MELBOURNE - Scientists have raised concerns following the discovery of a single gene that gives vinegar flies resistance to a wide range of pesticides, including the banned DDT.

Scientists are worried as this single mutation unexpectedly provides the fly (Drosophila sp) with resistance to a range of commonly available, but chemically unrelated, pesticides.  Significant also, is this species is rarely targeted with pesticides and many of the chemicals it is resistant to, it has never been exposed to before.

Researchers at the University of Melbourne and the Center for Environmental Stress and Adaptation Research (CESAR) that made the discovery believe the mutation arose in Drosophila soon after the introduction of DDT around the world declined.

"This is a warning that we may need to rethink our overall strategies to control insect pests," says University of Melbourne geneticist, Dr. Phil Batterham, and Program Leader for the Chemical Stress program within CESAR, a special research center that includes researchers from the Universities of Melbourne, La Trobe and Monash.

"The fact that a single mutation can confer resistance to DDT and a range of unrelated pesticide, even to those the species has never encountered, reveals new risks and costs to the chemical control of pest insects.  Unless we reassess our current methods of pest management, our future options for control may become severely restricted," he says. 

Batterham suggests that it is now imperative that research and industry focus on refining integrated pest management, which incorporates a broad arsenal of pest control measures including biological control and crop management techniques.  

The Drosophila resistance gene, named Cyp6g1, is part of a large family of genes that are found in many species, including humans.  Previous studies have implicated some members of this P450 family in pesticide resistance.  However, the function of the majority of the 90 Drosophila P450 genes is unknown.

Species will normally lose mutations that protected it against a particular pesticide once that pesticide ceases to be used.  This is because, in the absence of the pesticide, the mutation suddenly confers a disadvantage.  In this case, the Drosophila has maintained the resistance gene and is still 'fit'.  That is, the mutation does not confer any disadvantage, so it persists in the population.