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Africanized bees caused less damage to native bees

A 17-year study revealed also that "killers" may increase the availability of food plants for "victims"

Aggressive African bees were accidentally released in Brazil in 1957 and scientists feared that dangerous swarms of these would compete with native bees.

"Our long view of the invasion shows that bees maintain higher-order evolutionary relationships with plants despite ups and downs in bee species within families," said Roubik, researcher of the Smithsonian Tropical Research Institute.

Pollen from each plant species has a unique shape. Researchers compared pollen on bees in traps to pollen from flowers in the forest to determine which plants the bees were visiting.

Over the next 17 years, a severe drought and three hurricanes devastated native bees, but their populations rebounded each time. Africanized bees took over pollination of two plant families that had been important food sources for native bees: the cashew family and the spurge family. However, Pouteria, one of the plants native bees prefer, became more common. A few rare species of bees disappeared from traps later in the study.

Roubik cautions that native populations in less diverse areas might be less resilient to invasions. "Basically we're seeing 'scramble competition' as bees replace a lost source of pollen with pollen from a related plant species that has a similar flowering peak—in less-biodiverse, unprotected areas, bees would not have the same range of options to turn to."

by S. C.
05 october 2009, Technical Area > Science News