Species Of Floral Visitors Research Articles

Bat or bee pollination? Floral biology of two sympatric Cayaponia species (Cucurbitaceae) in Southeast Brazil

The evolution of pollination systems is unclear for many plant taxa due to the scarcity of field observations on floral visitors. Supposed bat- and bee-pollination is reported for species of the genus Cayaponia, but <5 % of these were observed in the field and their pollinators recorded. We studied the pollination biology of two early diverging sister species of Cayaponia, C. cabocla and C. pilosa, recording the floral biology, phenology, breeding system, floral visitors, and floral scent chemistry. Both species are monoecious and have bell-shaped white to greenish flowers. The length of the C. cabocla flowers was 2.33 ± 0.52 cm and of the C. pilosa flowers it was 2.75±0.95 cm. In C. cabocla nectar volume of male flowers was 180±57.15 μl and sugar concentration was 28.75±0.95%, whereas in female flowers the average volume was 46.5 ± 10.24 μl and sugar concentration was 22.5 ± 0.57%. Cayaponia cabocla flowers opened at late night, around 03:30 h, whereas those of C. pilosa opened around noon. Both species bloom in the austral summer (January-February) and depend on bees to set fruit, in addition to having a few floral visitor species in common. Whereas some of the flower traits resemble those of bat-pollinated plants (most notably the large nectar volume and nocturnal anthesis), the floral volatiles of both C. cabocla and C. pilosa are typical of flowers pollinated by bees. This study clarifies the pollination system of two Cayaponia species and provides new information that can be used to reconstruct pollination system transitions in this rich genus of cucurbits.

Elevational and seasonal patterns of plant pollinator networks in two highland tropical ecosystems in Costa Rica.

Many plant species in high montane ecosystems rely on animal pollination for sexual reproduction, however, our understanding of plant-pollinator interactions in tropical montane habitats is still limited. We compared species diversity and composition of blooming plants and floral visitors, and the structure of plant-floral visitor networks between the Montane Forest and Paramo ecosystems in Costa Rica. We also studied the influence of seasonality on species composition and interaction structure. Given the severe climatic conditions experienced by organisms in habitats above treeline, we expected lower plant and insect richness, as well as less specialized and smaller pollination networks in the Paramo than in Montane Forest where climatic conditions are milder and understory plants are better protected. Accordingly, we found that blooming plants and floral visitor species richness was higher in the Montane Forest than in the Paramo, and in both ecosystems species richness of blooming plants and floral visitors was higher in the rainy season than in the dry season. Interaction networks in the Paramo were smaller and more nested, with lower levels of specialization and modularity than those in the Montane Forest, but there were no seasonal differences within either ecosystem. Beta diversity analyses indicate that differences between ecosystems are likely explained by species turnover, whereas within the Montane Forest differences between seasons are more likely explained by the rewiring of interactions. Results indicate that the decrease in species diversity with elevation affects network structure, increasing nestedness and reducing specialization and modularity.

Pan traps: An effective tool for monitoring phenological changes in insect floral visitors and their relationship with floral resources in a coastal Mediterranean forest

Precise monitoring of insect floral visitors and their relationship with floral resources throughout the flowering season provides baseline information to help us understand long-term changes in plant-pollinator interactions and improve pollinator conservation strategies. Pan traps are one of the methods most used for monitoring insect floral visitors and several studies have already linked the abundance and richness of these floral visitors with floral resources. However, less research has been conducted into the effectiveness of pan traps for monitoring phenological changes in the floral visitor community with regard to floral resources. We used pan traps to study the species composition and the abundance of insect floral visitors and their relationship with flower richness in a coastal forest throughout the entire flowering season for two consecutive years. Captures were confirmed to be floral visitors through field survey studies. Pan traps were effective for revealing changes in the abundance and species composition of floral visitor communities during and between years that correlated with changes in floral richness and species composition. Changes in floral visitor abundance showed a different bias in their association with floral richness. Thus, while Hymenoptera and Diptera abundance tended to be negatively correlated with floral richness, Coleoptera abundance tended to be positively correlated, although such correlations could change from year to year. There were two significantly different groups of flowering plant and floral visitor species: one in spring and the other in summer. Each period was characterized by unique overlap between some floral visitors and their floral resources, suggesting that to monitor floral visitors effectively both communities need to be considered. Interestingly, the floral phenology in this coastal forest extended longer than that of more inland communities, so reliable monitoring of floral visitors throughout the floral season may help us to better understand the role of coastal plant communities in the stabilization of the pollinator networks of more inland communities. Overall, phenology patterns need to be taken into account for pan trapping to become an effective methodology for monitoring floral visitor communities, considering both intra-year (spring and summer communities) and inter-year variations.

