Invading animals disrupt nature’s balance

November 14th, 2007 - 10:24 am ICT by admin  

Scientists have come forward with the new study after examining the silverleaf whitefly (SLW), Bemisia tabaci biotype B. In many regions of both countries, native types of B. tabaci have been replaced by the invasive B biotype.

“This insect has spread from its Mediterranean-Asia Minor home range so successfully that it is now a global pest. It has even made it into the top 100 invasive species,” said Professor Liu Shu-Sheng from the Institute of Insect Sciences at Zhejiang University in China.

According to the new study, invasive animals often thrive at the expense of their close indigenous relative because of their unique sex life.

“We were trying to find out what made B. tabaci biotype B such a successful invader and the answer appears to be sex,” said Dr Paul De Barro from CSIRO Entomology. “Whiteflies have an interesting sex life. Males are produced from unfertilised eggs and females from fertilised eggs,” he added.

“The different biotypes of B. tabaci look so identical that when the B biotype invades, they can’t tell each other apart. However, matings between the different types aren’t successful and this leads to an increase in the number of unfertilised eggs. So the first phase of invasion involves an increase in male offspring,” said Dr De Baro.

In response to this increase in males, the invasive females become more promiscuous. And more frequent sex with the excess B biotype males leads to an increase in female offspring.

“To add insult to injury, the B biotype males are also more aggressive than the indigenous males. This means they displace the locals and cause mating interference between local males and females,” Dr De Barro explains.

The end result of this unusual mating practice is a takeover of indigenous B. tabaci by the alien invaders, which results in lowering the population of the native species. (ANI)

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