Insects affected both in grasslands and forests

The researchers collected more than one million insects at 300 sites. They were able to prove that many of the nearly 2700 investigated species are in decline. In recent years, certain rare species could no longer be found in some of the regions studied. Both in forested areas and grasslands, the scientists counted about one third fewer insect species after 10 years.

"Before our survey it was unclear whether and to what extent forests were affected by the insect decline as well," says Seibold. Since 2008 they measured a decrease of approximately 40 percent in insect biomass in the forests they studied. In grasslands the results were even more alarming: at the end of the study period, the insect biomass decreased to only one third of its former level.

"A decline on that scale over a period of just 10 years came as a complete surprise to us – it is frightening, but fits the picture presented in a growing number of studies," says Wolfgang Weisser, professor of Terrestrial Ecology at TUM and a co-initiator of the cooperative project.