Effective Pollinators Research Articles

Pollination of Brassica campestris (Cruciferae) by Andrena savignyi (Andrenidae: Hymenoptera): Female vs. Male Pollination

Female and male solitary bees usually differ in their behavioral and morphological attributes and consequently in their pollination effectiveness. The current study was carried out at the research farm of The Islamia University of Bahawalpur, Pakistan, to compare the foraging behavior and pollination efficiency of female and male Andrena savignyi Spinola, 1838 on Brassica campestris. The impact of different environmental factors (temperature, relative humidity, light intensity and wind speed) on foraging behavior was also studied. Andrena savignyi was the most abundant floral visitor of B. campestris and comprised 52.17% of the floral visitors. Female individuals fed on both nectar and pollen while male fed on nectar. Visitation frequency, visitation rate, pollen harvest and pollen deposition of females were significantly higher than that of males because of their larger size and more dry weight. The maximum abundance of females was recorded at 12:00 pm followed by a sharp decline until 4:00 pm whereas males attained their maximum abundance at 2:00 pm. The female pollinated flowers resulted in greater pod weight, pod length, number of seeds per pod, seed weight per pod and germination percentage than the males. Our results suggest that females of A. savignyi deliver better pollination of B. campestris than males in terms of its reproductivesuccess and germination percentage. Future studies should emphasis on exploring the biology and ecology of A. savignyi with special focus of its artificial nesting.

Modern technologies for conducting beekeeping in the Republic of Belarus on the background of varroatous invasion

In the Republic of Belarus, as well as around the world, there is a continuous search for ways and methods of efficient struggle against the varroatous invasion of bees, however, no significant decisions are found in this struggle. In the context of this problem, scientific studies were conducted on development of modern technology of beekeeping on the background of spread varroatous invasion. Technological methods are proposed in the fight against varroatous invasion of bees, proving efficiency of the joint use of zoothechnical, biological and mechanical methods of combating the Varroa tick. It has been shown that purposeful rearing and selection of the drone brood reliably reduces the tick contamination of bee families by 5.7-17.4%. It has been substantiated that the use of intraulic pollen collector significantly reduces the number of ticks in the bees families, especially in the early spring period, when the ticks are mainly located on bees and are especially vulnerable to mechanical impact. The use of the feeding frame allows to purposefully obtain, conveniently and easily select the drone brood, and along with the drone brood, remove the Varroa tick form the bee nest. The use of the developed technology will allowed to reduce the number of tick, obtain additional products in the form of a homogenate of trutone larvae. Such system will increase the preservation of bee families, productivity of honey harvest and, as a result, increase the profitability of beekeeping production, as well as the effectiveness of pollination of entomophilic agricultural crops and their yield.

Moths can transfer pollen between flowers under experimental conditions

To be considered an effective pollinator, a floral visitor must not only be able to remove pollen but also transfer this pollen to a receptive conspecific stigma. While studies of diurnal pollination are commonplace, our understanding of the effectiveness of nocturnal pollinators is limited largely because of the difficulties of doing these studies at night. As a result of this, the way in which moths transfer pollen between flowers has been understudied globally, despite many authors suggesting they could be significant contributors to pollination.

Effects of pollination on the composition of volatile compounds in Coffea arabica L.

Pollination enhances coffee quality at the material level, improves the symbolic attributes of coffee and promotes sustainability. The objective of this work was to quantify the composition of volatile compounds in roasted coffee produced in the presence and absence of biotic pollination, aiming at investigating the effects of pollination on the composition of volatile compounds in coffee beans. This is the first report of its kind in the literature. The analysis of volatile compounds in roasted coffee beans showed that pollination increased the amount of volatile compounds in the beans; there was a significant increase in the amount of the following classes of compounds: pyrazines, pyrroles, pyridines, alcohols and phenols. Considering that most volatile compounds in roasted coffee are derived from reactions involving carbohydrates, proteins, chlorogenic acids and some alkaloids, our hypothesis is that pollinated coffee beans are better prepared for germination and for defense of the crop against attack by external agents. The findings of this study point to the important role played by sustainable practices implemented in coffee cultivation. The results obtained in this study pave the way toward the conduct of further investigations, including the analysis of the chemical composition of aroma precursors and volatile compounds in raw coffee beans, and the study of the sensory aspects of roasted coffee. © 2022 Society of Chemical Industry.

