Plant Pollinator Research Articles

Quantifying High-Temperature-Induced Injury in Nanfeng Tangerine Plants: Insights from Photosynthetic and Biochemical Mechanisms

High temperatures significantly injure the flowering, pollination, fruit growth, and quality of plants. Photosynthesis, the fundamental process supporting plant life, is crucial. Nevertheless, the quantitative evaluation of the physiological activity of the photosynthetic system of Nanfeng tangerine (NT) plants under high-temperature conditions remains a challenge. This research utilized NT plants, a distinctive citrus variety in Jiangxi Province, as the experimental subject. The study investigated the effects of varying degrees of high-temperature stress and duration on 16 photosynthetic physiological parameters of NT plants. The study examined the impact of four varying high-temperature treatment levels (32/22 °C, 35/25 °C, 38/28 °C, and 41/31 °C) for durations of 2, 4, 6, and 8 days, respectively. Principal component analysis was utilized to identify the key indicators of photosynthetic physiological activity in NT plants, with Fv/Fm, Pmax, LCP, H2O2, MDA, and POD being selected as key parameters. The high-temperature stress index model previously constructed was used to calculate the high-temperature stress index value of the NT plants exposed to varying degrees and durations of high temperature, in order to provide a comprehensive assessment of the photosynthetic system of NT plants under high-temperature stress. Subsequently, the high-temperature stress levels were categorized into five levels based on the calculated values: Level 0 for 0 < HSI ≤ 2, Level 1 for 2 < HSI ≤ 4, Level 2 for 4 < HSI ≤ 6, Level 3 for 6 < HSI ≤ 8, and Level 4 for HSI > 8. The research results provide valuable data for agricultural meteorological departments to carry out disaster risk zoning and risk assessment in the future.

Effects of short- and long-term experimental warming on plant–pollinator interactions and floral rewards in the Low Arctic

Plant phenological and growth responses to experimental warming are widely documented, but less is known about warming effects on plant–pollinator interactions. We investigated the effects of short- and long-term passive warming on flowering phenology, insect visitation, fruit production, and floral rewards in the Low Arctic in northern Alaska. To better understand the role of insect visitors in plant reproductive success, we quantified pollen loads on floral visitors and tested for pollen limitation in four species. Long-term warming advanced flowering onset in evergreen shrubs and forbs. Warming, in general, increased the duration of flowering for forbs, evergreen shrubs, and deciduous shrubs. Considering all growth forms together, long-term warming increased floral density. This pattern was primarily driven by deciduous and evergreen shrubs. Dipterans accounted for more visits than Hymenopterans, although Hymenopterans had higher pollen loads. Insect exclusion and warming decreased fruit set in the forb, Bistorta officinalis Delarbre. Nectar volume in the deciduous shrub, Vaccinium uliginosum, was higher in the warmed plots than the control, but nectar quality did not differ. Advanced flowering onset, longer flowering duration, and increased flower density and nectar volume may have important implications for the pollinator community, warranting further research on long-term warming effects on tundra ecosystems.

Alpine Rhododendron population contractions lead to spatial distribution mismatch with their pollinators under climate change

The effect of global climate change on plant–pollinator interaction is not limited to changes in phenology and richness within communities but also includes the spatial mismatch caused by the inconsistency of geographical distribution changes. Subsequently, the pollinator interaction network may be remodeled or even disrupted. In this study, we simulated the suitable habitat niche of 15 Rhododendron species and their eight pollinator species as well as their overlapping versus geographical mismatch under the current and three future climate change scenarios in 2090s, using MaxEnt. Results showed that the suitable habitat of all Rhododendron species would decrease in 2090s. In particular, 10, 8, and 13 Rhododendron–pollinator assemblages would have a reduced spatial match region under the climate change scenarios, mainly due to the contraction of the suitable habitat of Rhododendron species. The results provide novel insights into the response of plant–pollinator interactions to global warming, useful to prioritize conservation actions of alpine plant ecosystems.

