1 A global review of urban pollinators and implications for maintaining

2 pollination services in tropical cities 3

4 Authors: 5 Pietro K. Maruyama1,*, Jéssica Luiza S. Silva2, Ingrid N. Gomes3, Camila Bosenbecker4, 6 Oswaldo Cruz-Neto2, Willams Oliveira5, João Custódio Fernandes Cardoso4, Alyssa B. 7 Stewart6, Ariadna Valentina Lopes2 8 9 1. Departamento de Genética, Ecologia e Evolução - ICB, Universidade Federal de Minas 10 Gerais, Belo Horizonte-MG, Brazil 11 2. Departamento de Botânica, Universidade Federal de Pernambuco, Recife-PE, Brazil 12 3. Programa de Pós-Graduação em Ecologia, Conservação e Manejo da Vida Silvestre, 13 Universidade Federal de Minas Gerais, Belo Horizonte-MG, Brazil 14 4. Programa de Pós-Graduação em Ecologia e Conservação dos Recursos Naturais, 15 Universidade Federal de Uberlândia, Uberlândia-MG, Brazil 16 5. Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, 17 Recife-PE, Brazil 18 6. Department of Plant Science, Faculty of Science, Mahidol University, Bangkok 10400, 19 Thailand 20 *Correspondence: [email protected]

21

22

23 Manuscript submitted as a book chapter for:

24 Ecology of Tropical Cities: Natural and Social Sciences Applied to the

25 Conservation of Urban Biodiversity

26 Editors: Fabio Angeoletto, Piotr Tryjanowski & Mark Fellowes

27 Publisher: Springer Nature, 2022

28 29 Abstract: 30 Pollinators provide essential ecosystem services worldwide, but dependence on biotic 31 pollination is higher in the tropics, where urbanization is expected to impact biodiversity more 32 severely. Here, we present a global review on urban pollinator studies with emphasis on the 33 tropics. From the 308 published studies that included information on pollinator groups, only 34 ~25 % were conducted in tropical regions, while ~65 % were carried out in the non-tropical 35 northern hemisphere. This overall trend was similar for all the major insect pollinator groups, 36 but not for vertebrates, which were overall less studied in both tropical and non-tropical 37 regions. The effects of urbanization on tropical pollinators are diverse and complex and likely 38 depend on the extent and type of urbanization, as well as the pollinator taxa studied. For both 39 insect and vertebrate pollinators, the existing studies suggest that tropical cities can support 40 generalist species tolerant of human activity, but the lack of studies hampers other general 41 conclusions. The underrepresentation of pollinator studies in tropical cities undermines the 42 value of urban biodiversity conservation in the most biodiverse regions of the world and 43 highlights a missing opportunity. Since promoting urban biodiversity benefits both nature and 44 people, it could be especially relevant in the Global South, where economic and social 45 inequalities are severe and pollinator conservation may contribute to sustainability goals. In 46 this context, initiatives that foster more international collaborations and research in the tropics 47 are essential for a better understanding of the effects of urbanization and the value of pollinators 48 in urban areas. Such knowledge can provide the basis for better urban planning strategies that 49 contribute to the conservation of biodiversity and maintenance of pollination services in 50 tropical cities. 51 1. Introduction 52 Human population growth has been accompanied by increasing conversion of natural 53 areas to urban ones, i.e., urbanization, often in regions considered as biodiversity hotspots (Seto 54 et al. 2012). Although sometimes erroneously considered as “biological deserts” because of the 55 loss of natural habitats, cities also hold the potential to harbor considerable diversity when 56 biodiversity-friendly urban “green spaces” are available and promoted (Sandström et al. 2006; 57 Aronson et al. 2017). In addition, urban biodiversity brings additional benefits through its 58 social and educational value, as an appreciation and broader understanding of the natural world 59 may lead to public involvement in conservation (Miller and Hobbs 2002). At the same time, 60 cities have unique conditions and act as strong biological filters, influencing the species able 61 to thrive in such environment (Spotswood et al. 2021 and references therein). 62 Among the many animals that are found across the urban landscape, pollinators are 63 known to provide important ecosystem services through their interactions with flowering 64 plants, and the role of urban green areas in promoting the conservation of pollinators has 65 received much attention recently (Hall et al. 2017; Wenzel et al. 2020; Silva et al. 2021a). 66 Plant-pollinator interactions are one of the most important ecological interactions and 67 ecosystem services in the world, as an estimated 87.5 % of angiosperms rely on biotic 68 pollination (Ollerton et al. 2011). Thus, these interactions are directly related to the persistence 69 and maintenance of biodiversity for both plants and their associated animals, and food supply 70 worldwide (Potts et al. 2010; IPBES 2016; Ollerton et al. 2017; Silva et al. 2021b). 71 Nevertheless, it is still unknown in many regions of the world how urbanization threatens 72 pollination, and therefore ecological function and ecosystem services in urban areas. 73 Globally, estimates indicate that dependence on biotic pollination in natural areas is 74 higher in the tropics than in non-tropical regions (Ollerton et al. 2011; Rech et al. 2016). 75 Interactions between plants and pollinators in the tropics are also potentially more specialized, 76 considering the set of floral traits involved, than in non-tropical areas (Rosas-Guerrero et al. 77 2014). Moreover, some pollinator groups, such as vertebrates, are more diverse and relatively 78 more important for plant reproduction in the tropics (Fleming and Muchhala 2008; Ratto et al. 79 2018). Despite these differences, recent reviews of plant-pollinator interactions in urban areas 80 suggest that tropical studies are underrepresented in the international literature (Wenzel et al. 81 2020; Silva et al. 2021a). This reflects a general trend that, while the importance of urban 82 biodiversity is widely recognized (e.g., Aronson et al. 2017, Spostwood et al. 2021), the world’s 83 most biodiverse regions from the Global South are often understudied regarding urban 84 biodiversity (McDonald et al. 2020). Considering the paradox between the higher importance 85 of biotic pollination and the underrepresentation of urban pollinator studies in the tropics, in 86 this chapter we discuss known patterns about the global distribution of pollinators, with an 87 emphasis on urban areas, and compare tropical and non-tropical regions. Then, we review some 88 relevant studies conducted on tropical urban pollinators, highlighting their findings to foster 89 future studies. 90 91 2. Global distribution of urban pollinator groups 92 Biodiversity is unevenly distributed throughout the world, with tropical regions 93 harboring higher overall biodiversity (Gaston 2000). This pattern includes plants (Kreft and 94 Jetz 2007) and many of the animal taxa that act as pollinators (Ollerton 2017; Eggleton 2020). 95 However, when considering distinct taxa separately, global distribution patterns may differ 96 among groups. For instance, bees, the dominant group of pollinators worldwide (Ollerton 97 2017), have the highest diversity not close to the equator, but at more arid mid-latitude regions, 98 resulting in a bimodal pattern of species richness (Orr et al. 2021). Detailed assessments of 99 diversity patterns for other specific groups of pollinators are not readily available, with many 100 scattered sources for distinct groups (Ollerton 2017). Bird- and bat-pollinated plants typically 101 evolved from bee-pollinated ancestors (e.g., Tripp and Manos 2008), and may comprise a 102 substantial proportion of pollination modes in distinct tropical regions of the world (e.g., 103 Machado and Lopes 2004; Girão et al. 2007; Ballesteros-Mejia et al. 2016). Hence, when 104 comparing tropical and non-tropical urban pollinators, we may expect to find a higher 105 representation of non-insect groups in the tropics because the species richness of both 106 vertebrate-pollinated plants and vertebrate pollinators are higher there (Nascimento et al. 107 2020). 108 109 2.1. Overview of urban studies 110 To assess the global distribution of pollinator groups found in urban areas, we carried 111 out a literature search using the ISI Web of Science – Science Citation Index Expanded 112 platform (www.webofknowledge.com) (last accessed on June 29, 2020) with the following 113 search strings: ‘‘urban* and pollinat*’’ in the title, keywords and/or abstract (see also Silva et 114 al. 2021a). After searching and sorting the references, we kept papers with information on 115 pollinator distribution in urban areas. These references included studies on plant-pollinator 116 interactions as well as those dealing exclusively with pollinator/floral visitor lists and natural 117 history information of animals in urban areas if these were referred by authors or identified by 118 us as potential pollinators. Studies that did not include information on pollinator groups were 119 excluded. Then, for each study, we extracted: (1) the geographical coordinates of the cities 120 studied (using information provided or accessing the centroid of the city reported) and (2) the 121 group of pollinators investigated. We considered the functional group or groups of pollinators 122 investigated in each study for our overview and excluded animals that are not generally 123 considered pollinators, including true bugs (Hemiptera), dragonflies (Odonata), praying mantis 124 (Mantodea), stick-bugs (Phasmatodea), grasshoppers (Orthoptera), ants (Formicidae), and fruit 125 flies (Drosophilidae), even if reported on flowers. We categorized each study included after 126 screening as a tropical or non-tropical study. For simplicity, we considered ‘tropical’ areas to 127 be those located between the Tropic of Capricorn (23°26'13.4" S) and the Tropic of Cancer 128 (23°26'13.4" N). We used the coordinates of cities that were sampled (a study could have 129 several cities) to plot the studied cities on a map to assess the spatial trend of pollinator groups 130 studied in the literature, except for one study that sampled lepidopterans at 214 locations in the 131 United Kingdom (Bates et al. 2014) and another one that sampled one species of bee at 139 132 locations in Japan (Taki et al. 2017). In these cases, we took only the centroid of the respective 133 country for simplicity and to avoid overplotting. To assess the temporal trend of urban 134 pollinator studies, we generated a cumulative curve for all urban pollinator studies, with each 135 study being counted only once even if multiple cities were surveyed. No study sampled cities 136 in both tropical and non-tropical regions. We also created separate curves for each pollinator 137 group, except for mammals and “other insects” due to the small number of records. 138 Our survey returned a total of 752 studies which were first screened by their title and 139 abstract to check for suitability. This initial step eliminated 226 studies that did not deal with 140 pollinators or that were removed for other reasons (e.g., duplicates). The remaining 526 studies 141 were checked in detail, which led to the exclusion of an additional 218 studies that did not 142 include data on pollinator occurrence. Therefore, the analysis reported here refers to the 143 remaining 308 references published up to June 2020, which included data for the occurrence 144 and distribution of potential pollinator groups across the world (Fig. 1, Table S1). Potential 145 pollinators found across urban areas included insects: bees (Hymenoptera), wasps 146 (Hymenoptera), flies (Diptera), butterflies (Lepidoptera), moths (Lepidoptera), thrips 147 (Thysanoptera), beetles (Coleoptera); and vertebrates: hummingbirds (Trochilidae), passerine 148 birds (Passeriformes), parrots (Psittaciformes); bats (Chiroptera) and a squirrel (Sciuridae). 149 From the total of 308 studies, only 25.0 % (77 studies) are from the tropics (Fig. 2A). Of the 150 231 non-tropical studies, most were conducted in the northern hemisphere (199 studies; 86.1 151 % of non-tropical studies, and 64.6 % of all studies). Four regions of the world have been 152 especially well studied, leading to an agglomeration of points, so these areas have been 153 enlarged in the map to aid visualization (Fig. 1). Three of these highly studied regions are non- 154 tropical: Western USA, Eastern USA and Europe had 7.4 %, 12.2 % and 39.4 % of all pollinator 155 records in published studies, respectively. The only tropical representative, the southeastern 156 Brazil region, had 10.3 % of records. 157

