Native Flowers Research Articles

Unraveling Evolutionary Dynamics: Comparative Analysis of Chloroplast Genome of Cleomella serrulata from Leaf Extracts

Cleomella serrulata is a native flowering plant found in North America. Even though this plant is of ecological and native medicinal importance, very little is known about the genomic makeup of Cleomella and the Cleomaceae family at large. Here, we report the complete chloroplast genome of Cleomella serrulata and provide an evolutionary comparison to other chloroplast genomes from Cleomaceae and closely related families. This study not only confirms the taxonomic placement of Cleomella as a distinct genus, but also provides phylogenetic insights that imply potential adaptive strategies and evolutionary mechanisms driving the genomic diversity of the Cleomella genus. Whole-genome-based and ANI comparisons indicate that the Cleomella species form a distinct clade that is about equidistant from the other Cleomaceae genera as it is from the genera from the nearby Capparaceae and Brassicaceae. This is the first complete chloroplast-based phylogenetic comparison of Cleomella species to other related genera and helps refine the complex taxonomic distinctions of Cleomaceae.

Impact of the annular solar eclipse on December 26, 2019 on the foraging visits of bees

Solar eclipse has remarkable effect on behavior of animals. South India experienced a 97% magnitude annular eclipse on December 26, 2019 during 08:04–11:04 h with the totality phase appeared during 09:25–09:30 h. We investigated whether the foraging activity of the bees was limited by the eclipse, what bees are affected most, and which part of the eclipse was critical for bee activities to understand how a group of insects that rely the Sun, the sunlight, and the sun rays for their navigation and vision behaves to the eclipse. We opted to watch the bees in their foraging ground, and selected the natural flower populations of Cleome rutidosperma, Hygrophila schulli, Mimosa pudica, and Urena sinuata—some of the bee-friendly plants—to record the visitor richness and visitation rate on the flowers on eclipse and non-eclipse days and during the hour of totality phase and partial phase of the eclipse. Fewer flower-visiting species were recorded on the eclipse day than on the non-eclipse days, but in the period of totality, very few bee species were active, and limited their activity to only one population of C. rutidosperma. Visits of honey bees and stingless bees were affected most, but not that badly of solitary bees and carpenter bees. Bees, particularly the social bees use Sun for navigation and deciphering information on forage sources to fellow workers. The eclipse, like for many other animals, might hamper bees’ orientation, vision, and flight.

Wild native insects are efficient pollinators of mangoes in the Northern Territory of Australia

Mango is an economically important fruit crop in tropical regions, including parts of Australia. However, the contribution of native flower visitors to mango pollination and fruit set is currently understudied. We studied cv. Kensington Pride (KP) in the Northern Territory (NT) of Australia to assess the overall contribution of insect pollinators to fruit set through pollinator exclusion treatments – open pollination, total pollinator exclusion and large pollinator exclusion (>5 mm). We also compared diurnal patterns in insect visitation with mango phenology and determined the pollination effectiveness and efficiency of flower visitors based on visitation rates, foraging behaviour and pollen deposition. At 45 days after the first pollinator survey, the number of fruits per panicle in open and large pollinator exclusion treatments was not significantly different from one another, despite large pollinator exclusion panicles receiving less than half of the number of insect visitations. Furthermore, open and large pollinator exclusion treatments had 28- and 30-times higher numbers of fruits per panicle than the total pollinator exclusion treatment, respectively, showing the importance of insect pollination. The native stingless bee Tetragonula mellipes was the most frequent visitor (7906 visits, 62.7 %), followed by a hover fly Mesembrius bengalensis (2404 visits, 19.1 %). Tetragonula mellipes had the highest mango pollen loads on their bodies and deposited more pollen grains on stigmas per visit than other flower visitors, and contributed 75.5 % to the mango pollination services, about 4.5 times more than the next most important pollinator (M. bengalensis: 16.8 %). Our results suggest that T. mellipes efficiently pollinate mango flowers in the NT when wild colonies are abundant in the native vegetation adjacent to the crop. Placing T. mellipes hives in the centre of larger mango orchards may increase pollination services and potentially farm productivity by ensuring good pollination towards the centre of orchard blocks.

