Rare Insect Makes Remarkable Comeback from Near-Extinction
Just 20 to 30 ‘tree lobsters’ are left in their natural habitat, and this vulnerable group was found again in 2001, 80 years after being thought extinct.
The wild Lord Howe Island stick insects (Dryococelus australis) currently cling to survival on Ball’s Pyramid, a nearly vertical volcanic outcrop.
San Diego Zoo now welcomes visitors to witness the remarkable Australian animals that defy extinction in person.
Ball’s Pyramid, prone to catastrophic weather events and landslides, is far from an ideal refuge for a critically endangered species.
In this habitat, the herbivorous stick insects rely solely on Melaleuca howeana, their only food plant. Unfortunately, these shrubs are threatened by an invasive vine, which cannot be fully removed as its roots help stabilize the cliffs.
Numerous zoos worldwide have collaborated to rescue these large, flightless phasmids from both metaphorical and literal cliff edges.
San Diego Zoo entomologist Paige Howorth emphasizes, “Bringing our guests close to this rare and iconic species is a great way to raise awareness for the lesser-known animals that run the world.” She further notes the vital role of invertebrates in sustaining life through processes like pollination, decomposition, predation, and serving as food for other animals.
The Lord Howe Island stick insects were once found clustering on the branches of Moreton Bay figs (Ficus macrophylla) and woolly tea trees (Leptospermum lanigerum) on their namesake island, situated off the east coast of Australia.
Shipwrecked Rodents Drive ‘Tree Lobsters’ to the Brink of Extinction
The chunky, hand-sized stick insect fell prey to the rat invasion of 1918, as shipwrecked rats feasted, multiplied, and continued to devour until not a single ‘tree lobster’ could be found.
The rats, in their voracious appetite, wiped out additional native species on the island, leading to the extinction of five birds, two plants, and 12 other invertebrates.
Declared extinct in 1986 after no sightings since 1920, the Lord Howe stick insect’s hidden refuge was revealed by rumors of insect poop and skin sheds discovered by climbers in the 1960s on a volcanic sea stack 23 kilometers away from the island.
The remarkable survival of the Lord Howe stick insect in such a desolate place, despite critically low numbers, is attributed to the female’s ability to clone themselves through parthenogenetic reproduction.
In 2003, despite initial hesitation due to the risk, a rescue team safely extracted four of the remaining black stick insects to initiate a breeding program, aiming to safeguard the population.
Melbourne, Bristol (now closed), and San Diego Zoos, working together, have successfully established a captive population of the Lord Howe stick insect, now numbering in the thousands.
Reviving Biodiversity
Since 2019, a significant initiative, aided by rat-detecting dogs, has been underway to eradicate rats on Lord Howe Island. This effort has led to a remarkable resurgence in the island’s unique wildlife, benefiting species from endangered land snails to the flightless Lord Howe Woodhen.
Lord Howe Island resident Hank Bower, speaking to The Sydney Morning Herald in 2022, describes the ongoing transformation as an “ecological renaissance.” He notes the discovery of new fruits, increased insect sightings reported to the Australian Museum, and a flourishing environment with blooming plants and a carpet of seedlings.
The zoos are optimistic that the thriving populations they’ve cultivated will be instrumental in reintroducing the insects to their island home once it’s deemed rat-free and safe for their return.
Nicholas Carlile, a NSW state government ecologist, highlights the crucial role of the Lord Howe stick insect in the island’s ecology as an ecosystem engineer, emphasizing their impact on nutrient cycling. He expresses hope for their return to the forest, describing them as a missing piece of the ecological puzzle.
Read the original article on: Science Alert
Read more: A Potential Solution for Treating Obesity Might be Found in the Shells of Crabs and Insects
