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Over a century of research on pollinator cognition has shown that pollinators such as bees perceive and learn a multitude of floral stimuli and are capable of sophisticated decision-making using a variety of cognitive abilities. Research on pollinator cognition usually focuses on a single reward aspect in isolation, which does not reflect the complexity of reward types, chemistries, and attributes many pollinators encounter while foraging. Reward complexity can impact pollinators' perception, learning, and decision-making in interesting and sometimes unexpected ways. A cognitive perspective can shed new insight into the functions of floral reward complexity and bridge the fields of animal behavior and plant ecology. The cognitive ecology of pollination is most often studied using simple rewards, yet flowers often contain multiple types of chemically complex rewards, each varying along multiple dimensions of quality. In this review we highlight ways in which reward complexity can impact pollinator cognition, demonstrating the need to consider ecologically realistic rewards to fully understand plant–pollinator interactions. We show that pollinators' reward preferences can be modulated by reward chemistry and the collection of multiple reward types. We also discuss how reward complexity can mediate pollinator learning through a variety of mechanisms, both with and without reward preference being altered. Finally, we show how an understanding of decision-making strategies is necessary to predict how pollinators' evaluation of reward options depends on the other options available. [ABSTRACT FROM AUTHOR]

Faced with pollinator declines, cities could serve as refuges for biodiversity conservation by managing floral resources in public green spaces. Ornamental plants could play an important role in attracting pollinators because they form part of urban floral management. However, knowledge of how their floral traits respond to drought is lacking, and it is unknown whether they will be suitable for pollinators under future climates. The main objective of this study was to determine the covariation of floral traits of ornamental plant species and effects of drought on them. To this end, in a city greenhouse we measured floral traits of eight ornamental species commonly used in urban green spaces in France. We subjected the plants to a control treatment or a drought treatment, reducing the volume and frequency of watering. We observed interspecific variability in floral traits among these species and a change in covariation between the traits pollen quantity and nectar quantity in the drought treatment. Drought influenced morphological traits related to floral display more than other floral traits, with mean decreases of 28 % in floral height, 35 % in floral area and 58 % in the number of floral units. Ornamental plants seemed attractive to different morphotypes of pollinators depending on their floral unit number, nectar sugar concentration or nectar tube depth, with most visits made by Hymenoptera. These results are expected to encourage green-space managers to select urban plants according to their functional characteristics and adapt their choice of plants to climate change. [ABSTRACT FROM AUTHOR]

• Massonia grandiflora flowers are visited and pollinated by mice and elephant-shrews. • Pollen surrogate transfer from anthers to stigma proves mammal pollination. • M. grandiflora flowers show adaptations to non-flying mammal pollination. • Choice experiments showed that nectar scent is attractive for the mammals. • Crypsis, viscous and bitter nectar might deter bees and birds. Pollination by small non-flying mammals occurs in Africa, Australia, Asia and the Neotropics. One hotspot is in the winter rainfall zone of the Cape Floral Region of South Africa. This phenomenon is known for a handful of plant lineages, of which one comprises geoflorous monocots including the tribe Hyacintheae of the Asparagaceae. Small mammal pollination has been documented for four members of the Hyacintheae. A further representative of this taxon, Massonia grandiflora , is hypothesized to be pollinated by small mammals as it shares floral characters with other plants adapted to small mammal pollinators. The study aims at the identification of the pollinators and the characterisation of the floral features of M. grandiflora as well as to experimentally test whether the plants' nectar scent is an attractant to the flower visitors. With direct observations and video monitoring, we demonstrate the fitting between the head of elephant-shrews and rodents and the bowl-shaped flowers with protruding stigmas and styles as well as pollen transfer from the plants' anthers on the animals' body parts that made contact with the stigma. We experimentally show the transfer of pollen surrogates by elephant-shrews and rodents from the anthers via the animals' fur onto the stigmas of conspecific flowers. Pollen loads on the animals' snout and in their faeces represent indirect evidence for flower visits. Insects and birds were not observed as nectar consumers. Choice tests revealed that mice and elephant-shrews are attracted by nectar scent. We conclude that the fragrant nectar attracts mice and elephant-shrews as pollinators, whereas its bitterness and viscosity as well as the flowers' visual crypsis might filter out insects (and birds) as less effective pollinators. [ABSTRACT FROM AUTHOR]

An increasing number of recent studies show that nectar-inhabiting microorganisms influence plant fitness by mediating interactions between plants and pollinators. However, whether the effects of nectar microbes extend beyond pollination to affect subsequent stages of plant reproduction remains largely unknown. This study aims to explore whether nectar microbes can indirectly affect fruit consumption by birds, which can be essential for seed dispersal and germination. Wild flowers of Eurya japonica trees were experimentally inoculated with the nectar-inhabiting yeast Metschnikowia reukaufii and the nectar-inhabiting bacterium Acinetobacter boissieri , both of which had been previously isolated frequently from E. japonica flowers. In this experiment, I examined whether these microbes changed female reproductive success of the understory tree. Experimental inoculation of flowers with yeasts decreased fruit and seed set compared to those inoculated with bacteria, and the control. Furthermore, fruits with higher seed set tended to be larger, and larger fruits were more likely to be consumed by seed-dispersing birds, including the Japanese white-eye Zosterops japonica, the brown-eared bulbul Hypsipetes amaurotis , and the Daurian redstart Phoenicurus auroreus. These results suggest that nectar-inhabiting microorganisms have the potential to affect plant reproduction by influencing not only plant-pollinator interactions, but also by indirectly modifying plant-frugivore interactions via changes in plant-pollinator interactions. [ABSTRACT FROM AUTHOR]

The volatile markers and aroma properties of unifloral safflower honey in Xinjiang, China were identified for the authentication. An untargeted metabolomics analysis was performed to compare the volatile components in safflower honey with those in four other unifloral honey and the nectar plants of safflower honey through headspace solid-phase microextraction–chromatography–mass spectrometry. Tentative markers, including benzaldehyde, longifolene, and cedrol, were comprehensively screened through variable importance in projection based on orthogonal partial least-squares discrimination analysis, nectar origin volatile components analysis, and odor characteristics analysis. A targeted quantitative analysis of potential volatile compound contents within safflower honey between 2021 and 2023 provided valuable evidence for differentiating safflower honey and other honey. Furthermore, bacterial inhibition tests showed that safflower honey exhibits inhibitory activity against Escherichia coli , with efficacy comparable to control. The reliable volatile markers, longifolene, and cedrol, enhance safflower honey's antibacterial effect. • Three volatile compounds were discovered as volatile markers for unifloral safflower honey. • A combined untargeted and targeted GC–MS method was used for marker identification. • A flavor wheel was constructed for safflower honey based on OAV and OCR. • The volatile markers may make contribution to the antibacterial activity of safflower honey. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hemolymph osmolality can serve as a readout for insect water-balance physiology. • Hemolymph osmolality of 350–400 mmol/kg suggests a healthy satiated state. • The hemolymph osmolality above 500 mmol/kg indicates osmotic stress. • Synthetic or Authentic nectar fed moths maintain healthy osmolality. • A single nectar or water meal can rescue osmotic stress in starved moths. Climate-induced shifts in flowering phenology can disrupt pollinator-floral resource synchrony, especially in desert ecosystems where rainfall dictates both. However, baseline metrics to gauge pollinator health in the wild amidst rapid climate change are lacking. Our laboratory-based study establishes a baseline for pollinator physiological state by exploring how osmotic conditions influence survivorship in a desert hawkmoth pollinator, Manduca sexta. We sampled hemolymph osmolality from over 1000 lab-grown moths at 20 %, 50 %, and 80 % ambient humidity levels. Starved moths maintained healthy osmolality of 350–400 mmol/kg for 1–3 days after eclosion regardless of ambient humidity, but it sharply rose to 550 mmol/kg after 4–5 days in low and moderate humidity, and after 5 days in high humidity. Starved moths in low humidity conditions perished within 5 days, while those in high humidity survived twice as long. Moths fed synthetic Datura wrightii nectar, synthetic Agave palmeri nectar, or water, maintained osmolality within a healthy range of 350–400mmol/kg. The same was true for moths fed authentic floral nectars from Datura and Agave plants, although moths consumed more synthetic than authentic nectars, possibly due to non-sugar constituents. Simulating a 4-day mismatch between pollinator emergence and nectar availability, a single nectar meal osmotically rescued moths under dry ambient conditions. Our findings highlight hemolymph osmolality as a rapid and accurate biomarker distinguishing dehydrated from hydrated states in insect pollinators. [ABSTRACT FROM AUTHOR]

