Nesting boxes: Improve tree pollination with wild bees (BIOFRUITNET Practice Abstract)

Summary

Wild bees visit more flowers than honeybees; some can be active at lower temperatures (Picture 1). Thanks to these two advantages, they increase fruit yields.
Practical recommendation
• To make wild bee nesting logs, drill horizontal holes 2 to 10 mm in diameter and 9 cm deep in a piece of wood without bark of about 30 x 15 x 10 cm. Place the logs high up in the orchard or its immediate vicinity.
• To make a bundle of hollow sticks (Picture 2), cut hollow stems 20 cm long with an internal diameter of 2 to 10 cm (bamboo, reeds, elderberry). Assemble the stems into a bundle and place them in a tube made of waterproof material. Place the bundles in the plots with the stems horizontal.
• Many types of bee boxes are also available from specialist manufacturers (Picture 3).
Best combine these structures with the following measures:
• Sow flower strips in the orchard alleys and see that they start flowering when the apple blossom ends. This allows the wild bees active on apple blossoms to have pollen sources after apple blossoming has fin-ished (see Further reading).
• Mow weeds not simultaneously in all the alleys (e.g., only half or third of the alleys) to always keep some areas with flowers.
• During the flowering period of trees, weeds, or plant cover, avoid applying products that are toxic to bees and favour night spraying when bees are less active.
• Plant mixed hedgerows around orchards with early flowering species such as hazel, dogwood, alder, and wild cherries.