Background and Aims Floral deception can range from finely tuned mimicry of specific rewarding plants (Batesian mimicry) to a general resemblance of the rewarding community (generalized food deception). We focused on two species in the deceptive Thelymitra variegata complex (Queen of Sheba orchids) to examine whether pollination is consistent with generalized food deception or with specific mimicry of co-flowering buzz-pollinated tinsel lilies (Calectasia spp.).Methods We assessed (1) overlap in flower colour and scent between orchids, tinsel lilies and other flowers in the rewarding community and (2) pollinator sharing between orchids, tinsel lilies and other species, and (3) quantified orchid reproductive success in relation to abundance of tinsel lilies and other rewarding species.Key Results We found that Thelymitra speciosa matches the flower colour and scent of its co-flowering tinsel lily, Calectasia gracilis, while Thelymitra porphyrosticta partly overlaps with co-flowering Calectasia demarzii in both traits. The orchids and tinsel lilies shared flower visitors, and the only visitor observed to transfer orchid pollen was the bee Anthoglossa plumata (Colletidae), which displayed a behaviour associated with buzz-pollination. This species was also observed to buzz-pollinate tinsel lilies. In T. speciosa, fruit production increased with abundance of both tinsel lilies and other rewarding species with similar flower colour, suggesting a combination of mimicry and magnet effects. However, relationships were driven by a single population. There was no association between rewarding community and reproductive success in T. porphyrosticta.Conclusions The results are partly consistent with mimicry towards the co-flowering tinsel lily for both orchids. Specific mimicry is strongly supported by a close resemblance involving multiple floral traits, and by bee behaviour associated with the buzz-pollinated model. However, this contrasts with the lack of consistent effects of tinsel lily abundance on orchid reproductive success. The findings further suggest that shared floral scent may reinforce visual similarity and highlight that scent may be important in food mimicry systems. Overall, the T. variegata complex offers an interesting system for studying the evolution of mimicry, in particular regarding the contribution of visual and olfactory signals in food mimicry systems.

Mimicry implies that an organism gains fitness by resembling a model species, and one example is rewardless plants that attract pollinators by resembling co-flowering species that provide rewards. While trait matching between mimic and model has been characterised in many cases of putative floral mimicry, few have demonstrated that resemblance is adaptive and dependent on model presence. Sun orchids (Thelymitra) are believed to mimic the flowers of buzz-pollinated rewarding plants by displaying false anthers. To test the adaptive value of the false anthers, we examined whether the fruit production of Thelymitra crinita and Thelymitra macrophylla was reduced when anthers were experimentally removed or obscured, and whether the reduction was stronger when putative model plants were abundant. We also assessed the visual flower similarity of both orchids and their putative model plants according to bee colour perception and identified shared pollinators and whether their behaviour on T. crinita was similar to that on buzz-pollinated model plants. Fruit production of both sun orchids was strongly reduced (60%-71%) by removal or painting of false anthers but was not affected by the abundance of model plants. Sun orchid flowers closely matched flower colour of co-flowering pollen-rewarding species, and T. crinita shared pollinators with the rewarding species. Visiting bees attempted to buzz and manipulate the false anther, with a behaviour similar to that observed on model plants. The experimental results demonstrate that the false anther is an important adaptation to pollination in sun orchids. Striking visual flower similarity and shared pollinators between orchids and models suggest that sun orchids are pollinated by bees that mistake orchids for buzz-pollinated rewarding plants. The adaptive value of the false anther did not depend on model plant abundance in the local population, indicating that the relevant spatial scale is larger or that the effects of the model species are weak in comparison to the effects of other rewarding species, that is that magnet effects of nectar-rewarding species are dominating. False anthers are widespread in the genus Thelymitra, and this 'mimicry trait' seems to represent an evolutionary novelty that offers unique opportunities to explore adaptations to pollination in deceptive plants.Read the free for this article on the Journal blog.

