"The unnoticed apocalypse": insect declines and why they matter

"In early 2019, Australian entomologist Francisco Sanchez-Bayo published a scientific review of all existing evidence for insect declines [Sanchez-Bayo & Wyckhuys 2019]. He located 73 studies, mainly from Europe and North America, which collectively suggest that the rate of local extinction of insect species is eight times faster than that of vertebrates. He also estimated that, on average, insects are declining by 2.5% each year, with 41% of insect species threatened with extinction. The paper concludes: “we are witnessing the largest extinction event on Earth since the late Permian” (a geological epoch 250 million years ago)."  [Professor Dave Goulson, FRES, "Insect declines and why they matter", 2019]

This report originates in Britain but it is relevant to insect decline world-wide, including the Northern Rivers region of New South Wales.

The Wildlife Trusts (Somerset), Insect declinesand why they matter:

In the last fifty years, we have reduced the abundance of wildlife on Earth dramatically. Many species that were once common are now scarce. Much attention focusses on declines of large, charismatic animals, but recent evidence suggests that abundance of insects may have fallen by 50% or more since 1970. This is troubling, because insects are vitally important, as food, pollinators and recyclers amongst other things. Perhaps more frightening, most of us have not noticed that anything has changed. Even those of us who can remember the 1970s, and who are interested in nature, can’t accurately remember how many butterflies or bumblebees there were when we were children. 

The bulk of all animal life, whether measured by biomass, numerical abundance or numbers of species, is comprised of invertebrates such as insects, spiders, worms and so on. These innumerable little creatures are far more important for the functioning of ecosystems than the large animals that tend to attract most of our attention. Insects are food for numerous larger animals including birds, bats, reptiles, amphibians and fish, and they perform vital roles such as pollination of crops and wildflowers, pest control and nutrient recycling. 

There have been several recent scientific reports describing the rapid decline of insects at a global scale, and these should be a cause of the gravest concern (summarised in Sanchez-Bayo & Wyckhuys 2019). These studies suggest that, in some places, insects may be in a state of catastrophic population collapse. We do not know for sure whether similar reductions in overall insect abundance have happened in the UK. The best UK data are for butterflies and moths which are broadly in decline, particularly in farmland and in the south. UK bees and hoverflies have also shown marked range contractions. The causes of insect declines are much debated, but almost certainly include habitat loss, chronic exposure to mixtures of pesticides, and climate change. The consequences are clear; if insect declines are not halted, terrestrial and freshwater ecosystems will collapse, with profound consequences for human wellbeing. 

The good news is that it is not too late; few insects have gone extinct so far, and populations can rapidly recover. 

We urgently need to stop all routine and unnecessary use of pesticides and start to build a nature recovery network by creating more and better connected, insect friendly habitat in our gardens, towns, cities and countryside. 

Only by working together can we address the causes of insect decline, halt and reverse them, and secure a sustainable future for insect life and for ourselves. 

This report summarises some of the best available evidence of insect declines and proposes a comprehensive series of actions that can be taken at all levels of society to recover their diversity and abundance.

Read the full report here.