Preference For Flowers Research Articles

Biomechanics of nectar feeding explain flower orientation in plants pollinated by long-proboscid flies.

The function of flower orientation is much debated, with adaptation to pollinator mouthparts being a particularly compelling explanation, but also one that has lacked empirical support from broad-scale comparative studies. The two families of long-proboscid fly pollinators show similar hovering behaviour while feeding on nectar but differ in the biomechanics of their proboscides which can be up to 80mm in length: Tabanidae have a fixed forward-pointing proboscis while Nemestrinidae can swivel their proboscis downwards. We predicted that this difference has implications for the evolution of flower orientation. We established the flower angles of 156 South African plant species specialised for pollination by long-proboscid flies. Using a phylogenetically corrected analysis, we found that flowers pollinated by Tabanidae tend to be horizontally orientated, while those pollinated by Nemestrinidae tend to be more variable in orientation and more often vertically orientated. These results confirm the importance of pollinator biomechanics for the evolution of floral traits and highlight a potential mechanism of reproductive isolation between sympatric plant species pollinated by different long-proboscid fly families.

Identification of the operating position and orientation of a robotic kiwifruit pollinator

Accurate identification of flower position and orientation is an essential prerequisite for robotic pollinators to accomplish precise targeted pollination and improve the pollen utilisation rate. To accurately identify the pollination position and orientation of kiwifruit flowers, this study presents a vision-based information perception approach for automatically detecting flowers and accurately identifying their positions and orientations. After using YOLO v4 to identify the kiwifruit flower, the contour detection algorithm was used to detect the contour boundary of the flower pistil area and the contour boundary of the minimum circumscribed circle of the petals, and fit the centres of gravity of the pistil contour and the petal contour according to the two contours respectively. The line connecting the two centre points was used as the central axis representing the growth direction of the flowers, achieving precise identification of the flower position and orientation. After building a robotic pollinator, an experiment was conducted to identify kiwifruit flower targets and a performance test experiment was performed to target pollinated kiwifruit flowers in a kiwifruit orchard with a mechanical arm based on flower position and orientation. The experimental results showed that the precision of the identification of kiwifruit flowers was 95.27%, the success rate of the mechanical arm for target pollination based on flower position and orientation identification was 89.59%, the average pollination time was 6 s⋅per flower, and the pollination efficiency was 20 h⋅ha-1. The identification algorithm of flower position and orientation proposed in this study can improve the precision and success rate of robotic pollination.

Insect Floral Visitors of Ptelea trifoliata (Rutaceae) in Iowa, United States.

Ptelea trifoliata L., is a North American tree that supports insect communities through floral rewards. Our objectives were to determine the importance of insects as pollinators of P. trifoliata; describe the community of floral visiting insects of P. trifoliata in Iowa, where no such information was available; and to note insect preferences for male or female flowers. Over two years, inflorescences on 13 trees were covered with mesh bags before blooming and the amount of fruit produced was compared to uncovered inflorescences from the same trees. In one year, insects were collected from male and female trees with an insect vacuum every 3 h between 7 am and 7 pm from four sites in Iowa, USA between 30 May and 16 June 2020. In 2019 and 2020, almost no fruit set occurred from inflorescences covered with mesh bags while an average of 51.2 fruits formed on unbagged inflorescences (P < 0.0001), suggesting insects larger than the 600 μm pore diameters mesh were responsible for pollination of P. trifoliata. Insects from five orders, 49 families, and at least 109 species were collected. Most insects were Hymentoptera (48.3%) or Diptera (28.2%). Male flowers attracted 62.3% of all insects collected. Since most of the insects found visiting P. trifoliata were not bees, the floral rewards of the flowers may be a valuable resource for a wide variety of insects in the central United States.

Horizontal orientation facilitates pollen transfer and rain damage avoidance in actinomorphic flowers of Platycodon grandiflorus.

