Skip to content
Frontiers
Search

Original Research

Frontiers in Bee Science ·

Volume 4 - 2026 | https://doi.org/10.3389/frbee.2026.1744662

Tall trees and exotic herbs identified in pollen and nest materials of seven cavity-nesting solitary bee species in Australia

  • R. S. Wilson1
  • A. Keller2
  • S. D. Leonhardt3
  • T. J. Smith4
  • C. J. Burwell5
  • C. Fuller6
  • A. Shapcott7
  • B. F. Kaluza8
  • H. M. Wallace9*corresponding author
  1. 1School of Environment and Science, Griffith University, Nathan, QLD, Australia
  2. 2Center for Organismic Adaptation, Cellular and Organismic Networks, Ludwig-Maximilians-Universität München, Munich, Germany
  3. 3Department of Life Science Systems, Technical University of Munich, Freising, Germany
  4. 4School of the Environment, University of Queensland, St Lucia, QLD, Australia
  5. 5Biodiversity and Geosciences, Queensland Museum, Brisbane, QLD, Australia
  6. 6Kin Kin Native Bees, Kin Kin, QLD, Australia
  7. 7Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD, Australia
  8. 8Department of Public Technology and Innovation Planning, Fraunhofer Institute for Technological Trend Analysis INT, Euskirchen, Germany
  9. 9School of Biology and Environmental Science, Queensland University of Technology, Brisbane, QLD, Australia
Article metrics0 viewsView details
PDFCiteMetrics

Abstract

Solitary bees are important pollinators yet vulnerable to decline in resource-poor landscapes. Resources for solitary bees may be supplemented by land managers through targeted plantings, however, little is known about the specific plants used by different species. This study identified plants used by seven cavity-nesting solitary bee species in natural and agricultural landscapes over two years by DNA metabarcoding of pollen bread, larvae, frass and nest materials. We sequenced samples from the bee species: Megachile mystacaena (23 nests), Megachile mackayensis (2), Megachile simplex (11), Megachile deanii (3), Hylaeus ruficeps (1), Hylaeus nubilosus (6) and Hyleoides concinna (3). We identified 118 plant taxa from brood provisions (or larvae and frass proxies) and nest materials, however, just 20 taxa accounted for more than 70% of all resources used. Importantly, trees were the most frequently provisioned pollen source for all bees (48 taxa). Introduced plants were used by all bee species studied, even in natural landscapes. Native plants, however, still accounted for more than 50% of relative read abundance for six of seven bee species. Plants identified in nest materials were mostly herbaceous species for leafcutter bees, vines and trees for cellophane bees and parasitic plants (Santalales, “mistletoes”) for resin bees. Agri-environment schemes to support pollinators may be benefit from the inclusion of these taxa or plants with similar characteristics, particularly flowering trees.

Keywords

1 Introduction

Bees are the most economically important pollinators in agroecosystems, yet are especially sensitive to the loss of floral resources (Winfree et al., 2009; Kennedy et al., 2013; Vanbergen et al., 2013). The majority of the world’s 20,500 known bee species are solitary (Michener, 2007; Danforth et al., 2019; Ascher and Pickering, 2020). Solitary bees can have unique adaptations for pollination mutualisms and are equally effective or better pollinators than honey bees for many crops (Minckley and Roulston, 2006; Winfree, 2010). However, some species are particularly vulnerable to decline in homogenous, resource-poor agroecosystems, and loss of these bees can result in less stable pollination services (Kennedy et al., 2013; Vanbergen et al., 2013; Martínez-Núñez et al., 2019). Pressures on bee communities in agroecosystems may be reduced by retaining natural or non-crop vegetation or increasing resource diversity on farm (Kennedy et al., 2013; Goulson et al., 2015; Mallinger et al., 2019; Rollin et al., 2019). Little is known, however, about the specific resource requirements of many species, aside from common and commercial species.

Plants that provide food and nest materials for solitary bees are critical for bee conservation programs. Characteristics of plants (e.g. plant form) used by bees could indicate which plants are useful to functionally similar bees. For example, several species of leafcutter bees (Megachile spp.) prefer leaves from woody trees and shrubs over herbs and vines in India (Kambli et al., 2017) and Canada (MacIvor, 2016), indicating that tree and shrub cover are important to retain for bees that use leaves for nest materials. Other plant characteristics like indigeneity (exotic or native) are also important to consider when selecting forage for bees (Morandin and Kremen, 2013; Pardee and Philpott, 2014). For example, while habitat restoration programs may prefer the use of native plants (Morandin and Kremen, 2013), exotic annual herbs can also provide critical, short-term resources for bees and may be appropriate to plant or retain on farms to supplement crop pollinators (Bretagnolle and Gaba, 2015; Seitz et al., 2020; Jones et al., 2021).

Identifying resources used by solitary bees could help further our understanding of why some species persist in simplified agroecosystems, and which resources could support those that do not, particularly among tropical species. Most research on resource use by bees has been conducted in temperate regions of North America, Europe, and South America (Sobek et al., 2009; Kennedy et al., 2013; Staab et al., 2018; Tonietto and Larkin, 2018). Similar studies in tropical and subtropical agroecosystems are rare (Staab et al., 2018), despite much of the tropics undergoing significant land use change (IPBES, 2019).

In this study, we investigate resource use by seven solitary bee species, including short-tongued Colletidae and long-tongued Megachilidae, in natural and agricultural landscapes in the tropics. We used metabarcoding to examine nest provisions and plant materials used to construct nests, as this technique can enable a comprehensive analysis of plant sources used by bees (Elliott et al., 2021; Wilson et al., 2021). We ask the following research questions: 1) What plants are used by different cavity-nesting solitary bee species in natural and agricultural landscapes for provisioning and nesting materials?; and 2) What are the characteristics (plant form, indigeneity, life cycle) of plants used by cavity-nesting solitary bees in natural and agricultural landscapes?

2 Methods

Plants were identified in the provisions and nest materials of seven bee species: Megachile mystacaena, Megachile mackayensis and Megachile deanii (resin bees); Hylaeus nubilosus, Hylaeus ruficeps and Hyleoides concinna (cellophane bees); and Megachile simplex (a leafcutter bee). These species in particular were included due to sample availability from a previous study that measured trap nest occupation (Wilson et al., 2020).

2.1 Study sites and field collections

We installed trap nests in three orchards and four forests at northern and southern latitudes (−24°38’ to −27°29’ S, 152°06’ to 153°06’ E) of south-east Queensland, Australia in the spring (October) of 2016 (Figure 1A). Sites were categorized as “forest” or “orchard” if they had ≥75% forest or orchard canopy cover respectively within a 500m radius around trap nests. Orchards were a matrix of commercial macadamia (Macadamia integrifolia Maiden and Betche × M. tetraphylla Johnson) and forest fragments. Other sites were open eucalypt forests and woodlands, dominated by an overstory of Eucalyptus and Corymbia species (e.g. Corymbia intermedia, C. trachyphloia, Angophora leiocarpa, Eucalyptus latisinensis, E. exserta, E. tereticornis, E. acmenoides and/or E. pilularis) (Specht, 1970). Plant species identities, abundance and diversity at study sites were estimated from transect surveys (Kaluza et al., 2016, Kaluza et al., 2017).

Schematic of field sample collections. Trap nests were installed in weather-proof units **(A)** in orchards **(B)** and forests **(C)**. Occupied nests were recovered and dissected **(D)** to obtain nest materials **(E)**, frass/larvae proxies **(F)** or pollen **(G)** and then resealed and stored in an emergence box until adults developed **(H)**. Source: Adapted from Wilson et al. (2020), © 2020 by the authors, published under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
Figure 1. Schematic of field sample collections. Trap nests were installed in weather-proof units (A) in orchards (B) and forests (C). Occupied nests were recovered and dissected (D) to obtain nest materials (E), frass/larvae proxies (F) or pollen (G) and then resealed and stored in an emergence box until adults developed (H). Source: Adapted from Wilson et al. (2020), © 2020 by the authors, published under CC BY 4.0.