Hummingbird contribution to plant reproduction in the rupestrian grasslands is not defined by pollination syndrome.

Floral traits mediate the roles of distinct animals as effective pollinators along a generalization/specialization continuum. Many plant species are visited by different pollinator functional groups and the specific contribution of each group is expected to reflect the set of floral characteristics defined by pollination syndromes. Although considered a highly specialized nectarivorous group, hummingbirds frequently visit flowers lacking apparent specialization to bird pollination. How they contribute to the reproduction of these plants, however, has not been evaluated through field experiments considering multiple non-related plant species simultaneously. Here, we investigated hummingbirds' contributions to the pollination of ten plant species comprising a gradient of adaptation to bird pollination in the Brazilian rupestrian grasslands. We excluded hummingbirds from flowers and evaluated their relative contribution in comparison to insects (mainly bees) on conspecific/heterospecific pollen deposition and fruit set. Floral traits that are typically associated with bird pollination were associated with increased pollen deposition, but not with fruit set in the presence of hummingbirds. With hummingbirds, conspecific and heterospecific pollen deposition increased in most species, while fruit set increased in four plant species with varying degrees of fit to ornithophily. Our results show that assessing the relative contribution of specific pollinator groups may depend on when this contribution is measured, i.e. pollen deposition or fruit set. Considering fruit set, our results indicate that hummingbirds contributed to plant reproduction independently of the fit to bird pollination syndrome. This emphasizes their importance as under-appreciated generalized pollinators in some communities.

Mixed pollination system and floral signals of Paepalanthus (Eriocaulaceae): insects and geitonogamy ensure high reproductive success.

Eriocaulaceae exhibit a great variety of floral traits associated with insect (e.g. nectariferous structures) and wind pollination (unisexual flowers, exposed sexual organs and small pollen grains), as well as the 'selfing syndrome' (small flowers, short distance between stigma and anthers, and temporal overlap of male and female phases). Paepalanthus bifidus, P. subtilis and P. tortilis are related species that differ in form, size and colour of floral structures. We aimed to investigate the pollination and reproductive biology of these three species. We analysed the floral biology, floral visitors, pollinator behaviour, and the contribution of insects, wind and spontaneous geitonogamy to fruit set. We also evaluated the floral colour and scent of the species. Colour reflectance of capitula of each species was measured and plotted in models of insect vision. Floral scent samples were extracted and the compounds were compared to vegetative scent samples. In all species, the staminate and pistillate flowers are arranged in alternating cycles with a temporal overlap between these phases. Ants were the most frequent floral visitors and were effective pollinators in P. bifidus and P. tortilis, while flies were occasional pollinators in P. tortilis. Floral visitors were not observed in P. subtilis. In all species, fruits were produced by spontaneous geitonogamy, with no evidence of wind pollination. According to the models of insect vision, the colours of the capitula of P. bifidus and P. subtilis are the most inconspicuous for ants and flies. We found no difference between the emission of volatiles of inflorescences and vegetative structures. This study suggests that ant pollination might be more widespread in Eriocaulaceae than currently assumed. Furthermore, for small monocarpic plants, mixed mating strategies are most favourable, by ensuring reproduction either by outcrossing when pollinators are abundant or by spontaneous geitonogamy when pollinations are scarce/absent.

The evolution, ecology, and conservation of hummingbirds and their interactions with flowering plants.