Honey adulteration is a subject of great concern worldwide. The compound 3-methoxytyramine (3-MT) is one of the biomarkers used to determine adulteration or contamination with sugar, syrups, and other products of beetroot (Beta vulgaris) from Amaranthaceae family. However, there is scientific evidence of the presence of 3-methoxytyramine in other species of this family, some of which, reported in Cuba. As honey plants, bees use them to carry nectar and pollen to hives to make honey, therefore, there is a possibility to detect 3-methoxytyramine in these samples, not only in Cuban's honeys samples, but also worldwide. [ABSTRACT FROM AUTHOR]

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

Floral nectar and pollen commonly contain diverse secondary metabolites. While these compounds are classically thought to play a role in plant defense, recent research indicates that they may also reduce disease in pollinators. Given that parasites have been implicated in ongoing bee declines, this discovery has spurred interest in the potential for 'medicinal' floral products to aid in pollinator conservation efforts. We review the evidence for antiparasitic effects of floral products on bee diseases, emphasizing the importance of investigating the mechanism underlying antiparasitic effects, including direct or host-mediated effects. We discuss the high specificity of antiparasitic effects of even very similar compounds, and highlight the need to consider how nonadditive effects of multiple compounds, and the post-ingestion transformation of metabolites, mediate the disease-reducing capacity of floral products. While the bulk of research on antiparasitic effects of floral products on bee parasites has been conducted in the lab, we review evidence for the impact of such effects in the field, and highlight areas for future research at the floral product-bee disease interface. Such research has great potential both to enhance our understanding of the role of parasites in shaping plant-bee interactions, and the role of plants in determining bee-parasite dynamics. This understanding may in turn reveal new avenues for pollinator conservation. [Display omitted] [ABSTRACT FROM AUTHOR]

• Aloe reitzii var. reitzii bears red flowers in summer, suggesting bird pollination. • Four specialist and five generalist nectar-feeding bird species visit the aloe. • Temporally separated sunbirds and weavers co-dominate day visitation. • Nectar properties reflect generalist nectivorous bird preferences. • Honeybees and beetles also visit during the day, and hawkmoths visit at night. Aloe reitzii var. reitzii is a summer-flowering (February–March) succulent, endemic to a restricted range within the heavily transformed grasslands of eastern South Africa. Floral structure and nectar properties suggest bird-pollination. This study investigated the temporal visitation events of birds to this aloe. Extensive camera observations during the 2017 flowering season (23 days) identified both specialist and generalist nectarivorous birds (n = four and five species respectively) as regular diurnal aloe visitors. Malachite Sunbirds (Nectarinia famosa) accounted for 49% of all visits, while Cape Weavers (Ploceus capensis) made up 41% of all visits; these species co-dominate visitation of the specialist and generalist avian feeding guilds respectively. In addition, visitation by each guild was separated temporally to some extent, with generalists mostly visiting early in the day, while specialists dominate afternoon visitation. Nectar volume (overall unbagged mean = 48.67 ± 4.70 µL) and concentration (overall unbagged mean = 10.68 ± 0.21% w/w) remains consistent throughout the day, and are within generalist nectar-feeding bird preferences, which may explain the abundance of Cape Weavers, despite floral morphological traits matching those of specialist nectar feeders. While many summer-flowering aloes are primarily insect- or sunbird-pollinated, Cape Weavers may be supplementing their diets with A. reitzii var. reitzii nectar, and potentially playing a crucial role in pollination. [ABSTRACT FROM AUTHOR]

• Floral traits have been used to hypothesise the occurrence of long-proboscid fly (LPF) pollination in the genus Erica. • Erica aristata is shown to be visited exclusively by Prosoeca rubicunda (Nemestrinidae) in multiple years. • Captured flies bore tetrads of Erica pollen on their heads. • Flowers from which flies were excluded set no fruit. • This is the first empirical evidence for LPF pollination in Erica and the Ericaceae. Long-proboscid fly (LPF) pollination has been recorded in multiple plant lineages in South Africa. However in the large and morphologically diverse genus Erica, evidence for LPF pollination is limited to predictions based upon floral syndromes as well as anecdotal observation and limited citizen science records. Here we use breeding system experiments, pollinator exclusion, remote camera traps, spectral analysis and field observation in the Klein River Mountains, Western Cape Province, South Africa, to demonstrate this mode of pollination in the range-restricted taxon Erica aristata. This species has long narrow corolla tubes with narrow opening and contrasting white and crimson pink petals. Flowers were visited and pollinated exclusively by one long-proboscid fly species, Prosoeca rubicunda (Nemestrinidae) over four years at this study site. Breeding experiments showed that E. aristata is not self-compatible and pollinator exclusion experiments indicate that pollinator visits were required for seed-set. Low nectar volume and moderately high nectar sugar concentration were consistent with other long-proboscid fly-pollinated plant species in the Cape. This study represents the first confirmed instance of long-proboscid fly-pollination in the genus Erica. [ABSTRACT FROM AUTHOR]

• The BeeBox automatically records feeding time and occurrence in insects. • This reveals circadian rhythm in feeding in bees. • This rhythm is lost in animals kept in constant light. • Constant light also induces higher mortality. In honey bees, most studies of circadian rhythms involve a locomotion test performed in a small tube, a tunnel, or at the hive entrance. However, despite feeding playing an important role in honey bee health or fitness, no demonstration of circadian rhythm on feeding has been performed until recently. Here, we present the BeeBox, a new laboratory platform for bees based on the concept of the Skinner box, which dispenses discrete controlled amounts of food (sucrose syrup) following entrance into an artificial flower. We compared caged groups of bees in 12 h-12 h light/dark cycles, constant darkness and constant light and measured average hourly syrup consumption per living bee. Food intake was higher in constant light and lower in constant darkness; mortality increased in constant light. We observed rhythmic consumption with a period longer than 24 h; this is maintained in darkness without environmental cues, but is damped in the constant light condition. The BeeBox offers many new research perspectives and numerous potential applications in the study of nectar foraging animals. [ABSTRACT FROM AUTHOR]

Although Boraginaceae have been classified as good sources of nectar for many insects, little is still known about their nectar and nectaries. Thus, in the present contribution, we investigated the nectar production dynamics and chemistry in Borago officinalis L. (borage or starflower), together with its potential interaction capacity with pollinators. A peak of nectar secretion (∼5.1 µL per flower) was recorded at anthesis, to decrease linearly during the following 9 days. In addition, TEM and SEM analyses were performed to understand ultrastructure and morphological changes occurring in borage nectary before and after anthesis, but also after its secretory phase. Evidence suggested that nectar was transported by the apoplastic route (mainly from parenchyma to epidermis) and then released essentially by exocytotic processes, that is a granulocrine secretion. This theory was corroborated by monitoring the signal of complex polysaccharides and calcium, respectively, via Thiéry staining and ESI/EELS technique. After the secretory phase, nectary underwent degeneration, probably through autophagic events and/or senescence induction. Furthermore, nectar (Nec) and other flower structures (i.e., sepals, gynoecia with nectaries, and petals) from borage were characterized by spectrophotometry and HPLC-DAD, in terms of plant secondary metabolites, both at early (E-) and late (L-) phase from anthesis. The content of phytochemicals was quantified and discussed for all samples, highlighting potential biological roles of these compounds in the borage flower (e.g., antimicrobial, antioxidant, staining effects). Surprisingly, a high significant accumulation of flavonoids was registered in L-Nec, with respect to E-Nec, indicating that this phenomenon might be functional and able to hide molecular (e.g., defence against pathogens) and/or ecological (e.g., last call for pollinators) purposes. Indeed, it is known that these plant metabolites influence nectar palatability, encouraging the approach of specialist pollinators, deterring nectar robbers, and altering the behaviour of insects. • Ultrastructure of Borago officinalis L. (borago) nectary was characterized. • A granulocrine secretion mechanism was associated to borage nectary. • Production dynamics and phytochemical profile of borago nectar was investigated. • Ecological and molecular roles for the plant metabolites found in borage nectar were hypothesized. [ABSTRACT FROM AUTHOR]

