| In this study, five fields of Alfalfa Medicago sativa were selected from certain region in Babylon governorate during flowering period , May to October. ten species selected from pollinators diagnostic in previous study which belong to super family Apoidea,there are: Nomia sp2.(near to N. nortoni) , Nomia melanderi , Halictus ligatus , Lasioglossum pilosus , Nomioides vareigata , Homalictus sp.1(near to H. rowlandi) (Halictidae) , Megachile rotundata , Megachile sp.2(near to M.latimanus) , Megachile sp.4 (near to M. texana)(Megachilidae) , Apis mellifera (Apidae).The ten selected pollinators were compared according to the average of pollen load, the percentage of Alfalfa pollen grain in the pollen load. the results showed that six species pollinators within the ten selected species of Apoidea were significantly more active in the efficiency factors , these were Nomia sp2. , Nomia melanderi , (Halictidae) , Megachile rotundata , Megachile sp.2 , Megachile sp.4 (Megachilidae) , Apis mellifera (Apidae). The females of M.rotundata was significantly more efficient in pollen grain collection , the average number of pollen grain reached to (49750) followed by females of , Megachile sp.2 , Megachile sp.4 , Nomia melanderi (34300 , 32600, 31550) pollen grain respectively . While males collected good numbers of pollen grain, which seems they were importance in the pollination of Alfalfa flowers .The selected pollinators varied in average number of pollen grain in various months . However, it was found that the pollen load of each species was high during July and August compared with other month, the pollen load collected by of females M.rotundata was highest significantly compared with another species. On the other hand, the highest average percentage of Alfalfa pollen grains was reached to 91.5% by females of M.rotundata followed by Nomia melanderi reached to be 85.7% , while the lowest percentage was 62.6% by Nomia sp2.The average percentage of Alfalfa pollen grain within pollen load was different significantly in each month of the study period. However, it was found that the percentage of Alfalfa pollen grain was high during July and August compared with the other months . The highest percentage of Alfalfa pollen grain was reached to (100 %) in July by M.rotundata and Nomia melanderi and was reached to (100 , 94.1%) in August also by the two species respectively . thereupon, it seems clearly that these six species of Apoidea were appeared to be specialization for Alfalfa crop pollination. |