Manipulating network connectance by altering plant attractiveness.

Mutualistic interactions between plants and their pollinating insects are critical to the maintenance of biodiversity. However, we have yet to demonstrate that we are able to manage the structural properties of these networks for the purposes of pollinator conservation and preserving functional outcomes, such as pollination services. Our objective was to explore the extent of our ability to experimentally increase, decrease, and maintain connectance, a structural attribute that reflects patterns of insect visitation and foraging preferences. Patterns of connectance relate to the stability and function of ecological networks. We implemented a 2-year field experiment across eight sites in urban Dublin, Ireland, applying four agrochemical treatments to fixed communities of seven flowering plant species in a randomized block design. We spent ~117 h collecting 1,908 flower-visiting insects of 92 species or morphospecies with standardized sampling methods across the 2 years. We hypothesized that the fertilizer treatment would increase, herbicide decrease, and a combination of both maintain the connectance of the network, relative to a control treatment of just water. Our results showed that we were able to successfully increase network connectance with a fertilizer treatment, and maintain network connectance with a combination of fertilizer and herbicide. However, we were not successful in decreasing network connectance with the herbicide treatment. The increase in connectance in the fertilized treatment was due to an increased species richness of visiting insects, rather than changes to their abundance. We also demonstrated that this change was due to an increase in the realized proportion of insect visitor species rather than increased visitation by common, generalist species of floral visitors. Overall, this work suggests that connectance is an attribute of network structure that can be manipulated, with implications for management goals or conservation efforts in these mutualistic communities.

Temporal variation of a plant-floral visitor network in a temperate forest in Michoacán, Mexico

The ecological network approach allows the analysis of interactions between plant communities and their floral visitors. However, most floral visitation network studies analyze the interactions with a temporally-static perspective. Hence, few studies have evaluated the temporal variation of these systems. This study characterized the plant-floral visitor interaction network of a temperate forest remnant in Michoacán, analyzing monthly changes in its composition, structure, and dynamics during 3 seasons of the year. In total, we recorded 1,325 floral visits and 131 links between 27 plant species and 74 floral visitor species. Most of the plant species observed belong to the families Lamiaceae, Asteraceae, and Apiaceae, while most of the floral visitor species observed belong to the orders Hymenoptera, Lepidoptera, and Diptera. Most of the floral visits were recorded in highly abundant plant species with longer flowering periods at the study site. The constant species turnover gave rise to monthly plant-floral visitor networks with different levels of specialization, connectance, nestedness, and modularity. Our results suggest that plant-floral visitor networks in temperate forest remnants are highly dynamic and poorly connected, which makes them vulnerable to drastic changes in the environment.

Pollinator Diversity and Pollination Efficiency of Stingless Bee &lt;i&gt;Tetragonula iridipennis&lt;/i&gt; Smith in Bitter Gourd

An experiment was conducted out to investigate the pollinator diversity and pollination efficiency of Tetragonula iridipennis Smith on bitter gourd (Momordica charantia L.). In this study, there were 16 floral visitor species were recorded. Among them, six species were the most frequent visitors. A highest mean of visits was recorded with Halictus sp. (7.80) during 1000-1200 hrs in relative abundance and the lowest was of Megachile sp. (2.90) at 1600-1800 hrs. The foraging rate of stingless bees was most active in morning 1000-1200 hrs. The maximum fruit set was observed in pollinator-imposed fields (80.23 %) compared to pollinator excluded fields (71.15 %). Prominent increase in fruit length and girth in the pollinator included plots were respectively observed to be 249.19 and 42.91 mm. Maximum number of fruit/ individual plant (24.10) was achieved with bee pollination as compared to control (21.20).

