Resumen

MUSICANTE, Mariana L  y  GALETTO, Leonardo. Nectar characteristics of Cologania broussonetii (Balb.) DC. (Fabaceae) and its relationship with flower visitors. Ecol. austral [online]. 2008, vol.18, n.2, pp.195-204. ISSN 1667-782X.

Relationships between flowering plants and their pollinators are usually affected by the amount and quality of reward, mainly pollen or nectar, offered to pollinators. Here we analyzed nectar sugar composition, nectar secretion pattern, the effects of removal of nectar on the secretion pattern, and the relationships between these variables and the frequency of visits of the pollinators in Cologania broussonetii (Fabaceae). Nectar sugar composition showed sucrose 62%, fructose 24% and glucose 14%. Nectar secretion resulted continuous through the first day after flower opening. When flower nectar was not removed, during the second day of flower lifetime the sugar content declined due to nectar reabsorption. Nectar removal did not affect the total amount of sugar produced by the flowers. Flowers were visited in low frequencies just by two bumblebees: Bombus opifex and Bombus bellicosus (Hymenoptera: Apidae). Some of the nectar secretion traits can be related with a low frequency of pollinator visits. Thus, considering the nectar secretion pattern in these species seem to be in accordance with variables and unpredictable visit rates.

Palabras clave : Faboideae; Flower visitors; Bombus sp.; Sugar nectar composition; Nectar secretion pattern.

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