Global warming is one of the biggest threats to global biodiversity causing not only changes in the patterns of precipitation and temperature but also disturbing ecological interactions. The aim of our study was to forecast the effect of climate change on the distribution of food-deceptive orchid species whose pollination strategy relies on a strict association with pollinators and co-occurring rewarding Faboideae plants. We used the ecological niche modeling approach to evaluate future overlap of the suitable niches of studied orchid species with the predicted distribution of their ecological partners. Models were made based on two different global circulation models (FIO, CNRM). CNRM projections predict expansion of orchids' geographical range. In contrast, FIO prediction is less optimistic, forecasting species range contraction. The studied Faboideae species showed different responses to predicted global warming with no consistent patterns in how their suitable niches might change. Most climate change projections and scenarios of the future modifications of temperature and precipitation patterns do not predict significant loss of suitable niches of Trichocolletes bees (Colletidae) pollinating Diuris species. However, global warming has the potential to disrupt interactions between the studied orchids and their co-occurring pea plants by altering the overlap of their geographical ranges which can further disturb pollination success. CNRM projections predict an overall loss of Faboideae within the potential geographical range of Diuris brumalis. Conversely, FIO projections suggest a less extensive predicted divergence. Our simulations offer suggestions for conservation strategies of orchids and potentially for other species that have a similar pollination strategy. The areas indicated here as suitable in the future for the occurrence of all ecological partners can be important climate refugia to consider in local conservation plans. The approach used in our study can serve as a model for understanding the potential effects of climate change on the strength of the pollination system via food deception.

Biological invasions threaten global biodiversity, altering landscapes, ecosystems, and mutualistic relationships like pollination. Orchids are one of the most threatened plant families, yet the impact of invasive bees on their reproduction remains poorly understood. We conduct a global literature survey on the incidence of invasive honeybees (Apis mellifera) on orchid pollination, followed by a study case on Australian orchids. Our literature survey shows that Apis mellifera is the primary alien bee visiting orchids worldwide. However, in most cases, introduced honeybees do not deposit orchid pollen. We also test the extent to which introduced honeybees affect orchid pollination using Diuris brumalis and D. magnifica. Diuris brumalis shows higher fruit set and pollination in habitats with both native and invasive bees compared to habitats with only introduced bees. Male and female reproductive success in D. magnifica increases with native bee abundance, while conversely pollinator efficiency decreases with honeybee abundance and rises with habitat size. Our results suggest that introduced honeybees are likely involved in pollen removal but do not effectively deposit orchid pollen, acting as pollen wasters. However, Apis mellifera may still contribute to pollination of Diuris where native bees no longer exist. Given the global occurrence of introduced honeybees, we warn that certain orchids may suffer from pollen depletion by these invaders, especially in altered habitats with compromised pollination communities.

Background: To attract their pollinators non-rewarding orchids rely on various deception strategies that range from generalised food deception to floral mimicry of a specific model (Batesian mimicry). Aims: We evaluated whether the deceptive orchid Anacamptis morio may represent an initial step in the evolutionary trajectory from generalised food deception to Batesian mimicry by resembling the rewarding Polygala nicaeensis, a species with purple flowers very similar to those of A. morio. Methods: We assessed the pollination success of A. morio in relation to co-flowering rewarding species. Then, we estimated male and female reproductive success of A. morio depending on the presence of and similarity to the putative model P. nicaeensis. Results: The pollination success of A. morio covaried with that of P. nicaeensis and its pollination efficiency was higher when the two species co-occurred. However, we did not find supporting evidence that A. morio mimicked its potential rewarding model. We also found that the orchids with stronger colour reflectance exhibited greater pollination success, according to a scenario of ecological facilitation rather than adaptive mimicry. Conclusion: Co-flowering rewarding species with a colour similar to the orchid may enhance the specific pollinator abundance and condition their foraging preference, hence producing a positive effect on the reproductive success of A. morio.

