Africanized bees make better shoppers.

Part of the secret to world domination--in the honeybee realm, at least--may involve collecting more pollen than nectar.

Jennifer H. Fewell and Jon F. Harrison of Arizona State University in Tempe were studying local wild honeybees when Africanized bees buzzed in during 1005. Chronicling the rapid takeover, Fewell and Harrison noted that Africanized bees swarmed to start new colonies two or three times faster than the resident European bees did.

To figure out how the newcomers reproduce so quickly, the researchers set up glass-sided observation hives for both Africanized and European bees. Each started with 1,000 marked bees, and researchers tracked activity bee by bee.

Africanized bees were more likely to collect pollen--a High-power baby food--while European bees were more likely to bring home nectar--a good ration for winter. In a climate like Arizona's, the pollen-skewed colonies did not suffer in cold weather.

In the Africanized colonies, and much less so in the European ones, worker metabolisms revved up when bees got old enough to forage. Thus they worked harder than their European counterparts. The Africanized bee baby boom, Fewell and Harrison propose, comes in part from extra effort and extra pollen.