Scientists try 'outsmarting' crop pests

Afghanistan Sun Friday 9th April, 2004

U.S. researchers said they have developed a new screening method aimed at boosting pesticide effectiveness.

The researchers, at Purdue University, said the process is designed to identify chemical compounds that could be

added to current pesticides to overcome resistance insects have developed to them.

The team studied common research fruit flies, Drosophila melanogaster, because they knew the molecular mechanism that provides the insect with chemical resistance. They applied that knowledge to test known chemicals' toxicity to the resistant insects.

They then tested nine related insecticides in order to identify a negative cross-resistance toxin. They found

the resistant flies were highly susceptible to one compound called deltamethrin. Use of deltamethrin dramatically reduced the numbers of pesticide-resistant insects in a fruit fly population.

Crop-damaging insects mutate over time so they are able to overcome the effects of chemicals developed to kill them. A toxin that protected a crop for more than a decade or two eventually may lose its lethality due to resistance in the insect population.

According to the U.S. Department of Agriculture, more than $7.5 billion is spent annually on agricultural pesticides, or up to 50 percent of the costs involved in managing harmful insects.