Jan. 13, 2006 — African locusts were early pioneers that colonized the New World several million years ago, according to a genetics study.

The research, described in the latest issue of the journal Proceedings of the Royal Society of London, solves a long-standing puzzle: why the closest relatives of the African desert locust (Schistocerca gregaria) are found in the New World, rather than in Africa.

Indeed, the Western Hemisphere harbors about 50 different species of the same group.

An agricultural pest since biblical times, desert locusts form massive swarms that migrate long distances and decimate crops.

To build the evolutionary history of the insects, Nathan Lovejoy, of the University of Toronto at Scarborough, and colleagues analyzed mitochondrial DNA, which is passed down on the female line, from the powerful hind leg muscles of more than 20 species of locusts.

It emerged that Schistocerca gregaria is not closely related to any particular subset of Western Hemisphere Schistocerca species: like humans, the desert locust probably came out of Africa.

"Our DNA study provides evidence that approximately three to five million years ago, a swarm of locusts managed to fly across the Atlantic, from Africa to the Americas, where it gave rise to a diverse group of species," Lovejoy told Animal Planet News.

According to Lovejoy, an invading population from north Africa probably arrived in Central and South America and very soon thereafter colonized the Galapagos Islands and, subsequently, North America.

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