Pollination Biology Research Articles

The Nighttime Fragrance of Guettarda scabra (Rubiaceae): Flower Scent and Its Implications for Moth Pollination.

Floral scent is crucial for attracting pollinators, especially in plants that bloom at night. However, chemical profiles of flowers from nocturnal plants with varied floral morphs are poorly documented, limiting our understanding of their pollination ecology. We investigated the floral scent in Guettarda scabra (L.) Vent. (Rubiaceae), a night-blooming species with short- and long-styled floral morphs, found in the threatened pine rocklands in south Florida, US. By using dynamic headspace sampling and GC-MS analysis, we characterized the chemical profiles of the floral scent in both morphs. Neutral red staining was also employed to determine the specific floral regions responsible for scent emission in G. scabra. The results revealed that G. scabra's fragrance consists entirely of benzenoid and terpenoid compounds, with benzeneacetaldehyde and (E)-β-ocimene as dominant components. There were no differences in the chemical profiles between the long- and short-styled flowers. Staining assays indicated that the corolla lobes, anthers, and stigma were the primary sources of the scent. These findings indicate that G. scabra's floral scent is consistent with that of night-blooming plants pollinated by nocturnal hawkmoths, providing important insights into its chemical ecology and pollinator attraction. This study demonstrates how floral scent chemistry can validate predictions based on flower morphology in hawkmoth-pollinated plants.

Phenology, floral organs ultra-structure, traits correlation, stigma receptiveness, pollen viability and germinability in horsegram (Macrotyloma uniflorum Lam.) Verdc.

The absence of information on the reproductive biology of some nutritive legumes has been an obstacle to their genetic improvement. Gathering information on reproductive biology contributes significantly to the interest of breeders to have adequate tools for initiating the improvement program through crosses among high performing genotypes. To contribute to this, we examined the flowering phenology, pollen biology, stigma receptiveness at bud dehiscence and anthesis phases, and the in-vitro germination of the pollens in horsegram (Macrotyloma uniflorum). Pollens of horsegram were found to be either tricolporate or triporate, echinates in all accessions except in the collections from Benin. Ovaries in horsegram showed great variation in the number of ovules and activities of peroxidase indicated the receptiveness of stigma at bud dehiscence phase and during anthesis. A high number of ovules per ovary was found in accessions from Australia (Leichardt 1 and 2), Mali (LeichardtMali) and India (CPI22679). Pollen viability analysis implies the possibility of better results when pollinating during the day and immediately after the flower opens. The study provides information on the reproductive biology of horsegram for future hybridization program in order to enhance the performance of the crop and increase production. It also reveals differences in accessions from Benin compared with all other accessions from Mali, India or Australia.

Chasmogamy and entomophily in Burmannia disticha (Burmanniaceae).

Burmannia shows a set of floral traits that suggest elaborate mechanisms of animal-mediated pollen transfer. These include flower coloration, septal nectaries and a long and narrow floral chamber. The stamens are synorganized with the common style restricting the entrance to the floral chamber, sometimes forming a gynostegium. Contrary to this apparent zoophilous floral syndrome, several species of Burmannia were reported to perform self-pollination via cleistogamy. Understanding of reproductive systems in Burmannia is complicated by scarcity of available results of direct observations on pollination process. Here we present data on pollination biology of B. disticha obtained during field investigations in Vietnam followed by laboratory analyses of ecologically important floral traits and the captured flower visitors. We found that the anthetic perianth is open, i.e. the flower is chasmogamous. The flowers are visited by various Diptera, Hymenoptera, Lepidoptera and Orthoptera. Of them, the bumblebees (Bombus burmensis), a bee (Coelioxys sp.) and some lepidopterans were revealed to carry pollen of B. disticha. Based on the amount of carried pollen, insect behavior during the visits and general knowledge on biology of these insect taxa, we concluded that the bumblebees act as the principal pollinators of B. disticha, whereas the lepidopterans are considered as its possible pollinators. We compared the lengths of proboscises of the captured insects to the depth of the floral chamber, and found that only the bumblebees and lepidopterans should be able to reach the nectar. Finally, we estimated the pollen-ovule ratio of B. disticha as 6.84, which is comparable to the ratio known in autogamous angiosperms. Based on its flower organization and pollination mechanism, we consider B. disticha an entomophilous and predominantly xenogamous species. Its gynostegium is likely an adaptation for pollen transfer by insects with long proboscises. At the same time, earlier investigations together with pollen-ovule ratio indicate that B. disticha possesses a labile pollination strategy, and autogamy sometimes occurs. Since Burmannia is one of the few angiosperm genera that comprise both mycoheterotrophic (achlorophyllous) and autotrophic (green) species, our study provides important evidence for reconstructions of ecological and morphological evolutionary pathways in relation to the mode of organic nutrition.