Pollination Potentiality of Honey Bee (Apis cerana Fab.) in Sunflower Hybrid (DRSH-1) Seed Production

The study was conducted at Main Agricultural Research Station, UAS, Raichur during rabi 2020-21 to utilize honey bees in sunflower hybrid seed production. Totally, thirty species of floral visitors were recorded on parental lines of sunflower hybrid (DRSH-1), among them 15 were hymenopterans, 7 lepidopterans, 5 coleopterans and 3 dipterans. Apis cerana was predominant pollinator (17.91±6.72 bees/ 5 capitula/ 5 min) on CMS parental line (ARM-243), followed by A. dorsata and least was A. florea. The peak foraging activity of A. dorsata was recorded at 0900-1000 hr with 24 bees, A. cerana recorded two peak foraging activity, one at 1100-1200 hr (29 bees) and another at 1600-1700 hr (18 bees) and A. florea recorded at 1000-1100 hr (10 bees). The maximum Shannon-Wiener index of diversity (H=1.32) of floral visitors on CMS line under open condition was recorded at 0800-0900 hr of the day and least (H=0.84) was at 1600-1700 hr. In case of fertility restorer line (6D-1) maximum Shannon-Wiener index was recorded at 1600-1700 hr (1.24). A. cerana under caged condition (three colonies per acre) without pollen load on CMS line were recorded highest mean number of nectar foragers (65±22.60 bees), followed by A. dorsata, A. cerana and A. florea foragers from natural colonies in open pollination condition. Whereas, highest mean number of nectar foragers (42.25±23.59) with pollen load in A. cerana under caged condition (three colonies per acre) were recorded, followed by A. dorsata, A. cerana and A. florea. Nectar foragers with pollen load on CMS line play an important role in transfer of pollen grains from restorer line to CMS line and carry out effective pollination. A. florea with and without pollen load spent more foraging duration (13.17 and 25.20 sec/capitulum respectively) on CMS line, followed by A. cerana and least in case of A. dorsata in open pollination. Bees without pollen load spent significantly greater nectar foraging duration as compared with bees with pollen load, both in caged and open pollination situations. Significantly highest seed yield per hectare (839.53 kg), per cent filled seeds (95.80 %), test weight (5.41 g), volume weight (46.41 g/100 ml), kernel percentage (66.09 %), highest kernel to husk ratio (1.94) and highest seed quality and associated parameters were recorded in hand + open pollinated plots, followed by the A. cerana @ 3 colonies per acre treated plots, hand pollination, open pollination and least seed quality parameters were recorded in control treatment.

Biología floral, sistema reproductivo y visitantes florales de Vitex cymosa (Lamiaceae)

Vitex cymosa Bert. ex Spreng. (Lamiaceae) is a native species of tropical and subtropical Central and South America. Its medicinal, antioxidant, antifungal and antibacterial properties are noteworthy and widely studied. This study aims to contribute towards the knowledge of the reproductive biology of V. cymosa, through: the determination of the reproductive system; the description of reproductive morphological attributes (flower, fruit, pollen and nectary), attractants and floral phases, as well as the record and function of floral visitors. Vitex cymosa presents melitophilic floral traits: diurnal anthesis, bluish coloration, bilabiate structural type, presence of visual guides in the corolla indicating the location of the reward (nectar), and a soft, sweet and pleasant aroma to humans. The pollen has pollenkit and is deposited nototribically on the pollinators. The nectary is of gynoecial origin, the nectar is released through nectarostomes located on the apex of the ovary, remaining available even after corolla abscition, as a post-floral nectary; such zone is distinguished by a purple coloration, different from that of the rest of this organ, which grows basipetally as the fruit develops. The reproductive system of V. cymosa is mixed, resulting in more than 75% of fructification, through both allogamy mediated by pollinators and spontaneous self-pollination, presenting a slight hercogamy that would contribute to cross-pollination. Eleven species of floral visitors were recorded, all belonging to the Class Insecta. Among these floral visitors, Apis mellifera was the most frequent species, and along with other species of native bees (of the genera Bombus, Centris, Plebeia, Tetragonisca, Trigona), wasps and butterflies, they would be pollinators when they visit legitimately (in the case of the hymenopterans, as some of them thieve pollen). Despite this visitor assembly, the most important pollinators are the bees, which coincides with the melitophilic characteristics of the flowers. The nectar exposed in flowers where the corolla has already fallen, more accessible to some bees and to the wasps, would contribute to greater attraction to pollinators, as well as predatory insects of herbivores of the developing fruits.

