Observations of changes in the abundance of one group of insects tell very little about how other insect species behave, even in the same ecosystem. Different groups of insects may show similar trends in one location, but different trends in other locations. These are the results of a new meta-analysis of years of insect data from more than 900 localities around the world. The study, published in Biology Letters, was conducted by a team of researchers from the German Center for Integrative Biodiversity Research (iDiv), Martin Luther University of Halle-Wittenberg, Friedrich Schiller University Jena, the Helmholtz Center for Ecological Research and the A.N. Severtsov Institute of Ecology and Evolution RAS. It highlights the importance of monitoring multiple species simultaneously to provide guidelines for insect conservation policy.
Insect declines became the subject of global debate in 2017 when scientists reported a loss of three-quarters of the biomass of flying insects from West German nature reserves in 30 years, showing a trend of general decrease in insect biomass around the world. Since then, many studies have appeared from around the world, often showing significant declines in numbers, giving rise to hundreds of popular papers on the problem of insect decline.