Seeding roadsides is necessary but not sufficient for restoring native floral communities

Abstract The plant community in roadside right‐of‐ways is an important component of transportation infrastructure. Revegetation after construction is an opportunity to improve the plant community and create pollinator habitat. However, native seed mixes are substantially more expensive than those used in conventional roadside plantings, and transportation agencies often lack resources for management. Here, we compare the actively flowering plant community across a growing season in roadside plots seeded with native seed mixes versus non‐native seed mixes in Minnesota, USA. Plots varied in age from 2 to 20 years old. We demonstrate that native seeded plots had more native flowering forbs than non‐native seeded plots, as native flowers were rare in the non‐native seeded plots. However, despite some native species establishing well, many species in native seed mixes had poor or non‐existent establishment. Furthermore, the native and non‐native seeded plots converged in the makeup of their floral communities after a few years; part of this pattern is due to colonisation of species that were never seeded at either type of plot. Practical implication. If the goal of revegetation is to produce diverse, native dominated floral communities in roadsides, agencies must invest more in long‐term management. Managers could also alter seed mixes to remove species that fail to establish, which would reduce the cost of the seed mix, but not the diversity of the plant community that ultimately establishes. The use of such streamlined seed mixes across more land area would increase the availability of pollinator habitat without substantially altering current budgets or management plans.

Asclepiadaceae of Maharashtra

Family Asclepiadaceae is represented by 250 genera and ca 3000 species mainly distributed in tropical and subtropical regions of the world. It is represented by 43 genera and ca 243 species in India, of which, 31 genera, 82 species, 2 subspecies and 7 varieties are known from the State of Maharashtra. The family is well known for endemism, most elaborate complicated flower of all the dicots and contrivances for pollination. Most of the members of the family are restricted in distribution and many of them fall under some IUCN categories of rare plants. Many of the species are not available for taxonomic studies due to rarity of plant materials. Similarly fleshy nature of flowers makes it difficult to study floral structure in dried herbarium specimens. During last decade, deliberate attempts were made to collect asclepiads of Maharashtra and study their characters in fresh and prickled liquid preserved materials. During 10 years intensive survey of asclepiads of Maharashtra, about 63 species of the total 82 species reported for the State have been collected, documented, photographed, studied and reported in the present paper. The genus Ceropegia alone accounts for 24 species and 2 varieties for the state. Photographs of asclepiad flowers are found to be of paramount value in easy identifications than their descriptions. The paper gives an account of Asclepiads of Maharashtra, their distribution and present field status.

Spillover effects from invasive Acacia alter the plant-pollinator networks and seed production of native plants.

Invasive flowering plants can disrupt plant-pollinator networks. This is well documented where invasives occur amongst native plants; however, the potential for 'spillover' effects of invasives that form stands in adjacent habitats are less well understood. Here we quantify the impact of two invasive Australian species, Acacia saligna and Acacia longifolia, on the plant-pollinator networks in fynbos habitats in South Africa. We compared networks from replicate 1 ha plots of native vegetation (n = 21) that were subjected to three treatments: (1) at least 400 m from flowering Acacia; (2) adjacent to flowering Acacia, or (3) adjacent to flowering Acacia where all Acacia flowers were manually removed. We found that native flowers adjacent to stands of flowering Acacia received significantly more insect visits, especially from beetles and Apis mellifera capensis, and that visitation was more generalized. We also recorded visitation to, and the seed set of, three native flowering species and found that two received more insect visits, but produced fewer seeds, when adjacent to flowering Acacia. Our research shows that 'spillover' effects of invasive Acacia can lead to significant changes in visitation and seed production of native co-flowering species in neighbouring habitats-a factor to be considered when managing invaded landscapes.

