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

ÁBRAHÁM L.: PIT BUILDING ANT-LION LARVAE 169 Methods and material In order to study the particles of substrate in different types of habitat the fieldworks were carried out in open and protected habitats of the South Transdanubian region in Hungary. The sampling site in open habitats on sandy bedrock were Kerek hill at Bélavár (BO), Csárda at Tótújfalu (TO), Nagyhomok at Nagybajom (NO) Kolláti grazing field at Látrány (LO). Samplings of protected habitats on sandy bedrock were carried out Tótújfalu: Csárda (TP), Bélavár: Kerek hill (BP), on clay bedrock: Zselickisfalud (ZP), Kaposvár: Gyertyános (KP), Ropoly (RP) and on loess bedrock Nagyharsány: Szársomlyó (NP). In order to study the particle size preferences of substrate (Figure 1) samples were taken with a plastic spoon only from the surface layer (as deep as 2-3 mm) of the pit's side (ps), from the edge of the pit (pe) and from 3 cm from the edge (pe3). Beside these a reference point (rp) was also located at every sampling location 10 cm from the edge of the pit which represented the general substrate distribution of the microhabitat. Figure 1: Sampling points in and around the pit Abbreviations: rp-reference point, pe3-3 cm from the edge, ре-edge of the pit, ps-side of the pit The samplings were carried out in all three larvae stages (LI, L2, L3) in a 10 xlO series by pits. Afterwards the small amount of particle samples added together type by type (sampling site, habitat, quality of substrate larvae stages) in order to obtain enough quantity of samples for the measurements. The dried substrate samples were sifted through sieves of different sizes (0.1, 0.2, 0.315, 0.4, 0.5, 0.8, 1, 2 mm). The fractions obtained by this method were weighed and the particle size distribution was calculated in percentage so that the substrate types of different specific weight could be compared. To analyze statistically the distances between the samplings cluster analysis (complete linkage, Eucledian distances) were chosen. Earlier studies (YOUTHED and MORAN 1969, KITCHTNG 1984, ALLEN and CROFT 1985, SIPOS 1986, LUCAS 1989b DEVETAK et al. 2005) in laboratory circumstances defined the particle size preferences of the pit-building ant-lion larvae. In order to define the larvae's preferences in natural environment the particle distribution of the pits (ps) and the reference point (rp) was compared. For the calculation of the preferences the Ivlev's electivity index (KREBS 1989} was used: Ei = (ri-ni)/(ri+ni) . ,