Insect Apocalypse
Insects are facing mass extinction — and if they die out, so will we.
It is difficult to say exactly how many insect species there are out there. Current estimates lie around 5.5 million species, of which only a fifth have been named. This lack of description makes it difficult to estimate how many insect species are in danger of extinction or which have already become extinct. The International Union for Conservation of Nature (IUCN) publishes a red list of endangered species, and the latest version lists 8,400 insect species as endangered out of the roughly one million species that are described. It is reasonable to assume that at least a similar fraction of all insect species is similarly threatened; most likely more, given that the undescribed species tend to be rarer than the described ones.
In February 2020, a group of 25 international entomologists published an article in the peer-reviewed journal Biological Conservation, warning of the dire situation for insects in the world. They have used comparisons with land snail populations to estimate that between 5 percent and 10 percent of insect species have died out since the beginning of the industrial era, and they estimate that another 10 percent or so may go extinct in the coming decades.
With so many insect species, why should we worry that a tenth of them are heading for extinction? It’s not like there won’t be millions of species left. Well, there are several reasons why we should worry. One is that insects tend to be highly specialised, and if a species dies out, there may not be another that can fill the exact same niche in the global ecosystem. Secondly, and more importantly, the extinction of insect species is an indicator of the massive damage that is being done to the ecosystem. Insects die out because of climate change, pollution, loss of habitat, invasive species, overexploitation of resources, loss of biodiversity, and a host of other causes that hurt not just insects, but all parts of the ecosystem. Of greatest importance to us is that insects are vital for plant pollination. Without pollinating insects, we could not grow very many of the crops we rely on for food, and we are already witnessing alarming declines in populations of insects that are important for crop pollination, including honeybees, bumblebees, and butterflies. The overall biomass of flying insects — our main pollinators — has decreased by more three quarters in less than thirty years. Preserving insect diversity and protecting insect populations may hence become a question of the survival of humanity — or at least most of us.
Habitat loss may be the greatest driver of insect extinction. Wild forests are cut down and replaced with farmland or plantations with a fraction of the biodiversity, rivers are regulated or dammed or choked in silt from agricultural runoff, ponds are drained to make room for farmland or urban developments, and mining destroys subterranean insect habitats. Pollution and fertiliser use are also important destructive factors. With habitat loss also comes habitat fragmentation, where populations of insect and other animals may find it difficult to reach suitable nearby habitats. This may make it impossible for insect species to migrate to new habitats as climate change make their current habitats unsuitable for them.
While the forecasts of insect decline are dire, an insect apocalypse is not an inescapable event. There are things we can do to prevent or at least mitigate the disater, as the authors of the above-mentioned article write in a companion article also published in Biological Conservation.
As a first step, we should learn to appreciate insects more. This does not just mean appreciating the beauty of a butterfly, the activity of an ant, or the bustle of a beehive. We should become more aware of the important parts insects play in our global ecosystem, and we should view the possible extinction of an insect species with the same urgency as the extinction of a species of mammal, bird, or reptile. Even humble, drab, crawling insects may be more important than we realise.
Second, we should take care to preserve and restore insect habitats and their biodiversity. On a larger scale, we should stop the deforestation that every year clears forest areas the size of the United Kingdom as well as the regulation and draining of wetlands. On a smaller scale, we can preserve roadside ditches and strips, refrain from mowing all our lawns, establish insect shelters in our gardens by e.g. leaving dead wood, and engaging in a little ‘guerrilla gardening’. Farmers and gardeners alike should stop using pesticides that endanger insects, even at the cost of limited short-term insect damage to crops and flowers (or use non-toxic pest control). Adding biodiversity to grazing fields rather than just sowing grass also helps, and livestock grazing can benefit wild forests and grasslands. Forests should not always be cleared of deadwood, and occasional, limited forest fires may also help. Preserving freshwater systems and adding vegetation heterogeneity to them are also important steps, even on small scales such as ponds in gardens and parks and on golf courses.
Organic farming or other types of farming that minimize chemical pest control are an important part of the puzzle. Leaving small, wild hillocks or ponds in fields rather than levelling them adds a lot to biodiversity of both vegetation and insects at a very low cost for farmers. The old traditional of planting trees as windbreaks between fields should be maintained or reintroduced. Walls of rough stone and fences of untreated wood that provide homes for insects are better than brick walls or treated wooden fences. Urban green areas are also beneficial for insects; even little things like letting railway clearings grow wild, planting trees and flowerpots in streets, and establishing living, green roofs on bus shelters and public buildings. Nor should we forget to fight pollution of earth, water, and air and strive to limit climate change.
On a final note, preserving insects is not just worthy as a means of survival of the human race. Every step to protect insect populations and diversity also helps make the world greener and more beautiful, with more diversity to astonish us and our children. Such beauty and wonder do not count towards GDP, but does that make them any less important?