Catharanthus roseus intoxication mimicking acute cholangitis

BackgroundCatharanthus roseus, a Madagascar native flowering plant, is known for its glossy leaves and vibrant flowers, and its medicinal significance due to its alkaloid compounds. As a source of vinblastine and vincristine used in chemotherapy, Catharanthus roseus is also employed in traditional medicine with its flower and stalks in dried form. Its toxicity can lead to various adverse effects. We report a case of Catharanthus roseus juice toxicity presenting as acute cholangitis, emphasizing the importance of healthcare providers obtaining detailed herbal supplement histories.Case presentationA 65-year-old woman presented with abdominal pain, fever, anorexia, and lower limb numbness. Initial diagnosis of acute cholangitis was considered, but imaging excluded common bile duct stones. Further investigation revealed a history of ingesting Catharanthus roseus juice for neck pain. Laboratory findings showed leukocytosis, elevated liver enzymes, and hyperbilirubinemia. The patient developed gastric ulcers, possibly due to alkaloids in Catharanthus roseus. No bacterial growth was noted in blood cultures. The patient recovered after discontinuing the herbal extract.ConclusionsCatharanthus roseus toxicity can manifest as fever, hepatotoxicity with cholestatic jaundice, and gastric ulcers, mimicking acute cholangitis. Awareness of herbal supplement use and potential toxicities is crucial for healthcare providers to ensure prompt diagnosis and appropriate management. This case emphasizes the need for public awareness regarding the possible toxicity of therapeutic herbs and the importance of comprehensive patient histories in healthcare settings.

Landscape-wide floral resource deficit enhances the importance of diverse wildflower plantings for pollinators in farmlands

Pollinators are declining rapidly, largely due to land conversion and intensification of agriculture. To mitigate their crisis, low-disturbance habitats, such as sown wildflower plantings, could promote pollinators by restoration of their resources. However, comprehensive knowledge is lacking on how landscape context, spatial configuration and age of wildflower plantings, seasonality and flower composition affect pollinator communities, especially from East-Central Europe. To understand these effects, we established diverse native wildflower plantings within heterogeneous and homogeneous agricultural landscapes, by two spatial configurations: one large field or three smaller strips, in Hungary. We sampled floral resources and wild pollinator insects (wild bees, hoverflies, butterflies), in early and mid-summer, for two years after establishment. Flower resources of the sown plant species increased continuously, and were complemented at high rate by flowering plant species from the soil seed bank, especially in the first year. Both flower abundance and diversity increased the abundance of pollinators, highlighting the important role of using diverse seed mixtures. Wild bee abundance and species richness increased year by year and season by season, while butterfly abundance also demonstrated a yearly increase after establishment. Hoverfly abundance and species richness, however, showed an opposite trend, possibly due to the inter-annual variation. Wild bee and butterfly abundance was higher in the heterogeneous than in the homogeneous landscapes. We did not observe any significant local effects of spatial configuration itself on pollinator populations. Wildflower plantings were particularly attractive for wild bees in flower-poor (homogeneous) landscapes during the flower-poor (mid-summer) period of the year. This can be explained by the increased contrast in flower resources between the wildflower plantings and the surrounding landscape, and highlights the importance of wildflower plantings in such conditions. Our results emphasise that to support pollinators effectively, future wildflower plantings should be maintained for multiple years, aim to maximise floral diversity and ensure continuously available flower resources throughout the entire season. They can be facilitated by i) using diverse seed mixtures of native flowering plants, ii) particularly focusing on plants that bloom during the crucial mid-summer period, iii) allowing the plant species to grow and bloom from the soil seed bank, and iv) using management techniques, which help to extend the flowering season. Further results from the upcoming years and similar long-term and landscape-scale experimental studies are needed to understand all the benefits and ecological processes of diverse native wildflower plantings especially in understudied European regions.