Effect of robbing intensity on reproductive success of Symphytum officinale (Boraginaceae).

The intervention of nectar robbers in plant pollination systems will cause some pollinators to modify their foraging behavior to act as secondary robbers, consequently adopting a mixed foraging strategy. The influence of nectar robbing on pollinator behavior may be affected by spatio-temporal difference of robbing intensity, and consequently, may have different effects on the pollination of host plants. However, whether and how the nectar robbing might influence pollinators under different robbing intensity still needs further investigation. In this study, Symphytum officinale was used to detect the effect of nectar robbers on pollinators under different robbing intensity as well as their effects on plant reproductive success. Six robbing levels and three bumblebees with mixed foraging behaviors were used to evaluate the effect of different robbing intensity on pollinator behavior, visitation rate, flower longevity and pollen deposition. Our results indicated that the robbing rate increased gradually with the proportion of robbed flowers, but which did not affect the frequency of legitimate visits. The increase of robbing rate promoted the corolla abscission, and then enhanced the self-pollen deposition, but which had no significant effect on cross-pollen deposition. These results indicate that the overall fitness of S. officinale was improved by combined self and cross-pollination modes when visited by both pollinators and nectar robbers simultaneously. Although nectar robbing is not uncommon, its consequences for pollination in the interaction web have not been well studied. Our results emphasize the significance of indirect impacts in mediating the adaptive outcomes of species interactions.

Dermaptera Community Structure on Oil Palm Ecosystem in Dharmasraya District, Indonesia

The oil palm ecosystem is one of the suitable habitats for the order Dermaptera. Several physical factors, especially humidity in the oil palm ecosystem, support these insects' existence. In the oil palm ecosystem, Dermaptera has several functions, including as a predator of oil palm pests, but on the other hand, these insects also prey on Elaeidobius kamerunicus Faust, the primary pollinator of oil palm plants. For that reason, research was conducted to study the structure of the Dermaptera community in the ecosystem of oil palm plantations in the Sitiung sub-district. This research was a survey conducted at three locations- Sitiung, Gunung Medan, and Sungai Duo Villages—the collection of insect samples by hand collection. Identification of insect samples was carried out at the species level according to Burr (1910) and Borror et al. (1996). In this study, 214 individuals of the order Dermaptera were found to consist of three species: Cheslisoches mario, Forficula auricularia, and Vostox brunneipennis. C. mario was the dominant Dermaptera species found with an Importance Value Index (IVI) was 1.27. Based on this research, it is known that the community structure of the order Dermaptera was simple because it has low diversity values.

Floral and pollinator functional diversity mediate network structure along an elevational gradient

AbstractElevational gradients in alpine ecosystems are well suited to study how plant and pollinator communities respond to climate change. In the Austrian Alps, we tested how the taxonomic and functional diversity of plants and their pollinators change with increasing elevation and how this affects plant–pollinator network structure. We measured the phenotypes of flowering plants and their pollinators and observed their interactions in 24 communities along an elevational gradient. To assess variation in floral and pollinator traits, we then quantified trait spaces (n-dimensional hypervolumes) occupied by flowers and pollinators in each community. To assess plant–pollinator network structure, we quantified the levels of complementary specialization (H2’), modularity and nestedness (weighted NODF) for each community. As elevation increased, most measures of diversity and network specialization either declined linearly or in an oscillating manner. Communities that exhibited higher pollinator functional diversity exhibited larger degrees of complementary specialization and modularity; and communities with greater floral and pollinator functional diversity and higher phylogenetic diversity were less nested. Altogether, the degree to which elevation, species diversity, functional diversity and network structure changed in conjunction suggests environmental effects on the functional and phylogenetic diversity of plants and pollinators and consequently network structure. Our results suggest that the effects of climate change on plant and pollinator community composition will impact plant–pollinator network structure and potentially pollination services at the community scale.