In zoophilous plants, floral orientation evolved under both biotic and abiotic pressure to enhance pollination success. However, the adaptive significance of horizontal orientation in radially symmetrical (actinomorphic) flowers remains largely unknown, although that of bilaterally symmetrical flowers has been well studied. We experimentally altered floral angle in a population of insect-pollinated Platycodon grandiflorus flowers to examine the effects of floral orientation on pollinator behaviour, pollination success and pollen rain damage avoidance. To further investigate the potential pollen damage by rain, we obtained past precipitation records for the study area during the flowering season, and experimentally tested P. grandiflorus pollen damage by water. Horizontally oriented flowers received more pollinator visits and had pollen grains on the stigma in male and/or female phases than downward- and/or upward-oriented flowers and avoided pollen damage by rainfall better than upward-oriented flowers. A pollen germination experiment showed that approximately 30% of pollen grains burst in distilled water, indicating that pollen damage by rainfall may be significant in P. grandiflorus. Our field experiments revealed that upward-oriented flowers cannot avoid pollen damage by rainfall during the flowering period, and that both upward- and downward-oriented flowers experience pollinator limitation in female success. Therefore, horizontal flower orientation appears to be adaptive in this insect-pollinated actinomorphic species that blooms during the rainy season.

Citizen science reveals current distribution, predicted habitat suitability and resource requirements of the introduced African Carder Bee Pseudoanthidium (Immanthidium) repetitum in Australia

The introduction of non-native bee species is a major driver of ecosystem change resulting in the spread of non-native weeds, alterations to plant-pollinator interactions and competition with native species for food and nesting resources. Our lack of ecological information for many non-native organisms hinders our ability to understand the impacts of species introductions. This is often compounded by the Wallacean Shortfall—a lack of adequate knowledge of a species’ distribution in geographic space. In Australia, the African carder bee (Pseudoanthidium (Immanthidium) repetitum) was first observed in 2000 and has since become one of the most common bees in some regions. Despite its rapid population increase and range expansion, little is known about the ecology or distribution of P. repetitum. In this study, we determine the flower preferences, current distribution and predicted areas at risk of future invasion of P. repetitum using opportunistic data collected from citizen science websites, social media and museum records. We found that the current distribution of P. repetitum in Australia encompasses approximately 332,000 km2 concentrated along the eastern coast. We found considerable suitable habitat outside the current distribution including biodiversity hotspots and world heritage listed natural areas. Pseudoanthidium repetitum foraged on a wide range of plants from many families and can thus be classified as a generalist forager (polylectic). Our results suggest that P. repetitum is well suited for continued expansion in coastal Australia. Our results demonstrate the effective application of opportunistic data in overcoming knowledge gaps in species ecology and modelling of introduced species distribution.

The role of adult noctuid moths (Lepidoptera: Noctuidae) and their food plants in a nocturnal pollen-transport network on a Mediterranean island

Noctuidae belong to one of the largest families of night-flying Lepidoptera. However, despite being among the most common nocturnal flower-visitors, they have seldom been included in pollination networks. Similarly, the current knowledge on food plants used by adults is rather scarce. In this article, we build the first moth–plant pollen transfer network in the Balearic archipelago. We aim to increase the knowledge of which plants are used as food resources by adult Noctuidae, assess how specific or generalist nocturnal pollinators and their food plants are and establish the first baseline information on adult Noctuidae–plant interactions on the archipelago and the Mediterranean. 20.7% of the adult Noctuidae in our samplings carried pollen and were therefore potentially involved in nocturnal pollination. The family Ericaceae, and especially Arbutus unedo, was a key food resource for our moth community, with 46% of the total recorded interactions belonging to this plant. Overall, both plants and moths in our system behaved in a generalist way. Niche overlap was larger in moths than in plants, suggesting that the functional role that moth species take in our system is more redundant than that taken by plants. Robustness values suggest that the network functionality would not collapse despite the extinction of a few species.Implications for insect conservationDetecting flower preferences and the role of nocturnal insects on pollination will allow understanding of ecosystem functionality and will be crucial for conservation of both moths and organisms that depend on them.

