Common Visitors Research Articles

Constructed floating wetlands made of natural materials as habitats in eutrophicated coastal lagoons in the Southern Baltic Sea

Eutrophication remains an environmental challenge in lagoons along the Southern Baltic Sea. Floating islands planted with emergent macrophytes are an option to remove nutrients from eutrophicated waters. Furthermore, floating wetlands offer other ecosystem services such as the provision of habitats. Numerous scientific studies have been conducted; however most remain on the laboratory scale. This research explores the challenges associated with installations in coastal environments and focuses on sustainability of the island design, the habitat function as well as nutrient removal. Most floating wetland designs use polyethylene, polypropylene, polyurethane or polyvinyl alcohol foam to ensure the buoyancy. For this study an artificial polymer free island design was developed and tested. The floating constructions in the Darss-Zingst-Bodden-Chain were planted with native macrophytes which have the potential to act as ‘biodiversity-supplements’ to the adjacent coastal wetlands: Bolboschoenus maritimus, Carex acutiformis, Iris pseudacorus, Juncus effesus, Lythrum salicaria, Schoenoplectus lacustris, Typha latifolia. The chosen macrophytes survived fluctuating salinities. After three months the above-ground biomass was harvested and analyzed for the nutrient concentrations. Phosphorus concentrations were highest in L. salicaria and nitrogen in I. pseudacorus. Video monitoring and field observations were applied in order to observe animals. Birds did not use the floating wetlands as breeding grounds, but the grey heron (Ardea cinerea) was a common visitor for foraging. Especially surprising was the large amount of juvenile eels (Anguilla anguilla). A diverse and large root network below the floating islands boosts not only nutrient removal but serves as a shelter and refuge for fish such as the endangered eel.

Rabbit health and welfare

As the third most popular pet species behind dogs and cats, rabbits will be a common visitor to your clinic. Claire Speight, speaking at the BVNA online Congress in October 2020, reminds us of the specialist management of rabbits.

Foraging Behavior and Pollen Transport by Flower Visitors of the Madeira Island Endemic Echium candicans.

Simple SummaryThe successful conservation of many endangered island plants depends on the pollination services provided by animals. In this study, we identify the flower visitors of Echium candicans, a charismatic plant exclusive to the island of Madeira, and also evaluate their performance as pollinators by analyzing their behavior on the flowers and the pollen they transport on their body. We found that many different animals visit this plant’s flowers, from insects to reptiles, but bees were the most frequent visitors. Large bees visited more flowers and transported more pollen of Echium candicans compared to other pollinators, like butterflies and hoverflies. However, by visiting many flowers in the same plant large bees might contribute to inbreeding, whilst the other animals visited fewer flowers in each plant favoring outcrossing. We conclude that the different flower visitors of Echium candicans provide complementary services as pollinators and highlight the importance of having diverse communities of pollinators to ensure successful pollination in many island plants.The study of flower visitor behavior and pollen transport dynamics within and between plants can be of great importance, especially for threatened or rare plant species. In this work, we aim to assess the flower visitor assemblage of the Madeiran endemic Echium candicans and evaluate the performance of the most common visitors through the analysis of their foraging behavior and pollen loads. The flower visitor assemblage of E. candicans is diverse, including several insect groups and the endemic lizard Teira dugesii, but bees are the most common visitors. In general, large bees (Amegilla quadrifasciata, Apis mellifera, and Bombus spp.) had the highest average visitation rates (>18 flowers/min) and their pollen loads had higher percentages of homospecific pollen (>66%) when compared with butterflies and hoverflies. The honeybee (Apis mellifera) and two bumblebees (Bombus terrestris and B. ruderatus) were the most efficient flower visitors of E. candicans, but their foraging behavior seems to favor geitonogamy. Other visitors, such as butterflies and the small bee Lasioglossum wollastoni, may have a complementary role to the honeybee and bumblebee species, as their high mobility is associated with fewer flower visits on each plant and may promote xenogamy. Two non-native bees (A. mellifera and B. ruderatus) are important flower visitors of E. candicans and may contribute mostly to self-pollination rendering the endemic plant more vulnerable to inbreeding effects.

