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Daily News Archive
From August 12, 2005

DDT-Resistant Insects Found To Have Genetic Advantage
(Beyond Pesticides, August 12, 2005) Scientists at the University of Bath in the UK announced on August 9, 2005 that new studies show DDT-resistance to be a double advantage for fruit flies. The study showed that DDT-resistant fruit flies and their offspring were more likely to thrive than non-resistant fruit flies, even after spraying has ended.

It has been long accepted that most pesticide resistance in bugs comes with a genetic disadvantage; that when application of the pesticide is reduced or stopped, non-resistant bugs will overcome the resistant bugs and resistance will eventually phase out of the gene pool. But the new study released from the University of Bath proves exactly the opposite. “We found that DDT resistance in fruit flies not only carries no cost but in fact confers an advantage when inherited through the female,” Richard ffrench-Constant, PhD, the researcher who led the study, commented in a press release.

The experiment was highly controlled with researchers making sure that all the flies were genetically identical with the exception of the DDT-resistance gene. Observations were made of the survival and development rates of both resistant and non-resistant offspring at all stages of life.

Another interesting discovery was that some resistance strains exhibited “cross-resistance” to other compounds. This means that the bugs can not only build up resistance to the pesticide being sprayed, but in doing so can also create a resistance to other pesticides that may be sprayed to overcome resistance. Thus there is a large potential of creating widely resistant super bugs that do not respond to any pesticide or insecticide sprays.

The issue of pesticide resistance in bugs is particularly important right now with malaria killing over 1 million people worldwide every year and the ongoing threat of West Nile Virus.

For more information on effective mosquito control strategies visit our West Nile Virus Mosquito Management program page.