2025/09/01 by Glen Trostle, Glen E. Trostle, Evan A Sugden +4
Agricultural and Biological Sciences · #Plant and animal studies #Insect and Pesticide Research #Plant Parasitism and Resistance
paper · doi:10.1093/ee/nvaf093
Osmia lignaria Say, the blue orchard bee is a native managed bee used to pollinate almond orchards and other early-blooming fruit crops. While this pollinator has proven effective for almond pollination, in-orchard propagation of this species has proven difficult. This study analyzed the usefulness of planting early blooming annuals within orchards to enhance on-site propagation of O. lignaria during pollination. Three native species were established between rows (inter-row flower strips, IRFS) in an isolated almond orchard in California's southern Central Valley. Pollination by O. lignaria was provided as a supplement to that provided by recommended levels of honey bee (Apis mellifera) hives. Proportion of supplemental pollen within brood provisions collected during the almond bloom period was analyzed with respect to the distance of nesting domiciles from IRFS and time interval. Maximal use of supplemental pollen occurred within a proximity of 0 to 40 m between th nest box and the IRFS. Activity levels of O. lignaria in the IRFS increased through the almond bloom period, peaking during the last third of the IRFS bloom. At the end of almond bloom, O. lignaria numbers sharply declined as honey bee numbers increased on the IRFS. Other native bee species also utilized the IRFS. This study reveals that 40 m or less between in-orchard floral plantings and nest boxes for O. lignaria optimized IRFS utilization, providing a pathway for determining nest box placement relative to IRFS plantings. Comments are made on practical considerations with respect to orchard management.