Plant Reproductive Success Research Articles

The effect of global warming on the Australian endemic orchid Cryptostylis leptochila and its pollinator.

Ecological stability together with the suitability of abiotic conditions are crucial for long-term survival of any organism and the maintenance of biodiversity and self-sustainable ecosystems relies on species interactions. By influencing resource availability plants affect the composition of plant communities and ultimately ecosystem functioning. Plant-animal interactions are very complex and include a variety of exploitative and mutualistic relationships. One of the most important mutualistic interactions is that between plants and their pollinators. Coevolution generates clustered links between plants and their pollen vectors, but the pollination and reproductive success of plants is reduced by increase in the specialization of plant-animal interactions. One of the most specialized types of pollination is sexual deception, which occurs almost exclusively in Orchidaceae. In this form of mimicry, male insects are attracted to orchid flowers by chemical compounds that resemble insect female sex pheromones and pollinate the flowers during attempted copulations. These interactions are often species-specific with each species of orchid attracting only males of one or very few closely related species of insects. For sexually deceptive orchids the presence of a particular pollen vector is crucial for reproductive success and any reduction in pollinator availability constitutes a threat to the orchid. Because global warming is rapidly becoming the greatest threat to all organisms by re-shaping the geographical ranges of plants, animals and fungi, this paper focuses on predicting the effect of global warming on Cryptostylis leptochila, a terrestrial endemic in eastern Australia that is pollinated exclusively via pseudo copulation with Lissopimpla excelsa. As a species with a single pollinator this orchid is a perfect model for studies on the effect of global warming on plants and their pollen vectors. According to our predictions, global warming will cause a significant loss of suitable niches for C. leptochila. The potential range of this orchid will be 36%-75% smaller than currently and as a result the Eastern Highlands will become unsuitable for C. leptochila. On the other hand, some new niches will become available for this species in Tasmania. Simultaneously, climate change will result in a substantial expansion of niches suitable for the pollinator (44-82%). Currently ca. 71% of the geographical range of the orchid is also suitable for L. excelsa, therefore, almost 30% of the areas occupied by C. leptochila already lack the pollen vector. The predicted availability of the pollen vector increased under three of the climate change scenarios analysed. The predicted habitat loss is a serious threat to this orchid even with the potential colonization of Tasmania by this plant. In the reduced range of C. leptochila the pollen vector will also be present assuring fruit set in populations of this orchid. The genetic pool of the populations in New South Wales and Queensland will probably be lost.

Altered regulation of flowering expands growth ranges and maximizes yields in major crops.

Flowering time influences reproductive success in plants and has a significant impact on yield in grain crops. Flowering time is regulated by a variety of environmental factors, with daylength often playing an important role. Crops can be categorized into different types according to their photoperiod requirements for flowering. For instance, long-day crops include wheat (Triticum aestivum), barley (Hordeum vulgare), and pea (Pisum sativum), while short-day crops include rice (Oryza sativa), soybean (Glycine max), and maize (Zea mays). Understanding the molecular regulation of flowering and genotypic variation therein is important for molecular breeding and crop improvement. This paper reviews the regulation of flowering in different crop species with a particular focus on how photoperiod-related genes facilitate adaptation to local environments.

The circadian clock controls temporal and spatial patterns of floral development in sunflower.

Biological rhythms are ubiquitous. They can be generated by circadian oscillators, which produce daily rhythms in physiology and behavior, as well as by developmental oscillators such as the segmentation clock, which periodically produces modular developmental units. Here, we show that the circadian clock controls the timing of late-stage floret development, or anthesis, in domesticated sunflowers. In these plants, up to thousands of individual florets are tightly packed onto a capitulum disk. While early floret development occurs continuously across capitula to generate iconic spiral phyllotaxy, during anthesis floret development occurs in discrete ring-like pseudowhorls with up to hundreds of florets undergoing simultaneous maturation. We demonstrate circadian regulation of floral organ growth and show that the effects of light on this process are time-of-day dependent. Delays in the phase of floral anthesis delay morning visits by pollinators, while disruption of circadian rhythms in floral organ development causes loss of pseudowhorl formation and large reductions in pollinator visits. We therefore show that the sunflower circadian clock acts in concert with environmental response pathways to tightly synchronize the anthesis of hundreds of florets each day, generating spatial patterns on the developing capitulum disk. This coordinated mass release of floral rewards at predictable times of day likely promotes pollinator visits and plant reproductive success.