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Effect of drought stress on the foraging behavior of insect pollinators and the reproductive success of canola (Brassica napus L.)

To appraise the effect of drought stress on the foraging behavior (visitation frequency and visitation rate) of insect pollinators and its ultimate impact on reproductive success of canola (Brassica napus L.), an experiment was carried out at the Research Farm of MNSUniversity of Agriculture, Multan, Pakistan. Previously, only a few studies have evaluated drought stress as a predictor of plant-pollinator interactions. Normal irrigated and drought stress plots of canola were separated by a distance of fifteen meters. Normal irrigated plots received recommended number of irrigations (three times) i.e., 1st irrigation at 30 days after germination (DAG), 2nd at flowering, and 3rd at pod setting. However, irrigation was applied only once to drought-stressed plots i.e., 1st irrigation at 30 DAG. Twelve insect species in two orders and five families visited the canola flowers. These floral visitor species were grouped into three categories, i.e., Apis bees (honey bees), non-Apis bees, and flies. The abundance of Apis and non-Apis bees was significantly higher in irrigated plots than in drought plots, while the abundance of flies did not differ significantly in both plots. Stay time of all the floral visitors was significantly higher in drought plots, while the visitation rate was significantly higher in irrigated plots. The interaction between pollination modes (open pollination and self-pollination) and water regimes (normal irrigation and drought stress) was significant for all the reproductive success parameters of canola (silique length and weight, number of seeds per silique, seed weight per silique, number of siliques per plant and fatty acid contents (%) of canola seeds) under normal irrigation regime for free insect visits treatment. Moreover, a variation of 83% to 207% was observed for these parameters between irrigated and drought plots receiving insect pollination (free insect visits) due to higher pollinator abundance and visitation rate in the former ones. However, all the reproductive success parameters did not vary between irrigated and drought plots with no insect pollination (no insect visits, caged treatment). In conclusion, drought stress negatively affected insect pollinators’ foraging behavior, leading to low reproductive success in canola. In the climate change scenario and limited water availability, future studies should consider drought stress for other cross-pollinated crops under varying environments and pollinator fauna.

Leaf beetle herbivory shapes the subsequent flower-visiting insect community and impacts plant reproduction

ABSTRACT Herbivory can induce changes in flower traits influencing the community of flower-visiting insects and ultimately impacting the plant’s reproductive output. Here, we investigated how leaf herbivory on sweet pepper plants, Capsicum annuum L., by Diabrotica speciosa (Germar) adults influences the community of insect floral visitors and alters plant reproduction. In an experimental field, we found that flowers of herbivore-infested plants were less visited by insects than those of uninfested plants. A similar pattern was found for the abundance of the three most common species of floral visitors in the collections, Apis mellifera (Linnaeus), Toxomerus sp.1, and Trigona spinipes (Fabricius). The insect community associated with the flowers of herbivore-infested plants was distinct, less rich, and diverse than that of uninfested plants. Leaf herbivory also impacted flower abundance that likely influenced the visual attraction of insects. The changes in flower-visiting insect community associated with herbivore-infested plants coincided with a reduced number of fruits, which were smaller and contained fewer seeds than those from uninfested plants. Our results suggest that leaf herbivory by D. speciosa results in direct and indirect costs to the plants through modifications in abundance and composition of flower-visiting insect community.

