Why insects are crucial to life on Earth – 08/30/2023 – Science

We live on a planet of insects. They make up about 70% of all known species on Earth and their combined biomass is 16 times that of humans.

300 million years ago, giant dragonflies with a wingspan of 75 centimeters flitted among tree ferns. These days, insects are extraordinarily diverse, with a huge variety of colors, shapes, and sizes.

They also play a crucial role in life on Earth. They serve as food for many animals, including most birds, bats, lizards, amphibians and freshwater fish.

About 80% of the world’s wild plant species also depend on insects to pollinate them, as do three-quarters of the plants we grow for food. It is no exaggeration to say that without insects many of us would starve to death.

But many types of insects in different parts of the world are endangered. While measuring insect populations is complex, there are worrying signs.

A major 2020 study estimated that land-dwelling insects are declining by about 9% per decade worldwide.

A German study found that the biomass of flying insects in nature reserves declined by an alarming 76% between 1989 and 2016. In the United States, monarch butterfly populations have declined by 80% this century.

Some species in the UK, such as the comma and spotted butterflies, are bucking the trend. But overall, the global geographical distribution of butterflies in the UK has declined by an average of 42% since 1976.

Invasive species are also suffering. Rats fed on the Saint Helena earwig, a type of centipede, until they drove the species to extinction and almost wiped out the New Zealand giant weta, a type of giant grasshopper.

Light pollution is also a problem, as it attracts moths and condemns them to death and disrupts the insect life cycle. It also disorients some beetles that navigate using the light of the Milky Way.

‘War against nature’

On top of all that, insects now have to deal with climate change. Some more adaptable insects, such as mosquitoes, cockroaches and houseflies, will benefit from warmer temperatures and more rain. But most will suffer.

Hornets are disappearing from their southernmost habitats, overheating on their furry bodies as the climate warms. Droughts, floods and forest fires can also devastate already threatened populations.

In 1962, American biologist Rachel Carson published the book “Silent Spring” (Silent Spring, in literal translation into Portuguese), warning that we were causing terrible damage to our planet.

She wrote: “Man is part of nature” and his war against nature “is inevitably a war against himself”.

But Carson’s prediction was just the beginning. Since then, insect-rich wildlife habitats have been destroyed on a massive scale. Soils were degraded and rivers clogged with silt, polluted or drained.

Agriculture, so dependent on insects for pollination, is responsible for much of its decline. It is estimated that 4 million tons of pesticides are released into the environment every year.

So what can we do if we want to protect our insects?

The simplest answer is to restructure gardens and porches, planting wildflowers and native shrubs, reducing mowing and finding alternatives to pesticides.

But individual actions will not be enough. Imagine green cities filled with trees, gardens and lakes, all free of pesticides and full of life. The movement towards sustainable agriculture for insects and all of nature is growing, but it needs much more support from both governments and consumers.

It’s still not too late. Most endangered insect species are not yet extinct and can recover quickly if protected.

The American biologist Paul Ehrlich compared the loss of species to the random detachment of rivets from the wing of an airplane. Remove one or two and the plane will probably be fine. Remove ten, 20 or 50 and at some point, catastrophic failure will occur and the plane will fall out of the sky.

Insects are the rivets that keep the planet running. How many can be safely removed from the plane before it crashes?