Study on selection of native greening plants based on eye-tracking technology

The selection of native greening plants to improve rural greening technology is crucial for enriching methods of building rural plant landscapes. However, there are few studies from the perspective of visual preference using quantitative methods. By using eye-tracking technology, this study studies students in the Central South University of Forestry and Technology and villagers in Changkou Village, Fujian Province, employing pictures of plant organs—leaves, flowers, and fruits—as stimulating materials to analyze five indicators: the total duration of fixations, the number of fixations, average duration of fixations, average pupil size and average amplitude of saccades. A number of findings came from this research First, people visually prefer leaves, followed by flowers and fruits. In terms of species, Photinia × fraseri, Metasequoia glyptostroboides, Photinia serratifolia, Cunninghamia lanceolata and Koelreuteria bipinnata have higher overall preference. Families such as Malvaceae, Fabaceae, Araliaceae, Myricaceae and Cupressaceae have stronger visual attraction than others. Second, there are distinct differences in the preference of shapes and textures of leaves: aciculiform, strip, cordiform, sector and jacket-shape are more attractive; leather-like leaves have a higher visual preference than paper-like leaves; different colors and whether leaves are cracked or not have little effect on leaf observation. Third, the preference for flowers with different inflorescence and colors is significant. Capitulum, cymes and panicles are more attractive; purple is the most preferred color, followed by white, yellow and red. Finally, there are significant differences in preferences for fruit characteristics, with medium-sized fruits and black fruits preferred, while kidney-shaped and spoon-shaped fruits are considered more attractive. Pomes, pods, samaras, and berries have received relatively more attention.

The emergence of collective knowledge and cumulative culture in animals, humans and machines.

The emergence of collective knowledge and cumulative culture in animals, humans and machines.

Innate and learnt color preferences in the common green-eyed white butterfly (Leptophobia aripa): experimental evidence.

BackgroundLearning abilities help animals modify their behaviors based on experience and innate sensory biases to confront environmental unpredictability. In a food acquisition context, the ability to detect, learn, and switch is fundamental in a wide range of insect species facing the ever-changing availability of their floral rewards. Here, we used an experimental approach to address the innate color preferences and learning abilities of the common green-eyed white butterfly (Leptophobia aripa).MethodsIn Experiment 1, we conducted innate preference choice-tests to determine whether butterflies had a strong innate color preference and to evaluate whether color preferences differed depending on the array of colors offered. We faced naïve butterflies to artificial flowers of four colors (quadruple choice-test): yellow, pink, white, and red; their choices were assessed. In Experiment 2, we examined the ability of this butterfly species to associate colors with rewards while exploring if the spectral reflectance value of a flower color can slow or accelerate this behavioral response. Butterflies were first trained to be fed from artificial yellow flowers inserted in a feeder. These were later replaced by artificial flowers with a similar (blue) or very different (white) spectral reflectance range. Each preference test comprised a dual-choice test (yellow vs blue, yellow vs white).ResultsButterflies showed an innate strong preference for red flowers. Both the number of visits and the time spent probing these flowers were much greater than the pink, white, and yellow color flowers. Butterflies learn to associate colors with sugar rewards. They then learned the newly rewarded colors as quickly and proficiently as if the previously rewarded color was similar in spectral reflectance value; the opposite occurs if the newly rewarded color is very different than the previously rewarded color.ConclusionsOur findings suggest that common green-eyed white butterflies have good learning abilities. These capabilities may allow them to respond rapidly to different color stimulus.

Spontaneous choices for insect-pollinated flower shapes by wild non-eusocial halictid bees.

The majority of angiosperms require animal pollination for reproduction, and insects are the dominant group of animal pollinators. Bees are considered one of the most important and abundant insect pollinators. Research into bee behaviour and foraging decisions has typically centred on managed eusocial bee species, including Apis mellifera and Bombus terrestris. Non-eusocial bees are understudied with respect to foraging strategies and decision making, such as flower preferences. Understanding whether there are fundamental foraging strategies and preferences that are features of insect groups can provide key insights into the evolution of flower-pollinator co-evolution. In the current study, Lasioglossum (Chilalictus) lanarium and Lasioglossum (Parasphecodes) sp., two native Australian generalist halictid bees, were tested for flower shape preferences between native insect-pollinated and bird-pollinated flowers. Each bee was presented with achromatic images of either insect-pollinated or bird-pollinated flowers in a circular arena. Both native bee species demonstrated a significant preference for images of insect-pollinated flowers. These preferences are similar to those found in A. mellifera, suggesting that flower shape preference may be a deep-rooted evolutionary occurrence within bees. With growing interest in the sensory capabilities of non-eusocial bees as alternative pollinators, the current study also provides a valuable framework for further behavioural testing of such species.

