Nectar Secretion Pattern and Removal Effects in Six Argentinean Pitcairnioideae (Bromeliaceae)

Galetto, Leonardo; Bernardello, Luis M.

doi:10.1111/j.1438-8677.1992.tb00301.x

Cited by 47 publications

(55 citation statements)

References 35 publications

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“…Essa medida permitiu calcular a produção média de néctar e, consequentemente, determinar o padrão de secreção de néctar. Em outro grupo de flores foram feitas medidas repetidas em cada flor com intervalos de duas horas, mantendo as flores ensacadas entre as medições, de acordo com Galetto & Bernardello (1992). Esse conjunto de flores foi dividido em cinco grupos com seis flores cada; as medições do néctar do primeiro grupo iniciaram às 7h00, do segundo grupo às 9h00 e assim sucessivamente até o último grupo, às 15h00.…”

Section: Methodsunclassified

Atributos florais em um sistema de polinização especializado: Calathea cylindrica (Roscoe) K. Schum. (Marantaceae) e abelhas Euglossini

Barreto¹,

Freitas²

2007

Rev. bras. Bot.

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-(Floral traits in a specialized pollination system: Calathea cylindrica (Roscoe) K. Schum. (Marantaceae) and Euglossini bees). Pollination specialization is promoted by floral features that favor pollinator fidelity and hinder the access to resources by other visitors. We investigated the pollination mechanism of one understory herb in southeastern Brazil. Calathea cylindrica flowers year-round and its flowers are peculiar because of the fusion and modification of some elements, asymmetry, secondary pollen presentation, hidden nectar, and a long and narrow tube, which is closed before pollinator visit. Pollination occurs by means of an explosive mechanism, and once it is triggered, the floral parts do not return to their initial position. Thus, there is only a single possibility for pollen transference. Pollinators are female Euglossini bees and all flowers have already been visited by mid-morning. Specific movements with enough force are necessary for the visitors to access the nectar. Bagged flowers secreted around 13 µL of nectar with 32% of sugar concentration. Nectar secretion continues after removals, but in small volumes. Continual flowering, high production of nectar and secretion after pollination may promote pollinator fidelity. The complex floral structure, the secretion in which the flower base (nectar chamber) is dipped, and the narrow tube with inner hairs make the access to nectar difficult and may work as barriers for other visitors. Altogether, these factors seem to regulate the highly specialized pollination system of Calathea cylindrica.Key words -bee, Euglossini, floral specialization, nectar, pollination RESUMO -(Atributos florais em um sistema de polinização especializado: Calathea cylindrica (Roscoe) K. Schum. (Marantaceae) e abelhas Euglossini). Sistemas de polinização especializados estão ligados a características que incentivam as visitas por polinizadores e desestimulam visitas por outros animais. O mecanismo de polinização de uma espécie de Marantaceae foi estudado com ênfase nessa questão. Calathea cylindrica é uma erva com flores disponíveis o ano todo. As flores são peculiares pela fusão e modificação dos elementos, assimetria, apresentação secundária de pólen, néctar pouco acessível e tubo longo, estreito e fechado até a visita do polinizador. A polinização consiste em um mecanismo explosivo, sendo que uma vez disparado, as estruturas florais não retornam à posição inicial. Assim, há uma única possibilidade para transferência de pólen. Os polinizadores são fêmeas de abelhas Euglossini (Apidae) e no meio da manhã todas as flores já haviam sido visitadas. O acesso ao néctar em flores intactas requer a realização de movimentos específicos e com força apropriada, o que exclui outros insetos. A quantidade de néctar produzido em flores ensacadas foi em torno de 13 µL com 32% de concentração de açúcares. O néctar continua sendo secretado em quantidades pequenas depois do disparo do mecanismo. A floração contínua, a quantidade alta de néctar produzido e a continuidade de secreçã...

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Section: Methodsunclassified

Atributos florais em um sistema de polinização especializado: Calathea cylindrica (Roscoe) K. Schum. (Marantaceae) e abelhas Euglossini

Barreto¹,

Freitas²

2007

Rev. bras. Bot.

