Abundance Of Flower Visitors Research Articles

EDITOR'S CHOICE: REVIEW: Trait matching of flower visitors and crops predicts fruit set better than trait diversity

Summary Understanding the relationships between trait diversity, species diversity and ecosystem functioning is essential for sustainable management. For functions comprising two trophic levels, trait matching between interacting partners should also drive functioning. However, the predictive ability of trait diversity and matching is unclear for most functions, particularly for crop pollination, where interacting partners did not necessarily co‐evolve. World‐wide, we collected data on traits of flower visitors and crops, visitation rates to crop flowers per insect species and fruit set in 469 fields of 33 crop systems. Through hierarchical mixed‐effects models, we tested whether flower visitor trait diversity and/or trait matching between flower visitors and crops improve the prediction of crop fruit set (functioning) beyond flower visitor species diversity and abundance. Flower visitor trait diversity was positively related to fruit set, but surprisingly did not explain more variation than flower visitor species diversity. The best prediction of fruit set was obtained by matching traits of flower visitors (body size and mouthpart length) and crops (nectar accessibility of flowers) in addition to flower visitor abundance, species richness and species evenness. Fruit set increased with species richness, and more so in assemblages with high evenness, indicating that additional species of flower visitors contribute more to crop pollination when species abundances are similar. Synthesis and applications. Despite contrasting floral traits for crops world‐wide, only the abundance of a few pollinator species is commonly managed for greater yield. Our results suggest that the identification and enhancement of pollinator species with traits matching those of the focal crop, as well as the enhancement of pollinator richness and evenness, will increase crop yield beyond current practices. Furthermore, we show that field practitioners can predict and manage agroecosystems for pollination services based on knowledge of just a few traits that are known for a wide range of flower visitor species.

Alpha and beta diversity of bees and their pollination role onCucurbita pepoL. (Cucurbitaceae) in the Guatemalan cloud forest

Abstract. Cucurbita pepo L. (Cucurbitaceae) was an integral component of the diet of Pre-Columbian Mesoamerican cultures and is an important cash crop with high cultural value in contemporaneous indigenous populations of Guatemala. Despite the increasing attention to native bees as pollinators of cucurbit crops, little is known about the diversity of bees that visit or pollinate these crops in many regions. Based on collections from 11 observational plots of C. pepo established in five localities and maintained by the local community across the Cloud Forest Corridor in Guatemala, we documented 27 bee species belonging to 14 genera in Apidae and Halictidae as floral visitors. Species composition was significantly different among plots and among localities; however, honey bees (Apis mellifera Linnaeus, 1758) (Apidae: Apini) and the stingless bee Partamona bilineata (Say, 1837) (Apidae: Meliponini) were the most abundant flower visitors in all plots and localities, accounting up to 80% of the total number of...

Where is the UK's pollinator biodiversity? The importance of urban areas for flower-visiting insects.

Insect pollinators provide a crucial ecosystem service, but are under threat. Urban areas could be important for pollinators, though their value relative to other habitats is poorly known. We compared pollinator communities using quantified flower-visitation networks in 36 sites (each 1 km2) in three landscapes: urban, farmland and nature reserves. Overall, flower-visitor abundance and species richness did not differ significantly between the three landscape types. Bee abundance did not differ between landscapes, but bee species richness was higher in urban areas than farmland. Hoverfly abundance was higher in farmland and nature reserves than urban sites, but species richness did not differ significantly. While urban pollinator assemblages were more homogeneous across space than those in farmland or nature reserves, there was no significant difference in the numbers of rarer species between the three landscapes. Network-level specialization was higher in farmland than urban sites. Relative to other habitats, urban visitors foraged from a greater number of plant species (higher generality) but also visited a lower proportion of available plant species (higher specialization), both possibly driven by higher urban plant richness. Urban areas are growing, and improving their value for pollinators should be part of any national strategy to conserve and restore pollinators.

Shorter flowering seasons and declining abundance of flower visitors in a warmer Arctic

Climate-induced changes in phenology have the potential to push trophic relationships out of synchrony, but evidence of this phenomenon is scant, particularly in the Arctic. A long-term (1996–2009), spatially replicated data set from high-Arctic Greenland now indicates a climate-associated shortening of the flowering season, and a concomitant decline in flower visitor abundance.