Utilization of Bumblebee in Crop Pollination

Bumblebees play a vital role in pollination of plants due to their large size and hairiness hence are ideal for picking up and transferring pollen. They can vibrate (‘buzz’) flowers and have no communication system but can work efficiently in tunnels as they have a better sense of direction. They are 400 times more efficient than honeybees at any pollination chore and are capable of visiting 30 to 50 flowers per minute. They are non-swarming and less aggressive than honeybees. Bumblebee generally forages during the early morning (0530-0800h) and evening (1700-1900h) time. Bumblebees are better pollinators than honeybees in greenhouses and glass houses and they have a great potential to serve as supplemental pollinators in the cultivation of crops such as tomato, eggplant, cucumber, melon, strawberry, pumpkin, cherry, sweet pepper, etc. It improves the yield and quality parameters of the fruits. In India, efforts are being made at Solan to mass rear bumble bees and utilize them in pollination. A few private companies have attempted to introduce newer species of bumblebees in India. In the present era, the global population of bumblebees is declining due to injudicious use of pesticides, loss of natural colony and mechanization in agriculture and climatic effect.

Japanese honey bees (Apis cerana japonica) have swarmed more often over the last two decades

The impacts of temperature increase are a concern for honey bees, which are major pollinators of crops and wild plants. Swarming is the reproductive behavior of honey bees that increases colony numbers. Honey bee colonies sometimes swarm multiple times, with each swarming termed a “swarming event” and a series of these events called a “swarming cycle.” The number of swarming events per swarming cycle varies widely depending on climatic conditions and subspecies, and the recent temperature increase due to global warming might be affecting the number of swarming events per swarming cycle of native honey bees. We clarified long-term changes in the number of swarming events per swarming cycle of Japanese honey bees (Apis cerana japonica) by collecting beekeepers’ swarming logbooks. The survey showed that between 2000 and 2022, Japanese honey bees swarmed 1 to 8 times per swarming cycle. Generalized linear model analysis indicated that year had a significant positive effect (coefficient, 0.03; 95% CI, 0.01–0.04); that is, the number of swarming events per swarming cycle showed a moderate increase over time. In addition, we found that colonies swarmed more often in a cycle when the swarming process began in early spring, especially in March. Considering the notably strong trend in Japan of warmer temperatures in March, the number of swarming events per swarming cycle may be increasing because reproduction is beginning earlier in the year. Further analyses are needed to verify the causal relationship of temperature increase on the number of swarming events per swarming cycle.

Fire effects on pollination and plant reproduction: a quantitative review.

Fire may favour plant flowering by opening the vegetation and increasing abiotic resource availability. Increased floral display size can attract more pollinators and increase the absolute fruit and seed production immediately after the fire. However, anthropogenic increases in fire frequency may alter these responses. We aim to assess the effects of fire on pollination and reproductive success of plants at the global scale. We performed a systematic literature review and meta-analyses to examine overall fire effects as well as different fire parameters on pollination and on plant reproduction. We also explored to what extent the responses vary among pollinators, pollination vectors, plant regeneration strategies, compatibility systems, vegetation types and biomes. Most studies were conducted in fire-prone ecosystems. Overall, single fires increased pollination and plant reproduction but this effect was overridden by recurrent fires. Floral visitation rates of pollinators were enhanced immediately following a wildfire, and especially in bee-pollinated plants. Fire increased the absolute production of fruits or seeds but not the fruit or seed set. The reproductive benefits were mostly observed in wind-pollinated (graminoids), herbaceous and resprouter species. Finally, fire effects on pollination were positively correlated with fire effects on plant reproductive success. Fire has a central role in pollination and plant sexual reproduction in fire-prone ecosystems. The increase in the absolute production of fruits and seeds suggests that fire benefits on plant reproduction are likely driven by increased abiotic resources and the consequent floral display size. However, reproduction efficiency, as measured by fruit or seed set, does not increase with fire. In contrast, when assessed on the same plant simultaneously, fire effects on pollination are translated into reproduction. Increased fire frequency due to anthropogenic changes can alter the nature of the response to fire.

