Evaluating competition for forage plants between honey bees and wild bees in Denmark

Abstract

A recurrent concern in nature conservation is the potential competition for forage plants between wild bees and managed honey bees. Specifically, that the highly sophisticated system of recruitment and large perennial colonies of honey bees quickly exhaust forage resources leading to the local extirpation of wild bees. However, different species of bees show different preferences for forage plants. We here summarize known forage plants for honey bees and wild bee species at national scale in Denmark. Our focus is on floral resources shared by honey bees and wild bees, with an emphasis on both threatened wild bee species and foraging specialist species. Across all 292 known bee species from Denmark, a total of 410 plant genera were recorded as forage plants. These included 294 plant genera visited by honey bees and 292 plant genera visited by different species of wild bees. Honey bees and wild bees share 176 plant genera in Denmark. Comparing the pairwise niche overlap for individual bee species, no significant relationship was found between their overlap and forage specialization or conservation status. Network analysis of the bee-plant interactions placed honey bees aside from most other bee species, specifically the module containing the honey bee had fewer links to any other modules, while the remaining modules were more highly inter-connected. Despite the lack of predictive relationship from the pairwise niche overlap, data for individual species could be summarized. Consequently, we have identified a set of operational parameters that, based on a high foraging overlap (>70%) and unfavorable conservation status (Vulnerable+Endangered+Critically Endangered), can guide both conservation actions and land management decisions in proximity to known or suspected populations of these species.

Honey bees and climate explain viral prevalence in wild bee communities on a continental scale

“…via shared floral resources 16 , 39 , 42 , 54 , 55 . Even though some solitary bee species are dietary specialists, visiting flowers of only a few plant species, the presence of generalist species such as honey bees connect many species in one network module, increasing the likelihood of viral transmission to all bee species present in the same environment 56 – 60 . However, we found that the relation between viral prevalence in honey bees and wild bees differs between viruses.…”

MetaComNet: A random forest‐based framework for making spatial predictions of plant–pollinator interactions

“…For plants we used the site abundance since we expected a high correlation of bee visitations with plant abundance. Because our aim was not to identify functional traits that determine bee–flower interactions, but to account for floral associations of bees in our models, we assembled a binary network of 207 bee species and 61 plant family interactions based on existing information from interaction records sampled at a greater temporal and spatial extent than our study area (Rasmussen et al., 2021; Wood et al., 2021). This approach provided a more inclusive measure of host plants of bees, closer to the fundamental niche, than what would be achieved from a single survey, such as ours.…”

Preservation methods of honey bee-collected pollen are not a source of bias in ITS2 metabarcoding

“…This is a notable number of taxa, given the temporally limited sampling undertaken herein, with pollen traps activated < 12 h at the single sampling event in August, in Denmark, and at any of the three sampling events in September, in Austria. Yet, this level of richness is supported by reports that honey bees tend to collect greater diversity of pollen later in the season, to compensate for lower availability of mass-blooming sources (Danner et al, 2017;Rasmussen et al, 2021). Despite the high number of visited plants, most pollen was collected from only three species in Austria and four in Denmark, which accounted for 60.2% (14.0) and 54.6% (9.1) of the total abundance in the former and latter country, respectively (median calculated over all samples; Online Resource 8).…”