This week we go green as Alison Smith discusses how algae get their vitamin B12, Tim Upson reveals the science behind composting, Heather Gorringe and Richard Fishbourne dish the dirt on what worms get up to in your compost heap, and John Pickett talks about natural mosquito repellents. Sticking with the insect theme, Nigel Franks describes how the first example of animal teaching has been found in ants, while in Kitchen Science, Derek is itching to reveal how ants lay chemical trails to their food. Like this podcast? Please help us by supporting the Naked Scientists)