A new, practicable and economical cage design for experimental studies on small honey bee colonies

Bees are in decline globally as a result of multiple stressors including pests, pathogens and contaminants. The management of bees in enclosures can identify causes of decline under standardized conditions but the logistics of conducting effect studies in typical systems used across several colonies is complex and costly. This study details a practicable, new and economical cage system that effectively houses live honey bee colonies to investigate the impact of physical conditions, biological factors and environmental contaminants on honey bee health. The method has broad application for a range of effect studies concerning honey bee development, physiology, survival and population dynamics because it enables entire colonies, as opposed to individual workers, to be managed well in captivity

Does sorting by color using visible and high‐energy violet light improve classification of taxa in honey bee pollen pellets?

Premise: Pollen collected by honey bees from different plant species often differs in color, and this has been used as a basis for plant identification. The objective of this study was to develop a new, low-cost protocol to sort pollen pellets by color using high-energy violet light and visible light to determine whether pollen pellet color is associated with variations in plant species identity.
 Methods and Results: We identified 35 distinct colors and found that 52% of pollen subsamples (n = 200) were dominated by a single taxon. Among these near-pure pellets, only one color consistently represented a single pollen taxon (Asteraceae: Cichorioideae). Across the spectrum of colors spanning yellows, oranges, and browns, similarly colored pollen pellets contained pollen from multiple plant families ranging from two to 13 families per color.
 Conclusions: Sorting pollen pellets illuminated under high-energy violet light lit from four directions within a custom-made light box aided in distinguishing pellet composition, especially in pellets within the same color

The effect of protective covers on pollinator health and pollination service delivery

Protective covers (i.e., glasshouses, netting enclosures, and polytunnels) are increasingly used in crop production to enhance crop quality, yield, and production efficiency. However, many protected crops require insect pollinators to achieve optimal pollination and there is no consensus about how best to manage pollinators and crop pollination in these environments. We conducted a systematic literature review to synthesise knowledge about the effect of protective covers on pollinator health and pollination services and identified 290 relevant studies. Bees were the dominant taxon used in protected systems (90%), represented by eusocial bees (e.g., bumble bees (Bombus spp.), honey bees (Apis spp.), stingless bees (Apidae: Meliponini)) and solitary bees (e.g., Amegilla spp., Megachile spp., and Osmia spp.). Flies represented 9% of taxa and included Calliphoridae, Muscidae, and Syrphidae. The remaining 1% of taxa was represented by Lepidoptera and Coleoptera. Of the studies that assessed pollination services, 96% indicate that pollinators were active on the crop and/or their visits resulted in improved fruit production compared with flowers not visited by insects (i.e., insect visits prevented, or flowers were self- or mechanically pollinated). Only 20% of studies evaluated pollinator health. Some taxa, such as mason or leafcutter bees, and bumble bees can function well in covered environments, but the effect of covers on pollinator health was negative in over 50% of the studies in which health was assessed. Negative effects included decreased reproduction, adult mortality, reduced forager activity, and increased disease prevalence. These effects may have occurred as a result of changes in temperature/humidity, light quality/quantity, pesticide exposure, and/or reduced access to food resources. Strategies reported to successfully enhance pollinator health and efficiency in covered systems include: careful selection of bee hive location to reduce heat stress and improve dispersal through the crop; increased floral diversity; deploying appropriate numbers of pollinators; and manipulation of flower physiology to increase attractiveness to pollinating insects. To improve and safeguard crop yields in pollinator dependent protected cropping systems, practitioners need to ensure that delivery of crop pollination services is compatible with suitable conditions for pollinator health

Can Bees Detect Perfluorooctane Sulfonate (PFOS)?