Four units of timber trap nests were installed per site. Each unit contained five short cavities (100mm long × 6mm diameter) and five long cavities (150mm long × 8mm diameter) drilled into timber blocks lined with removable paper tubes (PaperTunnel™ liners, ©Pollinator Paradise). This design was chosen to allow whole nest management and to attract species that nest above-ground in existing hollow cavities. Trap nest units were checked for occupation every three to four months from February 2017 to December 2018. Occupied trap nests were recovered and replaced with fresh paper tubes each sampling period. Recovered nests (n=590) were placed in fine mesh (organza) bags for transport until dissection. Paper tubes of the recovered nests were dissected and samples taken of nest materials (entire nest cap) and pollen bread (subsample of all pollen balls per nest) or proxies for pollen bread such as bee larvae or frass (one random larva per nest or all frass remaining in nest) (Figure 1D). Samples were stored in 1.5mL Eppendorf Safe-Lock Tubes® and stored at −18 °C until DNA extraction. Dissected nests with larvae or pupae were resealed, transferred to clean organza bags (one nest per bag) and stored together in emergence boxes outdoors (Steckel et al., 2014). All nests were checked monthly for emergents, which were then frozen at −18˚C and pinned for identification (Figure 1). Emergent bees were identified to species or morphospecies by CJB using available taxonomic literature and reference to collections in the Queensland Museum. Cavities in trap nests typically attract bee species from the families Megachilidae and Colletidae which typically encapsulate brood cells and close nests with resin and other plant material (resin or leafcutter bees) or glandular secretions that are cellophane-like when dry (hylaeine bees) (Bell and Cardé, 2013). As such, nests without adult emergents (i.e. dead larvae or pupae) were determined to likely host family or subfamily from nest materials or provisions (e.g. “cellophane” to Hylaeinae; “resin” to Megachilidae).

2.2 DNA library preparation and sequencing

We used DNA metabarcoding to identify plant sources of nest materials and provisions using protocols described by Wilson et al. (2021). Briefly, dry samples of nest materials (n=60), pollen bread (n=32) and pollen proxies (n=10) were individually weighed and subsampled to <0.02g (mean = 0.014g), frozen with liquid nitrogen and disrupted on a TissueLyser II (Qiagen, Germany) with silica-zirconia beads. DNA was then isolated using the Qiagen DNeasy Plant Mini Kit (Qiagen, Germany) according to the manufacturers protocol. Positive (known plant DNA) and negative controls (water) were incorporated from DNA extractions through to sequencing. We amplified DNA using polymerase chain reactions (PCR) with the primer sets rbcL2 (Palmieri et al., 2009) + rbcLaR (Kress and Erickson, 2007) and ITS-S2F (Chen et al., 2010) + ITS4R (White et al., 1990). Primers consisted of a forward and reverse adapter, variable index, pad, link and primer sequence (Kozich et al., 2013; Sickel et al., 2015). Triplicate PCR was performed for each sample and marker using the following conditions: heat activation at 95˚C for 3min; 35 cycles of denaturation at 95˚C for 30sec, annealing at 55˚C (58˚C for rbcL) for 30sec and elongation at 72˚C for 1min; followed by a final extension at 72˚C for 10min, holding at 10˚C until storage. Each reaction contained 5µL KAPA Hifi HotStart ReadyMix (2x) (KAPA Biosystems, MA), 0.6µL each of forward and reverse primer (from 10µM aliquots) and 3.8µL of DNA isolate (or RNAse-free water for negative controls) to a total volume of 10µL. Amplicons were pooled by sample and concentrations normalized using the SequalPrep™ Normalization Plate Kit (Invitrogen Corporation, CA). Samples were quantified with a Quantus™ Fluorometer (Promega Corporation, WI) and the average library size was determined with a High Sensitivity DNA assay on an Agilent 2100 Bioanalyzer (Agilent Technologies, CA). Libraries were pooled equimolarly, denatured with 0.1N NaOH, neutralized with 200mM Tris (pH 7) (Quail et al., 2008), and diluted to 4pM with HT1 buffer. Sequencing was performed on a MiSeq® using the FASTQ Workflow and a 5% PhiX control, with the addition of 3μL of Read 1, Index 1 and Read 2 100μM primers to wells 12, 13 and 14 of the MiSeq v2 500-cycle cartridge (Illumina, CA) for ITS2 or a v3 600-cycle cartridge for rbcL, respectively.

2.3 Data analysis

Raw reads were obtained from the MiSeq and quality-filtered to remove short reads (<100bp) and those with ambiguous base pairs. Forward and reverse reads for ITS2 were joined, however, for rbcL, only forward reads were used due to low overall quality of reverse reads. All reads were assigned to amplicon sequence variants (ASVs), filtered for chimeras and denoised (Edgar, 2010). A reference sequence database of local plant species was created for each marker using the bcdatabaser tool (Keller et al., 2020). Reference sequences were included only for plant species present at study sites and that were between 200bp and 2000bp in length (405 species, 93% of all identified in transects). Each local database consisted of 330 rbcL and 213 ITS2 references from Genbank (Benson et al., 1994), plus rbcL references for 29 plant species sequenced in-house (Pearl et al., 2022). For each marker, ASVs were classified against the appropriate local reference database using global alignments with a threshold of 97% identity. Those ASVs that did not align with local references were then hierarchically classified against a general reference database of all Viridiplantae for rbcL (doi.org/10.5281/zenodo.3339890) or ITS2 (doi.org/10.5281/zenodo.3339029) (Edgar, 2010; Keller et al., 2020). Sample-specific reads were mapped to ASVs to obtain relative read abundance (RRA) estimates (Deagle et al., 2019). All taxonomic assignments were verified by checking their occurrence within the study region using the Atlas of Living Australia (bie.ala.org.au). Assignments to hybrids and taxa not likely to occur in the region (n=32) were reassigned to the next likely taxonomic level (e.g. Crotalaria monophyla to Crotalaria sp.; Listia sp. to Fabaceae sp.). All ASVs that were not assigned to families of vascular plants (e.g. algae) were removed. Taxa identified in blank controls that were present in low abundance in real samples (<1%) were assumed to be contaminants and so also removed (McFrederick and Rehan, 2019).

Data were analyzed separately for rbcL and ITS2 read-matches to account for differences in hierarchical assignments and availability of reference sequences. All analyses were performed in the statistical software ‘R’ (v 3.5.2, R Development Core Team, Austria). The mean (or median) relative read abundance of plant taxa per sample was calculated as a proportion (Deagle et al., 2019). The plant traits “life cycle”, “form” and “indigeneity” were determined through literature review and assigned to each species manually. Traits for taxa not identified to species were unable to be determined and so excluded from trait analysis. Non-metric Multidimensional Scaling (NMDS) in the Phyloseq package was used to compare the composition of plants detected per bee nest with Bray–Curtis distances, two dimensions and up to 999 permutations (McMurdie and Holmes, 2013). We then used permutational multivariate ANOVAs (PERMANOVAs) using the same distance matrices to test the explanatory power of factors on calculated distances (Anderson, 2001). This method is well suited for our data, since it partitions variation in a distribution-free setting within the space of the dissimilarity measure, thus allowing for the non-normal data typical of ecological studies (Anderson, 2014).

3 Results

3.1 Botanical sources of nest materials and provisions

All bee species examined were floral generalists. We identified 118 plant sources of solitary bee provisions and nest materials from 22 orders, 34 families, 67 genera and 69 species across all bee species and samples (Supplementary Materials). Of this, just 20 plant species accounted for more than 70% relative abundance of all resources used (Table 1). Bees in forests used ~5 to 13 plant species, while those in orchards used ~4 to 7 plant species (median richness, Table 2).

Table 1. Plant forms and indigeneity of taxa most commonly used by solitary bees in forest and agricultural landscapes in the subtropics.