Pollination ecology and breeding systems of Cypripedium kentuckiense (Orchidaceae) in Tennessee1

The orchid Cypripedium kentuckiense is listed as imperiled in Tennessee and Oklahoma and critically imperiled in seven other states. We followed individuals' vegetative and floral traits over two seasons. Patterns of floral senescence were found to vary over two seasons and might be related to April temperatures when buds develop. Mechanical self-pollination was uncommon but perhaps “leaky.” Frequencies of insect-mediated pollination were surprisingly high (62%) for a Cypripedium species with large flowers but conversion of flowers into fruit was low (7% and 14%), suggesting that cryptic factors lower reproductive success, not inadequate pollinator visits. Hand-pollinations suggest flowers are self-compatible. As in other Cypripedium species, floral architecture relates to pollinator dimensions but at this site, only two bee species, Anthophora abrupta and A. bomboides, were primary pollinators. Male A. abrupta were common visitors although male bees are uncommon pollen vectors of Cypripedium species. For the first time, exit patterns of bees inside Cypripedium flowers were recorded based on bee species and gender. This behavior varied and was somewhat atypical of previous studies on other bee-pollinated species in the clade and genus. Specifically, Anthophora species within labella chewed on the epidermis lingering within the interior and exit canals. Consequently, C. kentuckiense might not be a trap.

Hydrogel baits pose minimal risk to non‐target insects and beneficial species

AbstractInvasive ants are a significant pest around the world and have negative impact on natural and agricultural environments. Chemical control is mainly accomplished with residual sprays and toxic baits. Hydrogel baits are a novel bait formulation that has proven highly effective against multiple invasive ant species, but potential non‐target effects have not been investigated. The baits are typically saturated in 25% sucrose solution which makes them attractive to foraging ants and potentially non‐target organisms such as pollinators. The objective of the current study was to perform field studies to assess the potential attractiveness of hydrogel baits to various pollinating and non‐pollinating arthropods in a variety of ecosystems, including tallgrass prairies, urban pollinator gardens, and commercial apiaries. The study focused on social Hymenoptera as pesticides are acutely toxic to various Hymenoptera and have been implicated as one of the contributing factors in pollinator declines. Results show that Diptera were overwhelmingly the most common visitors and accounted for >40% of all visitors. Other common groups included beetles and yellowjackets. Common pollinating insects such as honeybees, solitary bees, and butterflies rarely visited the baits and accounted for ca. 3% of all visits and were never found on ground baits. Results show that the risk to pollinators is relatively low; most arthropods attracted to the baits were taxa that are extremely abundant, not of conservation concern, and in some cases pestiferous or invasive. The deployment of hydrogels for invasive ant control in areas where multiple invasive insect taxa are present may have the additional benefit of controlling multiple pests.

Floral Visitors to Helianthus verticillatus, a Rare Sunflower Species in the Southern United States

Helianthus verticillatus Small (whorled sunflower) is a federally endangered plant species found only in the southeastern United States that has potential horticultural value. Evidence suggests that H. verticillatus is self-incompatible and reliant on insect pollination for seed production. However, the identity of probable pollinators is unknown. Floral visitors were collected and identified during Sept. 2017 and Sept. 2018. Thirty-six species of visitors, including 25 hymenopterans, 7 dipterans, 2 lepidopterans, and 2 other insect species, were captured during 7 collection days at a site in Georgia (1 day) and 2 locations in Tennessee (6 days). Within a collection day (0745–1815 hr), there were either five or six discrete half-hour collection periods when insects were captured. Insect visitor activity peaked during the 1145–1215 and 1345–1415 hr periods, and activity was least during the 0745–0845 and 0945–1015 hr periods at all three locations. Visitors were identified by genus and/or species with morphological keys and sequences of the cox-1 mitochondrial gene. The most frequent visitors at all sites were Bombus spp. (bumblebees); Ceratina calcarata (a small carpenter bee species) and members of the halictid bee tribe Augochlorini were the second and third most common visitors at the two Tennessee locations. Helianthus pollen on visitors was identified by microscopic observations and via direct polymerase chain reaction of DNA using Helianthus-specific microsatellites primers. Pollen grains were collected from the most frequent visitors and Apis mellifera (honeybee) and counted using a hemocytometer. Based on the frequency of the insects collected across the three sites and on the mean number of pollen grains carried on the body of the insects, Bombus spp., Halictus ligatus (sweat bee), Agapostemon spp., and Lasioglossum/Dialictus spp., collectively, are the most probable primary pollinators of H. verticillatus.

