Most of us don’t give much consideration to some of the smaller participants of our everyday life – the insects. They’re a constant facet of daily existence, even when relegated to background noise. But if you can think back to the presence of insects in your life, maybe ten, fifteen years ago, was it different? Even if you can remember longer than twenty-seven years ago, you might not be able to say with absolute certainty that there’s been about a 76-82% decrease in the biomass of aerial insects, but you’ve probably noticed a pretty significant shift in the sheer number of bugs you encounter in a day. The cicadas don’t sing quite as loud at night, the buzzing of flies is a less frequent annoyance, and you’ve definitely been cleaning fewer bugs off your windshield in recent times.
Scientists of one German entomological society, however, can say with certainty that in the last twenty-seven years there’s been a 76-82% decrease in the biomass of aerial insects at natural areas across Germany . Similar studies across the world have been less singularly focused on insect disappearances, but many have noted similar trends in biomass declines . A decrease in overall biomass is a different conversation than one strictly about biodiversity and species extinction, but the effects are just as threatening to earth’s ecosystems and warrant some serious inspection.
The German study that incited these worries of a so-called “Insect Armageddon” began collecting data of aerial insect biomass at ninety-six protected areas in 1989, and the experiment continued until 2016. Scientists were baffled by the drastic results – over a 75% drop – which far outpaces the global estimate of 58% decline of vertebrates from 1970-2012 . They also found that biomass loss is the highest in the summer, and is occurring across all habitats. Shockingly, at the moment there seems to be no clear-cut main cause of this massive decline. Climate change and human land use were initially suspected as major factors, but the study did not produce enough evidence for a direct correlation between either of them. Agricultural intensification seemed to have a stronger effect on the losses, but again, not substantial enough to be the sole cause of this devastation .
Insects compose an enormous portion of one of the primary trophic levels. They are pollinators, decomposers, population controls, and a key part of nutrient cycling . This massive decrease in their biomass – explicitly localized to natural areas of Germany in this study, but noted all the same by scientists around the world – affects everything else that lives in this world, from tiny plants to megafauna and even humans. A world without insects would be uninhabitable for a large percentage of all organisms alive today – and a very quiet place indeed.
(1) Hallmann, C. A.; Sorg, M.; Jongejans, E.; Siepel, H.; Hofland, N.; Schwan, H.; Stenmans, W.; Müller, A.; Sumser, H.; Hörren, T.; Goulson, D.; de Croon, H. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoS ONE 2017, 12 (10).
(2) Jarvis, B. The insect apocalypse is here. The New York Times Magazine. November 27, 2018.