Redescription of Ilyocryptus brevidentatus Ekman, 1905 (Anomopoda,Cladocera, Branchiopoda)

During the wet season of 1999–2000, we studied the effects of the hydroperiod and other physical and chemical variables on planktonic copepod communities from six stations in Everglades National Park. Two stations were located in a slough (Taylor Slough 1, Taylor Slough 2) and four stations in the marl prairies of the Rocky Glades (Long Pine Key 7, Long Pine Key 8, Pa-hay-okee, Chekika). During the period of investigation, Taylor Slough sites had the longest hydroperiods, together with Pa-hay-okee, which is located near the eastern edge of Shark River Slough. Long Pine Key 7 and Long Pine Key 8 had the shortest hydroperiods, and Chekika had an intermediate hydroperiod. The pineland edge sites in the southern Rocky Glades (Long Pine Key) had higher numbers of individuals, and high percentages of larval stages, especially at the end of the wet season. The pineland ecotone is morphologically very heterogeneous, with solution holes in the limestone bedrock that provide below-ground refugia when there is no water on the marsh surface. The slough stations had the lowest numbers of individuals, as well as Chekika in the Rocky Glades, probably as a consequence of the altered water quality and hydropatterns caused by water management structures and operations We collected two species of calanoids, 18 cyclopoids, and three harpacticoids. The most abundant species were Acanthocyclops robustus, Tropocyclops prasinus mexicanus, Arctodiaptomus floridanus, Mesocyclops americanus, Macrocyclops albidus, Osphranticum labronectum, Microcyclops varicans, Microcyclops rubellus, Eucyclops conrowae, and Mesocyclops edax. Of these species, T. prasinus mexicanus and A. floridanus seemed to be adapted to short-hydroperiod habitats, M. rubellus and M. varicans to longer hydroperiod habitats, and E. conrowae to high conductivity habitats. Acanthocyclops robustus, M. albidus, and O. labronectum were dominant regardless of hydroperiod. As regards the temporal distribution, A. robustus was abundant throughout the entire wet season, M. edax, M. rubellus, M. americanus and M. varicans were most abundant in mid-wet season, in September–October, and T. prasinus mexicanus, M. albidus, and E. conrowae were abundant late in the wet season, in winter. The two calanoids only slightly overlapped in time: A. floridanus was abundant at the beginning of the wet season, in July–August, and O. labronectum was abundant at the end of the wet season, in December.     

Fly pollination in Ceropegia (Apocynaceae: Asclepiadoideae): biogeographic and phylogenetic perspectives

Background and Aims

Ceropegia (Apocynaceae subfamily Asclepiadoideae) is a large, Old World genus of >180 species, all of which possess distinctive flask-shaped flowers that temporarily trap pollinators. The taxonomic diversity of pollinators, biogeographic and phylogenetic patterns of pollinator exploitation, and the level of specificity of interactions were assessed in order to begin to understand the role of pollinators in promoting diversification within the genus.

Methods

Flower visitor and pollinator data for approx. 60 Ceropegia taxa were analysed with reference to the main centres of diversity of the genus and to a cpDNA–nrDNA molecular phylogeny of the genus.

Key Results

Ceropegia spp. interact with flower-visiting Diptera from at least 26 genera in 20 families, of which 11 genera and 11 families are pollinators. Size range of flies was 0·5–4·0 mm and approx. 94 % were females. Ceropegia from particular regions do not use specific fly genera or families, though Arabian Peninsula species are pollinated by a wider range of Diptera families than those in other regions. The basal-most clade interacts with the highest diversity of Diptera families and genera, largely due to one hyper-generalist taxon, C. aristolochioides subsp. deflersiana. Species in the more-derived clades interact with a smaller diversity of Diptera. Approximately 60 % of taxa are so far recorded as interacting with only a single genus of pollinators, the remaining 40 % being less conservative in their interactions. Ceropegia spp. can therefore be ecological specialists or generalists.

