RESUMO
BACKGROUND: For more than 30 years, the main strategy to control illicit coca crops has been forced eradication. Despite the importance of social investment and persistent poverty in areas where illicit crops are grown, there is no empirical evidence of the effect of social expenditures on preventing and reducing the expansion of illicit crops. METHODS: This paper analyses how social investment in conjunction with eradication affects new coca crops. The model is tested using a dataset consisting of annual data for 440 contiguous municipalities that had coca in any year between 2001 and 2010. The analysis includes the two main techniques used to control illicit crops, manual eradication and aerial spraying. RESULTS: Aerial spraying is effective in deterring farmers from increasing the size of their new coca fields, but this effect is small. Social investment, in addition to generating social welfare, has a significant negative relationship with new coca crops, 0.09-hectare reduction in new coca crops per additional 50-cent spent in social investment (human capital and infrastructure) per inhabitant. CONCLUSION: Social investment emerges as a complementary and effective strategy to control illicit crops.