Global meta‐network of legume crops and floral visitors reveals abundance of exotic bees

AbstractLegume crops (family Fabaceae, order Fabales) constitute a relevant component of the human food supply. In view of the global decline in crop production, as a result of increasing threats (such as habitat fragmentation and land use change) to pollinators, knowledge concerning legume floral visitors can contribute to world food security. In this study, a synthesis was performed of global data on interactions between legume crops and their floral visitors, in order to improve understanding of the structure of crop‐floral visitor interactions and the roles of different species. A literature review was conducted using three databases, considering 15 legumes of economic importance, enabling the construction of a meta‐network of plant‐floral visitor interactions. Soybean, alfalfa and common bean received the highest numbers of floral visitor species. A total of 208 floral visitor species were recorded, distributed in eight orders. The most diverse group was Hymenoptera (mainly bees), followed by Lepidoptera. The European honeybee Apis mellifera interacted with the highest number of plant species. Modularity analysis identified eight modules that included more than one order of floral visitors. Most species were classified as peripherals, with few links restricted to their own module. The three connector species were the bees Bombus pascuorum, B. terrestris and Megachile rotundata. The only network hub was A. mellifera. The predominance of bees seemed to be related to the predominant floral morphology among the crops. The connector and hub species were typically generalists, and all except one species (B. pascuorum) were used as managed pollinators. The crops studied have an important role in global pollination resilience, maintaining a diversified fauna of pollinators other than bees.

Consequences of the high abundance of Bombus terrestris on the pollination of Vicia faba

One of the main visitors to Fabia bean crops (Vicia faba) in South America is the invasive bumblebee species Bombus terrestris. This is particularly true in Chile, where B. terrestris was first introduced in 1997 and is now common over much of the country. In this study, we evaluated the activity of the principal pollinators of V. faba over two cropping seasons by assessing their visitation rates while distinguishing between legitimate visits, likely to lead to pollination, and nectar robbery. We then determined the net contribution of insect visitation on pod and seed set. We recorded seven species of floral visitors. Most visits (legitimate visits and robbery) were from the honeybee (Apis mellifera), with B. terrestris being the next most common visitor. In the case of B. terrestris, 87.19% of visits were nectar robbery. On average, the same flower perforation was visited 23 times by B. terrestris during the flower's lifespan. In general, the frequency of legitimate visits varied with pollinator identity and year. For B. terrestris, each flower received an average of 0.95 legitimate visits during its entire lifespan. The time spent by B. terrestris visiting flowers for both nectar robbery or pollen collection decreased after the first day of flowering suggesting resource depletion. The number of pods, total seed number, and seed weight were lower where self rather than open pollination. This suggests that open pollination increased reproductive success. We conclude that B. terrestris was likely to contribute relatively little to pollination while at the same time depleting floral resources throughout the flowers’ lifespan.

Assessment of interactions between oil flowers and floral visitors in world biomes

Abstract Specialized glands that produce and store floral oil are found in 11 families of flowering plants, with greater representation in Malpighiaceae. Solitary bees use this resource to feed larvae and for cell lining. Oil interactions have been reported mainly at the population level and in some community studies that have commonly ignored not only the fewer representative families of oil-offering flowers, but also the floral visitors that do not collect floral oil. We have compiled and examined the interactions between oil-offering flowers and floral visitors in world biomes, to describe the structural patterns of the oil interaction meta-network and evaluate the species' functional roles. We reviewed 169 studies, which mainly used a phytocentric approach, reporting 1460 interactions between 214 species of oil-offering flowers and 377 species of floral visitors. Malpighiaceae and bees (mainly oil-collecting bees) were the most frequently investigated. The meta-network of oil interactions showed a modular structure, mainly influenced by botanical families, and core–periphery organization. The most important functional roles were associated with Malpighiaceae and oil-collecting bees, possibly due to their representativeness and geographic distribution.

