Entomofauna visitante de Belamcanda chinensis (L.) DC (Iridaceae) durante o período de floração

A study of the reproductive biology of B. chinensis (L.) DC. (Iridaceae) was realized comprising floral biology and breeding systems. The floral biology studies included analyses of nectar production, occurence of osmophores, corolla pigments, ultraviolet reflexion and absortion patterns, viability of pollen, pollinators and flower visitors. The breeding systems were studied taking into account the results of manual pollinators tests. B. chinensis is self-compatible bul cross-pollination is more frequent. The effective pollinators are Plebeia droryana (Friese, 1906) (45,7%), Trigona spinipes (Fabricius, 1793) (27,3%), Tetragonisca angustula (Latreille, 1811) (9,3%). Others insects visitors are considered nectar and pollen thieves. The flowering begins generally in January and February. The complete reproductive cicle, as here considered, begining with floral bud production ending with development of mature fruits, lasts January to June. Seed dispersion is ornitocoric.

ANTI-HERBIVORE PROTECTION BY MUTUALISTIC SPIDERS and THE ROLE of PLANT GLANDULAR TRICHOMES

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The reproductive biology of Cybistax antisyphilitica (Bignoniaceae), a characteristic tree of the South American savannah-like "Cerrado" vegetation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeitos indiretos de predadores e de herbívoros florais e foliares no comportamento de visitantes florais e sucesso reprodutivo de Rubus rosifolius

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo comparativo da diversidade de vespas sociais (Hymenoptera, Vespidae) em mata ciliar e cultura de cana-de-açúcar na região de Ipeúna - SP

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bases para o manejo sustentável de populações silvestres de Heliconia velloziana Emygdio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ecologia da polinização do buriti (Mauritia flexuosa L. – Arecaceae) na restinga de Barreirinhas, Maranhão, Brasil

O estudo das palmeiras nativas é importante por seu grande valor econômico e na manutenção das comunidades de várias espécies de vertebrados e invertebrados que se alimentam de seus frutos, sementes e folhas. A eficiência na produção dos frutos das palmeiras está diretamente relacionada com a presença de insetos polinizadores, principalmente besouros, abelhas e moscas. A palmeira Mauritia flexuosa, comumente conhecida como buriti, é a espécie mais abundante do Brasil e é também chamada de “árvore da vida”, por ser 100% utilizável. Este trabalho teve como objetivo contribuir para o conhecimento da ecologia da polinização do buriti em ambiente de restinga, no município de Barreirinhas, Maranhão, Brasil. Para tanto, obteve-se dados sobre fenologia reprodutiva, biologia floral, sistema reprodutivo e visitantes florais. Para o acompanhamento fenológico foram selecionados 25 indivíduos de cada sexo, os quais foram observados de agosto/2009 a outubro/2012. As fenofases de floração e frutificação foram relacionadas com as variáveis climáticas através de correlação de Spearman. O processo de abertura e longevidade floral foi acompanhado durante o pico de floração da espécie, verificando-se a viabilidade polínica, a receptividade estigmática, as regiões emissoras de odor e a ocorrência de termogênese. Para determinar o sistema reprodutivo foram feitos testes de polinização cruzada e apomixia. O transporte de grãos de pólen pelo vento foi observado, por meio de lâminas de vidros untadas com vaselina que permaneceram penduradas próximas às inflorescências pistiladas durante 24 horas. Os visitantes florais foram coletados através do ensacamento de 20 inflorescências de cada sexo, sendo classificados de acordo com a frequência e o comportamento. O buriti apresentou padrão fenológico anual, sincrônico e sazonal, com floração de agosto a novembro e pico de queda dos frutos em setembro, o que corresponde à estação seca, diferindo do observado na Amazônia, onde estes eventos fenológicos ocorreram na estação chuvosa. Esta diferença pode ser justificada pela grande disponibilidade de água na região, o que faz com que o buriti não necessariamente dependa das chuvas para florescer. Este fato foi evidenciado pela correlação significativa negativa das fenofases com a precipitação e com a umidade relativa. A forte incidência solar e a disponibilidade de água no ambiente contribuíram para o sucesso na floração e frutificação do buriti. Além disto, fatores bióticos podem ter exercido influência no comportamento fenológico, cuja estratégia reprodutiva adotada parece ser a sincronização da floração e da frutificação com a atividade dos polinizadores e dispersores. Dessa maneira a espécie garante a sua reprodução em um período ótimo para a germinação de sementes e estabelecimento de plântulas. O sistema reprodutivo do buriti é xenogâmico. O conjunto de características florais, aliado à abundância de pólen e ao forte odor leva a crer que essa palmeira tenha como principal estratégia de polinização a cantarofilia, porém o vento também possui grande importância na polinização. Além de apresentar polinização do tipo misto (ambofilia), as flores do buriti atraíram uma grande variedade de visitantes, cuja riqueza foi maior que a observada na Amazônia.

