Rats to riches: World's rarest insect stages a comeback
The SS Makambo ship incident in 1918 led to an unforeseen ecological disaster. Rats that escaped from the ship's deck onto Lord Howe Island quickly dominated the local environment, wiping out species that lacked natural predators. Among their victims was the stick insect Dryococelus australis, also known as the Lord Howe Island stick insect.
For decades, the stick insect was believed to become extinct around 1920. It wasn’t until 2001, during an expedition to Ball’s Pyramid—a rocky outcrop located in the Tasman Sea and far from Lord Howe Island—that scientists Dr. David Priddel and Dr. Nicholas Carlile discovered a small population of this species. It turned out that the insects had survived under extreme conditions. They benefited from protection from rats due to their presence on a rock remote from the island and the females' ability to reproduce without males (parthenogenesis), reported Earth Service.
The world's rarest insect returns
In 2003, two stick insects from the Dryococelus australis species, named Adam and Eve, arrived at the Melbourne Zoo to start a breeding program. Initially, there were some difficulties, but soon they successfully bred them, sending the insects to other zoos worldwide. Their return to Lord Howe Island was also planned, but eliminating the rats and mice on the island was crucial for the success of this project.
Rodents reached the island after the SS Makambo ran aground in June 1918 near Neds Beach, at the island's northern tip. The ship was relaunched after 9 days. During this time, the rats escaped from the deck and went to the land. Black rats, a species found on all continents except Antarctica, quickly overtook the island and dramatically affected its ecosystem. Their victims included numerous bird and insect species, including the aforementioned Dryococelus australis, now considered the world's rarest insect.
Only through a comprehensive deratization campaign in 2019 was the island freed from these pests. However, as noted by the Earth service, there were a few cases of their presence in 2021, requiring additional measures. Today, thousands of Lord Howe Island stick insects are bred in captivity, ready to return to their original homeland. Biologists emphasize that restoring this species is an ecological success and highlights the importance of protecting fragile ecosystems from invasive species.