Divergent pollination system and morph-dependent effects of corolla length on inaccuracy of reciprocity and reproductive success of a distylous species of Rubiaceae

Intraspecific floral variations may affect the degree of generalization and efficacy of pollinators, with consequences for plant reproductive success. Such effects could be greater for heterostylous plants because morphological variation can alter reciprocity between morphs. We evaluated the frequency, composition, and efficacy of pollinators, and the reciprocity (measured by population inaccuracy) of Psychotria nuda, a distylous species of Rubiaceae, in a montane forest. Moreover, we assessed the effects of corolla length on reciprocity and reproductive success. We recorded eighteen species of floral visitors, belonging to four functional groups. The frequency of visits differed among groups with butterflies being the most frequent visitors, in contrast to hummingbird-pollinated lowland populations. This difference did not affect reproductive success, since fruit set was similar between these populations. The total population inaccuracy was 21.56 mm2, with inaccuracy of low organs being higher (12.03 mm²) than that of high organs (9.53 mm²). Floral traits may have different effects on the reproductive success of morphs of distylous species; the corolla length of P. nuda only affected the reproductive success of short-styled flowers. Large corollas showed greater reproductive success and lower individual inaccuracies for this morph, indicating compensation for the effects of imperfect reciprocal herkogamy on reproductive success.

Pollinator Efficacy in Yellow Passion Fruit (Passiflora edulis f. flavicarpa Deg., Passifloraceae).

A pollinator's efficacy is the result obtained from a single visit by a species and is often used to measure the importance of different species of floral visitors as pollinators. Therefore, this study aimed to measure the efficacy of fruit and seed set in Passiflora edulis f. flavicarpa Deg. (Passifloraceae) by manual cross-pollination, natural pollination and by Xylocopa (Neoxylocopa) frontalis (Olivier 1789), performed through a single and two visits, to evaluate if there is occurrence of pollen limitation and pollinators' limitation in the studied crop fields. Four different treatments were performed: (1) manual cross-pollination (n = 37 flowers); (2) natural pollination (n = 52 flowers); (3) pollination by a single visit of X. frontalis (n = 41 flowers); and (4) pollination by two visits of X. frontalis (n = 31 flowers). We verified that fruit set occurred in all the treatments performed. Fruit set rate by manual cross-pollination was significantly higher than that obtained under natural conditions indicating the occurrence of pollen limitation and pollinators' limitation under natural pollination. Regarding the number of seeds, analysis of variance (ANOVA) did not indicate a significant difference between the mean seed set for the different types of pollination evaluated. The management of occupied nests, the introduction of trap-nests, and the conservation of native vegetation in areas close to the yellow passion fruit crops can increase pollinators' population. The greater richness and abundance of pollinators are essential to promote a greater number of fruit and seed set in the yellow passion fruit crops.

Wild bee pollination in Grewia flavescens Juss.

Grewia flavescens Juss. is an underutilised fruit species found throughout semi-arid and sub-humid parts of the world including India. For the first time, an attempt was made to study the role of different flower visitors on fruit set of G. flavescens. We have recorded different floral visitors, activity patterns, foraging behavior and their role in fruit set. A total of 25 species of floral visitors were recorded, of which Megachilidae (48.35%) was the most abundant group followed by Apidae (27.21%), Halictidae (10.29%) and others (14.15%). Among floral visitors, the foraging rate and foraging speed of Megachile and Xylocopa were studied. They were also effective in depositing more pollen on the stigmatic surface per visit than other flower visitors. Fruit-set was higher (71.42%) in open pollinated flowers than in artificial-cross pollinated (68.33%). Whereas, artificially-selfed and pollinator excluded flowers resulted in the lowest fruit-set (22.22% and 8.95%, respectively). G. flavescens is a self-compatible species but favouring cross pollination and also exhibited delayed self pollination to ensure reproductive success in the absence of an effective pollinator.

