Cosecha polínica por Apis mellifera (Hymenoptera) en el bajo Delta del Paraná: comportamiento de las abejas y diversidad del polen

Resumen

Pollen gathering by Apis mellifera (Hymenoptera) in the lower Delta of the Paraná River: bee behavior and pollen diversity. A melissopalinologycal analysis of Apis mellifera corbicular pollen loads was made in order to determine pollen origin and main pollen sources throughout the bee foraging season in the Delta of the Paraná River. This analysis was based on 37 samples from the 1993-1994 beekeeping season. Bees gathered corbicular loads from about 20% of the available species throughout the season, but only 3% of these species were intensely used. The most abundant pollen grains belonged to Asteraceae, Leguminosae, Myrtaceae, Brassicaceae and Salicaceae. The pollen species varied throughout the sampling period. Nutritious quality was generally high. Anemophilous pollen types were harvested when the environmental offer dropped. Cultivated and exotic species heavily contributed at the end of winter and in spring, while native species were preferentially gathered in summer and autumn. The behavior of foraging bees was polylectic, with high pollen diversity in the corbicular loads and plasticity in use of local elements, and selective for the preferential use of lipidic -more energetic- pollen grains.