Bees are the most important diurnal pollinators of angiosperms. In several groups of bees a nocturnal/crepuscular habit developed, yet little is known about their role in pollination and whether some plants are adapted specifically to these bees. We used a multidisciplinary approach to investigate the reproductive biology and to understand the role of nocturnal/crepuscular bees in pollination of Campomanesia phaea (Myrtaceae), popularly named cambuci. We studied the floral biology and breeding system of C. phaea. We collected the floral visitors and tested the pollinators' effectiveness. We also determined the floral scents released at night and during daytime, and studied behavioural responses of crepuscular/nocturnal bees towards these scents. The flowers of cambuci were self-incompatible and had pollen as the only resource for flower visitors. Anthesis lasted around 14 h, beginning at 04:30 h at night. The flowers released 14 volatile compounds, mainly aliphatic and aromatic compounds. We collected 52 species of floral visitors, mainly bees. Nocturnal and crepuscular bees (four species) were among the most frequent species and the only effective pollinators. In field bioassays performed at night, nocturnal/crepuscular bees were attracted by a synthetic scent blend consisting of the six most abundant compounds. This study describes the first scent-mediated pollination system between a plant and its nocturnal bee pollinators. Further, C. phaea has several floral traits that do not allow classification into other nocturnal pollination syndromes (e.g. pollinator attraction already before sunrise, with pollen as the only reward), instead it is a plant specifically adapted to nocturnal bees.

-(Floral resources used by insects in a grassland community in Southern Brazil). The goal of the present study was to identify plant species used as food source, the floral resources utilized, and the insects that visit flowers in a grassland community in southern Brazil. The study was carried out in an area of one hectare, located in a grassland formation in the Parque Estadual de Itapuã, State of Rio Grande do Sul, Brazil. The flowering pattern was seasonal, and richness and abundance of insects was higher during the period of high resource availability. Flowers of 106 species of angiosperms (73 genera and 34 families) were used as source of floral resources for 219 species (2,767 specimens) of insects. A total of 91.5% of plant species were visited by bees, 53.8% by flies, 34.9% by wasps, 22.6% by butterflies, and 12.3% by beetles. Nectar was the main resource consumed by the visitors (41.1%). Asteraceae was the richest (38 spp.) and most visited family, with 63.1% of the species and 49.5% of all specimens of recorded insects. Bees were the most representative insects (33.2% spp., 65% indiv.), followed by flies (26.9% spp., 16.5% indiv.), wasps, butterflies and beetles. 40 plant species were considered important resources for the floral visitors' community, due to high number of, both, species and individuals recorded in their flowers. The family Asteraceae as a species set was the main floral resource used by insect visitors through the year and has great importance for the maintenance of populations of many species of bees, flies, wasps and butterflies in the studied area.Key words -anthophilous insects, Asteraceae, community ecology, floral resources, floral visitors RESUMO -(Recursos florais utilizados por insetos em uma comunidade campestre no sul do Brasil). O objetivo deste trabalho foi identificar as espécies vegetais utilizadas como fontes de alimento, os recursos florais utilizados e os insetos visitantes das flores em uma comunidade campestre no sul do Brasil. O estudo foi realizado em uma parcela de um hectare, alocada em uma formação campestre no Parque Estadual de Itapuã, RS. O padrão de floração foi sazonal e a riqueza e abundância de insetos, maior no período de mais oferta de recursos. Flores de 106 espécies de angiospermas (73 gêneros e 34 famílias) foram utilizadas como fontes de recursos florais para 219 espécies e 2.767 espécimes de insetos. 91,5% das espécies vegetais foram visitadas por abelhas, 53,8% por moscas, 34,9% por vespas, 22,6% por borboletas e 12,3% por besouros. Néctar foi o principal recurso consumido pelos visitantes (41,1%). Asteraceae foi a família mais rica (38 spp.) e a mais visitada, com 63,1% das espécies e 49,5% de todos os espécimes de insetos registrados. Espécies com numerosas flores agrupadas em inflorescências e com recursos florais acessíveis foram as mais visitadas, por espécies e indivíduos de visitantes florais. Abelhas foram os insetos mais representativos (33,2% spp., 65% indiv.), seguidas de moscas (26,9% spp., 16,5% indiv.), vespas, borboletas e...