Updated Species Check-list of the Indonesian Stingless Bees (Hymenoptera, Apidae, Apinae, Meliponini)

A catalog provides an index to previous studies in taxonomy, behavioral research, and pollination ecology, thus consolidating the existing knowledge in an accessible format. In this study, we explore the annotated catalog and bibliography of the Indonesian meliponini stingless bees (Hymenoptera, Apidae, Apinae, Meliponini). The catalog format is arranged based on Rasmussen (2008). All available literature was reviewed for compiling this catalog and bibliography. References to a Meliponini genus only were not included in the list of references. Cited references must have used a trackable specific epithet to have been included. In total, Indonesia has 52 recorded stingless bee species across the Indonesian archipelagoes of Sumatera (27 species), Java (13 species), Nusa Tenggara (1 species), Kalimantan (34 species), Sulawesi (8 species), Bali (1 species), Maluku (4 species), and Papua (12 species). After the data was updated, there was an increase in the number of stingless bee species in Indonesia, namely 46 species (before update) to 52 species (after update). An up-to-date, comprehensive taxonomic and biological catalog is fundamental to any comparative evolutionary, ecological, and behavioral research on any group of organisms.

Floral hairs of Tradescantia fluminensis (Commelinaceae) manipulate behavior of hoverflies for effective pollination

AbstractHairs often form on the flowers of Commelinaceae plants; however, their role in pollination ecology remains unclear. I examined the hypothesis that the dense hairs on the floral filaments of Tradescantia fluminensis (Commelinaceae) induce prolonged walking of pollinators on the petals, thus promoting effective pollination. This was done by comparing the behavior of flower‐visiting hoverflies on hair‐trimmed and control flowers. Hoverflies, the main pollinators of T. fluminensis, exhibited proboscis extension behavior towards hairs on floral filaments. Structural equation modeling analysis showed that the floral hairs increased the number of times the hoverflies touched the stamens, owing to the longer time that the hoverflies walked on the petals. These results suggest that the floral hairs of T. fluminensis mimic stamens, thereby enhancing pollination efficiency.

Pollination and floral insect visitors of non-native Crataegus monogyna Jacq and Crataegus mexicana DC (Rosaceae) in the Eastern Cape Province, South Africa

Crataegus species (Rosaceae) or hawthorns form dense thickets and displace native vegetation out of their native range. In South Africa, Crataegus monogyna and C. mexicana are under surveillance but there is lack of information on their pollination ecology. Therefore, this study sought to investigate the pollination mechanism and potential insect pollinators of these plants. Pollinator exclusion experiments were conducted on ten plants each of C. monogyna and C. mexicana near the towns of Hogsback and Seymour respectively, in the Eastern Cape Province. Flowers of each of these species were also observed to determine the diversity and distribution of insect visitors throughout the day (i.e. morning, mid day and afternoon). The results showed that C. monogyna and C. mexicana are capable of self and cross-pollination. Fruit set from open inflorescences of C. monogyna was 40.88 ± 0.08%, significantly higher than bagged inflorences. Fruit set from open inflorescences of C. mexicana was 48.18 ± 0.03%, significantly higher than those of bagged inflorescences. Hymenopterans were the most frequent visitors on C. monogyna flowers while dipterans were the most frequent visitors on C. mexicana flowers. The distribution of insects did not vary with the time of day for each plant species. Insect pollination, therefore, plays a significant role in the fruiting of C. monogyna and C. mexicana in the Eastern Cape. The results of this study contribute to the understanding of the ecology and phenology of Crataegus species in South Africa and thus the evaluation of their invasive status.