Silencing of a Pectin Acetylesterase (PAE) Gene Highly Expressed in Tobacco Pistils Negatively Affects Pollen Tube Growth.

Successful plant reproduction and fruit formation depend on adequate pollen and pistil development, and pollen-pistil interactions. In Nicotiana tabacum, pollen tubes grow through the intercellular spaces of pistil-specialized tissues, stigmatic secretory zone, and stylar transmitting tissue (STT). These intercellular spaces are supposed to be formed by the modulation of cell wall pectin esterification. Previously we have identified a gene preferentially expressed in pistils encoding a putative pectin acetylesterase (PAE), named NtPAE1. Here, we characterized the NtPAE1 gene and performed genome-wide and phylogenetic analyses of PAEs. We identified 30 PAE sequences in the N. tabacum genome, distributed in four clades. The expression of NtPAE1 was assessed by RT-qPCR and in situ hybridization. We confirmed NtPAE1 preferential expression in stigmas/styles and ovaries and demonstrated its high expression in the STT. Structural predictions and comparisons between NtPAE1 and functional enzymes validated its identity as a PAE. Transgenic plants were produced, overexpressing and silencing the NtPAE1 gene. Overexpressed plants displayed smaller flowers while silencing plants exhibited collapsed pollen grains, which hardly germinate. NtPAE1 silencing plants do not produce fruits, due to impaired pollen tube growth in their STTs. Thus, NtPAE1 is an essential enzyme regulating pectin modifications in flowers and, ultimately, in plant reproduction.

Cross-Talk between Transcriptome Analysis and Dynamic Changes of Carbohydrates Identifies Stage-Specific Genes during the Flower Bud Differentiation Process of Chinese Cherry (Prunus pseudocerasus L.)

Flower bud differentiation is crucial to reproductive success in plants. In the present study, RNA-Seq and nutrients quantification were used to identify the stage-specific genes for flower bud differentiation with buds which characterize the marked change during flower bud formation from a widely grown Chinese cherry (Prunus pseudocerasus L.) cultivar 'Manaohong'. A KEGG enrichment analysis revealed that the sugar metabolism pathways dynamically changed. The gradually decreasing trend in the contents of total sugar, soluble sugar and protein implies that the differentiation was an energy-consuming process. Changes in the contents of D-glucose and sorbitol were conformed with the gene expression trends of bglX and SORD, respectively, which at least partially reflects a key role of the two substances in the transition from physiological to morphological differentiation. Further, the WRKY and SBP families were also significantly differentially expressed during the vegetative-to-reproductive transition. In addition, floral meristem identity genes, e.g., AP1, AP3, PI, AGL6, SEP1, LFY, and UFO demonstrate involvement in the specification of the petal and stamen primordia, and FPF1 might promote the onset of morphological differentiation. Conclusively, the available evidence justifies the involvement of sugar metabolism in the flower bud differentiation of Chinese cherry, and the uncovered candidate genes are beneficial to further elucidate flower bud differentiation in cherries.

Fine‐scale temporal dynamics of flower visitors sheds light on insect‐assemblage overlap between sexes in a dioecious Ecuadorian palm

AbstractDioecious plants generally display sexual dimorphism in male and female floral traits, potentially attracting slightly different pollinator communities. The sharing of common floral visitors between male and female flowers and their timing of visits to both sexes is of critical importance to ensure plant's reproductive success. Palm inflorescences are visited by abundant and diverse insect communities, yet the temporal patterns of insect visits on both sexes remain poorly known. We characterized the composition of a community of flower‐visiting arthropods associated with the dioecious ivory palm (Phytelephas aequatorialis, Spruce) in a pre‐montane forest of Ecuador. We monitored the temporal variations in insect visits along the flowering of 12 inflorescences (eight female and four male) using interception traps recovered every 4 h. We report 59 morphospecies in the arthropod community, dominated by three beetle families: Staphylinidae, Nitidulidae, and Curculionidae. Male inflorescences were more abundantly visited than female, but visitors of the later were taxonomically more diverse. Among the 16 pollinator candidates identified, nine visited both inflorescence sexes synchronously at dusk /night whereas the others did so asynchronously during the day. Our study provides new insights into the pollination mechanism ofP. aequatorialis.We found evidence of differential pollinator attraction between floral sexes, which may be explained by the sexual dimorphism of both flowers. Synchronicity in dusk/night visits of both inflorescence sexes suggests a sexual synchronization of the signal used to attract pollinators.Abstract in Spainsh is available with online material

Stamen curvature and temporal flower closure assure reproductive success in an early-spring-flowering perennial in the cold desert of Middle Asia.

