Synergistically positive effects of brick walls and farmlands on Anthophora waltoni populations

Abstract

1 Some wild bees can persist in human-altered habitats in the face of global wild bee decline. To date, however, little is known about why those bees can tolerate human disturbances. Here we hypothesized that wild bees living in human-altered habitats could achieve their nesting resources and floral resources. Moreover, persistent provision of those resources could enhance their populations. 2 The foraging areas of solitary, cavity-nesting bees Anthophora waltoni were determined in two agricultural ecosystems with rich bee populations. The influences of seminatural habitats, nesting resources and farmlands on A. waltoni visit density were assessed by modelling bee density against landscape factors in 17 agricultural ecosystems. Moreover, temporal availabilities of those resources were measured across the last three decades. 3 A. waltoni used vetch fields and field margins, instead of seminatural habitats, as foraging areas. The area of brick walls and the area of farmlands, as well as their temporal increases, synergistically positively influenced A. waltoni visit density on vetch flowers. The percentage of buildings and farmlands increased across the last three decades in spite of a slowdown in 5-year growth of brick walls. 4 The results demonstrated the synergistically positive effects of nesting resources and floral resources, as well as persistent provisions of those resources, on A. waltoni populations in agricultural ecosystems. A. waltoni could live in the human-altered habitats because they persistently achieved their nesting resources and floral resources.

Pollinator responses to farmland habitat features: one-size does not fit all

“…Solitary bee species richness was positively associated with floral species richness within 100m, and this was the only taxonomic group/pollinator metric to respond to a floral metric. The short flight ranges of many solitary bee species means they can be responsive to local conditions and require both nesting and foraging resources to be present within a small area (Zurbuchen et al 2010;Xie et al 2020). The four bee species that responded most to habitat and environmental variation were all small-bodied, solitary species, which further supports the suggestion that solitary species are more reliant on all necessary ecological resources being present at the local scale.…”

“…Fencing off some of these areas would give plants an opportunity to flower, while continuing to allow animals to access some other areas (particularly hedgerow over earthen banks) can help encourage the creation of bare ground for nest sites. Like bare sloped ground, dry stone walls can also offer important opportunities for nesting (Xie et al 2020) and should be valued as such.…”

“…Drainage ditches, field margins, and fields potentially serve as invaluable foraging grounds for pollinators, offering a variety of floral resources essential for their nutrition and energy needs (Potts et al 2010;Wood et al 2015). In contrast, features like stone walls and hedgerows offer structural complexity and a variety of microhabitats, fostering an environment conducive for nesting Xie et al 2020). These elements provide shelter, nesting materials, and suitable substrates for egg-laying for a multitude of pollinator species (Williams & Kremen 2007).…”

Climate Change Influence on the Potential Distribution of Some Cavity-Nesting Bees (Hymenoptera: Megachilidae)

“…The effects of urbanization on wild bees remain unclear in many cases and are not comprehensively understood, and these could offer some benefits such as grasslands and expanded foraging areas [67,68]. There are some examples of anthropogenic influences benefiting bees [69], but, in most cases, habitat loss and fragmentation have far more devastating impacts [70][71][72]. Urbanization negatively affects bee communities through reductions in nesting sites, frequent losses of foraging areas, increased toxicity from wastes and gas fumes, and urban warming [73].…”

Stem-nesting Hymenoptera in Irish farmland: empirical evaluation of artificial trap nests as tools for fundamental research and pollinator conservation

“…In addition to nutritional support, successful pollinator conservation schemes must also consider other components of the pollinator life cycle and ecology, such as provision of larval food plants, shelter, and nesting sites (Potts et al 2005;Kline & Joshi 2020;Requier & Leonhardt 2020). For above-ground cavity nesting bees, man-made structures, such as brickwork or dry-stone walls can provide suitable nesting sites, especially in the absence of natural nesting sites such as hollow stems and tree holes (Xie et al 2020). Additionally, artificial nests (known as 'trap nests' to the scientific community or 'bee hotels' to the general public) can be manufactured or bought from commercial suppliers that mimic natural nesting sites, and provide additional nesting resources for a wide range of cavity-nesting bee and solitary wasp species.…”