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The facultative enslaver Formica sanguinea Latr. uses as slaves F. fusca L. and other species of the subgenus Serviformica For. Earlier observations have shown or suggested that strong territorial wood-ant species, by defending their own territories, interfere with raids by F. sanguinea such that colonies of potential slave species gain protection against raids. At the population level, such protection should be visible as higher nest densities of F. fusca within than outside wood-ant territories, when both areas are within raiding distance of F. sanguinea. Here we tested this hypothesis by mapping nest densities of F. fusca. As expected, nest densities of F. fusca were higher within than outside wood-ant territories. In contrast, nest densities of two aggressive species, Lasius platythorax Seifert and L. niger (L.), unsuitable as slaves, were as expected lower within than outside wood-ant territories. Our results concur with earlier studies based on pitfall trapping, baiting experiments, and in situ observations on raids. The results also show that the positive impact of indirect protection provided by wood ants against raids may outweigh the direct negative impact of wood ants on F. fusca nesting within their territories. We discuss the geographic and habitat cooccurrences of wood ants, enslavers and potential slave species, and coverage of efficient indirect protection of potential slaves against raids.
Dealate gynes of Formica pratensis Retz., after their nuptial flight, were observed heading for colonies of their potential temporary host species in a jsand dune habitat în southern Finland. Two F. pratensis gynes, one within a nest area of Formica cinerea Mayr, and one close to a nest of Formica lusatica Seifert, were noticed walking with a F. cinerea and F. lusatica worker respectively in their mandibles. So far such peculiar behaviour preceding dependent colony founding has only been known in gynes of the subgenus Chthonolasius Ruzs., obligate temporary social parasites. Observations were carried on in June 2006.
By protecting their territory against all territorial ants, Formica rufa L. indirectly protected F. fusca L., nesting within their territory, against F. sanguinea Latr. raids. The permanent costs to F. fusca caused by highly aggressive F. rufa within their territories were outweighed by the benefits obtained by F. rufa’s protection against periodic raids of F. sanguinea. We interprete our findings in the light of the hierarchy competitive framework as follows.
The paper discusses the directionality of slave raids of a colony of Polyergus rufescens (Latr.), an obligate European slavemaking ant species, in the presence of colonies of Formica sanguinea Latr., a facultative slavemaker, in the neighbourhood. Both these social parasites use the same host species. The results strongly suggest that P. rufescens avoided raiding the area occupied by its competitor. An explanation is offered based on a demonstrated at the same time tendency of this species to avoid dangerous places.
The paper is devoted to enslavement of adult Formica cinerea cinerea Mayr workers by Formica sanguinea Latr., a phenomenon hitherto unknown under natural conditions. Suc enslavement follows periodic invasions and temporary occupation of nests of slave species by F. sanguinea. During the occupation of their nest, some F. cinerea workers join the occupants colony. The studies were made m Poland and in Finland between 1994 and 1996.
A case of a queenright colony of Formica pratensis Retz. mixed with the workers of F. cinerea Mayr and some workers of F. sanguinea Latr. is described. The colony characterized by this composition has evolved from a pure F. cinerea colony that had been raided by F. sanguinea two years earlier. Another conflict with the same F. sangui nea revealed the composition of this colony. The presumed circumstances of the origin of the specific mixed colony are discussed in this paper.
The wood ant Formica polyctena Först, is a territorial species, a regular top dominant of ant communities in forests. Its colonies defend their whole foraging areas (territories) against other territorial ants, including F. sanguinea Latr., a common facultative slave-maker. The most frequent ‘victim’ ol F. sanguinea is F. fusca L., a ubiquitous submissive ant species. On the basis of some earlier observations, the presumption was made that F. polyctena, when defending its own territories, would indirectly protect F. fusca colonies, which nest within these territories, from F. sanguinea raids. It was expected that F. fusca should be more abundant in F. polyctena territories, than in F. sanguinea territories, while other subordinate ants, which are not potential slaves of F. sanguinea, should not show such difference. This hypothesis was supported by the results of the baiting experiments carried out in the Białowieża Forest, NE Poland. The findings are discussed in the context of interspecific competition hierarchy in ants.
Formica sanguined Latr. occasionally takes wood ants as its slaves. Eleven nests of the former were experimentally provided with various amounts (10,000-250,000) of pupae of F. polyctena Foerst. or F. rufa L., and thus, mixed colonies with different proportions of slaves (29-96%) were obtained. The slaves destroyed the F. sanguinea colonies by eliminating their brood andqueen(s) (with no aggressiveness towards adult workers). The following year, even though F. sanguinea workers were still present, the slaves adopted young queens of their own species. Before their complete emancipation, the slaves fought on the side of the slavers during conflicts with conspecific ants, even against their former nestmates. Emancipation restored mutual comity between the ex-slaves and the unenslaved F. polyctena. At the same time, the ex-slavers lost their aggressiveness towards alien F. polyctena (but not vice versa). The mixed colonies were raided by foreign F. sanguinea. The studies were carried out in the Gorce Mts (the Western Carpathians) from 1987 to 1991.
The paper presents four cases of territorial ant colonies interfering in the course of Formica sanguinea Latr. raids against slave species which nest next to or in their territories. In three cases, Formica rufa L., when protecting its own territory, forced out (one case) or held (two cases) a raiding column of F. sanguinea, thus “saving” local Formica fusca L. nests from danger. In one case, Lasius fuliginosus (Latr.) did not let a F. sanguinea column pass its territory; to reach its target (a colony of Formica cinerea Mayr), the column had to by-pass the foreign territory.
Instances of presumed plesiobiosis (compound nests) of Lasius umbratus (Nyl.) with Formica sanguinea Latr. and of L. umbratus with Polyergus rufescens (Latr.) are presented. At the time of nuptial flights, on the surface of nests of the dulotic species (both with enslaved Formica cinerea Mayr workers) appeared young queens of a given slave-keeper and queens of L. umbratus; local workers of F. sanguinea and (or) of F. cinerea treated them in the same way. The phenomenon was observed from 1992 to 1995 near Puławy (S-E Poland).
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