Abstract:The study of plant-pollinator interactions is a major tool for conservation biology of fragmented habitats like the Atlantic Rain Forest and for the study of evolutionary traits that rule these interactions. Information on reproductive biology and floral visitor interactions of Sophora tomentosa and Crotalaria vitellina (Fabaceae) is presented in this study. Both species are common in the restinga formation of the Atlantic Rain Forest in the Núcleo Picinguaba, Parque Estadual da Serra do Mar, Ubatuba -São Paulo. These species occur in the same areas, the flowering period is the same for both and they have yellow flowers that offer nectar as the major reward. Both are self-compatible, although fruit and seed set depend on the pollinators. Xylocopa brasilianorum and Megachile sp.1 were pollinators of S. tomentosa, whereas C. vitellina was pollinated by both the aforementioned bees and Bombus morio, Centris labrosa and two separate species of Megachile. All these bees have long tongues and are able to reach nectar at the bottom of the nectar chamber by legitimate visits. The inflorescences of S. tomentosa received more visits (0,62 visits/inflorescence/day) than the inflorescences of C. vitellina (0,37 visits/inflorescence/day). However, the fruit set of S. tomentosa (33%) is similar to that of C. vitellina (42%) in natural conditions, probably due to different pollinator efficiency. Having shorter tongues, Trigona and Augochlora bees have no access to the nectar chamber by means of legitimate visits. Hence, the dimensions of the nectar chamber of S. tomentosa and C. vitellina act as a selective barrier to short-tongued bees, thus guaranteeing more nectar to the long-tongued visitors. These legume pollinators are very common in the restinga forest, and they act as pollen vectors of other species in this ecosystem as well. The preservation of these legume plants is important to the diversity of bees and essential to the plant community. Resumo: O conhecimento das interações entre plantas e seus polinizadores tem-se destacado como ferramenta na biologia da conservação de ambientes degradados, como a Mata Atlântica e no estudo da evolução de características morfológicas que medeiam estas interações. Neste estudo são apresentadas informações sobre a biologia reprodutiva e as interações com os visitantes florais de Sophora tomentosa e Crotalaria vitellina (Fabaceae), espécies comuns em áreas de restinga na Mata Atlântica no Núcleo Picinguaba, Parque Estadual da Serra do Mar, Ubatuba -São Paulo. Estas espécies são sincronopátricas, possuem flores amarelas dispostas em racemos e oferecem néctar como principal recurso. Ambas as espécies são autocompatíveis, mas dependem de polinizadores para formação de frutos e sementes. Xylocopa brasilianorum e Megachile sp.1 foram os polinizadores de S. tomentosa, ao passo que C. vitellina, além destas espécies, também foi polinizada por Bombus morio, Centris labrosa e mais duas espécies de Megachile. Estas espécies de abelhas possuem comprimento da língua compatível com as dim...

ResumoOs visitantes florais são animais que buscam, nas flores, recursos para si ou para sua prole. Às vezes uma mesma planta pode receber um espectro grande de visitantes, como é o caso de espécies cujas flores oferecem muito néctar. Porém, nem todo visitante floral realiza a polinização. Para ser um polinizador efetivo é necessário cumprir alguns requisitos, como: contato com a antera e o estigma, frequência de visita suficiente, fidelidade floral e a realização de uma rota adequada de visitação. Em muitos trabalhos sobre a estrutura de comunidades e, principalmente, sobre a rede trófica (ex. animal-planta), os autores adotam o termo polinizador para todo e qualquer visitante floral, categorizando-os com o mesmo papel e função para a planta. Neste trabalho, relatamos casos de visitantes florais que são polinizadores legítimos e efetivos, dos quais a planta depende de seu serviço para produção de frutos e sementes, distinguindo-os daqueles visitantes que não efetuam a polinização, ou não se tem certeza que o façam. Assim, espera-se ilustrar as diferenças, dando à devida importância e o peso correto para os muitos visitantes. Utilizamos abelhas como modelo, mas a idéia pode ser extrapolada para qualquer outro grupo de polinizador. Palavras-chave: flores, rede de interação mutualista, reprodução vegetal, transferência de pólen, visita legítima. AbstractFlower visitors are animals that generally seek resources in flowers for themselves or their offspring. Sometimes the same plant may receive a broad spectrum of visitors, such as nectar species. However not all floral visitors complete pollination. To be an effective pollinator is necessary to fulfill some requirements, such as: contact with the anther and stigma, enough frequency of visits, fidelity to the plant, and the realization of a suitable route of visitation. In many works on the structure of communities and especially of food webs (animal-plant), the authors adopt the term pollinator for each and every flower visitor categorizing them with the same role and function for the plant. In this work we report cases of floral visitors who are legitimate and effective pollinators of which the plant depends on its service for the production of fruits and seeds, distinguishing them from those visitors who do not pollinate, or are not sure to do so. Thus, it is expected to illustrate the differences, giving due importance and the correct weight for the many visitors. We used bees as a model, but the idea can be extrapolated to any other pollinator group.

