EXPERT REACTION: Has there been a global insect apocalypse?

Several studies over recent years have documented declines in insect abundance, biomass, distribution and diversity.  The best evidence comes from Europe and North America, areas that combine high human population density and widespread agriculture with the scientific infrastructure to sustain detailed insect abundance studies over decades. Evidence from other parts of the world, including Australia, is limited, at best.

The most likely common explanation for insect declines is the range of effects that agricultural intensification has in simplifying landscapes and ecosystems. It would be sensible to conclude that Australian insects are not immune to these effects, including land clearing, increased fertilizer and insecticide application, and the gradual removal of non-crop areas in these landscapes. About 75% of Australian arable land has been either cleared of native vegetation or disturbed and modified. 

Australian insect declines are likely occurring in the areas of the country that have experienced the greatest agricultural intensification, areas such as the Murray-Darling Basin,  the wheat belt of southern Australia, and the peri-urban areas around our major cities.

The magnitude, rate and geographic extent of the declines are not well understood.  There is evidence of a number of species in decline over relatively small spatial scales during the last 40 years.  Climate change often acts through intermediary drivers like fire to impact insect populations negatively.  Insects restricted to cooler areas at the summits of mountains in eastern Australia are likely to suffer population declines and possibly extinction as the weather warms and their habitats shrink as they move higher in altitude.

For Aotearoa New Zealand, the most important message is that we need to invest in assessing and monitoring our precious insect communities, because we simply don't know if most of our native insects are in decline as in other parts of the world. One positive note is that there are now more people taking notice of our extraordinary insects, and this might lead to a greater appreciation of their inherent value, and greater conservation effort. I think it is an exciting time for those of us who love insects. From kids adding pictures of their backyard insects to iNaturalist to those working to protect our iconic insect fauna and their habitats, everyone can make a difference.

Insects are hugely important to ecological processes that humans rely on, including the provision of food and recycling of nutrients into the soil. That is why they have been described as the little things that run the world. These latest studies confirm that serious declines in insect diversity and abundance are happening in a number of well-studied locations around the world, including some agricultural landscapes and alpine areas affected by climate warming.

They also show that insect declines are not universal, with losses not apparent for some other regions. The studies add significant urgency to the case that we need to develop agricultural practices that support healthy and diverse insect populations. We can learn from those places that are not witnessing dramatic insect declines. Globally we are not monitoring insect populations in a widespread or systematic way, which limits our power to respond. For this reason, it is very difficult to know if Australian insect populations are among those in decline, and it would pay to monitor trends especially in agricultural areas and at high elevations.

Insects are like the canaries once used to warn miners of the presence of toxic gases and the urgent need to flee to safety.  The demise of insects alerts us to our abuse of this planet through habitat destruction, climate change and excessive use of pesticides.  My own research has caused me to be concerned about insecticide use and the way in which it may synergize with these other stressors, particularly climate change, to harm beneficial insects. Agricultural productivity and ecosystem health are both absolutely dependent on insects.  Like the miners of old, we need to heed the warning.  Unlike the miners of old, we cannot afford to let the ‘canaries’ die.
 
Two world clocks are ticking. With every passing minute the global human population is increasing, while the available land useful for agriculture is decreasing.  We need to intensively research how human activity is impacting insects and find sustainable ways to produce our food.