John Pickett is head of the Biological Chemistry Department, and scientific director of the Centre for Sustainable Pest and Disease Management, at Rothamsted Research (UK). This expert in organic chemistry has become a world authority on semiochemicals, which are natural volatile substances that affect the behaviour and development of living organisms. He plays a leading role in the move away from the traditional use of wide-spectrum pesticides to more precise control through compounds targeting specific pests at critical stages in their life cycles. Recent successes include a programme for controlling weeds and crop pests. In Africa, thousands of subsistence farmers have already adopted pest control systems based on natural chemical compounds.