Pollen Loads of Flower Visitors to Açaí Palm (Euterpe oleracea) and Implications for Management of Pollination Services.

Understanding the functional roles of different pollinator species is crucial to the development of sustainable farming practices in pollinator-dependent crops. However, this can be challenging for crop plants in tropical regions with hyper-diverse pollinator communities. Here, we assess pollen loads of different insect visitors to inflorescences of açaí palm (Euterpe oleracea), the most important native crop in the Amazon estuary region. Flower-visiting insects were collected from pistillate (female) inflorescences at eight sites, including four managed floodplain forests and four plantations. Pollinator Importance Value Index (PIVI) and Relative Importance (RI) scores were calculated for common visitor taxa (≥ 10 individuals) using sum visit frequencies and median pollen loads. Pollen load analyses revealed that over seventy insect taxa, including bees, flies, beetles, wasps and ants, were effective vectors of E. oleracea pollen. Native bees, including both solitary and eusocial taxa, were the most efficient pollen vectors, with median pollen loads at least eight times higher than those of the next best insect group (flies). Insect pollen loads were at their highest between 0800 and 1300 hours, and four insect taxa had RI scores > 0.05, including two meliponine bees belonging to the Trigona genus (Trigona branneri Cockerell and Trigona pallens Fabricius) and two halictid bee genera (Augochloropsis and Dialictus). Our results suggest that native bees play an important role in açaí pollination and should be the primary focus of pollinator management in açaí production systems.

Pollinator Communities of Restored Sandhills: a Comparison of Insect Visitation Rates to Generalist and Specialist Flowering Plants in Sandhill Ecosystems of Central Florida

Globally, urbanization and other forms of land use change have been implicated in widespread pollinator declines and disruptions to plant–pollinator interactions. A growing body of literature, however, suggests that urban habitat fragments can provide oases for both plant and insect diversity. A micro-ecosystem on our college campus was created to represent the longleaf pine savannas (sandhills) that once dominated upland ridges throughout the Southeast. To assess the ability of this site to support wild insect pollinators, from May through August for three years (2016–2018) we compared visitation to two abundant flowering plant species, Bidens alba (a generalist-pollinated composite) and Chamaecrista fasciculata (a specialist-pollinated legume), between the campus micro-ecosystem and a nearby site within a large conservation area containing sandhill habitat undergoing restoration. We found that, for both plant species, total insect visitation rates did not differ between years or sites, suggesting that the small urban fragment is capable of maintaining abundant pollinators. The identity of generalist visitors to Bidens alba, however, differed dramatically between sites. Wild hymenopterans constituted more than two-thirds of all insect visits in the campus site but less than half in the conservation area, where butterflies, flies, and beetles were also common visitors. The high density of flowers in the campus site is likely at least partially responsible for the high abundance of hymenopterans, a result consistent with that of many other studies showing that hymenopterans are less sensitive to urbanization than are other insect groups.