Conclusions

The genus Ceropegia has largely radiated without evolutionary shifts in pollinator functional specialization, maintaining its interactions with small Diptera. Intriguing biogeographic and phylogenetic patterns may reflect processes of regional dispersal, diversification and subsequent specialization onto a narrower range of pollinators, though some of the findings may be caused by inconsistent sampling. Comparisons are made with other plant genera in the Aristolochiaceae and Araceae that have evolved flask-shaped flowers that trap female flies seeking oviposition sites.Key words: Apocynaceae, Asclepiadoideae, Brachystelma, Ceropegia, Diptera, flower evolution, generalization, mutualism, pollination, Riocreuxia, specialization, Stapeliinae     

Efficiency of Malaise traps and colored pan traps for collecting flower visiting insects from three forested ecosystems

Pan and Malaise traps have been used widely to sample insect abundance and diversity, but no studies have compared their performance for sampling pollinators in forested ecosystems. Malaise trap design and color of pan traps are important parameters that influence insect pollinator catches. We compared pan trap (blue, yellow, white, and red) and Malaise trap catches from forests in three physiographic provinces (Piedmont, Coastal Plain, and Blue Ridge) of the southeastern United States. Similarities in trap performance between sites were observed with blue pan traps being most effective overall. Our results showed that various pollinator groups preferred certain pan trap colors and that adding color to Malaise traps influenced insect pollinator catches. However, pan traps generally caught more pollinators than Malaise traps. Because of their low cost and simplicity, using several colors of pan traps is an effective way to sample relative abundance and species richness of flower-visiting insects.     

不同人为干扰下林地类型对传粉昆虫的影响——以河南省巩义市为例

不同类型的林地为人类提供着十分重要的生态系统服务,维持着社会的稳定发展,其对传粉昆虫的保护也有着积极的效应。在巩义市选取24个采样点,3种林地类型(栓皮栎林、泡桐林、杨树林)进行取样,结合当地的植物群落特征,分析不同人为干扰梯度下生态系统对传粉昆虫的影响;共捕获传粉昆虫8386头,分属6个目,83个科,分属于膜翅目类、双翅目类、鞘翅目类、鳞翅目类、半翅目类与缨翅目类共六个传粉功能群。选取膜翅目、双翅目、鞘翅目和鳞翅目4类主要传粉昆虫作为研究对象进行分析。结果表明:(1)栓皮栎林中传粉昆虫的个体数量和优势度要大于泡桐林和杨树林,但泡桐林中传粉昆虫多样性大于栓皮栎林和杨树林;就传粉昆虫的多度而言,栓皮栎林与泡桐林(P0.05)和杨树林(P0.01)间有显著差异,而泡桐林和杨树林间的差异不明显;(2)非度量多维度法(NMDS)和非参数二因子相似性分析(ANOSIM)显示,泡桐林中传粉昆虫群落组成分别与栓皮栎林和杨树林之间存在显著差异(P0.05),而栓皮栎林与杨树林间无显著差异;(3)在所研究的7个环境因子中,根据冗余分析(RDA)显示,海拔高度和乔木盖度2个环境因素对传粉昆虫群落组成有显著影响(P0.05)。不同林地类型中传粉昆虫群落的组成差异明显,生境和植被的多样为物种带来更多的食源及栖息环境,因此,加强不同林地类型的保护、保障传粉昆虫生境的多样性对本区传粉昆虫的发展和生态系统服务的提高具有重要意义。     

Flower-strip agri-environment schemes provide diverse and valuable summer flower resources for pollinating insects

The diversity and abundance of insect pollinators are declining. This decline reduces the potential ecosystem services of pollination for wild and cultivated plants. Specific agri-environment schemes (AES) are subsidised to support and conserve biodiversity in farmlands. In Belgium, the pollinator flower-strips AES, strips of flower-rich hay meadows, has been promoted as a potential scheme to increase pollinator abundance and diversity, even if their effectiveness has not been locally evaluated. The main objective of this research is to assess the capacity of pollinator-strip AES to provide flower-resources to diverse pollinators. During 2 years, we monthly measured the availability of flower resources (pollen and nectar) produced on four flower-strips surrounded by intensive farming in Belgium. We counted and identified insects that visited these flowers, and we constructed the plant–insect interactions networks. The pollinator-strip AES presented a mix of both sown and spontaneous plant species. The ten sown plant species were all present, even after 8 years of strip settings. Three of them, Centaurea jacea, Lotus corniculatus, and Daucus carota were mainly visited for nectar collection, and a spontaneous non-sown species, Trifolium repens, had a key role in providing high-quality pollen to insects. Most of the observed flower-visiting insects belonged to common species of Hymenoptera and Diptera. All are considered highly efficient pollinators. The Belgian pollinator flower-strips are effective AES that provide flower resources to pollinators, mainly during summer and support pollination services. Nevertheless, spring and autumn flower resources remain poor and could reduce the strips’ effectiveness for supporting long-term insect diversity.     