Comparative reproductive biology of two Florida pawpaws Asimina reticulata Chapman and Asimina tetramera Small

I investigated the phenology and breeding systems of two Florida endemic pawpaws, Asimina reticulata, widespread in peninsular Florida, and A. tetramera, a federally endangered species limited to two counties on the Atlantic Coastal Ridge. The purpose of this study was to determine if differences contribute to the rarity of Asimina tetramera compared with A. reticulata. The study was conducted in sand pine scrub sites with the largest populations of A. tetramera in the two counties. Flowering seasons differ for the two species. Both species are hermaphroditic and strongly protogynous. Pollination experiments show that neither species is autogamous and the primary breeding mechanism is outcrossing, although low levels of geitonogamous pollination occur in mature scrub habitats. High levels of inbreeding depression were noted in both species at both sites but inbreeding depression was relaxed the first year post-fire. Fruit set in mature habitats may be pollinator limited. ^ I studied insects associated with the flowers in sand pine scrub habitat in southeastern Florida from 1994–1996. The most commonly represented orders were Coleoptera (25 spp.), Lepidoptera. (3 spp.) and Hymenoptera. (3 spp.). All Coleoptera. were flower visitors; one species, Euphoria sepulchralis (Fabricius)(Scarabeaidae), visited flowers of the two Asimina species at both sites. Eurytides marcellus (Cramer) (Lepidoptera: Papilionidae) eggs and larvae were observed on both species of Asimina during each year of the study. ^ Resource management techniques were applied to a mature sand pine scrub community in Jonathan Dickinson State Park in southeastern Florida for the management of Asimina tetramera. Manipulations conducted in 1996 included combinations of fire and mechanical treatments. I measured effects of these treatments on flowering and fruit set on A. tetramera and found cutting and burning was most effective in increasing flowering, followed by burning. Mechanical cutting and mulching had no significant effect. ^

Structure of bee-flower system in the coastal sand dune of Abaeté, northeastern Brazil

For twelve months (from January to December of 1996) we investigated bee-flower interactions in a sea coastal ecosystem in Bahia, Brazil. Samples were taken three times each month. 3983 individuals belonging to 49 bee species, grouped in 13 morph-functional categories, visited 66 plant species belonging to 39 botanic families. It was observed 310 interactions between bees and plants at species level. The use of floral resources by bees was not homogeneous; most of the plant species received a low number of visitors. No restricted plant-bee species relationship in resource use concerning the subset of analyzed interactions was detected. In Abaeté the generalist relationships predominated.

The impact of an insecticide on insect flower visitation and pollination in an agricultural landscape

1 Pesticides are considered a threat to pollinators but little is known about the potential impacts of their widespread use on pollinators. Less still is known about the impacts on pollination, comprising the ecosystem service that pollinators provide to wildflowers and crops. 2 The present study measured flower visitation and pollination in an agricultural landscape, by placing potted flowering plants (Petunia sp.) in vine fields sprayed with a highly toxic insecticide (fenitrothion). During two sampling rounds, insect visitors to the petunias were observed and measures of pollination were recorded by counting and weighing seeds. 3 In the earlier sampling round, a lower species richness of insect visitors was observed in fields that had received an early application of insecticide. No negative impacts were found from later applications. The results obtained suggest a greater potential harm to insect pollinators and flower visitation as a result of insecticide application early in the season. 4 No reduction in pollination was found in fields that received an early insecticide application. Pollination was greater with two insecticide applications between sampling rounds rather than one application. 5 In the present study system, insecticide application had a negative effect on pollinators but a possible positive effect on pollination services. In some cases, it may be that actions for conserving biodiversity will not benefit pollination services to all plants.