Floral organ movements that ensure autonomous selfing are likely to occur in species that grow in habitats with pollinator scarcity and/or an unpredictable environment. Stamen curvature and temporal flower closure are two important floral behaviors that can influence plant pollination mode and reproductive success. However, both behaviors are rarely reported within a species, and little is known about how these two movements of floral organs ensure reproductive success in an unpredictable early spring environment with few pollinators. The aim of this study was to assess whether stamen curvature and temporal flower closure ensure successful reproduction of Leontice incerta in its cold desert habitat. Flowering phenology, floral traits, stamen curvature patterns and flower visitors were surveyed. The breeding system, capacity and timing for autonomous selfing were estimated by pollination manipulations. The timing of floral opening and closure, and benefits of temporal flower closure were determined. We found that flowering of L. incerta began in late March to early April in two populations in two years, and the yellow flowers had neither nectar nor scent. Floral visitation occurred very rarely, but bees (Colletes sp.) were potential pollinators. Fruit and seed set of open and bagged flowers did not differ significantly from that of self-pollinated or cross-pollinated flowers. However, removal of stamens significantly decreased seed set. Self-pollination occurs when the stamens curve and anthers touch the stigma autonomously, suggesting autonomous selfing assurance of seed production in this self-compatible species. Both fruit and seed set of flowers that were prevented from closing were significantly lower than those of control flowers and closed flowers treated with simulated rain treatment. Therefore, stamen curvature and temporal floral closure can ensure successful sexual reproduction of L. incerta in early spring in the cold desert, where lack of pollinators otherwise may lead to pollination failure.

Reduced seed set under water deficit is driven mainly by reduced flower numbers and not by changes in flower visitations and pollination

Abstract Water deficit can alter floral traits with cascading effects on flower‐visitor interactions and plant fitness. Water stress induction can diminish productivity, directly resulting in lower flower production and consequently seed set. Changes in floral traits, such as floral scent or reward amount, may in turn alter pollinator visitations and behaviour and consequently can reduce pollination services resulting in lower reproduction output. However, the relative contribution of this indirect in comparison to the direct effects to changes in seed set are not fully understood. We manipulated water availability using rain‐out shelters in a field experiment and measured effects on floral scent bouquet, morphology, phenology, flower‐visitor interactions, pollination and seed set. Plant individuals of Sinapis arvensis (Brassicaceae) were randomly assigned to one of three treatments: mean precipitation (=control), reduced mean precipitation or drought period treatment. Our results show that decreasing water availability lowers the number of flowers and seed set. This indicates a direct link between water stress and seed set, as seed mass increases with increasing flower number. The indirect link of water stress via floral traits, pollinator visits and pollination has weaker effects on seed set. However, floral traits remain relatively stable under decreased water availability, whereas plant growth and flower abundance decrease, potentially in order to allow investment in more resources in fewer flowers to maintain pollination success. Thus, plants are able to compensate for water stress and can maintain floral trait expression, such as a stable scent emission and bouquet, to retain pollinator attraction. These findings indicate that the direct link from water stress to seed set has a stronger impact on plants reproductive success than the indirect link through altered floral trait expression and pollinator visits in a generalist plant species. Read the free Plain Language Summary for this article on the Journal blog.

AcBBX5, a B-box transcription factor from pineapple, regulates flowering time and floral organ development in plants.

