Aggressive African bees were accidentally released in Brazil in 1957. As “killer bees” spread northward, David Roubik, staff scientist at the Smithsonian Tropical Research Institute, began a 17-year study that revealed that Africanized bees caused less damage to native bees than changes in the weather and may have increased the availability of their food plants.

Let me add a little context before you go back to the press release.

Apis mellifera, is most well known ‘honey bee,’ and is one of the only stinging honey bees (famous for being suicidal stingers … worker bees will swarm an invader and thousands of bees may give their lives to protect the hive). Most other honey bees neither sting nor make huge hives (most of the stingy things are wasps or some other kind of bee that is not exploited for honey because they make none or only a dab), but they do tend to make some kind of storage of some kind of honey, live colonially, and serve as pollen vectors.

In other words, honey bees as a group share the characteristic of being relatively numerous and storing food that they can protect aggressively, and of being generalized pollen vectors. So, one question that might arise is: How interchangeable might they be in a given local ecological setting? This is important when considering the effects of species invasion.

(By the way, next time you are at the heath food store or the healthy-seeming fast food emporium, and they ask you if you want “bee pollen” in your smoothie, don’t forget to ask them exactly what “bee pollen” is ….)

Anyway, Apis mellifera is a wild insect of Africa and Asia, tropical and semi tropical, living in a wide range of ecologies, as long as there is nectar. This is the species that was domesticated to create the honey bee of the bee farm, the one that produces the honey in the white boxes set off to the side of the orchard, and so on.

The so called “African Killer Bees” are nothing other than the wild version of the honey bee. This is a little hard for many people to get their heads around because there are not a lot of well known cases of a wild and domestic animal. There are not wild cattle that could accidentally interbreed with our domestic cattle. Pigs have been interbreeding between wild and domestic for so long that the rare European wild boar are probably closely related to the domestic form, though they are known to be more aggressive.

The wolf, of course, is the wild form of the dog. Same species, with multiple populations, some wild, some domesticated.

So when wild Apis mellifera and domestic Apis mellifera interbred in Brazil way back in time, some of the wild traits were re-introduced to the domestic bees, and that included some increase in aggressiveness (to a more normal level) and an increase in honey production.

Aggressive African bees were accidentally released in Brazil in 1957. As “killer bees” spread northward, David Roubik, staff scientist at the Smithsonian Tropical Research Institute, began a 17-year study that revealed that Africanized bees caused less damage to native bees than changes in the weather and may have increased the availability of their food plants.

Scientists feared that dangerous swarms of Africanized bees would compete with native bees. Roubik took on the daunting task of sorting out the role of invading pollinators in tropical forests. In 1988, he set up bee traps in Sian Ka’an Biosphere Reserve–a vast area of mature tropical rainforest in Quintana Roo state on the Mexican Yucatan–with Rogel Villanueva-Gutiérrez, professor at the Colegio de la Frontera del Sur in Mexico. Africanized bees arrived in 1989.

“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. “Evolutionary relationships between bees and flowers, along with their flowering schedules, may be the fundamental currency that maintains this community.”

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.”

These results are published in the Biol. J. Linnean Soc.

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