O. Merkl szerk.: Folia Entomologica Hungarica 66. (Budapest, 2005)

Table 2. Values used in calculation of saturation. S = Siófok Basin, SZE = Szemes Basin, SZI = Szigliget Basin, K = Keszthely Basin, a = saturation level of the curve, b = curve fitting parameter, r = correlation coefficient, t = calculated as (n / a) * 100, where n = total number of captured species in a basin a b r t S 21.4 0.30 0.94 93.5 SZE 23.6 0.21 0.95 93.2 SZI 18.7 0.23 0.95 90.9 K 30.3 0.21 0.96 89.1 In the case of semiaquatic Heteroptera the four most frequent species are those common in many other explorations in Hungary. The high frequency of small bugs is due to the development of various specific water nets using 0.2 mm density fabrics. Species frequency data Figures 1-2 illustrate the frequency of species in all samples collected between 1984 and 2002 by the authors. It is noticeable that Sigara striata is the most frequent aquatic Heteroptera species in the Lake. It was found at more than 80% of the sampling sites. Of the aquatic Heteroptera 22% of the species have a frequency 30 -i ye ar Fig. 3. Species accumulation curves of the aquatic and semiaquatic Heteroptera. Samples were taken between 1998 and 2002. s = spring, a = autumn. S = Siófok Basin, SZE = Szemes Basin, SZI = Szigliget Basin, K = Keszthely Basin, 98 = year 1998, 99 = year 1999, 00 = year 2000, 01 = year 2001, 02 = year 2002