Flowering is an important factor to ensure the success of plant reproduction, and reasonable flowering time is crucial to the crop yield. BBX transcription factors can regulate several growth and development processes. However, there is little research on whether BBX is involved in flower formation and floral organ development of pineapple. In this study, AcBBX5, a BBX family gene with two conserved B-box domains, was identified from pineapple. Subcellular localization analysis showed that AcBBX5 was located in the nucleus. Transactivation analysis indicated that AcBBX5 had no significant toxic effects on the yeast system and presented transcriptional activation activity in yeast. Overexpression of AcBBX5 delayed flowering time and enlarged flower morphology in Arabidopsis. Meanwhile, the expression levels of AtFT, AtSOC1, AtFUL and AtSEP3 were decreased, and the transcription levels of AtFLC and AtSVP were increased in AcBBX5-overexpressing Arabidopsis, which might lead to delayed flowering of transgenic plants. Furthermore, transcriptome data and QRT-PCR results showed that AcBBX5 was expressed in all floral organs, with the high expression levels in stamens, ovaries and petals. Yeast one-hybrid and dual luciferase assay results showed that AcBBX5 bound to AcFT promoter and inhibited AcFT gene expression. In conclusion, AcBBX5 was involved in flower bud differentiation and floral organ development, which provides an important reference for studying the functions of BBX and the molecular regulation of flower.

Ineffectiveness of ants in protecting two sympatric myrmecophilous plants against endophytic beetles

AbstractExtrafloral nectarized plants attract ants, which may protect them against herbivory and increase plant fruit set production. In some cases, however, ants are ineffective against herbivores. Such events occur, for instance, when herbivores present adaptations to avoid ant predation. Thus, the outputs of these interactions depend on factors such as ant identity, plant phenology and herbivore features. Here, we investigated the endophytic florivorous beetles' impact on the reproductive success of their host plants, two sympatric Banisteriopsis (Malpighiaceae) species, depending on the action of extrafloral nectaries (EFNs) visiting ants. We experimentally manipulated the presence of ants and herbivores on B. malifolia and B. laevifolia species during their reproductive period to test the effectiveness of ants‐EFNs mutualism on plant fruit set production. We performed treatments where three similar inflorescences were selected to be (I) control branch, with no manipulations, (II) beetle‐free branch, isolated with textile cover and (III) ant‐free branch, isolated at the base with atoxic wax. We hypothesized that endophytic herbivores have a negative impact on the plant reproductive success because they escape the action of ants (biotic defences). As a result, we observed (i) that florivorous Anthonomus beetles have a negative impact on Banisteriopsis reproductive success; (ii) ants fail in protecting plants against floral endophytic beetles; and (iii) most of the results were species‐specific. Our results indicate that these systems present very conditional outcomes that depend on the intrinsic factors of each plant species.

Simulated climate warming decreases fruit number but increases seed mass.

Climate warming is changing plant sexual reproduction, having consequences for species distribution and community dynamics. However, the magnitude and direction of plant reproductive efforts (e.g., number of flowers) and success (e.g., number and mass of fruits or seeds) in response to warming have not been well-characterized. Here, we generated a global dataset of simulated warming experiments, consisting of 477 pairwise comparisons for 164 terrestrial species. We found evidence that warming overall decreased fruit number and increased seed mass, but little evidence that warming influenced flower number, fruit mass, or seed number. The warming effects on seed mass were regulated by the pollination type, and insect-pollinated plants exhibited a stronger response to warming than wind-pollinated plants. We found strong evidence that warming increased the mass of seeds for the nondominant species but no evidence of this for the dominant species. There was no evidence that phylogenetic relatedness explained the effects of warming on plant reproductive effort and success. In addition, the effects of warming on flowering onset negatively related to the responses in terms of the number of fruits and seeds to warming, revealing a cascading effect of plant reproductive development. These findings provide the first quantification of the response of terrestrial plant sexual reproduction to warming and suggest that plants may increase their fitness by producing heavier seeds under a warming climate.

Floral scent emission is the highest at the second night of anthesis in Lonicera japonica (Caprifoliaceae)

