As global population rises and finite resources dwindle, farmers need new, more sustainable ways to control pests. Now, ecologists have found a safe, sustainable and cost-effective new pest control. But rather than a high-tech compound or genetic technology, it’s a tiny, low-tech organism: the ant. A study on nine crops across eight countries in Africa, south-east Asia and Australia learned that ants can control pests as efficiently as–and more cheaply than–chemicals. That’s not a small matter…