Vacant rooms? The secondary use of stem-galls by ants in Eremanthus erythropappus (Asteraceae)

Galls are atypical proliferations of plant tissue induced by highly specialized herbivores, such as some insect groups. Although gall inducers create these structures for their own purpose (food, habitat, protection against natural enemies, and harsh weather), many other organisms can use galls as secondary inhabitants. The creation of new and better habitats with ameliorated micro-environmental conditions allows for the use of many other organisms, and as such, some galling insects are considered "micro" ecosystem engineers. This study characterized the occurrence of ants in microhabitats created by a gall-inducing cecidomyiidae associated with Eremanthus erythropappus (DC.) Mac. Leish (Asteraceae). It was 153 individuals of ants belonging to three species in 19 galls (9.5%) from the 200 galls sampled. The most common ant species found was Myrmelachista gallicola Mayr (Formicinae), including a single queen and larvae individuals. Galls occupied by these ants were 11.5% larger compared to unoccupied galls (gall diameter: occupied galls - 10.00 ± 2.09 mm; unoccupied galls - 8.97 ± 1.90 mm). Abandoned galls might promote the diversity of other organisms, especially for opportunistic dwellers such as ants

Floral resource availability and its use by hummingbirds in an area of cerrado of Uberlândia, MG

Although hummingbirds are considered an important group of pollinators, few studies about their ecology are available for some ecosystems. The Cerrado biome harbors one of the world richest vascular flora, but at a given community, the proportion of hummingbird pollinated flower is relatively low. Maybe driven by this trend, hummingbird visits are frequently recorded in non-ornithophilous flowers of Cerrado and these opportunistic visits may be crucial for their maintenance. In this sense our study had two aims: 1) to evaluate the floral resource availability for hummingbirds in a typical cerrado area and 2) to estimate the effect of hummingbird visits in the reproduction of a non-ornithophilous plant. In the first part of the study we characterized the assemblage of plants visited by the hummingbirds, the temporal and spatial dynamics of nectar (energy) availability, and factors affecting the frequency of hummingbird visits to the plants. Floral resource availability varied considerably during the year, in synchrony with the flowering of the most abundant species and without clear association with the seasonality typical of the Cerrado. The amount of nectar available per plant individual and the amount of nectar available in the entire area were the factors affecting the frequency of the hummingbird visits. In most of the nonornithophilous plants hummingbirds seemed to act as nectar thieves, since there was no morphological match between pollinator and flower. Nevertheless, in larger flowers and especially in brush flowers the hummingbirds may act as complementary pollinators. In the second part of the study, the effect of hummingbird visits to a non-ornithophilous plant (Styrax ferrugineus) was investigated. In this particular plant, hummingbird seemingly did not contribute directly in the pollination, since contact with the stigma rarely occurred, even though anthers were contacted frequently. Indirect effect of hummingbirds in the plant reproduction seemed to be minimal, since their exclusion from flowers did not affect fruit-set. The inability of hummingbirds in depleting all nectar produced in this mass-flowering plant and the existence of other resource (pollen) for the primary pollinator (large bees) are pointed as possible reasons for the absence of perceptible hindrance of hummingbirds in the plant reproduction. Even though the effect of hummingbird visits for non-ornithophilous plants were not clearly defined, for the bird perspective this opportunistic use of flowers is certainly important, especially in the Cerrado where hummingbird plant diversity is relatively low.Conselho Nacional de Desenvolvimento Científico e TecnológicoMestre em Ecologia e Conservação de Recursos NaturaisApesar de os beija-flores serem apontados como um importante grupo de polinizadores, poucos estudos sobre a sua ecologia estão disponíveis para alguns ecossistemas. O bioma Cerrado é um ecossistema que apresenta uma das mais ricas floras vasculares do mundo, mas numa dada comunidade desse bioma, a proporção de espécies ornitófilas parece ser relativamente baixa. Talvez forçadas por esta condição, visitas oportunistas de beija-flores a flores com outras síndromes florais no Cerrado parecem ser freqüentes. Nesse sentido este estudo teve dois objetivos: 1) avaliar a disponibilidade de recursos florais utilizadas pelos beija-flores numa comunidade de cerrado sentido restrito e 2) avaliar possíveis efeitos que as visitas de beija-flores tem na reprodução de uma planta não ornitófila. Na primeira parte do estudo, foi caracterizada a assembléia de plantas utilizadas pelos beija-flores, a dinâmica temporal e espacial da oferta de néctar (energia), bem como o uso e os fatores que afetam a utilização das plantas pelos beija-flores. Os resultados mostram que a disponibilidade de recursos florais variou de maneira considerável durante o ano, em sincronia com a floração das espécies mais abundantes, e sem clara associação com a sazonalidade típica do Cerrado. A quantidade de recursos oferecida pela planta e a disponibilidade de recursos para a área como um todo parecem explicar a freqüência com que determinada espécie de planta recebe visitas de beija-flores. Amazilia fimbriata e Eupetomena macroura foram as espécies mais freqüentes entre os beija-flores. Na maioria dos casos, os beija-flores parecem agir como ladrões de néctar quando em associação com as plantas não ornitófilas, já que não há um ajuste morfológico entre a flor e o polinizador. No entanto, em flores maiores e especialmente em flores do tipo pincel os beija-flores poderiam agir como polinizadores complementares. Na segunda parte do estudo, o efeito da visita de beija-flores numa planta não ornitófila (Styrax ferrugineus) foi investigado. Nessa planta em particular, os beija-flores parecem não contribuir de maneira direta para a reprodução da planta, já que apesar do contato com as anteras ocorrer frequentemente, as aves raramente tocam o estigma. Mesmo de maneira indireta, o efeito que os beijaflores têm na reprodução da planta parece ser pequeno, já que a sua exclusão não alterou as taxas de formação de frutos. A inabilidade dos beija-flores em exaurir todo o néctar presente na planta e a existência de outro recurso (grãos de pólen) para os principais polinizadores, abelhas, são apontados como fatores que minimizam o efeito da pilhagem de néctar. Mesmo que para as plantas o efeito da visita dos beija-flores não seja claro, sem dúvida o uso mais oportunista de recursos florais deve ser importante no ponto de visita dos beija-flores, especialmente no Cerrado onde a diversidade de flores ornitófilas é relativamente baixa

