The java-producing shrub Coffea arabica is self-pollinating, so scientists thought that the presence of pollinating insects would have little or no effect on how the plant fared. But when David W. Roubik of the Smithsonian Tropical Research Institute studied 50 coffee plants from a Panamanian plantation, he found that those visited by insects bore fruit that was 7 percent heavier on average than that produced by plants protected from insect company. More specifically, plants visited solely by African honeybees showed a weight increase of 25 percent. Roubik notes that different pollinators affected crop yields to varying degrees but that "bees consistently controlled over 36 percent of the total production."
Roubik reports that coffee yields from Caribbean islands, where bee colonies are virtually nonexistent, are less than half of those from similar sites in Mexico and Central America, where bees are ubiquitous. Moreover, yields of coffee crops in Ivory Coast, Ghana, Kenya, Cameroon and Indonesia have decreased by 20 to 50 percent despite the fact that the areas set aside for coffee cultivation have grown up to fivefold over the past few decades. Traditional coffee plantations included a variety of plants grown above and below C. arabica, which provided diverse habitat for wildlife such as birds and bees. Most current commercial crops, in contrast, are grown on coffee-only fields. Such aggressive cultivation can harm pollinators by, among other things, eliminating nesting sites. Roubik suggests that "coffee plants would benefit from being grown in habitats that are suitable for sustaining valuable pollinators."