Pollinator competition and the structure of floral resources

The mutualism between plants and pollinators is built upon the trophic ecology of flowers and florivores. Yet the ecology of flowers‐as‐food is left implicit in most studies of plant–pollinator ecology, and it has been largely neglected in mainstream trophic ecology. This deficit is especially evident in an emerging issue of basic and applied significance: competition between pollinators for floral resources. In this synthesis, we start by exploring the notion of floral resource limitation upon which most studies concerning competition between pollinators are tacitly predicated. Both theoretical and empirical lines of evidence indicate that floral resource limitation must be understood as a complex ecological contingency; the question is not simply whether but when, where and in what regions of floral trait space resources are limiting. Based on this premise, we propose a framework for understanding floral resource availability in terms of temporal, spatial and functional structure. While this framework is conceptually intuitive, it is empirically and analytically demanding. We review existing methods for measuring and summarizing the multi‐dimensional structure of floral resources, highlight their strengths and weaknesses, and identify opportunities for future methods development. We then discuss the causal relationships linking floral resource structure to species coexistence, plant–pollinator community dynamics, and exogenous drivers like climate, land use, and episodic disturbances. In its role as both cause and effect, floral resource structure mediates the relationship between behavioral ecology, landscape ecology, and coexistence theory with respect to flowers and florivores. Establishing floral resource structure as an object of study and application will both shed light on basic questions of coexistence and guide management decisions concerning contentious issues such as the compatibility of apiculture with wild pollinator conservation and the appropriate use of floral enhancements in agri‐environment schemes.

Pollination ecology of an important medicinal plant Hellenia speciosa (J.Koenig) S.R.Dutta of Asiatic tropics

Abstract. Samanta A, Bera B, Karmakar P. 2023. Pollination ecology of an important medicinal plant Hellenia speciosa (J.Koenig) S.R.Dutta of Asiatic tropics. Biodiversitas 24: 3152-3161. Plants often show various floral traits that help them to achieve reproductive fitness. Floral adaptive traits help to maximize the possibility of outcrossing, even for clonally propagated plants. Furthermore, seed setting through successful pollination increases genetic diversity in clonal populations. This present study aimed to describe the flowering phenology, flower biology, pollinators, and breeding system of Hellenia speciosa, a perennial herb with rhizomes from the Costaceae family. According to our study, a pollen-ovule ratio of 210:1 indicates that the plant tends to facultative autogamy; however, the plant exhibits traits such as a large landing labellum for pollinators, bilabiate floral architecture, nototribic blossoms, a prominent nectar guide, abundant floral nectar (27.64±2.661 µL/flower), and high seed set through xenogamy (68.6± 3.07 standard error) to improve reproductive success through outcrossing. Here, the plant is pollinated by two hymenopteran members, namely Xylocopa auripennis and Amegilla zonata. Despite its ample nectar production, the plant is hardly visited by any honey bee species. GCMS analysis of floral nectar found 2-hexanol and derivatives of xylose were probably responsible for pollinator specificity and honey bee exclusion events, respectively.

Deciphering the ecology of the threatened microendemic species Euphorbia margalidiana.

Small islands play a critical role in the study of plant ecology and evolution. Here, we reveal the ecology of Euphorbia margalidiana, an endemic plant that thrives in a micro-island environment in the Western Mediterranean region. Through a detailed characterization of the habitat, including plant communities, microclimate, soil properties, and germination assays, we examine the effects of biotic and abiotic factors on the distribution of this endangered species. We also analyze its pollination biology, evaluate the success of vegetative propagation, and discuss its potential use in conservation strategies. Our results show that E. margalidiana is a characteristic species of the shrub ornitocoprophilous insular vegetation of the Western Mediterranean. The seeds have a very low dispersion capacity outside the islet and that seed-derived plants have higher survival rates under drought conditions than those vegetatively propagated. The main volatile compound emitted from the pseudanthia is phenol which attracts the plants' main and almost exclusive pollinators in the islet, flies. Our results confirm the relictual status of E. margalidiana and highlight the importance of key adaptive traits that enable the survival of this species in the harsh micro-island environment of Ses Margalides.

