Variations in the weights of pollen loads collected by Apis mellifera L.

Abstract

Pollen traps were used to sample pollen loads collected by Apis mellifera through the day, their botanical origins were determined and variations in their weights were studied. Differences were observed in the mean load weights collected in the different periods of the day. The heaviest loads were recorded at midday or at the beginning of the afternoon. Considerable differences were found between the mean load weights from the different species, those of Fedia cornucopiae and Fragaria vesca being the heaviest ones. The different intensity with which the bees collected each pollen resource does not explain the differences in weight between the loads for the different species. The results also show that the pollen grain size and the presence or absence of nectar are not determining factors of the mean load weight for each species. Each species showed a different pattern of variation in load weights through the day. The predominating cases were those in which the heaviest loads were collected at midday or at the beginning of the afternoon. Nevertheless, there were cases where the heaviest loads were collected in the morning or at the end of the afternoon. The range of variation in mean load weight during the day was very different depending on the pollen source. The results show that the mean load weight of the each type varies through the day, and that it depends significantly on the rate of collection of the pollen resource in question in each time period: when the collection is more intense, the loads tend to be greater.