Jatropha curcas is grown as a biofuel crop in the tropics, and in many parts of Africa it also has a number of domestic uses, e.g. it is frequently grown as a hedge. The collapse of the biofuels market in Zambia has inspired a search for alternative uses for this plant. Previous laboratory studies suggested that Jatropha exhibits a range of beneficial properties, including pesticidal properties. In this paper, we report a series of studies aimed at testing whether formulations of Jatropha powder or oil are effective against storage pests infesting cowpeas and maize. These include laboratory experiments in the UK and field studies conducted with village farmers in Zambia. We report these findings, and discuss the role of participatory research in aiding the adoption of locally-grown botanical pesticides amongst resource-poor farmers in rural Zambia.