how Flies and worms they protected?
Answers
Animals must wage a never-ending war against parasites, constantly evolving new ways of resisting these threats. Resistance comes in many forms, including genes that allow their owners to shrug off infections. But one species of fly has developed a far more radical solution – it has formed a partnership with a bacterium that lives in its body and defends it against a parasitic worm. So successful is this microscopic bodyguard that it’s spreading like wildfire across America’s besieged flies. The fly Drosophila neotestacea is plagued by a nematode worm called Howardula. Around a quarter of adults are infected and they don’t fare well. The worm produces thousands of young in the body of its hapless host, and the little worms make their way into the outside world via the fly’s ovaries. Not only does this severely slash the fly’s lifespan, it also always sterilises her. But according to John Jaenike from the University of Rochester, the fly is fighting back. In the lab, he showed that worm-infected flies retained their fertility if they were also infected with a bacterium called Spiroplasma (below). The same was true in the wild – females carrying the bacteria and the worm were more than 10 times more fertile than those that just bore the worm. In some way, Spiroplasma hampers the growth of Howardula, halving the size of female worms who shared a fly with them.