Acceptance of artificial nesting sites by pollinating mason bees in commercial fruit plantations (Hymenoptera, Megachilidae: mixed Osmia cornuta and O. rufa population)

The native early spring mason bee species (Osmia cornuta and also O. rufa) have been known as effective pollinating agent of fruit trees in Europe (Bosch 1994a, Bosch & Kemp 2002, Krunic et al. 1995, Maccagnani et al. 2003, Pinzauti 1991, Vincens & Bosch 2000a). For this reason efforts were made to use artificially reared stocks for controlled fruit tree pollination (Bosch 1994c, 1995, Bosch & Blas 1994a, b, Krunic et al. 1995, Vincens & Bosch 2000b, c). On the other hand, in site propagation of native populations has also be found to be a proper (and much cheaper) method to increase pollinating wild bee density around fruit tree plantations (Benedek 2008). Exploiting this finding, we used simple bee shelters to increase natural pollinating wild bee population in some commercial fruit tree plantations and found that the bee shelters were accepted in different rates at different localities in orchards planted with different fruit tree species. These experiences may be important and useful to fruit growers.