Volume 13, Issue 2 p. 103-114
Special Issue Article

Interpreting insect declines: seven challenges and a way forward

Raphael K. Didham

Corresponding Author

Raphael K. Didham

School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia

CSIRO Health & Biosecurity, Centre for Environment and Life Sciences, Floreat, WA, Australia

Correspondence: Raphael K. Didham, School of Biological Sciences, The University of Western Australia, Crawley WA, Australia. E-mail: [email protected]Search for more papers by this author
Yves Basset

Yves Basset

Smithsonian Tropical Research Institute, Balboa, Panama

Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic

Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic

Maestria de Entomologia, Universidad de Panamá, Panama City, Panama

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C. Matilda Collins

C. Matilda Collins

Centre for Environmental Policy, Imperial College London, London, UK

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Simon R. Leather

Simon R. Leather

Department of Crop & Environment Sciences, Harper Adams University, Edgmond Newport, Shropshire, UK

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Nick A. Littlewood

Nick A. Littlewood

Department of Rural Land Use, SRUC, Bucksburn, Aberdeen, UK

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Myles H. M. Menz

Myles H. M. Menz

School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia

Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany

Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany

Department of Biology, University of Konstanz, Konstanz, Germany

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Jörg Müller

Jörg Müller

Field Station Fabrikschleichach, Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Rauhenebrach, Germany

Bavarian Forest National Park, Grafenau, Germany

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Laurence Packer

Laurence Packer

Department of Biology, York University, ON, Canada

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Manu E. Saunders

Manu E. Saunders

School of Environmental & Rural Science, University of New England, Armidale, NSW, Australia

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Karsten Schönrogge

Karsten Schönrogge

UK Centre for Ecology & Hydrology, Wallingford, UK

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Alan J. A. Stewart

Alan J. A. Stewart

School of Life Sciences, University of Sussex, Falmer, Brighton, UK

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Stephen P. Yanoviak

Stephen P. Yanoviak

Smithsonian Tropical Research Institute, Balboa, Panama

Department of Biology, University of Louisville, Louisville, KY, USA

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Christopher Hassall

Christopher Hassall

Faculty of Biological Sciences, University of Leeds, School of Biology, Leeds, UK

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First published: 04 March 2020
Citations: 196
Editor: Jemina Wood

Abstract

  1. 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.
  2. 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.
  3. 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.
  4. 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.

Conflict of Interest

The authors declare no conflict of interest.