Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances
Authors: Alessandro Gentile
Ann B Swengel
Roel van Klink
Jonathan M Chase
Konstantin B Gongalsky
Diana E Bowler
Journal: Science (2020)
Discipline: Multidisciplinary
Keywords: insect abundances; long-term surveys; trends; terrestrial insect abundance; freshwater insect abundance
Affiliations: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany. ., Leipzig University, 04109 Leipzig, Germany., WBBS Foundation, 9409 TV, Loon, Netherlands., German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany., Institute of Biodiversity, Friedrich Schiller University Jena, 07743 Jena, Germany., Helmholtz Centre for Environmental Research (UFZ), 04318 Leipzig, Germany., A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow 119071, Russia., M.V. Lomonosov Moscow State University, Moscow 119991, Russia., Independent researcher., Department of Computer Science, Martin Luther University-Halle Wittenberg, 06099 Halle (Saale), Germany.

Abstract:  Recent case studies showing substantial declines of insect abundances have raised alarm, but how widespread such patterns are remains unclear. We compiled data from 166 long-term surveys of insect assemblages across 1676 sites to investigate trends in insect abundances over time. Overall, we found considerable variation in trends even among adjacent sites but an average decline of terrestrial insect abundance by ~9% per decade and an increase of freshwater insect abundance by ~11% per decade. Both patterns were largely driven by strong trends in North America and some European regions. We found some associations with potential drivers (e.g., land-use drivers), and trends in protected areas tended to be weaker. Our findings provide a more nuanced view of spatiotemporal patterns of insect abundance trends than previously suggested. 

Retracted: No

PubPeer comments:
 Letters to the editor: https: science.sciencemag.org content 368 6489 417 tab-e-letters Further discussion: https: onlinelibrary.wiley.com doi full 10.1002 wat2.1506 , 
 The original authors replied to the comment on this paper published in *WIREs Water* here: https: wires.onlinelibrary.wiley.com doi full 10.1002 wat2.1501 One of their responses is that  we never suggested that there was a globally increasing trend of freshwater insect abundances, but only spoke of an average increasing trend in the available data. This seems disingenuous given that their original Science paper was entitled  Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances ; clearly publishing such a title, in such a journal, is going to strongly imply to people who do not take the time to read the paper that the trends identified are global. If the authors, and journal editors, were serious about accurately communicating a nuanced message, then why not use a title that makes the limits of the paper clear? For example, why not  Available, but unrepresentative, evidence suggests that... If we are concerned about the messages that the media and others take from our papers, then perhaps we should start with the thing they see first, namely the paper title? ,