influents shows the subordinate species to avoid those of higher ranks in the hierarchy, thus decreasing the probability of conflicts. The influents settle in the neutral zones as well as in the foraging territory of the dominant, so as to reduce competition with the subdominant species Formica cunicularia. Such a strategy reduces the probability of interspecific conflicts in biotopes with fewer vegetation layers than in the forests. (3) Bidominant assemblages with a variable dendrobiont dominant are typical among forest assemblages. Coexistence of two dominant species is possible when foraging of one of them is completely or partly restricted to one vegetation layer. The subdominant species avoid settling in the foraging territory of the dominant that occupies the same layer. When the dendrobiont dominant Crematogaster schmidti drops out of the assemblage, it (and its role in the assemblage) is replaced by other dendrobiont species Lasius emarginatus which otherwise acts as the 1st order subdominant in C. schmidti assemblages. (4) Polydominant assemblages are characterized by the presence of as many as 3 dominant species, namely Crematogaster schmidti, Camponotus aethiops, and Plagiolepis tauricus. The coexistence of the dominants is possible due to use of different layers (one species is a dendrobiont, the other two are herpeto-hortobionts), different activity periods (round-the-clock in Crematogaster schmidti, night in Camponotus aethiops, and daytime in P. tauricus), and different size classes of the workers (3rd, 5th, and 1st, respectively). The different size classes of workers reduce competition for food. Thus, when the number of dominant species in the assemblage increases, so does the number of mechanisms facilitating their coexistence.     

<Emphasis Type="Italic">Crematogaster subdentata</Emphasis> Mayr, 1877, a potentially invasive species of ant (Hymenoptera,Formicidae) new to the fauna of crimea

A population of a new to Crimea and potentially invasive ant species, Crematogaster subdentata Mayr, 1877, has been found in Mikhailovka Village of Saki District (the Crimean Peninsula). The species may have been introduced to Crimea from Central Asia. The study addresses the ecology and behavior of C. subdentata that inhabits the newly invaded region, including the time-dependent density of its colonies, the structure of foraging areas, the daily activity cycle, and control measures. The invasion began 9–12 years ago. There are 4 settlements discovered that differ in their age and the structure of the foraging area. C. subdentata can be considered a potentially dangerous invader that is capable of doing significant damage to the biocenoses of forests, parks, and gardens, as well as to wooden buildings.     

Stratification of the ant species (Hymenoptera,Formicidae) in the urban broadleaf woodlands of the city of Kiev

Investigations were carried out in June–August 2012 and 2013 in broadleaf forests and planted stands of the northern red oak Quercus rubra in Kiev. The ant visitation rates of 3–6 most abundant plant species within each vegetation layer were analyzed. In all, 16 species of ants were found in the broadleaf forest (Quercus robur + Acer spp. + Carpinus betulus), with the dominance of three species: Formica rufa, Lasius fuliginosus, and L. emarginatus. Eight ant species occurred in Q. rubra stands with the undergrowth of Acer campestre and A. platanoides; the dominant species were Lasius fuliginosus and L. emarginatus. The northern red oak stands with conspecific undergrowth had only four ant species with no dominants among them. Plants with the highest ant visitation rates in the herbage layer of the broadleaf forest were the invasive Impatiens parviflora and the native Aegopodium podagraria. Ants were rare or absent on the remaining herbs: Impatiens noli-tangere, Carex sylvatica, Stellaria holostea, and Galium odoratum. The herbage layer was mostly visited by influents, the dominants being represented only by Lasius emarginatus. Within the shrub layer, ants most frequently visited the undergrowth of the maple Acer platanoides, often harboring colonies of the aphid Periphyllus lyropictus; the highest visitation rates were recorded in the dominants L. emarginatus and L. fuliginosus. The arboreal layer had the highest visitation rate and was most often visited by the dominants Lasius fuliginosus, L. emarginatus, and F. rufa. The common oak Q. robur was the most visited tree in broadleaf forests. In addition to providing ants with food (colonies of the aphids Lachnus roboris and Stomaphis quercus, and also phytophagous insects and other invertebrates), these trees were used for nesting by the dominants L. fuliginosus and L. emarginatus. The presence of aphid colonies was also typical of ripe trees and undergrowth of the maple A. platanoides, the second-visited tree in broadleaf forests. The common hornbeam Carpinus betulus was the least frequently visited, though some ant species, usually L. emarginatus, nested in the trunks and branches of old trees. The vertical distribution of ants in broadleaf forests and red oak stands formed two clusters: the influents occupied the lower (herbage and shrub) vegetation layers, while the subdominants and dominants occupied the upper (shrub and arboreal) ones. The smallest number of ant species (1 or 2) in all the vegetation layers was recorded in the areas with F. rufa; areas with L. fuliginosus had twice as many species; the greatest numbers of ant species were found in the areas with L. emarginatus and in those without dominants. This pattern may result from different territoriality of the dominants: the strongest in F. rufa (defending the whole territory) and the weaker in the other two species (defending only a part of the territory). Plants of all the vegetation layers varied in their attractiveness to ants. As a result, the layers had a mosaic structure in their vertical (between-layer) and horizontal (between different plant species within one layer) arrangement. From 60 to 100% of plants of certain species were visited by ants while plants of other species were not visited at all. The main reason for visiting plants by ants was the presence of aphid colonies.     