Assemblage of flower visitors to Dillenia suffruticosa and possible negative effects of disturbances in Sarawak, Malaysia

AbstractDillenia suffruticosa (Dilleniaceae), a common pioneer shrub in Southeast Asia, is broadly distributed along roadsides. This species flowers throughout the year and is thought to be a keystone species for maintaining populations of flower visitors. To examine the flower visitors of this species, we conducted field surveys and described the behaviors of each flower visitor species within four different research sites: Primary Forests 1 and 2, Secondary Forest, and Mixed Vegetation. We caught 1087 individuals belonging to 51 species from 11 insect families and one species of arachnid. Most flower visitors belonged to Hymenoptera (98.6% of individuals); Trigona spp. and Xylocopa spp. (Apidae) accounted for 64.0% and 20.0%, respectively, of all caught individuals. According to observations of behavior by each species, effective pollinators may include Xylocopa spp. and Amegilla spp. (Apidae). We compared the research results among four research sites and found that the effective pollinators were not different among sites. However, the number of species and the abundances of flower visitors decreased in disturbed areas, especially in Secondary Forest. This research suggests the effects of human disturbances on the diversity and abundance of flower visitors.

How do plant communities and flower visitors relate? A case study of semi-natural xerothermic grasslands

<p>The paper examines the relationships between the species composition of flower visitors and plants in the semi-natural xerothermic grasslands in southern and central Poland. Thirty 10 × 10 m permanent plots were laid out in total, mainly in nature reserves. The vegetation units studied were classified according to the Braun-Blanquet system; these were phytocoenoses of the <em>Festuco-Brometea</em> classes <em>Inuletum ensifoliae</em>, <em>Adonido-Brachypodietum pinnati</em> and the transitional plant community. Entomological research was performed using the Pollard method within the same plots. A particular site was visited only once and different sites were studied between April and August 2008. We applied, among others, co-correspondence-analysis Co-CA, detrended correspondence analysis (DCA) and redundancy analysis (RDA) to investigate the co-occurrence patterns of plants and flower visitors and their biotopic requirements. We found that the species composition of flower visitors cannot be predicted by floristic composition when the duration of the study is restricted to one day (but under similar weather conditions); however, there is a positive relationship between the species richness of insects and plants and a positive relationship between the number of plant species and the abundance of flower visitors. The Ellenberg moisture index and the cover of meadow species significantly explained the species composition of insects. The three various vegetation units and five dominant xerothermic species, i.e. <em>Adonis vernalis</em>, <em>Anemone sylvestris</em>, <em>Inula ensifolia</em>, <em>Linum hirsutum</em> and <em>Carlina onopordifolia</em> that were studied across time differed in the species richness of insects. Our results demonstrate that possible patterns in the species composition and the assembly rules of flower visitors are not apparent when the Pollard method is applied. Based on the data obtained using this method, the flower visiting assemblages seem not to be driven by competition and they primarily show a tendency to co-occur which can be an artifact. A plant-focused method that included a rarefaction analysis yielded more insightful results and shed more light on the differences between the dominant plants that shape the physiognomy of plant communities in a possible pollination specialization.</p>

Creating patches of native flowers facilitates crop pollination in large agricultural fields: mango as a case study

Summary As cropland increases, fields become progressively isolated from pollinators, leading to declines in pollinator‐dependent crop productivity. With the rise in demand for pollinator‐dependent foods, such productivity losses may accelerate conversion of natural areas to cropland. Pollination–compensation measures involving managed pollinators or hand pollination are not always optimal or are too costly. Introducing areas of native vegetation within cropland has been proposed as a way to supplement crop pollinators, but this measure is perceived by farmers to carry costs outweighing benefits to agricultural production. Studies quantifying benefits of small patches of native flowers to crop pollination are therefore necessary to encourage such practices. To ascertain whether provision of floral resources within farmlands can facilitate pollination, and hence, crop yields, small experimental patches of perennial native plants (native flower compensation areas, NFCAs) were created in nonproductive areas of large commercial fields of several cultivars of mango Mangifera indica. Pesticide use and isolation from natural habitat were associated with declines in flying visitors and in mango production (kg of marketable fresh fruit), but presence of NFCAs ameliorated these declines, and NFCAs did not harbour any mango pests. In areas far from natural vegetation, orchards near NFCAs had significantly higher diversity and abundance of mango flying visitors, as well as mango production, than orchards far from NFCAs, although these measures were still lower than in orchards close to natural areas. Neither the most abundant flower visitors to mango (ants) nor initial fruit set was significantly affected by distance, pesticides or NFCAs, suggesting that although fertilization is associated with factors unaffected by isolation from natural habitat and pesticide use (i.e. self‐ and ant‐pollination), viable fruit set (and ultimately, production) requires cross‐pollination, for which flying visitors are essential. Synthesis and applications. Our results show that the presence of small patches of native flowers within large farms can increase pollinator‐dependent crop production if combined with preservation of remaining fragments of natural habitat and judicious use of pesticides. Native flower compensation areas represent a profitable management measure for farmers, increasing cost‐effectiveness of cropland while indirectly contributing to preservation of natural habitat.

