Interpreting insect declines: seven challenges and a way forward

Raphael K. Didham*, Yves Basset, C. Matilda Collins, Simon R. Leather, Nick A. Littlewood, Myles H.M. Menz, Jörg Müller, Laurence Packer, Manu E. Saunders, Karsten Schönrogge, Alan J.A. Stewart, Stephen P. Yanoviak, Christopher Hassall

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

235 Citations (Scopus)
148 Downloads (Pure)


Many insect species are under threat from the anthropogenic drivers of global change. There have been numerous well-documented examples of insect population declines and extinctions in the scientific literature, but recent weaker studies making extreme claims of a global crisis have drawn widespread media coverage and brought unprecedented public attention. This spotlight might be a double-edged sword if the veracity of alarmist insect decline statements do not stand up to close scrutiny. We identify seven key challenges in drawing robust inference about insect population declines: establishment of the historical baseline, representativeness of site selection, robustness of time series trend estimation, mitigation of detection bias effects, and ability to account for potential artefacts of density dependence, phenological shifts and scale-dependence in extrapolation from sample abundance to population-level inference. Insect population fluctuations are complex. Greater care is needed when evaluating evidence for population trends and in identifying drivers of those trends. We present guidelines for best-practise approaches that avoid methodological errors, mitigate potential biases and produce more robust analyses of time series trends. Despite many existing challenges and pitfalls, we present a forward-looking prospectus for the future of insect population monitoring, highlighting opportunities for more creative exploitation of existing baseline data, technological advances in sampling and novel computational approaches. Entomologists cannot tackle these challenges alone, and it is only through collaboration with citizen scientists, other research scientists in many disciplines, and data analysts that the next generation of researchers will bridge the gap between little bugs and big data.

Original languageEnglish
Pages (from-to)103-114
Number of pages12
JournalInsect Conservation and Diversity
Issue number2
Early online date4 Mar 2020
Publication statusFirst published - 4 Mar 2020

Bibliographical note

© 2020 The Royal Entomological Society


  • Citizen science
  • detection bias
  • global insect decline
  • insect conservation
  • monitoring
  • phenological shift
  • population trend
  • sampling bias
  • shifting baseline
  • time series


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