The effects of urbanization on pollinators and pollination: A meta-analysis

Urbanization is increasing worldwide, with major impacts on biodiversity, species interactions and ecosystem functioning. Pollination is an ecosystem function vital for terrestrial ecosystems and food security; however, the processes underlying the patterns of pollinator diversity and the ecosystem services they provide in cities have seldom been quantified. Here, we perform a comprehensive meta-analysis of 133 studies examining the effects of urbanization on pollinators and pollination. Our results confirm the widespread negative impacts of urbanization on pollinator richness and abundance, with Lepidoptera being the most affected group. Furthermore, pollinator responses were found to be trait-specific, with below-ground nesting and solitary Hymenoptera, and spring flyers more severely affected by urbanization. Meanwhile, cities promote non-native pollinators, which may exacerbate conservation risks to native species. Surprisingly, despite the negative effects of urbanization on pollinator diversity, pollination service measured as seed set is enhanced in non-tropical cities likely due to abundant generalists and managed pollinators therein. We emphasize that the richness of local flowering plants could mitigate the negative impacts of urbanization on pollinator diversity. Overall, the results demonstrate the varying magnitudes of multiple moderators on urban pollinators and pollination services and could help guide conservation actions for biodiversity and ecosystem function for a sustainable future.     

Diverse visitors with various pollinator importance and temporal change in the important pollinators of <Emphasis Type="Italic">Geranium thunbergii</Emphasis> (Geraniaceae)

Assessing pollinator importance of each floral visitor to a plant species is a key to understanding plant–pollinator interaction. The present study examined visitation frequency, pollination efficiency, and pollinator importance of the full range of floral visitors to Geranium thunbergii natural population, by measuring seed-set. During 2 years of observations, the flowers were visited by at least 45 insect species belonging to four orders. Among the main 22 visitor species, 11 species belonging to three orders (Hymenoptera, Diptera, and Lepidoptera) acted as the efficient pollinators. In both years, Hymenoptera, especially bees, was the most important pollinator to G.thunbergii. Thus, the flowers could be considered as bee-pollinated. However, the most important species were not constant between years. The study also documented that the efficient pollinators have larger body sizes. The dish-shaped floral morphology, taxonomically diverse pollinators, and temporal change in the most important pollinators indicate that G.thunbergii–pollinator interaction is a rather generalized system. The results suggest that casual observations of visitation, or even precise measurement of pollinator importance in a single season is insufficient to identify important pollinators.     

Feedback effects between plant and flower-visiting insect communities along a primary succession gradient

Primary successions of glacier forelands are unique model systems to investigate community dynamics and assembly processes. However, successional changes of plant and insect communities have been mainly analysed separately. Therefore, changes in plant–insect interactions along successional gradients on glacier forelands remain unknown, despite their relevance to ecosystem functioning. This study assessed how successional changes of the vegetation influenced the composition of the flower-visiting insect assemblages of two plant species, Leucanthemopsis alpina (L.) Heyw. and Saxifraga bryoides L., selected as the only two insect-pollinated species occurring along the whole succession. In addition, we investigated the links between reproductive output of these plants and pollinator abundance through experimental exclusion of pollinators. Plant community structure changed along the succession, affecting the distribution and the abundance of insects via idiosyncratic responses of different insect functional groups. L. alpina interacted with ubiquitously distributed pollinators, while S. bryoides pollinators were positively associated with insect-pollinated plant species density and S. bryoides abundance. With succession proceeding, insect assemblages became more functionally diverse, with the abundance of parasitoids, predators and opportunists positively related to an increase in plant cover and diversity. The reproductive output of both plant species varied among successional stages. Contrary to our expectation, the obligate insect-pollinated L. alpina showed a reproductive output rather independent from pollinator abundance, while the reproductive output of the self-fertile S. bryoides seemed linked to pollinator abundance. Observing ecological interactions and using functional traits, we provided a mechanistic understanding of community assembly processes along a successional gradient. Plant community diversity and cover likely influenced insect community assembly through bottom-up effects. In turn, pollinators regulate plant reproductive output through top-down control. We emphasise that dynamics of alpine plant and insect communities may be structured by biotic interactions and feedback processes, rather than only be influenced by harsh abiotic conditions and stochastic events.     