AbstractFloral color change in diverse plants has been thought to be a visual signal reflecting changes in floral rewards, promoting pollinator foraging efficiency as well as plant reproductive success. It remains unclear whether olfactory signals co‐vary with floral color change. We investigated the production rhythms of floral scent and nectar associated with floral color change in Lonicera japonica. The flowers generally last 2–3 days. They are white on opening at night (N1) and become light yellow the following day (D1), yellow on the second night (N2), and golden on the second day of flowering (D2). Our measurements in the four stages indicated that nectar production decreased significantly from N1 and D1 to N2 and D2, tracking the floral color change. A total of 34 compounds were detected in floral scent and total scent emission was significantly higher in N2 than in the other three stages. The scent emission of three major compounds, Linalool, cis‐3‐Hexenyl tiglate, and Germacrene D was also significantly higher in N2, but the relative content of Linalool decreased gradually, cis‐3‐Hexenyl tiglate increased gradually, and the relative content of Germacrene D did not differ among the four measured stages. Greater scent emission by night than by day suggested a strong olfactory signal to attract nocturnal hawkmoths, the effective pollinators. However, floral scent rhythms in the four stages did not match the color change and nectar secretion, suggesting that floral color (visual) and scent (olfactory) in this species may play different roles in attracting or filtering various visitors.

Seasonal variation in the response of a monoecious crop to increased temperature and fertilizers.

Climate warming may affect the performance of plants directly through altering vegetative or reproductive traits, and indirectly through modifying interactions with their pollinators. On the other hand, the addition of fertilizers to the soil may increase the quantity and quality of floral rewards, favoring the visitation of pollinators and, consequently, the reproductive success of plants. However, it is still unknown whether fertilizers may counteract the effects of increased temperature on the vegetative, floral, and reproductive traits of plants, as well as on the interaction with their pollinators. The aim of this study is to evaluate the effects of the input of organic and synthetic fertilizers on several vegetative and floral traits, and on the rate of legitimate floral visitors and reproductive success of the squash during two seasons, under a scenario of an increase in ambient temperature. During the dry and the rainy seasons, three vegetative, eleven floral, and two reproductive traits, as well as the duration of visits and visitation rate of legitimate floral visitors were evaluated in squash plants distributed into six treatments in a bifactorial design: temperature (ambient or elevated temperature) and fertilizer (organic, synthetic or without supplementary fertilizers). Contrary to our predictions, we found that an increase of ~1.5°C in ambient temperature, positively influenced several vegetative, floral, and reproductive traits in this crop, and that organic fertilizers, in general, was not better than synthetic fertilizers in improving those traits. Interestingly, the response of the squash and indirectly on their legitimate floral visitors to the increase of temperature and the input of fertilizers vary widely among seasons, suggesting great temporal variation in plant-pollinator responses to temperature and nutrient availability, which makes food security more unpredictable.

Maternal drought stress induces abiotic stress tolerance to the progeny at the germination stage in sunflower

Climate change produces more frequent and intense drought events during seed development that can affect seed quality. Germination is critical to ensure plant growth and reproductive success but it can be impacted by various abiotic stresses. Here, we studied the effect of drought stress during sunflower seed development on the germination of the progeny. We applied different scenarios of drought stress during seed development in sunflower inbred lines and hybrids and assessed seed germination of the progeny. Drought stress during seed development provided tolerance to water, hypoxic, cold and salt stresses during seed germination and also induced lower dormancy. We established that the induction of these traits was not transgenerational but maternally transmitted and could be reproduced in sunflower hybrids. Drought stress during seed development decreased pericarp thickness and induced higher leakage of soluble electrolytes from pericarp but it also modified embryo metabolism. A metabolomics analysis showed that ABA, oligosaccharides and polyphenols accumulated differently in drought stress seeds and could also participate in the seed tolerance to abiotic stress conditions during germination. Altogether our results reveal an adaptative process that allows sunflower plants exposed to drought stress during their reproductive stage to produce seeds with higher fitness. Besides bringing novel insight on natural adaption of plant populations to climate change, these results may have implications for the seed industry through the production of seeds resilient to higher climatic variability during the establishment of sunflower crop. • Drought stress during sunflower seed development induces seed tolerance to abiotic stresses and lower dormancy • The modulation of germinative properties by the environment is not transgenerational but maternally transmitted • Seed pericarp and embryo both play a role in the inheritance of germinative traits

Inflorescence temperature influences fruit set, phenology, and sink strength of Cabernet Sauvignon grape berries.

