Sex among the tomato plants in a greenhouse!

The South American Tomato Leafminer was first found in Europe in Spanish crops in 2006 and has since spread through Europe. An amazing technique to combat this pest is now being deployed by professional tomato growers. It’s called ‘mating disruption’ and uses insect sex pheromones which are chemical messengers emitted by females to attract males from long distances in order to mate. 

By flooding the greenhouse with this irresistible pong (from the point of view of the male South American Tomato Leafminers) the males become so confused that they never find a female to mate with. No mating means no next generation of leafminers and so the tomato crop escapes damage from the pest and both the grower and the consumer are happy. Perhaps the title above should read: No sex please we’re British tomatoes!

Almost all tomatoes in Britain are grown in heated glasshouses. They are produced in our natural season and harvested between March and November. Food safety and environmental protection are absolute priorities for British growers. Few, if any, pesticides are used on British tomato crops and the Tomato Growers Association’s objective is to eliminate all such use within 10 years. British tomato growers were the first to use natural enemies of pests, rather than chemical sprays, as a way to control them. 

Each pest has its own predator or parasite, sometimes more than one, which lives on it, and growers have had to become highly skilled at monitoring their crops to pick up a pest attack at an early stage. They also have to maintain a balance between the ‘bug busters’ introduced to the crop and the pests.

The use and development of effective biocontrol methods has been a key factor in the continuing reduction in both the use of pesticides and the minimisation of pesticide residues. This simple system is very effective. Pests have become resistant to many insecticides so they no longer work. Another bonus is that consumers and glasshouse staff now rarely come into contact with pesticides and neither do the two million bumblebees used to pollinate the 500 or so acres of British glasshouse tomatoes.

Written by: Joanna Wood