As human activities rapidly transform the planet, the global insect population is declining at an unprecedented rate. In the UK, a recent survey suggested the number of flying insects have fallen by almost 60% in less than 20 years. Some are calling it an impending 'insect apocalypse'. Their disappearance matters because insects are the most diverse group of organisms on the planet and the foundation of every freshwater and land based ecosystem. They provide food for birds, bats and small mammals; they pollinate around 75% of the crops in the world; they replenish soils and keep pest numbers in check. You may not always like insects in your personal space but you certainly need them to survive. Insect population collapses could mean significant crop failures, collapsing food webs, bird extinctions, disease outbreaks and more. We're going to explore why it's happening and what can be done to mitigate it. Shaun Ley is joined by: Dr Erica McAlister - Principal curator of fleas and flies at the Natural History Museum in London and an honorary fellow of the Royal Entomological Society. Dr David Wagner - Professor of ecology and evolutionary behaviour at the University of Connecticut where he specialises in caterpillars, butterflies, moths, insect conservation and global insect decline. Oliver Milman - US environment correspondent for The Guardian newspaper and author of The Insect Crisis. Also in the programme: Dr Kendra Klein - senior staff scientist with Friends of the Earth in the United States. Julian Little - a plant biochemist with 35 years of experience in the agricultural industry including time as head of communications for Bayer in the UK. (Image: A butterfly rests at the Butterfly Garden in Konya, Turkey. Credit: Serhat Cetinkaya/Anadolu Agency via Getty Images)