Temporal variation of flower scent in Silene otites (Caryophyllaceae): a species with a mixed pollination system

Floral scent composition and emission are often related to olfactory abilities, preferences and activity times of pollinating agents. However, most studies have focused on species with one pollinator type, and little is known about species with mixed pollination systems. We investigated the temporal variation in flower visitor activity and flower scent emission of Silene otites (Caryophyllaceae), a species regarded as being nocturnal and pollinated by moths and mosquitoes. We found, however, that S. otites is not only visited at night by moths and mosquitoes, but also by a wide range of day-active insects. Furthermore, both the intensity and composition of floral scent change during the course of the day. Total scent emission reached its maximum in the early hours of the night when compounds known to be attractants for moths and/or mosquitoes, such as lilac aldehyde, benzaldehyde, phenylacetaldehyde and 2-phenylethanol, dominated the scent. However, although less intensive, emission continued during the day. In the early morning, α-pinene, hotrienol, 2-phenylethanol and δ-3-carene were the dominant scent compounds. (E)-β-Ocimene, hotrienol and benzyl alcohol contributed proportions of at least 10% before midday when flies, such as syrphids, were abundant flower visitors, whereas linalool and hotrienol contributed to the scent with at least 10% each in the afternoon when bees also contributed to flower visits. We conclude that, in S. otites, the changing emission patterns are ‘in tune’ with the olfactory abilities, preferences and activity times of its day- and night-active potentially pollinating flower visitors. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169, 447–460.

Ecological consequences of dead wood extraction in an arid ecosystem

Coarse woody debris (CWD) plays a key role in ecosystems, reducing erosion and affecting soil development, storing nutrients and water, providing a major source of energy and nutrients, serving as a seedbed for plants and as habitat for decomposers and heterotrophs. We asked whether removal of CWD affected the structure and functioning of an arid woodland ecosystem in mid-western Argentina. These woodlands are protected by national laws and inhabited by indigenous local pastoralists who have land rights to use natural resources, including wood for fuel and construction material. We hypothesized that removal of CWD affected negatively the populations of wood-nesting pollinators, the reproductive performance of Prosopis flexuosa (the dominant tree species), plant cover, richness and composition, and nutrient cycling in the soil. We conducted a manipulative experiment consisting of four pairs of 70 m radius circular plots, each pair with an experimental (CWD removal) and a control (no removal) plots. Experimental CWD extraction affected negatively flower visitor abundance, although the magnitude of this effect decreased over time. In contrast, extraction had a significant, positive effect on seed production of P. flexuosa. No significant effects of extraction were found on cover, richness and composition of understory plants and soil properties. Thus, CWD did not have the generally negative effects expected under our hypotheses.

Influence of reproductive traits on pollination success in two Daphne species (Thymelaeaceae)

Taxonomically related species can differ in a number of reproductive traits, which may translate into a differential mating system and pollination success. Here we compare two hermaphroditic insect-pollinated Daphne species (D. rodriguezii and D. gnidium) which differ in distribution (island endemic vs. mediterranean) and floral traits (long- vs. short-tube corolla). We investigated their mating system and pollen limitation by means of hand-pollination experiments and quantified the diversity and abundance of flower visitors by direct observations. Plant size and five reproductive traits (flower production, proportion of viable anthers, pollen production, flower tube length and tepal area) were studied to assess how they contribute to reproductive success, measured as proportion of pollen grains germinated per stigma and fruit set. Selfing was very low and pollen limitation existed in both species, though was higher in D. rodriguezii probably due to the scarcity of flower visitors. The low fruit set in both species suggests that most of the pollen grains found on stigmas are self-pollen. Pollinators appeared to favour some floral traits (specifically, flower tube length or tepal area) in both species, although flower crop in D. rodriguezii was the only reproductive trait influencing fruit set. In both species, the highest variability in reproductive traits and pollination success was within individuals. Our findings suggest that despite both species showed similar mating system, dependency on outcrossing pollen and selection of floral traits, pollen limitation was higher in D. rodriguezii, probably as a higher proportion of self-pollen arrives to its stigmas.

