Chemical agents have been employed in pest control for centuries, but during the second half of the nineteenth century their use intensified considerably. The increasing international commerce of seeds and crops, the expansion of monoculture across the planet, and the new modes of circulation provided by the new motorized transports (trains, cars, modern ships) led to a global spread of new pests, which explains, at least in part, the intensification of the use of chemical pesticides in agriculture. At the turn of the twentieth century, the use of arsenic compounds, copper salts and nicotine extracts was already a common practice in many parts of the world. Moreover, these agents were part of the processes of specialization and intensification in agriculture, which introduced new forms of land ownership and mechanized production and also expanded the modes of irrigation, the use of agrochemicals such as synthetic fertilizers and herbicides, and plant breeding techniques. Since the end of the World War II, synthetic pesticides have been essential elements of the intensification of agriculture and the so-called Introduction.