NORTH-WESTERN JOURNAL OF ZOOLOGY 10 (2): 404-412 ©NwjZ, Oradea, Romania, 2014 Article No.: 141104 http://biozoojournals.ro/nwjz/index.html Lasius fuliginosus (Hymenoptera: Formicidae) shapes local ant assemblages Piotr ŚLIPIŃSKI1,*, Bálint MARKÓ2, Kamil RZESZOWSKI1, Hanna BABIK1 and Wojciech CZECHOWSKI1 1. Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00-679 Warsaw, Poland, E-mails: [email protected], [email protected], [email protected], [email protected]. 2. Hungarian Department of Biology and Ecology, Babeş-Bolyai University, Clinicilor str. 5-7, 400006 Cluj-Napoca, Romania, E-mail: [email protected]. * Corresponding author, P. Ślipiński, E-mail: [email protected] Received: 20. December 2013 / Accepted: 22. March 2014 / Available online: 17. October 2014 / Printed: December 2014 Abstract. Interspecific competition is a major structuring force in ant assemblages. The assemblages are organized hierarchically, with territorial species as top competitors. In boreal areas and in the temperate deciduous forest biome common territorials are species of the subgenus Formica s. str. They are well known for their negative impact on lower-ranked ant species. Less is known, though the structuring role of Lasius fuliginosus, another territorial ant species. Some earlier studies have shown or suggested that it may restrictively affect subordinate species (including direct predation toward them) even stronger than wood ants do. In the present study we compared species compositions and nest densities of subordinate ant species within and outside territories of L. fuliginosus. The results obtained confirmed that this species visibly impoverishes both qualitatively (reduced species richness, altered dominance structures) and quantitatively (decreased nest densities) ant assemblages within its territories. Furthermore, contrary to what is known in wood ants, there was not detected any noticeable protective effect of L. fuliginosus for Formica fusca living within the L. fuliginosus territory against raids of the slave-maker Formica sanguinea. Two colonies of L. fuliginosus living under different environmental conditions were studied – one in Finland, and one in Poland. Key words: community structure, competition hierarchy, Formica sanguinea, intraspecific relations, nest density, territoriality. Introduction on occurrence, abundance, foraging possibilities, and reproductive output of subordinates, colonies Interspecific competition has an important role in of territorials are acting as organizing centres of structuring ants’ communities (Reznikova 1983, ant assemblages (Savolainen & Vepsäläinen 1988, Savolainen & Vepsäläinen 1988, Hölldobler & Wil- 1989, Savolainen et al. 1989, Pisarski & Vepsäläin- son 1990, Punttila et al. 1996, Sanders & Gordon en 1989, Reznikova 1999, Czechowski et al. 2013). 2003, Adler et al. 2007, Cerdá et al. 2013, Generally speaking, subordinate ant species Czechowski et al. 2013). Palaearctic multi-species are doing worse living within than outside the ar- ant assemblages – especially well-examined in this eas of territorial species. In certain situations, respect both in northern temperate deciduous and however, nesting ‘under the wing‘ of the top com- boreal forest zones (e.g. Pisarski 1980, Vepsäläinen petitor appears to be advantageous for some sub- & Pisarski 1982, Pisarski & Vepsäläinen 1989), and ordinate species. Thus, members of the subgenus southern temperate steppe areas (Reznikova 1980, Serviformica (e.g. Formica fusca) are protected by 1983) – are known to have three-level hierarchical territorials against slave-making raids of the facul- structure, with territorial species constituting the tative slave-maker Formica sanguinea (Czechowski highest tier of the competition hierarchy (Vep- 1999, 2000a, Czechowski & Vepsäläinen 2001). It säläinen & Pisarski 1982, Savolainen & Vepsälä- may even happen that Serviformica populations inen 1988, Pisarski & Vepsäläinen 1989). Colonies within such territories of wood ants are signifi- of territorial species defend not only their nests cantly more abundant or successful, than outside and food sources, but they also defend their whole them (Punttila et al. 1996, Czechowski & Vep- foraging areas against other territorial colonies säläinen 2001, Czechowski & Markó 2006, (both con- and allospecific). Below them, there are Väänänen et al. 2010). two tiers of subordinated ants: (1) encounter spe- The vast majority of the data on the role of ter- cies, which defend their nests and food sources, ritorial ant species in structuring ant assemblages and (2) submissive species, which defend only in temperate Europe concerns species of the sub- their nests. Due to restrictive impact of territorials genus Formica s. str. (e.g. F. rufa, F. polyctena, F. Lasius