Diversity of bumble bees and butterflies in Minnesota roadsides depends on floral diversity and abundance but not floral native status

Abstract Habitat loss is an important driver in the rapid decline of many insects. The restoration of roadside habitat has been touted as an opportunity to support communities of bumble bees and butterflies, two insect groups of conservation concern. However, it is unclear how current roadside restoration methods translate to pollinator abundance and diversity. Here, we ask how the plant communities of roadsides seeded with native and non‐native seed mixes affect bumble bee and butterfly communities 2–20 years after planting. We found that bumble bee and butterfly abundance and diversity were positively correlated with floral abundance and diversity. However, the pollinator community in plots planted with diverse native seed mixes did not differ from that found in plots seeded with species‐poor non‐native mixes, likely because many forbs in the native seed mixes had poor establishment, and all plots were readily colonised by species that were never planted. While plots with more native flowers did not necessarily support higher pollinator diversity, we did find several native plants that established well in roadsides and supported pollinators, including goldenrods (Solidago spp.), milkweeds (Asclepias spp.) and wild bergamot (Monarda fistulosa). Our data suggest that managing a more diverse and abundant floral community will benefit bumble bees and butterflies. Refining the composition of native seed mixes, adding more floral abundance to non‐native mixes and investing in management for native plant communities may increase the habitat value of roadsides for pollinator communities.

Perennial flower margins reduce orchard fruit damage by rosy apple aphid, Dysaphis plantaginea (Homoptera: Aphididae)

Abstract Sown or natural flower strips are a commonly used management practice in agroecosystems and have been demonstrated to increase the abundance of predators of orchard pests. There is less evidence of the extent to which such strips can reduce pest damage in orchards. Here we examined the effect of managed, perennial flower margins on fruit damage by an economically significant crop pest, Dysaphis plantaginea, rosy apple aphid, in conventional apple orchards over 2 years, compared to orchards without flower margins. We found orchard flower margins reduced the percentage of apple trees with fruit damage by D. plantaginea, from 80% to 48%. In 2021, a period of severe infestation (65% of trees had fruit damage), there was reduced spread of D. plantaginea on infested apple trees and the number of trees with fruit damage was significantly reduced up to 50 m into orchards. During 2022, a period of lower infestation (25% of trees damaged), fruit damage was significantly reduced up to 10 m from the flower margin. A significant reduction in predation of aphids from bait cards in flower margin compared with control orchards suggests specialists, rather than generalist predators, may be driving the positive effects of the margin on pest pressure. There was no significant effect of flower margins on abundance of important aphid predators, including Syrphidae (hoverflies) and Coccinellidae (ladybirds). Synthesis and applications: To our knowledge, this study is the first to detect a reduction in fruit damage by pests at harvest in orchards with a flower margin. We highlight the potential for established perennial flower margins to deliver measurable, sustainable, D. plantaginea control benefits and provide insights into the optimal spatial arrangement of flower strips in orchards.

Variation in pollen load composition carried by wild bee species in native and nearby agricultural environments in south‐eastern Australia

Abstract Understanding the mechanisms by which wild bees survive in modified landscapes is important for their conservation and management as pollinators. Pollen is a critical resource for the completion of bee life cycles, so we investigated how the pollen loads carried by native bee communities change between natural forests and farms dominated by exotic crops and weeds in an agricultural region of south‐east Australia. We found that individual bees tended to carry higher proportions of exotic pollen on farms compared with forests (after accounting for whether they were captured on exotic or native flowers), and the diversity of pollen carried by bees did not differ significantly between native forest and farm sites or along native forest cover gradients. This suggests that the native bees found on farms, which are predominantly different species compared with those found in native forests, are not disadvantaged by the dominance of exotic plants in these habitats (though impacts on larval nutrition were not investigated). While some native bees carried crop pollen, others almost exclusively carried the pollen of agricultural weeds (e.g., Arctotheca and Brassica species), such that some native bee species may pollinate and benefit from crops, whereas others may only persist on farms if agricultural weeds are tolerated.

