Ábrahám Levente: Válogatott tanulmányok II. - Natura Somogyiensis 9. (Kaposvár, 2006)

Ábrahám Levente: Pit building ant-lion larvae effect to the distribution of the substrate particles in their microhabitats - Tölcsérépítő hangyaleső lárvák hatása a szubsztrát szemcsék eloszlására élőhelyeiken

182 NATURA SOMOGYIENSIS Figure 19: The distribution of the substrate particles in and around the pit Figure 19 gives a graphic illustration of spatial general distribution given by proportion of the different sizes of particles. It is clear that the particles found 3 cm away from the edge of the pit (реЗ) is the coarsest in comparison with the reference point (rp). The substrate particle is the finest inside the pit (ps). The sizes of the particles taken from the edge of the pits (pe) are bigger than the ones taken from the pit side but smaller than реЗ. Their homogeneity is smaller than the samples from the pit side (ps) or the samples taken 3 cm from the edge (реЗ). Discussion In arboreal areas - except the Mediterranean regions - the pit-building ant-lion larvae have two characteristic habitats: open (unsheltered), protected (sheltered). Open habitats can only form on contiguous sandy stretches (WHEELER 1930, GEPP and HÖLZEI 1989). In this respect the distribution of sandy area in the Carpathian Basin (PÉCSI 1989) is in correspondence with the distribution of the pit-building ant-lion larvae living in open habitats (STEINMANN 1969, ASPÖCK et al. 1980, ÁBRAHÁM 1998). The preference of the ant-lion larvae living in protected habitat does not depend on the bedrock (BÍRÓ 1885a, 1885b). During the present investigation both types of habitats and the species characteristic of these habitats were found (ÁBRAHÁM 1998) therefore the quality of the substrate cannot be considered species dependent factor. On clay and loess bedrock open habitats cannot be formed in Central-Europe due to climatic reasons. The species typical of open and protected habitats are clearly distinguished. During the present research the particle size preferences of the pit-building ant-lion larvae occurring in open and protected habitat on sand, loess and clay substrate was studied. The common feature of the experiments of earlier studies (YOUTHED és MORAN 1969, KITCHING 1984, ALLEN és CROFT 1985, LUCAS 1982, 1986, 1989a, SIPOS 1986) is that these were manipulated under laboratory circumstances. As a result of these experiments it can be stated that there is an overlap in the preferences of the particle size of the ant-lion larvae, but this depended on the particle sizes used in a certain experiment.