Land-use affects pollinator-specific resource availability and pollinator foraging behaviour.

Land-use management is a key factor causing pollinator declines in agricultural grasslands. This decline can not only be directly driven by land-use (e.g., habitat loss) but also be indirectly mediated through a reduction in floral resource abundance and diversity, which might in turn affect pollinator health and foraging. We conducted surveys of the abundance of flowering plant species and behavioural observations of two common generalist pollinator species, namely the bumblebee Bombus lapidarius and the syrphid fly Episyrphus balteatus, in managed grasslands of variable land-use intensity (LUI) to investigate whether land-use affects (1) resource availability of the pollinators, (2) their host plant selection and (3) pollinator foraging behaviour. We have found that the floral composition of plant species that were used as resource by the investigated pollinator species depends on land-use intensity and practices such as mowing or grazing. We have also found that bumblebees, but not syrphid flies, visit different plants depending on LUI or management type. Furthermore, LUI indirectly changed pollinator behaviour via a reduction in plot-level flower diversity and abundance. For example, bumblebees show longer flight durations with decreasing flower cover indicating higher energy expenditure when foraging on land-use intensive plots. Syrphid flies were generally less affected by local land use, showing how different pollinator groups can differently react to land-use change. Overall, we show that land-use can change resource composition, abundance and diversity for pollinators, which can in turn affect pollinator foraging behaviour and potentially contribute to pollinator decline in agricultural grasslands.

Differential response of plant and insect pollinator communities to fragmentation in coastal dune slacks

Abstract Habitat destruction and fragmentation are one of the main drivers of pollinator decline and biodiversity loss in general. However, the exact effects of habitat fragmentation on pollinator communities are still poorly understood, and it remains unclear which patch characteristics are most important in driving pollinator diversity and community composition. In this study, we inventoried plant and insect diversity in a total of 19 fragmented dune slacks in Belgium. Specifically, we assessed the effects of dune slack area and connectivity on plant and pollinator diversity and community composition. Additionally, we investigated to what extent plant diversity had an impact on insect pollinator communities. The results indicated that species richness of both plants and insects was significantly related to patch area, whereas patch connectivity only had a significant effect on plant diversity. Nestedness analyses showed that plant communities of small dune slacks were a subset of the communities of large patches, but no such patterns were found for insect communities. Turnover in pollinator communities was high and significantly related to the distance separating dune slacks. Overall, our results highlight the importance of large patches for sustaining both plant and pollinator communities. Additionally, enhancing connectivity has the potential to promote plant diversity and consequently benefit pollinator species.

High pesticide exposure and risk to bees in pollinator plantings adjacent to conventionally managed blueberry fields

Wildflower plantings adjacent to agricultural fields provide diverse floral resources and nesting sites for wild bees. However, their proximity to pest control activities in the crop may result in pesticide exposure if pesticides drift into pollinator plantings. To quantify pesticide residues in pollinator plantings, we sampled flowers and soil from pollinator plantings and compared them to samples from unenhanced field margins and crop row middles. At conventionally managed farms, flowers from pollinator plantings had similar exposure profiles to those from unenhanced field margins or crop row middles, with multiple pesticides and high and similar risk quotient (RQ) values (with pollinator planting RQ: 3.9; without pollinator planting RQ: 4.0). Whereas samples from unsprayed sites had significantly lower risk (RQ: 0.005). Soil samples had overall low risk to bees. Additionally, we placed bumble bee colonies (Bombus impatiens) in field margins of crop fields with and without pollinator plantings and measured residues in bee-collected pollen. Pesticide exposure was similar in pollen from sites with or without pollinator plantings, and risk was generally high (with pollinator planting RQ: 0.5; without pollinator planting RQ: 1.1) and not significant between the two field types. Risk was lower at sites where there was no pesticide activity (RQ: 0.3), but again there was no significant difference between management types. The insecticide phosmet, which is used on blueberry farms for control of Drosophila suzukii, accounted for the majority of elevated risk. Additionally, analysis of pollen collected by bumble bees found no significant difference in floral species richness between sites with or without pollinator plantings. Our results suggest that pollinator plantings do not reduce pesticide risk and do not increase pollen diversity collected by B. impatiens, further highlighting the need to reduce exposure through enhanced IPM adoption, drift mitigation, and removal of attractive flowering weeds prior to insecticide applications.

