Abstract

In the 1998/99 season, the pollinating activity of the bumblebees Bombus dahlbomi (Guérin) and Bombus ruderatus (F.) on red clover (Trifolium pratense L.) for seed production was studied in the localities of Gorbea and Nueva Imperial in the IX Region of La Araucania, Chile. During the 1999/2000 season, the distribution, relative abundance and size of the proboscis were recorded. Both species are widely distributed in the Region, with a relative abundance of 58.8% and 41.2%, respectively. A greater pollinating activity could be observed in the morning and evening intervals, with B. ruderatus being more active in visiting a greater number of flowers and spending more time than B. dahlbomi. A preference of this latter species was observed for higher native plants, while B. ruderatus preferred herbaceous and exotic plants. The mean size of the proboscis was 9.86 mm for B. dahlbomi and 9.77 mm for B. ruderatus, concluding that both bumblebees belong to the group of Bombus with a long proboscis, able to pollinate flowers with deep corollas such as red clover.