158 159 160 Figure 1. Results from our literature survey on studies containing information about pollinator 161 groups reported in urban environments of the world. Dashed lines divide tropical and non- 162 tropical regions and distinct colors refer to the different pollinator groups. The regions with the 163 highest agglomeration of points (i.e., the most published studies) are enlarged below the world 164 map. Jittering was used on these insets to reduce overlap and improve visualization. The map 165 is presented using the Equal Earth map projection. “Other insects” are not shown due to the 166 small number of records for this group. 167 168 From the final 308 studies included in our analyses, we found a total of 438 records of 169 pollinator groups across urban areas (a study was counted more than once if it reported more 170 than one pollinator group; Fig. 1). The most common group found in the studies was 171 Hymenoptera (267 studies; 61.0 % of records), followed by Diptera (57; 13.0 %), Lepidoptera 172 (56; 12.8 %), Coleoptera (25; 5.7 %), birds (24; 5.5 %), mammals (6; 1.4 %), and “other 173 insects” (3; 0.7 %). In general, fewer pollinator records were found in tropical regions. Among 174 studies with Hymenoptera, only 57 records (21.3 %) were from the tropics, while 210 were 175 from non-tropical regions (Fig. 2D). Similarly, 12.3 % of records for Diptera were from the 176 tropics (7 tropical vs. 50 non-tropical; Fig. 2C), 19.6 % for Lepidoptera (11 vs. 45; Fig. 2E), 177 and 20.0 % for Coleoptera (5 vs. 20; Fig. 2B). All records for the “other insects” category were 178 from non-tropical regions, with one record for Thysanoptera and two for Neuroptera, although 179 in these cases it is still uncertain whether they were effective pollinators. Birds were the only 180 group with a similar number of studies in tropical and non-tropical regions, with 14 (58.3 %) 181 and 10 (41.7 %) records, respectively (Fig. 2F). Because specialized nectarivorous birds are 182 absent from well-studied Europe (Kissling et al. 2012), theoretically many more studies on 183 birds from tropical regions should have been found. Reports of mammals were scarce for both 184 regions, with only two non-tropical and four tropical studies. 185 When analyzing the temporal pattern of studies, we found that research in non-tropical 186 cities started much earlier (1997) than in their tropical counterparts (2006). Furthermore, over 187 the past decade, especially after 2013, there has been a boom of urban pollinator studies in both 188 regions, albeit less so in the tropics. In fact, 80.5 % (248) of studies were conducted from 2013 189 onwards, with 63 studies in tropical regions and 185 in non-tropical regions of the world (Fig 190 2). 191