The temperature during the bloom period leading up to fruit set is a key determinant of reproductive success in plants and of harvest yield in crop plants. However, it is often unclear whether differences in yield components result from temperature effects on the whole plant or specifically on the flower or fruit sinks. We used a forced-convection, free-air cooling and heating system to manipulate the inflorescence temperature of field-grown Cabernet Sauvignon grapevines during the bloom period. Temperature regimes included cooling (ambient −7.5°C), heating (ambient +7.5°C), an ambient control, and a convective control. Cooling significantly retarded the time to fruit set and subsequent berry development, and heating shortened the time to fruit set and accelerated berry development relative to the two controls. Fruit set was decreased in cooled inflorescences, but although the cooling regime resulted in the lowest berry number per cluster, it also decreased seed and berry weight at harvest while not affecting seed number. Cooling inflorescences slightly decreased fruit soluble solids and pH, and increased titratable acidity, but did not affect color density. The inflorescence temperature did not impact leaf gas exchange and shoot growth, and shoot periderm formation occurred independently of the timing of fruit ripening. These results suggest that the temperature experienced by grape flowers during bloom time impacts fruit set and subsequent seed and berry development. Suboptimal temperatures not only reduce the proportion of flowers that set fruit but also limit the sink strength of the berries that do develop after fruit set. Shoot vigor and maturation, and leaf physiology, on the other hand, may be rather insensitive to temperature-induced changes in reproductive development.

A Decrease in the Staminode-Mediated Visitor Screening Mechanism in Response to Nectar Robbers Positively Affects Reproduction in Delphinium caeruleum Jacq. ex Camb. (Ranunculaceae).

Simple SummaryNectar robbers frequently have direct or indirect negative effects on plant reproductive success. However, nectar robbers can also indirectly contribute to the reproductive success of plants in some cases. The negative effects of nectar robbing on plant reproductive success have been widely reported, but the reasons for possible positive effects demand further investigation. Hence, our study was designed to assess the effects of nectar robbers on the reproductive success of Delphinium caeruleum. This will facilitate an understanding of the mutualism between plants and their visitors.Nectar-robbing insects, which are frequently described as cheaters in plant–pollinator mutualisms, may affect plant reproductive fitness by obtaining nectar rewards without providing pollination services. The negative effects of nectar robbing on plant reproductive success have been widely reported, but the reasons for possible positive effects demand further investigation. The goal of the study was to evaluate the effects of nectar robbing on the reproductive success of Delphinium caeruleum. Two staminodes cover the stamens and pistils in the flowers of D. caeruleum, forming a “double door” type of structure that compels pollinators to physically manipulate the staminodes to access the sex organs. In order to explore whether the operative strength required to open the staminodes is affected by actions associated with nectar robbing, we set up five different treatment groups: no nectar robbing, natural nectar robbing, artificial nectar robbing, hole making, and nectar removal. A biological tension sensor was used to measure the operative strength required to open the staminodes in the flowers. We also assessed the effect of nectar robbing on the flower-visiting behavior of pollinators and the effect of nectar robbing on reproductive fitness by the flower. The results showed that the operative strength needed to open staminodes was reduced by nectar robbers but not by artificial nectar robbing, hole making, or nectar removal. The flowers’ continuous visitation rate and visitation frequency by pollinators decreased significantly in robbed flowers. Both the pollen export and pollen deposition in naturally robbed flowers were significantly higher than those in nonrobbed flowers. Our results demonstrate that nectar robbers play an indirect positive role in the reproductive fitness of D. caeruleum flowers by reducing the operative strength of staminodes to promote pollen transfer. The reduction in operative strength of staminodes might be an adaptive mechanism that responds to nectar robbing.

Know when and how to die: gaining insights into the molecular regulation of leaf senescence.

Senescence is the ultimate phase in the life cycle of leaves which is crucial for recycling of nutrients to maintain plant fitness and reproductive success. The earliest visible manifestation of leaf senescence is their yellowing, which usually commences with the breakdown of chlorophyll. The degradation process involves a gradual and highly coordinated disassembly of macromolecules resulting in the accumulation of nutrients, which are subsequently mobilized from the senescing leaves to the developing organs. Leaf senescence progresses under overly tight genetic and molecular control involving a well-orchestrated and intricate network of regulators that coordinate spatio-temporally with the influence of both internal and external cues. Owing to the advancements in omics technologies, the availability of mutant resources, scalability of molecular analyses methodologies and the advanced capacity to integrate multidimensional data, our understanding of the genetic and molecular basis of leaf ageing has greatly expanded. The review provides a compilation of the multitier regulation of senescence process and the interrelation between the environment and the terminal phase of leaf development. The knowledge gained would benefit in devising the strategies for manipulation of leaf senescence process to improve crop quality and productivity.