The ecological co-dependency between plants and hummingbirds is a classic example of a mutualistic interaction: hummingbirds rely on floral nectar to fuel their rapid metabolisms, and more than 7000 plant species rely on hummingbirds for pollination. However, threats to hummingbirds are mounting, with 10% of 366 species considered globally threatened and 60% in decline. Despite the important ecological implications of these population declines, no recent review has examined plant-hummingbird interactions in the wider context of their evolution, ecology, and conservation. To provide this overview, we (i) assess the extent to which plants and hummingbirds have coevolved over millions of years, (ii) examine the mechanisms underlying plant-hummingbird interaction frequencies and hummingbird specialization, (iii) explore the factors driving the decline of hummingbird populations, and (iv) map out directions for future research and conservation. We find that, despite close associations between plants and hummingbirds, acquiring evidence for coevolution (versus one-sided adaptation) is difficult because data on fitness outcomes for both partners are required. Thus, linking plant-hummingbird interactions to plant reproduction is not only a major avenue for future coevolutionary work, but also for studies of interaction networks, which rarely incorporate pollinator effectiveness. Nevertheless, over the past decade, a growing body of literature on plant-hummingbird networks suggests that hummingbirds form relationships with plants primarily based on overlapping phenologies and trait-matching between bill length and flower length. On the other hand, species-level specialization appears to depend primarily on local community context, such as hummingbird abundance and nectar availability. Finally, although hummingbirds are commonly viewed as resilient opportunists that thrive in brushy habitats, we find that range size and forest dependency are key predictors of hummingbird extinction risk. A critical direction for future research is to examine how potential stressors - such as habitat loss and fragmentation, climate change, and introduction of non-native plants - may interact to affect hummingbirds and the plants they pollinate.

The Effective Pollination Period of European Plum (Prunus domestica L.) Cultivars in Western Norway

This study evaluated the effective pollination period (EPP) in four European plum (Prunus domestica L.) cultivars (‘Mallard’, ‘Edda’, ‘Jubileum’, and ‘Reeves’) during two years (2018–2019) under the environmental conditions in western Norway. The pollination of plum cultivars was carried out one, three, five, seven, and nine days after anthesis (DAA) with a pollen mix of two compatible cultivars (‘Victoria’ and ‘Opal’). Initial, middle-season, and final fruit set was recorded after one month and two months after pollination and just before the harvest, respectively. On average from both years cultivar ‘Jubileum’ had the highest fruit set when pollinated one, three, five, seven, and nine DAA (33.23%, 30.83%, 8.47%, 3.08%, and 1.15%, respectively), which was more than two folds higher fruit set than in the other studied cultivars. Cultivar ‘Jubileum’ showed significantly reduced fruit set between pollination on five and nine DAA, while cultivars ‘Mallard’, ‘Edda’, and ‘Reeves’ had markedly reduced fruit set if pollinated three to five DAA, implying that the EPP in ‘Jubileum’ was five days while in the rest it was three days. Variation of weather conditions during the flowering period in both years did not have a major effect on the receptivity of stigmas in the studied plum cultivars, which means that the existing differences in the length of EPP is maternal-genotype dependent.

Pistil Biology of ‘WA 38’ Apple and Effect of Pollen Source on Pollen Tube Growth and Fruit Set

‘WA 38’ (‘Enterprise’ × ‘Honeycrisp’) is an apple variety that is characterized by a peculiar self-thinning trait in which most of the fruitlets naturally shed within the first 8 weeks after bloom, leaving some clusters empty, but most with 1–2 apples. This study aimed to investigate potential causes for the relatively low fruit set observed in ‘WA 38’ by investigating its flower biology. This study comprised three objectives: (1) To characterize the effective pollination period (EPP) of ‘WA 38’ by studying stigmatic receptivity, pollen tube growth, and ovule longevity in ‘WA 38’ flowers, (2) to compare the pollen tube growth of 5 fully compatible pollinizer varieties in ‘WA 38’ pistils, and (3) to evaluate fruit and seed set resulting from controlled pollinations with 5 fully compatible pollinizer varieties. The results showed ‘WA 38’ EPP was approximately 3.2 days in 2019 and 1.4 days in 2020, and that differences in pollen sources did not attribute significant differences in fertility in ‘WA 38’ flowers. The results of this study suggest mechanisms other than pollination and fertilization, such as competition among fruitlets within a cluster or hormone signaling, may have a stronger impact on ‘WA 38’ fruitlet abscission.

