Andrena flavipes Panzer: dinamica di popolazione e preferenze florali in un’area dell’Italia nord-orientale

Andrena flavipes Panzer: population dynamics and floral preferences in a north-eastern Italian area. We studied the population dynamics and floral preferences of Andrena flavipes Panzer (Hymenoptera, Apoidea, Andrenidae), a common wild pollinator bee in the Friuli Venezia Giulia region (north-eastern Italy). In the periods 1997-2000 and 2006-2012, from March to September periodical field observations were carried out on the occurrence and foraging activity of A. flavipes at four sites located near the city of Udine. During the observation periods, the occurrence of females and males of A. flavipes was constant between March and August with two peaks in May and July; these data are in agreement with the literature, where the species is indicated as bivoltine. In both generations, the proportions of males and females resulted variable in the different months. Adults of A. flavipes mainly visited flowering plants belonging to the Asteraceae family on which 49.3% and 67.9% of females and males were detected, respectively; moreover, adults were observed on plants of ten other families, such as Lamiaceae, Fabaceae and Apiaceae. In particular, the plants most visited by females were Galinsoga parviflora, Leucanthemum vulgare, Thymus vulgaris, Trifolium repens and Coriandrum sativum, while males were frequently observed on Taraxacum officinale, Crepis vesicaria and T. vulgaris. This species, therefore, is broadly polylectic. Since A. flavipes is an important and useful pollinator of both cultivated and wild plants, its occurrence in agroecosystems must be preserved with planned actions, such as the maintenance and restoration of meadows, hedgerows and uncultivated areas, where the species can find suitable nest sites and plentiful food sources, as well as the correct management of crop rotations.