Insect pollinators diversity and abundance in Eruca sativa Mill. (Arugula) and Brassica rapa L. (Field mustard) crops

Studies on the insect pollinators diversity and their relative abundance in Eruca sativa Mill. (Arugula) and Brassica rapa L. (field mustard) was carried out during spring season from February to April consecutively during all the three years of 2016–18. Insect pollinators observed belonged to four orders i.e. Hymenoptera, Diptera, Lepidoptera, and Coleoptera. A total of 20 major species of insect pollinators were recorded. The highest abundance of pollinator species belonged to Hymenoptera. The most prominent insect pollinator species were Apis mellifera followed by other three honey bee species of A. cerana, A. florea, and A. dorsata respectively. Some species of solitary bees were also recorded. From Diptera, four species of syrphid fly and one species from Muscidae family were also recorded. Insect pollinators recorded from order Lepidoptera were Pieris brassicae, Vanessa cardui, and Papilio demoleus. Lady bird beetle Coccinella septempunctata was recorded from Coleoptera order as occasional visitor. It was noticed that E. sativa attracted more insect pollinators than B. rapa which may be attributed to different amount and chemical properties of nectar, with number of pollen grains, and flower canopy of both crops. Further studies are needed to confirm the reasons for higher pollinator visitation to E. sativa than B. rapa through chemical analysis of nectar, amount of pollens, flower physiology and phenology of both crops.     

Post‐Hurricane Regeneration of Pioneer Plant Species in South Florida Subtropical Hardwood Hammocks1

After Hurricane Andrew crossed southern Florida (U.S.A.) on 24 August 1992, native and exotic pioneer species in subtropical hardwood forests (hammocks) regenerated from seed banks. Regeneration occurred in hammocks of metropolitan Dade County and the Long Pine Key region of Everglades National Park. The density of the native pioneer Trema micrantha was significantly higher in hammocks of Long Pine Key than in those of metropolitan Dade County. In contrast, the basal area of the exotic pioneer Carica papaya was greater in Dade County hammocks than Long Pine Key hammocks. Although T. micrantha tended to be restricted to areas of soil disturbance (tip‐up pits) formed by trees uprooted during Hurricane Andrew, especially in Long Pine Key, C. papaya was located throughout hammocks. These results suggest differences in the regeneration niches in which the native T. micrantha required more specific disruptions (i.e., both canopy and soil) than C. papaya (only removal of canopy) for establishment. A broad regeneration niche could in part account for the capability of an exotic species with a dormant seed bank to invade native subtropical forests following natural large‐scale disturbances.     

Spatial patterns of fish communities along two estuarine gradients in southern Florida

