Evaluation of Bombus dahlbomii (Guér.) as a pollinating agent for tomato flowers under greenhouse conditions

Patricia Estay1, Adrian Wagner1 y Moisés Escaff1

The native bumblebee Bombus dahlbomii (Guér.) was assessed as a pollinating agent of cultivated tomatoes (Lycopersicon esculentum (Mill)) during the summer of 1998 in the Instituto de Investigaciones Agropecuarias (INIA), Centro Regional de Investigación La Platina, Santiago, Chile (33º 34’ S lat, 70º 38’ W long). The bees were obtained from wild hives and moved to artificial hives. They were released into a 24 m2 greenhouse containing tomato plants. A similar greenhouse without bumblebees was maintained as a control. The result showed that 80% of the tomato flowers were visited by the bees, measured by necrotic marks left in the stamen tube of the flower. On the other hand, it was possible to identify tomato pollen on the bee's legs and in the honeycomb of the beehive, so that the foraging action would favor pollen loosening of the flower anthers. A significant increase in the number of seeds was found on tomatoes with bee contact compared with the control. It was concluded that this species could act as a pollinating agent for tomatoes under greenhouse conditions. Average fruit set, weight and size were not affected by Bombus dahlbomii. It is necessary to evaluate this insect on winter and spring growing tomatoes.

Keywords: pollination, bumblebee, native insects, fruit characteristics.
1 Instituto de Investigaciones Agropecuarias, Centro Regional de Investigación La Platina, Casilla 439 Correo 3, Santiago, Chile. E-mail: pestay@inia.cl ; awagner@inia.cl.