Influence of Bee Scent and other indigenous bee attractants on bee activity and fruiting behaviour of kiwifruit (Actinidia deliciosa A. Chev.)

Kiwifruit is a dioecious plant requiring cross pollination. The nectar in kiwifruit flowers is negligible which makes it less attractive to honey bees. Hand pollination is a common practice for effective pollination but this practice is inevitable, laborious and time consuming. Spraying of bee attractants during the periods of anthesis can be helpful in increasing the bee visitation to the flowers and improve yield as well as quality of kiwifruits. Keeping in view the possible beneficial effects of bee attractants, an experiment was carried out during 2018–19 to compare the practice of hand pollination with the application of commercial bee attractant ‘Bee Scent’ (1.25%) and indigenous bee attractants like jaggery solution (10%), sugar solution (10%), honey solution (10%) and sugarcane juice (10%) for their effects on bee activity, fruit set and fruit quality of kiwifruit. The sprays of Bee Scent to the flowers resulted in significant improvement in bee visitation to the flowers, fruit set, yield, proportion of ‘A’ and ‘B’ grade fruits, fruit size & weight, number of seeds, TSS, sugars and ascorbic acid contents. Sugarcane juice was also found equally effective in improving bee activity, fruit set and fruit quality, thus shown the potential to be used as a bee attractant in commercial kiwifruit production system.

Contribuição do Programa BIOTA/FAPESP para o conhecimento sobre polinização e reprodução em plantas

Abstract Interactions between plant and pollinators are associated with the origin and maintenance of species diversity, as well as ecosystem functioning. The potential of pollination as an ecosystem service is evidenced by its association with food production. Understanding pollination at the landscape scale is essential for characterizing the pollination service for several crops that depend on pollinators for fruit and seed set that make up the human diet. Our aim was to carry out a literature review of studies and projects funded by BIOTA/FAPESP to illustrate the main research approaches developed in the field of Pollination Biology, especially related to plant-pollinator interactions. Plant-pollinator interactions in the Atlantic forest were leveraged as a result of this long-term research program, during which several papers were published in international journals. Pollination by bees (melittophily) was the most representative pollination system studied. In addition to melittophily, other interactions were studied such as pollination by hawkmoths (sphingophily), by hummingbirds (ornithophily) and by bats (chiropterophily). The specific mutualistic relationships between fig trees and fig wasps were also subject of studies within the Program. At the beginning of the BIOTA/FAPESP Program, there were many gaps in basic information about pollination and breeding systems of Brazilian native plant species. Thus, the Program was fundamental to fuel research on the natural history of plants and pollinators from the Atlantic forest. Overall, the Program funded studies that investigated themes such as functional pollination ecology, pollinator effectiveness, plant population genetics, structure and dynamics of plant-pollinator interaction networks, as well as geographic distribution and macroevolution of pollination systems, as well as genetic and molecular studies of native plant populations focusing on pollen flow and genetic structure of populations. Additionally, studies on pollination in the context of landscape ecology had the aim of assessing the effects of forest fragmentation on the functioning of plant populations and their interactions with pollinators and the relationships between landscape structure and ecological processes, biodiversity, and ecosystem service. Therefore, the Program had a prominent role in producing basic data with great implications for understanding the ecology and promoting the conservation of plant-pollinator interactions.

