Some scientists think insect populations are increasing.Here's why they're wrong

The debate over the misleading results of a flawed study raises questions about how biodiversity loss should be measured

- SOFIA QUAGLIA

Back in 2020, when French scientists, Drs Laurence Gaume and Marion Desquilbet, first heard the news about a new international insect decline database, they felt something was off. It suggested that some insect species were actually on the rise-a claim that contradicted years of research.

"We were concerned. We felt the conclusions were over-optimistic," says Desquilbet, an environmental economist at Toulouse School of Economics. "It went against prior results clearly pointing to a decline in insect biodiversity."

When I talk to them five years later, old concerns about mistakes in the insect database shine a light on new, big-picture qualms about how biodiversity is measured. But more than that, whether scientific discovery should be up for debate.

The database they were initially concerned with was called InsectChange and merged various other datasets created by researchers. In 2020, scientists from Germany, Russia and the US published an analysis of InsectChange, examining its data and findings.

The main takeaways were that while insects on land weren't doing well, declining at a rate of nine per cent per decade, freshwater insects were making a comeback - increasing at 11 per cent per decade. It made the picture of worldwide insect decline look much more nuanced than previously thought.