Vanishing act in Europe and North America

What we know, and don’t know

Preliminary research in Europe and, to a lesser extent, in North America points to a decline in the abundance of numerous insect species, seemingly across families and habitats. And what we know from Europe is that overall abundance, at least in countries like Germany and the Netherlands, has plunged precipitously in just a few decades — even in nature reserves.

“I think this [serious loss] fits into all the other alarm bells that have been ringing for us and society lately,” Trautwein says. “The potential drivers of [the insect decline] are things that are causing major issues for society and for ecosystems more generally: climate change, habitat destruction, pesticide usage … This is all added evidence that we need to start taking this [mass extinction crisis] seriously.”

Indeed, because everything in the web of life is connected, and because the slashing of one thread leads to the weakening of the whole, crashing insect abundance is almost certainly linked to other ecological degradations occurring on our planet.

“All of a sudden you start looking at nature in a different way because the things that have been changing could very well be changing as a result of this insect decline,” says de Kroon. For example, insect decline may also explain losses among insect-eating birds, lizards and amphibians.

In the end, we are left with far more answers than questions. For example, how are insects faring on the rest of the planet, where research dollars are spread much more thinly, especially in the tropics of Africa, Asia and Latin America? It’s here that insect diversity stands unparalleled, with most species still unknown to science. But, to date, we have only a single major tropical study on just one protected area on a solitary island in the Caribbean, though we may soon have more.

“Things are in much, much more dire straits than I ever thought. I think the time has come to start using stronger terms,” concludes Lister. “When I saw [the headline] ‘Insect Apocalypse is Here’ [in the New York Times]… I thought, ‘Oh, my God, this isn’t good.’ You know how scientists don’t want to oversell or [use] hyperbole? But now, yes, that’s a good term — a catastrophic collapse is what I’ve been saying lately.”

Citations:

Koltz, A. M., Schmidt, N. M., & Høye, T. T. (2018). Differential arthropod responses to warming are altering the structure of Arctic communities. Royal Society Open Science, 5(4), 171503. doi:10.1098/rsos.171503

Loboda, S., Savage, J., Buddle, C. M., Schmidt, N. M., & Høye, T. T. (2017). Declining diversity and abundance of High Arctic fly assemblages over two decades of rapid climate warming. Ecography,41(2), 265-277. doi:10.1111/ecog.02747

Bowden, J. J., Hansen, O. L., Olsen, K., Schmidt, N. M., & Høye, T. T. (2018). Drivers of inter-annual variation and long-term change in High-Arctic spider species abundances. Polar Biology,41(8), 1635-1649. doi:10.1007/s00300-018-2351-0

Høye, T. T., Post, E., Schmidt, N. M., Trøjelsgaard, K., & Forchhammer, M. C. (2013). Shorter flowering seasons and declining abundance of flower visitors in a warmer Arctic. Nature Climate Change, 3(8), 759-763. doi:10.1038/nclimate1909

Ollerton, J., Winfree, R., & Tarrant, S. (2011). How many flowering plants are pollinated by animals? Oikos, 120(3), 321-326. doi:10.1111/j.1600-0706.2010.18644.x

Bar-On, Y. M., Phillips, R., & Milo, R. (2018). The biomass distribution on Earth. Proceedings of the National Academy of Sciences, 115(25), 6506-6511. doi:10.1073/pnas.1711842115

Komonen, A., Halme, P., & Kotiaho, J. S. (2019). Alarmist by bad design: Strongly popularized unsubstantiated claims undermine credibility of conservation science. Rethinking Ecology, 4, 17-19. doi:10.3897/rethinkingecology.4.34440

Wagner, D. L. (2019). Global insect decline: Comments on Sánchez-Bayo and Wyckhuys (2019). Biological Conservation, 233, 332-333. doi:10.1016/j.biocon.2019.03.005

Cardoso, P., Branco, V. V., Chichorro, F., Fukushima, C. S., & Macías-Hernández, N. (2019). Can we really predict a catastrophic worldwide decline of entomofauna and its drivers? Global Ecology and Conservation, 20. doi:10.1016/j.gecco.2019.e00621

Banner image of a pair of marsh tiger hoverflies (Helophilus hybridus) in Sweden by Axel Ssymank.

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Article published by Glenn Scherer

This story first appeared on Mongabay

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