Quantifying rapidly declining abundance of insects in Europe using a paired experimental design

Abstract The abundance of insects has decreased for the last decades in many parts of the world although so far few studies have quantified this reduction because there have only been few baseline studies dating back decades that have allowed comparison of ancient and recent population estimates. Such a paired design is particularly powerful because it reduces or eliminates bias caused by differences in identity and experience of observers, identity of study sites, years, time of season, and time of day, and it ensures identity of sampling procedures. Here, I compiled information on the reduction in abundance of insects in Europe and Algeria by the same persons compiling the abundance of insects from the same 21 study sites during 1951–1997 and again a second time in 1998–2018. There was a reduction by 47% in the abundance of insects. The difference in abundance in old compared to new samples declined with latitude, with a significant variance among taxa. This reduction in abundance of insects was of such a magnitude that it must have consequences for insectivores and the role that insects play in ecosystems.

Abstract licence: CC BY

1. 10.

   Rapid declines of common, widespread British moths provide evidence of an insect biodiversity crisis · 2006

2. 12.

   Long-term decline in abundance and distribution of the garden tiger moth ( Arctia caja ) in Great Britain · 2002

3. 14.

   Declines in insectivorous birds are associated with high neonicotinoid concentrations · 2014

4. 18.

   Long‐term changes in the abundance of flying insects · 2009

5. 20.

   Long‐term changes to the frequency of occurrence of British moths are consistent with opposing and synergistic effects of climate and land‐use changes · 2014

6. 25.

   More than 75 percent decline over 27 years in total flying insect biomass in protected areas · 2017

7. 28.

   Experimental heatwaves compromise sperm function and cause transgenerational damage in a model insect · 2018

26 more references, whose wording the paper’s licence keeps private.

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.