FormIndigeneityFamilySpeciesRRArbcLRRAITS2FOOrbcLFOOITS2
HerbIntroducedFabaceaeCrotalaria lanceolata0.000.110%32%
Herb to shrubNAFabaceaeCrotalaria sp.0.030.008%0%
Herb to shrubIntroducedFabaceaeDesmodium sp.0.020.006%0%
NANAFabaceaeFabaceae sp.0.000.020%9%
TreeNativeHimantandraceaeGalbulimima baccata0.030.0030%0%
ParasiteNativeLoranthaceaeAmyema cambagei0.240.0054%0%
ParasiteNativeLoranthaceaeAmyema sp.0.000.070%24%
ParasiteNativeLoranthaceaeAmylotheca dictyophleba0.030.0036%0%
ParasiteNativeLoranthaceaeLoranthaceae sp.0.000.035%24%
HerbIntroducedMalvaceaeModiola caroliniana0.040.1329%38%
HerbIntroducedMalvaceaeSida rhombifolia0.000.030%17%
TreeNativeMyrtaceaeEucalyptus crebra0.000.030%11%
TreeNativeMyrtaceaeEucalyptus racemosa0.000.040%17%
TreeNativeMyrtaceaeEucalyptus sp.0.130.0063%0%
TreeNativeMyrtaceaeLophostemon confertus0.070.0634%17%
TreeNativeMyrtaceaeLophostemon suaveolens0.000.090%44%
VineIntroducedPassifloraceaePassiflora foetida0.080.0034%0%
VineNAPassifloraceaePassiflora sp.0.000.110%44%
TreeNativeProteaceaeMacadamia sp.0.040.0240%13%
HerbNativeSolanaceaeSolanum nodiflorum0.020.0128%29%

Taxa shown have the highest relative read abundance (RRA, measured as mean proportion per sample) and the highest frequency of occurrence (FOO, measured as % of samples that the taxon was detected in) for each marker. Taxa with no applicable form or indigeneity (NA) are unknown species that were classified to genera where different forms and indigeneity may be possible.

Table 2. Observed species richness of plants used by solitary bee species.

Bee species (n)Median plant richness
rbcLITS2
ForestsOrchardsForestsOrchards
Megachile (Callomegachile) mystacaena (23)5 (3–7)–5 (4–8)–
Megachile (Eutricharaea) mackayensis (2)6 (4–11)–7 (5–7)–
Megachile (Eutricharaea) simplex (11)–5.5 (4.25–10.5)–5.5 (4–7.75)
Megachile (Rhodomegachile) deanii (3)6 (4–10)4 (3–10)8 (6–9.5)5 (4–5)
Hylaeus (Euprosopoides) ruficeps (1)7 (7–7)–8 (8–8)–
Hylaeus (Hylaeorhiza) nubilosus (6)13 (12.5–13.5)7.5 (6.75–8.25)6 (4.5–7.5)5 (5–5)
Hyleoides concinna (3)8 (5–12)–5 (5–5)–

Values are median (interquartile range) number of plant species identified per sample, per marker, in forests and orchards. Dashes (–) indicate bee species absent from orchards or forests. Values next to species names (n) indicate the number of nests sampled. Further information about the bee species studied (abundance in forests and orchards, number of brood cells per nest and nesting behavior) is provided in Wilson et al. (2020).

The composition of plant resources used varied with bee species (R2rbcL=0.31, P = 0.001, stress=0.13; R2ITS2 = .25, P = 0.001; stress=0.18) and land use (R2rbcL=0.08, P = 0.003; Figure 2), but not season (R2rbcL=0.03, P = 0.253; R2ITS2 = .01, P = 0.685). Plants used in orchards were generally a subset of those species used in forests (Figure 2).

Ordination of Bray–Curtis distance showing differences in community composition of plant species used by cellophane bees (circles), leafcutter bees (triangles) and resin bees (squares) in forests (green) and orchards (yellow). Each point represents combined resources for one nest in one season in one year. Plants used in orchards are generally a subset of those used in forests.
Figure 2. Ordination of Bray–Curtis distance showing differences in community composition of plant species used by cellophane bees (circles), leafcutter bees (triangles) and resin bees (squares) in forests (green) and orchards (yellow). Each point represents combined resources for one nest in one season in one year. Plants used in orchards are generally a subset of those used in forests.

We identified key plants used for multiple purposes and by multiple bee taxa (Figure 3). For example, Modiola caroliniana (Malvaceae) and Passiflora foetida (Passifloraceae) were identified in brood provisions and all nest material types (Figure 3). Similarly, Lophostemon suaveolens, L. confertus and Eucalyptus racemosa (Myrtaceae) were identified in pollen, resin and cellophane samples (Figure 3). Importantly, some plants were only used or available in forests but not orchards (e.g. Melaleuca spp.) and some only in orchards but not forests (e.g. Rubus spp.) (Figure 3). Overlap was observed between plant sources of pollen samples and proxies for pollen samples (larvae, frass), indicating that these sample types may be used in the absence of pollen to ascertain provisions (Figure 3).

Plant taxa identified by land use (forest, orchard) and sample type. Data are mean proportion of plant taxa identified per sample, per marker. Multiple colours per bar show that some plants are multi-purpose (i.e. used for provisions and one or more nest materials). Overlap between plant sources of pollen samples and proxies for pollen samples (larvae, frass), indicates that these sample types can be used in the absence of pollen to ascertain provisions. Some plants are used (or available) in forests but not orchards (e.g. *Melaleuca* spp.), some in orchards but not forests (e.g. *Rubus* spp.) and many in both land uses. Data are combined for all solitary bee species.
Figure 3. Plant taxa identified by land use (forest, orchard) and sample type. Data are mean proportion of plant taxa identified per sample, per marker. Multiple colours per bar show that some plants are multi-purpose (i.e. used for provisions and one or more nest materials). Overlap between plant sources of pollen samples and proxies for pollen samples (larvae, frass), indicates that these sample types can be used in the absence of pollen to ascertain provisions. Some plants are used (or available) in forests but not orchards (e.g. Melaleuca spp.), some in orchards but not forests (e.g. Rubus spp.) and many in both land uses. Data are combined for all solitary bee species.

Resin bees (M. mystacaena, M. mackayensis and M. deanii) used 93 plant taxa across all specimens and sites (Supplementary Materials), particularly Amyema spp. (mean proportion 2–55%, Loranthaceae), M. caroliniana (4–18%) and Passiflora spp. (1–11%) for nest materials; and L. confertus (8–18%) and Crotalaria spp. (1–29%, Fabaceae) for pollen. The cellophane bees (Hylaeus nubilosus, H. ruficeps and Hyleoides concinna) frequently provisioned pollen from Myrtaceae (13 out of 54 taxa found for both pollen and nest materials) and in high abundances (2 to 63%) – particularly Eucalyptus tereticornis, E. racemosa, E. crebra, L. confertus, L. suaveolens and Backhousia sp. (Supplementary Materials). Plant materials identified in cellophane bee nest caps were mostly M. caroliniana (10–41%) and Passiflora spp. (1–20%) (Supplementary Materials). Leafcutter bee (M. simplex) nest materials were sourced from 35 plant taxa, particularly Passiflora spp. (10–48%), M. caroliniana (11–16%), Sida spp. (1–10%, Malvaceae) and Solanum spp. (Solanaceae, 4–7%); and pollen was sourced from 23 taxa, mostly Desmodium uncinatum (Fabaceae, 1–16%), Eucalyptus spp. (7–12%, Myrtaceae) and Macadamia sp. (Proteaceae, 1–9%) (Supplementary Materials).

3.2 Characteristics of botanical resources

Introduced plants were used by all bee species studied. Of the 118 plant taxa identified, 70 were native to the study region, 26 were introduced and 22 were undetermined. Plants with undetermined indigeneity included taxa that were only assigned to genus or higher taxonomic levels which are known to have both native and introduced species in Australia. The median relative read abundance of introduced plants varied greatly between bee species, from very low (e.g. 1–16% for M. mackayensis) to very high (39–86% for H. concinna) (Table 3). Native plants, however, still accounted for more than 50% of relative read abundance for six of seven bee species.

Table 3. Median proportion (interquartile range) of introduced plants identified in provisions and nest materials of solitary bees, per marker.

