POLLENS COLLECTED BY WILD AND MANAGED POPULATIONS OF THE POTENTIAL ORCHARD POLLINATOR OSMIA-CORNUTA (LATR) (HYM, MEGACHILIDAE)

Pollen samples of provisions of the potential orchard pollinator Osmia cornuta were analyzed. Bee populations studied (from NE Spain) were o f 4 different origins: A. wild populations of almond-growing areas; B. wild populations of non-almond-growing areas; C. managed populations released in almond (Prunus dulcis) orchards; D. managed populations re leased in apple (Pyrus malus) orchards. Although pollen grains of 19 p lant families were identified in the samples, Prunus pollen was the do minant pollen type in all wild populations (A populations: 77-99 %; B populations: 55-85 %). Pollen of other Rosaceae was very scarce (A pop ulations: 0.03-12.3 %; B populations: 1-5.5 %). Prunus pollen was also the dominant pollen type in samples from C populations (78-99 %), and pollen of other Rosaceae was again very scarce (0-5 %). When bees wer e released in apple orchards (D populations), they overwhelmingly coll ected Pyrus pollen (92-94 %), and hardly any Prunus pollen was found i n the samples (0-0.01 %). These results are positive from the point of view of the potential use of 0. cornuta as a pollinator of orchard cr ops, since they indicate that the species preferentially collects Prun us pollen but, will switch to Pyrus pollen when this is more readily a vailable.