EFFECTS OF SEED ONION POLLINATION BY RED MASON BEE FEMALES Osmia rufa L. (Apoidea; Megachilidae) WITH DIFFERENT BODY WEIGHTS Karol G iejdasz, Z dzis³aw W ilkaniec, Katarzyna P iech

Summary The study was aimed at determining the impact of body weight of red mason bee Osmia rufa L. females on the pollination efficiency of seed onion Allium cepa L. and the quality of seed yield. The results obtained demonstrated that the body weight of Osmia rufa females used for onion pollination had no significant effect on the pollination efficiency nor the quantity or quality of seeds. It can be observed that the percentage of fruits set compared to the number of flowers in an inflorescence tended to decrease with smaller body weights of the bee females from particular experimental groups. In addition, the other experimental results (total seed yield, germination energy and capacity) confirmed that weaker parameters of pollination efficiency and seed quality were achieved in the case of onion pollination by females with the lowest body weight.