Editor's note: This blog was first published on February 18, 2019.
You might think insects are one of the things you wouldn’t miss too much if they suddenly disappeared. A recent paper, though, says you’d be wrong.
Scientists say that we’re losing insects at an unprecedented rate; 40% of the world’s insect species are declining, some up to eight times faster than birds, reptiles, and mammals. A third of insect species are now classified as “endangered.” Unfortunately, it’s the ones we humans tend to find useful—ants and bees, for example—that are disappearing, and their decline is making way for the ones we find less amenable—cockroaches and flies—to flourish.
The dwindling number of insects has implications that might not be immediately obvious, including some for the health of the soil. The paper, published in the journal Biological Conservation, reviews research from different parts of the world published during the last 13 years; it reports on the wide-ranging insect losses as well as some of the possible causes, which include habitat loss, in part due to intensive agriculture; use of synthetic pesticides and fertilizers; pathogens and invasive species; and climate change. Rising temperatures, the authors note, affect mainly the species in tropical regions far more than in colder areas.
We know that bees help in the pollination of many plant species, and most of us are aware of the decline in bee populations in recent years. Less widely recognized are the “environmental services” that other insects perform, such as breaking down and recycling waste products. They’re also near the bottom of the food chain, and as they die off, many other species that rely on insects as a main food source—birds, fish, and reptiles—might decline as well.
In this article summarizing the research, Dave Goulson of the University of Sussex notes, “Fast-breeding pest insects will probably thrive because of the warmer conditions, because many of their natural enemies, which breed more slowly, will disappear…. It’s quite plausible that we might end up with plagues of small numbers of pest insects, but we will lose all the wonderful ones that we want, like bees and hoverflies and butterflies and dung beetles that do a great job of disposing of animal waste.”