LIGHT-TRAP CATCH OF THE FLUVIAL TRICHOPTERA SPECIES IN CONNECTION WITH THE GEOMAGNETIC H-INDEX

The study deals with the change of light-trap catch of twelve caddisfly (Trichoptera) species of Danube and Tisza rivers in connection with the geomagnetic horizontal component (H-index). The numbers of specimens caught of all species were calculated relative catch values. These daily relative catch data were assigned to the daily values of geo­magnetic field above 21,250 nT (H-index). We correlated the daily catch results pertaining to the daily values of geometric H-index values.

The catch of nine species increased in parallel with increasing values of the H-index, but the catch of two species declined. There was one species which has decreasing catch at River Danube, but it was increasing at River Tisza.