Observation of Flower Visitors to Determine their Potential Role as Pollinators of Ixora coccinae and Ruellia simplex

This study aimed to determine the potential pollinating agents of Ixora coccinae and Ruellia simplex at Universiti Malaysia Terengganu (UMT) campus based on the foraging activities of the flower visitors. The diurnal observations (0700 hr to 1800 hr) were conducted for a total of 144 hours and 96 hours for I. coccinae, for R. simplex respectively. The flower visitor activities (landing or hovering at the flowers) and the time spent at the flowers however were recorded for only the first 10 minutes of every hour between 0700 hr and 1000 hr for four days. A total of 383 flower visitations was recorded by 17 insect species and a bird species, the olive-backed sunbird (Cinnyris jugularis). For I. coccinae, the most common visitors were Apis cerana, Heterotrigona itama and Xylocopa confusa, in which all species were found to show only landing behaviour to forage at the flowers, and the time spent foraging at the flowers was not significantly different between the species (Kruskal-Wallis test, H = 1.323, df = 2, p = 0.055). For R. simplex, the most common visitors were A. cerana with 100% landing, and C. jugularis which recorded 80% landing and 20% hovering during their visits to the flowers. Between the two, A. cerana recorded significantly longer time spent at the flowers as compared to C. jugularis (Mann-Whitney test, U = 17.355, p < 0.001). Based on the visitation rate and feeding behaviour of the flower visitors, A. cerana, H. itama and X. confusa were the potential pollinating agents for I. coccinae while for R. simplex, A. cerana showed higher potential to be a pollinating agent as compared to C. jugularis. Therefore, this study highlighted the importance of recording the behaviour of each flower visitor to determine the relative contribution to the pollination success of the plant species visited.

Non-Bee Insects as Visitors and Pollinators of Crops: Biology, Ecology, and Management

Insects other than bees (i.e., non-bees) have been acknowledged as important crop pollinators, but our understanding of which crop plants they visit and how effective they are as crop pollinators is limited. To compare visitation and efficiency of crop-pollinating bees and non-bees at a global scale, we review the literature published from 1950 to 2018 concerning the visitors and pollinators of 105 global food crops that are known to benefit from animal pollinators. Of the 105 animal-pollinated crops, a significant proportion are visited by both bee and non-bee taxa (n = 82; 77%), with a total gross domestic product (GDP) value of US$780.8 billion. For crops with a narrower range of visitors, those that favor non-bees (n = 8) have a value of US$1.2 billion, compared to those that favor bees (n = 15), with a value of US$19.0 billion. Limited pollinator efficiency data were available for one or more taxa in only half of the crops (n = 61; 58%). Among the non-bees, some families were recorded visiting a wide range of crops (>12), including six families of flies (Syrphidae, Calliphoridae, Muscidae, Sarcophagidae, Tachinidae, and Bombyliidae), two beetle families (Coccinelidae and Nitidulidae), ants (Formicidae), wasps (Vespidae), and four families of moths and butterflies (Hesperiidae, Lycaenidae, Nymphalidae, and Pieridae). Among the non-bees, taxa within the dipteran families Syrphidae and Calliphoridae were the most common visitors to the most crops, but this may be an artifact of the limited data available. The diversity of species and life histories in these groups of lesser-known pollinators indicates that diet, larval requirements, and other reproductive needs will require alternative habitat management practices to bees.

Bats and moths contribute to the reproductive success of the columnar cactus Pilosocereus leucocephalus

The pollination systems of columnar cacti in the dry tropics are often thought to be highly specialized to bats. This specialization is generally inferred when flowers that are only exposed to the activity of nocturnal visitors set fruit and seed. Although moths are also common visitors to the flowers of columnar cacti at night, it is generally thought that their contribution to the reproductive success of this cactus is negligible. Using selective exclusions, we assessed the contribution of bats and moths to the reproductive success in a population of Pilosocereus leucocephalus in central Mexico. Fruit set was 100% for bat-pollinated flowers and 34% in moth-pollinated flowers. Seed number per fruit was 1473 in bat-pollinated and 836 in moth pollinated flowers. Our results clearly show that in addition to bats, moths are effective pollinators of Pilosocereus leucocephalus in the study area. Therefore, bats are the main pollinators of P. leucocephalus, and moths are the secondary pollinators.

