Managed Bee Species Research Articles

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

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.

Disease associations between honeybees and bumblebees as a threat to wild pollinators.

Emerging infectious diseases (EIDs) pose a risk to human welfare, both directly1 and indirectly, by affecting managed livestock and wildlife that provide valuable resources and ecosystem services, such as the pollination of crops2. Honey bees (Apis mellifera), the prevailing managed insect crop pollinator, suffer from a range of emerging and exotic high impact pathogens3,4 and population maintenance requires active management by beekeepers to control them. Wild pollinators such as bumble bees (Bombus spp.) are in global decline5,6, one cause of which may be pathogen spillover from managed pollinators like honey bees7,8 or commercial colonies of bumble bees9. In our study, a combination of infection experiments with landscape scale field data indicates that honey bee EIDs are indeed widespread infectious agents within the pollinator assemblage. The prevalence of deformed wing virus (DWV) and the exotic Nosema ceranae is linked between honey bees and bumble bees, with honey bees having higher DWV prevalence, and sympatric bumble bees and honey bees sharing DWV strains; Apis is therefore the likely source of at least one major EID in wild pollinators. Lessons learned from vertebrates10,11 highlight the need for increased pathogen control in managed bee species to maintain wild pollinators, as declines in native pollinators may be caused by interspecies pathogen transmission originating from managed pollinators.

Supporting crop pollinators with floral resources: network-based phenological matching.

The production of diverse and affordable agricultural crop species depends on pollination services provided by bees. Indeed, the proportion of pollinator-dependent crops is increasing globally. Agriculture relies heavily on the domesticated honeybee; the services provided by this single species are under threat and becoming increasingly costly. Importantly, the free pollination services provided by diverse wild bee communities have been shown to be sufficient for high agricultural yields in some systems. However, stable, functional wild bee communities require floral resources, such as pollen and nectar, throughout their active season, not just when crop species are in flower. To target floral provisioning efforts to conserve and support native and managed bee species, we apply network theoretical methods incorporating plant and pollinator phenologies. Using a two-year dataset comprising interactions between bees (superfamily Apoidea, Anthophila) and 25 native perennial plant species in floral provisioning habitat, we identify plant and bee species that provide a key and central role to the stability of the structure of this community. We also examine three specific case studies: how provisioning habitat can provide temporally continuous support for honeybees (Apis mellifera) and bumblebees (Bombus impatiens), and how resource supplementation strategies might be designed for a single genus of important orchard pollinators (Osmia). This framework could be used to provide native bee communities with additional, well-targeted floral resources to ensure that they not only survive, but also thrive.

Weather-Dependent Pollinator Activity in an Apple Orchard, with Special Reference toOsmia cornutaandApis mellifera(Hymenoptera: Megachilidae and Apidae)

The foraging activity of pollinator insects in relation to weather factors (ambient temperature, solar radiation, relative humidity, and wind speed) was studied in an apple orchard with special reference to two managed bee species, Osmia cornuta (Latreille) and Apis mellifera L. Over the range of observed weather values, A. mellifera activity was significantly dependent on temperature, solar radiation, and wind speed; O. cornuta activity was dependent on solar radiation and wind speed. These results were confirmed through video recordings at one O. cornuta nesting shelter and one A. mellifera hive. For both species, daily activity started at lower temperatures than it ceased, whereas solar radiation did not differ between these two events. In general, O. cornuta was active from 10 to 12°C and 200 w/m2, and A. mellifera from 12 to 14°C and 300 w/m2. O. cornuta was the only bee species seen visiting apple flowers under strong wind or light rain. Because of its greater tolerance to inclement weather, O. cornuta pollinated apple flowers for longer periods (both daily and seasonally) than other flower visitors.