A very strongly worded, meta-review paper (looking at 73 historical reports from around the world published over the past 13 years) has just been published looking at the fate of insects around the world. The researchers have collated other people’s research, including the big 27 year study from Germany, that showed 75% loss of insects by weight (biomass). The basic headlines are quite scary: 40% of insect species are declining; 33% are endangered; we’re losing a total mass of 2.5% of insects every year. The reviewers blame habitat loss by conversion to intensive agriculture as the main driver for the declines, plus agro-chemicals, invasive species and climate change adding to the burden. Adam Rutherford speaks to insect expert Professor Adam Hart from the University of Gloucestershire to discuss numbers and consequences.

It’s quickly being realised that the composition of microbes in our guts is vital to our health. Scientists working on the gut microbiome have discovered and isolated more than 100 completely new species of bacteria from healthy human intestines. It’s hoped that these new techniques to isolate and grow these novel bugs, will give us insight into how our microbiome keeps us healthy.

After covering the story about the Earth’s early core accretion and the clues found in rocks about the early magnetic field, listener Neil Tugwell emailed BBC Inside Science to ask for more information about geomagnetic switching. Are we heading for another flip of the magnetic poles? And what might be the impact on GPS? Adam gets the answers from Dr. Robert Wicks, lecturer in space risk in the UCL Institute for Risk and Disaster Reduction.

Producer: Fiona Roberts