Effect of neurotransmitters in drinking water and some medicinal flowers in broiler diet additives on body performances and some immune parameters

This study was conducted to under seek the incidence of some neurotransmitters in drinking water and native medicinal flowers (Alecea Kurdica – Gule Hero and Chamomile) flowers as diet additives on body growth and immune of broiler. 720 one day unsexed hatched chicks will distributed into 12 treatments, each treatment with three replicates (20 chicks), as following: T0 (control -standard diet), [T1 (0.2 g Endorphin), T2 (0.2 g Dopamine) and T3 (0.2 g Serotonin)/ L drinking water], [T4 )0.5 kg Hero flower) and T5) 0.5 kg Chamomile flower)/ 100 kg diet], T6 )0.2 g Endorphin+0.5 kg Hero flower(, T7 (0.2 g Dopamine+0.5 kg Hero flower(, T8 )0.2 g Serotonin+ 0.5 kg Hero flower(, T9 (0.2 g Endorphin+0.5 kg Chamomile flower), T10 (0.2 g/ Dopamine+0.5 kg Chamomile flower), T11= 0.2 g/ L Serotonin/ L drinking water + 0.5 kg Chamomile flower/ 100 kg diet. The addition of neurotransmitters and native flowers additives as immune modulator had significantly affected on body weight, body weight gain and production index and led to to significant increase (P≤ 0.01) in relative weights of spleen, Bursa of fabricius, Thymus and antibodies titer against ND and IB diseases, also decreased the stress ratio which represented by heterophil/ lymphocyte (H/L) especially in T3 and T11.

Ancient insect vision tuned for flight among rocks and plants underpins natural flower colour diversity.

Understanding the origins of flower colour signalling to pollinators is fundamental to evolutionary biology and ecology. Flower colour evolves under pressure from visual systems of pollinators, like birds and insects, to establish global signatures among flowers with similar pollinators. However, an understanding of the ancient origins of this relationship remains elusive. Here, we employ computer simulations to generate artificial flower backgrounds assembled from real material sample spectra of rocks, leaves and dead plant materials, against which to test flowers' visibility to birds and bees. Our results indicate how flower colours differ from their backgrounds in strength, and the distributions of salient reflectance features when perceived by these key pollinators, to reveal the possible origins of their colours. Since Hymenopteran visual perception evolved before flowers, the terrestrial chromatic context for its evolution to facilitate flight and orientation consisted of rocks, leaves, sticks and bark. Flowers exploited these pre-evolved visual capacities of their visitors, in response evolving chromatic features to signal to bees, and differently to birds, against a backdrop of other natural materials. Consequently, it appears that today's flower colours may be an evolutionary response to the vision of diurnal pollinators navigating their world millennia prior to the first flowers.

Use of Ipomoea involucrata B. flower as metallochromic indicator for complexometric titrations

The present work highlights the use of Ipomoea involucrate B. flower extract as a complexometric indicator in complex formation between the EDTA and the following metal solutions (Cu2,+ Ba2,+ Hg2+, Fe3+, and Bi3+). Ipomoea involucrate is a species of the Ipomoea genus, belonging to the family Convolvulaceae. This natural indicator was extracted in 2M HCl at 100 0C for 30-40 minutes, cooled and the extract filtered and extracted with ethyl acetate and the pigment extracted with amyl alcohol which was separated and concentrated over a water bath. The flower extract was screened for its use as an metallochromic indicator at different pHs in metal solutions of Cu2,+ Ba2,+ Hg2+, Fe3+, and Bi3+.This natural indicator from the results obtained gave sharp intense color change at the equivalence point of complex formation between the metals and the EDTA at both acidic and alkaline pHs in the metal solution of Cu2+ and Fe3+ and that with different amount of EDTA used in the titration, which increased as the pH value increased, while the ipomoea indicator gave sharp intense color change at the equivalence point of complex formation between the metals and the EDTA at alkaline pHs in the metal solution of Ba2+, Hg2+ and Bi3+ at pH > 10. Natural flower indicators could take the place of the synthetic metallochromic indicators currently used in conventional laboratories because these flower extracts have excellent performance with sharp and intense color change in end points during the complexometric titrations and simple, cost-effective and environmentally friendly extraction methods.

