Diurnal periodicity in the biting activity of horsefly species in the Kopacki rit Nature Park, Croatia (Diptera: Tabanidae)

Adult [female] of Tabanidae species were collected during the summer of 2004 in the Tikves forest within the Kopacki rit Nature Park (E Croatia). Analysis of the biting activity was made on Tabanid collected by four linen canopy traps. The daily trapping period was between 07.00-19.00 h by every two hours emptying the traps. Throughout 14 sampling days a total of 5.505 individuals was collected and classified to 20 species. The biting activity of horseflies was studied only for the five most abundant species; Atylotus loewianus (Villeneuve 1920), Tabanus bromius Linnaeus 1758, Tabanus maculicornis Zetterstedt 1842, Tabanus tergestinus Eager 1859 and Tabanus sudeticus Zeller 1842. The five most abundant species together represented 95.05% of the total catch. A single peak of the biting activity was established for all five of them: Atylotus loewianus, Tabanus bromius, Tabanus maculicornis and Tabanus sudeticus were most active during midday and early afternoon between 11.00-13.00 h at air temperatures from 24[degree]-28[degree]C. In Tabanus tergestinus, the maximal activity occurred earlier, from 9.00-11.00 h at air temperatures between 23[degree]-26[degree]C. Multiple regression analysis showed that the peak of the biting activity for the five most abundant Tabanidae-species is significantly influenced by meteorological factors.