192 193 194 Figure 2. Number of studies reporting pollinator groups in urban areas over time, comparing 195 tropical (solid lines) and non-tropical (dotted lines) regions. (A) Total cumulative number of 196 studies and (B - F) the cumulative number for each pollinator group reported in these studies. 197 B - F are adjusted to the same scale to facilitate comparison. Statistical values within each 198 frame show the results of goodness of fit chi-squared tests evaluating the difference between 199 tropical and non-tropical records. Mammals and “other insects” are not shown due to the small 200 number of records for these groups. 201 202 2.2. Pollinator groups in tropical urban landscapes 203 2.2.1. Insects (Bees) 204 Insects are responsible for the pollination of most plant species, and bees in particular 205 are the dominant pollinators in both non-tropical and tropical environments, contributing to the 206 conservation and maintenance of natural ecosystems and providing ecosystem services 207 (Michener 2007; Potts et al. 2010; IPBES 2016, Montoya‐Pfeiffer et al. 2020). The dependence 208 of bees on floral resources throughout their life cycle is related to the importance of this group 209 in the pollination of several angiosperm species, as bees require resources other than nectar to 210 feed their offspring and maintain their nests, such as pollen, oil, and resin (Aleixo et al. 2014; 211 Ollerton 2017; Rocha-Filho et al. 2018). Furthermore, bees are also reported to be the most 212 effective pollinators of several crops (Giannini et al. 2015; IPBES 2016). Despite their 213 importance, bee diversity has been decreasing (Potts et al. 2010). One of the main factors 214 responsible for this decline is land use modification, including urbanization (Harrison et al. 215 2017; Millard et al. 2021; Zattara and Aizen 2021). However, some characteristics of the urban 216 environment and the biology of bees allow some species to thrive in cities (Hennig and Ghazoul 217 2011; Hall et al. 2017). Characteristics of the urban environment beneficial to bees include a 218 supply of flowers throughout the year in gardens and other green areas, as well as structures 219 that can be used by bees to build their nests, such as pre-existing cavities in walls, buildings 220 and wood structures (Osborne et al. 2008; Baldock et al. 2019; Turo and Gardiner 2019). This 221 change in perspective about urban areas as habitats for bee conservation and other insect 222 pollinators has gained momentum recently (Hall et al. 2017; Baldock et al. 2019). However, 223 knowledge about tropical urban bees remains scarce, since most studies evaluating the impact 224 of urbanization on bees have been carried out in temperate cities (Banaszak-Cibicka and 225 Żmihorski 2012; Buchholz and Egerer 2020; Nascimento et al. 2020; Fig. 2D). 226 Some recent studies on tropical urban environments, nevertheless, reinforce the 227 importance of bees as pollinators. In Bangkok, Thailand, bees represent the majority of 228 pollinator species found across urban green areas (Stewart et al. 2018; Stewart and 229 Waitayachart 2020), with stingless bees comprising 64.32 % of the pollinators recorded 230 (Stewart et al. 2018). Such a high proportion of stingless bees was also found in the city of 231 Belo Horizonte, Brazil (Zanette et al. 2005). It is worth noting that, of more than 330 potential 232 pollinator species found across urban areas in Brazil, stingless bees were associated with the 233 highest number of plant species, second only to the invasive honeybee, Apis mellifera 234 (Nascimento et al. 2020). Another study carried out in Brazil demonstrated the importance of 235 the urban environment in providing resources to small populations of the oil collecting bee 236 Centris (Melacentris) collaris (Rocha-Filho et al. 2018), indicating that some specialized floral 237 resources may be found in urban environments and are essential for the maintenance of 238 specialized bees. High floral abundance and diversity are the most important variables related 239 to the maintenance of bees from different groups, offsetting the negative effects commonly 240 associated with urbanization (Frankie et al. 2013; Hülsmann et al. 2015; Ayers and Rehan 241 2021). Such positive effects of floral resource availability have been described for cities in 242 tropical countries such as Thailand (Tangtorwongsakul et al. 2018; Stewart and Waitayachart 243 2020) and Costa Rica (Wojcik and McBride 2012), and is consistent with studies carried out 244 in non-tropical regions (e.g., Ahrné et al. 2009; Matteson and Langellotto 2010; Bates et al. 245 2011; Hennig and Ghazoul 2011; Pardee and Philpott 2014; Hülsmann et al. 2015). 246 When evaluating the effects of the surrounding urban matrix on the persistence of 247 different groups of bees in urban green areas, results are varied. Cândido et al. (2018), for 248 instance, reported a decrease in the richness and abundance of orchid bees (Apidae: Euglossini) 249 found in forest fragments as developed area and proximity to the urban center increased in the 250 southeastern Amazon. For stingless bees, urban coverage had negative effects on abundance 251 and richness in southern Thailand (Wayo et al. 2020) and southeastern Brazil (Zanette et al. 252 2005). A temporal assessment of increasing urbanization over 30 years in Liberia, Costa Rica, 253 showed a decline in the abundance and diversity of bees visiting Andira inermis (Fabaceae) 254 (Frankie et al. 2009). In contrast, other authors report neutral or even positive effects of the 255 surrounding urban matrix on bees in the tropics. Sampling stingless bees in urban vegetation 256 remnants of Belo Horizonte, Brazil, Antonini et al. (2013) found no significant relationship 257 between the degree of urbanization and the diversity of stingless bees. In Bangkok, Thailand, 258 urban coverage was positively associated with bee richness (Tangtorwongsakul et al. 2018). 259 Finally, Guenat et al. (2019) showed that overall bee abundances were not affected by 260 urbanization in tropical Ghana. Such differences may reflect bee biology, but may also stem 261 from differences in the types of urban green spaces sampled (such as fragments of urban forest, 262 orchards, public squares and streets), as well as the different methodologies used to assess bee 263 abundance and diversity. In fact, two studies conducted in the same city (Belo Horizonte, 264 Brazil) report contrasting effects of urbanization (negative in Zannete et al. 2005 and neutral 265 in Antonini et al. 2013). However, they were carried out in different types of urban green 266 spaces, encompassing distinct habitats in the former and only vegetation remnants in the latter. 267 These discrepancies suggest the importance of further studies in tropical cities, using more 268 standardized methodologies and including current approaches such as the assessment of bee 269 functional traits to evaluate the responses of different groups of bees to urbanization (e.g., 270 Guenat et al. 2019). Moreover, most studies on “urban bees” in the tropics seem not to be 271 carried out in heavily modified urban habitats, but on natural vegetation remnants or orchards 272 surrounded by the urban matrix (e.g., Antonini et al. 2013; Cândido et al. 2018; 273 Tangtorwongsakul et al. 2018; Wayo et al. 2020), in contrast to how studies are often conducted 274 in temperate areas. Furthermore, many studies are faunal surveys of urban green areas (e.g., 275 Nemésio and Silveira 2007; Gazola and Garófalo 2009; Nemésio and Silveira 2010; Aidar et 276 al. 2013; Viotti et al. 2013; Oliveira et al. 2015; Possamai et al. 2017), not specifically assessing 277 the effect of urbanization-related variables on bee communities. Therefore, more research 278 specifically evaluating local and landscape characteristics needs to be conducted in tropical 279 cities to understand the impacts of urbanization and to enhance the conservation value of cities 280 for bees and other pollinators (Hernandez et al. 2009). 281 Finally, t should also be noted that while bees are the most important pollinators, other 282 relevant insect pollinators are rarely studied specifically, mostly appearing in studies that 283 investigated insects in general, together and in complementation with bees (e.g., Stewart et al. 284 2018; Guenat et al. 2019). This finding does not seem to be a shortcoming only for tropical 285 studies, and considering the importance of distinct insect groups as pollinators for a variety of 286 plants (Ollerton 2017; Doyle et al. 2020; Brock et al. 2021), more studies focusing specifically 287 on these neglected groups would be welcome. 288 289 2.2.2. Birds, bats, and other vertebrates 290 Vertebrate pollination, especially involving birds and bats, is more common in the 291 tropical and subtropical regions of the world, comprising distinct and independent evolutionary 292 radiations in the New and Old Worlds (Fleming and Muchhala 2008; Fleming et al. 2009). 293 Furthermore, floral interactions for both birds and bats seem to be more specialized in the 294 Neotropics than in the Paleotropics (Fleming and Muchhala 2008; Zanata et al. 2017). Studies 295 of bird and bat pollination in tropical urban areas are not very common, but there are some 296 examples (Fig. 1; Fig. 2F). Within birds, more than 920 species pollinate plants from 297 approximately 65 families (Cronk and Ojeda 2008; Whelan et al. 2015), but three families are 298 considered specialized nectarivores and are usually associated mutualistically with plants: 299 hummingbirds - Trochilidae, sunbirds - Nectariniidae, and honeyeaters - Meliphagidae (Cronk 300 and Ojeda 2008). Birds, including those acting as pollinators, are sensitive to and respond 301 quickly to environmental changes (Whelan et al. 2008). Even though many avian pollinators 302 manage to persist in urban areas, they are especially influenced by the availability of nectar in 303 these environments (Davis et al. 2015). For instance, the supply of artificial feeders in urban 304 and peri-urban environments can increase the occurrence of hummingbird sightings (Meehan 305 et al. 2020), reduce visitation rates and seed-set of native plant species associated with 306 hummingbirds and sunbirds (Arizmendi et al. 2007; du Plessis et al. in press) and change the 307 migratory behavior of hummingbirds due to the surplus of resources (Greig et al. 2017). In this 308 context, urbanization may decrease the diversity of nectarivorous birds, especially affecting the 309 more specialized species, as was shown for sunbirds in South Africa (Pauw and Louw 2012). 310 In the tropics, the same seems to happen with hummingbirds (Maruyama et al. 2019). 311 Nectarivores with more generalized morphology are apparently better adapted to 312 anthropization, while specialists are more sensitive to environmental changes (Coetzee et al. 313 2018; Maruyama et al. 2019). In this sense, urban environments act as an ecological filter that 314 favors generalist species from the regional pool and changes the structure of the community of 315 nectarivorous birds (Puga-Caballero et al. 2020). Nevertheless, only a few studies have 316 evaluated pollination by birds in urban environments in the tropics. In Brazil, an urban forest 317 remnant was found to harbor a high diversity of hummingbirds, emphasizing the importance 318 of such habitats for them; the hummingbirds also used such areas as a refuge, feeding in the 319 nearby urbanized area during periods of floral resource scarcity (Rodrigues and Araujo 2011). 320 However, the value of vegetated area is site-specific and species-specific, as another study from 321 Brazil found an urban vegetation remnant to be unattractive to the most specialized 322 hummingbird species in the region (Matias et al. 2016). Thus, urbanization leads to more 323 generalized plant-hummingbird interaction networks due to the absence of functionally 324 specialized species (Maruyama et al. 2019). In Singapore, the fruit-set of the mangrove tree 325 Bruguiera gymnorrhiza (Rhizophoraceae) was negatively affected by the cascading effects of 326 fragment size and reduced visitation of pollinating sunbirds in urban mangroves (Wee et al. 327 2015). Thus, urbanization leads to the loss or reduced availability of some avian pollinators, 328 increased pollen limitation, altered foraging behavior, and, consequently, reduced plant fertility 329 in tropical bird pollinated plants. Birds were the only group of pollinators in which we did not 330 see an imbalance in the number of studies between tropical and non-tropical regions (Fig. 2F). 331 This finding is likely explained by the fact that specialized nectarivorous birds are absent from 332 many non-tropical areas such as Europe (Kissling et al. 2012), and that some tropical urban 333 areas, as in southeastern Brazil (Fig. 1), has been relatively well studied, balancing out the non- 334 tropical bias in urban pollinator studies. 