Apple orchards feed honey bees during, but even more so after, bloom

Many of the fruits that add diversity and nutrition to our diet are wholly or partially dependent upon flower-visiting insects. For example, apples (Malus spp.) are self-incompatible and therefore rely on insect pollinators for fruit development and seed production. Honey bees (Apis mellifera) are often migrated into these orchards when the apples are in bloom. While previous studies have focused on the impact of honey bees to fruit orchards, fewer studies have examined the reciprocal relationship of the orchards to honey bees, particularly if the bees are in the orchard for the entire foraging season, not just during bloom. Here we investigated the foraging dynamics of honey bees in apple orchards in Virginia for two full foraging seasons (April-October, 2018-2019). We decoded, mapped, and analyzed the waggle dances (n = 3710) made by returning foragers, which communicate the distance and direction from the hive to valuable resources, usually nectar or pollen. We found that bees foraged locally at <2 km throughout the season in both 2018 and 2019, with some long-range recruitment of up to 11 km. Contrary to our expectations, apple blooms did not drive honey bee foraging. We determined in our calculations of percent (%) foraging that honey bees recruit more to the apple orchards after the bloom than during the bloom (29.4% vs. 18.6% in 2018 and 28.5% vs. 21.4% in 2019, respectively). Interestingly, honey bees recruited more to forests while the apples bloomed (36.9% and 25.7% in 2018 and 2019, respectively). Lastly, our odds ratio analysis, which includes a distance correction, indicates the honey bees were more than twice as likely to recruit to apple orchards in June, which is after the bloom, than in April or May, which is during the bloom. Our ground truthing revealed that post-bloom apple orchards provided foraging opportunities on the growing understory of red and white clover (Trifolium spp.) and plantain (Plantago spp.). These data might therefore have important implications for best management practice decisions for bees located in fruit orchards.

Automated summary

Many fruits rely on flower-visiting insects for their development, and this study focused on the foraging dynamics of honey bees in apple orchards. The researchers found that honey bees mainly foraged locally throughout the season, with some long-range recruitment. Interestingly, the bees recruited more to forests during the apple bloom. Post-bloom apple orchards provided foraging opportunities on the growing understory of certain plants, such as clover and plantain.