Biological invasion is one of the leading threats to global biodiversity. Invasive species can change the structure and dynamics of landscapes, communities, and ecosystems, and even alter mutualistic relationships across species such as pollination. Orchids are one of the most threatened plant families globally and known to have established specialised pollination mechanism to reproduce, yet the impact of invasive bees on orchid reproduction has not been comprehensively assessed. We conduct a literature survey to document global patterns of the impact of invasive honeybees on orchids’ pollination. We then present a study case from Australian orchids, testing the extent to which introduced honeybees can successfully pollinate orchids across different degrees of habitat alteration, using Diuris brumalis and D. magnifica (Orchidaceae). Globally, Apis mellifera is the principal alien bee potentially involved in orchid pollination. We show that pollinator efficiency and fruit set in D. brumalis is higher in wild habitats in which both native bees and invasive honeybees are present, relative to altered habitat with introduced honeybees only. Pollen removal and fruit set of D. magnifica rise with native bees’ abundance whilst pollinator efficiency decreases with honeybee abundance and increases with habitat size. Complementarily to our findings, our literature survey suggests that the presence of introduced honeybees adversely impacts orchid pollination, likely via inefficient pollen transfer. Given the worldwide occurrence of introduced honeybees, we warn that some orchids may be negatively impacted by these alien pollinators, especially in altered and highly fragmented habitats where natural pollination networks are compromised.

Trichocolletes orientalis is an Australian solitary, ground-nesting bee, reported to have some unusual aspects to its nesting biology. Prime among these, and a focus for the present study, is the production of copious amounts of oil by post-feeding pre-defaecating larvae. To better understand the mechanism of oil production, we examined the bee’s floral resources and larval provisions and compared the fatty acid profiles of the provision and larval oil exudate using gas chromatography. The study population was monolectic on the legume Hardenbergia comptoniana . Unusually for Neopasiphaeinae, larval provisions were liquid but contained no obvious free oil. Differences in the fatty acid composition of the provision and larval oil lead us to conclude that larvae must secrete the oil. Fully fed larvae prevented from curling produced a yellowish, non-oily liquid from the anus. The Malpighian tubules are implicated in the production of this liquid and perhaps the oil (which has not been reported for any other bee species). While likely preventing water loss from resting larvae, the oil contains some fatty acids with known antimicrobial and antifungal properties and might protect the larvae from pathogens. Additionally, we provide a complete life cycle calendar for the bee.

Little is known about the pollination mechanisms of species belonging to the genus Vanilla (Orchidaceae). Both autonomous self-pollination and animal-mediated pollination mechanisms seem to exist amongst the Vanilla species, yet few studies provided real evidence on pollination events. The aim of this study was to better understand the pollination mechanism of Vanilla hartii. Four V. hartii populations were selected within our study area in southern Costa Rica to observe pollination events and identify the natural pollinators of this Neotropical Vanilla species. We tested for nectar presence, analysed nectar composition, and examined floral fragrances. Furthermore, we identified floral visitors and documented their behaviour, quantified fruit set during two years, and compared morphological traits of flowers and their visitors. Sampled flowers contained 1.85 +/- 1.07 mu L nectar that averaged 34.79% sugar, dominated by sucrose. We observed orchid bees belonging to the genus Euglossa entering the tube formed by the labellum to search for nectar, indicated by their extended proboscis and prolonged visits, some of which exited the labellar tube with pollen masses attached to their scutellum. Combining our behavioural and phytochemical data, we demonstrate the presence of a nectar-rewarding pollination mechanism in the genus Vanilla that shows a higher natural fruit set compared to deceptive Vanilla species. An overview of the pollination mechanisms known so far provides insights into the potential evolution of reproductive strategies within this commercially important orchid genus.

Flowers have many traits to appeal to pollinators, including ultraviolet (UV) absorbing markings, which are well-known for attracting bees at close proximity (e.g., <1 m). While striking UV signals have been thought to attract pollinators also from far away, if these signals impact the plant pollinia removal over distance remains unknown. Here, we report the case of the Australian orchid Diuris brumalis, a nonrewarding species, pollinated by bees via mimicry of the rewarding pea plant Daviesia decurrens. When distant from the pea plant, Diuris was hypothesized to enhance pollinator attraction by exaggeratedly mimicking the floral ultraviolet (UV) reflecting patterns of its model. By experimentally modulating floral UV reflectance with a UV screening solution, we quantified the orchid pollinia removal at a variable distance from the model pea plants. We demonstrate that the deceptive orchid Diuris attracts bee pollinators by emphasizing the visual stimuli, which mimic the floral UV signaling of the rewarding model Daviesia. Moreover, the exaggerated UV reflectance of Diuris flowers impacted pollinators' visitation at an optimal distance from Da. decurrens, and the effect decreased when orchids were too close or too far away from the model. Our findings support the hypothesis that salient UV flower signaling plays a functional role in visual floral mimicry, likely exploiting perceptual gaps in bee neural coding, and mediates the plant pollinia removal at much greater spatial scales than previously expected. The ruse works most effectively at an optimal distance of several meters revealing the importance of salient visual stimuli when mimicry is imperfect.

