8 September 1999

The possibility of less pesticides from Down Under

by Kate Melville

Australian researchers are using the molecules in pests' own hormones to develop more 'environmentally friendly' ways to defeat them.

The research is based on ecdysone, an insect hormone that regulates the moulting process. The shell cannot grow as the insect grows, so it has to be shed at various times during the normal life cycle.

Once the scientists have described the structure of receptors on the hormone for certain insect pests they will be able to design molecules to block the hormone from working. This will mean that the insect fails to moult and dies.

The research into this new approach to the development of crop protection agents has been conducted by the C.S.I.R.O. and is similar to that used for the development of Relenza™ the world's first effective 'flu drug (developed by the Australian company Biota in conjunction with Glaxo Wellcome). According to the team leader, Dr Paul Savage, "We used the approach of looking at the molecular structure of the 'flu virus to find a way to block it from working and thus create the 'flu drug. We're now looking at using the same technique to beat insect pests.

Because the structure of the receptors varies from one insect species to another, the new agents can be targeted to specific pests such as flies or plant sucking bugs. This will have considerable safety and environmental benefits because the new products will not affect anything other than the target insects. Humans, mammals, birds or most other insect groups will not be affected."

The new agents will be more efficient and therefore will require lower applications of pesticide- it will also be quicker to develop and register the new agents.

Over the last 40 years the total area of land under crops has not changed much, but the output has trebled. Much of this has been accomplished by the use of chemical pesticides. "If we are to maintain the high crop yields we need to constantly keep ahead of pests," Dr. Savage says.

Given that the markets for crop and animal protection are worth billions of dollars a year, it will be interesting to see how this research is commercialised and with whom - presumably not a small Australian company, but with one of the usual suspects in the international agro-chemical world?