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Research article - Peer-reviewed, 2020

Wildflower plantings promote blue orchard bee, Osmia lignaria (Hymenoptera: Megachilidae), reproduction in California almond orchards

Boyle, Natalie K.; Artz, Derek R.; Lundin, Ola; Ward, Kimiora; Picklum, Devon; Wardell, Gordon I.; Williams, Neal M.; Pitts-Singer, Theresa L.


Concerns over the availability of honeybees (Apis mellifera L.) to meet pollination demands have elicited interest in alternative pollinators to mitigate pressures on the commercial beekeeping industry. The blue orchard bee, Osmia lignaria (Say), is a commercially available native bee that can be employed as a copollinator with, or alternative pollinator to, honeybees in orchards. To date, their successful implementation in agriculture has been limited by poor recovery of bee progeny for use during the next spring. This lack of reproductive success may be tied to an inadequate diversity and abundance of alternative floral resources during the foraging period. Managed, supplementary wildflower plantings may promote O. lignaria reproduction in California almond orchards. Three wildflower plantings were installed and maintained along orchard edges to supplement bee forage. Plantings were seeded with native wildflower species that overlapped with and extended beyond almond bloom. We measured bee visitation to planted wildflowers, bee reproduction, and progeny outcomes across orchard blocks at variable distances from wildflower plantings during 2015 and 2016. Pollen provision composition was also determined to confirm O. lignaria wildflower pollen use. Osmia lignaria were frequently observed visiting wildflower plantings during, and after, almond bloom. Most O. lignaria nesting occurred at orchard edges. The greatest recovery of progeny occurred along the orchard edges having the closest proximity (80 m) to managed wildflower plantings versus edges farther away. After almond bloom, O. lignaria nesting closest to the wildflower plantings collected 72% of their pollen from Phacelia spp., which supplied 96% of the managed floral area. Phacelia spp. pollen collection declined with distance from the plantings, but still reached 17% 800 m into the orchard. This study highlights the importance of landscape context and proximity to supplementary floral resources in promoting the propagation of solitary bees as alternative managed pollinators in commercial agriculture.


floral resources; managed pollinators; pollen; Prunus dulcis

Published in

Ecology and Evolution
2020, volume: 10, number: 7, pages: 3189-3199
Publisher: WILEY

Authors' information

Boyle, Natalie K.
Penn State Univ
Artz, Derek R.
University of California Davis (UC Davis)
Swedish University of Agricultural Sciences, Department of Ecology
Ward, Kimiora
Univ Calif Davis
Picklum, Devon
Univ Nevada
Wardell, Gordon I.
No organisation
Williams, Neal M.
Univ Calif Davis
Pitts-Singer, Theresa L.

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