Bee speciesMedian proportion of introduced plants
ITS2rbcL
Megachile (Callomegachile) mystacaena0.35 (0.01, 0.73)0.00 (0.00, 0.03)
Megachile (Eutricharaea) mackayensis0.16 (0.05, 0.45)0.01 (0.00, 0.28)
Megachile (Eutricharaea) simplex0.43 (0.08, 0.55)0.47 (0.13, 0.75)
Megachile (Rhodomegachile) deanii0.49 (0.06, 0.57)0.08 (0.01, 0.22)
Hylaeus (Euprosopoides) ruficeps0.22 (0.22, 0.22)0.00 (0.00, 0.00)
Hylaeus (Hylaeorhiza) nubilosus0.17 (0.07, 0.40)0.14 (0.00, 0.40)
Hyleoides concinna0.86 (0.43, 0.88)0.39 (0.19, 0.44)

The proportion of resources used by plant form shows that trees are the most provisioned pollen source for all bees studied, particularly the cellophane bees (Figure 4). Leafcutter bees also provision pollen from shrubs and herbaceous plants, as do resin bees (Figure 4). In contrast to pollen sources, the most common plant form for nest materials was herbaceous plants, particularly for leafcutter bees (Figure 4). Vines and trees were also commonly used plant forms for cellophane and resin bee nests (Figure 4). Surprisingly, parasitic plants (Santalales, “mistletoes”) were the most frequently used resource to construct nests for resin bees (Figure 4). Most taxa identified were perennials (94 of 118 taxa), except for herbaceous plants, which were mostly annuals (13 taxa) (Supplementary Materials). The introduced annuals Modiola caroliniana (Malvaceae) and Crotalaria lanceolata (Fabaceae; Table 1) were used by all bee groups studied. Similarly, the trees Eucalyptus racemosa, Lophostemon confertus and L. suaveolens were also used by all bee groups (Myrtaceae; Table 1).

Plant forms used by solitary bees for pollen and nest materials. **(A)** shows median proportion of plant forms found in each sample of pollen. **(B)** shows median proportion of plant forms found in each sample of nest material. Plant form was determined from the literature and assigned to each species manually. Note that the plant form categories “Herb to shrub” (n=5) and “Shrub to tree” (n=3) are excluded for visual ease (see **Supplementary Materials**) and the category “Grass” includes grasses and sedges. .
Figure 4. Plant forms used by solitary bees for pollen and nest materials. (A) shows median proportion of plant forms found in each sample of pollen. (B) shows median proportion of plant forms found in each sample of nest material. Plant form was determined from the literature and assigned to each species manually. Note that the plant form categories “Herb to shrub” (n=5) and “Shrub to tree” (n=3) are excluded for visual ease (see Supplementary Materials) and the category “Grass” includes grasses and sedges. .

4 Discussion

This study identified key sources and characteristics of plants used by solitary bees for brood provisions and nest materials in natural and agricultural landscapes. Several plants were identified as key sources of both nest provisions and materials for multiple bee species (Modiola caroliniana, Passiflora foetida, Lophostemon suaveolens, L. confertus and Eucalyptus racemosa). Of the 118 plant taxa identified, most were native, perennial shrubs or trees (55 taxa). Trees were the most common source of pollen, whereas herbaceous plants (mostly annuals) were the most common source of nest materials. Introduced plants (26 taxa) were used by all bee species studied, even in natural landscapes (up to 86% for one bee species).

4.1 Botanical sources of nest materials and provisions

The composition of plants used varied significantly with bee species and landscape. Plants used by bees in orchards were mostly a subset of those in forests, suggesting that bees in forests used or had access to a wider range of resources. While there was much overlap, some plants were only identified in nests from one of the two land uses (e.g. Melaleuca spp. trees in forests and Rubus spp. shrubs in orchards), despite being present in both landscapes. Furthermore, more plant taxa were identified in forest-dwelling bee nests (median ~5 to 13 species) compared to those in orchards (~4 to 7 species), including the two bee species present in both land uses (M. deanii and H. nubilosus). As such, at least some of the differences in bee resource-use between landscapes is likely due to the processes of landscape simplification (i.e. reducing the overall number of resources available to and or used by solitary bees) (Vanbergen et al., 2013; Goulson et al., 2015; Wood et al., 2016).

Bee species with high abundance in the region may be less susceptible to changes in resource availability. Records from the Atlas of Living Australia (2026) indicate that 164 native bee species (excluding social species) exist in our study region around Bundaberg in the north and the Sunshine Coast in the south. Four of the seven species included in our study are common in the region and across the mainland of Australia (H. nubilosus, H. concinna, M. mystaceana and M. simplex). There are no records of H. ruficeps in the study region, however, this bee is commonly recorded elsewhere in Queensland and other states. Similarly, records of M. deanii are less common in our study region (4 of 189 nationwide), however, it’s propensity to steal wax from other species and construct nests in manmade objects indicates that the species is very adaptable (Arcaro and Houston, 2024). The resin bee M. Mackayensis is particularly rare. Records show limited but consistent recent detections of M. Mackayensis, with four records between 1888 and 1957 then five records between 2016 and 2025, all from Queensland, New South Wales and Western Australia. Other trap-nest studies have only detected M. Mackayensis in the understorey and canopy of densely forested habitats, which may be why sightings are particularly rare (Wilson et al., 2020; Morris et al., 2015).

Similarities in the resources used by bees present in both natural and agricultural landscapes may indicate plants important for their persistence. For example, six pollen sources, mostly members of Passifloraceae, were used by M. deanii in forests and orchards; and six members of Myrtaceae were used by H. nubilosus as major pollen sources in both landscapes. Interestingly, the overlapping plants between landscapes used by these bees are all tree and vine species, supporting the idea that agricultural landscapes with at least partial complexity (i.e. patches of forest or diverse plantings) are important for sustaining bee populations (Winfree, 2010; Wood et al., 2016; Rollin et al., 2019; Wilson et al., 2021; Cannizzaro et al., 2022). Agricultural landscapes with high functional diversity (e.g. plant forms) or plant diversity are associated with the persistence of generalist bees (Wood et al., 2016) more than an increase in the area of natural habitat alone (Rollin et al., 2019). Continued use of trees and vines by bees in simplified agricultural landscapes suggests that forests or other areas of natural habitat with high plant diversity should be conserved to sustain bees in both natural and agricultural landscapes (Winfree, 2010).

Some of the key botanical sources we identified, such as M. caroliniana (Malvaceae) and P. foetida (Passifloraceae), and myrtaceous trees are taxonomically similar to those used by congeneric bees in other countries. For example, the frequent use of Myrtaceae by cellophane bees is also seen in four Hylaeus species in Hawai’i (Miller et al., 2015). We would expect Hylaeus bees and many other colletids to be using Myrtaceae as the diversification of Colletidae and Myrtaceae in Australia are thought to be tightly linked (Houston et al., 1993; Phillips et al., 2010; Slattery et al., 2023). Other findings, however, are in contrast to those in similar regions, such as the frequent use of Passifloraceae rather than Fabaceae for nest materials by leafcutter bees (Kambli et al., 2017). The use of similar materials from a variety of plants in nest construction underlies the range expansion and diversification among leafcutters and other bees in Megachilidae (Litman et al., 2011). Similarly, solitary bee visits to flowers of Loranthaceae have been recorded (Robertson et al., 2005), however, this is the first time, to our knowledge, that mistletoes have been identified as the main source of nest materials for resin bees. It is unlikely that these are pollen contaminants from provisioning foraging bouts, as the greater median proportion of mistletoes in nest caps (approx. 0.87) compared to pollen bread (0.05) suggests the collection is intentional. The detection of any plant material in hylaeine nest caps has also not been reported elsewhere to our knowledge.

Importantly, we identified the same plants from larvae and frass as those found in pollen bread for each bee species, thus demonstrating that such samples can be used as proxies for diet analyses with DNA metabarcoding. Bee–plant interactions have also been detected via metabarcoding swabs of solitary bee nests (Sickel et al., 2023) and a similar approach has been used on whole bee, pupal and larval specimens to study microbiomes and pathogens (e.g. Erban et al., 2017; Keller et al., 2018; Voulgari-Kokota et al., 2020).