Pollination and breeding system of Canna paniculata(Cannaceae) in a montane Atlantic Rainforest: asymmetric dependence on a hermit hummingbird

We studied the pollination biology of Canna paniculata (Cannaceae), a plant species common in the Atlantic Rainforest of southeastern Brazil. The species presents specialized ornithophilous flowers, which in our study area are solely pollinated by the hermit hummingbird Phaethornis eurynome. Although C. paniculata is capable of bearing fruit after self-pollination, it requires pollinators for reproduction. We discuss the importance of hermit hummingbirds for the reproduction of specialized ornithophilous plants such as C. paniculata, including their asymmetric dependence on hermit hummingbirds - core pollinators in Neotropical forest ecosystems

When hummingbirds are the thieves: visitation effect on the reproduction of Neotropical snowbell Styrax ferrugineus Nees & Mart (Styracaceae)

The spectrum of floral visitors associated with a particular plant is frequently larger than predicted by the traditional concept of floral syndromes and the role that unpredicted visitors play in plant reproduction deserves attention. Hummingbirds are frequently recorded visiting flowers with distinct floral syndromes, especially in some hummingbird flower poor ecosystem such as the Cerrado. In this study we investigated the effect of frequent hummingbird visits on the reproduction of melittophilous Styrax ferrugineus. The flowers were visited by many different insect groups and visits by hummingbirds were frequent, especially early in the morning when nectar availability was higher. Nectar parameters varied considerably during the flower life span, and was probably affected by the temperature variation during the day. Hummingbird exclusion experiments showed no effect in the fruit-set of the plant. The inability of hummingbirds to deplete all of the nectar produced in this mass-flowering plant, and the existence of another resource (pollen) for the primary pollinator (large bees), are possible reasons why there was no perceptible hindrance of plant reproduction by the hummingbirds. Although no effect in the fruit-set was observed, the use of non-ornithophilous flowers must be important for hummingbirds, which are specialized nectar consumers

Parasites in the neighbourhood: Interactions of the mistletoe Phoradendron affine (Viscaceae) with its dispersers and hosts in urban areas of Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Mistletoes constitute an important food resource for animals in many ecosystems. However, these plants are considered pests in urban areas because of deleterious effects they have on the host trees. Studies in urban areas were mostly focused on listing host species or procedures to control the "pest". In this sense, broader studies including several aspects of mistletoes ecology in urban ecosystems are still missing. We studied the interaction of the mistletoe, Phoradendron affine, with its dispersers and hosts in two urban sites in Uberlandia, Brazil. Phoradendron affine fruits were consumed almost exclusively by Euphonia chlorotica, which was crucial for seed germination. Parasitism was recorded in five hosts, two native (Handroanthus chrysotrichus and Tabebuia roseoalba) and three exotic species (Spathodea campanulata, Ligustrum lucidum and Melia azedarach). Mistletoes were found parasitizing larger host trees, a trend commonly reported for mistletoe-host interaction. Mistletoe seed germination was not affected by the trees species, whether host or non-host, but the radicle of germinated seeds could not penetrate the bark and seedlings invariably died in non-host species. We found a high prevalence of parasitism in our study, in comparison to what previous studies reported for natural areas. The spatial distribution of the hosts and high light incidence on isolated host trees may lead to this high prevalence in urban areas. Rather than eradicated, mistletoes in urban areas should be ecologically managed and their importance for bird species conservation must be considered. More studies to determine which bird species are favoured by mistletoe presence in urban areas will be essential for, this purpose. (C) 2012 Elsevier GmbH. All rights reserved.20710768773Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPEMIGCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Trait patterns across space and time suggest an interplay of facilitation and competition acting on Neotropical hummingbird-pollinated plant communities

Pollinators may influence plant community assembly through biotic filtering and/or plant-plant competition and facilitation. The relative importance of each process, however, vary according to the scale and how strongly plants share their pollinators, and possibly in relation to the pollinator groups considered. We here investigated the assembly of three Atlantic forest hummingbird-pollinated plant communities across space (among all species in the communities) and time, i.e. yearly flowering phenology (between pairs of co-flowering species), based on the pairwise distances of multiple floral traits (corolla length, anther and stigma height, colour and nectar). Because tropical hummingbird-pollinated plants are often subdivided in two pollination niches (hermits versus non-hermits), we also analyzed these groups separately. We found that trait structure across space was clustered for some floral traits, suggesting biotic filtering and facilitation. All floral traits had weak phylogenetic signal, indicating that closely related species were not more similar than distantly related species. Moreover, floral traits were randomly structured along the phenology when analyzing all plants together. On the other hand, we found similar corolla length but divergent anther height in co-flowering pairs within the same pollination niche. Thus, plants may benefit from flowering together and avoid competition through fine adjustments in reproductive traits. The results also suggest that clear signals of competition and facilitation among plants are only apparent when species strongly share their pollinators and depending on the traits that are considered. Our study illustrates a complex interplay of biotic filtering, facilitation and competition as processes structuring guilds of plants sharing the same functional group of pollinators1271116901700CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP830514/1999-6; 303084/2011-1sem informação2013/15129-9; 2015/21457-