335 Within mammals, bats are important pollinators associated with more than 528 species 336 of angiosperms, distributed in 67 families worldwide (Fleming et al. 2009). Pollinating bats are 337 represented mainly by two families, Pteropodidae in the Old World and Phyllostomidae in the 338 New World (Kunz et al. 2011). Bat pollination involves highly rewarding nocturnal flowers 339 visited by animals that show long-distance flying capacity, hence potentially promoting long- 340 distance pollen dispersal (Fleming et al. 2009; Muchhala and Thomson 2010). Specific studies 341 of bat pollination in urban areas are not common (Fig. 1), but a recent study in Brazil found 342 that a specialized bat-pollinated plant mostly experienced short distance and within-individual 343 pollen exchange in the urban environment, suggesting that outcrossing is diminished between 344 isolated plants in the urban area (Diniz et al. 2019). In Thailand, Sritongchuay et al. (2019) 345 found that the specialization of bat-flower interaction networks in fruit orchards was negatively 346 affected by urbanization at the landscape level during the period of lower floral resource 347 availability. This effect was seemingly driven by the higher generalization of frugivorous bat 348 species that occasionally complement their diet with nectar, while the exclusively 349 nectarivorous bat species show a constant degree of flower use across different levels of 350 urbanization (Sritongchuay et al. 2019). New and Old World nectar-feeding bats represent 351 distinct evolutionary pathways that converged in terms of many aspects of their interactions 352 with flowers (Fleming and Muchhala 2008; Fleming et al. 2009) and the few available studies 353 from both realms show that bat pollination is affected by urbanization (decreased specialization 354 and pollen dispersal). However, the lack of more studies clearly impairs any generalizations on 355 how urbanization affects bat pollination, and relevant factors may include roost availability, 356 and light pollution among others (Diniz et al. 2019; Sritongchuay et al. 2019). Roosting site 357 availability may be especially relevant, as a study from Peninsular Malaysia found a diverse 358 number of plant species associated with the cave nectar bat, Eonycteris spelaea (Pteropodidae), 359 inhabiting an urban cave (Lim et al. 2018). Another limiting factor may be the lack of night- 360 blooming plant species in cities since urban landscaping tends to favor showy day-blooming 361 species (Loram et al. 2008). Information about other non-flying mammal pollinators in urban 362 areas is even rarer than for bats, but a study from subtropical Taiwan recorded pollination by 363 Red-bellied squirrels (Callosciurus erythraeus, Sciuridae) in Mucuna macrocarpa (Fabaceae) 364 in an urban area (Kobayashi et al. 2018). This suggests that even these rare pollinators may be 365 conserved in the urban landscape if appropriate conditions are met. 366 367 2.2.3. Community studies including multiple pollinator groups 368 Going beyond group-specific studies, there are a handful of studies that analyzed 369 broader pollinator communities and interactions with flowers across the tropical urban 370 landscape. One study in Bangkok, Thailand recorded visitation of different pollinator groups 371 visiting flowers (which were mostly insects, especially bees) across different urban green 372 spaces (Stewart et al. 2018). They found that pollinator richness and abundance were positively 373 associated with the size of the urban green space and floral abundance, but negatively affected 374 by the percentage of vegetated area surrounding the sampled sites. The negative effect of 375 surrounding vegetation is potentially related to the fact that such vegetation mostly consisted 376 of intensively-managed lawns and hedges, which are likely unattractive to pollinators (Stewart 377 et al. 2018), suggesting that not all urban green spaces promote pollinators. Adding to this 378 complexity in the response of pollinator communities, Guenat et al. (2019) found that distinct 379 insect groups that potentially act as pollinators responded differently to urbanization in Ghana, 380 Africa (Guenat et al. 2019). Moreover, for bees, they also recorded that urbanization favored 381 short-tongued and ground-nesting species over long-tongued and cavity-nesting species, thus 382 indicating that not all of the potential functional diversity of bee pollinators was maintained 383 (Guenat et al. 2019). In Brazil, a country-wide review of pollinator-plant interactions across 384 the urban landscape found that distinct pollinator groups, i.e., insects and vertebrates, form 385 loosely-connected interaction modules (Nascimento et al. 2020), suggesting that distinct 386 pollinator groups use urban floral resources differently across the urban area. The 387 comparatively fewer number of studies in tropical areas makes generalization and comparison 388 with non-tropical areas difficult, but the few studies conducted indicate the importance of 389 considering different pollinator groups simultaneously, and of better characterizing urban green 390 spaces to achieve a more comprehensive and inclusive approach for urban pollinator 391 conservation in the tropics. 392 393 3. Ecosystem services provided by pollinators in the urban setting 394 Recent studies reveal that pollination by animal vectors is frequent in urban green areas 395 (Oliveira et al. 2019, 2020; Silva et al. 2020; Theodorou et al. 2020; Wenzel et al. 2020; Silva 396 et al. 2021a). In urban green spaces, a diversity of pollinator species may contribute strongly 397 to the maintenance of plant populations, including native, exotic and invasive species (e.g., 398 Lowenstein et al. 2015; Oliveira et al. 2019). Nevertheless, most knowledge about pollination 399 services in urban ecosystems is concentrated in temperate regions and developed nations (e.g., 400 Baldock et al. 2020; Theodorou et al. 2020; Wenzel et al. 2020), with few examples assessing 401 the effects of urbanization on plant reproduction in tropical regions (e.g., Wee et al. 2015, 402 Oliveira et al. 2019, 2020). 403 As an ecosystem service, biotic pollination is associated with the agricultural 404 production of about 35 % of world crops (Klein et al. 2007; IPBES 2016). It is estimated that 405 87 out of the 115 major crops grown worldwide depend on biotic pollination to set fruits and 406 seeds, to at least some degree (Klein et al. 2007). In terms of crops that are dependent on biotic 407 pollination, such as coffee, apple, tomato, blueberry and cocoa, the annual yield is 1.23x109 408 tonnes in non-tropical regions, and 3.52x109 tonnes in the tropics (Porto et al. 2020). The 409 estimated value of this pollination service worldwide ranges from US$195 billion to ~US$387 410 billion annually (reviewed and adjusted according to inflation in Porto et al. 2020, see the 411 article for details). Urban areas can also contribute to food production (Nichols et al. 2020), 412 and projections of ecosystems services provided by urban vegetation and associated with urban 413 agriculture estimate that as much as US$80–160 billion annually worldwide could be generated 414 in scenarios of intense urban agriculture (Clinton et al. 2018). Many crops in urban landscapes 415 require biotic pollination, including in tropical regions (Guenat et al. 2019). Urban agriculture 416 has grown considerably and gained attention around the world, especially considering food 417 security (Orsini et al. 2013; Ackerman et al. 2014; Nichols et al. 2020). This practice may be 418 especially relevant for low-income populations in both developed and developing economies 419 (Van Veenhuizen 2006; De Zeeuw et al. 2011; Orsini et al. 2013; Nichols et al. 2020), and 420 includes the cultivation of fruit trees (e.g., Citrus sinenis, Carica papaya, Lycopersicon 421 esculentum, genus Fragaria); medicinal (e.g., Hibiscus esculentus), aromatic (e.g., Hibiscus 422 sabdariffa, Ocimum basilicum) and ornamental plants (e.g., genus Bougainvillea); and plants 423 that favor beekeeping, among others (Orsini et al 2013). In addition, this type of agriculture 424 has been practiced in diverse types of urban green spaces, such as green roofs, gardens, and 425 vacant lots. These studies have shown that the pollination services provided by bees in urban 426 agriculture in residential gardens can be independent of the landscape context (e.g., Smith et 427 al. 2006; Frankie et al. 2009; Potter and Lebuhn 2015; Bennett and Lovell 2019; Zhao et al. 428 2019). 429 Overall, since urbanization often exerts more negative than positive effects on plant- 430 pollinator interactions by reducing the diversity and frequency of flower visitors both in the 431 tropics and in non-tropical regions (Geslin et al. 2013; Matteson et al. 2013; Maruyama et al. 432 2019; Oliveira et al. 2019, 2020; Silva et al. 2021a), delivery of pollination services in urban 433 areas may be relatively low. Some studies have indicated that cascading effects of urbanization 434 on plant-pollinator interactions result in reduced female reproductive success for native plants, 435 i.e., fruit- and seed-set, in both tropical and non-tropical regions (Pellissier et al. 2012; Oliveira 436 et al. 2019). Negative impacts on native plant reproduction may be even greater when 437 pollinators are attracted to the exotic plant species that are frequently cultivated in urban areas, 438 rather than to native plants (Matteson and Langellotto 2011; Helden et al. 2012; Stewart et al. 439 2018, but see Nascimento et al. 2020). For crop plants used in urban agriculture, quantitative 440 assessment is rare, but experimental studies in temperate regions show that, at the garden scale, 441 a higher diversity of bees led to higher pollination success for cucumbers and eggplants in 442 Chicago (Lowenstein et al. 2015), and jalapeño peppers in California, USA (Cohen et al. 2021). 443 However, the latter study also showed that seed-set decreased with the increase in the 444 proportion of semi-natural habitats in the landscape, indicating the complex role of surrounding 445 vegetation and the importance of local-scale factors in the conservation of ecosystem services 446 (Cohen et al. 2021). Similar experimental studies for tropical urban areas, however, are still 447 lacking. 448 449 4. Concluding remarks and future perspectives 450 Urbanization is occurring rapidly worldwide and may especially impact biodiversity 451 hotspots (Seto et al. 2013). Moreover, land-use change is one of the main human-induced 452 environmental impacts recognized as a driver of pollinator declines (Potts et al. 2016; Millard 453 et al. 2021). Such declines are troubling given that pollination is a highly valuable ecosystem 454 service that contributes to the sustainable development of cities, and yet it is susceptible to the 455 negative effects of urbanization (Geslin et al. 2013; Harrison and Winfree 2015; Baldock 2020; 456 Nicholls et al. 2020; Wenzel et al. 2020; Silva et al. 2021a). Studies in urban areas generally 457 indicate that urbanization does indeed lead to reductions in pollinator diversity, for both insects 458 and vertebrates, but the response of pollinators to urbanization is complex and dependent on 459 the group and the context investigated (e.g., Guenat et al. 2019; Stewart et al. 2018; Diniz et 460 al. 2019; Maruyama et al. 2019; Oliveira et al. 2019). Despite the importance of pollinators, 461 particularly in tropical areas, only a few comprehensive studies are available from the tropics 462 (e.g., Nascimento et al. 2020). The objective of this review was therefore to compile what is 463 known about the effects of urbanization on pollinators in tropical areas, and point future venues 464 of research. 465 One of the most striking findings of this review is that there are three times more studies 466 examining the effect of urbanization on pollinators in non-tropical areas (232 studies) than in 467 the tropical ones (77 studies), and more studies in the New World tropics than the Old World 468 tropics (Fig. 1). Moreover, we found that, while the number of studies examining the effect of 469 urbanization on pollinators has grown exponentially over the past several years, the number of 470 studies is increasing at a much faster pace in non-tropical areas than in tropical areas (Fig. 2). 471 The disparity between regions is even greater when considering that overall plant and pollinator 472 diversity is higher in tropical areas (Gaston 2000 and references therein), yet the number of 473 studies in tropical areas is substantially lower. These findings highlight the need for additional 474 research in tropical urban areas, particularly since most of the world’s future population growth 475 will occur in the tropics (Seto et al. 2012). 476 This review also reveals that the effects of urbanization on tropical pollinators are 477 diverse, and they likely depend on the extent and type of urbanization, as well as the pollinator 478 taxa studied. We have the most data on bees, and studies have revealed surprisingly high bee 479 diversity and abundance in urban areas, which most studies (both non-tropical and tropical) 480 attribute to the abundance of floral resources found in cities (Ahrné et al. 2009; Matteson and 481 Langellotto 2010; Bates et al. 2011; Hennig and Ghazoul 2011; Wojcik and McBride 2012; 482 Pardee and Philpott 2014; Hülsmann et al. 2015; Stewart et al. 2018; Tangtorwongsakul et al. 483 2018; Stewart and Waitayachart 2020). However, it also appears that most of the bee diversity 484 in cities is due to generalist bee species that have flexible diets and nesting habits, which 485 stresses the importance of maintaining natural habitats for rare and specialist species. While 486 we have less data on the effects of urbanization on vertebrate pollinators, the few studies that 487 exist also suggest that cities can support generalist species that are tolerant of human 488 development and activity, if their dietary and nesting or roosting requirements are met (Pauw 489 and Louw 2012; Lim et al. 2018, Diniz et al. 2019; Maruyama et al. 2019). 490 The underrepresentation of pollinator studies in tropical cities hampers general 491 conclusions and frameworks for urban pollinator diversity and undermines the value of urban 492 biodiversity conservation in the most biodiverse regions of the world (McDonald et al. 2020). 493 We argue that the imbalance between regions highlights a missing opportunity, as recognizing 494 and promoting urban biodiversity benefits both nature and people (Dearborn and Kark 2010). 495 Promoting urban biodiversity may be particularly beneficial in the Global South where 496 economic and social inequalities are especially severe, and pollinator conservation may 497 contribute to sustainability goals (Dobbs et al. 2019; Nichols et al. 2020). Therefore, initiatives 498 that foster more international collaborations and research in these regions are essential for a 499 better understanding of the effects of urbanization and the value of pollinators in urban areas. 500 Such data can provide the basis for better urban planning strategies that contribute to the 501 conservation of biodiversity and maintenance of pollination services in tropical cities. 502 503 Acknowledgments 504 We thank Rogério V. Gonçalves for his patience and essential help with the map figure. PKM 505 acknowledge the support by PRPQ-UFMG (Call #09/2019) and FAPEMIG (Grant RED- 506 00253-16); ING was supported by CAPES (Finance code 001) and Brazilian Biodiversity 507 Fund/Humanize Institute (FUNBIO grant 0042021); CB was supported by CNPq (proc. 508 160722/2020-9). 509

