Neem, India

In rural India, neem, with its smorgasbord of antimicrobial properties, is used as a remedy for almost every ill. And its leaves, bark and oil contain a biochemical battery of insect repellents and steroid-like chemicals, which simultaneously disrupt different aspects of an insect’s life, making it harder for them to evolve resistance to it. Given this, perhaps the most perplexing question is why it isn’t in wider use around the world. Neem has a long tradition of use, which makes it difficult for commercial firms to patent. Without being able to protect a product from competition, those firms have little incentive to pay for regulatory approval of neem-oil products and can more profitably sell patentable synthetic chemicals. The free market doesn’t always get it right.