Female Promiscuity Key to Pest's Success

Nov. 8, 2007 -- One of the world's most invasive agricultural pests that has devastated crops in China and Australia in recent years owes its "success" to its mating habits, a study released Thursday said.

The insect arrived in Australia and China in the 1990s through the international flower trade and has since displaced native populations of the same type in both countries.

The marauding aphids have blighted tomato and vegetable crops and in some cases spread plant viruses, forcing Australian producers to shell out millions of dollars to pay for additional supplies of insecticide.

But the invasion also intrigued entomologists who wondered how this member of the silverleaf whitefly Bemisia tabaci species -- a genetic variant known as Biotype B -- could so quickly establish its dominance in a new territory.

In Australia, for example, it took the invaders just three years to supplant the native population in Queensland and five years to do the same in the southwest of the country, according to the study published in Science.

"We were trying to find out what made B. tabaci biotype B such a successful invader and the answer appears to be sex," said Paul De Barro, a research scientist at CSIRO Entomology, Australia's national science agency in Brisbane.

De Barro and colleagues at the Institute of Insect Sciences at Zhejiang University in China conducted regular field sampling of whitefly populations in Zhejiang, China, from 2004 to 2006 and in Queensland, Australia from 1995 to 2005 to monitor the insect's behaviour as it spread and displaced native whitefly populations.