510 References

511 Ackerman, K., Conard, M., Culligan, P., Pluntz, R., Sutto, M.P., and Whittinghill, L. 2014. 512 Sustainable food systems for cities: the potential of urban agriculture. The Economic and Social 513 Review 45:189-206.

514 Aidar, I.F., Santos, A.O.R., Bartelli,, B.F., Martins, G.A., and Nogueira-Ferreira, F.H. 2013. 515 Nesting ecology of stingless bees (Hymenoptera, Meliponina) in urban areas: the importance 516 of afforestation. Bioscience journal 29: 1361-1369.

517 Ahrne, K., Bengtsson, J., and Elmqvist, T. 2009. Bumble bees (Bombus spp) along a gradient 518 of increasing urbanization. PloS one 4:e5574. https://doi.org/10.1371/journal.pone.0005574.

519 Aleixo, K.P., de Faria, L.B., Groppo, M., Castro, M.M.N., and da Silva, C.I. 2014. 520 Spatiotemporal distribution of floral resources in a Brazilian city: Implications for the 521 maintenance of pollinators, especially bees. Urban Forestry & Urban Greening 13:689–696. 522 http://dx.doi.org/doi:10.1016/j.ufug.2014.08.002.

523 Antonini, Y., Martins, R.P., Aguiar, L.M., and Loyola, R.D. 2013. Richness, composition and 524 trophic niche of stingless bee assemblages in urban forest remnants. Urban Ecosystems 16: 525 527–541. https://doi.org/10.1007/s11252-012-0281-0.

526 Arizmendi, M.C., Monterrubio-Solís, C., Juárez, L., Flores-Moreno, I., and López-Saut, E. 527 2007. Effect of presence of nectar feeders on the breeding success of Salvia mexicana and 528 Salvia fulgens in a suburban park near México City. Biological Conservation 136:155-158. 529 https://doi.org/10.1016/j.biocon.2006.11.016.

530 Aronson, M.F., Lepczyk, C.A., Evans, K.L., Goddard, M.A., Lerman, S.B., MacIvor, J.S., 531 Nilon, C.H., and Vargo, T. 2017. Biodiversity in the city: key challenges for urban green space 532 management. Frontiers in Ecology and the Environment 15:189-196. 533 https://doi.org/10.1002/fee.1480.

534 Ayers, A.C., and Rehan, S.M. 2021. Supporting Bees in Cities: How Bees Are Influenced by 535 Local and Landscape Features. Insects 12:128. https://doi.org/10.3390/ insects12020128.

536 Baldock, K.C.R., Goddard, M.A., Hicks, D.M., Kunin, W.E., Mitschunas, N., Morse, H., 537 Osgathorpe, L.M., Potts, S.G., Robertson, K.M., Scott, A.V., Staniczenko, P.P.A., Stone, G.N., 538 Vaughan, I.P., and Memmott, J. 2019. A systems approach reveals urban pollinator hotspots 539 and conservation opportunities. Nature Ecology & Evolution 3:363–373. 540 https://doi.org/10.1038/s41559-018-0769-y. 541 Baldock, K.C.R. 2020. Opportunities and threats for pollinators conservation in global towns 542 and cities. Current Opinion in Insect Science 38:63-71. 543 https://doi.org/10.1016/j.cois.2020.01.006.

544 Ballesteros-Mejia, L., Lima, N.E., Lima-Ribeiro, M.S., and Collevati, R.G. 2016. Pollination 545 mode and mating system explain patterns in genetic differentiation in Neotropical plans. PLoS 546 ONE 11:e0158660. http://doi.org/10.1371/journal.pone.0158660.

547 Banaszak-Cibicka, W., and Żmihorski, M. 2012. Wild bees along an urban gradient: winners 548 and losers. Journal of Insect Conservation 16:331–343. https://doi.org/10.1007/s10841-011- 549 9419-2.

550 Bates, A.J., Sadler, J.P., Fairbrass, A.J., Falk, S J., Hale, J.D., and Matthews, T.J. 2011. 551 Changing bee and hoverfly pollinator assemblages along an urban-rural gradient. PloS one 552 6:e23459. https://doi.org/10.1371/journal.pone.0023459.

553 Bates, A.J., Sadler, J.P., Grundy, D., Lowe, N., Davis, G., Baker, D., Bridge, M., Freestone, 554 R., Gardner, D., Gibson, C., Hemming, R., Howarth, S., Orridge, S., Shaw, M., Tams, T., and 555 Young, H. 2014. Garden and landscape-scale correlates of moths of differing conservation 556 status: significant effects of urbanization and habitat diversity. PLoS One 9:e86925. 557 https://doi.org/10.1371/journal.pone.0086925.

558 Bennett, A.B., and Lovell, S. 2019. Landscape and local site variables differentially influence 559 pollinators and pollination services in urban agricultural sites. PLoS One 14:e0212034. 560 https://doi.org/10.1371/journal.pone.0212034.

561 Brock, R.E., Cini, A., and Sumner, S. 2021. Ecosystem services provided by aculeate wasps. 562 Online Biological Reviews. https://doi.org/10.1111/brv.12719.

563 Buchholz, S., and Egerer, M. H. 2020. Functional ecology of wild bees in cities: towards a 564 better understanding of trait-urbanization relationships. Biodiversity and Conservation 565 29:2779–2801. https://doi.org/10.1007/s10531-020-02003-8.

566 Cândido, M.E.M.B., Morato, E.F., Storck-Tonon, D., Miranda, P.N., and Vieira, L.J.S. 2018. 567 Effects of fragments and landscape characteristics on the orchid bee richness (Apidae: 568 Euglossini) in an urban matrix, southwestern Amazonia. Journal of Insect Conservation 569 22:475–486. https://doi.org/10.1007/s10841-018-0075-7.

570 Clinton, N., Stuhlmacher, M., Miles, A., Uludere Aragon, N., Wagner, M., Georgescu, M., 571 Herwig, C., and Gong, P. 2018. A global geospatial ecosystem services estimate of urban 572 agriculture. Earth's Future 6:40-60. https://doi.org/10.1002/2017EF000536.

573 Coetzee, A., Barnard, P., and Pauw, A. 2018. Urban nectarivorous bird communities in Cape 574 Town, South Africa, are structured by ecological generalisation and resource distribution. 575 Journal of Avian Biology 49:jav-01526. https://doi.org/10.1111/jav.01526. 576 Cohen, H., Philpott, S.M., Liere, H., Lin, B.B., and Jha, S. 2021. The relationship between 577 pollinator community and pollination services is mediated by floral abundance in urban 578 landscapes. Urban Ecosystems 24:275-290. https://doi.org/10.1007/s11252-020-01024-z.

579 Cronk, Q., and Ojeda, I. 2008. Bird-pollinated flowers in an evolutionary and molecular 580 context. Journal of experimental botany 59:715-727. https://doi.org/10.1093/jxb/ern009.

581 Davis, A., Major, R.E., and Taylor, C.E. 2015. The association between nectar availability and 582 nectarivore density in urban and natural environments. Urban Ecosystems 18:503– 583 515.https://doi.org/10.1007/s11252-014-0417-5.

584 De Zeeuw, H., Van Veenhuizen, R., and Dubbeling, M. 2011. The role of urban agriculture in 585 building resilient cities in developing countries. Journal of Agricultural Science 149:153–163. 586 https://doi.org/10.1017/S0021859610001279.

587 Dearborn, D.C., and Kark, S. 2010. Motivations for conserving urban biodiversity. 588 Conservation biology 24:432-440. https://doi.org/10.1111/j.1523-1739.2009.01328.x.

589 Diniz, U. M., Lima, S.A., and Machado, I.C. 2019. Short-distance pollen dispersal by bats in 590 an urban setting: monitoring the movement of a vertebrate pollinator through fluorescent dyes. 591 Urban Ecosystems 22:281-291. https://doi.org/10.1007/s11252-019-0825-7.

592 Dobbs, C., Escobedo, F. J., Clerici, N., de la Barrera, F., Eleuterio, A. A., MacGregor-Fors, I., 593 Reyes-Paecke, S., Vásquez, A., Zea Camaño, J.D., and Hernández, H. J. 2019. Urban 594 ecosystem Services in Latin America: mismatch between global concepts and regional 595 realities? Urban ecosystems 22:173-187. https://doi.org/10.1007/s11252-018-0805-3.

596 Doyle, T., Hawkes, W. L., Massy, R., Powney, G. D., Menz, M. H., and Wotton, K. R. 2020. 597 Pollination by hoverflies in the Anthropocene. Proceedings of the Royal Society B 598 287:20200508. https://doi.org/10.1098/rspb.2020.0508.

599 Du Plessis, M., Seymour, C. L., Spottiswoode, C. N., and Coetzee, A. 2021. Artificial nectar 600 feeders reduce sunbird abundance and plant visitation in Cape Fynbos adjacent to suburban 601 areas. Global Ecology and Conservation 28:e01706. 602 https://doi.org/10.1016/j.gecco.2021.e01706

603 Eggleton, P. 2020. The state of the World's insects. Annual Review of Environment and 604 Resources 45:61-82. https://doi:10.1146/annurev-environ-012420-050035.