Variation in pollinator potential to carry a blueberry fungal pathogen and assessment of transfer efficiency in two managed bee species

Plant diseases are ubiquitous in agricultural systems and are major sources of economic loss. Vaccinium corymbosum, or highbush blueberry, is an economically important crop affected by an insect-vectored, fungal pathogen, Monilinia vaccinii-corymbosi, or mummy berry disease. Highbush blueberry yield is maximized through outcrossed pollination; however, the pathogen is vectored by pollinators. We used field collections and molecular techniques to identify floral visitors to highbush blueberry and quantify levels of pathogen spores carried by each visiting species. We also conducted a cage trial using single flower visits to determine differences in vectoring efficiency between two managed pollinators, Apis mellifera and Bombus impatiens. We found that bees, flies, and wasps were all common visitors, and that all bee species and several fly and wasp species carried the pathogen. Of the bee species, A. mellifera most often tested positive for the pathogen, while Dolichovespula maculata (Bald-faced Hornet) tested positive most among wasps and Mallota posticata among flies. Considering only individuals that tested positive, mummyberry levels per individual were highest in D. maculata and Andrena bees, and relatively low in flies. In cage trials, we found no differences between A. mellifera and B. impatiens in pathogen load or transfer efficiency, suggesting that these managed species are equally capable of vectoring mummyberry during a single visit to a blighted stem and then a flower. This research demonstrates the variety of floral visitors that carry mummyberry and that two common commercial pollinator species have similar potential to vector mummyberry to blueberry flowers during a single visit.

Contribution of bees and other pollinators to watermelon (Citrullus lanatus Thunb.) pollination

Watermelon (Citrullus lanatus Thunb.) is an important economic crop with 29.6 million tons produced worldwide. However, few native bees and other pollinators have been documented to visit watermelon flowers and the contribution of these insects to watermelon pollination has yet to be determined. We examined 40 commercial watermelon fields from 2013 to 2016 and obtained information on pollinator visitation rates for managed and wild pollinators at different distances from field margins. We determined the amount of pollen on common pollinators’ bodies, how much time these pollinators spent on flowers, and the amount of pollen they deposited on stigmas. Forty-three species of potential pollinators were documented during the 4-year study. Managed honey bees (Apis mellifera L.) were the most common visitor, but numerous other pollinators (e.g., Agapostemon splendens Lepeletier, Campsomeris plumipes var. fossulana Fabricius) were found to be abundant. This sweat bee and scoliid wasp carried as much watermelon pollen as worker A. mellifera did. No differences were detected among visitation rates among various taxonomic groups at different distances (0, 25, 50, 100 m) from field margins except for small bees (e.g., Lasioglossum, Halictus), which were found in higher abundances at the field margins. Managed and wild bumble bees (Bombus spp.) were not common visitors of watermelons and may not be a good surrogate for managed honey bees. Overall, numerous insect species contribute to watermelon pollination. Therefore, watermelon growers should consider future land-use changes or other management practices that might positively affect the abundances of bee and wasp species.

Stay awhile in my burrow! Interspecific associations of vertebrates to Indian crested porcupine burrows

The Indian crested porcupine, Hystrix indica, is a significant ecosystem engineer that builds extensive burrows in the semi-arid regions of north-west India. Many different animals use these burrows as temporary retreats or permanent shelters. Camera-traps were used to record 22 species using porcupine burrows, including 10 mammals, 8 birds, 3 reptiles, and 1 amphibian. In addition to birds foraging inside and around the entrance, the most common and persistent visitors were mongooses, rats, squirrels, hares, jungle cats, and small Indian civets. A bat species, Hipposideros sp. was found to be permanent occupants of porcupine burrows, while Indian rock pythons and jackals exhibited seasonal use. During winter, pythons basked outside the burrows and constricted their activities to the daytime. Conversely, porcupines are nocturnal and use deeper parts of their burrows than the pythons. Temporal usage patterns and spatial segregation allows for mutualistic behaviour between pythons and porcupines. Jackals were also found to use porcupine burrows during their summer breeding season, employing aggression to evict both porcupines and pythons. The study demonstrates a functional role for porcupines, which are capable of constructing “landmark” structures in the semi-arid regions of north-west India that support a range of micro-communities.