Loss of functional diversity rather than species diversity of pollinators decreases community‐wide trait matching and pollination function

Abstract Loss of animal species and functional diversity can degrade ecosystem functions and services in plant–animal mutualistic networks, but their relative effects have rarely been previously examined in natural communities. Contrary to previously published theoretical results, under natural conditions, changes in pollinator functional niches caused by species and functional diversity losses are dynamic and often unpredictable. The lack of studies on natural networks limits our ability to predict future effects of decreasing pollinator diversity on wild and cultivated plants. We quantitatively evaluated the relative effects of pollinator species and functional diversity loss on plant–pollinator trait matching and pollination success across 40 spatiotemporally variable coastal networks. We found that low pollinator functional diversity (low abundance of long‐tongued pollinators) reduced community‐level plant functional specialization and trait matching between flowers and pollinators by reducing functional floral‐niche partitioning among pollinators. In contrast, pollinator species diversity did not influence community‐level trait matching. Furthermore, decreasing community‐level trait matching had a negative effect on community‐level plant pollination success, regardless of flower morphology. The present study demonstrated that pollinator functional diversity loss, rather than species diversity loss, was the main factor contributing to pollination functional loss in the plant–pollinator networks studied. We also demonstrated the importance of assessing functional aspects of plant–pollinator networks to evaluate community‐level pollination functional loss under global pollinator decline. Read the free Plain Language Summary for this article on the Journal blog.

Effects of Florivory on Floral Visitors and Reproductive Success of Sagittaria lancifolia (Alismataceae) in a Mexican Wetland.

Florivores consume floral structures with negative effects on plant fitness and pollinator attraction. Several studies have evaluated these consequences in hermaphroditic plants, but little is known about the effects on monoecious and dioecious species. We characterize the florivory and its effects on floral visitors and reproductive success in a monoecious population of Sagittaria lancifolia. Five categories of florivory were established according to the petal area consumed. Visits were recorded in male and female flowers within the different damage categories. Reproductive success was evaluated through fruit number and weight, as well as the number of seeds per fruit. Our results show that the weevil Tanysphyrus lemnae is the main florivore, and it mainly damages the female flowers. Hymenoptera were recorded as the most frequent visitors of both male and female flowers. Male and female flowers showed differences in visit frequency, which decreases as flower damage increases. Reproductive success was negatively related to the level of damage. We found that florivory is common in the population of S. lancifolia, which can exert a strong selective pressure by making the flowers less attractive and reducing the number of seeds per fruit. Future studies are needed to know how florivores affect plant male fitness.

Global Trends in Climate Suitability of Bees: Ups and Downs in a Warming World.

Bees represent vital natural assets contributing significantly to global food production and the maintenance of ecosystems. While studies on climate change effects impacting major pollinators like honeybees and bumblebees raise concerns about global diversity and crop productivity, comprehensive global-scale analyses remain limited. This study explores the repercussions of global warming on 1365 bees across seven families of bees worldwide. To compile a robust global bee occurrence dataset, we utilized the innovative 'BeeBDC' R package that amalgamated over 18.3 million bee occurrence records sourced from various repositories. Through species distribution models under the SSP585 scenario in the year 2070, we assessed how climate change influences the climate suitability of bees on a global scale, examining the impacts across continents. Our findings suggested that approximately 65% of bees are likely to witness a decrease in their distribution, with reductions averaging between 28% in Australia and 56% in Europe. Moreover, our analysis indicated that climate change's impact on bees is projected to be more severe in Africa and Europe, while North America is expected to witness a higher number (336) of bees expanding their distribution. Climate change's anticipated effects on bee distributions could potentially disrupt existing pollinator-plant networks, posing ecological challenges that emphasize the importance of pollinator diversity, synchrony between plants and bees, and the necessity for focused conservation efforts.