4.2 Characteristics of botanical resources

Tree species were the most commonly provisioned pollen source of all bees studied. Traditionally, bee visits to tall trees have been difficult to observe due to the difficulty involved in sampling the canopy (i.e. with climbing ropes or flight-intercept traps) (Ramalho, 2004; Ulyshen et al., 2010). With DNA metabarcoding, however, we were able to quantify bee use of 43 tree species – half of which grow to heights greater than 20m. For example, bees used Polyscias elegans (20–30m, Araliaceae), Gmelina leichhardtii (15–60m, Lamiaceae), Syncarpia glomulifera (25–60m, Myrtaceae) and Eucalyptus pilularis (40–70m, Myrtaceae) (Floyd, 1990; Brooker and Kleinig, 1999; Boland et al., 2006). This study adds to emerging molecular evidence that a disproportionate amount of bee-collected pollens come from trees (Somme et al., 2016; Donkersley, 2019; Voulgari-Kokota et al., 2019; Vaudo et al., 2020; Cannizzaro et al., 2022). This information is important for the design of revegetation programs or agri-environment schemes that currently focus on flower-strip plantings as inter-crop forage for bees (Wood et al., 2017; Gresty et al., 2018). Plantings or conservation of established trees as inter-crop forage could focus on species that fulfill multiple resource requirements such as Lophostemon suaveolens, L. confertus and Eucalyptus racemosa (Myrtaceae), which are native to the study region and were identified in pollen, resin and cellophane samples.

Introduced plants (26 taxa) were used by all bee species studied. The proportion of introduced plant use varied greatly between bee species, from very low (e.g. 1–16% for M. mackayensis) to very high (39–86% for H. concinna). This is the first record to our knowledge of exotic plant use by these species. Native plants (70 taxa), however, still accounted for more than 50% of relative read abundance for six of seven bee species. The most commonly used native plants were all in the family Myrtaceae: L. suaveolens, L. confertus, E. racemosa, E. tereticornis, E. crebra, Melaleuca spp., and Backhousia species. Native bee preferences for mostly native plants over co-occurring weedy or exotic plants has also been observed in restored agricultural areas (Morandin and Kremen, 2013) and urban gardens (Pardee and Philpott, 2014). Bee use of introduced plants is known to increase with abundance of individual introduced plants in agricultural and semi-natural landscapes (Williams et al., 2011) and in times when native plants are less likely to be flowering, such as early or late in a bees’ flying season (Seitz et al., 2020). As fast-growing, early- or late-blooming, and often nutritious species, introduced annuals may fill temporal gaps in flowering resource availability or reward where mature, native flowers are lacking (Mach and Potter, 2018; Russo et al., 2019). Land managers can thus easily provide forage for solitary bees by either managing existing populations of introduced plants (e.g. by mowing before seed set) or including selected species in strip plantings between crop rows or human-dominated landscapes (Lerman et al., 2018; Seitz et al., 2020). Selection of exotic plant species must exclude those that compete with endemic plants such as supergeneralist perennials (Vila et al., 2009; Stouffer et al., 2014; Jones et al., 2021). As such, two introduced plants that may be of interest to land managers seeking forage for bees are Modiola caroliniana and Crotalaria lanceolata. These plants were used by all bee groups studied and are present in almost all tropical and subtropical continents (Jacobi et al., 2005; Barkley et al., 2006). Both plants are also annual herbs that typically colonize disturbed sites, and so pose little risk of invading undisturbed areas (Davis and Thompson, 2000).

Herbaceous plants were the most common source of nest materials for leafcutter (Megachile (Eutricharaea)) and cellophane (Hylaeinae) bees. Microscopic examination of the cell linings of other species of Hylaeus (Hylaeinae) showed the presence of fiber-like strands embedded in a solid matrix, suggesting that their linings are comprised of two different components (Espelie et al., 1992). Many other bees are known to mix waxy secretions (from exocrine glands) with plant materials before using them in nest construction (e.g. stingless bees, Meliponini) (Wille, 1983). Our results suggest that hylaeine bees mix their own exocrine secretions with plant sources. Personal observation of H. nubilosus constructing nests suggests this species does add plant material (human-made sawdust or frass from wood-boring insects – a source of cellulose) to their secretions when sealing or “capping” a nest entrance, however, they appear to use only secretions to line or divide brood cells (RW; CF; TS personal observations).

Surprisingly, parasitic plants (Santalales, “mistletoes”) were the most frequently used resource to construct nests by resin bees. Possible source materials may be the glue-like secretions of haustorial hairs, used by all parasitic plants to attach to their host (Yoshida et al., 2016), or wax from the cuticles of laminar surfaces (Wollenweber et al., 2000).

5 Conclusion

This study found that native shrubs or trees and introduced herbs are key plant sources of nest provisions and materials for cavity-nesting solitary bees in natural and agricultural landscapes. Plants used in both orchards and forests by the same bee taxa were all tree and vine species, supporting the idea that habitat complexity is important for sustaining bee populations in agricultural landscapes. Furthermore, introduced plants were used for pollen and/or nest materials by all bee species studied, probably due to their ubiquity in both landscapes, and may be crucial for filling temporal/nutritional gaps in resource availability. However native plants accounted for more than 50% of relative read abundance for six of seven bee species. Based on these findings, we recommend providing forage for bees by retaining or planting patches of complex habitat (i.e. with trees, shrubs and vines) and managing herbaceous weeds and mistletoes in ways that reduce spread while retaining forage during periods of resource scarcity.

Generative AI statement

The author(s) declared that generative AI was not used in the creation of this manuscript.

Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/frbee.2026.1744662/full#supplementary-material

Supplementary material Supplementary material at the source

Supplementary material Supplementary material at the source

Footnotes

Edited by: Filitsa Karamaouna, Benaki Phytopathological Institute, Greece

Reviewed by: Ekaterina Kozuharova, Medical University, Bulgaria

Ken-Ichi Harano, Tamagawa University, Japan

Statements

Conflict of interest

The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

The author HW declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.

Funding

The author(s) declared that financial support was received for this work and/or its publication. The following provided funding for this research project: Genecology Research Centre, the University of the Sunshine Coast and the Friends of the Maroochy Regional Bushland Botanic Gardens.

Data availability

The data presented are deposited in the Zenodo respository, accession number 10.5281/zenodo.18932434.

Ethics approval

The manuscript presents research on animals that do not require ethical approval for their study.

Author contributions

RW: Conceptualization, Formal Analysis, Writing – review & editing, Data curation, Investigation, Methodology, Writing – original draft, Validation, Visualization. AK: Conceptualization, Formal Analysis, Investigation, Methodology, Writing – review & editing. SL: Conceptualization, Formal Analysis, Methodology, Writing – review & editing. TS: Methodology, Writing – review & editing, Data curation, Investigation. CB: Formal Analysis, Investigation, Methodology, Writing – review & editing, Data curation. CF: Data curation, Investigation, Methodology, Writing – review & editing. AS: Data curation, Methodology, Writing – review & editing, Supervision. BK: Methodology, Writing – review & editing, Conceptualization, Resources. HW: Conceptualization, Methodology, Writing – review & editing, Formal Analysis, Funding acquisition, Investigation, Project administration, Supervision.

Acknowledgements

We thank the Australian Government Research Training Program and the Rotary Clubs of the Sunshine Coast for scholarships. Special thanks to all the landholders whom kindly hosted our bee hotels for two years. We acknowledge Brittany Elliott, Chris Cannizarro, Ryan Newis and Wiebke Kaemper for their help in the field and lab. We also thank Professor David Watson for sharing his knowledge of parasitic plant ecology.