The European honey bee (Apis mellifera) is an important crop pollinator threatened by multiple stressors, including exposure to contaminants. Perfluorooctane sulfonate (PFOS) is a persistent global contaminant that accumulates and bio-magnifies in food chains and is detected in honey. Even sublethal exposure to PFOS is detrimental to bee health, but exposure routes are unclear and nothing is known about bee response (detection, avoidance, or attraction) to PFOS. Using Y‐mazes, we studied the response of individual bees to PFOS‐spiked sugar syrup at four concentrations, 0.02, 30, 61 and103 µg L−1. Bee activity, choice behavior, and drink duration for unspiked and spiked sugar syrup was recorded for 10 min in the Y‐maze system. Most bees (≥80%) tasted and then drank the sugar syrup solutions, including the PFOS‐contaminated syrup. Only at 61 and 103 µg L−1 did bees significantly avoid drinking PFOS‐spiked syrup, and only when given a choice with unspiked syrup. When the choice of consuming unspiked syrup was removed, the bees drank PFOS‐spiked syrup at all the PFOS concentrations tested, and avoidance was not evident. Avoidance was not observed in any treatment at 0.02 or 30 µg L−1 PFOS, concentrations that are frequently reported in environmental waters in contaminated areas. These findings confirm that bees will access PFOS-contaminated resources at concentrations detrimental to the colony health, and provide evidence of potential exposure pathways that may threaten crop pollination services and also human health via food chain transfer in PFOS‐contaminated areas

Cavity occupancy by wild honey bees: need for evidence of ecological impacts

The European honey bee (Apis mellifera) is managed worldwide for honey production and crop pollination, and is an invasive species in many countries. Wild colonies occupy natural and human‐made cavities and are thought to impact other cavity‐using species. We reviewed documented evidence of wild A mellifera nesting sites globally via a literature review (27 relevant studies) and citizen‐science observations of wild honey bee colonies on iNaturalist (326 observations). Honey bee occupancy rates from published studies were typically low and occupation was often temporary. Citizen‐science data showed that most colonies in cavities had small or narrow entrance holes. Current evidence of perceived competition with honey bees in cavities is largely anecdotal and little is known about the long‐term impacts on survival and reproductive success of other cavity‐occupying species. To guide conservation policy and practice, more empirical research is needed to understand the ecological outcomes of competitive interactions in nesting cavities

Self‐compatible blueberry cultivars require fewer floral visits to maximize fruit production than a partially self‐incompatible cultivar

Effective pollination is a complex phenomenon determined by the outcome of the interaction between pollen transfer and a plants' pollinator dependency, yet most studies investigate pollinator effectiveness without consideration of plant mating system differences. We investigated pollinator effectiveness in three types of blueberry that differed in their degree of pollinator dependency as measured by plant mating system: two self-compatible highbush cultivars and one partially self-incompatible rabbiteye cultivar. We quantified pollinator effectiveness as a function of the fruit set and fruit weight resulting from single and multiple floral visits (2–15 visits), in comparison with estimates of fruit set and fruit weight resulting from experimental pollination treatments (open-pollination, cross-pollination and self-pollination). Single-visit effectiveness of fruit set was similar across pollinator taxa but considerably higher in both self-compatible cultivars. The probability of fruit set in all three blueberry types improved in response to an increasing number of visits, but this relationship was steeper in self-compatible cultivars: >90% probability of fruit set was achieved in three to five visits. In the self-incompatible rabbiteye cultivar, 58% fruit set was achieved with 15 visits. Multiple visits improved fruit weight by 27%–48% in self-compatible cultivars, but there was no relationship in rabbiteye. Pollination deficits in fruit set and fruit weight due to self-pollination were most pronounced in rabbiteye. Synthesis and applications. Improved understanding of cultivar-level mating system differences in plants will inform pollination planning and management in agroecosystems. Self-compatible (highbush) cultivars require less floral visitation to maximize fruit production. Therefore, these cultivars may be best suited to landscapes in which pollinator abundance is low, such as intensive and/or simple landscapes. In contrast, self-incompatible (rabbiteye) cultivars may benefit from the implementation of mixed-cultivar crop row plantings to facilitate cross-pollination