Anagyrus vladimiri (Hymenoptera: Encyrtidae) is the main parasitoid of Planococcus citri (Hemiptera: Pseudococcidae), which is one of the most important pests of citrus crops in the Mediterranean Basin. Pesticide residue on trees and in the nectar of wildflowers growing in citrus orchards might cause side effects in beneficial insects. In the present study, we assessed the effects of six systemic pesticides (acetamiprid, dimethoate, cyantraniliprole, flupyradifurone, spirotetramat and sulfoxaflor) on the survival and progeny of A. vladimiri. Anagyrus vladimiri fed on the pesticide solutions and on the nectar of Fagopyrum esculentum Moench plants that had been watered with a solution containing these pesticides. Acetamiprid, dimethoate, flupyradifurone and sulfoxaflor increased female mortality more than the control (water) after 6h; after A. vladimiri consumed these pesticides, female mortality ranged from 62% to 73%. Cyantraniliprole had no immediate toxic effect on parasitoid survival but caused mortality after 15 days. All tested pesticides except flupyradifurone and spirotetramat reduced parasitoid progeny. After six days of feeding on F. esculentum nectar of plants watered with a pesticide solution, significantly increased female mortality was observed with dimethoate (96%), spirotetramat (80%), acetamiprid (62%), cyantraniliprole (62%) and sulfoxaflor (50%). Progeny was reduced in females that fed on plants treated with spirotetramat and dimethoate. These results demonstrate that some of these insecticides can have lethal or sublethal effects on A. vladimiri by both routes of exposure, via direct or indirect pesticide consumption through the nectar of treated plants. • Pesticides that systemically reach the nectar can negatively affect parasitoids. • Anagyrus vladimiri fitness was negatively affected by direct pesticide consumption. • Treated plants nectar consumption have lethal or sublethal effects on A. vladimiri. • Pesticide sprays drift and runoff are an entomofauna toxic exposure route. • Systemic pesticides have shown different behavior through buckwheat nectar. [ABSTRACT FROM AUTHOR]

[Display omitted] • Generation and degradation mechanism of pigments in Leucosceptrum canum. • Phenol metabolism and amino acid degradation were discovered together. • Leucosceptrum canum nectar is a rare dark brown alkaline nectar. • Identification of pigments in nectar by combining LC-MS and chemical synthesis. • Amino acid quinone conjugates and Leucosceptrum canum honey are non-toxic. Leucosceptrum canum nectar (LCN) emerges as a novel food resource, distinguished by its unique dark brown hue. This study delves into the composition and toxicity assessment of novel pigments within LCN. Through liquid chromatography-tandem mass spectrometry (LC-MS/MS) and chemical synthesis, seventeen 2,5-di-(N-(-)-prolyl)- para -benzoquinone (DPBQ) analogs in LCN were identified. These compounds are synthesized in LCN via the Michael addition reaction, utilizing p -benzoquinone (BQ), derived from phenol metabolism, and amino acids as substrates in an alkaline environment (pH = 8.47 ± 0.06) facilitated by dissolved ammonia and the presence of alkaloids. Analytical techniques, including principal component analysis (PCA), orthogonal partial least squares discrimination analysis (OPLS-DA), and volcano plot analysis, were employed to investigate DPBQ analog degradation within the nectar and honey's unique environments. Toxicity assays revealed that DPBQ analogs exhibited no toxicity, displaying a significant difference in toxicity compared to the precursor compound BQ at concentrations exceeding 25 μM. [ABSTRACT FROM AUTHOR]

• There was no effect of patch size on visitation rates in Erica discolor. • Proportion of viable E. discolor seeds was not lower in small compared to large patches. • Small fragments could be crucial for the persistence of ornithophilous plant populations. Small or isolated plant populations might be expected to provide limited nectar resources to attract or sustain pollinators. We determined whether the plant-pollinator mutualism between the obligate out-crossing ornithophilous species Erica discolor , and its pollinators was resilient to habitat fragmentation. To do this we recorded pollinator visitation rates (using % flowers with at least one visit as a proxy) and seed set in patches of different sizes and degree of isolation in the easternmost section of the Cape Floristic Region, South Africa. For E. discolor , there was no negative effect of patch size and isolation on visitation rates. Plants in small patches (< 100 ha) did not have lower proportions of viable seeds compared to plants in large patches (> 240 ha). Our findings suggest that conserving small isolated fragments is important in maintaining ornithophilous plant populations. [ABSTRACT FROM AUTHOR]

Nectar is the most important reward offered by flowering plants to pollinators for pollination services. Since pollinator decline has emerged as a major threat for agriculture, and the food demand is growing globally, studying the nectar gland is of utmost importance. Although the genetic mechanisms that control the development of angiosperm flowers have been quite well understood for many years, the development and maturation of the nectar gland and the secretion of nectar in synchrony with the maturation of the sexual organs appears to be one of the flower's best-kept secrets. Here we review key findings controlling these processes. We also raise key questions that need to be addressed to develop crop ecological functions that take into consideration pollinators' needs. The nectary gland mediates the interactions between flowering plants and their pollinators and defenders. Nectar is the main reward to pollinators for pollination services. Understanding the molecular basis of nectary development has economic and evolutionary significance. In rosids and asterids, CRABS CLAW (CRC) is a master regulator of nectary development. In addition, CRC orchestrates carpel development and floral meristem termination and is controlled by the B-, C-, and E-class genes. In basal eudicots, the STY genes play the key role in nectary formation through the auxin biosynthesis pathway. [ABSTRACT FROM AUTHOR]

Like other invertebrates, honey bees too are poikilothermic animals; they cannot regulate their body temperature and they have to undergo a period of inactivation when atmospheric temperature is un-tolerable. During this period, their nutritional requirements and metabolic activities are minimized due to highly restricted foraging activities. The egg-laying by queen and rearing of unsealed and sealed brood are decreased, however their extent is governed by the quantum of stored food available. The problems of deleterious influence of adverse weather conditions and non-availability of bee flora all round the year, in a particular locality, have been realized by the researchers/beekeepers and migration concept has been developed to solve this problem. But again, migration itself is not an easy task. The provision of artificial feeding as an alternate of migration. Scientists all over the world have formulated different artificial food recepies for bees on the basis of nutrient composition of honey and pollen, acceptability, palatability, digestibility and affordability of ingredients. This may help to maintain all colony parameters enough to derive maximum advantage of forthcoming floral rich season. However, a standard balanced diet for commercial beekeeping that is accepted worldwide is still awaited. [ABSTRACT FROM AUTHOR]

The floral morphology and pollination of S. guineense subsp. macrocarpum were investigated on ten trees selected for a study of floral phenophases in the natural forest of Bassila, located in the Sudano-Guinean zone (Benin). For the floral analysis, the two stages considered were flower buds for preflowering data and open flowers for flower data. To determine the pollination mode and identify main pollinators, two stages were considered, namely flower bud and initiated fruits. The fruit set, autogamy and allogamy rate were assessed. Results show that several flower morphological traits predispose this species to selfing and cross pollination, including hermaphroditism and a long anther–stigma distance. The symmetry is actinomorphic with a floral receptacle adnate to the ovary. The latter is inferior, bicarpellary and bilocular syncarpous and contains 18–22 ovules on an axile placenta. Only a single ovule is fertilized and becomes a seed. Visitors frequently registered on the flowers of S. guineense subsp. macrocarpum are exclusively insects belonging to six orders, including Diptera (26%), Hymenoptera (24%), Lepidoptera (19%). The mean fruit set was 0.47 ± 0.10 for the open-pollination experiments and 0.27 ± 0.12 for autogamous self-pollination. The autogamy rate was 57.45% and the allogamy rate 42.55%. This study confirms that S. guineense subsp. macrocarpum is predominantly autogamous. Self-compatibility is not for exceptional species, but a dominant characteristic of the genus Syzygium. The viability of the pollen grains and receptivity of the stigma at each flowering stage should be further studied. [ABSTRACT FROM AUTHOR]

Anthropophilic female mosquitoes are well known for their strong attraction to human hosts, but plant nectar is a common energy source in their diets. When sugar sources are scarce, female mosquitoes of some species can compensate by taking larger and more frequent blood meals. Male mosquitoes are exclusively dependent on plant nectar or alternative sugar sources. Plant preference is likely driven by an innate attraction that may be enhanced by experience, as mosquitoes learn to recognize available sugar rewards. Nectar-seeking involves the integration of at least three sensory systems: olfaction, vision and taste. The prevention of vector-borne illnesses, the determination of the mosquitoes' ecological role, and the design of efficient sugar-baited traps will all benefit from understanding the molecular basis of nectar-seeking. For many anthropophilic mosquito species, females benefit from nectar-feeding as they become reproductively mature yet they often skip a nectar meal when given access to a human host during this period. Male mosquito survival and reproductive success requires access to sugar sources. Aedes aegypti and Anopheles gambiae females can survive without sugar meals by increasing their blood consumption. Unlike vertebrate host preference, nectar choices are flexible and often unpredictable. Nonetheless, mosquitoes have an innate preference for certain combinations of volatiles typically rich in terpenes and aromatic aldehydes that are associated with plants. Mosquitoes identify sugar sources using visual, olfactory, and gustatory cues; several plant-related volatiles are detected by the odorant receptors (ORs) and their obligate co-receptor orco. [ABSTRACT FROM AUTHOR]