References

  1. Anderson M. J. (2001). A new method for non-parametric multivariate analysis of variance. Austral Ecol. 26, 32 – 46.
  2. Anderson M. J. (2014). Permutational multivariate analysis of variance (PERMANOVA) (Wiley StatsRef). Available online at: https://onlinelibrary.wiley.com/doi/10.1002/9781118445112.stat07841.
  3. Arcaro F., Houston T. (2024). MegaChile (RhodomegaChile) deanii, a resin bee that steals beeswax—newly recorded from south-western Australia. Aust. Entomologist 51, 161 – 168. doi:, PMID: doi:10.3316/informit.T2025030800005801242203033
  4. Ascher J. S., Pickering J. (2020). Discover Life bee species guide and world checklist (Hymenoptera: Apoidea: Anthophila). Available online at: http://www.discoverlife.org/mp/20q?guide=Apoidea_species (Accessed October 7, 2025).
  5. Atlas of Living Australia Occurrence records. Available online at: https://biocache.ala.org.au/occurrences/search (Accessed January 29, 2026).
  6. Barkley T. M., Brouillet L., Jeude H., Strother J., Gandhi K., Kiger R.. (2006). Flora of north america north of Mexico Vol. 20 (New York: Oxford University Press).
  7. Bell W. J., Cardé R. T. (2013). Chemical ecology of insects (New York: Springer).
  8. Benson D. A., Boguski M., Lipman D. J., Ostell J. (1994). GenBank. Nucleic Acids Res. 22, 3441 – 3444. doi:, PMID: doi:10.1093/nar/22.17.3441
  9. Boland D. J., Brooker M. I. H., McDonald M. W., Chippendale G. M. (2006). Forest trees of Australia (Clayton: CSIRO Publishing).
  10. Bretagnolle V., Gaba S. (2015). Weeds for bees? A review. Agron. Sustain. Dev. 35, 891 – 909. doi:, PMID: doi:10.1007/s13593-015-0302-5
  11. Brooker I., Kleinig D. (1999). Field guide to eucalypts (Hawthorn: Bloomings Books).
  12. Cannizzaro C., Keller A., Wilson R. S., Elliott B., Newis R., Ovah R.. (2022). Forest landscapes increase diversity of honeybee diets in the tropics. For. Ecol. Manage. 504, 119869. doi:, PMID: doi:10.1016/j.foreco.2021.119869
  13. Chen S., Yao H., Han J., Liu C., Song J., Shi L.. (2010). Validation of the ITS2 region as a novel DNA barcode for identifying medicinal plant species. PLoS One 5, e8613. doi:, PMID: doi:10.1371/journal.pone.0008613
  14. Danforth B. N., Minckley R. L., Neff J. L., Fawcett F. (2019). The solitary bees: biology, evolution, conservation (Princeton: Princeton University Press).
  15. Davis M. A., Thompson K. (2000). Eight ways to be a colonizer; two ways to be an invader: a proposed nomenclature scheme for invasion ecology. Bull. Ecol. Soc. America 81, 226 – 230.
  16. Deagle B. E., Thomas A. C., McInnes J. C., Clarke L. J., Vesterinen E. J., Clare E. L.. (2019). Counting with DNA in metabarcoding studies: How should we convert sequence reads to dietary data ? Mol. Ecol. 28, 391 – 406. doi:, PMID: doi:10.1111/mec.14734
  17. Donkersley P. (2019). Trees for bees. Agriculture Ecosyst. Environ. 270, 79 – 83. doi:, PMID: doi:10.1016/j.agee.2018.10.024
  18. Edgar R. C. (2010). Search and clustering orders of magnitude faster than BLAST. Bioinformatics 26, 2460 – 2461. doi:, PMID: doi:10.1093/bioinformatics/btq461
  19. Elliott B., Wilson R., Shapcott A., Keller A., Newis R., Cannizzaro C.. (2021). Pollen diets and niche overlap of honey bees and native bees in protected areas. Basic Appl. Ecol. 50, 169 – 180. doi:, PMID: doi:10.1016/j.baae.2020.12.002
  20. Erban T., Ledvinka O., Kamler M., Nesvorna M., Hortova B., Tyl J.. (2017). Honeybee (Apis mellifera)-associated bacterial community affected by American foulbrood: detection of Paenibacillus larvae via microbiome analysis. Sci. Rep. 7, 1 – 10. doi:, PMID: doi:10.1038/s41598-017-05076-8
  21. Espelie K., Cane J. H., Himmelsbach D. (1992). Nest cell lining of the solitary beeHylaeus bisinuatus (Hymenoptera: Colletidae). Experientia 48, 414 – 416. doi:, PMID: doi:10.1007/BF01923446
  22. Floyd A. G. (1990). Australian rainforests in new south wales Vol. 2 (Sydney: Surrey Beatly and Sons).
  23. Goulson D., Nicholls E., Botías C., Rotheray E. L. (2015). Bee declines driven by combined stress from parasites, pesticides, and lack of flowers. Science 347, 1255957. doi:, PMID: doi:10.1126/science.1255957
  24. Gresty C. E. A., Clare E., Devey D. S., Cowan R. S., Csiba L., Malakasi P.. (2018). Flower preferences and pollen transport networks for cavity-nesting solitary bees: Implications for the design of agri-environment schemes. Ecol. Evol. 8, 7574 – 7587. doi:, PMID: doi:10.1002/ece3.4234
  25. Houston T., Lamont B., Radford S., Errington S. (1993). Apparent mutualism between Verticordia nitens and V-aurea (Myrtaceae) and their oil-ingesting bee pollinators (Hymenoptera, Colletidae). Aust. J. Bot. 41, 369 – 380. doi:, PMID: doi:10.1071/BT9930369
  26. IPBES (2019). Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Eds. Díaz S., Settele J., Brondizio E. S., Ngo H. T., Guèze M., Agard J., Arneth A., Balvanera P., Brauman K. A., Butchart S. H. M., Chan K. M. A., Garibaldi L. A., Ichii K., Liu J., Subramanian S. M., Midgley G. F., Miloslavich P., Molnár Z., Obura D., Pfaff A., Polasky S., Purvis A., Razzaque J., Reyers B., Chowdhury R. R., Shin Y. J., Visseren-Hamakers I. J., Willis K. J., Zayas C. N. (Bonn: IPBES Sectretariat).
  27. Jacobi C. M., Ramalho M., Silva M. (2005). Pollination biology of the exotic rattleweed crotalaria retusa L.(Fabaceae) in NE Brazil 1. Biotropica 37, 357 – 363. doi:, PMID: doi:10.1111/j.1744-7429.2005.00047.x
  28. Jones L., Brennan G. L., Lowe A., Creer S., Ford C. R., de Vere N. (2021). Shifts in honeybee foraging reveal historical changes in floral resources. Commun. Biol. 4, 1 – 10. doi:, PMID: doi:10.1038/s42003-020-01562-4
  29. Kaluza B. F., Wallace H., Heard T. A., Klein A. M., Leonhardt S. D. (2016). Urban gardens promote bee foraging over natural habitats and plantations. Ecol. Evol. 6, 1304 – 1316. doi:, PMID: doi:10.1002/ece3.1941
  30. Kaluza B. F., Wallace H., Keller A., Heard T. A., Jeffers B., Drescher N.. (2017). Generalist social bees maximize diversity intake in plant species-rich and resource-abundant environments. Ecosphere 8, e01758. doi:, PMID: doi:10.1002/ecs2.1758
  31. Kambli S. S., Aiswarya M., Manoj K., Varma S., Asha G., Rajesh T.. (2017). Leaf foraging sources of leafcutter bees in a tropical environment: implications for conservation. Apidologie 48, 473 – 482. doi:, PMID: doi:10.1007/s13592-016-0490-2
  32. Keller A., Brandel A., Becker M. C., Balles R., Abdelmohsen U. R., Ankenbrand M. J.. (2018). Wild bees and their nests host Paenibacillus bacteria with functional potential of avail. Microbiome 6, 1 – 10. doi:, PMID: doi:10.1186/s40168-018-0614-1
  33. Keller A., Hohlfeld S., Kolter A., Schultz J., Gemeinholzer B., Ankenbrand M. J. (2020). BCdatabaser: on-the-fly reference database creation for (meta-)barcoding. Bioinformatics 36, 2630 – 2631. doi:, PMID: doi:10.1093/bioinformatics/btz960
  34. Kennedy C. M., Lonsdorf E., Neel M. C., Williams N. M., Ricketts T. H., Winfree R.. (2013). A global quantitative synthesis of local and landscape effects on wild bee pollinators in agroecosystems. Ecol. Lett. 16, 584 – 599. doi:, PMID: doi:10.1111/ele.12082
  35. Kozich J. J., Westcott S. L., Baxter N. T., Highlander S. K., Schloss P. D. (2013). Development of a dual-index sequencing strategy and curation pipeline for analyzing amplicon sequence data on the MiSeq Illumina sequencing platform. Appl. Environ. Microbiol. 79, 5112 – 5120. doi:, PMID: doi:10.1128/AEM.01043-13
  36. Kress W. J., Erickson D. L. (2007). A two-locus global DNA barcode for land plants: the coding rbcL gene complements the non-coding trnH-psbA spacer region. PLoS One 2, e508. doi:, PMID: doi:10.1371/journal.pone.0000508
  37. Lerman S. B., Contosta A. R., Milam J., Bang C. (2018). To mow or to mow less: Lawn mowing frequency affects bee abundance and diversity in suburban yards. Biol. Conserv. 221, 160 – 174. doi:, PMID: doi:10.1016/j.biocon.2018.01.025
  38. Litman J. R., Danforth B. N., Eardley C. D., Praz C. J. (2011). Why do leafcutter bees cut leaves? New insights into the early evolution of bees. Proc. R. Soc. B 278, 3593 – 3600. doi:, PMID: doi:10.1098/rspb.2011.0365
  39. Mach B. M., Potter D. A. (2018). Quantifying bee assemblages and attractiveness of flowering woody landscape plants for urban pollinator conservation. PLoS One 13, e0208428. doi:, PMID: doi:10.1371/journal.pone.0208428
  40. MacIvor J. S. (2016). DNA barcoding to identify leaf preference of leafcutting bees. R. Soc. Open Sci. 3, 150623. doi:, PMID: doi:10.1098/rsos.150623
  41. Mallinger R. E., Franco J. G., Prischmann-Voldseth D. A., Prasifka J. R. (2019). Annual cover crops for managed and wild bees: Optimal plant mixtures depend on pollinator enhancement goals. Agriculture Ecosyst. Environ. 273, 107 – 116. doi:, PMID: doi:10.1016/j.agee.2018.12.006
  42. Martínez-Núñez C., Manzaneda A. J., Lendínez S., Pérez A. J., Ruiz-Valenzuela L., Rey P. J. (2019). Interacting effects of landscape and management on plant–solitary bee networks in olive orchards. Funct. Ecol. 33, 2316 – 2326. doi:, PMID: doi:10.1111/1365-2435.13465
  43. McFrederick Q. S., Rehan S. M. (2019). Wild bee pollen usage and microbial communities co-vary across landscapes. Microbial Ecol. 77, 513 – 522. doi:, PMID: doi:10.1007/s00248-018-1232-y
  44. McMurdie P. J., Holmes S. (2013). phyloseq: an R package for reproducible interactive analysis and graphics of microbiome census data. PLoS One 8, e61217. doi:, PMID: doi:10.1371/journal.pone.0061217
