Synthesis of highbush blueberry pollination research reveals region‐specific differences in the contributions of honeybees and wild bees

Abstract

Highbush blueberry production has expanded worldwide in recent decades. To safeguard future yields, it is essential to understand if insect pollination is limiting current blueberry production and which insects contribute to pollination in different production regions. We present a systematic review including a set of meta‐analyses on insect‐mediated pollination in highbush blueberry. We summarize the geographic distribution of research, the abundance of different pollinator taxa and their relative pollination contributions. Using raw data from 21 studies, totalling 496 site replicates, we determine the degree of pollination service and pollen limitation (i.e. combining open pollination levels with experimental bagged and/or hand pollination treatments), as well as the contribution of honeybees and wild bees to pollination (i.e. observational, open pollination). Most studies originate from North America, focusing on only a few cultivars. Honeybees are the dominant pollinator, and wild bees are occasionally abundant. Wild bees are more efficient pollinators on a single‐visit basis compared to honeybees, which increases their relative pollination contribution compared to their relative abundance. Insect‐mediated pollination services increased blueberry fruit set, berry weight and seed set (R2 values: 64.8%, 75.9% and 75.2% respectively). We often detected pollen limitation, indicated by an increase in fruit set, berry weight and seed set (R2: 10.1%, 18.2% and 21.5%, respectively), with additional hand pollination. Increasing visitation of honeybees and wild bees contributed to blueberry pollination by increasing fruit set (R2: 5.4% and 3.5%), berry weight (R2: 6.5% and 2.8%) and seed set (R2: 6.4% and 3.8%) respectively. Bee contributions to fruit set and berry weight were variable across regions. Synthesis and application: A diverse community of insects, primarily bees, contributes to highbush blueberry pollination and yield. However, pollination deficits are common. The finding that both honeybees and wild bees enhance pollination highlights the possibility of adopting different management strategies that utilize honeybees, wild bees or both depending on the specific context and region. This further emphasizes the general importance of conserving pollinator health and diversity. Our synthesis highlights data gaps and areas for future research to better understand the pollination contribution of different pollinators to crops that are expanding globally.

Optimal Pollination Thresholds to Maximize Blueberry Production

“…The need for animal pollination to promote blueberry productivity is broadly recognized (Eeraerts et al, 2023). Still, there is also evidence that the relationship between production and honeybee flower visitation rate might be negative (Miñarro et al, 2023;Ramírez-Mejía et al, 2023a, 2023bMallinger et al, 2021).…”

“…Highbush blueberry, Vaccinium corymbosum L., is a mass flowering crop dependent on animal-mediated pollination (Eeraerts et al, 2023). In general, increasing pollen deposition through flower visitation promotes blueberry production and reduces ripening time (Danka et al, 1993;Dogterom et al, 2000;Drummond, 2019;Nagasaka et al, 2022).…”

“…In general, increasing pollen deposition through flower visitation promotes blueberry production and reduces ripening time (Danka et al, 1993;Dogterom et al, 2000;Drummond, 2019;Nagasaka et al, 2022). This pollen demand is mostly covered by stocking honeybee hives --Apis mellifera L.--in blueberry fields (Bushmann and Drummond, 2020;Cavigliasso et al, 2021;Rollin and Garibaldi, 2019), with this species providing ~80% of flower visits to blueberry crop along its cultivation range (Eeraerts et al, 2023). In the USA alone, the contribution of honeybee pollination has an annual economic value of around 400 million USD for blueberry industry (Reilly et al, 2020).…”