• Mango crop exhibits floral attractants to pollinators in protected cultivation which have been described and evaluated here. • Mango flowers in protected cultivation show colorations and patterns under UV that are attractive to pollinators. • Staminate flowers are the predominant flowers in panicles, but hermaphrodite flowers occupy more favorable positions for pollination. • Nectar quantity and nutritional composition varies between hermaphrodite and staminate mango flowers. • Pollen quantity and nutritional composition is similar in hermaphrodite and staminate mango flowers. Floral attractants and rewards are essential in plant-pollinator interaction, pollen transfer to and from the flowers, and hence in crop production. In this trial, we determined the attractants and rewards of mango 'Osteen' cultivated under a plastic greenhouse. The attractants analyzed were inflorescence architecture and compactness, flower number, size and color patterns. Rewards determined were pollen quantity and its nutritious value and nectar volume and composition. The results show that mango forms panicles with more staminate than hermaphrodite flowers, but the latter are of higher size, more exposed to pollinator activity, and preferentially located in a better-nurtured position within the inflorescence. Pollen produced by staminate and hermaphrodite flowers was similar in quantity and quality. On the contrary, hermaphrodite flowers produced more nectar, likely because of the larger size of their nectary disks. Pollen and nectar present 17 and 22 metabolites, respectively, including carbohydrates, amino acids, and organic acids. Our study provides, for the first time, solid information about the floral attractiveness and rewards of mango cultivated under plastic greenhouses. This will help to understand the possible adaptations required for pollinating this crop under protected cultivation. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate the effect of ultrasound (US), UVC radiation, and combined US+UVC treatments on the inactivation of total aerobic mesophilic bacteria (TAMB) and mold and yeast in orange juice and mango nectar. The microbial inactivation after each treatment, physicochemical and sensory properties of treated products, and the microbial response during their storage at 4 °C for 12 days were assessed. Fresh squeezed orange juice and mango nectar were treated by US, UVC, or US+UVC treatments for 20 min at 15 °C; the initial TAMB and mold and yeast counts were determined. The combined treatment US+UVC showed a better inactivation level in TAMB, molds, and yeasts in orange juice and mango nectar, resulting in lower microbial counts at the storage end. Titrable acidity, °Brix, and pH remained unchanged, while ascorbic acid losses and color changes were observed. Additionally, the sedimentation index (SI) was analyzed during the storage of orange juice, observing that US+UVC reduced the SI and stabilized the orange juice for 12 days. For all tested conditions, mango nectar preserved its sensory properties. Combining food processing technologies such as ultrasound (US) and UVC radiation can improve the process's effectiveness. The US+UVC treatment enhanced the microbial inactivation (total aerobic mesophilic bacteria and mold and yeast) of orange juice and mango nectar, reduced the orange juice's sedimentation index during storage, and did not modify the sensory properties of mango nectar. Thus, the combined US+UVC treatment is an alternative to sustainably preserving and stabilizing orange juice and mango nectar. • Combine ultrasound +UVC radiation treatment improves microbial inactivation in drinks. • Ultrasound, UVC radiation, or its combination keep mango nectar's sensory properties. • Combine ultrasound +UVC radiation treatment reduces sedimentation in orange juice. [ABSTRACT FROM AUTHOR]

[Display omitted] • Our AI-based monitoring technology identified honeybees with pollen accurately. • Mechanistic simulations showed the underlying reason for pollen foraging reduction. • Pollen foragers spent significantly more time completing their foraging trips. • Neonicotinoids affected nectar and pollen foragers in a colony differently. • Foraging tasks of honeybees influenced their susceptibilities to toxicants. Honeybees (Apis mellifera) as pollinators are of economic and ecological importance to global agriculture and natural ecosystems. However, honeybees are being threatened by highly effective pesticides such as neonicotinoids, which can have detrimental impacts on honeybee foraging in particular. In a colony, nectar and pollen foragers play distinct roles in sustaining the colony. Despite evidence of sub-lethal effects of neonicotinoids on individual honeybees, little is known about how neonicotinoids affect the foraging behaviour of an entire colony. Here, we conducted a field study using our innovative artificial intelligence (AI)-based automated monitoring technology to investigate the effects of the neonicotinoid imidacloprid at field-realistic sub-lethal doses on colony foraging behaviour. A mechanistic simulation model (BEEHAVE) was then used to reproduce and interpret field observations, and further identify the plausible mechanisms underlying the empirical findings. Surprisingly, the field study revealed that imidacloprid greatly reduced pollen foraging but not nectar foraging. In addition, no lethal effects on honeybees were observed. The simulations showed that the time spent by pollen foragers on completing their foraging trips was significantly increased, which subsequently decreased the number of pollen foraging trips per day, thereby reducing pollen foraging at the colony level. This suggests that pollen and nectar foraging may require different energetic costs, cognitive functions, and/or gene expressions, which implies different susceptibilities of pollen and nectar foragers to chemical stressors. As pollen foraging is essential for brood rearing, exposure to sub-lethal concentrations of neonicotinoids, together with other stressors, may affect colony survival and resilience more than previously thought. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sedentary moths preferentially allocated nectar sugars to fat body over flight muscle. • Males maintained levels of allocated nectar sugars in the flight muscle longer than females. • Sex did not affect crop-emptying rate in sedentary moths; Crops were emptied 6 h after a nectar meal. • Flight did not significantly alter allocation patterns in either sex, but did increase crop-emptying rate in females. In nectivorous pollinators, timing and pattern of allocation of consumed nectar affects fitness traits and foraging behavior. Differences in male and female behaviors can influence these allocation strategies. These physiological patterns are not well studied in Lepidoptera, despite them being important pollinators. In this study we investigate crop-emptying rate and nectar allocation in Manduca sexta (Sphingidae), and how sex and flight influence these physiological patterns. After a single feeding event, moths were dissected at fixed time intervals to measure crop volume and analyze sugar allocation to flight muscle and fat body. Then we compared sedentary and flown moths to test how activity may alter these patterns. Sedentary males and females emptied their crops six hours after a feeding event. Both males and females preferentially allocated these consumed sugars to fat body over flight muscle. Moths began to allocate to the fat body during crop-emptying and retained these nutrients long-term (four and a half days after a feeding event). Males allocated consumed sugar to flight muscles sooner and retained these allocated nutrients in the flight muscle longer than did females. Flight initiated increased crop-emptying in females, but had no effect on males. Flight did not significantly affect allocation to flight muscle or fat body in either sex. This study showed that there are inherent differences in male and female nectar sugar allocation strategies, but that male and female differences in crop-emptying rate are context dependent on flight activity. These differences in physiology may be linked to distinct ways males and females maximize their own fitness. [ABSTRACT FROM AUTHOR]

• The hybrids develop functional nectaries. • Nectar volume appears to depend of mucilage and starch reserves. • Nectar volume and sugar concentration show interspecific variation. • The hybrids show potential hybrid vigor in terms of sugar concentration. Variation in the quantity and quality of reward substances produced by flowers influences reproductive success in angiosperms. In this study, a comparative analysis of nectaries and nectar traits (volume, concentration and sugar composition) was performed on the hybrid Cephalocereus columna-trajani × C. tetetzo and its parental species to identify phenotypic variation that could affect reproductive success. The presence of nectarostomata and two types of nectary cells are significant, as well as the presence of xylem and phloem. Furthermore, possible interspecific differences in the amount of starch and mucilage may be relevant. Interspecific variation in nectar volume and concentration was found, with the hybrid exhibiting the highest concentration. All three taxa presented hexose-dominated nectar. In conclusion, C. columna-trajani × C. tetetzo, like its parental species has a functional and anatomically well-formed nectary. Differences in traits such as the amount of starch and mucilage associated with nectar volume, in combination with differences in nectar concentration could have potential consequences for fitness. Our results confirm previous reports on the development of functional structures in hybrid flowers and serve as the basis for future studies testing whether the differences observed here govern the dynamics of competition in hybridization zones. [ABSTRACT FROM AUTHOR]

• Sweeteners and copigment sources had significant effects on color of sour cherry nectar. • Addition of gallic acid and pomegranate rind extract increased anthocyanin stability. • Rose leaf extract increased stability of color density by up to 117%. • Pomegranate rind extract resulted in the lowest turbidity and turbidity formation rate. • Pomegranate rind extract is recommended for enrichment and stability of colour. Effects of various co-pigment sources [gallic acid (GA), rose leaf extract (RLE), cherry stem extract (CSE), pomegranate rind extract (PRE) and green tea extract (GTE)] on anthocyanin content, colour, and turbidity in sour cherry nectar (SCN), sweetened with sucrose (SCNS), maltose syrup (SCNM) or honey (SCNH), were investigated during storage at 20 °C. Co-pigment sources were associated with increases in λ max (up to 4.1 nm), colour density (up to 22%), and polymeric colour (up to 1.7 times). Among the co-pigment sources, GA and PRE were associated with the greater anthocyanin stabilities in SCNS and SCNH. Moreover, the lowest turbidity, at the beginning of storage, and turbidity formation rate, throughout storage, were observed in SCNS, SCNM and SCNH containing PRE. When the changes in A max , λ max , polymeric colour, colour density, and turbidity were considered together, PRE was the best co-pigment source, regardless of the sweetener used. [ABSTRACT FROM AUTHOR]