  45. Michener C. D. (2007). The bees of the world (Baltimore, Maryland: John Hopkins University Press).
  46. Miller A. E., Brosi B. J., Magnacca K., Daily G. C., Pejchar L. (2015). Pollen carried by native and nonnative bees in the large-scale reforestation of pastureland in hawai ‘i: implications for pollination1. Pacific Sci. 69, 67 – 79. doi:, PMID: doi:10.2984/69.1.5
  47. Minckley R. L., Roulston T. (2006). “ Incidental mutualisms and pollen specialization among bees,” in Plant-pollinator interactions: from specialization to generalization. Eds. Waser N. M., Ollerton J. (University of Chicago Press, Chicago, IL), 69 – 98.
  48. Morandin L. A., Kremen C. (2013). Bee preference for native versus exotic plants in restored agricultural hedgerows. Restor. Ecol. 21, 26 – 32. doi:, PMID: doi:10.1111/j.1526-100X.2012.00876.x
  49. Morris R. J., Sinclair F. H., Burwell C. J. (2015). Food web structure changes with elevation but not rainforest stratum. Ecography 38, 792 – 802. doi:, PMID: doi:10.1111/ecog.01078
  50. Palmieri L., Bozza E., Giongo L. (2009). Soft fruit traceability in food matrices using real-time PCR. Nutrients 1, 316 – 328. doi:, PMID: doi:10.3390/nu1020316
  51. Pardee G. L., Philpott S. M. (2014). Native plants are the bee’s knees: local and landscape predictors of bee richness and abundance in backyard gardens. Urban Ecosyst. 17, 641 – 659. doi:, PMID: doi:10.1007/s11252-014-0349-0
  52. Pearl H., Ryan T., Howard M., Shimizu Y., Shapcott A. (2022). DNA barcoding to enhance conservation of sunshine coast heathlands. Diversity 14, 436. doi:, PMID: doi:10.3390/d14060436
  53. Phillips R. D., Hopper S. D., Dixon K. W. (2010). Pollination ecology and the possible impacts of environmental change in the Southwest Australian Biodiversity Hotspot. Philos. Trans. R. Soc. B 365, 517 – 528. doi:, PMID: doi:10.1098/rstb.2009.0238
  54. Quail M. A., Kozarewa I., Smith F., Scally A., Stephens P. J., Durbin R.. (2008). A large genome center’s improvements to the Illumina sequencing system. Nat. Methods 5, 1005. doi:, PMID: doi:10.1038/nmeth.1270
  55. Ramalho M. (2004). Stingless bees and mass flowering trees in the canopy of Atlantic Forest: a tight relationship. Acta Botanica Brasilica 18, 37 – 47. doi:, PMID: doi:10.1590/S0102-33062004000100005
  56. Robertson A. W., Ladley J. J., Kelly D. (2005). Effectiveness of short-tongued bees as pollinators of apparently ornithophilous New Zealand mistletoes. Austral Ecol. 30, 298 – 309. doi:, PMID: doi:10.1111/j.1442-9993.2005.01474.x
  57. Rollin O., Pérez-Méndez N., Bretagnolle V., Henry M. (2019). Preserving habitat quality at local and landscape scales increases wild bee diversity in intensive farming systems. Agriculture Ecosyst. Environ. 275, 73 – 80. doi:, PMID: doi:10.1016/j.agee.2019.01.012
  58. Russo L., Vaudo A. D., Fisher C. J., Grozinger C. M., Shea K. (2019). Bee community preference for an invasive thistle associated with higher pollen protein content. Oecologia 190, 901 – 912. doi:, PMID: doi:10.1007/s00442-019-04462-5
  59. Seitz N., vanEngelsdorp D., Leonhardt S. D. (2020). Are native and non-native pollinator friendly plants equally valuable for native wild bee communities ? Ecol. Evol. 10, 12838 – 12850. doi:, PMID: doi:10.1002/ece3.6826
  60. Sickel W., Ankenbrand M. J., Grimmer G., Holzschuh A., Härtel S., Lanzen J.. (2015). Increased efficiency in identifying mixed pollen samples by meta-barcoding with a dual-indexing approach. BMC Ecol. 15, 20. doi:, PMID: doi:10.1186/s12898-015-0051-y
  61. Sickel W., Kulow J., Krüger L., Dieker P. (2023). BEE-quest of the nest: A novel method for eDNA-based, nonlethal detection of cavity-nesting hymenopterans and other arthropods. Environ. DNA 5, 1163 – 1176. doi:, PMID: doi:10.1002/edn3.490
  62. Slattery P. S., Parslow B. A., Lee M. S., Batley M., Walker K. L., Schwarz M. P. (2023). Disparate continental scale patterns in floral host breadth of Australian colletid bees (Colletidae: Hymenoptera). Apidologie 54, 17. doi:, PMID: doi:10.1007/s13592-023-00996-z
  63. Sobek S., Tscharntke T., Scherber C., Schiele S., Steffan-Dewenter I. (2009). Canopy vs. understory: Does tree diversity affect bee and wasp communities and their natural enemies across forest strata ? For. Ecol. Manage. 258, 609 – 615. doi:, PMID: doi:10.1016/j.foreco.2009.04.026
  64. Somme L., Moquet L., Quinet M., Vanderplanck M., Michez D., Lognay G.. (2016). Food in a row: urban trees offer valuable floral resources to pollinating insects. Urban Ecosyst. 19, 1149 – 1161. doi:, PMID: doi:10.1007/s11252-016-0555-z
  65. Specht R. (1970). “ Vegetation,” in The Australian environment, 4 ed. Ed. Leeper G. (CSIRO Melbourne University Press, Melbourne), 44 – 67.
  66. Staab M., Pufal G., Tscharntke T., Klein A. M. (2018). Trap nests for bees and wasps to analyse trophic interactions in changing environments—A systematic overview and user guide. Methods Ecol. Evol. 9, 2226 – 2239. doi:, PMID: doi:10.1111/2041-210X.13070
  67. Steckel J., Westphal C., Peters M. K., Bellach M., Rothenwoehrer C., Erasmi S.. (2014). Landscape composition and configuration differently affect trap-nesting bees, wasps and their antagonists. Biol. Conserv. 172, 56 – 64. doi:, PMID: doi:10.1016/j.biocon.2014.02.015
  68. Stouffer D. B., Cirtwill A. R., Bascompte J. (2014). How exotic plants integrate into pollination networks. J. Ecol. 102, 1442 – 1450. doi:, PMID: doi:10.1111/1365-2745.12310
  69. Tonietto R. K., Larkin D. J. (2018). Habitat restoration benefits wild bees: A meta-analysis. J. Appl. Ecol. 55, 582 – 590. doi:, PMID: doi:10.1111/1365-2664.13012
  70. Ulyshen M. D., Soon V., Hanula J. L. (2010). On the vertical distribution of bees in a temperate deciduous forest. Insect Conserv. Diversity 3, 222 – 228. doi:, PMID: doi:10.1111/j.1752-4598.2010.00092.x
  71. Vanbergen A. J., Baude M., Biesmeijer J. C., Britton N. F., Brown M. J. F., Bryden J.. (2013). Threats to an ecosystem service: pressures on pollinators. Front. Ecol. Environ. 11, 251 – 259. doi: doi:10.1890/120126
  72. Vaudo A. D., Biddinger D. J., Sickel W., Keller A., López-Uribe M. M. (2020). Introduced bees (Osmia cornifrons) collect pollen from both coevolved and novel host-plant species within their family-level phylogenetic preferences. R. Soc. Open Sci. 7, 200225. doi:, PMID: doi:10.1098/rsos.200225
  73. Vila M., Bartomeus I., Dietzsch A. C., Petanidou T., Steffan-Dewenter I., Stout J. C.. (2009). Invasive plant integration into native plant–pollinator networks across Europe. Proc. R. Soc. B: Biol. Sci. 276, 3887 – 3893. doi:, PMID: doi:10.1098/rspb.2009.1076
  74. Voulgari-Kokota A., Ankenbrand M. J., Grimmer G., Steffan-Dewenter I., Keller A. (2019). Linking pollen foraging of megachilid bees to their nest bacterial microbiota. Ecol. Evol. 9, 10788 – 10800. doi:, PMID: doi:10.1002/ece3.5599
  75. Voulgari-Kokota A., Steffan-Dewenter I., Keller A. (2020). Susceptibility of red mason bee larvae to bacterial threats due to microbiome exchange with imported pollen provisions. Insects 11, 373. doi:, PMID: doi:10.3390/insects11060373
  76. White T. J., Bruns T., Lee S., Taylor J. (1990). “ Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics,” in PCR protocols: a guide to methods and applications. Eds. Innis M., Gelfand D., Sninsky J., White T. (Academic Press, New York), 315 – 322.
  77. Wille A. (1983). Biology of the stingless bees. Annu. Rev. Entomology 28, 41 – 64. doi:, PMID: doi:10.1146/annurev.en.28.010183.000353
  78. Williams N. M., Cariveau D., Winfree R., Kremen C. (2011). Bees in disturbed habitats use, but do not prefer, alien plants. Basic Appl. Ecol. 12, 332 – 341. doi:, PMID: doi:10.1016/j.baae.2010.11.008
  79. Wilson R. S., Keller A., Shapcott A., Leonhardt S. D., Sickel W., Hardwick J. L.. (2021). Many small rather than few large sources identified in long-term bee pollen diets in agroecosystems. Agriculture Ecosyst. Environ. 310, 107296. doi:, PMID: doi:10.1016/j.agee.2020.107296
  80. Wilson R. S., Leonhardt S. D., Burwell C. J., Fuller C., Smith T. J., Kaluza B. F.. (2020). Landscape simplification modifies trap-nesting bee and wasp communities in the subtropics. Insects 11, 853. doi:, PMID: doi:10.3390/insects11120853
  81. Winfree R. (2010). The conservation and restoration of wild bees. Ann. New York Acad. Sci. 1195, 169 – 197. doi:, PMID: doi:10.1111/j.1749-6632.2010.05449.x
  82. Winfree R., Aguilar R., Vázquez D. P., LeBuhn G., Aizen M. A. (2009). A meta-analysis of bees’ responses to anthropogenic disturbance. Ecology 90, 2068 – 2076. doi:, PMID: doi:10.1890/08-1245.1
  83. Wollenweber E., Wieland A., Haas K. (2000). Epicuticular waxes and flavonol aglycones of the European mistletoe, Viscum album L. Z. für Naturforschung C 55, 314 – 317. doi:, PMID: doi:10.1515/znc-2000-5-602
  84. Wood T., Holland J., Goulson D. (2016). Diet characterisation of solitary bees on farmland: dietary specialisation predicts rarity. Biodiversity Conserv. 25, 2655 – 2671. doi:, PMID: doi:10.1007/s10531-016-1191-x
  85. Wood T. J., Holland J. M., Goulson D. (2017). Providing foraging resources for solitary bees on farmland: current schemes for pollinators benefit a limited suite of species. J. Appl. Ecol. 54, 323 – 333. doi:, PMID: doi:10.1111/1365-2664.12718
  86. Yoshida S., Cui S., Ichihashi Y., Shirasu K. (2016). The haustorium, a specialized invasive organ in parasitic plants. Annu. Rev. Plant Biol. 67, 643 – 667. doi:, PMID: doi:10.1146/annurev-arplant-043015-111702

