Africanized bees rescue loner trees

Sure, Africanized bees spread like wildfire and attack in mobs. But they’re not all bad. In fact, for some trees, they’re saviors.

Certain lowland tropical trees that have survived deforestation and ended up alone in some pasture or other altered landscape have earned the nickname “the living dead,” says Christopher W. Dick of Smithsonian Tropical Research Institute at Naos, Panama. Since their native pollinators often disappeared with the rest of the ecosystem, these lone trees seemed fated to become the last of their lineage.

At least that’s what ecologists thought until Dick studied Brazil’s Dinizia excelsa. This pea relative, which can reach 60 meters in height, is typically distributed sparsely in forests.

Dick studied D. excelsa adults in a variety of landscapes. In intact forests, he found native bees pollinating the trees’ yellow flowers. In forest fragments, Africanized bees joined the natives on the job. The 10 loners he studied were visited only by Africanized bees.

Fortunately, these substitutes for native pollinators do a fine job, perhaps even a superior one, says Dick. The trees they visited, in pastures and in forest fragments, ripened three times as many seed pods as the trees worked only by native bees did. DNA analysis found that even isolated trees were spreading their pollen around just as much as trees serviced only by native pollinators were. As Dick puts it in the Nov. 22 Proceedings of the Royal Society of London B, the Africanized bee “has helped to bring D. excelsa back from the ranks of the living dead.”