Highlights • A PLS2-DA build on 1H NMR data of organic extracts revealed variations among production zones of EU acacia honeys. • NMR geographical assessment of EU acacia honeys based on floral secondary markers. • A PLS2 model defines the fractions of Italian and East European acacia honeys in blends. Abstract A geographical discrimination of honey is an important prerequisite for quality and authenticity control. Here, we present a method based on an NMR-metabolomic analysis of organic extracts for a geographical discrimination of commercial European acacia honeys found on the Italian market. All 234 analysed samples show the characteristic 1H NMR profile of acacia (Robinia pseudoacacia) honey. However, a PLS2-DA model revealed variations among production zones allowing the successful geographical differentiation with a 100% of overall correct classification rate. Moreover, a PLS2 model is able to predict the proportions in binary blends of Italian and Eastern European acacia honeys. The geographical distinction and the possibility to characterize the content of blends derive from different markers content originating from minor nectar contributions of the acacia-accompanying flora. [ABSTRACT FROM AUTHOR]

Ongoing debate about specialisation vs generalisation in plant–pollinators interactions highlights the reliability of pollination syndrome traits as predictors of the primary pollinator of a species. The South African Watsonia knysnana (Iridaceae) is a case in point as its tubular corolla is consistent with ornithopilous floral traits to attract sunbirds (specialist nectarivore passerines) but the range of colours exhibited covers syndromes that would predict both birds and insects. From exclusion experiments we identified sunbirds as the most effective pollinators of W. knysnana with honeybees playing a minor role, if any. In addition, the nectar properties (concentration and volume) conform to plants pollinated mainly by specialist nectarivorous birds. • Watsonia knysnana is visited by both Insects and sunbirds in the field. • Sunbirds are the main pollinators of Watsonia knysnana. • Watsonia knysnana sets more fruits and more viable seeds when sunbirds are not excluded. • Watsonia knysnana produces small amounts of dilute nectar. [ABSTRACT FROM AUTHOR]

Camu-camu is a red berry rich in bioactive compounds such as ascorbic acid and anthocyanins. In this study, the main objective was to evaluate the effect of thermosonication on the physicochemical changes of camu-camu nectars, alterations such as those in quality parameters (pH, titratable acidity, soluble solids and cloud value), vitamin C, antioxidant activity, anthocyanin content, phenolic compounds, enzymes (PPO and POD) color parameters (L*, a*, b* and ΔE*) and microbiological quality. The thermosonication improved the bioavailability of the bioactive compounds, increased the cloud value and maintained the physicochemical properties of the camu-camu nectars. The enzymatic activity was reduced with increasing time and temperature processing. No microorganisms were observed after thermosonication processing. This study shows that thermosonication could be employed as a preservation technique for fruit nectar processing where bioactive compounds retention is desired. [ABSTRACT FROM AUTHOR]

This study was conducted at the apiary of the Beekeeping Research Section at the Sakha Agricultural Research Station, ARC, Kafrelsheikh, and other apiaries in Kafrelsheikh province, during two successive years 2015 and 2016. The study aimed to survey nectar and pollen floral resources in Kafrelsheikh province. Ninty seven plant species belonging to 33 families were recorded as nectar sources, and 82 plant species belonging to 36 families were recorded as pollen sources during the whole year. The largest amount of monthly trapped pollen was obtained during May followed by August. It can be concluded that, beekeepers in Kafrelsheikh province can harvest good honey yield at the end of blooming seasons of citrus (Citrus spp.) during March and April, Egyptian clover (Trifolium alexandrinum L.) during May and June, loofah (Luffa aegyptiaca Mill.) during June to October, cotton (Gossypium spp.) during July and August, and banana (Musa spp.) during August and September. They also, could be trapping pollen loads collected from faba bean (Vicia faba L.) and flax (Linum usitatissimum L.) during January to March, date palm (Phoenix dactylifera L.) during March and April, Egyptian clover during May and June, summer seed watermelon (Citrullus lanatus var. colothynthoides L.) during June and July, loofah and maize (Zea mays L.) during June to November. [ABSTRACT FROM AUTHOR]

Highlights • High pressure homogenization (HPH) of rosehip nectar prevented the pulp sedimentation. • HPH treatment decreased the mean particle size and did not affect zeta potential of rosehip nectar. • HPH treated samples showed shear thinning and weak gel network structure. • HPH treatment improved the nectar stability with minimally affecting bioactive properties. Abstract The effect of high pressure homogenization (HPH) on physical and bioactive properties of rosehip nectar was investigated. Rosehip nectar has a sedimentation problem while waiting on the market shelf during the sale, for solving this problem, nectars were passed 1, 2 and 3 times through 75, 100 and 125 MPa pressures. Mean particle size decreased as pressure and pass number increased (p < 0.05), whereas zeta potential did not change (p > 0.05). Microstructural images revealed that HPH treatment disrupted the cells and caused to release of cell materials to serum. HPH treatment increased the ΔE values (from 2.48 to 6.03). HPH treated samples showed no sedimentation during storage for 15 days. All samples showed shear thinning behavior and were characterized as weak gel network (G′ > G″). Total phenolic content and ascorbic acid results were decreased by HPH treatments due to increasing outlet temperatures of product, however, antioxidant capacity of nectars increased after treatment due to increasing total carotenoid content. This study indicated that HPH treatment could solve the sedimentation problem during shelf life with minimally affecting bioactive and physical properties of rosehip nectar. [ABSTRACT FROM AUTHOR]

Highlights • Bee-originated proteins are predominant proteinaceous components in loquat honey. • Loquat nectar proteome mainly consisted of xylosidase, thaumatin, and chitinase which were not detected in loquat honey. • The zymography of nectar-originated chitinases is a potential marker for honey botanical origin authentication. Abstract Honey, as a commercial product, is a target of adulteration through inappropriate production practices and deliberate mislabelling of botanical origin. Floral nectar protein could be a good marker for determining the source flowers of honey, especially monofloral honeys. Here, nectar and monofloral honey from Eriobotrya japonica Lindl. (loquat) were systematically compared, especially regarding proteomic and enzymatic activity. Using two-dimensional electrophoresis and mass spectrometry, only bee-originated proteins were detected in loquat honey. Xylosidase, thaumatin, and two kinds of chitinases were detected in loquat floral nectar, and their activity in loquat nectar and honey were quantified. Following gel electrophoresis, loquat honey had similar chitinase activity profiles to loquat nectar, but both were clearly distinguishable from Camellia sinensis nectar and Brassica napus honey. To our knowledge, this is the first examination of nectar-origin enzyme activity in honey. Zymography of chitinases is a potential marker for determining or authenticating the botanical origin of honeys. [ABSTRACT FROM AUTHOR]

In this study, a combination of QuEChERS extraction–magnetic solid phase extraction–dispersive liquid-liquid microextraction has been reported for the extraction and preconcentration of different pesticides (diazinon, penconazole, oxadiazon, diniconazole, and fenazaquin) from various vegetable, fruit, and nectar samples followed by gas chromatography–flame ionization detection. The QuEChERS extraction method is used for the extraction of the analytes from the scums of the samples. A few mg of magnetic nanoparticles (Fe 3 O 4 @SiO 2 @ph) are used for the extraction of the analytes dissolved in the juices of the samples. In the following to achieve high enrichment factors a microextraction procedure, dispersive liquid–liquid microextraction, is carried out. The synthesized nanoparticles are characterized by scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectrophotometer. Some important parameters which affect the extraction efficiency such as weight of the magnetic sorbent , vortexing time, elution solvent kind and volume, extraction solvent kind and volume, pH, and salt addition are studied. Under the optimum extraction conditions, limits of detection and quantification were obtained in the ranges of 0.21–0.34 and 0.69–1.12 μg L−1, respectively. The calibration graphs were linear with coefficients of determination ≥0.9930. High enrichment factors (245–351) and good extraction recoveries (49–70%) were obtained. The relative standard deviation was ≤9% for intra– (n = 6) and inter–day (n = 4) precisions. • A new version of MSPE is reported. • It is used for extraction of pesticides from vegetable, fruit and nectar samples. • It is able to extract total amounts of the analytes from the sample juices and scum. • Fe 3 O 4 @SiO 2 @ph MNPs were synthesis and used in preconcentration procedure. • Low LODs and LOQs, high EFs, and good repeatability are advantages of the method. [ABSTRACT FROM AUTHOR]

