Fiji’s ants reveal new clues about global insect collapse

Insects are everywhere – flying, crawling, buzzing, and doing far more for the Earth than most of us realize. They help plants grow by spreading pollen, recycle dead material, and keep ecosystems running smoothly.

Recently, however, scientists have noticed something troubling: insect populations are declining. This trend could become a serious problem.

What remains unclear is whether this is a new phenomenon or part of a longer pattern. A recent study explored this question using a surprising tool: ants from museum collections.

Ants unlock insect history

To determine how insects have changed over time, scientists at the Okinawa Institute of Science and Technology (OIST) looked to ants that inhabit Fiji, a cluster of tropical islands in the South Pacific.

The islands are remote and host unique species found nowhere else, making them ideal for researching long-term patterns of insect populations.

Instead of merely counting ants in the field, the team used a technique called “community genomics.” They analyzed old ant specimens from museum collections and sequenced their DNA. Although DNA degrades over time, scientists can extract enough from small, damaged fragments to reveal important information.

The goal was to reconstruct the ants’ family trees and track their population sizes over hundreds to thousands of years.

Ant DNA reveals hidden insect decline

The results were troubling. Out of all the ant species that are native to Fiji, 79 percent are shrinking in population. These ant species have existed on the islands for thousands or even millions of years.

Yet in the last few centuries – particularly since European contact and the advent of world commerce -their populations have drastically declined.

Meanwhile, ant species that have been transported by humans, either intentionally or inadvertently, are flourishing. These newcomers are spreading fast and outcompeting the native ants. Many of the worst declines seem to have happened in just the last few hundred years.

Islands face decline first

Fiji isn’t just a pretty group of islands – it’s a warning sign. Islands tend to be hit harder and faster when environmental disasters strike.

They’re small, isolated, and their species often evolve in ways that make them more vulnerable. When something comes along – such as a predator, disease, or invasive species – it will produce an unbalancing effect on everything.

“Being closed, isolated ecosystems, islands are expected to feel the effects of human impact faster, so they are kind of a canary in the coal mine,” said Dr. Cong Liu, the study’s lead author.

Getting the data wasn’t easy. Fieldwork on tropical islands is tough, and long-term monitoring isn’t always possible. So instead, the researchers turned to decades’ worth of museum specimens – collected by their team and other scientists over many years.

Tracking the ant invasions

Using a method known as “museumomics,” the scientists sequenced thousands of ants from more than 100 different insect species. This analysis allowed them to identify 65 separate colonization events in Fiji.

Some species arrived naturally millions of years ago, while others were clearly introduced by humans more recently.

By comparing DNA from these samples, the team could determine which populations were growing and which were shrinking.

Native ants were declining. Invasive ants were on the rise. “Most recorded extinctions have historically been from island systems,” said Dr. Liu.

A global insect warning sign

This study wasn’t just about ants – or even just about Fiji. It’s about understanding what’s happening to insects worldwide, and using every tool available to figure that out.

“It can be difficult to estimate historical changes to insect populations, because with few exceptions, we haven’t been directly monitoring populations over time,” said Dr. Evan Economo, a senior author of the study.

The researchers used museum specimens to analyze multiple species’ genomes in parallel, revealing whether populations were growing or shrinking and enabling community-wide reconstructions.

Insects reveal hidden biodiversity

Conservation groups usually focus on big, charismatic animals like pandas, tigers, or elephants. But insects are just as important – and they’re harder to keep track of.

That’s why this research matters. It shows that museum collections, some more than a century old, can be turned into data gold mines.

“This study also highlights the importance of biodiversity and museum collections,” said Professor Alexander Mikheyev.

“As our scientific toolbox expands, we can capture more and more information from these collections, so it is essential that we continue investing in and maintaining these vital resources.”

Insects aren’t vanishing silently

The same research team is also studying insects in Okinawa, Japan. There, they’re using real-time monitoring like sound sensors and traps to learn more about how insect populations change day by day.

“Insects are essential for the environment,” said Economo. “As scientists, we need to play our part in their protection, and provide and analyze the relevant data to ensure the long-term integrity of our ecosystems.”

The crash in insect populations isn’t just a scary headline. It’s a real shift happening across the globe, often out of sight. By turning to ants – and the museums that stored them – the researchers have found one way to see what’s been happening all along.

The full study was published in the journal Science.

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