Foraging behavior and pollination of carpenter bees Xylocopa spp. (Hymenoptera: Apidae).

Large carpenter bees (the genus Xylocopa), as an important group of bees (Apidae), are common visitors to flowering plants in tropics and subtropics. Their foraging behavior is characterized by long season of activity, high diversity of foraging plants, tolerance of high temperatures, activity under low illumination levels, and buzz pollination. These traits make them to be attractive pollinators for agricultural pollination in hot climates, especially in greenhouses, night-blooming plants, and some Solanum. In recent years, large carpenter bees have been demonstrated have efficient pollination service in blueberries, passion flower, runner bean, greenhouse tomatoes and greenhouse melons in foreign countries. However, evidence for their importance and effectiveness as crop pollinators is lacking for most plant species in China. This article reviewed the research progress on foraging behavior and pollination of Xylocopa, with the aim to provide a theoretical basis for the conservation management and utilization of large carpenter bees.

Investigating tangential access for location-based digital cultural heritage applications

As location-based digital cultural heritage applications are beginning to be applied outside ‘traditional’ cultural heritage sites, there is an increased need to consider their use amongst people who may be interested in the cultural heritage of a site, but have that interest as a tangential, opportunistic, aspect of their visit. We outline why this is important, and present issues in evaluating it. We then introduce Explore: a mobile, location-based, digital cultural heritage application for the Finnish recreational island of Seurasaari. By considering how the common visitor trajectory of a museum visit can be mapped onto a visit to the island, we were able to evaluate Explore with participants who were not primarily there to access cultural heritage. Evaluation with 45 participants over 5 days identified how the low immersion techniques used allowed participants to fit accessing cultural heritage around their visit, how participants managed group tension between those more and those less interested in Explore, as well as issues around considering the use of cultural heritage applications as a tangential purpose of a visit.

Micromorphological and histochemical attributes of flowers and floral reward in Linaria vulgaris (Plantaginaceae)

The self-incompatible flowers of Linaria vulgaris have developed a range of mechanisms for attraction of insect visitors/pollinators and deterrence of ineffective pollinators and herbivores. These adaptive traits include the flower size and symmetry, the presence of a spur as a “secondary nectar presenter,” olfactory (secondary metabolites) and sensual (scent, flower color, nectar guide—contrasting palate) signals, and floral rewards, i.e. pollen and nectar. Histochemical tests revealed that the floral glandular trichomes produced essential oils and flavonoids, and pollen grains contained flavonoids, terpenoids, and steroids, which play a role of olfactory attractants/repellents. The nectary gland is disc-shaped and located at the base of the ovary. Nectar is secreted through numerous modified stomata. Nectar secretion began in the bud stage and lasted to the end of anthesis. The amount of produced nectar depended on the flower age and ranged from 0.21 to 3.95 mg/flower (mean = 1.51 mg). The concentration of sugars in the nectar reached up to 57.0%. Both the nectar amount and sugar concentration demonstrated a significant year and population effect. Pollen production was variable between the years of the study. On average, a single flower of L. vulgaris produced 0.31 mg of pollen. The spectrum of insect visitors in the flowers of L. vulgaris differed significantly between populations. In the urban site, Bombus terrestris and Apis mellifera were the most common visitors, while a considerable number of visits of wasps and syrphid flies were noted in the rural site.

Ants contribute to pollination but not to reproduction in a rare calcareous grassland forb.

