Large ‘extinct’ Australian cockroach has reappeared after more than 80 years: ScienceAlert

In 1887, scientists from the Australian Museum embarked on a pioneering expedition to Lord Howe Island, a small patch of land off the east coast of Australia. Among their many discoveries, they recorded “a large Blatta” – a kind of cockroach – under a rotting log.

It was later described as Panesthia latathe wood-eating cockroach of Lord Howe Island. P.lata was noted to be very abundant, playing a key role in nutrient recycling and presumably a food source for the many birds on the island.

Alas, in 1918, rats arrived on the island after a shipwreck. Towards the end of the 20th century, P.lata could not be found despite extensive searches over several decades and it was assumed to have become extinct due to rat predation.

But could he have survived in some unexplored pocket of the island?

Put the cockroach in its place

In 2019, the New South Wales Department of Planning and Environment (NSW DPE) implemented the final stage of their highly successful (if at times controversial) rat eradication program on the island.

Following this, I and my colleagues from NSW DPE, the Lord Howe Island Museum, the Chau Chak Wing Museum, the Australian National Insect Collection at CSIRO and the University of Melbourne became interested in the biology of P.lata and the possibility of repopulating the island with this insect.

This was expected because, in 2001, P.lata had been discovered on Blackburn and Roach Islands, two small islands close to Lord Howe Island.

But wait a minute: Why would we want to put cockroaches, one of the most reviled creatures on Earth, back on a beautiful island after their seemingly coincidental extermination?

Good, P.lata is, believe it or not, quite cute and charismatic, and has no interest in entering people’s homes. It is wingless, about 4 centimeters (1.6 inches) long, and remains hidden in the forest, where it burrows into the ground and feeds on fallen leaves and rotting wood at night.

fortuitous rocks

In July, we received funding from the Australia Pacific Science Foundation to study the genetics and ecology of P.lata of Blackburn and Roach Islands. So Maxim Adams, an honors student in our lab at the University of Sydney, and Nicholas Carlile from NSW DPE traveled to Lord Howe Island to begin the study.

Bad weather prevented them from traveling to Blackburn Island, so they decided to examine potential sites on Lord Howe Island which may have once been teeming with P.lata before the rats arrive.

They headed to an isolated area in the north of the island and decided to turn over some rocks. Literally the first rock they checked revealed a small congregation of cockroaches! I was supposed to join them three days later, but they called me this afternoon with great excitement to tell me the news.

They found a few more a few meters below the same fig tree, but extensive searches over the next few days turned up none in other nearby areas or other parts of the island.

Not the same as their neighbors

We did some preliminary DNA testing on our return to Sydney, finding the rediscovered cockroach population on Lord Howe Island to be distinct from those found on Blackburn and Roach Islands.

It is possible that the population got hooked due to rodent baiting in the area. Baiting has been done over the past decades to aid in the survival of various other endangered species.

We are currently conducting more extensive DNA studies, including historical museum samples collected in the late 19th and early 20th centuries, and samples from Ball’s Pyramid, about 20 kilometers (12 miles) to the southeast. from Lord Howe Island, collected by Dick Smith in the 1960s.

Through these studies, we hope to determine the relationship of the rediscovered population to those originally collected on the island a century or more ago and those from the outer islands. We also hope to uncover the origins and evolutionary history of P.lata.

The Lord Howe Group of Islands is a UNESCO World Heritage Site of global natural significance and is home to over 100 plant species found nowhere else on Earth, and many other endemic animal species. The biology of many of these species, especially the island’s invertebrates, remains mysterious.

We hope that our use of DNA techniques will help us establish P.lata as a model for understanding several million years of evolution on the Lord Howe Island archipelago, and aiding in the re-establishment of this shy but charismatic creature on its homeland.

Nathan Lo, Associate Professor, School of Biological Sciences, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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