Orchid seeds are predominantly wind-dispersed, often developed within dry, dehiscent fruits that typically release millions of dust-like seeds into the air. Animal-mediated seed dispersal is a lesser-known phenomenon in the family and predominantly occurs in groups belonging to early-diverging lineages bearing indehiscent, fleshy fruits with hard, rounded, dark seeds. In this review, we explore the evolutionary trends of seed dispersal mechanisms in Orchidaceae, focusing on the pantropical genus Vanilla. Notably, certain Neotropical species of Vanilla produce vanillin-aromatic compounds synthesized naturally in their fruits, which plays a pivotal role in seed dispersal. Ectozoochory occurs in dry, dehiscent fruits, whose seeds are dispersed by (i) male euglossine bees collecting the fruit’s vanillin aromatic compounds and (ii) female stingless bees collecting the fruit’s mesocarp. Endozoochory occurs in (iii) highly nutritious, indehiscent fruits consumed by terrestrial mammals or (iv) fleshy, dehiscent fruits whose mesocarp is consumed by arboreal mammals. Wind dispersal appears to be a derived state in Orchidaceae and, given its predominance, a trait likely associated with enhanced speciation rates. Zoochory primarily occurs in groups derived from early-diverging lineages; occasional reversions suggest a link between dispersal mode and fruit and seed traits. Interestingly, fruit dehiscence and fleshiness in Vanilla lack phylogenetic signal despite their role in determining dispersal modes, suggesting potential environmental adaptability.

Comparison and quantification of multiple pre- and post-pollination barriers to interspecific hybridization are important to understand the factors promoting reproductive isolation. Such isolating factors have been studied recently in many flowering plant species which seek after the general roles and relative strengths of different pre- and post-pollination barriers. In this study, we quantified six isolating factors (ecogeographic isolation, phenological isolation, pollinator isolation, pollinia-pistil interactions, fruit production, and seed development) that could possibly be acting as reproductive barriers at different stages among three sympatric Habenaria species (H. limprichtii, H. davidii, and H. delavayi). These three species overlap geographically but occupy different microhabitats varying in soil water content. They were isolated through pollinator interactions both ethologically (pollinator preference) and mechanically (pollinia attachment site), but to a variable degree for different species pairs. Interspecific crosses between H. limprichtii and H. davidii result in high fruit set, and embryo development suggested weak post-pollination barriers, whereas bidirectional crosses of H. delavayi with either of the other two species fail to produce fruits. Our results revealed that pollinators were the most important isolating barrier including both ethological and mechanical mechanisms, to maintain the boundaries among these three sympatric Habenaria species. Our study also highlights the importance of a combination of pre-and post-pollination barriers for species co-existence in Orchidaceae.

Natural pollination of Vanilla species remains poorly understood. Our research aimed at better understanding the pollinator attraction mechanism of the Neotropical species Vanilla pompona. Based on our results, we hypothesize that the identified pollinator Eulaema cingulata is attracted via a dual mechanism combining floral fragrance rewards and food deception. Abstract in Spanish is available with online material.

Natural pollination of species remains poorly understood. Our research aimed at better understanding the pollinator attraction mechanism of the Neotropical species . Based on our results, we hypothesize that the identified pollinator is attracted via a dual mechanism combining floral fragrance rewards and food deception. Abstract in Spanish is available with online material. La polinización bajo condiciones naturales de las especies de   sigue siendo poco conocida. Nuestra investigación tiene como objetivo comprender mejor el mecanismo de atracción de polinizadores de la especie Neotropical . Con base en los resultados obtenidos, planteamos la hipótesis de que el polinizador, identificado como  , es atraído a través de un mecanismo doble que combina la recompensa por medio de fragancias florales y el engaño alimenticio.

