Insects worldwide are facing ‘death by a thousand cuts’

When we think about animals going extinct, we rarely think about insects. They seem to be everywhere, after all. Especially the ones we don’t like, be they flies or roaches. Yet a myriad of insect species are in deep trouble because of climate change and other environmental factors, according to a new study.

“Arthropods, invertebrates including insects that have external skeletons, are declining at an alarming rate. While the tropics harbor the majority of arthropod species, little is known about trends in their abundance,” write the authors, who compared the current biomass of arthropods in a national park in Puerto Rico’s Luquillo rainforest with data from the 1970s. They have found that arthropod biomass in the area has fallen by 10 to 60 times in just a few decades.

And along with the insects have gone many animals that feed on them. “Our analyses revealed synchronous declines in the lizards, frogs, and birds that eat arthropods. Over the past 30 years, forest temperatures have risen 2.0 °C, and our study indicates that climate warming is the driving force behind the collapse of the forest’s food web,” the scientists explain, noting that bugs cannot regulate their internal heat, which makes them vulnerable to long-term changes in temperature. “If supported by further research, the impact of climate change on tropical ecosystems may be much greater than currently anticipated,” they add.

Puerto Rico’s forests are hardly the only ones where insect populations have gone AWOL. In a recent study, a team of biologists said they had found that the number of invertebrates, including beetles, has decreased by 45% in just 35 years in Europe. Flying insects like bees have taken an especial turn for the worse in Germany and elsewhere.

The latest study has grave implications for the planet’s biosphere by indicating that far more species, large and small, may be at risk from climate change and other man-made causes than previously thought. The study, said David Wagner, an expert in invertebrate conservation at the University of Connecticut in the United States, “is a real wake-up call – a clarion call – that the phenomenon could be much, much bigger, and across many more ecosystems.”

David Wagner went on to call the study “one of the most disturbing articles I have ever read.”

The paper indicates that a food chain centered around arthropods in the local rainforest has suffered a catastrophic loss from the bottom up. “You have all these different taxa showing the same trends – the insectivorous birds, frogs and lizards – but you don’t see those among seed-feeding birds,” an American entomologist, Timothy Schowalter, commented.

Meanwhile, in areas dominated by agriculture insects have been battered by habitat loss and the use of pesticides and thus climate change alone can hardly be blamed for the drop in the numbers of insects in Europe and elsewhere. “The decline of insects in northern Europe precedes that of climate change there,” Wagner said. “Likewise, in New England, some tangible declines began in the 1950s.”

Insects, the expert adds, are facing “death by a thousand cuts” around the planet.