News

Insect Decline: A Global Database Analyzed in Detail Highlights the Urgent Need to Revise Peer Review Processes in Scientific Journals

[] - Published on in the Press Room

In the face of the ecological crisis, databases are proliferating to track biodiversity trends, but they are not subject to systematic evaluation. Laurence Gaume of the Amap laboratory (UM, CNRS) and Marion Desquilbet (TSE, INRAE) examined InsectChange, published in Ecology, which compiles time series of insect abundance and biomass on a global scale. Their comprehensive analysis highlights more than 500 errors that call into question the results obtained from this database, particularly those of the meta-analysis published in *Science* in 2020. It also provides essential insights for improving InsectChange. Their study, recommended by the Peer Community in Ecology and published in the Peer Community Journal on October 8, 2024, highlights the issue of quality in large databases. While suggesting methodological approaches, it calls on scientific journals to implement safeguards against these detrimental effects on science and knowledge.

A lycaenid butterfly, a member of the Lycaenidae family, on a Nepenthes flower bud in northern Borneo. © Michaël Guéroult/INRAE.

The decline in insect populations raises major environmental, economic, and societal challenges. A new scientific paper just published in Peer Community Journal identifies more than 500 issues in the global temporal insect database InsectChange, which was published in *Ecology* in 2021.

This database was based on a meta-analysis published in *Science* in 2020, which concluded that the decline in insect populations was not as severe as previously thought and that agriculture was not one of the causes of this decline. Despite international criticism from 65 scientists, only a brief errata was published, leaving the results of this meta-analysis unchanged and widely publicized, and conveying a reassuring message to the general public.

This publication by Laurence Gaume and Marion Desquilbet highlights a multitude of new problems and analyzes their origin and nature (erroneous counts transferred from one database to another, sampling bias, non-standardized units of measurement, data from experiments, geographic coordinates of sampling sites that are inadequate for measuring the impact of agriculture or urbanization using satellite land-cover data, etc.). She concludes that these 553 issues—categorized as errors, inconsistencies, methodological problems, and information gaps—call into question any insect trends estimated using InsectChange and make it impossible to use this database to test whether land use is likely to explain the observed trends.

For example, many datasets on freshwater habitats actually include all aquatic invertebrates, and so-called “insect” increases turn out to be outbreaks of invasive mussels. By correcting these data, the two scientists found that the trends in freshwater insects published in *Science* had been greatly overestimated. Another type of problem is that half of the InsectChange datasets are not representative of insect dynamics under natural conditions. This is the case with dragonflies colonizing experimental ponds created by a British scientist to study them. These data are included without any mention of the experimental context, artificially leading to an increase in the number of these insects. Furthermore, the transformation of this non-standardized data, as performed in the meta-analysis, compromises the comparison of time-series slopes and the estimation of overall insect trends. Finally, the coverage of agricultural land around the sampling areas is greatly overestimated, partly due to inaccurate geographic coordinates in two-thirds of the datasets, which leads to the exclusion of croplands as a possible cause of insect decline.

The Need for a Systematic Evaluation of Baseline Data in Ecology

This observation raises a number of issues:

  • It is essential to ensure the quality of global ecological databases, which are proliferating amid the decline in biodiversity. In particular, this publication provides detailed and crucial information for improving InsectChange and enabling its informed use.
  • This publication outlines a reproducible analytical method that can serve as a basis for developing systematic evaluation frameworks for database quality.
  • She calls on scientific journals to improve the peer-review process prior to publication and to take post-publication comments into account, particularly for publications based on large datasets, and especially for prestigious journals, which serve as the primary sources for journalists.
  • Finally, it highlights the important role played by the nonprofit organization Peer Community In, particularly its commitment to open science and independent, transparent evaluation, which helps preserve scientific integrity and the quality of science.

References related to the article: