Search results for "pollina"

La pollinisation du cassis : État des lieux dans un contexte de changements anthropiques.

2019

Cultivated plants are part of their agroecosystem. Recent anthropic changes modified and decreased the wildcompartment of agroecosystems leading to a lowering of ecosystemic services such as pollination. Blackcurrant ispollinated at least partially by insects. In a study on 8 sites in Côte-d’Or, Burgundy, France we showed that pollinatordensity is lower than 0.5 pollinators per minute of observation in blackcurrant orchards. Blackcurrant are preferentiallyvisited by Bombus sp. and to a lesser extent by Andrena and Apis sp. Comparison of pollinator abundance between2018 data and data from ancient publications show that even if the floral abortion rate did not vary significantly, thenumber of…

Contribution des pollinisateurs dans la production de colza et de tournesol en zone atelier « Plaine et Val de Sèvre »

2018

Insect pollination is essential for over 70% of crops around the world. However, the contribution of pollinators to crop production and the insects involved in crop pollination have rarely been studied. Moreover, assessments of pollinator contributions have mostly been conducted on a small scale or under simplified conditions, which do not represent the real contributions at the field scale and do not take into account possible interactions between pollinators and farming practices. The aim of this study is to quantify directly under field conditions, the contribution of pollinators in two crops frequently cultivated in Europe: oilseed rape and sunflower. Estimations are realized both at th…

Should we manage weeds for bees ?

2014

National audience

From Shadow to Light. Inscriptions in Liminal Spaces of Roman Sacred Architecture (11th–12th Century)

2019

De la performance musicale dans la Guyane traditionnelle : expression cognitive singulière d?une musique-verbe

2021

Guianese culture and traditional music, here evoked, are various. It is more a transcultural process that, along centuries, gave an original result born in the Americas, in Guiana in this case. It is a form of refoundation, of recreation of cultures and new human beings generally called Creoles. The musical performance, that I study here, is the echo of social and cultural space of this reformulation of thought, life, and conception of the world. It is, as well, a mean of transposition and transformation of the values issued of diverse sources and categories. It is in no way a second-rate cultural practice, as it is the place where were born philosophies and actions for common life as well …

Breeding system and conservation strategy of the extremely endangered Cistus carthaginensis Pau (Cistaceae) of Spain

2001

Cistus carthaginensis is one of the most endangered plants in Europe: at present there exist only a few individuals in Murcia and one in Valencia (SE and E Spain). To design an adequate conservation strategy able to avoid the extinction of this species, various aspects of its reproductive biology were studied. The extreme rarity of C. carthaginensis is not related to problems of development and/or fertility of pollen or ovules produced by the few existing specimens. Meiosis in the pollen mother cells is always regular and chromosome segregation is completely equilibrated in the male gametes. Pollen and ovule production is high and similar to that reported for other related species of Cistus…

The floral nectaries in theLimnanthaceae

1992

Floral nectaries in theLimnanthaceae are established as exoscopic basal bulges of the episepalous stamens. Their nectariferous tissues include the epidermis and hypodermal parenchyma and inLimnanthes are vascularized by phloematic branches of the staminal bundles. Secretion occurs mainly through anomocytic stomata but, in addition, probably through the outer cuticularized thin walls of the epidermal cells. The flower structure is comparatively simple. The nectar is often slightly concealed. A wide range of pollinators can be expected, but bees are observed to be the dominant ones. The systematic position of the family is still obscure. Taxonomic placement near to any other geranialian famil…

Pollination of four sympatric species ofAngelonia (Scrophulariaceae) by oil-collecting bees in NE. Brazil

1991

The manner whereby the oil-producing bisaccate flowers ofAngelonia (Scrophulariaceae) are pollinated by female oil-collecting bees is reported for the first time. Observations were made in the Caatinga formation of Pernambuco, NE. Brazil, on four synchronopatric species. These differ in sizes and structural details of the corolla, level of flower exposition, and habitat preferences. All legitimate visitors wereCentris spp. (Anthophoridae):Angelonia hirta was mainly pollinated byC. fuscata andA. pubescens byC. hyptidis; A. bisaccata andA. hookeriana shared an unidentified species. Several exomalopsine, tetrapediine and meliponid bees exploit the flowers less descriminately for oil or pollen,…

The perfume flowers ofCyphomandra (Solanaceae): Pollination by euglossine bees, bellows mechanism, osmophores, and volatiles

1993

The perfume syndrome and pollination by fragrance-collecting euglossine bees in the neotropic solanaceous genusCyphomandra was confirmed by field observations. In SE Brazil,C. sciadostylis was visited byEufriesea violaceae, andC. diploconos byEuglossa mandibularis; C. hartwegii was pollinated byEulaema meriana in Costa Rica. The primary attractant, fragrant droplets that ooze from the dorsally bulged connectives, is mopped up by the males with the forebasitarsi. Thereby, the poricidal thecae are inadvertently pushed causing the dry pollen to dust the bee's sternum. The number and direction of the pollen jets are related to pollinator size and stigma structure. The flowers are homogamous, se…

The pollination syndrome ofDeplanchea tetraphylla (Bignoniaceae)

1986

The reproductive structures ofDeplanchea tetraphylla (Bignoniaceae) exhibit a significant number of unusual features: inflorescence with an apical “platform”; flowers yellow, short-tubed, strongly zygomorphic; mouth closed through lateral compression; stamens and style long-exserted, erect or slightly reclined; nectar dark brown, exposed in the spoon-shaped lowermost corolla lobe and apparently acting also as a visual cue. These features suggest a highly elaborate syndrome for bird pollination: the birds (probably lorikeets) perch on the inflorescence platform and bend downwards to take up the exposed nectar, thus touching the exserted anthers and stigmas with the throat or breast. The like…