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.

Nectar Robbery By A Hermit Hummingbird: Association To Floral Phenotype And Its Influence On Flowers And Network Structure.

Interactions between flowers and their visitors span the spectrum from mutualism to antagonism. The literature is rich in studies focusing on mutualism, but nectar robbery has mostly been investigated using phytocentric approaches focused on only a few plant species. To fill this gap, we studied the interactions between a nectar-robbing hermit hummingbird, Phaethornis ruber, and the array of flowers it visits. First, based on a literature review of the interactions involving  P. ruber, we characterized the association of floral larceny to floral phenotype. We then experimentally examined the effects of nectar robbing on nectar standing crop and number of visits of the pollinators to the flowers of Canna paniculata. Finally, we asked whether the incorporation of illegitimate interactions into the analysis affects plant-hummingbird network structure. We identified 97 plant species visited by P. ruber and found that P. ruber engaged in floral larceny in almost 30 % of these species. Nectar robbery was especially common in flowers with longer corolla. In terms of the effect on C. paniculata, the depletion of nectar due to robbery by P. ruber was associated with decreased visitation rates of legitimate pollinators. At the community level, the inclusion of the illegitimate visits of P. ruber resulted in modifications of how modules within the network were organized, notably giving rise to a new module consisting of P. ruber and mostly robbed flowers. However, although illegitimate visits constituted approximately 9 % of all interactions in the network, changes in nestedness, modularity, and network-level specialization were minor. Our results indicate that although a flower robber may have a strong effect on the pollination of a particular plant species, the inclusion of its illegitimate interactions has limited capacity to change overall network structure.

A Morphological and Histological Characterization of Bisexual and Male Flower Types in Pomegranate

Pomegranate [Punica granatum (Punicaceae)] is characterized by having two types of flowers on the same tree: hermaphroditic bisexual flowers and functionally male flowers. This condition, defined as functional andromonoecy, can result in decreased yields resulting from the inability of male flowers to set fruit. Morphological and histological analyses of bisexual and male flowers were conducted using light and scanning electron microscopy (SEM) to characterize the different flower types observed in pomegranate plants and to better understand their developmental differences. Bisexual flowers had a discoid stigma covered with copious exudate, elongated stigmatic papillae, a single elongate style, and numerous stamens inserted on the inner wall of the calyx tube. Using fluorescence staining, high numbers of pollen tubes were observed growing through a central stylar canal. Ovules were numerous, elliptical, and anatropous. In contrast, male flowers had reduced female parts and exhibited shortened pistils of variable heights. Stigmatic papillae of male flowers had little exudate yet supported pollen germination. However, pollen tubes were rarely observed in styles. Ovules in male flowers were rudimentary and exhibited various stages of degeneration. Pollen from both types of flowers was of similar size, approximate to 20 mu m, and exhibited similar percent germination using in vitro germination assays. Pollen germination was strongly influenced by temperature. Maximal germination (greater than 74%) was obtained at 25 and 35 degrees C; pollen germination was significantly lower at 15 degrees C (58%) and 5 degrees C (10%).

Characterization of unisexual flower development in the endangered mahogany tree Swietenia macrophylla King. (Meliaceae)

The selection of candidate plus trees of desirable phenotypes from tropical forest trees and the rapid devastation of the natural environments in which these trees are found have created the need for a more detailed knowledge of the floral and reproductive biology of tropical tree species. In this article, the organogenic processes related to unisexual flower development in tropical mahogany, Swietenia macrophylla, are described. Mahogany inflorescences at different developmental stages were evaluated using scanning electron microscopy or optical microscopy of histological sections. The unisexual flowers of S. macrophylla are usually formed in a thyrse, in which the positions of the female and male flowers are not random. Differences between male and female flowers arise late during development. Both female and male flowers can only be structurally distinguished after stage 9, where ovule primordia development is arrested in male flowers and microspore development is aborted in female flower anthers. After this stage, male and female flowers can be distinguished by the naked eye as a result of differences in the dimensions of the gynoecium. The floral characteristics of S. macrophylla (distribution of male and female flowers within the inflorescence, and the relative number of male to female flowers) have practical implications for conservation strategies of this endangered species. (c) 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156, 529-535.