Diversity and Effectiveness of Native Insect Pollinators in Carrot Seed Production

Diversity and Effectiveness of Native Insect Pollinators in Carrot Seed Production

Agronomic Performances of Compost Associated with Pollinating Insects on the Growth and Yield of <i>Glycine max</i> (L.) Merril under Field Conditions

Soybean is an oilseed crop legume cultivated for its benefits as a source of protein to human or animal food. The cultivation of soybean will promote the diversification of income sources for rural population. Like other crops, soybean flowers are visited by insects. It is expected that within the biodiversity conservation program, anthophilous insects including bees, generally increase fruit and seed yields of many plant species. Therefore, the effect of insect pollinators and compost on growth and yield parameters of Glycine max was assessed for two cropping seasons (2018 and 2019) in the field. The experiment was set up in a complete randomized block design with three treatments: subplots applied with compost; subplots applied with fertilizer-NPK; subplots applied neither with compost, nor with fertilizer-NPK. Two other treatments were designed by plants with flowers protected against insects or flowers pollination free. Results indicate that root nodules formed by soybean plants in plots that received compost were significantly higher (P G. max flowers respectively. Lipotriches collaris was the most insect species frequently observed in the field, with 44.20% and 43.34% visits yearly respectively. The synergistic effect of insects and compost increased the number of seeds per pod by 28.27% and the percentage of normal seeds by 24.47%. Hence, applying Glycine max seeds at sowing with compost and in an environment with hives close to field could be recommended in agricultural development programs of farmers for a sustainable improvement of pods and seed yield of this valuable crop.

The Effect of Titanium Organic Complex on Pollination Process and Fruit Development of Apple cv. Topaz

Optimal weather conditions are necessary for the proper course of the flowering process and high activity of pollinators, which is the most important factor affecting pollination. Because weather conditions do not always favour effective pollination and because pollinators’ activities are decreasing, the application of compound stimulating pollination and fertilization may be a good perspective for increasing yield. Titanium is considered a beneficial element for plants. Preliminary studies have indicated the positive effect of titanium organic complex on pollen adhesion to the stigma and pollen germination on the stigma of tomato and cucumber. Therefore, a 2-year experiment was designed to determine the effect of titanium organic complex application on the pollination process and fruit development of apple cv. Topaz (Malus domestica Borkh.) The experiment demonstrated the positive effect of titanium organic complex on fertilization of ovules because of effective pollination, seed setting, and fruit development of apple. Application of titanium organic complex improved pollen adhesion to the stigma and pollen germination on the stigma. In addition, titanium organic complex increased the number of pollen tubes growing through the pistil style, which resulted in fertilization that was more effective, as confirmed by the higher number of seeds set in fruits. Higher numbers of seeds set in fruits positively affected their weight and size. Therefore, fruit harvested from trees to which titanium organic complex was applied were characterized by greater weight, length, and diameter compared to fruits obtained from the trees to which titanium organic complex was not applied.

Pollen viability and incompatibility in indigenous rice bean (Vigna umbellata (Thunb.) Ohwi & Ohashi)

Pollen viability, germination and compatibility are essential in determining the success of pollination and seed setting of high-valued crops. Rice bean (Vigna umbellata (Thunb.) Ohwi & Ohashi) is an underutilized and unexplored indigenous legume with high potential for commercial production. In this study, pollen quality, viability, germination rate and incompatibility among selected six rice bean (V. umbellata) accessions from Barili, Cebu, Philippines were evaluated to determine the barriers and effective pollination habit for increased productivity while retaining the important traits, including high tolerance in poor soils, superior climatic resilience and resistance to pest and diseases. Results of acetocarmine calorimetric assay showed that rice beans’ (V. umbellata) pollens are highly viable, with accessions VU 004 (56.33 ± 4.91%) and VU 007 (54.34 ± 4.53%) having the optimum viability rate. Brewbaker and Kwack medium treated with 0.2 g.l-1 and 0.3 g.l-1 boric acid (H3BO4) enhanced the germination rate in vitro (11.56 ± 5.53% and 9.47 ± 6.50% respectively). Bud (14.96 ± 1.53%) and post-anthesis pollens (10.28 ± 0.94%) have optimum germination rate in 0.2 g.l-1 boric acid media, while anthesis pollens are suitable in media supplemented with sucrose and boric acid alone (12.20 ± 1.50%) and with 0.1 g.l-1 myo-inositol supplementation (8.49 ± 1.86%). Pollination test revealed that rice bean accessions have high self-compatibility (50.76 + 3.45%) and low cross-compatibility (26.57 + 2.49%). The findings provide an important background in understanding the pollen quality and intraspecific interaction among indigenous rice bean (V. umbellata) accessions in Barili, Cebu to improve production and hybridization.