In recent years, the impact of Plant Protection Products (PPPs) on insect pollinator decline has stimulated significant amounts of research, as well as political and public interest. PPP residues have been found in various bee-related matrices, resulting in governmental bodies worldwide releasing guidance documents on methods for the assessment of the overall risk of PPPs to different bee species. An essential part of these risk assessments are PPP residues found in pollen and nectar, as they represent a key route of exposure. However, PPP residue values in these matrices exhibit large variations and are not available for many PPPs and crop species combinations, which results in inaccurate estimations and uncertainties in risk evaluation. Additionally, residue studies on pollen and nectar are expensive and practically challenging. An extrapolation between different cropping scenarios and PPPs is not yet justified, as the behaviour of PPPs in pollen and nectar is poorly understood. Therefore, this review aims to contribute to a better knowledge and understanding of the fate of PPP residues in pollen and nectar and to outline knowledge gaps and future research needs. The literature suggests that four primary factors, the crop type, the application method, the physicochemical properties of a compound and the environmental conditions have the greatest influence on PPP residues in pollen and nectar. However, these factors consist of many sub-factors and initial effects may be disguised by different sampling methodologies, impeding their exact characterisation. Moreover, knowledge about these factors is ambiguous and restricted to a few compounds and plant species. We propose that future research should concentrate on identifying relationships and common features amongst various PPP applications and crops, as well as an overall quantification of the described parameters; in order to enable a reliable estimation of PPP residues in pollen, nectar and other bee matrices. Image 1 • Only fragmentary datasets of pesticide residue values in pollen and nectar exist. • Poor knowledge on fate and relationship amongst different pesticides in bee products. • Extrapolation between different pesticide applications on residues is not possible. • Manifold parameters influence the pesticide residues in bee products. • Significant need for detailed research on pesticide residues in pollen and nectar. Pesticide residue values within pollen and nectar have potentially significant consequences for the reliability of risk assessments for wild and managed bee populations, however, the reasons and mechanisms underlying variations in residues are poorly understood and require greater investigation. [ABSTRACT FROM AUTHOR]

Beyond its role as a reward for pollinators, floral nectar also provides a habitat for specialized and opportunistic yeasts and bacteria. These microbes modify nectar chemistry, often altering mutualistic relationships between plants and pollinators in ways that we are only beginning to understand. Many studies on this multi-partite system have focused on either yeasts or bacteria without consideration of yeast–bacterium interactions, but recent evidence suggests that such interactions drive the assembly of nectar microbial communities and its consequences for pollination. Unexplored potential mechanisms of yeast–bacterium interactions include the formation of physical complexes, nutritional interactions, antibiosis, signaling-based interactions, and horizontal gene transfer. We argue that studying these mechanisms can elucidate how nectar microbial communities are established and affect plant fitness via pollinators. Floral nectar is inhabited by specialized and opportunistic yeasts and bacteria that can alter the mutualistic relationships between plants and animals. Most previous studies in nectar microbiology have focused on either yeasts or bacteria without consideration of yeast–bacterium interactions. Potential mechanisms of yeast–bacterium interactions in floral nectar include the formation of physical complexes, nutritional interactions, antibiosis, signaling-based interactions, and horizontal gene transfer. The combined action of these mechanisms might have unexpected consequences for the host plants and their floral visitors. [ABSTRACT FROM AUTHOR]

Floral nectar is central to ecology, since it mediates interactions with pollinators, flower-visiting antagonists and microbes through its chemical composition. Here we review how historical assumptions about its ecological meaning were first challenged, then modified and expanded since the discovery of secondary metabolites in nectar. We then explore the origin of specific neuroactive nectar compounds known to act as important insect neurotransmitters, and how advances in the field of bee cognition and plant-microbe-animal interactions challenge such historical views. As all actors involved in the latter interactions are under simultaneous reciprocal selective pressures, their coexistence is characterized by conflicts and trade-offs, the evolutionary interpretation of which suggests exciting new perspectives in one of the longest studied aspects of plant-pollinator interactions. [Display omitted] • The series of hypotheses on the role of nectar is reviewed and collated together. • New discoveries challenge how we think floral visitors use their food environment. • Upon colonization, microbes introduce their own metabolites into the nectar. • Microbe byproducts may act as animal neurotransmitters and influence their behavior. • Future research should address the so called "manipulation for dispersal" hypothesis. [ABSTRACT FROM AUTHOR]

The plant species Paullinia cupana Kunth (Sapindaceae), commonly known as guarana, originates from the central Amazonian Basin and has a long history of local use for its stimulant properties. It is currently commercialized worldwide for its health beneficial properties. The seeds chemical composition has been extensively studied over the years. However, the chemistry of guarana flowers, particularly the nectar content, have been barely investigated. From an ecological perspective, floral nectar and pollen are the primary food rewards for pollinators. In the present study, we investigated the chemical composition of nectar and whole pistillate, and staminate guarana flowers harvested separately. Although guarana is well known for its high concentration of caffeine in its seeds, to the best of our knowledge, this is the first report of caffeine and other methylxanthines as the main constituents of the nectar. The significant difference between guarana floral chemistry, which is more diverse and complex, and nectar chemical profile, which primarily contains methylxanthines, suggests that the presence of these compounds in guarana nectar may have an impact on plant-pollinator interactions, which can affect the fitness of both plants and flower visitors • Caffeine and other methylxanthines are the main constituents of guarana nectar. • Guarana whole floral chemistry is more diverse and complex than nectar. • Caffeine increases the reward memory of some pollinators. • Caffeine may have an impact on pollination of guarana. [ABSTRACT FROM AUTHOR]

Pollen and nectar can be contaminated with a range of pesticides, including insecticides, fungicides, and herbicides. Since these matrices are important food sources for pollinators and other beneficial insects, their contamination can represent a key route of exposure. However, limited knowledge exists with respect to pesticide residue levels and their dynamics in these matrices for many crops and active ingredients (AIs). We used controlled glasshouse studies to investigate the residue dynamics of a systemic (cyprodinil) and a contact (fludioxonil) fungicide in the floral matrices and other plant parts of courgette/zucchini (Cucurbita pepo L.). We aimed to better understand the processes behind residue accumulation and decline in pollen and nectar. Each AI was applied to plants, either by spraying whole plants or by targeted spraying onto leaves only. Samples of pollen, nectar, anthers, flowers, and leaves were taken on the day of application and each subsequent morning for up to 13 days and analysed for residues using LC-MS/MS. Significant differences in residue levels and dynamics were found between AIs and floral matrices. The present study allowed for the identification of potential routes by which residues translocate between tissues and to link those to the physicochemical properties of each AI, which may facilitate the prediction of residue levels in pollen and nectar. Residues of the contact AI declined more quickly than those of the systemic AI in pollen and nectar. Our results further suggest that the risk of oral exposure for pollinators may be considerably reduced by using contact AIs during the green bud stage of plants, but application of systemic compounds could still result in a low, but continuous long-term exposure for pollinators with limited decline. [Display omitted] • Pesticide residue dynamics in pollen and nectar varied between contact and systemic pesticides. • Limited decline of the systemic pesticide in pollen was observed when sprayed prior to flowering. • Relationships between residues in different floral matrices varied depending on the pesticide used. • The temporal variations of residues in pollen and nectar were investigated. [ABSTRACT FROM AUTHOR]

The management of plants and landscapes can affect the reproductive cycle of species through changes in morphology, temporal distribution of resources, and productivity, with ecological implications. In this study, we investigated the influence of management practices on the reproductive phenology and nectar availability of Cereus jamacaru DC, a columnar cactus native to Brazil managed by local people in the Caatinga dry forest. Our results reveal that the traditional management practices alter the quantitative and spatiotemporal distribution of resources (flowers, fruits, and nectar) of individuals of C. jamacaru in the studied Caatinga. All populations exhibited annual patterns of flowering and fruiting. However, individuals of the ex situ managed population showed a distinct temporal distribution pattern of flowering, with flower buds and flowers more regularly distributed throughout the reproductive period, compared to individuals of the in situ and unmanaged populations. Management practices differentially affected the production of flower buds, flowers, and fruits with a positive effect on fruit set in the in situ managed population. In addition, individuals of managed populations presented anticipation in the average date of the emission peaks of flower buds and ripe fruits. Individuals from the in situ managed population had available a greater volume of nectar with a higher sugar concentration per flower (twice as high) compared to the ex situ managed population and unmanaged population. The management practices seem to provide advantageous conditions for individuals of C. jamacaru since they allow higher availability of resources (flowers, nectar, and fruits) for a longer period in the Caatinga dry forest. Thus, management practices can prolong the temporal distribution of flowers and fruits, providing more resources for specialized pollinators (Sphingids) and dispersers (birds, reptiles), which are groups vulnerable to anthropic disturbances and climate changes in the Caatinga dry forest. These practices ultimately contribute to the maintenance of key ecological interactions of other species dependent on these vectors, benefiting the whole plant and animal community in the Caatinga dry forest. [Display omitted] • Traditional management practices alter the distribution of Cereus jamacaru reproductive resources (flowers, fruits, nectar). • Individuals from managed populations presented anticipation of peaks of flower bud emission in relation to unmanaged. • In situ managed population had higher volume and milligrams of sugar in the nectar than ex situ and unmanaged populations. • Management practices in Cereus jamacaru provide higher availability of resources for a longer period in the Caatinga. • In situ management is more advantageous for fruit setting. [ABSTRACT FROM AUTHOR]

