Managed Honey Bee Apis Mellifera Research Articles

Fruit production in coffee (Coffea arabica L.) crops is enhanced by the behaviour of wild bees (Hymenoptera: Apidae)

AbstractChanges in floral visitors' diversity and community composition have been reported to affect coffee production, which optimal growing conditions are cool to warm tropical climates found in the coffee belt. However, few studies have focused on understanding how insects' foraging behaviour (e.g., contact with floral reproductive organs) relates with coffee production. Thus, it is important to consider floral visitors' foraging behaviour, as this can influence the transfer of conspecific pollen required for plant fertilisation, the efficiency of floral visitors and improve the pollination service provided. Here, we assessed how foraging behaviour of honeybees and stingless bees affects coffee fruit set and fruit weight in conventional and agroecological managed crops. We quantified local floral resources and recorded diversity, abundance and behaviour of floral visitors at eight pairs of sites with agroecological and conventional management systems to assess how foraging behaviour of honeybees and stingless bees affects coffee fruit set and fruit weight in both types of managed crops. We found that the managed honeybee Apis mellifera and three wild bees Tetragonisca angustula, Scaptotrigona mexicana and Partamona bilineata are the principal floral visitors of coffee crops in Guatemala, whose total abundance but not richness was higher in agroecological areas. Regarding their behaviours, we observed that the average number of flowers visited by P. bilineata and its behaviour of touching the nectaries of coffee flowers were positively related to fruit set, while only the percentage of A. mellifera carrying pollen was positively related with fruit weight, suggesting that although A. mellifera is found in large quantities, wild bees are also efficient pollinators of coffee in the region. Our findings also suggest that in other tropical regions where coffee is grown and honeybees have been observed as a primary pollinator, wild bees may play an important role when considering their behaviour. In the same way, coffee farms in Guatemala are a representation of the diversity of agroecosystems found worldwide, and thus, the study of foraging behaviour of managed and wild bees and the conservation of wild bee species in different coffee agroecosystems should be emphasised to improve the production of coffee and other cash crops.

Evidence of exploitative competition between honey bees and native bees in two California landscapes.

Human-mediated species introductions provide real-time experiments in how communities respond to interspecific competition. For example, managed honey bees Apis mellifera (L.) have been widely introduced outside their native range and may compete with native bees for pollen and nectar. Indeed, multiple studies suggest that honey bees and native bees overlap in their use of floral resources. However, for resource overlap to negatively impact resource collection by native bees, resource availability must also decline, and few studies investigate impacts of honey bee competition on native bee floral visits and floral resource availability simultaneously. In this study, we investigate impacts of increasing honey bee abundance on native bee visitation patterns, pollen diets, and nectar and pollen resource availability in two Californian landscapes: wildflower plantings in the Central Valley and montane meadows in the Sierra. We collected data on bee visits to flowers, pollen and nectar availability, and pollen carried on bee bodies across multiple sites in the Sierra and Central Valley. We then constructed plant-pollinator visitation networks to assess how increasing honey bee abundance impacted perceived apparent competition (PAC), a measure of niche overlap, and pollinator specialization (d'). We also compared PAC values against null expectations to address whether observed changes in niche overlap were greater or less than what we would expect given the relative abundances of interacting partners. We find clear evidence of exploitative competition in both ecosystems based on the following results: (1) honey bee competition increased niche overlap between honey bees and native bees, (2) increased honey bee abundance led to decreased pollen and nectar availability in flowers, and (3) native bee communities responded to competition by shifting their floral visits, with some becoming more specialized and others becoming more generalized depending on the ecosystem and bee taxon considered. Although native bees can adapt to honey bee competition by shifting their floral visits, the coexistence of honey bees and native bees is tenuous and will depend on floral resource availability. Preserving and augmenting floral resources is therefore essential in mitigating negative impacts of honey bee competition. In two California ecosystems, honey bee competition decreases pollen and nectar resource availability in flowers and alters native bee diets with potential implications for bee conservation and wildlands management.

