Comparative Pollination Efficacies of Five Bee Species on Raspberry

Area of Science:

• Horticulture
• Entomology
• Pollination Biology

Background:

• Raspberry (Rubus idaeus) cultivars are largely self-fertile but require insect pollination for optimal fruit development.
• Incomplete self-pollination leads to small, crumbly fruits, necessitating external pollinators.
• Rising honey bee (Apis mellifera) rental costs drive the search for alternative managed pollinators for raspberry production.

Purpose of the Study:

• To compare the pollination efficacy of honey bees with other manageable bee species on red raspberries.
• To determine if alternative pollinators offer superior efficacy to justify their adoption over honey bees.

Main Methods:

• Quantified pollination efficacy by counting drupelets per flower after a single bee visit.
• Compared single-visit efficacy to unvisited and hand-pollinated controls.
• Calculated pollination effectiveness scores for each bee species.

Main Results:

• All five tested bee species (honey bees, Bombus spp., Osmia lignaria, O. aglaia, O. bruneri) demonstrated equal effectiveness in pollinating raspberries.
• Honey bees remain the most cost-effective option for open-field raspberry pollination on a per-forager basis.
• Mason bees and bumble bees showed potential utility in cooler weather or protected cultivation systems.

Conclusions:

• No single bee species significantly outperformed others in pollination efficacy for red raspberries under the study conditions.
• Honey bees are the most economical choice for large-scale, open-field raspberry pollination.
• Alternative pollinators like mason bees and bumble bees may offer advantages in specific niche environments unfavorable to honey bees.