• The rare Mediterranean carnation endemic to SW Spain, Dianthus inoxianus mostly relies on a single migrant hawkmoth species for pollination. • Floral traits match behavioral and morphological features of the primary pollinator. • D. inoxianus is self-compatible, and its incomplete protandry would facilitate autonomous selfing, providing reproductive assurance when pollinators become scarce. Plants with specialized pollination systems may be susceptible to reproductive failure when pollinator service is unpredictable. This can influence the selection of floral traits that promote outcrossing in the presence of pollinators and selfing in their absence. Limited evidence exists regarding the association between specialized pollination and reproductive assurance, necessitating further investigation. We studied the reproductive biology of Dianthus inoxianus , a rare Mediterranean carnation endemic to a semi-arid region in SW Spain. D. inoxianus exhibited protandrus flowers and additional phenotypic signs of specialization for nocturnal pollination. Nectar sugar concentration remains relatively constant throughout the day (average 33.4%), while the standing crop varies considerably (average 1.5 μL/flower), peaking in the late afternoon and early evening. Controlled hand pollinations revealed that D. inoxianus is fully self-compatible, with similar reproductive success in autogamous, geitonogamous, and allogamous crosses. However, a small proportion of bagged flowers exhibited autonomous selfing. To assess the impact of presumed nocturnal pollination, we studied reproductive fitness and flower visitors over five years in three populations. Over 210 h of pollinator censuses, the hawkmoth species Hyles livornica and Macroglossum stellatarum , which were mainly dusk-active, accounted for > 95% of flower visits. Fruit and seed set positively correlated with hawkmoth visitation rate across years and populations. Additionally, pollinator exclusion experiments demonstrated that reproduction relies predominantly on nocturnal pollinators. However, under natural conditions, D. inoxianus also showed a non-negligible degree of autonomous self-pollination, with fruit- and seed-set being equivalent in absence of pollinators or under diurnal pollinators. We found evidence of an ecologically specialized pollination system and capacity for autonomous selfing, a combination that may enable the persistence of this taxon in a markedly unpredictable pollination environment. [ABSTRACT FROM AUTHOR]

Honey is a highly-valued food product, appreciated due to its organoleptic and health-promoting properties; which both depend on its botanical provenance. In this study, a collection of nectar honey varieties (acacia, buckwheat, linden, rape, and heather) was subjected to extensive physicochemical, melissopalynological, and molecular analyses, to verify if the latter (qPCR-HRM) can be used as a rapid method for determination of the product's authenticity. To this end, the DNA extracted from the honey pollen grains was subjected to a carefully pre-optimized qPCR-HRM analysis. The effectiveness of extracting DNA templates relied on various factors but a significant role played honey "pollination" degree. The plastidial rbcL barcode was found to be a better option for the taxonomic differentiation with qPCR-HRM when compared to the nuclear targets. The results showed that qPCR-HRM correctly clustered honey samples of the same botanical origin determined by melissopalynology. The qPCR-HRM clustering results were additionally verified by rbcL region sequencing. The most consistent data were obtained for heather honey with over-represented pollen, which results from the generally observed low availability of plastidial DNA in the total DNA extracts. The qPCR-HRM revealed a biological divergence within the honey samples marketed as "acacia", as confirmed by melissopalynology. • Honey botanical origin verified with melissopalynological and qPCR-HRM analyses. • RbcL is an adequate barcode for the taxonomic differentiation of honey varieties. • Honey "pollination" grade is significant for effective genetic analysis. • Melissopalynology-based taxonomy classification correlated with qPCR-HRM results. • Honey "mislabelling" was evidenced by the here-developed molecular analysis. [ABSTRACT FROM AUTHOR]

Highlights • Higher PPO inactivation could be obtained with the synergic effect of UED and temperature. • The effects of thermosonication conditions on HMF content and browning index were opposite. • High temperature-low UED combination must be applied for minimum change in color and ascorbic acid. • Maximum TMA and TP levels obtained at mild temperature (∼50 °C) and UED (∼230 J/g). • Optimum thermosonication parameters were identified for strawberry nectar (59 °C and 455 J/g). Abstract The optimum thermosonication parameters, temperature and ultrasound energy density (UED), determined by using response surface methodology to inactivate polyphenol oxidase (PPO) and protecting the quality parameters, especially color of strawberry nectar. The PPO inactivation was successfully achieved by thermosonication treatment. Increasing of temperature resulted with decreasing of browning index and increasing of hydroxymethyl furfural. High temperature-low UED combination can be applied to obtain minimum change in ΔE∗ and maximum protection of ascorbic acid. Thermosonication at mild temperature (∼50 °C) and UED (∼230 J/g) ensured the maximum levels of total monomeric anthocyanin and total phenolic content. The combination of 59 °C and 455 J/g was the conditions of optimum thermosonication to minimize quality parameters which cause undesirable changes like color degradation in nectar and maximize desirable ones which have beneficial effects on characteristics of nectar or on human health like phenolic content of nectar. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Foraging rate of honeybee on Whangkeumbae was relatively high. • Total sugar content in the nectar of Whangkeumbae was relatively high. • Nine amino acids was significantly different between the cultivars. • Foraging preferences of honeybee depend on sugar and amino acid content. Abstract The foraging preferences of Apis mellifera for flower depend on the content of sugar and amino acid in nectar. To determine the factor in nectar that attracts honeybee in field, we investigated the foraging rate of honeybee, fruit set, relationship between the foraging behavior of honeybee and contents of nectar in different Asian pear cultivars ('Niitaka' and 'Whangkeumbae'), which do not produce pollen. The foraging rate of honeybee on 'Whangkeumbae' was 2 times higher than that on 'Niitaka' and the fruit set of 'Whangkeumbae' was 1.5 times higher than that of 'Niitaka'. 'Whangkeumbae' exhibited 3.7 times higher nectar secretion than 'Niitaka'. The total sugar content in the nectar of 'Whangkeumbae' was 1.1–1.7 times higher than that in the nectar of 'Niitaka', and this difference was significant. Furthermore, the content of glucose, fructose, and sucrose in the nectar of 'Whangkeumbae' was higher than that in the nectar of 'Niitaka'. In particular, the content of sucrose in 'Whangkeumbae' was 1.3–3.2 times higher than that in 'Niitaka'; sucrose is known to be the most preferred sugar by honeybee. Among the 20 amino acids detected in both cultivars, the content of Nine amino acids was significantly different. The content of phenylalanine and glycine (which are preferred by honeybee) in 'Whangkeumbae' was 1.4–2.4 times higher than that in 'Niitaka'. In contrast, the content of asparagine (which is not preferred by honeybee) in 'Niitaka' was 1.1–2.4 times higher than that in 'Whangkeumbae'. Among the sugars in nectar, sucrose exhibited the highest relationship with the number of foraging bees, followed by glucose and fructose. Among the amino acids, phenylalanine presented the highest correlation with the number of foraging bees, followed by glycine and alanine. The results suggest that honeybees prefer 'Whangkeumbae' over 'Niitaka' because of the difference in the amino acid and sugar content in the nectar of pear cultivars. [ABSTRACT FROM AUTHOR]

Abstract For more than six decades, bumblebee death, which mainly occurs in August, has been assumed to be associated with intake of presumed toxic nectar from linden trees (Tilia spp.), a hypothesis which has been sustained by observations of a significant number of dead bumblebees under these trees during their flowering season. Several theories exist in current literature to account for these observations. The nectar has been assumed to contain compound(s) toxic to the bumblebees including the monosaccharide mannose, which cannot be metabolized by bumblebees. The presence of toxic compounds such as the alkaloid nicotine or pesticides of anthropogenic origin has also been indicated. However, none of the above suggested compounds have hitherto been properly characterized from the nectar. In the current paper we report on characterization of the composition of nectar of linden trees, under which a significant number of dead bumblebees were observed. The structure determinations were performed by selective 1D TOCSY NMR and extensive applications of 2D NMR spectroscopy. The nectar of the linden flowers was readily available in significant amounts during the entire period when dead bumblebees were observed under these trees. The nectar only contained non-toxic sugars such as α-glucopyranose, β-glucopyranose, sucrose, fructose and minor amounts of xylose. The nectar did not contain mannose, nor alkaloids or pesticides. Initial toxicity studies using brine shrimp lethality assay showed that the nectar did not exhibit any toxic effects even at concentrations higher than 1 mg/ml dry weight, providing disproving evidence against the assumption of the nectar's toxic character. [ABSTRACT FROM AUTHOR]