Non-additive effects of genotypic diversity increase floral abundance and abundance of floral visitors.

BackgroundIn the emerging field of community and ecosystem genetics, genetic variation and diversity in dominant plant species have been shown to play fundamental roles in maintaining biodiversity and ecosystem function. However, the importance of intraspecific genetic variation and diversity to floral abundance and pollinator visitation has received little attention.Methodology/Principal FindingsUsing an experimental common garden that manipulated genotypic diversity (the number of distinct genotypes per plot) of Solidago altissima, we document that genotypic diversity of a dominant plant can indirectly influence flower visitor abundance. Across two years, we found that 1) plant genotype explained 45% and 92% of the variation in flower visitor abundance in 2007 and 2008, respectively; and 2) plant genotypic diversity had a positive and non-additive effect on floral abundance and the abundance of flower visitors, as plots established with multiple genotypes produced 25% more flowers and received 45% more flower visits than would be expected under an additive model.Conclusions/SignificanceThese results provide evidence that declines in genotypic diversity may be an important but little considered factor for understanding plant-pollinator dynamics, with implications for the global decline in pollinators due to reduced plant diversity in both agricultural and natural ecosystems.

Foraging behaviour of Apis florea F., an important pollinator of Allium cepa L.

SummaryThe foraging behaviour of insect visitors to onion (Allium cepa L.) flowers was studied in relation to five environmental variables. The dwarf honey bee Apis florea L. was the most abundant flower visitor, and comprised more than 94% of the total visitors. Commencement of flight activity occurred when a minimum threshold of environmental variables was exceeded, while the cessation was governed mainly by decline in light intensity and radiation. The foraging population correlated significantly and positively with air temperature, light intensity, solar radiation and nectar-sugar concentration and negatively with relative humidity. Path coefficient analysis, revealed, however, that the direct effect of temperature was large and positive followed by light intensity and solar radiation while the direct effect of relative humidity was small and negative. The direct effect of nectar-sugar concentration was positive and negligible. Path coefficient analysis thus gave a clearer picture of the effects than did a simple correlation analysis. On average A. florea visited 1.33±0.26 and 6.17±0.58 umbels and flowers/min, during different hours of the day. The insect pollinated plots produced significantly more seeds with heavier weights than those isolated from insect visits.

A new pollination system: brood-site pollination by flower bugs in Macaranga (Euphorbiaceae)

Macaranga (Euphorbiaceae) is a large genus of dioecious trees with approx. 260 species. To date, only one pollination study of the genus has reported brood-site pollination by thrips in M. hullettii. In this study, the pollination system of Macaranga tanarius is reported. The study was conducted on Okinawa and Amami Islands, Japan. Flower visitors on M. tanarius were collected and their pollen load and behaviour on the flowers examined, as well as inflorescence structure and reward for the pollinators. The most abundant flower visitors found on the male and female inflorescences were Orius atratus (Anthocoridae, Hemiptera), followed by Decomioides schneirlai (Miridae, Hemiptera). Pollen load on O. atratus from flowering pistillate inflorescences was detected as well as from staminate flowers. Orius atratus and D. schneirlai are likely to use the enclosed chambers formed by floral bracts as breeding sites before and during flower anthesis, and feed on nectar on the adaxial surface of flower bracts. The extrafloral nectary has a ball-shaped structure and the contained nectar is not exposed; the hemipterans pierce the ball to suck out the nectar. The results indicate that the plant is pollinated by flower bugs breeding on the inflorescences. This study may be the first report of pollination systems in which flower bugs are the main pollinators. Similarity of pollination systems between M. hullettii and M. tanarius indicates that the two brood-site pollination systems have the same origin. The pollinator species belongs to a predacious group, whose major prey includes thrips. The pollination system might represent a unique example of evolution from predatory flower visitors feeding on the pollinators (thrips) to the main pollinators.

Effects of fragmentation on pollinator abundance and fruit set of an abundant understory palm in a Mexican tropical forest

