Impact of honeybee and bumblebee pollination on alfalfa seed yield

Abstract

This study was conducted to determine the effects of honeybee (Apis mellifera L.) and bumblebee (Bombus terrestris L . ) on alfalfa (Medicago sativa L.) seed production in the west Mediterranean region of Turkey, between 2001 and 2003. The experimental plots (4×3 m) were arranged in a randomized complete block design with three replications for spring and autumn seasons. Four pollination treatments (caged with bumblebee (BP), caged with honeybee (HP), open-pollinated (OP) and pollinator excluded (EP)) were applied. The effects of honeybee and bumblebee on alfalfa seed yield, number of pods per raceme, number of seeds per pod, and podding rate were investigated. The results of seed yield indicate that interaction between treatment groups and seasons was significant (p<0.01). The highest seed yield in alfalfa was found in OP (66.19kg/ha) in the spring followed by BP (56.48kg/ha), HP (49.20kg/ha) and EP (2.44kg/ha). With regarding to the autumn season, the highest seed yield was found in BP (26.17kg/ha) treatment followed by HP (22.89kg/ha), OP (18.12kg/ha) and EP (1.96kg/ha). The results of this research show that B. terrestris can be recommended as an alternative pollinator to honeybee for alfalfa seed production.