Herbs as a source of nutrition for flower-visiting hoverflies (Diptera, Syrphidae)

During two seasons of observations, 244 specimens of hoverflies belonging to 16 species and four trophic groups were collected from herb flowers. Predatory species constituted about 50% of all the registered species and from 55% (2010) to 64% (2011) of all the specimens found. The most numerous flower-visiting species within this group were small, poor flyers, typical of communities with low plants - Sphaerophoria scripta (Linnaeus 1758) (19.6% in 2010 and 23.5% in 2011) and Eupeodes corollae (Fabricius 1794) (13.4% and 12.1%, respectively). Both species were classified to the eudominant group. Syrphus vitripennis (Meigen 1822) and Melanostoma mellinum (Linnaeus 1758) were classed as dominants. Non-predatory saprophagous species from the subfamily Eristalinae constituted about 25% of all collected species; the phytophagous group was scarce represented by Eumerus funeralis (Meigen 1822), E. strigatus (Fallen 1817) and Merodon rufus (Meigen 1838). Of the coprophagous species, only Syritta pipiens (Linnaeus 1758) was collected (6.8-8.0%). There were clear differences between flowers in terms of feeding visits by adult hoverflies. Matricaria chamomilla L. and Thymus vulgaris L. were the most attractive flowers, whereas Origanum vulgare L., Carum carvi L., Lavandula angustifolia L. and Hyssopus officinalis L. were of an intermediate visit status and Ocimum basilicum L. was relatively under-visited.