How to get rid of diploid bumblebee males – variability in wing size and shape does not allow within‐colony ploidy discrimination

AbstractThe bumblebee Bombus terrestris L. (Hymenoptera: Apidae) is an effective pollinator of both wild and cultivated plants and essential for the pollination of various important greenhouse crops. Because of its sex determination mechanism, homozygosity of the complementary sex determination (csd) locus due to inbreeding causes fertilized eggs to develop into diploid males, which represent a serious disadvantage for the colonies as their presence decreases colony growth and survival. The identification of diploid males is thus important from both ecological and economic points of view. In the present study, we applied the geometric morphometrics method on wing shape and size of B. terrestris diploid and haploid males at overall and intra‐colony levels to investigate wing changes between the two groups. We found that changes in wing shape concerned almost all cells investigated and male diploidy resulted in a narrower and slightly longer configuration. In addition, diploid male wings presented a very high variation both in size and shape, likely due to sub‐optimal temperature of incubation and food availability during their larval development. This strong variation of diploid male wings makes the ploidy discrimination by wing geometric morphometrics inaccurate based on small reference samples at the intra‐colony level even with allometric data correction, whereas it is accurate (precision >90%) at the overall level, in which sample size is high enough (i.e., 500 individuals). Therefore, our results indicated the need to create a large dataset to allow the analysis of few samples, as is the case with studies of wild bumblebee populations, small rearing companies, or preserved museum specimens. For this reason, we provide a large database of B. terrestris wing Procrustes coordinates (500 samples) to the bumblebee scientific community for use in the analysis of the determination of diploid male individuals.

Are floral traits good predictors of effective pollinators? A test of pollination syndromes

AbstractPollination syndromes have been widely used to predict the groups of pollinators of plants. Their predictability has been demonstrated for plant species pollinated by bees, birds, and bats. However, the importance of other aspects on the predictability of pollination syndromes still remain unknown. For instance, plant life cycle has not been considered in evaluations of the pollination syndrome predictability. The goal of this study was to evaluate the predictability of pollination syndromes in nine species with contrasting life cycles. Pollination syndromes were inferred based on floral traits of each plant species, whereas pollinator effectiveness of each group of floral visitors was established through pollen load analysis. Predictability of pollination syndromes was tested through the association between floral traits and the abundance of the most‐effective pollinators. Bees, flies, birds, beetles, and butterflies were the primary and secondary pollinators inferred from floral traits of each species. Although six out of the nine plant species studied were visited by effective pollinators; only four species were effectively pollinated by the groups of primary or secondary pollinators predicted from floral traits. However,Dahlia coccineaandTigridia pavoniawere the only species in which the predicted pollinator group was both effective and showed an association with floral traits. Pollination syndromes were not predictive of pollinators for any of the annual and perennial plant species. Although pollination syndromes are useful to understand some aspects of the reproductive biology of plant species, several other factors might have a role on their predictability.

