Proximity to flowering weeds on fallow fields improves honey bee colony growth in late winter/early spring

It is well-accepted that pollinators are nutritionally stressed on agricultural lands, but little is known about pollinator floral resource use, or ways to improve nutrition, in the late-winter/early-spring period (LWES). LWES is a critical time during which honey bee colonies re-build their populations after winter, and prepare to reproduce by swarming. Maximum growth requires adequate nutrition (particularly pollen), and growth during this time frame sets a hive’s reproductive potential for the remainder of the active season. We hypothesize that early-blooming winter annual plants (e.g., deadnettles and mustards), present in high abundance on and around fallow corn and soybean fields, provide important nutrition to bees during LWES. For three years (2019-2021) we assessed how near-hive access to blooming winter annual plants impacted honey bee hive weight gain, food collection, and brood production. In two of three years, hives on sites with abundant winter annuals nearby (within 200 m) showed increased growth during the ~6-week LWES period. In 2021, we sampled 19 independent sites and found evidence for diminishing returns when hives were on sites with extremely high winter annual abundance. Because winter annuals are most prevalent on fallow corn and soybean fields, these data could suggest a trade-off of proximity to these land types, e.g., pesticide exposure. Future studies will evaluate this possibility, as well as the extent to which winter annuals are represented in hive pollen samples. Encouraging winter annual growth on fallow lands could inexpensively improve bee nutrition, with implications for stakeholders including beekeepers, growers, and diversified farmers.