Assessing the pollination requirements of a perennial crop

Approximately two thirds of crop plants require or benefit from insect pollination to produce economically viable fruit.  As honey bees continue to decline due to Colony Collapse Disorder and native bee populations are threatened by loss of habitat and resources, commercial crop yields face possible declines due to insufficient pollination.  Crops, however, vary in the degree to which they depend on pollinators.  Cranberry (Vaccinium macrocarpon), a perennial fruit crop native to North America, is generally considered to be greatly dependent on insect pollinators.  The purpose of this study was to assess to what extent biotic (i.e. bees) and abiotic (i.e. wind and agitation) factors effect cranberry pollination and therefore yield.  To address this objective we built cages to test the following treatments: (1) insects and wind, (2) just wind, (3) no insects or wind, and (4) no insects or wind but with manual agitation of the plants.  Cages were established before cranberry bloom began and removed once the plants stopped flowering.  Fruit was harvested at maturity and counted and weighed.  We found that plants open to all modes of pollination (i.e. insects and wind) produced the most number of berries.  We also found, however, that plants in cages that excluded insects but allowed wind produced a significant number of berries as compared to plants that received no pollination.  These results suggest that some crops that were previously believed to be greatly dependent on insect pollinators may be able to produce significant crops in the absence of insect pollinators.