Flower orientation influences floral temperature, pollinator visits and plant fitness.

Effective insect pollination requires appropriate responses to internal and external environmental cues in both the plant and the pollinator. Helianthus annuus, a highly outcrossing species, is marked for its uniform eastward orientation of mature pseudanthia, or capitula. Here we investigate how this orientation affects floral microclimate and the consequent effects on plant and pollinator interactions and reproductive fitness. We artificially manipulated sunflower capitulum orientation and temperature in both field and controlled conditions and assessed flower physiology, pollinator visits, seed traits and siring success. East-facing capitula were found to have earlier style elongation, pollen presentation and pollinator visits compared with capitula manipulated to face west. East-facing capitula also sired more offspring than west-facing capitula and under some conditions produced heavier and better-filled seeds. Local ambient temperature change on the capitulum was found to be a key factor regulating the timing of style elongation, pollen emergence and pollinator visits. These results indicate that eastward capitulum orientation helps to control daily rhythms in floral temperature, with direct consequences on the timing of style elongation and pollen emergence, pollinator visitation, and plant fitness.

Bumble bees show an induced preference for flowers when primed with caffeinated nectar and a target floral odor

Caffeine is a widely occurring plant defense chemical1,2 that occurs in the nectar of some plants, e.g., Coffea or Citrus spp., where it may influence pollinator behavior to enhance pollination.3,4 Honey bees fed caffeine form longer lasting olfactory memory associations,5 which could give plants with caffeinated nectar an adaptive advantage by inducing more visits to flowers. Caffeinated free-flying bees show enhanced learning performance6 and are more likely to revisit a caffeinated target feeder or artificial flower,7-9 although it is not clear whether improved memory of the target cues or the perception of caffeine as a reward is the cause. Here, we show that inexperienced bumble bees (Bombus terrestris) locate new food sources emitting a learned floral odor more consistently if they have been fed caffeine. In laboratory arena tests, we fed bees a caffeinated food alongside a floral odor blend (priming) and then used robotic experimental flowers10 to disentangle the effects of caffeine improving memory for learned food-associated cues versus caffeine as a reward. Inexperienced bees primed with caffeine made more initial visits to target robotic flowers emitting the target odor compared to control bees or those primed with odor alone. Caffeine-primed bees tended to improve their floral handling time faster. Although the effects of caffeine were short lived, we show that food-locating behaviors in free-flying bumble bees can be enhanced by caffeine provided in the nest. Consequently, there is potential to redesign commercial colonies to enhance bees' forage focus or even bias bees to forage on a specific crop.

Bumblebees can detect floral humidity.

ABSTRACTFloral humidity, a region of elevated humidity in the headspace of the flower, occurs in many plant species and may add to their multimodal floral displays. So far, the ability to detect and respond to floral humidity cues has been only established for hawkmoths when they locate and extract nectar while hovering in front of some moth-pollinated flowers. To test whether floral humidity can be used by other more widespread generalist pollinators, we designed artificial flowers that presented biologically relevant levels of humidity similar to those shown by flowering plants. Bumblebees showed a spontaneous preference for flowers that produced higher floral humidity. Furthermore, learning experiments showed that bumblebees are able to use differences in floral humidity to distinguish between rewarding and non-rewarding flowers. Our results indicate that bumblebees are sensitive to different levels of floral humidity. In this way floral humidity can add to the information provided by flowers and could impact pollinator behaviour more significantly than previously thought.

Older adults’ domestic green environments: the preference for flowers

ABSTRACT Greenspaces and access to nature are widely accepted as being beneficial to older adult’s health and well-being. Less well known are the natural elements in their domestic outdoor environments that are used and preferred. In this paper, we identify those most preferred by 72 older adults in New Zealand living in family homes, downsized homes and rest homes. Through the use of geographic information system mapping and photos, we assessed how these individual elements relate to residence type, age, frailty and intrinsic interest in nature. The type of residence and innate nature relatedness were strongly reflected in the items selected by participants. The elements most frequently reported across all residence types were primarily non-native flowers/flowering shrubs and trees, sitting places, views, birds, vegetables, fruit and herbs. The findings have implications for landscape garden design and plant selection but also present a challenge for encouraging more native species in domestic environments.