The number of plants pollinated by ants is surprisingly low given the abundance of ants and the fact that they are common visitors of angiosperms. Generally ants are considered as nectar robbers that do not provide pollination service. We studied the pollination system of the endangered dry grassland forb Euphorbia seguieriana and found two ant species to be the most frequent visitors of its flowers. Workers of Formica cunicularia carried five times more pollen than smaller Tapinoma erraticum individuals, but significantly more viable pollen was recovered from the latter. Overall, the viability of pollen on ant cuticles was significantly lower (p < 0.001)—presumably an antibiotic effect of the metapleural gland secretion. A marking experiment suggested that ants were unlikely to facilitate outcrossing as workers repeatedly returned to the same individual plant. In open pollinated plants and when access was given exclusively to flying insects, fruit set was nearly 100%. In plants visited by ants only, roughly one third of flowers set fruit, and almost none set fruit when all insects were excluded. The germination rate of seeds from flowers pollinated by flying insects was 31 ± 7% in contrast to 1 ± 1% resulting from ant pollination. We conclude that inbreeding depression may be responsible for the very low germination rate in ant pollinated flowers and that ants, although the most frequent visitors, play a negligible or even deleterious role in the reproduction of E. seguieriana. Our study reiterates the need to investigate plant fitness effects beyond seed set in order to confirm ant-plant mutualisms.

Aggregate enantiostyly: Floral visitor interactions with a previously unreported form of floral display

Floral herkogamy, or the spatial separation of reproductive structures, plays an important role in the evolution of plant mating systems. One form of herkogamy is enantiostyly, or the alternate presentation of stigmas to the left and right of the floral axis. Theoretically, enantiostyly increases outcrossing rate by promoting reciprocal pollen deposition and export, but empirical evidence of this is lacking. Understanding how pollinators interact with enantiostylous flowers will illuminate the mechanisms by which enantiostyly encourages outcross pollination. We quantified style deployment within and among plants, of Allionia incarnata L. (Nyctaginaceae), a species with a new kind of enantiostyly we call “aggregate enantiostyly”. A. incarnata is the first species known to have “compound blossoms”, with different flowers each containing a left- or right-handed style. We quantify the autonomous selfing rate and describe floral visitor interactions with this unique floral structure. We found equal frequency of left- and right-handed blossoms within and among plants. Common floral visitors, Hemiargus ceraunus and Halictus sp., interacted with either anthers or stigmas, but not both, indicating effective outcrossing at the flower level. Outcrossing produced more fruits than selfing. The order in which floral visitors interacted with reproductive structures indicates that enantiostyly may increase pollen export. However, we did not find evidence that enantiostyly affected pollen deposition. Our study provides an intriguing first look at the reproductive ecology of a species with a new unique form of herkogamy, and provides evidence on the adaptive significance of enantiostyly.

Insect pollination improves yield of Shea (&lt;i&gt;Vitellaria paradoxa&lt;/i&gt; subsp. &lt;i&gt;paradoxa&lt;/i&gt;) in the agroforestry parklands of West Africa

Pollinator decline, driven primarily by habitat degradation, has the potential to reduce the quantity and quality of pollinator-dependent crops produced across the world. Vitellaria paradoxa, a socio-economically important tree which grows across the sub-Saharan drylands of Africa, produces seeds from which shea butter is extracted. However, the habitats in which this tree grows are threatened with degradation, potentially impacting its ability to attract sufficient pollinators and to produce seeds. The flowers of V. paradoxa are insect-pollinated, and we investigated flower visitors in six sites in southern Burkina Faso and northern Ghana and tested whether plants were capable of fruit set in the absence of pollinators. We found that the majority of flower visitors (88%) were bees, most frequently small social stingless bees (Hypotrigona gribodoi), but native honey bees (Apis mellifera adansonii) were also common visitors to flowers early in the morning. The number of fruit produced per inflorescence was significantly lower when insects were excluded during flowering by bagging, but any fruits and seeds that were produced in bagged treatments were of similar weight to un-bagged ones. We conclude that conservation of habitat to protect social bees is important to maintain pollination services to V. paradoxa and other fruit-bearing trees and cultivated crops on which local livelihoods depend.