Considered extinct for 80 years – Scientists rediscover a unique insect

Lord Howe Island wood-feeding cockroach (Panestia lata). Credit: Justin Gilligan/NSW DPE

Long thought to be extinct on the main island of Lord Howe Island, the wood-eating cockroach was found at the base of a Banyan tree.

A University of Sydney biology student has discovered a large, wingless, wood-eating cockroach that was thought to be extinct since the 1930s and is unique to Lord Howe Island in Australia.

“For the first 10 seconds or so, I thought, ‘No, it can’t be,'” said Maxim Adams, an honors student under Professor Nathan Law at the University of Sydney’s Faculty of Biological Sciences. “I mean, I picked up the first stone under that huge banyan tree and there it is.”

“We found families of them, all under this one banyan tree,” said senior scientist Nicholas Carlisle of the NSW Department of Planning and Environment (DPE), who was with Adams exploring North Bay, a secluded white sand beach accessible only by foot or water . “Actually, Maxim and Nathan were there the rest of the week, looked under every other banyan tree in North Bay, but found nothing.”

Maxim Adams under the banyan tree

University of Sydney graduate student Maxim Adams under the banana tree where they made the surprising discovery. Credit: Nicholas Carlisle/NSW DPE

The rare Lord Howe Island wood-eating cockroach (Panestia lata), which was once common throughout the archipelago, was thought to be extinct when the rats arrived on the island in 1918. Over the next few decades, searches revealed scattered populations of close relatives on two small offshore islands. However, the rediscovered group is genetically distinct from them.

“The survival is great news as it has been more than 80 years since it was last seen,” Lord Howe Island board chairman Atticus Fleming said of the find, first made in July 2022. “Lord Howe Island it is truly a spectacular place, it is older than the Galapagos Islands and is home to 1,600 native species of invertebrates, half of which are found nowhere else in the world.

“These cockroaches are almost like our own version of Darwin’s finches, separated into small islands over thousands or millions of years, developing their own unique genetics,” he added.

Maxim Adams holds a Lord Howe Island wood cockroach feeding a cockroach

University of Sydney graduate student Maxim Adams, who keeps one of Lord Howe Island’s wood-eating cockroaches, discovered (Panestia lata). Credit: Justin Gilligan/NSW DPE

Although they may not be cute and fluffy, cockroaches play a crucial role in the island’s ecosystem by recycling nutrients, speeding up the decomposition of logs and serving as a food source for other animals. For this reason, experts are investigating the viability of reintroducing them from offshore islands to the main island. Now they don’t have to.

“There is still so much to learn,” said Professor Lo, head of the Laboratory of Molecular Ecology, Evolution and Phylogenetics (MEEP) in the School of Life and Environmental Sciences. “We hope to study their habitat, behavior and genetics and learn more about how they managed to survive through further experiments on the island.”

The wingless cockroach is 22-40 mm long, with a metallic body color that ranges from reddish to black. Australia is host to 11 species of Panesthia wood cockroaches, powerful burrowers that live inside and feed on rotting logs in the rainforests and open forests of coastal northern and eastern Australia.

Scientists under a banyan tree

University of Sydney graduate student Maxim Adams (left) and NSW Department of Planning and Environment scientist Nicholas Carlisle (right) under the banyan tree where they made the surprising discovery. Credit: Justin Gilligan/NSW DPE

They carry specialized microorganisms in their guts that help digest the cellulose in the wood. Females give birth to nymphs that stay in family groups with the adults. But unique arthropods behave differently and may have been misnamed.

“Despite their common name, which suggests they are wood-eating cockroaches that burrow into rotting logs, we now believe they are more of a ‘rock cockroach’, with rocks being an important component of their habitat, possibly due to their co-evolution with land foraging on Lord Howe Woodhen Island,” said DPE’s Carlisle, who was part of the team of scientists who rediscovered the stick insect on Lord Howe Island in 2001 at Ball’s Pyramid, a volcanic outcrop on 23 km off the coast of Lord Howe Island.

The University of Sydney led the research in partnership with the NSW Department of Planning and Environment and the Lord Howe Island Museum.

The research was funded by the Australia and Pacific Science Foundation and the Australian Research Council.

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