In recent years, the use of pesticides in apple orchards and other cultivated plants has given rise to several discussions concerning their influence on the health of the honeybees. As a matter of fact, it has been shown that the use of plant protection systems may affect the health of the entire colony, starting from the forager bees, to the nurse bees, larvae and up to the queen. However, it has not yet been demonstrated whether the chemical residues found in pollen loads derive from the crop or plants growing within the treated orchards or from the surrounding species, which have been contaminated by drift from the nearby periodic spraying process of the protection products. This thesis aims to discover the origin of the contaminations, by collecting pollen loads directly from forager bees present on single plant species, and then analyzing them for the presence of multi-residual chemicals. Bee- pollen samples of a net weight of minimum two grams will be collected during the blooming period of specific plants, addressing our attention specifically to the willow tree (Salix spp.) and cherry tree (Prunus avium), between March and April 2019. The choice of these species is due to the results of recent analysis, where for instance samples with high portions of pollen from Salix spp. showed relevant contaminations with plant protection products harmful to bees. The collected samples will be subsequently sent to a laboratory for multiresidual analysisThis thesis project is a result of a fruitful collaboration and past investigations between the Research Centre Laimburg and the Free University of Bozen-Bolzano.