Impacts of Climate Change on Honey Bee Production in Jalalabad City Afghanistan

Beekeeping is emerging as a very successful, beneficial and profitable agricultural practice for local societies in Asian countries. This practice is not only related to beekeeping, but have intrinsic health benefits and importance through providing better food source with great nutritional value which is lacking in local or developed areas, beekeeping is also very important for various plant pollination and bees use pollen for their normal life. In rural areas there is almost an unlimited source of pollen and bees are having ability to pollinate natural local crops. In this regards honey bees are the most major pollinators of the cultivated crops in the world. If environmental temperature or climate changes could occur, that is significantly affecting honey bees biology, behavior, distribution and its production. But indirectly climate change or stream is natural enemy of local floral resources. Aim of this study was to evaluate the impact of climate changes on honey bee productions in Jalalabad surrounding areas. This study was completed from the surveys and inspection to identify the main climate change problems and its impact on honey bee’s production. This study was focused on the emerging view that climate changes had effected reducing of feed (reduction of flowers), facilitate less area for rearing of bees, reactions of the people against bee farms, pest, diseases and also climate change can effect physiology and behavior of the bees, decrease pollination rate and affects the production and size of the colonies. The beekeepers should have awareness from the weather conditions and must be emerge their farms to safe and floral resources areas.

Diversity and foraging activity of coffee insect pollinators in land near and far from the forest of North Sumatra, Indonesia

Abstract. Sinaga RR, Maryana N, Hidayat P. 2024. Diversity and foraging activity of coffee insect pollinators in land near and far from the forest of North Sumatra, Indonesia. Biodiversitas 25: 240-248. Coffee (Coffea spp.) is among the plant species that depend on insects to aid in its pollination process, where insect pollinators serve as intermediaries facilitating plant pollination. This study examined the diversity, abundance, and visiting activity of insect pollinators in coffee cultivation located in different areas, specifically those near the forest and those far from the forest in Simalungun District, North Sumatra. The study was carried out from September 2022 to February 2023 in six coffee cultivation sites spread across four sub-districts in Simalungun District, i.e., Silimakuta, Pematang Silimakuta, Purba, and Dolok Silau. The study's results revealed the presence of 16 species of insect pollinators in coffee cultivation near the forest and 13 species in those located far from the forest. The identified insect pollinators species were from Order Hymenoptera; Apis cerana, Lasioglossum sp., Dolichovespula norvegicoides, Diptera; Stomorhina discolor, Musca domestica, Bactrocera papayae, Nephrotoma flavescens, Episyrphus viridaureus, Oebalia sp., Coleoptera; Pachnaeus sp., Cantharis sp., Scarabaeidae sp 1., Maladera japonica, Lepidoptera; Agrotis segetum, Bradina diagonalis, and Nyctemera baulus. Notably, the abundance of coffee insect pollinators was more pronounced in close proximity to the forest compared to areas far from the forest. Regarding the visiting duration of these insects, S. discolor exhibited the longest visit duration of 76.46±1.19 seconds per flower, and the shortest duration in A. cerana was recorded at 8.35±0.23 seconds per flower.

The stingless bee Trigona spinipes (Hymenoptera: Apidae) is at risk from a range of insecticides via direct ingestion and trophallactic exchanges.