Bee venom (BV) is the most valuable product harvested from honeybees ($30 - $300 USD per gram) but marginally produced in apiculture. Though widely studied and used in alternative medicine, recent efforts in BV research have focused on its therapeutic and cosmetic applications, for the treatment of degenerative and infectious diseases. The protein and peptide composition of BV is integral to its bioactivity, yet little research has investigated the ecological factors influencing the qualitative and quantitative variations in the BV composition. Bee venom from Apis mellifera ligustica (Apidae), collected over one flowering season of Corymbia calophylla (Myrtaceae; marri) was characterized to test if the protein composition and amount of BV variation between sites is influenced by i) ecological factors (temperature, relative humidity, flowering index and stage, nectar production); ii) management (nutritional supply and movement of hives); and/or iii) behavioural factors. BV samples from 25 hives across a 200 km-latitudinal range in Southwestern Australia were collected using stimulatory devices. We studied the protein composition of BV by mass spectrometry, using a bottom-up proteomics approach. Peptide identification utilised sequence homology to the A. mellifera reference genome, assembling a BV peptide profile representative of 99 proteins, including a number of previously uncharacterised BV proteins. Among ecological factors, BV weight and protein diversity varied by temperature and marri flowering stage but not by index, this latter suggesting that inter and intra-year flowering index should be further explored to better appreciate this influence. Site influenced BV protein diversity and weight difference in two sites. Bee behavioural response to the stimulator device impacted both the protein profile and weight, whereas management factors did not. Continued research using a combination of proteomics, and bio-ecological approaches is recommended to further understand causes of BV variation in order to standardise and improve the harvest practice and product quality attributes.

Background and Aims Colour pattern is a key cue of bee attraction selectively driving the appeal of pollinators. It comprises the main colour of the flower with extra fine patterns, indicating a reward focal point such as nectar, nectaries, pollen. stamens and floral guides. Such advertising of floral traits guides visitation by the insects, ensuring precision in pollen gathering and deposition. The study, focused in the Southwest Australian Floristic Region, aimed to spot bee colour patterns that are usual and unusual, missing, accomplished by mimicry of pollen and anthers, and overlapping between mimic-model species in floral mimicry cases. Methods Floral colour patterns were examined by false colour photography in 55 flower species of multiple highly diverse natural plant communities in south-west Australia. False colour photography is a method to transform a UV photograph and a colour photograph into a false colour photograph based on the trichromatic vision of bees. This method is particularly effective for rapid screening of large numbers of flowers for the presence of fine-scale bee-sensitive structures and surface roughness that are not detectable using standard spectrophotometry. Key Results Bee- and bird-pollinated flowers showed the expected but also some remarkable and unusual previously undetected floral colour pattern syndromes. Typical colour patterns include cases of pollen and flower mimicry and UV-absorbing targets. Among the atypical floral colour patterns are unusual white and UV-reflecting flowers of bee-pollinated plants, bicoloured floral guides, consistently occurring in Fabaceae spp., and flowers displaying a selective attractiveness to birds only. In the orchid genera (Diuris and Thelymitra) that employ floral mimicry of model species, we revealed a surprising mimicry phenomenon of anthers mimicked in turn by model species. Conclusion The study demonstrates the applicability of 'bee view' colour imaging for deciphering pollinator cues in a biodiverse flora with potential to be applied to other eco regions. The technique provides an exciting opportunity for indexing floral traits on a biome scale to establish pollination drivers of ecological and evolutionary relevance.

Rewarding plants can enhance the pollination success of co-occurring plants pollinated by food mimicry. However, it is not always possible to readily discern between the effect of model and magnet species. Here, we tested for mimicry of co-occurring Fabaceae by the rewardless Diuris magnifica (Orchidaceae) and whether the number of flowers of Fabaceae, habitat remnant size and frequency of conspecifics, influenced the pollination success of D. magnifica. Trichocolletes bees were the primary pollinators of D. magnifica, on which they displayed similar behaviour as seen when feeding on Fabaceae. Quantification of spectral reflectance suggested that flowers of Bossiaea eriocarpa,Daviesia divaricata and Jacksonia sternbergiana may represent models for D. magnifica, whereas Hardenbergia comptoniana strongly differed in colour. Orchid pollination success was not directly affected by the number of model flowers, but the pollination rate was enhanced by increased numbers of Hardenbergia flowers. Pollination success of the orchid decreased with higher density of conspecifics, but did not exhibit a significant relationship with Trichocolletes occurrence, possibly because of the contribution of sub-optimal pollinator species. Fruit set of the orchid was greater in larger habitat remnants. Overall, pollination success of D. magnifica is affected by ecological factors related to the effectiveness of mimicry, numbers of co-flowering plants and anthropogenic landscape alteration.