fuliginosus shapes ant assemblages 405 aquilonia in forests, and F. pratensis in grasslands) thermophilic oligotope of deciduous forest, encountered also as top dominants – both in the context of their in- in mixed and coniferous forests. It is a dendrobiont nesting fluence on subordinate species (e.g. Stebaev & in cavities under the trunk and roots of usually living trees, both deciduous and coniferous; sometimes – after death and Reznikova 1972, de Bruyn 1978, Mabelis 1984, decay of the tree – in the ground amongst root remnants. Savolainen 1991, Savolainen & Vepsäläinen 1988, The empty spaces in wood and soil are filled with carton 1989, Pisarski & Vepsäläinen 1989, Savolainen et nests of chewed wood particles, glued and impregnated al. 1989, Vepsäläinen & Savolainen 1990), and their with honeydew and reinforced by hyphae of myrmecophilic ’protective’ effect on potential slave species of fungi. Colonies are very populous with up to two million Formica sanguinea (Punttila et al. 1996, Czechowski workers, often polygynous and polycalic. Foragers form dis- & Vepsäläinen 2001, Czechowski & Markó 2006, tinct narrow trails marked out pheromonally, that lead to aphids on trees and bushes; often these trails partly run in Väänänen et al. 2010). Incomparably less is known underground tunnels. The ants feed on aphid and coccid though about a role of other territorial ant species, honeydew and small insects. In conflict situations they use like Lasius fuliginosus. Current data on its influence dendrolasin – a substance produced in their mandibular on the structure of ant assemblages are scarce and glands with very strong deterring effect on other ants mainly vague or episodic. There is no doubt, how- (Pavan 1959). Lasius fuliginosus is an obligate temporary so- ever, that L. fuliginosus is a strongly competitive cial parasite: young queens start new colonies in nests of territorial species, able to successfully compete for species of the subgenus Chthonolasius (Seifert 2007, Czechowski et al. 2012). area and food sources (e.g. trees with honeydew- providing aphids) with other territorial species in- Colonies studied, sites and field methods cluding wood ants (Zakharov 1972, Romanova Two fairly large colonies of L. fuliginosus living under dif- 1975, Mabelis 1984, Czechowski 2000b, ferent environmental conditions were studied – one in Czechowski et al. 2013) and Liometopum spp. Finland (colony F), and one in Poland (colony P). In (Kupyanskaya 1988, Petráková & Schlaghamerský Finland (site F), the studies were conducted in June 2009 near the village of Tvärminne on Hanko Peninsula 2011). Lasius fuliginosus is also known to be a facul- (59°50’N, 23°15’E). The colony nested within the vast tative myrmecophage: it happens to attack colo- sand dune complex overgrown with Scotts pine (Pinus nies of subordinate species and pillage larvae and sylvestris) forest. The same colony F was object of several pupae from their nests (Czechowski 2000b, 2002, case studies (Czechowski 1999, 2000a, Czechowski et al. Markó et al. 2013). It also interferes during raids of 2011). Colony F nested in and under an old pine stump F. sanguinea when they violate its territory within a small patch (ca 350 m2) of pine forest on a slope (Czechowski 1999, 2000a). However, apart from of the sand dune. There was also an auxiliary nest in a willow within this patch. The territory of the colony con- few case studies (e.g. Czechowski et al. 2013), sisted of the above-mentioned forest patch on the slope there is not any comprehensive study available on and a fragment of a pine forest belt stretching along the the general features of the effect of this species on foot of the dune. These two parts of the territory, divided local ant assemblages. with a sandy road, were connected by two L. fuliginosus The aim of this study was to examine to what trails crossing the road. The entire hourglass-shaped terri- extent L. fuliginosus is able to shape the ant assem- tory (Fig. 1) was about 1100 m2, and included more than blage within its territory considering in two as- 70 trees. The soil was covered with a thick layer of needle litter, cones and dry twigs; in places there were moss and pects: (1) the impact on the occurrence and abun- lichen, with patches of heather (Calluna vulgaris) here and dance of subordinate species in general, and more there. In the vicinity, in a gap in the forest belt, a six-nest specifically (2) the potential ‘protective’ effect on complex of Formica sanguinea occurred. Apart from these, the abundance of Serviformica species threatened at least one more F. sanguinea colony nested on the other by the facultative slave-maker Formica sanguinea side of the L. fuliginosus territory. Individual nests of F. through inhibition