Purdue Researchers Find Pesticide-Resistant Genes in Insects

May 14, 2004 - 09:39

Researchers at Purdue University recently found a set of genes that may give insects the ability to fight the effects of pesticides. The aim of the research was to develop methods of preventing insect damage to plants.

"Our study suggests that more than one gene may be involved in making insects resistant to certain pesticides," said Barry Pittendrigh, associate professor of entomology at Purdue University. "We have identified a series of genes that are interesting because the high abundance, or expression, of their genetic traits in resistant flies signifies they may be part of the orchestra that leads to resistance. But more research must be conducted before we claim whether any of these genes actually cause resistance."

Scientists examined approximately 14,000 genes from both metabolically resistant and non-resistant wild-type fruit flies, According to Purdue. The team used a recently developed technology, high-density micro-array analysis, to look at all the genes simultaneously from the drosophila, or common fruit fly. The technology makes it possible to scan the insect genome and record differences between resistant and susceptible insects.

Genes were identified that were different in resistant fly lines compared to non-resistant wild-type flies, which indicated that a number of genes might be part of the metabolic resistance-causing process. In metabolic resistance, the insect breaks down a toxin that may normally be fatal. Organisms metabolize the toxin or turn it into something that disables the harmful molecules, and then dispose of it.

"Another interesting finding that emerged from our study is that a series of genes are common to resistant insects found in the field then to those used in the laboratory," said Pittendrigh. "Hypothetically, this could lead to common genes that consistently have the same resistance traits across fly lines or even potentially across insect species."

Knowing genes involved in resistance and their relationship to each other would provide scientists with the information needed to develop ways to halt insects' detoxification of chemicals used to kill them, According to Purdue. "It would be great if we would ultimately identify a 'conductor' gene that is critical for directing the biochemical processes that allow insects to detoxify pesticides," Pittendrigh said. "A gene or genes that may be critical for resistance, in turn, may become targets enabling us to develop compounds to control pesticide-resistant insects."

Joao Pedra, an entomology doctoral student from Purdue, said that the study suggests that more than one detoxification gene is over-expressed in resistant insects. "Different resistant fly lines may also have different levels of expression of these genes. This may affect how resistant they are to a pesticide," Pedra said.

The scientists have already found that some of the genes are involved in the process of metabolizing some pesticides, rendering them ineffective. "We have a relatively firm grasp of target insensitivity-when a toxin will no longer bind with a molecule in an insect so the chemical no longer kills the insect," Pittendrigh explained. "But to date, we still don't understand many aspects of metabolic pesticide resistance."

Pittendrigh affirmed, "Finding genes involved in the fundamental resistance process that also are found across insect species may provide better resistance monitoring or even resistance management strategies."

For more information, visit www.purdue.edu.

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