605 Fleming, T.H., and Muchhala, N. 2008. Nectar‐feeding bird and bat niches in two worlds: 606 pantropical comparisons of vertebrate pollination systems. Journal of Biogeography 35:764- 607 780. https://doi.org/10.1111/j.1365-2699.2007.01833.x.

608 Fleming, T.H., Geiselman, C., and Kress, W.J. 2009. The evolution of bat pollination: a 609 phylogenetic perspective. Annals of botany 104:1017-1043. 610 https://doi.org/10.1093/aob/mcp197. 611 Frankie, G.W., Thorp, R.W., Hernandez, J., Rizzardi, M., Ertter, B., Pawelek, J. C., Witt, S. 612 L., Schindler, M., and Coville, R. 2009. Native bees are a rich natural resource in urban 613 California gardens. California Agriculture 63:113–120. 614 https://doi.org/10.3733/ca.v063n03p113.

615 Frankie, G.W., Rizzardi, M., Vinson, S.B., and Griswold, T.L. 2009. Decline in bee diversity 616 and abundance from 1972-2004 on a flowering leguminous tree, Andira inermis in Costa Rica 617 at the interface of disturbed dry forest and the urban environment. Journal of the Kansas 618 Entomological Society 82:1–20. http://dx.doi.org/10.2317/JKES708.23.1.

619 Frankie, G.W., Vinson, S.B., Rizzardi, M.A., Griswold, T.L., Coville, R.E., Grayum, M.H., 620 Martinez, L.E.S., Foltz-Sweat, J., and Pawelek, J.C. 2013. Relationships of bees to host 621 ornamental and weedy flowers in urban northwest Guanacaste Province, Costa Rica. Journal 622 of the Kansas Entomological Society 86:325–351. http://dx.doi.org/10.2317/JKES121222.1.

623 Gaston, K. J. 2000. Global patterns in biodiversity. Nature 405:220-227. 624 https://doi.org/10.1038/35012228.

625 Gazola, A.L., and Garófalo, C.A. 2009. Trap-nesting bees (Hymenoptera: Apoidea) in forest 626 fragments of the state of São Paulo, Brazil. Genetics and Molecular Research 8:607-622 627 https://doi.org/10.4238/vol8-2kerr016.

628 Geslin, B., Gauzens, B., Thébault, E., and Dajoz, I. 2013. Plant pollinator networks along a 629 gradient of urbanization. PLoS ONE 8:e63421. https://doi.org/10.1371/journal.pone.0063421.

630 Giannini, T.C., Boff, S., Cordeiro, G.D., Cartolano, E.A., Veiga, A.K., Imperatriz-Fonseca, 631 V.L., and Saraiva, A.M. 2015. Crop pollinators in Brazil: a review of reported interactions. 632 Apidologie 46:209–223. https://doi.org/10.1007/s13592-014-0316-z.

633 Girão, L.C., Lopes, A.V., Tabarelli, M., and Bruna, E.M. 2007. Changes in tree reproductive 634 traits reduce functional diversity in a fragmented Atlantic forest landscape. PLoS ONE 2:e908. 635 https://doi.org/10.1371/journal.pone.0000908.

636 Greig, E.I., Wood, E.M., and Bonter, D.N. 2017. Winter range expansion of a hummingbird is 637 associated with urbanization and supplementary feeding. Proceedings of the Royal Society B: 638 Biological Sciences 284:20170256. https://doi.org/10.1098/rspb.2017.0256.

639 Guenat, S., Kunin, W.E., Dougill, A.J., and Dallimer, M. 2019. Effects of urbanisation and 640 management practices on pollinators in tropical Africa. Journal of Applied Ecology 56:214– 641 224. https://doi.org/10.1111/1365-2664.13270.

642 Hall, D.M., Camilo, G.R., Tonietto, R.K., Ollerton, J., Ahrne, K., Arduser, M., Ascher, J.S., 643 Baldock, K.C.R., Fowler, R., Frankie, G., Goulson, D., Gunnarsson, B., Hanley, M.E., Jackson, 644 J.I., Langellotto, G., Lowenstein, D., Minor, E.S., Philpott, S.M., Potts, S.G., Sirohi, M.H., 645 Spevak, E.M., Stone, G.N., and Threlfall, C.G. 2017. The city as a refuge for insect pollinators. 646 Conservation Biology 31:24–29. https://doi.org/10.1111/cobi.12840. 647 Harrison, T., and Winfree, R. 2015. Urban drivers of plant-pollinator interactions. Functional 648 Ecology 29:879–888. https://doi.org/10.1111/1365-2435.12486.

649 Harrison, T., Gibbs, J., and Winfree, R. 2017. Anthropogenic landscapes support fewer rare 650 bee species. Landscape Ecology 34:967–978. https://doi.org/10.1007/s10980-017-0592-x.

651 Helden, A. J., Stamp, G. C., and Leather, S.R. 2012. Urban biodiversity: comparison of insect 652 assemblages on native and non-native trees. Urban Ecosystems 15:611-624. 653 https://doi.org/10.1007/s11252-012-0231-x.

654 Hennig, E.I., and Ghazoul, J. 2011. Pollinating animals in the urban environment. Urban 655 Ecosystems 15:149–166. https://doi.org/10.1007/s11252-011-0202-7.

656 Hernandez, J.L., Frankie, G., and Thorp, R. 2009. Ecology of Urban Bees: A Review of Current 657 Knowledge and Directions for Future Study. Cities and the Environment 2:1-15. 658 https://doi.org/10.15365/cate.2132009.

659 Hülsmann, M., Von Wehrden, H., Klein, A.M., and Leonhardt, S.D. 2015. Plant diversity and 660 composition compensate for negative effects of urbanization on foraging bumble bees. 661 Apidologie 46: 760–770. https://doi.org/10.1007/s13592-015-0366-x.

662 IPBES - Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. 663 2016. The assessment report of the Intergovernmental Science-Policy Platform on Biodiversity 664 and Ecosystem Services on pollinators, pollination and food production. Potts SG, Imperatriz- 665 Fonseca VL, Ngo HT (Eds). Secretariat of the Intergovernmental Science-Policy Platform on 666 Biodiversity and Ecosystem Services, Bonn, Germany.

667 Kissling, W.D., Sekercioglu, C.H., and Jetz, W. 2012. Bird dietary guild richness across 668 latitudes, environments and biogeographic regions. Global Ecology and Biogeography 21:328- 669 340. https://doi.org/10.1111/j.1466-8238.2011.00679.x.

670 Klein, A.M., Vaissiére, B. E., Cane, J.H., Steffan-Dewenter, I., Cunningham, S.A., Kremen, 671 C., and Tscharntke, T. 2007. Importance of pollinators in changing landscapes for world crops. 672 Proceedings in Biological Sciences/ The Royal Society 274:303–313. 673 https://doi.org/10.1098/rspb.2006.3721.

674 Kobayashi, S., Denda, T., Liao, C.C., Lin, Y.H., Liu, W.T., and Izawa, M. 2018. Comparison 675 of visitors and pollinators of Mucuna macrocarpa between urban and forest environments. 676 Mammal Study 43:219-228. https://doi.org/10.3106/ms2018-0029.

677 Kreft, H., and Jetz, W. 2007. Global patterns and determinants of vascular plant diversity. 678 Proceedings of the National Academy of Sciences 104:5925-5930. 679 https://doi.org/10.1073/pnas.0608361104. 680 Kunz, T.H., Torrez, E.B., Bauer, D., Lobova, T., and Fleming, T.H. 2011. Ecosystem services 681 provided by bats. Annals of the New York Academy of Sciences 1223:1-38. 682 https://doi.org/10.1111/j.1749-6632.2011.06004.x.

683 Lim, V.C., Ramli, R., Bhassu, S., and Wilson, J.J. 2018. Pollination implications of the diverse 684 diet of tropical nectar-feeding bats roosting in an urban cave. PeerJ 6:e4572. 685 https://doi.org/10.7717/peerj.4572.

686 Loram, A., Thompson, K., Warren, P.H., and Gaston, K.J. 2008. Urban domestic gardens (XII): 687 the richness and composition of the flora in five UK cities. Journal of Vegetation Science 688 19:321-330. https://doi.org/10.3170/2008-8-18373.

689 Lowenstein, D.M., Matteson, K.C., and Minor, E.S. 2015. Diversity of wild bees supports 690 pollination services in an urbanized landscape. Oecologia 179:811-821. 691 https://doi.org/10.1007/s00442-015-3389-0.

692 Machado, I.C., and Lopes, A.V. 2004. Floral traits and pollination systems in the Caatinga, a 693 Brazilian tropical dry forest. Annals of Botany 94:365-376. 694 https://doi.org/10.1093/aob/mch152.

695 Maruyama, P.K., Bonizário, C., Marcon, A.P., D'Angelo, G., da Silva, M.M., da Silva Neto, 696 E.N., Oliveira, P.E., Sazima, I., Sazima, M., Vizentin-Bugoni, J., dos Anjos, L., Rui, A.M., and 697 Júnior, O.M. 2019. Plant-hummingbird interaction networks in urban areas: Generalization and 698 the importance of trees with specialized flowers as a nectar resource for pollinator conservation. 699 Biological conservation 230:187-194. https://doi.org/10.1016/j.biocon.2018.12.012.

700 Matias, R., Maruyama, P.K., and Consolaro, H. 2016. A non-hermit hummingbird as main 701 pollinator for ornithophilous plants in two isolated forest fragments of the Cerrados. Plant 702 Systematics and Evolution 302:1217-1226. https://doi.org/10.1007/s00606-016-1327-1.

703 Matteson, K.C., and Langellotto, G.A. 2010. Determinates of inner city butterfly and bee 704 species richness. Urban Ecosystems 13:333-347. https://doi.org/10.1007/s11252-010-0122-y.

705 Matteson, K.C., and Langellotto, G.A. 2011. Small scale additions of native plants fail to 706 increase beneficial insect richness in urban gardens. Insect Conservation and Diversity 4:89- 707 98. https://doi.org/10.1111/j.1752-4598.2010.00103.x.

708 Matteson, K.C., Grace, J.B., and Minor, E.S. 2013. Direct and indirect effects of land use on 709 floral resources and flower-visiting insects across an urban landscape. Oikos 122:682–694. 710 https://doi.org/10.1111/j.1600-0706.2012.20229.x.

711 McDonald, R.I., Mansur, A.V., Ascensão, F., Crossman, K., Elmqvist, T., Gonzalez, A., 712 Güneralp, B., Haase, D., Hamann, M., Hillel, O., Huang, K., Kahnt, B., Maddox, D., Pacheco, 713 A., Pereira, H.M., Seto, K.C., Simkin, R., Walsh, B., Werner, A.S and Ziter, C. 2020. Research 714 gaps in knowledge of the impact of urban growth on biodiversity. Nature Sustainability 3:16- 715 24. https://doi.org/10.1038/s41893-019-0436-6. 716 Meehan, T.D., Dale, K., Lebaron, G.S., Rowden, J., Michel, N.L., Wilsey, C.B., and Langham, 717 G.M. 2020. Interacting with hummingbirds at home: Associations with supplemental feeding, 718 plant diversity, plant origin, and landscape setting. Landscape and Urban Planning 719 197:103774. https://doi.org/10.1016/j.landurbplan.2020.103774.

720 Michener, Charles Duncan. 2007. The Bees of the World. Baltimore: Johns Hopkins University 721 Press.

722 Millard, J., Outhwaite, C. L., Kinnersley, R., Freeman, R., Gregory, R. D., Adedoja, O., ... and 723 Newbold, T. 2021. Global effects of land-use intensity on local pollinator biodiversity. Nature 724 Communications, 12: 2902. https://doi.org/10.1038/s41467-021-23228-3

725 Miller, J.R., and Hobbs, R.J. 2002. Conservation where people live and work. Conservation 726 biology 16:330-337. https://doi.org/10.1046/j.1523-1739.2002.00420.x.

727 Montoya-Pfeiffer, P.M., Rodrigues, R.R., and Alves dos Santos, I. 2020. Bee pollinator 728 functional responses and functional effects in restored tropical forests. Ecological Applications 729 30:e02054. https://doi.org/10.1002/eap.2054.

730 Muchhala, N., and Thomson, J.D. 2010. Fur versus feathers: Pollen delivery by bats and 731 hummingbirds and consequences for pollen production. The American Naturalist 175:717– 732 726. https://doi.org/10.1086/652473.

733 Nascimento, V.T., Agostini, K., Souza, C.S., and Maruyama, P.K. 2020. Tropical urban areas 734 support highly diverse plant-pollinator interactions: An assessment from Brazil. Landscape and 735 Urban Planning 198:103801. https://doi.org/10.1016/j.landurbplan.2020.103801.

736 Nemésio, A., and Silveira, F.A. 2007. Orchid bee fauna (Hymenoptera: Apidae: Euglossina) 737 of Atlantic Forest fragments inside an urban area in southeastern Brazil. Neotropical 738 Entomology 36:186–191. https://doi.org/10.1590/S1519-566X2007000200003.

739 Nemésio, A., and Silveira, F.A. 2010. Forest Fragments with Larger Core Areas Better Sustain 740 Diverse Orchid Bee Faunas (Hymenoptera: Apidae: Euglossina). Neotropical Entomology 741 39:555-561. https://doi.org/10.1590/S1519-566X2010000400014.

742 Nicholls, E., Ely, A., Birkin, L., Basu, P., and Goulson, D. 2020. The contribution of small- 743 scale food production in urban areas to the sustainable development goals: A review and case 744 study. Sustainability Science 15:1585–1599. https://doi.org/10.1007/s11625-020-00792-z.

745 Oliveira, M.T.P., Silva, J.L.S., Cruz-Neto, O, Borges, L.A., Girão, L.C., Tabarelli, M. and 746 Lopes, A.V. 2020. Urban green areas retain just a small fraction of tree reproductive diversity 747 of the Atlantic forest. Urban Forestry and Urban Greening 54: 126779.

748 Oliveira, R., Pinto, C.E., and Schlindwein, C. 2015. Two common species dominate the 749 species-rich Euglossine bee fauna of an Atlantic Rainforest remnant in Pernambuco, Brazil. 750 Brazilian Journal of Biology 75:1-8. http://dx.doi.org/10.1590/1519-6984.18513. 751 Oliveira, W., Silva, J.L.S., Oliveira, M.T.P., Cruz-Neto, O., Silva, L.A.P., Borges, L.A., 752 Sobrinho, M.S., and Lopes, A.V. 2019. Reduced reproductive success of the endangered tree 753 brazilwood (Paubrasilia echinata, Leguminosae) in urban ecosystem compared to Atlantic 754 forest remnant: lessons for tropical urban ecology. Urban Forestry and Urban Greening 755 41:303–312. https://doi.org/10.1016/j.ufug.2019.04.020.

756 Ollerton, J. 2017. Pollinator diversity: distribution, ecological function, and conservation. 757 Annual Review of Ecology, Evolution, and Systematics 48:353–376. 758 https://doi.org/10.1146/annurev-ecolsys-110316- 022919.

759 Ollerton, J., Winfree, R., and Tarrant, S. 2011. How many flowering plants are pollinated by 760 animals? Oikos 120: 321-326. https://doi.org/10.1111/j.1600-0706.2010.18644.x.

761 Orr, M.C., Hughes, A.C., Chesters, D., Pickering, J., Zhu, C.D., and Ascher, J.S. 2021. Global 762 patterns and drivers of bee distribution. Current Biology 31:451-458. 763 https://doi.org/10.1016/j.cub.2020.10.053.

764 Orsini, F., Kahane, R., Nono-Womdim, R., and Giaquinto, G. 2013. Urban agriculture in the 765 developing world: A review. Agronomy for Sustainable Development 33:695–720. 766 https://doi.org/10.1007/s13593-013-0143-z.

767 Osborne, J.L., Martin, A.P., Shortall, C.R., Todd, A.D., Goulson, D., Knight, M.E., Hale, R.J., 768 and Sanderson, R.A. 2008. Quantifying and comparing bumblebee nest densities in gardens 769 and countryside habitats. Journal of Applied Ecology 45:784–792. 770 https://doi.org/10.1111/j.1365-2664.2007.01359.x.

771 Pardee, G.L., and Philpott, S.M. 2014. Native plants are the bee’s knees: local and landscape 772 predictors of bee richness and abundance in backyard gardens. Urban Ecosystems 17:641-659. 773 https://doi.org/10.1007/s11252-014-0349-0.

774 Pauw, A., and Louw, K. 2012. Urbanization drives a reduction in functional diversity in a guild 775 of nectar-feeding birds. Ecology and Society 17:27 http://dx.doi.org/10.5751/ES-04758- 776 170227.

777 Pellissier, V., Muratet, A., Verfaillie, F., and Machon, N. 2012. Pollination success of Lotus 778 corniculatus (L.) in an urban context. Acta Oecologia 39:94–100. 779 https://doi.org/10.1016/j.actao.2012.01.008.

780 Porto, R.G., Almeida, R. F., Cruz-Neto, O., Tabarelli, M., Viana, B. F., and Lopes, A.V. 2020. 781 Pollination ecosystem services: A comprehensive review of economic values, research funding 782 and policy actions. Food Security, 12:1425-1442. https://doi.org/10.1007/s12571-020-01043- 783 w.

784 Possamai, B.T., Dec, E., and Mouga, D.S.M. 2017. Bee community and trophic resources in 785 Joinville, Santa Catarina. Acta Biológica Catarinense 4:29-41. 786 https://doi.org/10.21726/abc.v4i1.360 787 Potter, A., and G. LeBuhn. 2015. Pollination service to urban agriculture in San Francisco, CA. 788 Urban Ecosystems 18:885–893. https://doi.org/10.1007/s11252-015-0435-y.

789 Potts, S.G., Biesmeijer, J.C., Kremen, C., Neumann, P., Schweiger, O., and Kunin,W.E. 2010. 790 Global pollinator declines: Trends, impacts and drivers. Trends in Ecology and Evolution 791 25:345–353. https://doi.org/10.1016/j.tree.2010.01.007.

792 Potts, S.G., Imperatriz-Fonseca, V., Ngo, H.T., Aizen, M.A., Biesmeijer, J. C., Breeze, T. D., 793 Dicks, L.V., Garibaldi, L.A., Hill, R., Settele, J., and Vanbergen, A.J. 2016. Safeguarding 794 pollinators and their values to human well-being. Nature 540:220-229. 795 https://doi.org/10.1038/nature20588.

796 Puga-Caballero, A., Arizmendi, M.D.C., and Sanchez-Gonzalez, L.A. 2020. Phylogenetic and 797 phenotypic filtering in hummingbirds from urban environments in Central Mexico. 798 Evolutionary Ecology 34:525-541. https://doi.org/10.1007/s10682-020-10055-z.

799 Ratto, F., Simmons, B. I., Spake, R., Zamora‐Gutierrez, V., MacDonald, M. A., Merriman, J. 800 C., Tremlett, C.J., Poppy, G.M., Peh, K.S.H., and Dicks, L.V. 2018. Global importance of 801 vertebrate pollinators for plant reproductive success: a meta‐analysis. Frontiers in Ecology and 802 the Environment 16:82-90. https://doi.org/10.1002/fee.1763.