Nonadditive effects of two contrasting introduced herbivores on the reproduction of a pollination-specialized palm.

Plant-animal interactions fall within a mutualism-antagonism continuum, exerting a wide range of effects on plant reproductive success. These effects become even more complex and diverse when several disparate animal species interact with the same plant species. Despite the increasing number of studies about the influence of herbivory on plant performance, the outcomes mediated by pollination and the combined impact of multiple herbivores on pollination-specialized plants are underexplored. In this study, we chose the Mediterranean dwarf palm Chamaerops humilis (Arecaceae) to illustrate the isolated and joint effect of two contrasting introduced herbivores, the palm borer Paysandisia archon (Lepidoptera, Castniidae) and feral goats, on pollinator abundance and plant reproductive success. To this aim, we monitored moth herbivory and goat herbivory in four palm populations in Mallorca (Balearic Islands) during 2019 and 2020. The effect of herbivory varied widely depending on both the herbivore and the pollinator species. Moth herbivory had a positive effect on pollinator abundance and fruit initiation, whereas goat herbivory had a negative effect on inflorescence production, pollinator abundance and fruit initiation. In addition, both herbivores exerted unexpected nonadditive effects on palm reproduction. Palms attacked by both herbivore species produced many more inflorescences (up to 18-fold) but had a lower fruit initiation success (close to zero) than unattacked palms or those attacked by a single herbivore species. Interestingly, only one of the two main pollinator species (the nitidulid beetle Meligethinus pallidulus) was impacted by herbivory. Our study highlights the need to investigate the possible nonadditive effects of all coexisting herbivores on plant performance, especially when establishing conservation plans and pest control strategies.

Periodically taken photographs reveal the effect of pollinator insects on seed set in lotus flowers

Understanding of pollination systems is an important topic for evolutionary ecology, food production, and biodiversity conservation. However, it is difficult to grasp the whole picture of an individual system, because the activity of pollinators fluctuates depending on the flowering period and time of day. In order to reveal effective pollinator taxa and timing of visitation to the reproductive success of plants under the complex biological interactions and fluctuating abiotic factors, we developed an automatic system to take photographs at 5-s intervals to get near-complete flower visitation by pollinators during the entire flowering period of selected flowers of Nelumbo nucifera and track the reproductive success of the same flowers until fruiting. Bee visits during the early morning hours of 05:00–07:59 on the second day of flowering under optimal temperatures with no rainfall or strong winds contributed strongly to seed set, with possible indirect negative effects by predators of the pollinators. Our results indicate the availability of periodic and consecutive photography system in clarifying the plant-pollinator interaction and its consequence to reproductive success of the plant. Further development is required to build a monitoring system to collect higher-resolution time-lapse images and automatically identify visiting insect species in the natural environment.

Estimación del servicio de polinización en un cultivo de alfalfa (Medicago sativa L.) mediante la cuantificación de flores disparadas

Biotic pollination directly affects yield of most of crop species. Therefore, monitoring the pollination service in a crop field is very important, although it rarely occurs. Certain pollination mechanisms, such as the explosive mechanism of flowers, would allow farmers to estimate the crop yield quickly and efficiently. The objective of this study is to evaluate a methodology for estimating the pollination service in crops with explosive pollination mechanism through the quantification of tripped flowers. For this, we used 16 alfalfa (Medicago sativa) lots in eight fields located in the Valle Bonaerense del Río Colorado, where we conducted pollination experiments and assessed the proportion of tripped flowers (visited) per inflorescence and the plant reproductive success (estimated as fruit set). Our results showed that a) in alfalfa, non-tripped flowers have a very low probability of becoming fruit, b) a single effective visit is sufficient for fructification, and c) successive visits do not increment the probability of fruit formation. On the other hand, we demonstrated that the proportion of tripped flowers is positively related to fruit set. Our results evidence that the assessment of tripped flowers can be an efficient tool to quantify the pollination service in a crop with an explosive mechanism. Although this methodology does not explain the causes of fructification deficiency, this tool may become the first step in crop problems detection, without neglecting the long-term studies that will improve pollination service in an effective way.