Non‐native plants and nitrogen addition have little effect on pollination and seed set in 3‐year‐old restored woodland

AbstractHuman activities can disrupt the insect pollination process, which can trigger a decline in pollination and plant reproductive output. Floral visitors are not equally effective pollinators, and it is unknown how multiple changes to an environment further change the effectiveness of insect pollination for native plants. We investigated how herbicide treatment, the presence of non‐native plants and addition of nitrogen fertiliser change the relative importance of different species of floral visitors to four native plant species: Callistemon phoeniceus, Calothamnus quadrifidus, Hakea lissocarpha and Banksia sessilis. Our field site was a large‐scale revegetation site in south‐west Western Australia in which the presence of non‐native plants and nitrogen deposition were experimentally manipulated. Experimental exclusion of floral visitors revealed pollinators were likely required for the seed set of three of the native species, and none of the four plant species were pollen‐limited. We observed 8936 floral visitors of 249 morphospecies from 14 insect orders on four native and two non‐native plant species. From PIV calculations, 57% of floral visitors were potential pollinators, with the remainder considered just visitors due to their low Pollinator Importance Value (PIV). The introduced Apis mellifera (European honey bee, Apidae) was the most frequent floral visitor and the most effective pollinator of all four native plant species. The presence of two non‐native plant species and addition of nitrogen fertiliser did not affect the effectiveness of the potential pollinators, or the viable seeds produced by the four native plant species.

Tropical urban areas support highly diverse plant-pollinator interactions: An assessment from Brazil

Urban areas contribute to conservation of pollinators, but we lack assessments from the most biodiverse tropical regions in the world. We synthesized studies on urban plant-pollinator interactions across Brazil, compiling 86 studies conducted in urban green spaces that reported 2678 interactions for 519 plant and 337 animal species. We evaluated the spatio-temporal distribution of the data, effects of sampling and conducted interaction network analyses. Most studies were conducted after the 2000s, in highly urbanized Atlantic Forest areas, with overrepresentation of large public institution areas. Most studies are of difficult access to the international audience as they were published in Portuguese and in local journals. Around 60% of the plants associated to pollinators are native while only three floral visitor species were categorized as exotic. Bees were the most diverse group and had the highest number of interacting plants, but avian and mammal pollinators were also found in urban areas. Hence, many native pollinators benefit from urban floral resources. Sampling effort and method impacted the number of interaction partners recovered, indicating the need for complementary and better planned sampling protocols. Mostly herbs and shrubs acted as network hubs across Brazilian urban landscapes, so these life forms are important to support pollinators and should be promoted for this purpose. We advocate for better standardized and planned research on urban plant-pollination interactions in diverse tropical countries, in order to accomplish a truly global effort on conservation of pollinators in urban areas.

Flowering and pollination ecology of Cleistocactus baumannii (Cactaceae) in the Brazilian Chaco: pollinator dependence and floral larceny

ABSTRACT Cleistocactus baumannii is the only ornithophilous cactus species in the Brazilian Chaco. In addition, this species of Cactaceae invests heavily in flowering in the ecoregion. Such characteristics motivated us to evaluate the temporal availability of flowers in the context of its floral visitors. The reproductive system of C. baumannii, the number of individuals in flowering, flower abundance and the frequency and richness of floral visitors were evaluated and quantified. Nectar robbery was a frequent phenomenon in the studied population; therefore, we compared the pollen load deposited on the stigma of damaged (robbery) and undamaged flowers. In the Brazilian Chaco, C. baumannii is self-incompatible and has a continuous flowering pattern, providing floral resources throughout the year for nine species of floral visitors. One hummingbird species acted as a potential pollinator, and we consider Xylocopa splendidula to be a nectar robber. We found stigma of flowers damaged by nectar robbers to have lower pollen loads than those of undamaged flowers. This study highlights the importance of studying reproductive traits in different populations to understand changes in the reproductive success of plant species at different scales and possible causes, such as availability of floral visitors, incidence of robbers and flowering patterns.