Tropical forest fragmentation affects both biodiversity and plant reproductive success when small, isolated fragments sustain a reduced diversity or abundance of pollinators. Fragmentation-related effects have been poorly investigated in the case of palms, an important structural and functional component of tropical forests. We examined the relationships between fragment size and diversity and abundance of flower visitors, and palm reproduction, by quantifying the arthropod fauna associated to inflorescences of the palm Astrocaryum mexicanum, and its fruit set, in fragments of different size. The sample yielded a total of 228,772 arthropods (10 orders, 60 species). Coleoptera was the predominant group (⩾50% of the species), followed by Hymenoptera (20%), while the remaining (30%) was distributed among the other eight orders. We found a predominance of pollinating insects (Coleoptera-Nitidulidae), representing 85% of all visitors. Pollinator abundance was negatively affected by fragmentation, with a 4.2-fold average difference between small (<35 ha) and large (114–700 ha) fragments. However, fruit set was relatively high (⩾0.7) and not affected by fragmentation during three reproductive seasons. This could be explained because small fragments retained remarkably high numbers of pollinators (1191.4/inflorescence) and by the high abundance of palms (and flowers) in fragments. Further research is needed, however, to assess if fragmentation restricts pollinator movements to plants within the fragments, leading to a reduction in genetic variation of the progeny present in forest remnants.

Pollination in small islands by occasional visitors: the case of Daucus carota subsp. commutatus (Apiaceae) in the Columbretes archipelago, Spain

This study investigates the pollination ecology and related floral traits of the species Daucus carota subsp. commutatus in the isolated archipelago of Columbretes, E. Spain, where bees are absent. Two populations were studied: a small population found on a relatively large island (Grossa) inhabited nowadays by three people; and a larger population on a smaller uninhabited island (Foradada). The plant, found also in other rocky coastal enclaves of the west Mediterranean, is totally self-compatible, andromonoecious, exhibiting strong protandrous dichogamy and sequential flowering of umbel orders, with limited probability of self pollination at the plant level. Pollination on both study islands is carried out solely by flies, mainly by Eristalis tenax (Syrphidae), a long distance visitor and efficient pollinator, but irregular migrant to the archipelago; and Lucilia sericata (Calliphoridae), an abundant flower visitor but less efficient pollinator dependent on human and avian wastes for its larval growth. The small population on Grossa appears not to suffer pollen limitation. Seed set is reduced, however, in the large population on Foradada, which we attribute to the low pollinator capital of this island, which is too small to attract and sustain migrant hoverflies and where no human and avian wastes are available to sustain blowfly growth. We conclude that in isolated environments with reduced or unpredictable pollinator capital, long distance migrant pollinators, such as E. tenax, play an invaluable conservation and perhaps evolutionary role for the native plants. Because these islands have been always practically uninhabited we argue that the absence of adequate local pollinator capital is perhaps compensated by the selection of particular floral traits, which differentiate the study subspecies from other conspecifics. Such traits are: the exposure of nectar during male versus female stage to enhance quick pollen flow; the extended stigma receptivity period (up to 10 days) resulting in a total flower life span of up to 22 days, enabling an adequate pollen deposition on stigmas even under low pollen transfer rates. In this respect, the low flower sex ratio (hermaphrodite: staminate) compared to other conspecifics studied elsewhere may be also relevant.

The importance of monkey beetle (Scarabaeidae: Hopliini) pollination for Aizoaceae and Asteraceae in grazed and ungrazed areas at Paulshoek, Succulent Karoo, South Africa

The relative importance of monkey beetles (Hopliini, Scarabeidae) as pollinators of Asteraceae and Aizoaceae in the Succulent Karoo as well as the influence of livestock grazing on their abundance and diversity was investigated. Hopliine beetles proved to be the, or among the, most abundant flower visitors of 12 investigated plant species. However, during single flower observations at three Aizoaceae species, bees (Apoidea), bee flies (Bombyliidae) and pollen wasps (Masaridae) were the most frequent flower visitors. However, monkey beetles carried the highest Asteraceae and Aizoaceae pollen loads, and are therefore considered to play a vital role in the pollination of these two families. Abundance, species richness and diversity of Hopliini did not appear to be heavily affected by livestock grazing. Annual variation in the composition of monkey beetle populations was more dramatic. Still, some species showed higher abundances on heavily grazed rangeland while others only occurred under low grazing pressure. It is presumed that changes in the composition of the vegetation, especially the observed decrease of perennial plants in favour of annuals and geophytes (Todd and Hoffman 1999) could in turn affect the composition of monkey beetle assemblages.