Phenological overlap between crop and pollinators: Contrasting influence of native and non‐native bees on raspberry fruits over the flowering season

Abstract Phenological overlap between crop flowering and pollinators is a crucial trait for the pollination of more than 75% of the world's crops. However, crop management rarely considers the seasonal aspect of plant–pollinator mutualism. Here, we investigate the phenological overlap between crops and pollinators and how it affects pollination and fruit production. We measured the abundance and richness of native and non‐native pollinators visiting raspberry flowers at two different times during the flowering season (i.e. early and late flowering periods) and examined their effects on crop yield in 16 fields. The community of pollinators foraging on raspberry flowers was more diverse and dominated by native pollinators during the early flowering period when most native plant species were flowering. Later in the season, when native flower resources declined in the surrounding environment, raspberry flowers were visited mainly by two non‐native bees: managed honeybees and the invasive bumblebee Bombus terrestris. Pollinator contribution to raspberry yield was twice as high in the early flowering period compared to the late period (61% vs. 31% increase in drupelet set respectively). Flower damage caused by extremely high visitation frequencies by non‐native bees in the late period was six times higher than in the early flowering period (30% vs. 5% of damaged flowers respectively). Synthesis and applications. Providing sufficient pollen and nectar resources to support wild pollinators over extended periods in agricultural landscapes can contribute to crop pollination and ensure high fruit weight and quality. This can be achieved by restoring natural and semi‐natural areas near crop fields with native, long‐flowering plant species. Growers and crop breeding programmes should consider selecting flowering times that coincide with periods of high diversity or abundance of native pollinators to reduce dependence on managed pollinators.

Deep learning for Chilean native flora classification: a comparative analysis.

The limited availability of information on Chilean native flora has resulted in a lack of knowledge among the general public, and the classification of these plants poses challenges without extensive expertise. This study evaluates the performance of several Deep Learning (DL) models, namely InceptionV3, VGG19, ResNet152, and MobileNetV2, in classifying images representing Chilean native flora. The models are pre-trained on Imagenet. A dataset containing 500 images for each of the 10 classes of native flowers in Chile was curated, resulting in a total of 5000 images. The DL models were applied to this dataset, and their performance was compared based on accuracy and other relevant metrics. The findings highlight the potential of DL models to accurately classify images of Chilean native flora. The results contribute to enhancing the understanding of these plant species and fostering awareness among the general public. Further improvements and applications of DL in ecology and biodiversity research are discussed.

In silico and in vitro potentials of crocin and amphotericin B on Leishmania major: Multiple synergistic mechanisms of actions.

A significant barrier to optimal antileishmanial treatment is low efficacy and the emergence of drug resistance. Multiple approaches were used to monitor and assess crocin (a central component of saffron) mixed with amphotericin B (AmpB) potential in silico and in vitro consequences. The binding behavior of crocin and iNOS was the purpose of molecular docking. The results showed that crocin coupled with AmpB demonstrated a safe combination, extremely antileishmanial, suppressed Leishmania arginase absorption, and increased parasite death. This natural flower component is a robust antioxidant, significantly promoting the expression of the Th1-connected cytokines (IL12p40, IFN-γ, and TNF- α), iNOS, and transcription factors (Elk-1, c-Fos, and STAT-1). In comparison, the expression of the Th2-associated phenotypes (IL-10, IL-4, and TGF-β) was significantly reduced. The leishmanicidal effect of this combination was also mediated through programmed cell death (PCD), as confirmed by the manifestation of phosphatidylserine and cell cycle detention at the sub-GO/G1 phase. In conclusion, crocin with AmpB synergistically exerted in vitro antileishmanial action, generated nitric oxide and reactive oxygen species, modulated Th1, and Th2 phenotypes and transfer factors, enhanced PCD profile and arrested the cell cycle of Leishmania major promastigotes. The main action of crocin and AmpB involved wide-ranging mechanistic insights for conducting other clinical settings as promising drug candidates for cutaneous leishmaniasis. Therefore, this combination could be esteemed as a basis for a potential bioactive component and a logical source for leishmanicidal drug development against CL in future advanced clinical settings.

Petunia dihydroflavonol 4-reductase is only a few amino acids away from producing orange pelargonidin-based anthocyanins.

