( Insects that can withstand the powerful...)DDT-resistant insects have additional genetic advantage that helps resistance spread

This discovery overturns current theories that resistance to pesticides burdens insects with a genetic disadvantage that would stop them from competing with non-resistant insects once farmers stop using that pesticide.

Instead, researchers now believe that fruit flies that develop resistance to DDT gain a two-fold advantage: not only can they survive being sprayed with pesticide, which other insects cannot, but in doing so they develop a genetic advantage that makes them and their offspring more likely to thrive even when spraying is abandoned.

Researchers warn that the same process may be going on when doctors across the world prescribe antibiotics to cure infections. Antibiotic resistance may potentially confer the same kind of genetic advantage to 'superbug' bacteria, and measures such as preventing certain antibiotics from being prescribed may not halt the spread of antibiotic resistance in bacteria.

"We found that DDT resistance in fruit flies not only carries no cost but in fact confers an advantage when inherited through the female," said Richard ffrench-Constant (correct), from the University of Bath, who led the study.

"This suggests that by becoming DDT resistant the female flies are passing on some unknown advantage to their progeny, presumably associated with the single metabolic enzyme (cytochrome P450) that they over express.''

"These results are important for the use of any drug, pesticide or antibiotic as they suggest that resistance will not always go away when we do not spray or prescribe antibiotics."

Scientists had previously believed that the genetic 'cost' of resistance would mean that DDT resistance would dwindle once the
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Source:University of Bath