Measurement report: Characterization of the vertical distribution of airborne <i>Pinus</i> pollen in the atmosphere with lidar-derived profiles – a modeling case study in the region of Barcelona, NE Spain

Abstract. This paper investigates the mechanisms involved in the dispersion, structure, and mixing in the vertical column of atmospheric pollen. The methodology used employs observations of pollen concentration obtained from Hirst samplers (we will refer to this as surface pollen) and vertical distribution (polarization-sensitive lidar), as well as nested numerical simulations with an atmospheric transport model and a simplified pollen module developed especially for this study. The study focuses on the predominant pollen type, Pinus, of the intense pollination event which occurred in the region of Barcelona, Catalonia, NE Spain, during 27–31 March 2015. First, conversion formulas are expressed to convert lidar-derived total backscatter coefficient and model-derived mass concentration into pollen grains concentration, the magnitude measured at the surface by means of aerobiological methods, and, for the first time ever, a relationship between optical and mass properties of atmospheric pollen through the estimation of the so-called specific extinction cross section is quantified in ambient conditions. Second, the model horizontal representativeness is assessed through a comparison between nested pollen simulations at 9, 3, and 1 km horizontal resolution and observed meteorological and aerobiological variables at seven sites around Catalonia. Finally, hourly observations of surface and column concentration in Barcelona are analyzed with the different numerical simulations at increasing horizontal resolution and varying sedimentation/deposition parameters. We find that the 9 or 3 km simulations are less sensitive to the meteorology errors; hence, they should be preferred for specific forecasting applications. The largest discrepancies between measured surface (Hirst) and column (lidar) concentrations occur during nighttime, where only residual pollen is detected in the column, whereas it is also present at the surface. The main reason is related to the lidar characteristics which have the lowest useful range bin at ∼ 225 m, above the usually very thin nocturnal stable boundary layer. At the hour of the day of maximum insolation, the pollen layer does not extend up to the top of the planetary boundary layer, according to the observations (lidar), probably because of gravity effects; however, the model simulates the pollen plume up to the top of the planetary boundary layer, resulting in an overestimation of the pollen load. Besides the large size and weight of Pinus grains, sedimentation/deposition processes have only a limited impact on the model vertical concentration in contrast to the emission processes. For further modeling research, emphasis is put on the accurate knowledge of plant/tree spatial distribution, density, and type, as well as on the establishment of reliable phenology functions.

Plant age at the time of ozone exposure affects flowering patterns, biotic interactions and reproduction of wild mustard

Exposure of plants to environmental stressors can modify their metabolism, interactions with other organisms and reproductive success. Tropospheric ozone is a source of plant stress. We investigated how an acute exposure to ozone at different times of plant development affects reproductive performance, as well as the flowering patterns and the interactions with pollinators and herbivores, of wild mustard plants. The number of open flowers was higher on plants exposed to ozone at earlier ages than on the respective controls, while plants exposed at later ages showed a tendency for decreased number of open flowers. The changes in the number of flowers provided a good explanation for the ozone-induced effects on reproductive performance and on pollinator visitation. Ozone exposure at earlier ages also led to either earlier or extended flowering periods. Moreover, ozone tended to increase herbivore abundance, with responses depending on herbivore taxa and the plant age at the time of ozone exposure. These results suggest that the effects of ozone exposure depend on the developmental stage of the plant, affecting the flowering patterns in different directions, with consequences for pollination and reproduction of annual crops and wild species.

Tropical bee species abundance differs within a narrow elevational gradient

Insect pollination is among the most essential ecosystem services for humanity. Globally, bees are the most effective pollinators, and tropical bees are also important for maintaining tropical biodiversity. Despite their invaluable pollination service, basic distributional patterns of tropical bees along elevation gradients are globally scarce. Here, we surveyed bees at 100 m elevation intervals from 800 to 1100 m elevation in Costa Rica to test if bee abundance, community composition and crop visitor assemblages differed by elevation. We found that 18 of 24 bee species spanning three tribes that represented the most abundantly collected bee species showed abundance differences by elevation, even within this narrow elevational gradient. Bee assemblages at the two crop species tested, avocado and squash, showed community dissimilarity between high and low elevations, and elevation was a significant factor in explaining bee community composition along the gradient. Stingless bees (Tribe Meliponini) were important visitors to both crop species, but there was a more diverse assemblage of bees visiting avocado compared to squash. Our findings suggest that successful conservation of tropical montane bee communities and pollination services will require knowledge of which elevations support the highest numbers of each species, rather than species full altitudinal ranges.