Tuesday, November 20, 2007

Invasion of the Flies!

In recent years a pest new to China and Australia has devastated crops and cost farmers millions of dollars. The invasive insect, believed to originate in the Middle East and Mediterranean, is a genetic variant of the native silverleaf whitefly Bemisia tabaci species, called "Biotype B." Biotype B flies have taken over an entire area of Australia in only 3 years and scientists have been wondering how this rapid population success occurred. It turns out it all has to do with a very unique mating system.

This species of fly (both the invaders and native flies) are haplodiploid meaning that all unfertilized eggs give rise to male offspring and all fertilized eggs give rise to female offspring. When the two populations come together they attempt to mate but their slight differences make fertilization impossible. Eggs are therefore left unfertilized, producing disproportionate amounts of male offspring. The two types of females respond to this drastic increase in potential mates in two different ways. The native females continue to mate normally with males, whereas the invader females become more promiscuous and mate with many males, producing a boom in the female population.

In addition to this rapid Biotype B population growth, it's also noteworthy that males of the invasive species still mate with native females, making native flies less likely to be mating with eachother. These elements combined have led to huge changes in the relative population sizes of these types of flies, and as the number of Biotype B female flies increases, the number native female flies decreases. In the long term this could mean extinction for China and Australia's native fly population.

Posted by Christina Breed (9)


At 6:58 PM, Blogger Kyle said...

This comment has been removed by the author.

At 6:59 PM, Blogger Kyle said...

Neat! I wonder why the invading fly happens to have this mating attribute. It seems that it must have developed to deal with other aphid species in the Middle-east or Mediterranean. The short amount of time they have been in China and Australia makes it seem like it must have been an attribute they already developed earlier on in their evolution. Good post, interesting topic!!

Posted by Kyle McCarthy (9)


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