Effect of Invasive Species of Herbaceous Plants and Associated Aphids (Hemiptera,Sternorrhyncha: Aphididae) on the Structure of Ant Assemblages (Hymenoptera,Formicidae)

—In 2015–2017, attendance of 15 invasive and 22 native species of herbaceous plants by ants was studied in 6 habitats in the environs of Kyiv (Ukraine). Altogether, 14 ant species were found, of which 12 were recorded on invasive plants and 9 on native plants; 8 aphid species were found on 8 invasive plant species. Five invasive plant species (Asclepias syriaca, Heracleum mantegazzianum, Oenothera biennis, Onopordum acanthium, and Amaranthus retroflexus) were found to be attractive to ants, with over a half of all the ant workers in all the habitats being recorded on them; besides, numerous colonies of 7 aphid species were also found on these plants. These invasive plants positively affect the structure of ant assemblages since the aphid colonies provide ants with food resource. The remaining 10 invasive plant species, including 5 transformer species, were poorly visited by ants and housed no aphid colonies, with the exception of Conyza canadensis on which the non-myrmecophilous aphid Uroleucon erigeronense (Thomas, 1878) was found. Two thirds of invasive plant species had a negative effect on the structure of ant assemblages because they replaced the native plants and thus reduced the trophic resources of aphids.

     

Ants (Hymenoptera,Formicidae) of Kyiv

Entomological Review - Altogether, 59 ant species from 22 genera of 4 subfamilies have been recorded in Kyiv. Four of them are occasionally introduced species which occur only in premises heated in...     

<Emphasis Type="Italic">Lasius neglectus</Emphasis> Van Loon et al. (Hymenoptera,Formicidae), an Invasive Ant Species in Crimea

Data on distribution of Lasius neglectus Van Loon et al. in Crimea are reported. The structure of foraging areas of 111 monocalic and polycalic colonies, the daily activity rhythm, and the visiting of 26 species of trees by L. neglectus workers were studied; over a third of the visited tree species were conifers. Most colonies of L. neglectus in Crimea are monocalic. No replacement of the 12 native ant species present in the territories of the monocalic and polycalic colonies of L. neglectus was observed. Invasion of L. neglectus to Crimea probably started in the early 1970s.     

The beginning of the invasion of <Emphasis Type="Italic">Lasius neglectus</Emphasis> (Hymenoptera,Formicidae) in Kiev (Ukraine)

Research conducted in August and September 2016 in the city of Kiev (Ukraine). A total of 8 places of the possible location of invasive garden ant Lasius neglectus Van Loon, Boomsma & Andrasfalvy, 1990 were observed. Only one monocalic colony of L. neglectus was discovered. The forage area of L. neglectus is bounded by asphalted area on three sides. We consider that the invasion of L. neglectus at an early stage can be successful under the following conditions: (a) Favorable temperature. Mitigating of the climate during the winter months in recent years contributed to the consolidation of L. neglectus in Kiev. (b) Spatial separation of nests and foraging trails of native dominant ant species. In our case, L. neglectus colony was found on the site free of other ants. (c) Visiting trees, where native ant species are few or absent. This one partially overlaps with the previous condition.     

The Effect of Climatic Factors on the Activity of Ants (Hymenoptera,Formicidae) in Broadleaf Forests of Kiev. Communication 2

Studies of seasonal dynamics of the activity of ants were carried out in July–August of 2013–2015 in broadleaf forests (Kyiv, Ukraine. Transects were located within foraging areas of three dominant species Formica rufa L., Lasius fuliginosus (Latreille), and L. emarginatus (Olivier). Thirteen species of ants were encountered on the soil surface. Factors that influence the activity of ants in forests may be ranked by importance as follows. (1) Climatic factors: (a) air temperature and soil humidity; (b) mean monthly rainfall; (c) air humidity. (2) Phytogenic factor (tree species composition). 3. Interspecific hierarchy of ants (primarily, territoriality of the dominant species).