Highlights • Two sugar reduction strategies (gradual and stepwise) were compared using grape nectars. • 6–12 year old children evaluated the nectars once a week over a 9-week period. • Sensory and hedonic perception was evaluated. • Gradual sugar reduction caused smaller changes in children’s sensory and hedonic perception. Abstract Excessive sugar consumption has been identified as the main dietary determinants of obesity among children and adolescents. Sugar sweetened beverages are one of the main sources of added sugar in the diet. Therefore, gradual sugar reduction in these products can contribute to decreasing sugar intake and encourage children to slowly develop preference for products with lower sugar concentration. However, specific recommendations on how to implement gradual sugar reduction programs are still lacking. The aim of the present study was to compare two sugar reduction strategies (stepwise vs. gradual) on children’s sensory and hedonic perception of grape nectar. One hundred and seventeen 6–12 years old children participated in a two-part study: a 9-week study and a final liking test at the end of 11 weeks. In the 9-week study, children were divided in two sugar reduction strategies: stepwise and gradual. Children’s sensory and hedonic perception was evaluated using 9-point hedonic scales and check-all-that-apply questions. There were no major differences between the gradual and stepwise reduction groups in children’s sensory and hedonic perception. However, results showed that the gradual reduction strategy led to smaller changes in children’s sensory and hedonic perception than the stepwise strategy. In the final test, children in the stepwise group gave significantly higher liking scores to the samples than those in the gradual sugar reduction strategy. Comparing the overall liking between the first time the children tasted the grape nectars and the final test, a significant difference was observed for the sample with lower sugar content only for the stepwise group, which was higher in the 11th week. Although differences between the sugar reduction strategies were small, the gradual reduction strategy seems to be recommended over the step-wise strategy. [ABSTRACT FROM AUTHOR]

Highlights • The nectary is active during the two days of the anthesis. • Nectar is released mainly by four-celled trichomes. • The sugar content is equivalent in both anthesis days. • Cycles of contraction-expansion of the trichome cells protoplast are present. • Nectar is released through the cell wall and the cuticle of the trichome apical cell. Abstract Cabomba Aubl. is a genus considered as a potential genetic model for studies of early angiosperm evolution, accordingly, it is important to expand the knowledge of it. This paper reports the study of the anatomy and the ultrastructure of the nectary of Cabomba caroliniana Gray using bright-field microscope, scanning and transmission electron microscope in order to understand its secretion mechanism. C. caroliniana has protoginous flowers and the anthesis lasts two days. Nectaries of C. caroliniana are located in two basal lobes or yellow auricles of each white petal. Most nectar is observed in the area above the pronounced auricles. The secretion is released mainly by the four-cellular trichomes or hydropotens present in both nectary epidermis. The cellular ultrastructure indicates that the nectary is active during the two days of the anthesis. This agrees with the fact that in both anthesis days the fertile structures of the flower (first the stigmata and then the anthers) are disposed above the nectaries. The nectar secretion mechanism is discussed in relation to the present knowledge. The results of this study are related to what has been described for other basal angiosperms. [ABSTRACT FROM AUTHOR]

Abstract The instrument NECTAR is located at beam port SR10 of the neutron source FRM II at the Heinz Maier-Leibnitz Zentrum (MLZ). With a pair of moveable uranium plates placed in front of the entrance window of the beam tube, a fission neutron spectrum with a mean energy of 1.9 MeV can be used for neutron imaging applications. Via remote control these plates can be removed and a thermal neutron spectrum (mean energy at 28 meV) gets available for experiments. While the fission neutron spectrum is regularly used, some upgrades of the instrument are necessary to make the thermal neutron spectrum routinely available for user experiments. This includes additional equipment like a new sample stage and a second detector system foreseen to extend the capabilities of NECTAR. The current state of the instrumentation and necessary changes for the future thermal beam option and its usage for standard user experiments will be presented. First measurements were carried out with a temporary flight tube installed and a compact detector (510 mm × 180 mm x 180 mm) for thermal neutrons with a spatial resolution in the range of 100 μm. The feasibility of the thermal beam option could already be verified at an L/D ratio of 240 and a thermal neutron flux of 7.92·106 cm−2 s−1. The thermal neutron beam option adds a pure thermal neutron spectrum – Maxwell spectrum originating from the moderator without alteration by a secondary source or converter – to the energy ranges available for neutron imaging at MLZ instruments. It also offers a unique possibility to combine two quite different neutron energy ranges at a single instrument including their respective advantages. The thermal neutron beam option is funded by BMBF in the frame of research project 05K16VK3. [ABSTRACT FROM AUTHOR]

Abstract Urbanization has negative effects on plant-animal interactions by reducing plant richness and increasing resource limitations. However, it is possible to replant these areas, and plant species can be selected based on the resources they provide, as well as their relationships with animals. I observed several trees of Ceiba pubiflora (Malvaceae, Bombacoideae) to identify the bird species interacting with their flowers in an urban area. This plant may be especially important, as it blossoms during the dry season, when the overall flower availability in the study area is low. It may also be important during a short period of decline in the fleshy fruit supply. Even though C. pubiflora was growing in the city and had a low volume of nectar accumulating in its flowers (mean of 1.73 μl; SD = 1.39 μl), it attracted a variety of birds (25 species belonging to six families), some of which are usually regarded as forest dependent. Nectarivorous birds from the family Trochilidae (hummingbirds, n = 12 species) had the highest percentage of visits (64.08%), especially during periods of relatively high nectar sugar concentration and calorie availability (c. 18% and 1.5 cal., respectively). Hummingbirds primarily acted as nectar thieves but also sometimes as potential flower pollinators. In contrast, several nonnectarivorous birds (frugivore-granivores, frugivore-insectivores and omnivores) acted only as nectar robbers or flower predators. Ceiba pubiflora flowers appear to be an important source of energy for birds in the urban area. The data of this study show that C. pubiflora has utility as management tool to promote and conserve biodiversity in cities. [ABSTRACT FROM AUTHOR]

New Zealand manuka ( Leptospermum scoparium ) and kanuka ( Kunzea ericoides ) honeys contain a unique array of chemical markers useful for chemical fingerprinting. We investigated the presence of 13 potential marker compounds in nectars of the major honey crop species. We confirmed that leptosperin, lepteridine, 2′-methoxyacetophenone, and 2-methoxybenzoic acid are exclusive to manuka nectar whereas lumichrome is unique to kanuka nectar. 3-Phenyllactic acid and 4-hydroxyphenyllactic acid are present in manuka and kanuka nectars. Leptosperin, lepteridine, 3-phenyllactic acid, and 4-hydroxyphenyllactic acid are chemically stable over prolonged storage, but not 2-methoxybenzoic acid and 2′-methoxyacetophenone. Accordingly, leptosperin and lepteridine are definitive chemical markers for authentication of manuka honey. An optimal concentration cut-off was established for the floral source-specific markers: leptosperin (94 mg/kg), lepteridine (2.1 mg/kg), 2′-methoxyacetophenone (2.0 mg/kg) for manuka honey, and lumichrome (4.5 mg/kg) for kanuka honey. The use of leptosperin and lepteridine as fluorescence markers for manuka honey authentication is reinforced. [ABSTRACT FROM AUTHOR]

There is no any doubt about the importance of food fraud control, as it has implications in food safety and in consumer health. Focusing on fruit beverages, some types of adulterations have been detected more frequently, such as substitution with less expensive fruits. A methodology based on attenuated total reflectance Fourier-transform mid-infrared spectroscopy (ATR-FTIR) and multivariate classification was applied to detect whether grape nectars were adulterated by substitution with apple juice or cashew juice. A total of 126 samples were obtained and analyzed. Two strategies were proposed: one-class and multiclass approaches. Soft independent modeling of class analogy (SIMCA), partial least squares discriminant analysis (PLS-DA) and partial least squares density modeling (PLS-DM) were used to build the models. Among them, PLS-DA presented the best performance with a sensitivity and specificity of nearly 100%. The multiclass strategy was preferred if the adulterants to be studied are known because it provides additional information. [ABSTRACT FROM AUTHOR]