The Family Megachilidae (Hymenoptera: Apoidea) In Pollination Ecology- a Review

Family Megachilidae belongs to cosmopolitan family groups, making nests in the soil, and mostly prefer pre-existing cavities such as pithy stems, galls, and dead wood for nesting. Mostly they are solitary, long-tongued, and have pollen-collecting structure scopa present on the ventral side of the abdomen rather than hind legs (mostly in other bees). Genus Megachilid is generally known as leaf cutter and mason bees. Family Megachilidae is characterized by different groups of the bees such as solitary, mason, resin, carder, and leafcutter bees, and are the most important pollinators for agricultural, horticultural, medicinal, and aromatic plants. Female leafcutter bees have a special character to form brood cells by using their mandibles to cut leaves. Family Megachilidae is found throughout the world except for Antarctica, lowland tropical rain forests, deserts, and hilly ecosystems, and 238 species are listed from the Indian region. Our review is based on the significant role of the family Megachilidae and their different adaptive structures and behaviour to enhance their contribution to the pollination ecology.

Pollination Biology in Henna Evidences from Semi-Arid Region of Rajasthan

Pollination Biology in Henna Evidences from Semi-Arid Region of Rajasthan

Ants are more than just curious bystanders to some flowers-they act as significant pollinators.

Ant-plant associations are ubiquitous and highly diverse in almost all terrestrial environments, resulting in complex ecological networks. Although ant-plant mutualism is prevalent, ant-mediated pollination is uncommon, and only a few investigations have demonstrated their role in pollination. Thus, the topic of ant-mediated pollination requires revision to assess its significance in pollination biology. Ants are frequent floral visitors, but their impact on plant reproductive fitness is rarely acknowledged; nonetheless, numerous flower-visiting ants have been investigated for their involvement in promoting floral development and hybrid vigor in crops. In this study, we present a summary of the scientific literature published over the last four decades on ants' involvement in pollination, the diversity of pollinating ants to various host plants, the ant-plant pollinating networks, and seasonal patterns of ant-mediated pollination. Ants generally forage for flowers in quest of nectar and other sustenance, and in doing so they pollinate the flowers that they encounter. This review identified the pollination networks between ants and plants at the species and family levels. Pollination is often affected by a number of aspects, including the flower's sex, its ovary position, the inflorescence it bears, and the time of year. The available literature demonstrates that ants visit the inflorescences of the same species only to promote cross-pollination, a process known as "geitonogamy"; however, we conclude that ants may visit different inflorescences of different plants in the field. If ant pollination is the norm, there is less selection pressure to acquire self-compatibility; nonetheless, ants' cross-pollination may have caused ants to co-evolve with the pollinating flowers. This indicates that ants are more than just curious bystanders to some flowers; they act as significant pollinators.

The floral biology and the role of staminal connective appendages during pollination of the endoparasite Bdallophytum americanum (Cytinaceae).

Bdallophytum americanum (Cytinaceae) is an endoparasitic plant species, meaning only the flowers emerge from the host during the reproductive season. Reports on the pollination biology of this species state that its primary pollinators are carrion flies attracted by the smell of the flowers and nectar as a reward. However, the functional role of one of the most outstanding attributes of B. americanum has been neglected. These are the staminal appendages formed by the apical overgrowth of connective tissue during anther development. To determine whether these staminal appendages play a role in pollination, we monitored a nectarless population of B. americanum. We described the inflorescence emergence, floral movements, and pollination and performed field experiments to test whether the absence of the staminal connective appendages affected the visitation frequency. Male inflorescences emerge early, and both male and female flowers open during the day and do not close. Hoverflies are the most frequent visitors to both floral sexes and carry the most pollen. Moreover, the movement of staminal appendages matching the pollen viability changes is reported for the first time. The staminal appendages are the structures where pollinators land before foraging. The field experiments showed that the visitation frequency decreased sharply without staminal appendages. As a landing platform, the staminal connective appendages in B. americanum are crucial for pollinator positioning and collecting viable pollen.

Genetic Mechanisms for Hybrid Breeding in Vegetable Crops.