Invasive species can reach high abundances and dominate native environments. One of the most impressive examples of ecological invasions is the spread of the African sub-species of the honey bee throughout the Americas, starting from its introduction in a single locality in Brazil. The invasive honey bee is expected to more negatively impact bee community abundance and diversity than native dominant species, but this has not been tested previously. We developed a comprehensive and systematic bee sampling scheme, using a protocol deploying 11,520 pan traps across regions and crops for three years in Brazil. We found that invasive honey bees are now the single most dominant bee species. Such dominance has not only negative consequences for abundance and species richness of native bees but also for overall bee abundance (i.e., strong "numerical" effects of honey bees). Contrary to expectations, honey bees did not have stronger negative impacts than other native bees achieving similar levels of dominance (i.e., lack of negative "identity" effects of honey bees). These effects were remarkably consistent across crop species, seasons and years, and were independent from land-use effects. Dominance could be a proxy of bee community degradation and more generally of the severity of ecological invasions.

This study describes the floral phenology and morphology, reproductive biology and pollinators for eight legume tree species, Schizolobium parahyba, Senna macranthera, and Senna multijuga (Caesalpinioideae), as well as Andira fraxinifolia, Lonchocarpus cultratus, Pterocarpus violaceus, Swartzia oblata, and S. simplex (Papilionoideae), in the Atlantic Forest in Southeast Brazil. All the studied species showed an annual flowering pattern, and almost all are of the cornucopia-flowering type, with the only exception being Swartzia oblata, which was of the steady-state type. In general, the legume flowers studied are conspicuous, mostly medium-sized, and offer nectar and/or pollen as a resource. Self-incompatibility associated with the production of many flowers and consequent pollen discounting due to self-pollination may contribute to low fruit set of these species in natural conditions. Fifty bee species were recorded visiting the flowers, with medium to large-sized Apidae bees, such as Bombus morio, and species of Xylocopa, Centridini and Euglossina, which were among the most frequent visitors and major pollinators. These bees showed high floral constancy, thus they are significant to the reproductive success of these tree species. This study provides information regarding the interactions between bees and these eight legume species and evaluates the importance of pollinators for their sexual reproduction.

Inga species are characterised by generalist or mixed pollination system. However, this feature does not enhance reproductive rates in species with very low fruit set under natural conditions. Some ecological and genetic factors are associated with this feature, and to test the effect of massive visits on pollination success in Inga subnuda subsp. luschnathiana, we studied the efficacy of polyads deposited on stigmas of flowers isolated from visitors and polyads exposed to visitors. The proportion of polyads fixed in stigmas decreased after exposure to visitors (24 h) in comparison to stigmas isolated from visitors (hummingbirds, bees, wasps, hawkmoths and bats), and fruit set was very low. Furthermore, nectar production, sugar composition and other floral biology traits were evaluated. Increased nectar production, sugar availability and sucrose dominance during the night indicates adaptation to nocturnal visitors and supports their role as main pollinators; although the brush-flower morphology, time of anthesis, nectar dynamics and chemical composition also allow daytime visitors. Thus the species is an important resource for a diverse group of floral visitors. We conclude that excess visits (diurnal and nocturnal) are responsible for the decrease in fixed polyads in stigmas of I. subnuda subsp. luschnathiana flowers, thus contributing, with others factors, to its low fruit set. Therefore, the generalist pollination system does not result in reproductive advantages because the low fruit set in natural conditions could be the result of a negative effect of visitors/pollinators.

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