Citation

Wilson, R. S., et al. (2026). Tall trees and exotic herbs identified in pollen and nest materials of seven cavity-nesting solitary bee species in Australia. Frontiers in Bee Science, Volume 4. https://doi.org/
Received
Accepted
Published
Volume
4 - 2026

Copyright

Copyright © 2026 Wilson, Keller, Leonhardt, Smith, Burwell, Fuller, Shapcott, Kaluza and Wallace.

License: https://creativecommons.org/licenses/by/4.0/

*Correspondence: H. M. Wallace

Article metrics

Views
0
Downloads
0
Citations
0
Shares
0

Related articles

ReviewStatus of beekeeping in Pakistan: apicultural significance, industry challenges, and opportunities for integrated genetic and disease research programsAmir Said, Mah Noor Khan, Mohamed Alburaki, Shahid Karim, Abdul Majid KhanBrief Research ReportA laboratory amitraz resistance assay for Varroa destructor may not be a reliable predictor of field-level amitraz efficacyDevan Rawn, Kiley J. Epperson, James C. Fulton, Cameron J. JackCorrectionCorrection: Effects of nutritional supplementation on honey bee Apis mellifera L. brood development, colony population growth, and honey yield in central EthiopiaW. A. Hailemariam, Mbajiorgu C.A, Baitsholetsi Gloria Mokolopi