INSECT CONTROLLED POLLINATION IN JAPANESE PLUM (PRUNUS-SALICINA LINDL.)

Trials were performed in a commercial orchard of self-incompatible plu m, whose pollination and fruit yield often are a real problem in this early blooming crop. For this reason we introduced in the orchard hone y bees, mason bees, and bumble bees. The efficiency of pollinator inse cts was evaluated in the open field by counting-for 3 h a day in five sampling areas of the orchard-the number of visits to the flowers of t he main cultivar, No bumble bees were detected visiting the flowers of the main cultivar. The other two pollinators. showed a foraging activ ity which decreases by increasing the distance from their respective s tarting points: In each sampling area, the total number of visits was strongly related to fruit number and total yield. No significant diffe rences were detected regarding fruit quality. Fruit yield of the most visited areas was very close to that obtained after mechanical pollina tion by pollen spray. Pollination was also performed on caged trees, u sing the different insects separately in order to evaluate their respe ctive efficiency. (C) 1998 Elsevier Science B.V.