Scientists employ sex in war on aphids

THE SCENT of a female aphid could bring relief to rose growers wary of chemical pesticides, according to scientists working on the latest in gardening technology, writes Susan Watts.

Chemists are enlisting sex pheromones to distract male aphids, entrap them and infect them with a fatal fungus. Scientists have identified and manufactured versions of the sexy smells of several aphids - mainly those that attack commercial crops. Now they are coming to the aid of the domestic gardener.

'We should have tracked down the first rose aphid pheromone by the end of the year,' Professor John Pickett, from the Agricultural and Food Research Council's Rothamsted experimental centre in Hertfordshire, said yesterday at the annual Chemical Congress of the Royal Society of Chemistry, Southampton.

The idea is to hit the aphids when they are most vulnerable. Rose aphids spend most of their time on herbaceous plants, where can they reproduce asexually. But they only reproduce with a partner on the woody rose tree. 'That's the stage when you can divert the males,' he said.

The research is still at an early stage, although he anticipates a product will be available in three to four years time.

Professor Pickett's approach seeks a benign way to control pests, although he pointed out that biological pest control can be frightening. Another speaker at the congress talked about the use of tiny worms to control slugs. The worm infects the slug with a bacterium that multiplies until the slug explodes.

'It can be really quite unpleasant, this biological control stuff,' Rose Ward from the Consumers' Association, said.