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Sexual hormone (pheromones) diffuser in a Swiss vineyard

BERN, SWITZERLAND – The headline from Bern, “25 years of sexual confusion in Switzerland” is a clear winner for waking up editors, but those in the world of wine will be less surprised than others: sexual confusion aimed at grapevine pests has significantly reduced the use of chemical insecticides.

The sexual confusion method used by wine grape and other fruit growers to fight their main ravagers was put into use in 1986 and today it’s used by nearly 60 percent of grape growers and more than 50 percent of other growers, in particular berry and orchard farmers, to good effect.

Switzerland has become the world leader for using this method to fight fruit pests, in terms of the percentage of planted surface area that employs it.

The principle behind it is simple: large quantities of pheromone, the female sexual hormone of the pests, is diffused throughout the fruit-growing area, and the males, overwhelmed by the presence everywhere of this naturally produced hormone, fail to find and fertilize the females. The number of ravagers is, as a result, greatly reduced.

The method is precisely targeted at specific pests so remains completely inoffensive to other creatures and plants.

The efficacity of nematode pheromones diffusion, bottom, has been greater than that of insecticides, top, at keeping down the grapevine pest population

The federal research station, Agroscope Changins-Wädenswil ACW, reports that the method has proved efficient after 25 years, with vineyards that diffuse nematode (a grapevine worm) pheromones having a far smaller number of the pests than vineyards that use chemical insecticides. Nematodes have become increasingly resistant to insecticides.

The hormonal pest-fighting approach initially ran into some difficulties because the system was relatively expensive and there were problems installing it, but over time the cost has gone down and the system has been simplified. Today, walking through grapevines in Vaud and Valais in particular, you can quickly spot the small containers at the ends of vines. The federal research station says it is now working on biodegradable products that will be yet cheaper and easy to set up.

French-speaking Switzerland’s vineyards, the largest wine grape growing area in the country, has virtually entirely converted to the sexual confusion method.

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