While trying to come up with a pesticide solution to kill off bollworms, Dr Robert Mensah had his eureka moment. It was the 90s, and in Australia bollworms were devastating cotton farms. He experimented and eventually came up with a simple food spray, "a mixture of food ingredients, yeast and sugar-based, diluted in water and applied to crops. It emits an odour which is picked up by beneficial predatory insects and attracts them to the fields where they kill pests." It was the beginning of an international grassroots campaign, in which Mensah has worked with various charities to teach people about this sustainable farming method. Ever since the dangerous side effects of pesticides became widely known, alternatives have been sought. This approach to farming, which reduces our reliance on pesticides, is called integrated pest management. In 2005, Mensah took food sprays to Benin, where the Pesticide Action Network (PAN UK) was helping farmers transition to organic farming. There, the misuse of chemical pesticides was seriously damaging people's health. The food sprays cheap, safe and effective " caught on with farmers in Benin where thousands now use the technique. From there, Mensah took food sprays to southern Ethiopia, where they were also trialled successfully on vegetables ... and then to Vietnam where they were used successfully on maize. Another charity, Better Cotton, is now trialling food sprays in India ... where they've trained 214,000 farmers to use sprays.