Vinegar Fly Gene Confers Pesticide Resistance

MELBOURNE, Australia, September 27, 2002 (ENS) - Scientists have discovered a single gene that gives vinegar flies resistance to a wide range of pesticides, including the banned DDT. This species is rarely targeted with pesticides, and many of the chemicals it is resistant to, it has never been exposed to before.

"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. He serves as program leader for the Chemical Stress Program within the Centre for Environmental Stress and Adaptation Research (CESAR), a special research centre 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 pesticides, even to those the species has never encountered, reveals new risks and costs to the chemical control of pest insects," Dr. Batterham said.

The Drosophila resistance gene, named Cyp6g1, is part of a large family of genes called the Cytochrome P450 genes that are found in many species, including humans.

The gene has persisted rather than disappearing as the use of DDT around the world has declined since it was banned in 1972 in the United States.

"Unless we reassess our current methods of pest management, our future options for control may become severely restricted," Dr. Batterham warned. "If this mutation was found on a pest insect, many options for the chemical control of that insect would have been removed."

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 vinegar fly has maintained the resistance gene. The mutation does not confer any disadvantage, so it persists in the fly population.

"This highlights more than ever that what we do today to control pests could irreversibly change the gene pool of that species," says Batterham.

"This research showed how easy it is for a single mutation to have such a diverse impact. A similar mutation in a pest species could have devastating consequences," he says.

The primary research was done by Dr. Phil Daborn, a former Ph.D. student under Dr. Batterham and Professor John McKenzie at the University of Melbourne. It took place in the laboratory of Professor Richard French-Constant at the University of Bath. Current University of Melbourne students Michael Bogwitz and Trent Perry contributed. Other collaborators include Professor Tom Wilson at Colorado State University and Dr. Rene Feyereisen at Centre de Recherches d'Antibes, France.

The research is published under the title, "Why Bugs Resist Insecticides," in the current edition of the journal "Science," a publication of the American Association for the Advancement of Science.