An Optimized Transformation System and Functional Test of CYC-Like TCP Gene CpCYC in Chirita pumila (Gesneriaceae).

The development of an ideal model plant located at a key phylogenetic node is critically important to advance functional and regulatory studies of key regulatory genes in the evolutionary developmental (evo-devo) biology field. In this study, we selected Chirita pumila in the family Gesneriaceae, a basal group in Lamiales, as a model plant to optimize its genetic transformation system established previously by us through investigating a series of factors and further conduct functional test of the CYC-like floral symmetry gene CpCYC. By transforming a RNAi:CpCYC vector, we successfully achieved the desired phenotypes of upright actinomorphic flowers, which suggest that CpCYC actually determines the establishment of floral zygomorphy and the horizontal orientation of flowers in C. pumila. We also confirmed the activities of CpCYC promoter in dorsal petals, dorsal/lateral staminodes, as well as the pedicel by transferring a CpCYC promoter:GUS vector into C. pumila. Furthermore, we testified the availability of a transient gene expression system using C. pumila mesophyll protoplasts. The improved transformation system together with the inherent biological features would make C. pumila an attractive new model in functional and regulatory studies for a broad range of evo-devo issues.

Foraging Small White Butterflies, Pieris rapae, Search Flowers Using Color Vision

We demonstrate that the small white butterfly,Pieris rapae, uses color vision when searching flowers for foraging. We first trained newly emerged butterflies in a series of indoor behavioral experiments to take sucrose solution on paper disks, colored either blue, green, yellow, or red. After confirming that the butterflies were trained to visit a certain colored disk, we presented all disks simultaneously. The butterflies selected the disk of trained color, even among an array of disks with different shades of gray. We performed the training using monochromatic lights and measured the action spectrum of the feeding behavior to determine the targets’Pieris-subjective brightness. We used the subjective brightness information to evaluate the behavioral results and concluded thatPieris rapaebutterflies discriminate visual stimuli based on the chromatic content independent of the intensity: they have true color vision. We also found thatPierisbutterflies innately prefer blue and yellow disks, which appears to match with their flower preference in the field, at least in part.

Flowers morphology and nectar concentration determine the preferred food source of stingless bee, Heterotrigona itama

• Tongue length of H. itama is 2.30 ± 0.05 mm and can be extended to 3.39 ± 0.03 mm. • Averrhoa carambola produced the highest sugar nectar concentration (43.36 ± 2.55%). • Antigonon leptopus produced 34.40 ± 2.11% of nectar sugar concentration. • Both flowers have short tube length. It is compatible with the bee tongue length. • High sugar nectar and short tube length attract the bee to forage on both flowers. Heterotrigona itama is a stingless bee species from Meliponini tribe. The bee collects nectar, pollen and resin to produce honey, bee bread, and propolis. The bee is also known to visit and collect nectar from various types of flowers but there are limited studies on why this species of bee prefers to visit certain types of flowers. This study was conducted to identify the nectar concentration in selected flowers favoured by H. itama and the relationship between the bee and the morphology of the flowers. Nectar was obtained from different species of flowers and the concentrations were measured using a digital refractometer. The tube length of each flower species and the tongue length of the bees were also measured. The results revealed that flowers preferred by H. itama have high nectar concentrations. The tube lengths of the preferred flowers were between 2.0 and 4.0 mm, which is compatible with the tongue length of the bee. This study revealed that both nectar concentration and flower morphology are important factors for the bees in choosing their food sources. The results from this study will benefit the beekeepers in the identification of flowers that should be planted in their farms to improve stingless bee beekeeping activities. Understanding the relationship between the bees and their flower preferences could also help us to understand the importance of conserving both the bee colonies and the various species of flowering plants to ensure the sustainability of flora and fauna in the ecosystem.

Geographic Mosaics of Fly Pollinators With Divergent Color Preferences Drive Landscape-Scale Structuring of Flower Color in Daisy Communities.