The stingless bee, Trigona spinipes, is an important pollinator of numerous native and cultivated plants. Trigona spinipes populations can be negatively impacted by insecticides commonly used for pest control in crops. However, this species has been neglected in toxicological studies. Here we observed the effects of seven insecticides on the survival of bees that had fed directly on insecticide-contaminated food sources or received insecticides via trophallactic exchanges between nestmates. The effects of insecticides on flight behavior were also determined for the compounds considered to be of low toxicity. Imidacloprid, spinosad and malathion were categorized as highly toxic to T. spinipes, whereas lambda-cyhalothrin, methomyl and chlorfenapyr were of medium to low toxicity and interfered with two aspects of flight behavior evaluated here. Chlorantraniliprole was the only insecticide tested here that had no significant effect on T. spinipes survival, although it did interfere with one aspect of flight capacity. A single bee that had ingested malathion, spinosad or imidacloprid, could contaminate three, four and nineteen other bees, respectively via trophallaxis, resulting in the death of the recipients. This is the first study to evaluate the ecotoxicology of a range of insecticides that not only negatively affected T. spinipes survival, but also interfered with flight capacity, a very important aspect of pollination behavior. The toxicity of the insecticides was observed following direct ingestion and also via trophallactic exchanges between nestmates, highlighting the possibility of lethal effects of these insecticides spreading throughout the colony, reducing the survival of non-foraging individuals. © 2023 Society of Chemical Industry.

Investigating the longstanding mystery of stigma length differences between morphs of distylous plants.

Longer stigmas in short-styled morphs of distylous plants have been considered an adaptive characteristic that increases intermorph pollen deposition. The greater pollen deposition in short-styled stigmas may be a by-product of their longer length, making deposition effectiveness comparison between morphs unfeasible. Thus, investigating which morph has the relatively most efficient stigma (i.e., pollen deposition per unit length) can boost our understanding of the adaptive significance of longer stigmas. Here, we compared pollen deposition between morphs relative to stigma length and assessed whether short-styled stigmas are more, less, or equally effective in receiving pollen grains per unit length. We reviewed the literature to characterize the extent of sigma length differences between morphs using the two most speciose distylous genera as model systems: Palicourea and Psychotria (Rubiaceae). Then, we conducted a between-morph comparison of raw and relative pollen depositions in a Palicourea rigida population. We confirmed that short-styled stigmas were longer than long-styled stigmas in both Palicourea (194.31% longer) and Psychotria (52.59% longer) flowers. Furthermore, in the focal Pal. rigida, although short-styled stigmas were 268.04% longer and received 97.04% more pollen grains than long-styled stigmas, the relative pollen deposition had a reverse pattern, with short-styled stigmas being two-times less efficient in receiving pollen. Our results indicate that the longer length of the short-styled stigmas may have a compensatory effect, increasing the chances of pollen grains reaching the stigma and probably maintaining disassortative intermorph pollination in distylous plants.

Effect of land-use intensity and adjacent semi-natural habitats on wild and honey bees of meadows

Most terrestrial ecosystems are shaped by the pollination service provided by insects, foremost bees. As bees are also important pollinators of crop plants, they are key for both the pollination of wild plants and for agricultural production. Meadows and semi-natural habitats (SNHs) are important habitats for bees. However, there is limited knowledge on how land-use intensity of meadows affects wild bees and managed Western honey bees. Further, it is unknown whether SNHs adjacent to meadows affect bees in meadows. Here, we examined in a landscape dominated by grasslands, the effects of land-use intensity (nitrogen input, grazing intensity, mowing frequency), flower availability and adjacent SNHs on bee communities in meadows. We recorded more than 5000 individuals of 87 species of bees and found no effect of land-use intensity on wild and honey bees. Flowering plant species richness had a positive effect on bee species richness in one study year. Though we recorded more bee species in SNHs than meadows, overall and specifically in ecologically specialized bee species (e.g. parasitic bees, oligoleges), the availability of adjacent SNHs did not affect bee abundance and richness in meadows. We discuss why land-use intensity and SNHs adjacent to meadows did not affect bees in meadows and conclude that SNHs are important in sustaining functionally diverse bee communities in landscapes dominated by grasslands.