Declining abundance of beetles, moths and caddisflies in the Netherlands

By C. Hallmann, T. Zeegers, R. Klink, R. Vermeulen, P. Wielink, H. Spijkers, J. Deijk, W. Steenis, Eelke Jongejans. Insect Conservation and Diversity, 2019

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Recently, reports of insect declines prompted concerns with respect to the state of insects at a global level. Here, we present the results of longer‐term insect monitoring from two locations in the Netherlands: nature development area De Kaaistoep and nature reserves near Wijster. Based on data from insects attracted to light in De Kaaistoep, macro‐moths (macro‐Lepidoptera), beetles (Coleoptera), and caddisflies (Trichoptera) have declined in the mean number of individuals counted per evening over the period of 1997–2017, with annual rates of decline of 3.8, 5.0 and 9.2%, respectively. Other orders appeared stable [true bugs (Hemiptera: Heteroptera and Auchenorrhyncha) and mayflies (Ephemeroptera)] or had uncertainty in their trend estimate [lacewings (Neuroptera)]. Based on 48 pitfall traps near Wijster, ground beetles (Coleoptera: Carabidae) showed a mean annual decline of 4.3% in total numbers over the period of 1985–2016. Nonetheless, declines appeared stronger after 1995. For macro‐moths, the mean of the trends of individual species was comparable to the annual trend in total numbers. Trends of individual ground beetle species, however, suggest that abundant species performed worse than rare ones. When translated into biomass estimates, our calculations suggest a reduction in total biomass of approximately 61% for macro‐moths as a group and at least 42% for ground beetles, by extrapolation over a period of 27 years. Heavier ground beetles and macro‐moths did not decline more strongly than lighter species, suggesting that heavy species did not contribute disproportionately to biomass decline. Our results broadly echo recent reported trends in insect biomass in Germany and elsewhere.

Subfields: Ecological Modeling, Ecology, Evolution, Behavior and Systematics, Social Psychology

View Paper: https://www.semanticscholar.org/paper/8eef5d910490fa17eef8f34445740b7e04fd6b6d

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Citations in the corpus

Is the insect apocalypse upon us? How to find out (2020, background): “Declines are also reported from many western and northern European countries, representing a suite of different insect orders (e.g., Conrad et al., 2006, Shortall et al., 2009, Schuch et al., 2012; van Strien et al., 2019; Hallmann et al., 2019; Powney et al., 2019; see also reviews by Sánchez-Bayo ”
Is light pollution driving moth population declines? A review of causal mechanisms across the life cycle (2020, background): “In Great Britain, standardised monitoring has revealed that 34% of the 390 commonest macromoths had statistically significant declines between 1970 and 2016, with a 25% decline in a 442-species abundance indicator over the same period (Randle et al., 2019; Hayhow et al., 2019) and there is evidence ”
Further evidence for a global decline of the entomofauna (2020, background): “2013), as the population of a given species may decline while maintaining its distribution in a region or country, and (ii) biomass also underestimates abundance (Hallmann et al. 2020), probably because small‐bodied species outnumber large‐size, heavier ones and biomass thus imperfectly captures cha”