The striking variation in flower color across and within Angiosperm species is often attributed to divergent selection resulting from geographic mosaics of pollinators with different color preferences. Despite the importance of pollinator mosaics in driving floral divergence, the distributions of pollinators and their color preferences are seldom quantified. The extensive mass-flowering displays of annual daisy species in Namaqualand, South Africa, are characterized by striking color convergence within communities, but also color turnover within species and genera across large geographic scales. We aimed to determine whether shifts between orange and white-flowered daisy communities are driven by the innate color preferences of different pollinators or by soil color, which can potentially affect the detectability of different colored flowers. Different bee-fly pollinators dominated in both community types so that largely non-overlapping pollinator distributions were strongly associated with different flower colors. Visual modeling demonstrated that orange and white-flowered species are distinguishable in fly vision, and choice experiments demonstrated strongly divergent color preferences. We found that the dominant pollinator in orange communities has a strong spontaneous preference for orange flowers, which was not altered by conditioning. Similarly, the dominant pollinator in white communities exhibited an innate preference for white flowers. Although detectability of white flowers varied across soil types, background contrast did not alter color preferences. These findings demonstrate that landscape-level flower color turnover across Namaqua daisy communities is likely shaped by a strong qualitative geographic mosaic of bee-fly pollinators with divergent color preferences. This is an unexpected result given the classically generalist pollination phenotype of daisies. However, because of the dominance of single fly pollinator species within communities, and the virtual absence of bees as pollinators, we suggest that Namaqua daisies function as pollination specialists despite their generalist phenotypes, thus facilitating differentiation of flower color by pollinator shifts across the fly pollinator mosaic.

A half-day flowering pattern helps plants sharing pollinators in an oceanic island community

AbstractThe temporal pattern of flower opening and closure is a feature of the biology of many plant species, particularly those inhabiting oceanic islands where flowering generally lasts for only a few hours per day. Additionally, flower visitors often seek different floral sources on a timely basis, thus the relative timing of interactions is central to their status in pollination competition, or in the facilitation of pollination among co-flowering plants sharing pollinators. However, few studies have examined the impacts of daily temporal variation in flowering patterns on the pollinator network and competition on a community scale. In order to examine whether the daily pattern of flower opening and closure can impose temporal dynamics on interspecific interactions within a single day, plant–pollinator interaction networks (AM subweb and PM subweb) were quantified, and the relevant interactions between the two subwebs were compared using the Bray–Curtis dissimilarity of visitation frequencies in an oceanic island community (Paracel Islands, South China Sea). The role of species within networks and its variation between two subwebs were assessed by calculating the species-level specialization and species strength of each plant and pollinator species. The quantitative plant–pollinator interaction dissimilarity between morning and afternoon subsets was 0.69, and this value dropped to 0.58 when considering plant species flowering throughout the day. In our study, this dissimilarity between the two subwebs might be explained by the morning peak activity rather than a preference for morning flowers. No significant differences were detected in the species-level specialization and species strength of plants flowering all day from morning to afternoon at the community level. The flower visitation rates of native honeybeeApis ceranawere not significantly different between morning and afternoon for most of the whole-day flowering plants. However, plant species only flowering either in the morning or the afternoon differed in the rate of visitation byA. cerana. The analyses of variation in the visitation rates of pollinators shared by plants within a single day in the studied community suggest that daily structuring at a community level and half-day staggered flowering during the morning or afternoon might reduce competitive interactions in oceanic insular habitats.

Horizontal orientation of zygomorphic flowers: significance for rain protection and pollen transfer.

Floral traits are recognized to have evolved under selection for abiotic and biotic factors. Complex zygomorphic flowers usually face horizontally. It has been proved that a horizontal orientation facilitates pollinator recognition and pollination efficiency, but its significance in adaptation to abiotic factors remains unknown. The floral orientation of Abelia×grandiflora naturally varies around horizontal (with an angle of -30 to +33° between the floral main axis and the horizontal). We examined whether three different floral orientations affected flower thermal conditions, response to rain and pollination. Results showed that floral orientation had no effect on diurnal variations in flower temperature. The anthers of all three flower orientations were wetted by rainfall, but the inclined upward-facing flowers contained significantly more rainwater. The horizontal flowers received significantly higher visitation by hawkmoths and had a higher stigmatic pollen load. In contrast, the upward flower orientation reduced pollination precision, while downward-facing flowers had decreased pollinator attraction. This study indicates that horizontal flowers may have evolved as a trade-off between rain protection and pollination. Zygomorphic flowers that deviate from a horizontal orientation may have lower fitness because of flower flooding by rainwater and decreased pollen transfer.