Comparing the performance of native and managed pollinators of Haskap (Lonicera caerulea: Caprifoliaceae), an emerging fruit crop

Abstract

Fruit set in many crops is dependent on pollinating insects, but the pollination performance of floral visitors can vary tremendously among taxa. Apis mellifera L. is the primary managed pollinator used for most crops, but alternative managed bee species or wild pollinators may be more effective and efficient pollinators. In this study, we compared the performance of A. mellifera to commercial Osmia lignaria Say and wild Bombus spp. as pollinators of Haskap (Lonicera caerulea L.), an early flowering fruit crop grown in northern regions of North America, Europe, and Asia. We conducted field experiments that compared single visit pollen deposition (SVD), foraging behaviour, and pollen load composition among the three taxa. We found that individual Bombus spp. had the highest SVD levels, visited the most flowers per time interval, had high floral constancy, and could tolerate the colder temperatures often experienced during Haskap flowering. Apis mellifera had the lowest SVD levels, spent three times as long per flower as Bombus spp., and were not active during cooler temperatures. However, their potential for high densities in good weather and their affinity for Haskap suggest that as a colony they are important for Haskap pollination. Osmia lignaria rarely visited Haskap when alternative forage such as willow (Salix) was available and therefore contributed very little to Haskap pollination. These results emphasize the economic importance of wild bees in agro-ecosystems, and we conclude that pollination in Haskap orchards can be optimized by providing year-round forage and nesting habitat for wild Bombus spp., in addition to pollination by A. mellifera.