To address the complex challenges faced by our planet such as rapidly changing climate patterns, food and nutritional insecurities, and the escalating world population, the development of hybrid vegetable crops is imperative. Vegetable hybrids could effectively mitigate the above-mentioned fundamental challenges in numerous countries. Utilizing genetic mechanisms to create hybrids not only reduces costs but also holds significant practical implications, particularly in streamlining hybrid seed production. These mechanisms encompass self-incompatibility (SI), male sterility, and gynoecism. The present comprehensive review is primarily focused on the elucidation of fundamental processes associated with floral characteristics, the genetic regulation of floral traits, pollen biology, and development. Specific attention is given to the mechanisms for masculinizing and feminizing cucurbits to facilitate hybrid seed production as well as the hybridization approaches used in the biofortification of vegetable crops. Furthermore, this review provides valuable insights into recent biotechnological advancements and their future utilization for developing the genetic systems of major vegetable crops.

Decoding the black essence of Melianthus nectar.

This article is a Commentary on Magner et al. (2023), 239: 2026–2040.

Pollination biology of yellow passion fruit (Passiflora edulis forma flavicarpa) at typical Indonesian small-scale farming

Abstract. Putra RE, Wibisana G, Kinasih I, Raffiudin R, Soesilohadi RCH, Purnobasuki H. 2023. Pollination biology of yellow passion fruit (Passiflora edulis forma flavicarpa) at typical Indonesian small-scale farming. Biodiversitas 24: 2179-2188. Yellow passion fruit (Passiflora edulis forma flavicarpa) has been considered one of the potential local fruits targeted as the export commodity of Indonesia. However, this fruit production level is relatively unstable, which lowers their potency as cash crops and makes them secondary fruits for small-scale farmers. One of the possible factors related to this condition is pollination success. This research aimed to study the pollination biology of yellow passion fruit in terms of flower interaction with insects and the morphological aspect of flowers. The observation was conducted in four sites at Kampung Organik Beji, Wonogiri Regency, between January-February 2022. Pollinators' census was done by scan sampling while flower-visiting insect activities were monitored by focal sampling. This study found 26 species of flower-visiting insects which can be grouped into 5 Ordo and 12 Families with moderate diversity index (H’=2.15), evenly distributed (J’=0.66), and low domination (D=0.32). Among identified insects, carpenter bees (Xylocopa latipes), stingless bees (Tetragonula laeviceps), and Asiatic honey bees (Apis cerana) were considered as pollinators in which X. latipes (Vt=11.81±7.44 second, Fvr=2.41±1.55) visited flower (Vt) on shorter times, and more flower visitation rate (Fvr) than T. laeviceps (Vt=12.36±8.32 second, Fvr=1.10±0.30). Furthermore, this study found that the benefit of natural pollination was better than hand cross-pollination. However, the benefit was hampered by a lack of plant protection and soil fertility management. This study may be applied as baseline information to create pollinator protection zones in the area near the plantation zone to ensure the pollination services for crops.

Floral scent and pollination of the invasive plant Coreopsis lanceolata in Japan

The invasive plant Coreopsis lanceolata threatens ecosystems in Japan by competing for resources with native plants. This species is self-incompatible and requires pollinator agents for seed production; however, it is known to produce many seeds. Here, we document the pollination biology and plant-pollinator interactions that facilitate seed production of C. lanceolata in the introduced range. Results revealed that C. lanceolata attracted a wide array of floral visitors comprising 60 species from 20 families. Although most floral visitors could be potential pollinators, the functional groups of halictid bees appeared to be the most important pollinators of C. lanceolata in terms of visitation frequency and the ability to carry pollen. The floral scent emission of C. lanceolata consists predominantly of monoterpenes, sesquiterpenes, and benzenoids. Furthermore, the mean seed set was nearly 30% of the ovule mean. Our study confirmed that in the introduced range in Japan, C. lanceolata is integrated into the local pollinator community, especially with the functional group of halictid bees involved in the reproductive success.

Characterizing each step of pollination in Phlox drummondii reveals a single butterfly species predominates the pollinator assemblage.

