Although it was known species such as bees and butterflies were declining, scientists were left shocked by the drop in numbers across nature reserves in Germany. The authors urge further investigation of causes for this decline, its geographical extent, and how its potential impact on the ecosystem.
Understanding insect numbers and the reasons behind changes to them is therefore vital to ensuring food security.
Published in the journal Plos One, the study is based on data gathered by dozens of amateur entomologists who used special traps that ultimately snagged more than 1,500 samples of insects.
Since 1989, scientists have been trapping insects in large tents, called malaise traps, and measuring the total biomass.
Mr Goulsen said a possible explanation would be insects dying when they fly out of nature reserves into farmland "with very little to offer for any wild creature".
At 82 percent, the decline of insects biomass during midsummer, when insects populations tend to peak, proved more severe than the annual average decline. "While some temporal changes in climatic variables in our study area have taken place, these either were not of influence (e.g. wind speed), or changed in a manner that should have increased insect biomass (e.g. temperature)". They also recommend the creation of preserves that don't border agricultural land.
Ecologists from Radboud University, in Nijmegen, the Netherlands, who worked with German and English colleagues including Dave Goulson, a professor at the University of Sussex, said that the rate of loss was not sustainable. "Insects make up about two thirds of all life on Earth", he said.
'We appear to be making vast tracts of land inhospitable to most forms of life, and are now on course for ecological Armageddon. "On current trajectory, our grandchildren will inherit a profoundly impoverished world".
"All these areas are protected and majority are well-managed nature reserves", said Caspar Hallmann at Radboud University and part of the research team, "yet, this dramatic decline has occurred".