803 Rech, A.R., Dalsgaard, B., Sandel, B., Sonne, J., Svenning, J.C., Holmes, N., and Ollerton, J. 804 2016. The macroecology of animal versus wind pollination: ecological factors are more 805 important than historical climate stability. Plant Ecology & Diversity 9:253-262. 806 https://doi.org/10.1080/17550874.2016.1207722.

807 Rocha-Filho, L.C., Ferreira-Caliman, M.J., Garófalo, C.A., and Augusto, S.C. 2018. A 808 specialist in an urban area: are cities suitable to harbour populations of the oligolectic bee 809 Centris (Melacentris) collaris (Apidae: Centridini)? Annales Zoologici Fennici 55:135–149. 810 https://doi.org/10.5735/086.055.0101.

811 Rodrigues, L.C., and Araujo, A.C. 2011. The hummingbird community and their floral 812 resources in an urban forest remnant in Brazil. Brazilian Journal of Biology 71:611-622. 813 http://dx.doi.org/10.1590/S1519-69842011000400005.

814 Rosas‐Guerrero, V., Aguilar, R., Martén‐Rodríguez, S., Ashworth, L., Lopezaraiza‐Mikel, M., 815 Bastida, J.M., and Quesada, M. 2014. A quantitative review of pollination syndromes: do floral 816 traits predict effective pollinators? Ecology letters 17:388-400. 817 https://doi.org/10.1111/ele.12224

818 Sandström U.G., Angelstam, P., and Mikusiński, G. 2006. Ecological diversity of birds in 819 relation to the structure of urban green space. Landscape and urban planning 77: 39-53. 820 https://doi.org/10.1016/j.landurbplan.2005.01.004. 821 Seto, K.C., Güneralp, B., and Hutyra, L.R. 2012. Global forecasts of urban expansion to 2030 822 and direct impacts on biodiversity and carbon pools. Proceedings of the National Academy of 823 Sciences 109:16083-16088. https://doi.org/10.1073/pnas.1211658109.

824 Seto, Karen., Parnell, Susan., and Elmqvist, Thomas. 2013. A global outlook on urbanization. 825 In Urbanization, Biodiversity and Ecosystem Services: Challenges and Opportunities – A 826 Global Assessment, ed. Springer, 1-12. Dordrecht.

827 Silva, F.D.S., Carvalheiro, L.G., Aguirre-Gutiérrez, J., Lucotte, M., Guidoni-Martins, K., and 828 Mertens, F. 2021b. Virtual pollination trade uncovers global dependence on biodiversity of 829 developing countries. Science Advances 7:eabe6636. https://doi.org/10.1126/sciadv.abe6636.

830 Silva, J.L.S., de Oliveira, M.T.P., Cruz-Neto, O., Tabarelli, M., and Lopes, A.V. 2021a. Plant– 831 pollinator interactions in urban ecosystems worldwide: A comprehensive review including 832 research funding and policy actions. Ambio 50:884–900. https://doi.org/10.1007/s13280-020- 833 01410-z.

834 Silva, J.L.S., Oliveira, M.T.P., Oliveira, W., Borges, L.A., Cruz-Neto, O., and Lopes, A.V. 835 2020. High richness of exotic species in tropical urban green spaces: Reproductive systems, 836 fruiting and associated risks to native species. Urban Forestry and Urban Greening 50:126659. 837 https://doi.org/10.1016/j.ufug.2020.126659.

838 Smith, R. M., Warren, P.H, Thompson, K., and Gaston, K.J. 2006. Urban domestic gardens 839 (VI): Environmental correlates of invertebrate species richness. Biodiversity and Conservation 840 15:2415–2538. https://doi.org/10.1007/s10531-004-5014-0.

841 Sritongchuay, T., Hughes, A.C., and Bumrungsri, S. 2019. The role of bats in pollination 842 networks is influenced by landscape structure. Global Ecology and Conservation 20: e00702. 843 https://doi.org/10.1016/j.gecco.2019.e00702.

844 Spotswood, E.N., Beller, E.E., Grossinger, R., Grenier, J.L., Heller, N.E., and Aronson, M.F.J. 845 2021. The biological deserts fallacy: cities in their landscapes contribute more than we think to 846 regional biodiversity. BioScience 71:148–160. https://doi.org/10.1093/biosci/biaa155.

847 Stewart, A.B., Sritongchuay, T., Teartisup, P., Kaewsomboon, S., and Bumrungsri, S. 2018. 848 Habitat and landscape factors influence pollinators in a tropical megacity, Bangkok, Thailand. 849 PeerJ 6: e5335. https://doi:10.7717/peerj.5335.

850 Stewart, A.B., and Waitayachart, P. 2020. Year-round temporal stability of a tropical, urban 851 plant-pollinator network. PLoS one 15:e0230490. 852 https://doi.org/10.1371/journal.pone.0230490.

853 Taki, H., Ikeda, H., Nagamitsu, T., Yasuda, M., Sugiura, S., Maeto, K., and Okabe, K. 2017. 854 Stable nitrogen and carbon isotope ratios in wild native honeybees: the influence of land use 855 and climate. Biodiversity and Conservation 26:3157-3166. https://doi.org/10.1007/s10531- 856 016-1114-x. 857 Tangtorwongsakul, P., Warrit, N., and Gale, G.A. 2018. Effects of landscape cover and local 858 habitat characteristics on visiting bees in tropical orchards. Agricultural and Forest 859 Entomology 20: 28–40. https://doi.org/10.1111/afe.12226.

860 Theodorou, P., Radzevičiūtė, R., Lentendeu, G., Kahnt, B., Husemann, M., Bleidorn, C., 861 Settele, J., Schweiger, O., Grosse, I., Wubet, T., and Murray, T.E., Paxton, R. J. 2020. Urban 862 areas as hotspots for bees and pollination but not a panacea for all insects. Nature 863 Communications 11:576. https://doi.org/10.1038/s41467-020-14496-6.

864 Tripp, E.A., and Manos, P.S. 2008. Is floral specialization an evolutionary dead‐end? 865 Pollination system transitions in Ruellia (Acanthaceae). Evolution: International Journal of 866 Organic Evolution 62:1712-1737. https://doi.org/10.1111/j.1558-5646.2008.00398.x.

867 Turo, K.J., and Gardiner, M.M. 2019. From potential to practical: conserving bees in urban 868 public green spaces. Frontiers in Ecology and the Environment 17:167-175. 869 https://doi.org/10.1002/fee.2015.

870 Van Veenhuizen, René. 2006. Cities farming for the future, urban agriculture for green and 871 productive cities. Philippines: RUAF Foundation, IDRC and IIRR.

872 Viotti, M.A., Moura, F. R., and Lourenço, A.P. 2013. Species Diversity and Temporal 873 Variation of the Orchid-Bee Fauna (Hymenoptera, Apidae) in a Conservation Gradient of a 874 Rocky Field Area in the Espinhaço Range, State of Minas Gerais, Southeastern Brazil. 875 Neotropical Entomology 42:565–575. https://doi.org/10.1007/s13744-013-0164-y.

876 Wayo, K., Sritongchuay, T., Chuttong, B., Attasopa, K., and Bumrungsri, S. 2020. Local and 877 landscape compositions influence stingless bee communities and pollination networks in 878 tropical mixed fruit orchards, Thailand. Diversity 12:482. https://doi.org/10.3390/d12120482.

879 Wee, A.K., Low, S.Y., and Webb, E.L. 2015. Pollen limitation affects reproductive outcome 880 in the bird-pollinated mangrove Bruguiera gymnorrhiza (Lam.) in a highly urbanized 881 environment. Aquatic Botany 120:240-243. https://doi.org/10.1016/j.aquabot.2014.09.001.

882 Wenzel, A., Grass, I., Belavadi, V.V., and Tscharntke, T. 2020. How urbanization is driving 883 pollinator diversity and pollination – A systematic review. Biological Conservation 884 241:108321. https://doi.org/10.1016/j.biocon.2019.108321.

885 Whelan, C.J., Wenny, D.G., and Marquis, R.J. 2008. Ecosystem Services Provided by Birds. 886 Annals of the New York Academy of Sciences 1134:25–60. 887 https://doi.org/10.1196/annals.1439.003.

888 Whelan, C.J., Şekercioğlu, Ç.H., and Wenny, D.G. 2015. Why birds matter: from economic 889 ornithology to ecosystem services. Journal of Ornithology 156:227–238. 890 https://doi.org/10.1007/s10336-015-1229-y. 891 Wojcik, V.A., and McBride, J.R. 2012. Common factors influence bee foraging in urban and 892 wildland landscapes. Urban Ecosystems 15:581–598. https://doi.org/10.1007/s11252-011- 893 0211-6.

894 Zanata, T.B., Dalsgaard, B.O., Passos, F.C., Cotton, P.A., Roper, J.J., Maruyama, P. K., ... and 895 Varassin, I.G. 2017. Global patterns of interaction specialization in bird–flower networks. 896 Journal of Biogeography 44: 1891-1910. https://doi.org/10.1111/jbi.13045.

897 Zanette, L.R.S., Martins, R.P., and Ribeiro, S.P. 2005. Effects of urbanization on Neotropical 898 wasp and bee assemblages in a Brazilian metropolis. Landscape and Urban Planning. 71:105– 899 121. https://doi.org/10.1016/j.landurbplan.2004.02.003.

900 Zattara, E.Z., and Aizen, M.A. 2021. Worldwide occurrence records suggest a global decline 901 in bee species richness. One Earth 4:114-123. https://doi.org/10.1016/j.oneear.2020.12.005.

902 Zhao, C., Sander, H. A., and Hendrix, S. D. 2019. Wild bees and urban agriculture: assessing 903 pollinator supply and demand across urban landscapes. Urban Ecosystems 22:455–470. 904 https://doi.org/10.1007/s11252-019-0826-6.