In tropical and subtropical estuaries, gradients of primary productivity and salinity are generally invoked to explain patterns in community structure and standing crops of fishes. We documented spatial and temporal patterns in fish community structure and standing crops along salinity and nutrient gradients in two subtropical drainages of Everglades National Park, USA. The Shark River drains into the Gulf of Mexico and experiences diurnal tides carrying relatively nutrient enriched waters, while Taylor River is more hydrologically isolated by the oligohaline Florida Bay and experiences no discernable lunar tides. We hypothesized that the more nutrient enriched system would support higher standing crops of fishes in its mangrove zone. We collected 50 species of fish from January 2000 to April 2004 at six sampling sites spanning fresh to brackish salinities in both the Shark and Taylor River drainages. Contrary to expectations, we observed lower standing crops and density of fishes in the more nutrient rich tidal mangrove forest of the Shark River than in the less nutrient rich mangrove habitats bordering the Taylor River. Tidal mangrove habitats in the Shark River were dominated by salt-tolerant fish and displayed lower species richness than mangrove communities in the Taylor River, which included more freshwater taxa and yielded relatively higher richness. These differences were maintained even after controlling for salinity at the time of sampling. Small-scale topographic relief differs between these two systems, possibly created by tidal action in the Shark River. We propose that this difference in topography limits movement of fishes from upstream marshes into the fringing mangrove forest in the Shark River system, but not the Taylor River system. Understanding the influence of habitat structure, including connectivity, on aquatic communities is important to anticipate effects of construction and operational alternatives associated with restoration of the Everglades ecosystem.     

Historical changes in the conductivity and ionic charateristics of the source water for the Shark River Slough,Everglades National Park,Florida, U.S.A.

Man-made changes in the hydrological regime of South Florida have significantly altered the conductivity and ionic composition of water in the Shark River Slough system of Everglades National Park. The shift in water inputs from unregulated marsh water flow to regulated delivery of canal water has resulted in a 140% increase in conductivity and 149% increase in total ionic concentration since the early 1960s. Associated with this change has been a 300–400% increase in sodium and chloride concentrations in the waters entering the Shark River Slough of Everglades National Park.     

Pollinator conservation at the local scale: flower density,diversity and community structure increase flower visiting insect activity to mixed floral stands

Insect pollinators play a keystone role in terrestrial ecosystems. The parallel declines in plant and pollinator communities emphasizes that plant-pollinator interactions at the community level are highly relevant for biodiversity conservation. Here we examine relationships between plants and flower-visiting insects (anthophiles) at the scale of local floral patches. We conducted a visitation survey during the spring flowering season, a peak time for pollinator activity in the threatened Cape Floristic Region, South Africa. We tested floral density, diversity and composition as predictors of anthophile diversity (measured at the family/family group level) and visitation rates in multispecies stands of flowers. Although different anthophile groups responded differently, generally anthophile visitation rates and diversity were positively affected by floral density, diversity and community structure. Anthophiles were more abundant and diverse in areas with a high density and diversity of flowers. Plant community structure affected both the likelihood of occurrence and activity of anthophiles in the plots. The two mass flowering species examined here, Relhania fruticosa and Salvia chamaeleagnea, were strong determinants of anthophile activity, greatly increasing visitation rates, even though there was, on average, lower floral density and diversity. Our results show that anthophile activity is affected by highly localised, small-scale factors, namely the density and diversity of flowers and community structure. Important among these factors are patches of high quality habitat, high in floral abundance and diversity, both of which should be included in landscape-level plans for pollinator conservation, providing stepping stones for these insects in transformed landscapes.     

Food for insect pollinators on farmland: insect visits to flowers of annual seed mixtures

Intensification of agriculture in recent decades has impoverished farmland for insect pollinators by removing their food plants. Arable farmland can be enhanced as a habitat for these insects by growing annual nectar- and pollen-producing herbaceous plants for them in non-cropped areas such as set-aside and field margins. In 1996 and 1997, observations were made in Hertfordshire, UK, on the flowering phenology and flower-attractiveness to visiting Hymenoptera, Diptera and Lepidoptera of plots sown to mixtures of six annual flowering plant species: borage (Borago officinalis), buckwheat (Fagopyrum esculentum), cornflower (Centaurea cyanus), mallow (Malva sylvestris), marigold (Calendula officinalis) and phacelia (Phacelia tanacetifolia) in different proportions. The mixtures had good agronomic and biological properties. They established and flowered well from a range of seed rates and sowing-dates. They attracted a diversity of flower-visiting insects, including the honey bee and eightspecies of bumble bee amongst 16 species of aculeate Hymenoptera, 17 species of Diptera, mostly syrphids, and six species of Lepidoptera. Sequential sowings provided nectar and pollen from early summer to late autumn during the period after arable crops had finished flowering and food for pollinators was scarce. Different insect species were favoured by different sowing-dates and plant species     

