The Lord Howe Island wood-feeding cockroach (Panesthia lata), a species of large wingless cockroach that disappeared from its home island following the introduction of ship rats (Rattus rattus), has been rediscovered by biologists from the University of Sydney.
The Lord Howe Island wood-feeding cockroach (Panesthia lata). Image credit: Justin Gilligan / NSW Department of Planning and Environment.
The Lord Howe Island wood-feeding cockroach is 2.2-4 cm (0.9-1.6 inches) long, with a metallic body color that varies from reddish to black.
Once widespread, the species was thought to have become extinct following the arrival of rats on the island in 1918.
Over the next few decades, searches uncovered scattered populations of close relatives on two tiny islands offshore. But the group rediscovered is genetically different from those.
“The survival is great news, as it has been more than 80 years since it was last seen,” said Lord Howe Island Board Chair Atticus Fleming.
“Lord Howe Island really is a spectacular place, it’s older than the Galápagos islands and is home to 1,600 native invertebrate species, half of which are found nowhere else in the world.”
“These cockroaches are almost like our very own version of Darwin’s finches, separated on little islands over thousands or millions of years developing their own unique genetics.”
“For the first 10 seconds or so, I thought ‘No, it can’t be.’ I mean, I lifted the first rock under this huge banyan tree, and there it was,” said Maxim Adams, a student at the University of Sydney.
“We found families of them, all under this one banyan,” added Nicholas Carlile, a researcher with the NSW Department of Planning and Environment.
The Lord Howe Island wood-feeding cockroach are cornerstones of maintaining a healthy ecosystem on the island, acting as important nutrient recyclers, important in speeding the breakdown of logs and as a food source for other species.
Which is why the scientists had been exploring the feasibility of re-introducing them to the main island from offshore islets. Now they don’t have to.
“There is still so much to learn. We are hoping to study their habitat, behaviors, and genetics and learn more about how they managed to survive, through further experiments on the island,” said University of Sydney’s Professor Nathan Lo.
Lord Howe Island wood-feeding cockroaches carry specialized microorganisms in their guts that help digest the cellulose in the wood.
Females give birth to nymphs which stay in family groups with the adults. But the unique arthropods behave differently and may have been misnamed.
“Despite its common name suggesting they are wood-feeding cockroaches and that they burrow in rotting logs, we now believe they are more of a ‘rock-roach,’ with rocks forming an important component of their habitat, possibly due to their co-evolution alongside the ground foraging Lord Howe Island woodhen (Hypotaenidia sylvestris),” Carlile said.
