Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances

By Roel van Klink, D. Bowler, K. B. Gongalsky, A. Swengel, A. Gentile, Jonathan M. Chase. Science, 2020

953 citations recorded by the source corpus.

Local drivers of decline matter Recent studies have reported alarming declines in insect populations, but questions persist about the breadth and pattern of such declines. van Klink et al. compiled data from 166 long-term surveys across 1676 globally distributed sites and confirmed declines in terrestrial insects, albeit at lower rates than some other studies have reported (see the Perspective by Dornelas and Daskalova). However, they found that freshwater insect populations have increased overall, perhaps owing to clean water efforts and climate change. Patterns of variation suggest that local-scale drivers are likely responsible for many changes in population trends, providing hope for directed conservation actions. Science, this issue p. 417; see also p. 368 Global changes in insect populations reflect both decline and growth. 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.

Subfields: Ecological Modeling, Ecology, Nature and Landscape Conservation

View Paper: https://www.semanticscholar.org/paper/952275f9c2ba0080ef406eb0ca952133ef1f2521

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Citations in the corpus

Cascading extinctions as a hidden driver of insect decline (2020, background): “…Environmental Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, U.K. Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall TR10 9FE, U.K. E-mail: d.sanders@exeter.ac.uk in the included datasets when observing different taxa and locations (van Klink et al., 2020).”
Geographical, temporal and taxonomic biases in insect GBIF data on biodiversity and extinction (2021, background): “Another study further revealed that while terrestrial insect abundance is declining, it is increasing in freshwater species (Klink et al., 2020).”
Insect responses to global change offer signposts for biodiversity and conservation (2020, background): “Data gathered over the past half century do not indicate that insects are declining everywhere (van Klink et al., 2020), but do provide strong evidence of changes to insect abundance, distributions, and diversity that are consistent with widespread effects of land-use and climate change (Lenoir et…”