Genetic Pesticide for Termites Developed in Florida

Pest control industry estimates peg the damage termites cause at more than $5 billion each year, despite the many insect control techniques aimed at them. And homeowner's insurance will not cover these claims.

Pesticide experts believe that insect control methods designed to affect the genes of target pests are the future of insecticides because of their effectiveness and the fact that they do not affect other creatures.

"The trend in insect control is to find methods that eliminate the problematic insect without affecting anything else in the environment," said Michael Scharf, the entomologist with the UF Institute of Food and Agricultural Sciences who is developing the genetic pesticide.

Termites destroy billions of dollars worth of wooden structures each year. (Photo courtesy The Master Gardeners)

"What could possibly be more specific than genes that are unique to the insect itself?" he said.

In a paper published online this week in the journal "Insect Biochemistry and Molecular Biology," Scharf describes the effects of a mixture that, when consumed by termites, causes them to be cripplingly deformed after molting.

The active agent in this "genetic pesticide" is ribonucleic acid, or RNA. These strands of genetic material carry the instructions encoded in deoxyribonucleic acid, or DNA, an acid that contains the genetic instructions used in the development and functioning of all known living organisms.

Scharf and his team analyzed part of the termite genome and picked a gene that would disrupt the insect's life cycle and is found only in that type of termite.

They then crafted an RNA structure that would interfere with that specific gene's RNA, thus silencing the gene's activity.

Termites have their skeletons on the outside of their bodies. In order to grow larger they must periodically shed this exoskeleton in a process called molting.

The research termites showed severe deformations after molting as a result of ingesting the gene-silencing pesticide designed by Scharf and his team.

RNA interference techniques are not new - they are commonly used at genetic research institutions across the nation to discover what an organism's gene does by silencing it and observing what occurs

Despite termites' susceptibility to RNA interference, any marketable genetic pesticide is still many years away from development, Scharf said.

Still, when genetic pesticides are ready for market, they may solve the problem of resistance that insects develop to chemical pesticides designed to eliminate them from fields and crops.

Adaptation to genetic pesticides would be more difficult for farm pests than adaptation to chemical pesticides, scientists theorize.

Controlling termites, including the highly destructive Formosan termite now spreading through Florida and the Southeast, is becoming more problematic. Lumber pressure-treated with chromated copper arsenate was widely used, but it is being phased out because arsenic is a known carcinogen.

While chemical barrier treatments under and around the foundation are effective, they deteriorate over time and must be reapplied about every five years.

The pesticide chlordane, which was used to control termites, was banned by the U.S. Environmental Protection Agency in 1985 because of risks to the environment and to the human nervous system. Now that chlordane is illegal, interest in termite ecology has increased because of the need for a safe alternative to the chemical.

In addition, at the U.S. Department of Energy's Joint Genome Institute scientists are sequencing the termite genome to reveal biological processes that could be keys to converting woody cellulosic materials into alternative fuels.

They hope to synthesize the novel enzymes discovered through this project to accelerate the delivery of the next generation of cellulosic biofuels.

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