Pollen analysis of cavity‐nesting bees (Hymenoptera: Anthophila) and their food webs in a city

Abstract

1. Urban areas can host speciose bee communities due partially to the species‐rich combination of both native and alien plant species found in these landscapes. However, in intensively‐constructed zones, it could be expected to record a low plant diversity used by bees because of the high proportion of paved surfaces in these areas. 2. We investigated the influence of urbanisation on the cavity‐nesting bee‐plant community and interaction network structures in a medium‐sized city. The floral diversity used by nesting females in cell provisioning was retrieved from the pollen content obtained from trap‐nests collected in 11 sites located in an urban landscape gradient. 3. Eighty pollen types belonging to 20 families were identified in the 155 pollen samples analysed. At least seven alien plant species were identified in samples from all sampling points. The landscape analysis revealed a positive influence of the proportion of green areas on the pollen type richness, although the null model was also selected as best model. Likewise, all network metrics but connectance were not influenced by any of the landscape variables. 4. Our findings demonstrated that notwithstanding the sampling sites the floral diversity used by bees and the alien pollen type richness were similar. Likewise, the bee‐plant networks were modular, asymmetric, and highly specialised. The positive adaptation that cavity‐nesting bee species present in urban environments and the presence of bee species that can explore a diverse flora may indicate that the local variation in the landscape had little influence on their interactions with plants.

Native and exotic plants play different roles in urban pollination networks across seasons

“…Exotic flowering plants contribute substantially to the supply of nectar and pollen in urban landscapes (Tew et al 2021 ; Casanelles-Abella et al 2022 ), thus potentially supporting pollinator communities by increasing overall resources (Tasker et al 2020 ; Staab et al 2020 ). Indeed, while at the plant community level natives might receive more visits, at the species level some exotics can be very attractive (Lowenstein et al 2019 ; da Rocha-Filho et al 2021 ). In addition, the relative attractiveness of these plants to pollinators may depend on urbanization levels, due to possible effects of urban environmental stressors on pollinator foraging choices (Buchholz and Kowarik 2019 ); and most of the mentioned studies were conducted in private gardens, allotments, and nurseries.…”

First report of a nest of Ceratina (Ceratinula) fioreseana Oliveira (Hymenoptera: Apidae)

“…Indeed, C. oxalidis females containing pollen loads were collected on several flowers belonging to various plant species of different families in southern Brazil (Sakagami & Laroca, 1971). Additionally, in five nests of C. maculifrons collected in an urban area, the residual content had pollen from four plant families, confirming the polylecty of this bee species (Müller & Kuhlmann, 2008;Rocha-Filho et al, 2021). Hence, it is plausible to assume that the use of E. fosbergii pollen for brood cell provisioning may be associated to the very short distance of plant individuals from the nest, likewise P. edulis and M. suaveolens, which were located one to three meters away from the sampling station, ensuring the host female short-distance flights for foraging.…”

“…(Rosaceae) that had already been partly excavated by a female. Dry petioles of C. pachystachya used herein are commonly found in different Brazilian biomes and have been demonstrated to be a useful artificial substrate for nesting Ceratina females, both larger species such as Ceratina (Crewella) maculifrons Smith, 1854 (Rocha-Filho et al, 2021) and minute as C. fioreseana. We also encourage the use of dead branches of Rosa chinensis Jacq.…”

Pollen DNA metabarcoding and related methods in global change ecology: prospects, challenges, and progress

“…Pollen DNA metabarcoding has been used to understand the flexibility of pollinator species dietary niche in response to such changing environmental conditions (Vaudo et al, 2020) and to evaluate and improve conservation efforts (Gresty et al, 2018;Piko et al, 2021). Land-use change can also alter the diversity of resources available to pollinators, with decreased floral richness in agricultural monocultures and context-specific increases or decreases with urbanisation (da Rocha-Filho et al, 2021;Jones, Brennan, et al, 2021;Lucek et al, 2019;Richardson et al, 2021;Samuelson, Gill, & Leadbeater, 2020). Pollen DNA metabarcoding has been used to understand the response of pollinators to resource-rich and resource-poor environments (Casanelles-Abella et al, 2021;Danner et al, 2017;Kaluza et al, 2017;Sponsler et al, 2020;Wilson et al, 2021) and to understand the link between behaviour and pollen intake in resource-poor environments (Nurnberger et al, 2019).…”