A central goal of pollination biology is to connect plants with the identity of their pollinator(s). While predictions based on floral syndrome traits are extremely useful, direct observation can reveal further details of a species' pollination biology. The wildflower, Phlox drummondii, has a floral syndrome consistent with Lepidoptera pollination. We test this prediction using empirical data. We observe each step of pollination in P. drummondii. First, we observe 55.5 hours of floral visitation across the species range. We use temporal pollinator exclusion to determine the contribution of diurnal and nocturnal pollination to reproductive output. We then quantify P. drummondii pollen transfer by the dominant floral visitor, Battus philenor. Finally, we test the effect of B. philenor visitation on P. drummondii reproduction by quantifying fruit set following single pollinator visits. B. philenor is the primary pollinator of P. drummondii. Pollination is largely diurnal, and we observe a variety of lepidopteran visitors during this period. However, B. philenor is the most frequent visitor, representing 88.5% of all observed visits. We show that B. philenor is an extremely common visitor and also an effective pollinator by demonstrating that individuals transfer pollen between flowers and that a single visit can elicit fruit set. Our data are consistent with the prediction of lepidopteran pollination and further reveal a single butterfly species, B. philenor, as the primary pollinator. Our study demonstrates the importance of empirical pollinator observations, adds to our understanding of pollination mechanics, and offers a specific case study of butterfly pollination. This article is protected by copyright. All rights reserved.

Understanding reproductive biology for realization of conservation and sustainable development of Swertia thomsonii C. B. Clarke-an endemic medicinal plant of Western Himalaya

Swertia thomsonii an important medicinal plant of Himalaya is more susceptible to extinction in the scenario of anthropogenic threats and global climate change. Therefore a detailed study on reproductive biology was undertaken for its conservation and sustainable use. The present study was conducted with the aim to understand reproductive strategies, breeding behaviour and pollination ecology of this prized, endemic medicinal plant species. It is a perennial rhizomatous herb growing along an altitudinal gradient of 2550–3400 m a.s.l. The flowering commences from the month of August and continuous till September. The variation in floral traits was observed across the altitudinal gradients, which reflects its phenotypic plasticity in these characters that helps the species to get adapted in different environmental conditions. The pollen viability recorded in three study sites viz. Gulmarg (SS-I), Doodhpathri (SS-II), Pahalgam (SS-III) was 89.83 ± 3.1, 75.86 ± 5 and 84.5 ± 2.5% respectively. Stigma becomes receptive 4–5 days after anthesis and reaches its peak on 6–7th day. The presence of typical floral characteristics such as asynchronous anthesis, conspicuous nectaries, spiny exine of pollen, dichogamy, and herkogamy points towards entomophilous and outcrossing nature. Reproductive indices like outcrossing index (OCI), self-incompatibility index (SI) and selfing rate (S) as well as results of bagging experiments also revealed that the species is self as well as cross-compatible. However, fruit and seed set recorded in insect exclusion experiments confirmed its anemophilous nature and therefore species exhibits an ambophilous mode of pollination. Mixed matting is operative in the target plant species, preferring xenogamy followed by geitonogamy and autogamy. The species is pollinated by specialized pollinators which mostly belong to the Order Hymenoptera. Suitable media for in-vitro pollen germination has also been identified; the knowledge about peak stigma receptivity and pollen germination is indispensable for breeding programmes. Thus the scientific information generated in the present study may prove useful in different breeding programmes and conservation of this valuable plant species.

Developing and Evaluating a New Method and Apparatus for Examining Bumble Bee Foraging Behavior

A key question in pollination biology is that of how pollinators identify and choose foraging patches. Several approaches have been employed for this, including field studies and large greenhouse flight chambers. Most methods used to date are limited, though, by reliance on a combination of artificial flowers, large spatial scales, or lack of spatially distinct floral patches. To address this issue, we designed and tested a y-maze flight arena and tested it using the bumblebee Bombus impatiens and canola plants. Our results indicate that the system is not biased by environmental conditions, or by an innate “handedness” of Bombus impatiens. We found that bees made all the expected patch choices when presented with soil, plants without flowers, or plants with flowers. This new method is important and useful as it allows researchers to ask questions of both plant health and insect behavior and the chamber system is modular allowing for simple changes to the setup to focus on different questions. • Y-maze flight arena was designed to evaluate foraging behavior on intact plants. • No evidence of side preference in individual bees. • Behaviors observed in the y-maze appear to correspond to behaviors observed in other settings.