Anthocyanins are responsible for the color spectrum of both ornamental and natural flowers. However, not all plant species produce all colors. For example, roses are not blue because they do not naturally possess a hydroxylase that opens the pathway for delphinidin and its derivatives. It is more intriguing why some plants do not carry orange or scarlet red flowers with anthocyanins based on pelargonidin, because the precursor for these anthocyanins should be available if anthocyanins are made at all. The key to this is the substrate specificity of dihydroflavonol 4-reductase (DFR), an enzyme located at the branch point between flavonols and anthocyanins. The most common example is petunia, which does not bear orange flowers unless the enzyme is complemented by biotechnology. We changed a few amino acids in the active site of the enzyme and showed that the mutated petunia DFR started to favor dihydrokaempferol, the precursor to orange pelargonidin, in vitro. When transferred to petunia, it produced an orange hue and dramatically more pelargonidin-based anthocyanins in the flowers.

Plant invasion and fragmentation indirectly and contrastingly affect native plants and grassland arthropods

Plant invasion and habitat fragmentation have a detrimental effect on biodiversity in nearly all types of ecosystems. We compared the direct and indirect effects of the invasion of the common milkweed (Asclepias syriaca) on biodiversity patterns in different-sized Hungarian forest-steppe fragments. We assessed vegetation structure, measured temperature and soil moisture, and studied organisms with different ecological roles in invaded and non-invaded sites of fragments: plants, bees, butterflies, flower-visiting wasps, flies, true bugs, and spiders. Temperature and soil moisture were lower in invaded than in non-invaded area. Milkweed had a positive effect on plant species richness and flower abundance. In contrast, we mainly found indirect effects of invasion on arthropods through alteration of physical habitat characteristics and food resources. Pollinators were positively affected by native flowers, thus, milkweed indirectly supported pollinators. Similarly, we found higher species richness of herbivores in invaded sites than control sites, as species richness of true bugs also increased with increasing plant species richness. Predators were positively affected by complex vegetation structure, higher soil moisture and lower temperature. Furthermore, increasing fragment size had a strong negative effect on spider species richness of non-invaded sites, but no effect in invaded sites. Especially, grassland specialist spiders were more sensitive to fragment size than generalists, whereas generalist spider species rather profited from invasion. Although milkweed invades natural areas, we did not identify strong negative effects of its presence on the diversity of the grassland biota. However, the supportive effect of milkweed on a few generalist species homogenises the communities. The rate of invasion might increase with increasing fragmentation, therefore we recommend eliminating invasive plants from small habitat fragments to preserve the native biota. Focusing also on generalist species and revealing the indirect effects of invasions are essential for understanding the invasion mechanisms and would support restoration efforts.

Specific alien plant species predominantly deliver nectar sugar and pollen but are not preferentially visited by wild pollinating insects in suburban riparian ecosystems.

The invasion of alien plants has been rapidly proceeding worldwide due to urbanisation. This might be beneficial to wild pollinating insects, since some alien plant species have large flowers and/or long flowering periods, which can increase nectar sugar and pollen availability. To determine the relative contribution of alien plants to floral resource supply and whether resource-rich alien plants, if any, serve as an important food source of pollinating insects, we performed year-round field observations in suburban riverbanks. We quantified the per-unit-area availability of nectar sugar and pollen delivered by alien and native flowering species and counted wild flower visitors (bees and wasps, hoverflies and butterflies) per plant species. The available nectar sugar and pollen per area were predominantly delivered by a few specific alien species, and the relative contribution of other species to floral resource provision was low throughout the period that wild flower visitors were observed. Nonetheless, the resource-rich alien plants were not visited by as many insects as expected based on their contribution to resource provision. Rather, on a yearly basis, these plants received equal or even fewer visits than other flowering species, including resource-poor natives. We show that despite their great contribution to the gross floral resource supply, resource-rich alien plants do not serve as a principal food source for wild pollinating insects, and other plants, especially natives, are still needed to satisfy insect demand. For the conservation of pollinating insects in suburban ecosystems, maintaining floral resource diversity would be more beneficial than having an increase in gross floral resources by allowing the dominance of specific alien plants.