Adaptation to vector‐based transmission in a honeybee virus

Global pollinator declines as a result of emerging infectious diseases are of major concern. Managed honeybees Apis mellifera are susceptible to numerous parasites and pathogens, many of which appear to be transmissible to sympatric non-Apis taxa. The ectoparasitic mite Varroa destructor is considered to be the most significant threat to honeybees due to its role in vectoring RNA viruses, particularly Deformed wing virus (DWV). Vector transmission of DWV has resulted in the accumulation of high viral loads in honeybees and is often associated with colony death. DWV has two main genotypes, A and B. DWV-A was more prevalent during the initial phase of V. destructor establishment. In recent years, the global prevalence of DWV-B has increased, suggesting that DWV-B is better adapted to vector transmission than DWV-A. We aimed to determine the role vector transmission plays in DWV genotype prevalence at a colony level. We experimentally increased or decreased the number of V. destructor mites in honeybee colonies, and tracked DWV-A and DWV-B loads over a period of 10months. Our results show that the two DWV genotypes differ in their response to mite numbers. DWV-A accumulation in honeybees was positively correlated with mite numbers yet DWV-A was largely undetected in the absence of the mite. In contrast, colonies had high loads of DWV-B even when mite numbers were low. DWV-B loads persisted in miticide-treated colonies, indicating that this genotype has a competitive advantage over DWV-A irrespective of mite numbers. Our findings suggest that the global increase in DWV-B prevalence is not driven by selective pressure by the vector. Rather, DWV-B is able to persist in colonies at higher viral loads relative to DWV-A in the presence and absence of V. destructor. The interplay between V. destructor and DWV genotypes within honeybee colonies may have broad consequences upon viral diversity in sympatric taxa as a result of spillover.

Pollination services provided to small and large highbush blueberry fields by wild and managed bees

Summary 1. Plantings of pollinator‐dependent crops vary from large, intensively managed fields to small fields that are managed less intensively, yet there is relatively little information on how pollinator populations and their contribution to crop productivity vary across this gradient. 2. We determined the relative importance of wild bees and managed honey bees Apis mellifera L. for crop pollination in the blueberry Vaccinium corymbosum L. system of Michigan, USA, by comparing bee communities in small, isolated blueberry fields with those in large blueberry fields (stocked with managed honey bee hives) and measuring the difference in yields of open‐pollinated and pollinator‐excluded clusters of flowers. We combined these assessments to calculate the contribution of bees to crop production in this system. 3. Wild bees were the dominant pollinators in small fields, comprising 58% of flower‐visiting bees, whereas 97% of bees in large fields were honey bees. Large fields had four times as many bees visiting flowers than small fields, but only one‐tenth as many bumble bees as small fields. 4. Levels of fruit set exceeded 85% in all fields and were similar between field sizes. Berry weight increased with flower exposure to pollinators and was positively correlated with bee abundance. Berry weights from open‐pollinated flowers were twice as high in large fields compared with small fields. 5. By combining berry weight increases attributable to honey bees and wild bees in blueberry fields with measurements of the bee community adjusted for pollinator efficiency, we calculated the relative contributions of honey bees and wild bees to pollination of Michigan blueberries. We estimate that wild bees provide 82% of the pollination in small fields but only 12% of the total pollination services across this system, mostly through their secondary role in large fields. 6. Synthesis and applications. Wild bees are the primary pollinators of small blueberry fields, but these insects are at low abundance in large fields, perhaps due to a lack of nesting resources or competition for resources with honey bees. Our findings highlight the dependence of commercial fruit producers on honey bees and suggest that increasing the pollination contribution of other bees, particularly bumble bees, in large fields will require that growers adopt wild bee conservation strategies or stock their fields with managed colonies. Quantifying the contributions of managed and wild pollinating bees across the range of crop production scenarios will help to direct development of integrated crop pollination strategies to minimize the risk of pollination deficits affecting food production.

Bee diversity and abundance in an urban setting

AbstractWe assessed bee diversity and abundance in urban areas of Vancouver, British Columbia, Canada, to determine how urban environments can support bees. Habitats examined were community and botanical gardens, urban wild areas, Naturescape flower beds and backyards, and traditional flower beds and backyards. A total of 56 bee species (Hymenoptera), including species of the genera Andrena Fabr. (Andrenidae), Bombus Latr. (Apidae), Osmia Panzer and Megachile Latr. (Megachilidae), and Halictus Latr. and Dialictus Pauly (Halictidae), were collected. Abundance exhibited strong seasonal variation. Wild bees were most abundant during late spring, whereas honey bees peaked at the end of the summer. The most abundant species seen was the managed honey bee Apis mellifera L. (Apidae), followed by wild Bombus flavifrons Cresson. Community and botanical gardens, and plants such as cotoneaster (Cotoneaster Medik. sp.) and blackberry (Rubus discolor Weihe & Nees) (Rosaceae), centaurea (Centaurea L. sp.; Asteraceae), buttercup (Ranunculus L. sp.; Ranunculaceae), and foxglove (Digitalis L. sp.; Scrophulariaceae), had the highest abundance of bees, while bee populations in wild areas were the most diverse. Weeds such as dandelions (Taraxacum officinale G.H. Weber ex Wiggers; Asteraceae) dominated these wild areas and had one of the highest diversities of bee visitors. Traditional flower beds with tulips (Tulipa L. sp.; Liliaceae) and petunias (Petunia Juss. sp.; Solanaceae) had relatively poor diversity and abundance of bees throughout the year. Our study suggests that urban areas have the potential to be important pollinator reservoirs, especially if both bloom and habitat heterogeneity are maintained and enhanced through sustainable urban planning.