Protective covers impact honey bee colony performance and access to outside resources

Abstract

Protective crop covers are used extensively to protect high-value crops from bird and hail damage, however, these structures may present challenges for honey bees (Apis mellifera L.), the main pollinators in these systems. Some studies have indicated that protective covers result in declines in colony size and resource storage, but few replicated field trials exist. To determine the impact of protective cropping structures on honey bee brood production and resource storage, 14 honey bee colonies were placed inside and outside of protective covers on four blueberry (Vaccinium corymbosum and V. virgatum) farms in northern New South Wales, Australia. We measured changes in brood production, pollen and honey storage, hive weight and ambient hive temperature fortnightly over a 12-week period. Brood production, pollen and honey storage, and hive weight all displayed greater reductions within four weeks of placement under net cover, compared to hives outside of net cover. Although brood and honey metrics gradually increased in all hives during the remainder of the 12-week monitoring period, hives located under protective netting had relatively smaller gains in brood production and pollen storage when compared to hives located outside the protective covering. Hives under protective netting that were in the shade and/or whose entrances were facing south were most impacted by the end of the monitoring period. Our findings highlight the need for protected crop management strategies to consider pollinator health as well as crop pollination needs so that both bee health and pollination services are maintained in these systems.