Relationships between the density and diversity of floral resources and flower visitor activity in a temperate grassland community

Abstract 1. Does the diversity and abundance of one trophic level affect another? Several studies at the landscape level have found a positive relationship between the diversity of floral resources and the diversity and abundance of pollinators. However, little is known about the relationship between these trophic levels on a smaller spatial scale, and the importance of blossom density relative to plant species richness in predicting abundance and richness of different flower visitor groups.2. This study used a small‐scale approach to investigate how, and if, the diversity and abundance of floral resources in study plots affected the visitation activity of different flower visitor groups. During 201 observation periods between late May and mid‐August 2003, 3682 visits were observed. Bumblebees (60%), muscoids (17%), syrphids (9%), and beetles (5%) were the most abundant flower visitors.3. Regression analysis was used to investigate the relationship between blossom density and plant species richness with visitation activity, including the probability of presence in plots, the visits within plots, and the visitor richness of the most abundant pollinator groups.4. The activity of beetles, bumblebees, and muscoids was positively predicted by the variation in blossom density, while syrphid activity was better predicted by plant species richness. Overall, the models for beetles and bumblebees explained much more of the variation in activity compared with the models for the dipterans, and blossom density was a better predictor of both flower visitor richness and activity than was plant species richness.

Pollination mutualism between a new species of the genus Colocasiomyia de Meijere (Diptera: Drosophilidae) and Steudnera colocasiifolia (Araceae) in Yunnan, China

AbstractA new species of the genus Colocasiomyia de Meijere (Diptera: Drosophilidae) was discovered from inflorescences of Steudnera colocasiifolia K. Koch (Araceae) in Yunnan, China. The new species is described as Colocasiomyia steudnerae Takenaka and Toda, sp. nov., and we investigated the reproductive ecology of both the fly and the plant species. This fly species reproduces in the inflorescences/infructescences of the plant, and depends almost throughout its entire life cycle on the host plant. The fly species is the most abundant flower visitor for S. colocasiifolia and behaves intimately with the flowering events, suggesting that it is the unique and most efficient pollinator for the host plant. Bagging (insect‐exclusion) treatment of inflorescences resulted in no fruits. These findings strongly suggest that intimate pollination mutualism has evolved between the fly and the host plant, as are known in other Colocasiomyia flies and Araceae plants. One notable feature of this system is that the new species almost monopolizes the host‐plant inflorescence as a visitor, without any cohabiting Colocasiomyia species. In comparison to other cases where two Colocasiomyia species share the same inflorescence and infructescence of Araceae host plants for reproduction by separating their breeding niches microallopatrically between the staminate (upper male‐flower) and the pistillate (lower female‐flower) regions on the spadix, C. steudnerae exhibits a mixture of stamenicolous and pistillicolous breeding habits.

Factors influencing flight activity of Apis florea F, an important pollinator of Daucus carota L

SummaryForaging ecology of insect pollinators visiting carrot flowers (Daucus carota L.) was studied in relation to five environmental variables. The dwarf honeybee Apis florea L. was the most abundant flower visitor and comprised more than 94% of flower visiting insects. Commencement of flight activity occurred when a minimum threshold of environmental variables was surpassed, while cessation was governed mainly by declining values of light intensity and radiation. In between commencement and cessation, the foraging population correlated significantly and positively with air temperature, light intensity, solar radiation and nectar-sugar concentration and negatively with relative humidity. Path coefficient analysis, however, revealed that the direct effect of temperature was high and positive followed by light intensity and solar radiation while the direct effect of relative humidity was high and negative. The direct effect of nectar-sugar concentration was negative and negligible. Path coefficient analysis gave a more comprehensive picture of effects than did simple correlation analysis. Apis florea on average visited 1.14 ∀ 0.23 and 22.78 ∀ 2.57 umbels and flowers/min, respectively, during different hours of the day. Furthermore, the insect pollinated plots produced significantly more seeds with heavier weights than those isolated from insect visits.

Colonization of Nishino-shima Island by Plants and Arthropods 31 Years after Eruption

Although many researchers have studied colonization, the process has rarely been observed on newly emerged oceanic islands. To describe the colonization process of a remote oceanic island, I investigated the flora, vegetation, and pollinators of Nishino-shima Island 31 yr after a major eruption in 1973. Nishino-shima Island, which is 22 ha in size, is located 1,000 km south of mainland Japan. Vegetation cover had increased, especially on new lowland area, since a preliminary survey done 10 yr after the eruption, but plant species richness remained poor (only six species). Thus, the plant colonization rate (0.10 species/yr) was far slower than that of other volcanic islands such as Krakatau. Most plants (four species) had ocean-dispersed seeds, but two species were likely dispersed via attachment to seabirds. Despite colonization by only a few plant species, there were abundant flower visitors including ants, bugs, a butterfly, and a fly ( but no bee species), and the average visitation rate per flower was 5.5 visits/12 hr in total observations. Most of the insects used multiple food sources, concurrently acting as scavengers or herbivores.