Despite their diversity and the potential for specialized pollination systems, Australian Fabaceae have received little attention in pollination studies. In the Southwest Australian Floristic Region (SWAFR), a recognized biodiversity hotspot, co-occurring and abundant species of Faboideae exhibit a range of floral colours and forms, suggestive of adaptation to different groups of pollinators. For four communities of Fabaceae in the SWAFR we investigated whether co-occurring species overlap in pollinator genera, whether these pollinators show differences in behaviour on the pea flower and whether variations in stamen length and nectar composition among species are associated with different pollinator types. Species of Fabaceae were visited by one to four genera of native bees, suggesting varying levels of ecological specialisation. In Fabaceae with more specialized interactions, co-occurring species showed marked differences in the bee genera attracted. Unexpectedly, some Fabaceae frequently attracted beetles, which may play an important role in their pollination. There was no evidence for an association between stamen length or nectar composition and the type of pollinator. The introduced honeybee, visited all studied species of Fabaceae, suggesting that they may act both as a pollinator and a potential competitor with native pollinators.

Soil contamination by potentially toxic trace elements (PTEs) such as Cadmium (Cd), is a major environmental concern because of its potential implications to human health. Cacao-based products have been identified as food sources with relatively high Cd contents. Here, we assessed Cd concentrations of cacao-growing soils in four major agricultural regions with contrasting climates in Peru, one of the main exporters of cacao products worldwide. At each study site (n = 40) a broad range of potential factors affecting Cd concentration in soils, i.e., site, soil and management, were evaluated. Concentrations of Cd ranged between 1.1–3.2 mg kg−1. Mean values per region were below 2.7 mg kg−1, usually established as upper-limit for non-polluted soils. Cadmium concentrations were significantly (p < 0.001) higher in sites at higher elevations and in a temperate, drier climate. Cadmium correlated positively with pH (r = 0.57; p < 0.05) and was higher (p < 0.001) in alluvial sediments and Leptosols. Management factors (cacao variety, cultivation year, management practices) and agroecology did not affect Cd concentrations directly. Overall, this study highlights the importance of considering a broad range of both natural and anthropogenic factors to evaluate Cd concentrations in cacao-growing soils and contribute to effective and sustainable cacao production by improving land management and planning.

Sampling nectar from forest canopies is logistically challenging as it requires physical access to the canopy to a height greater than that can be achieved by hand. The most common solutions comprise the use of cherry pickers, cranes or tree climbers. These techniques are generally expensive, logistically complex, and often involve additional safety risks and specialized technicians to use the equipment/machinery. In addition, access is required up to the tree for cherry pickers and cranes, and tree climbers are often unable to reach the outermost branches. Here, we propose a simple approach based on a special, easy to assemble tool, to sample tree flowers for subsequent nectar extraction, to avoid climbing and cumbersome/expensive equipment. Conducting a study on nectar production of Eucalypt trees (Myrtaceae) in southwest Australia, we conceived a practical ground‐based tool formed by an extendible pole with an adapted container at the end for covering the tree inflorescence with organza and plastic (polyethylene) bags. We experimented with the tool on dozens of trees of each of the co‐occurring species Eucalyptus marginata and Corymbia calophylla, successfully completing the following operational manoeuvres: bagging the inflorescence with an organza bag prior to the nectar collection, then bagging the inflorescence and organza bags with plastic bags if necessary, and cutting the bagged inflorescences from the branch for subsequent nectar extraction. We present the instructions for assembling the tool and we detail the sequence for bagging and sampling flowers from canopy trees, including time‐saving tips. This approach allows efficient sampling of tree flowers for subsequent nectar extraction. To effectively handle the tool while covering the inflorescence, the maximum sample collection height is approximately 10 m. Overall, the tool helps to address limitations related to sampling nectar from medium‐height trees such as costs, risks and time factors. Beyond tree flowers, the tool can be used for sampling flowers of epiphytic and climbing plants, and it could also be used to test for autogamy in flowering trees.