G. Ne'Eman et al., A new pollination probability index (PPI) for pollen load analysis as a measure for pollination effectiveness of bees, J APICULT R, 38(1-2), 1999, pp. 19-23
Conventional pollen load analyses have calculated the proportion of pure to
mixed pollen loads, or the average percentage of conspecific pollen on bee
s captured at their nests or hive. These indices can not distinguish 'flowe
r' constancy from 'pollen' constancy, and are poor estimates for the probab
ility of pollination. This study proposes a new index for pollen load analy
sis which reflects floral constancy at the pollinator population level and
therefore may be an estimation for pollination probability (PPI). This inde
x is the product of the mean proportion of conspecific pollen on bees captu
red on a certain forage flower species multiplied by the proportion of bees
carrying that conspecific pollen. The PPI can be used to estimate the prob
ability of pollination in natural plant populations as well as in crop plan
ts. This study calculated the PPI for bumble bees foraging on five keynote
species of a mediterranean phrygana: two polleniferous (Hypericum triquentr
ifolium and Myrtus communis) and three nectariferous (Cephalaria joppensis,
Echinops adenocaulos and Salvia fruticosa) plant species which are the mai
n food sources of Bombus terrestris under the local conditions.