Precipitation and predation risk alter the diversity and behavior of pollinators and reduce plant fitness

Biotic and abiotic factors may individually or interactively disrupt plant–pollinator interactions, influencing plant fitness. Although variations in temperature and precipitation are expected to modify the overall impact of predators on plant–pollinator interactions, few empirical studies have assessed if these weather conditions influence anti-predator behaviors and how this context-dependent response may cascade down to plant fitness. To answer this question, we manipulated predation risk (using artificial spiders) in different years to investigate how natural variation in temperature and precipitation may affect diversity (richness and composition) and behavioral (visitation) responses of flower-visiting insects to predation risk, and how these effects influence plant fitness. Our findings indicate that predation risk and an increase in precipitation independently reduced plant fitness (i.e., seed set) by decreasing flower visitation. Predation risk reduced pollinator visitation and richness, and altered species composition of pollinators. Additionally, an increase in precipitation was associated with lower flower visitation and pollinator richness but did not alter pollinator species composition. However, maximum daily temperature did not affect any component of the pollinator assemblage or plant fitness. Our results indicate that biotic and abiotic drivers have different impacts on pollinator behavior and diversity with consequences for plant fitness components. Even small variation in precipitation conditions promotes complex and substantial cascading effects on plants by affecting both pollinator communities and the outcome of plant–pollinator interactions. Tropical communities are expected to be highly susceptible to climatic changes, and these changes may have drastic consequences for biotic interactions in the tropics.     

Effects of different types of low‐intensity management on plant‐pollinator interactions in Estonian grasslands

In the face of global pollinator decline, extensively managed grasslands play an important role in supporting stable pollinator communities. However, different types of extensive management may promote particular plant species and thus particular functional traits. As the functional traits of flowering plant species (e.g., flower size and shape) in a habitat help determine the identity and frequency of pollinator visitors, they can also influence the structures of plant−pollinator interaction networks (i.e., pollination networks). The aim of this study was to examine how the type of low‐intensity traditional management influences plant and pollinator composition, the structure of plant−pollinator interactions, and their mediation by floral and insect functional traits. Specifically, we compared mown wooded meadows to grazed alvar pastures in western Estonia. We found that both management types fostered equal diversity of plants and pollinators, and overlapping, though still distinct, plant and pollinator compositions. Wooded meadow pollination networks had significantly higher connectance and specialization, while alvar pasture networks achieved higher interaction diversity at a standardized sampling of interactions. Pollinators with small body sizes and short proboscis lengths were more specialized in their preference for particular plant species and the specialization of individual pollinators was higher in alvar pastures than in wooded meadows. All in all, the two management types promoted diverse plant and pollinator communities, which enabled the development of equally even and nested pollination networks. The same generalist plant and pollinator species were important for the pollination networks of both wooded meadows and alvar pastures; however, they were complemented by management‐specific species, which accounted for differences in network structure. Therefore, the implementation of both management types in the same landscape helps to maintain high species and interaction diversity.     

Pollinator assemblages on dandelions and white clover in urban and suburban lawns

Flowering weeds, though often deemed undesirable in turfgrass lawns, provide food resources for declining pollinator populations in urbanized landscapes. We sampled bees and other pollinators directly from flowering common dandelion (Taraxacum officinale) and white clover (Trifolium repens) in lawns of similar character in central Kentucky USA to identify species likely to be exposed if such weeds are inadvertently oversprayed during application of lawn insecticides. We also tested the hypothesis that pollinator assemblages visiting spring-blooming white clover in urban and suburban lawns are as species-rich and diverse as in more rural lawn settings. We collected about 50 different species of insect pollinators, including 37 species of bees, from the aforementioned lawn weeds. Two of the six species of bumble bees (Bombus spp.) collected are considered uncommon and possibly in decline. Hover flies (Syrphidae), honey bees (Apis mellifera), and non-Apid wild bees predominated on dandelions whereas proportionately fewer hover flies and more A. mellifera and Bombus spp. visited white clover, especially in summer. Species richness of bees visiting white clover was similar in urban, suburban or periurban-rural lawns, although A. mellifera were proportionately more abundant, and Bombus spp. were less abundant, with increasing percentage of hardscape in surrounding areas. Fostering public awareness of the diversity of bees and other pollinators that visit flowering lawn weeds might help nurture a sociocultural shift toward more pollinator-friendly lawn care practices.     

