Wild Bees Drive Fruit Quality Indirectly Via Seed Set in Highbush Blueberry: A Quantitative Synthesis

Abstract

Insect-mediated pollination enhances global production of many crops, and evidence highlights that insect pollination can also improve crop quality. The link between insect-mediated pollination and crop quality driven not only by insect pollinators, but by a complex of interactions between pollinators, plant genotype, cross pollination, plant physiology, environmental conditions, farm management, etc. To further optimize food production, the link between insect-mediated pollination and crop quality is requires additional examination. In this study, we used a dataset of 260 sites across multiple production regions to explore how flower visitation of honey bees and wild bees drives fruit quality in highbush blueberry, measured as fruit weight. Our hypothesis was that fruit set and seed set directly impact fruit quality, while bee visitation affects fruit quality indirectly through fruit set and seed set. Direct and indirect effects were evaluated using both linear and structural equation modeling (SEM). Our analyses show that seed set mainly influences fruit quality and SEM analyses reveal a positive cascading effect of wild bee visitation on fruit quality, mediated via seed set. Similar effects of fruit set or honey bee visitation on fruit quality were not detected. In sum, this study highlights that bee visitation mainly affects blueberry fruit quality indirectly and that analyses beyond the pollinator visitation-crop quality relation can inform pollination research and management. Possible measures to improve crop quality by enhancing pollinator visitation by means of farm management or landscape management are discussed.

Keywords: Crop pollination, Fruit weight, Pollinators, Vaccinium spp