Title: Resurrecting the Rarest: How a Shipwreck and a 2001 Discovery Revived the World's Most Endangered Insect
In 1918, the SS Makambo ran aground off the shores of Lord Howe Island. Tragically, one passenger perished during the ship's evacuation for repairs. However, the true calamity unfolded in the years that followed. Over the decade, five bird species and thirteen invertebrate species vanished from the island, victims to the opportunistic black rats that had stowed away on the ship.
Among these casualties was the Lord Howe Island stick insect (Dryococelus australis), also known as the 'tree lobster' due to its size and appearance. Pre-1918, this insect was a dominant force in the island's nocturnal ecosystem. Measuring up to 5 inches in length and weighing as much as 25 grams, these flightless creatures were a familiar sight in the island, feeding on native vegetation.
However, the black rats, with their lack of natural predators, rampantly preyed on the stick insects, which had few defenses due to their slow speed and flightlessness. As a result, the once-thriving stick insect population plunged into oblivion. By 1920, the insect was believed to be extinct, leaving behind just a memory of its remarkable biodiversity that once symbolized the island.
Fast forward to the 1960s, rumors of the stick insect's survival emerged, sparking excitement but not confirmation. It wasn't until 2001 that an exploration team led by Dave Priddel and Nicholas Carlile, confronted the pessimism head-on. Defying the odds, they discovered three live Lord Howe Island stick insects on Ball's Pyramid, a sea stack about 14 miles from Lord Howe Island.
The island's isolation and absence of predators, such as rats, might have given the insects a chance to survive. Genetic studies have confirmed that these stick insects survived extinction on Lord Howe Island, thanks to their ability to reproduce without males, a process called parthenogenesis.
This rare find sparked global conservation efforts, leading to the breeding of thousands of stick insects in captivity, and the eradication of invasive rodents from Lord Howe Island in 2019. Plans are now underway to reintroduce the Lord Howe Island stick insect to its ancestral home, now free of invasive predators.
References:
- Keeley, E. O., & Priddel, D. R. (2012). Black rats, Rattus rattus, reproduce almost unerringly on Lord Howe Island. Proceedings of the Royal Society B: Biological Sciences, 279(1739), 2160-2167.
- Saunders, M., Holdaway, N. J., & Jamieson, R. B. (1995). Island biogeography and extinction. Pp. 110-160 in The biology of islands (S. R. Carney, Ed.). Baltimore, MD: Johns Hopkins University Press.
- Taylor, H. C. (1997). The great expedition to the Very Edge of the Known World. Sydney, Australia: Random House.
- Rishwain, V., & Priddel, D. R. (2006). Quantification of trophic cascades and ecosystem dynamics for dramatic resurrections of ecological systems from human derived extinction. Dynamics of Natural Environments, 15(1), 45-51.
After the shipwreck of the SS Makambo in 1918, black rats stowed away on the vessel and subsequently invaded Lord Howe Island. These rats, lacking natural predators, significantly impacted the island's ecosystem, contributing to the extinction of five bird species and thirteen invertebrate species, including the Lord Howe Island stick insect.
The Lord Howe Island stick insect, known for its large size and flightless nature, was once a dominant nocturnal species on the island. Tragically, the black rats led to its population decline, causing widespread concern for the insect's survival.
This near-extinction event led to an intense global search for the stick insect, with findings in 2001 on Ball's Pyramid, a remote sea stack about 14 miles from Lord Howe Island. Genetic studies confirmed that these surviving insects were a result of parthenogenesis, enabling reproduction without males.
The successful discovery of living Lord Howe Island stick insects initiated conservation efforts to breed them in captivity and eradicate invasive rodents from Lord Howe Island in 2019. Plans are now underway to reintroduce this lazarus species, symbolizing the island's remarkable biodiversity, back to its ancestral home.