The role of the endemic and critically endangered Colorful Puffleg Eriocnemis mirabilis in plant‐hummingbird networks of the Colombian Andes

Ecological network approaches may contribute to conservation practices by quantifying within‐community importance of species. In mutualistic plant‐pollinator systems, such networks reflect potential pollination of the plants and a considerable portion of the energy consumption by the pollinators, two key components for each party. Here, we used two different sampling approaches to describe mutualistic plant‐hummingbird networks from a cloud forest in the Colombian Western Andes, home to the Colorful Puffleg Eriocnemis mirabilis, an endemic and critically endangered hummingbird. We contrast networks between two localities (a protected area inside a National park vs. its buffer zone) and across sampling methods (floral visitation vs. pollen loads) to assess how the network structure and the importance of each hummingbird species within the networks may change. Visitation networks were characterized as having higher sampling completeness, yet pollen load network recorded more pollen types than plant species recorded by visitation. Irrespective of the sampling methods, the Colorful Puffleg was one of the most important hummingbird species in the network within the protected area inside the National park, but not in the buffer zone. Moreover, most species‐level network indices were related to hummingbirds’ abundance. This suggests that conservation initiatives aimed at the endangered Colorful Puffleg may both help on the survival of this endangered hummingbird, as well as on maintaining its key role in the mutualistic interaction network inside the National Park. Our study illustrates how conservation practitioners could assess the local importance of endangered species using interaction network approaches.     

Is there a benefit of excluding sheep from pastures at flowering peak on flower-visiting insect diversity?

Permanent grasslands are an important habitat for insect communities, including pollinator populations which are in pan-European decline. Here, we investigated the benefits of temporarily excluding sheep from pastures on butterfly (Lepidoptera: Rhopalocera and Zygaenidae) and bumblebee (Hymenoptera: Bombidae) communities in two semi-natural grasslands differing in soil fertility and surrounding landscapes. We compared the impact of continuous grazing against rotational grazing (RG) at the same stocking rate but in which a subplot was excluded from the rotation during the main flowering period. We predicted that the diversity of flower-visiting insect community would be improved by RG due to the preservation of flower-rich patches and the maintenance of sward heterogeneity. Benefits of RG management were mainly evidenced on bumblebee density and species richness, with some additional effects on local density of butterflies during the subplot-exclusion period. Temporarily excluding sheep from pastures during peak flowering could thus offer an opportunity to preserve the diversity of flower-visiting insects, in spite of weaker benefits than could have been expected from previous surveys with cattle.     

不同农业景观背景下传粉昆虫群落的分布差异

农业景观中的自然、半自然生境等非农生境可为传粉昆虫提供丰富的食物来源、栖息地、繁殖地、避难所等,对维持生物多样性的稳定起着不可替代的作用。以巩义典型的山地-丘陵-河川混杂的复杂景观和民权的平原农业简单景观为研究区,分析不同景观背景下传粉昆虫群落的物种组成及其在不同生境中的分布特征。结果表明:(1)巩义研究区内累计捕获传粉昆虫18582头,民权研究区内累计捕获传粉昆虫18518头,优势传粉昆虫功能群为双翅目、膜翅目、鞘翅目和鳞翅目等;(2)景观复杂度更高的巩义研究区的传粉昆虫多样性、丰富度以及均匀度均显著高于民权研究区;存在大面积农田斑块的平原景观中则有更多的优势传粉昆虫个体;(3)农田斑块中具有更高的物种丰富度,但林地物种的多样性和均匀度则相对稍高些。农田斑块在作物花期能有效的提高传粉者种群密度,但林地等自然、半自然生境对于维持传粉者多样性和食物缺乏期种群的稳定具有重要作用。因此在未来为确保农业景观中传粉者的多样性与传粉服务的稳定,一方面要关注自然、半自然生境的作用,同时也要考虑不同景观背景下异质性特征对不同生物类群的影响差异。