The value of bees to the coffee harvest.

The self-pollinating African shrub Coffea arabica, a pillar of tropical agriculture, was considered to gain nothing from insect pollinators. But I show here that naturalized, non-native honeybees can augment pollination and boost crop yields by over 50%. These findings, together with world coffee-harvest statistics and results from field studies of organically shade-grown coffee, indicate that coffee plants would benefit from being grown in habitats that are suitable for sustaining valuable pollinators.