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“…Unfortunately, most studies that evaluate the effects of nectar thieves and robbers on nectar availability have measured differences in volume of nectar (McDade & Kinsman 1980, Morris 1996, Roubik 1982, Roubik et al 1985, and the same approach is provided by studies investigating the role of flower mites as nectar thieves (Colwell 1995, Cruz et al 2007, Lara & Ornelas 2001, 2002b. The problem in measuring only nectar volume and sugar concentration is that these variables vary greatly with period of the day (as in the present study), with nectar removal and flower age (Galetto & Bernadello 1992), but also with abiotic factors such as temperature and atmospheric relative humidity (Galetto & Bernadello 2005). Thus, for a better assessment of nectar production costs and energetic content, it is necessary to transform samples with volume and concentration in sugar biomass (Galetto & Bernadello 2005).…”

Section: Discussionmentioning

confidence: 86%

“…Bromeliad nectar is mainly composed of water and sugars, with the proportions of fructose, glucose and sucrose varying among species within three subfamilies, producing insignificant quantities of amino acids and no lipids or proteins (Bernadello et al 1991). Galetto & Bernadello (1992) observed that nectar removal increased secretion but decreased sugar concentration in some bromeliad species. However, these effects did not alter the total amount of sugar secreted, except for Puya spathacea, in which nectar removal decreased both nectar volume and sugar amount.…”

Section: Introductionmentioning

confidence: 99%

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Flower mites decrease nectar availability in the rain-forest bromeliadNeoregelia johannis

2010

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Nectarivorous flower mites can reduce the volume of nectar available to pollinators. The effects of the flower mite Proctolaelaps sp. on nectar availability in flowers of a melittophilous bromeliad Neoregelia johannis (Bromeliaceae) was evaluated in a coastal rain forest in south-eastern Brazil. In a randomized block experiment utilizing 18 flower pairs, one per bromeliad ramet, pollinators (Bombus morio) and mites were excluded, and then nectar volume, sugar concentration and sugar mass were quantified over the anthesis period. Mites significantly reduced nectar volume early in the morning (6h00-8h00), but not later (10h00-12h00). Mites decreased total volume of nectar available up to 22%. Sugar concentration in nectar was higher earlier in the morning, and decreased between 10h00-12h00. The pronounced consumption of nectar by mites during the period of higher sugar concentration reduced the total amount of sugar available to pollinators by 31%. This is the first study showing that flower mites decrease nectar rewards in a melittophilous plant. Because nectar volume by itself incompletely describes nectar production rates and the effects of nectar removal by flower mites on the availability of sugar, our study highlights the inclusion of sugar content in future studies assessing the effects of thieves on nectar production rates.

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“…A reabsorção do néctar permite que a planta economize recursos importantes que não foram utilizados pelos polinizadores (Burquez & Corbet 1991;Luyt & Johnson 2002). Outra possibilidade é que as flores desta espécie sejam estimuladas a produzir mais néctar conforme este recurso seja retirado pelos visitantes florais (Gill 1988;Galetto & Bernardello 1992). Neste caso, a produção de néctar pode ter sido subestimada, já que este foi retirado a cada duas horas e as flores foram visitadas em todos os horários de observação, ou seja, pelo menos uma vez por hora.…”

Section: Resultsunclassified

Fenologia, morfologia floral e visitantes de Psychotria brachypoda (Müll. Arg.) Britton (Rubiaceae) em uma área de Floresta Atlântica, Sudeste do Brasil

2008

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Corolla length and diameter of thrum flowers were larger than those of pin flowers. Although stigma length corresponded approximately to stamen length in each morph, exact reciprocal hercogamy did not occur. The nectar was more concentrated at 06:30h (33%) and more diluted at 14:30h (26%). Flowers in which nectar was collected throughout the day had about three times more nectar than flowers in which nectar was collected once at the end of the day. There were 24 plants with thrum flowers and 25 plants with pin flowers, indicating an isopletic population. The main floral visitors were females and males of the hummingbird Thalurania glaucopis, bees of the tribe Trigonini and of the genus Euglossa, three Lepidoptera species, one Diptera species and one Coleoptera. Fruit was produced in 13.7% of the total number of marked flowers, with similar production in both morphs. Thalurania glaucopis is probably the most important pollinator of P. brachypoda, because it often visits many flowers from different individuals of P. brachypoda, probably transferring pollen among them.

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Nectar Secretion Pattern and Removal Effects in Six Argentinean Pitcairnioideae (Bromeliaceae)

Cited by 47 publications

References 35 publications

Atributos florais em um sistema de polinização especializado: Calathea cylindrica (Roscoe) K. Schum. (Marantaceae) e abelhas Euglossini

Atributos florais em um sistema de polinização especializado: Calathea cylindrica (Roscoe) K. Schum. (Marantaceae) e abelhas Euglossini

Flower mites decrease nectar availability in the rain-forest bromeliadNeoregelia johannis

Fenologia, morfologia floral e visitantes de Psychotria brachypoda (Müll. Arg.) Britton (Rubiaceae) em uma área de Floresta Atlântica, Sudeste do Brasil

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