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the Pariżske moćiare NNR belonging to species of eudominant presence despite of the rare and endangered charakter the species in the Czech Republic and Poland. In the contrary this species was not caught in the Żitavsky luh NR. ĆepelAk (1986) and Straka & Majzlan (2010) stated the occurrence of L. vittata in the Sur NR in Slovakia. The presence of the species is also known in Biospheric Rreserve (BR) Palava in the Czech Republic (LASKA & MazAnek 1998). The species M. peregrinus was identified in Slovakia in locations Vinne jazero and Lakśanska Nova Ves (ĆepelAk 1986) and in the Żitavsky luh NR (KrAlikovA 2006). The occurrence of the species in the Palava BR is mentioned by LAska & MazAnek (1998). The other wetland species P. versicolor, Platycheirus angustatus (Zetterstedt), P. lulviventris, Platycheirus perpallidus VERRALL and Tropidia scita (Harris) belong among rare species in Slovakia according to CepelAk (1986). P. perpallidus has been categorized as a endangered species in the Czech Republic according to MazAnek & BartAk (2005). The stated species has been occurred in the Pariżske moćiare NNR and Zitavsky luh NR, too (KrAlikovA 2005, 2006).

Our identified species Lejogaster tarsata (Megerle in Meigen) belongs to vulnerable species according to categorisation of MazAnek & BartAk (2005) in the Czech Republic. In 2008 at the site 3 an interesting occurrence of Microdon devius (LlNNAEUS) classified by SPEIGHT (2010) as the nonę wetland species was noted. According to the classification of danger of hoverflies in the Czech Republic (MazAnek & BartAk 2005), the highest abundance of endangered species was found out at the site 2, in 2008 (4 species from which 2 classified as critically endangered and 2 as vulnerable species) and at the site 3, in 2007 (3 species from which 2 classified as critically endangered and 1 as vulnerable species). From the above mentioned occurrence of species the Aluvium Zitavy NR can be evaluated as high natural value area for syrphidae and the research of hoverflies contributes to better knowledge of biological value of this area.

The ecological value of study site was evaluated by Shannon index of diversity (H ) and eąuitability (e), see Table 2.

Study site	Number of species	H'		eąuatibility	Number of specimens
1/2007	17	1.82	2.83	0.64	134
2/2007	19	2.14	2.94	0.73	122
3/2007	21	2.43	3.04	0.80	167
1/2008	18	2.25	2.89	0.78	124
2/2008	25	2.76	3.22	0.86	103
3/2008	25	2.35	3.22	0.73	111
1/2009	19	2.18	2.94	0.74	81
2/2009	26	2.83	3.26	0.87	93
3/2009	24	2.35	3.18	0.74	112

Tab. 2. Yalues of the Shannon index (H' a H_max) and index eąuitability (e).

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