Study of fruit set and fruit quality of 'Conference' pears and 'Jonagold' apples in orchards supplemented with bumblebee hives

Both apple (Malus × domestica Borkh.) and pear (Pyrus communis L.) belong to the Rosaceae family, and many cultivars are self-incompatible and need cross pollination for pollination and consequently seed and fruit set. However, the introduction of honey bees is quite common in apple orchards but it is less applied in pear orchards. The aim of this study was to investigate the effect of the introduction of bumblebee hives on the pollination success, fruit set and fruit quality of ‘Conference’ pears and ‘Jonagold’ apples. In 2015 and 2016, bumblebee hives were placed in the centre of a ‘Conference’ and a ‘Jonagold’ orchard. Fruit set was monitored on trees at several distances from the hives, and from the same trees pear fruits were harvested and analysed for fruit quality parameters (length, width, weight, firmness, soluble solids content, acid content and the number of seeds). In 2015, no effect of the distance to the hives on fruit set was found for ‘Conference’, but the soluble solids content increased and the acid content decreased significantly with distance from the hives. In 2016, again no effect of the distances from the bumblebee hives on fruit set was observed, but fruit quality parameters such as the number of seeds and the acid content increased significantly and soluble solids content decreased significantly at 25 m from the bumblebee hives compared to fruits at 0-15 and 50 m from the bumblebee hives. Furthermore, the experiments on ‘Jonagold’ in 2016 did not indicate any differences in fruit set and fruit quality for the different distances from the bumblebee hives. In conclusion, ‘Conference’ trees close to the hives had a higher acid content and a lower soluble solids content, with the other quality parameters being variable over the years and over the distances from the bumblebee hives. In the ‘Jonagold’ orchard no differences were found in fruit quality and quantity among distances from the bumblebee hives.