Pollen availability for the Horned mason bee (Osmia cornuta) in regions of different land use and landscape structures

Abstract

1. Osmia cornuta is a generalist regarding its habitat requirements and is used for pollination in orchards. The species collects pollen from different plant taxa, but pollen richness and pollen quantity in a nest may be affected by land use and landscape structures.2. The availability of pollen resources for O. cornuta was studied across different land use types (one urban, village-structured, agricultural, and viticultural region each) by pollen analysis in the context of landscape structures.3. In total, 16 pollen types were identified in 1180 brood cells of O. cornuta. On average (± SD), the highest pollen richness per region (n = 4) was found in the viticultural region (4.75 ± 0.96) and the lowest in the agricultural region (1 ± 2). Osmia cornuta collected predominantly pollen from the Sorbus-pollen group, which includes Prunus species. Salix was primarily collected in the village-structured and agricultural regions, and Quercus was frequently found in samples from the viticulture region. The highest mean (± SD) number of brood cells per region (n = 4) was found in the viticulture region (136.35 ± 57.45) and the lowest in the agricultural region (20.25 ± 40.5). Increasing proportions of green areas in urban and village-structured regions affected the pollen richness positively, whereas agricultural areas had a negative impact on pollen richness and the number of brood cells.4. It was concluded that the polylectic O. cornuta uses a wide range of flowering plants dependent on their availability. The maintenance of fruit trees as well as willow and oak trees enhances floral resources qualitatively and quantitatively for O.cornuta specifically in intensively farmed agricultural areas.

Introduced bees (Osmia cornifrons) collect pollen from both coevolved and novel host-plant species within their family-level phylogenetic preferences

“…The use of non-Asian host-plants may be the result of their sampling of the landscape, a by-product of nectar foraging as opposed to active pollen foraging, a dearth of Rosaceae and Fabaceae pollen post-crop bloom in orchards, or that alternative pollen resources are needed in their diet. How bees adjust their foraging behaviour in the absence of preferred resources, or the effects of local floral abundance on species preferences warrants further investigation in more controlled settings (see [22,44]).…”

North-westward range expansion of the bumblebeeBombus haematurusinto Central Europe is associated with warmer winters and niche conservatism

“…Our interpretation is that, since the species nests in tree holes (Reinig 1971), queens are likely dependent on mature trees for nesting, but they can use trees outside forests, while foragers disperse into the surrounding landscape for acquiring resources (Šima et al 2018), even in cities (Teppner 2010). As a matter of fact, this bumblebee visits a large number of flowering species with both simple and complex flower shapes (see results for a list), which hints at a generalist strategy (Kaluza et al 2017; Biella et al 2019a, 2019b; Kratschmer et al 2019). The fact that this species is performing a generalist strategy in foraging and that occurs in heterogeneous macro-habitats likely supported this natural spread (Moreyra & Lozada 2020), as this bee is actually exploiting multiple facets of the new environment.…”

Metabarcoding Analysis of Pollen Species Foraged by Osmia excavata Alfken (Hymenoptera: Megachilidae) in China

“…Wild bees are important pollinators for economic crops and wild plants. They rely on different landscapes to obtain flowering resources and nesting habitats (Kratschmer et al, 2019). In this study, 20 experimental plots in China were set up to collect the beebread of O. excavata.…”