Re-introduction of the leaf-vein slug to Quail Island, Banks Peninsula, Canterbury, New Zealand

Summary

The leaf-vein slug (Pseudaneitea maculata), a nocturnal fungus-feeding species that helps clean sooty mould from leaves in New Zealand forests, was translocated from Orton Bradley Park to nearby Quail Island in Lyttelton Harbour by Lincoln University researchers as part of the island's broader ecological restoration, since its early-stage regenerating habitat lacked the mature trees and rotten logs slugs normally shelter in. Researchers developed artificial refuges, wooden discs cut from tree trunks and hollow weta-motel blocks with narrow mouse-proof entrances, that doubled as monitoring tools and, for the discs, as a food source by cultivating fungi beneath them. In 2004, 26 slugs plus 32 eggs laid in captivity were collected from source-site refuges, held briefly in a 12°C incubator with mould-infested leaves, then released under wooden discs arranged in a 6x6 grid with 5-meter spacing at a moist site among young native trees and flax. Because leaf-vein slugs are hermaphroditic, no pairing was required to establish breeding, simplifying collection and establishment. Monitoring in 2007, 2008 and 2009 found consistently good numbers of both slugs and eggs under the discs despite continued house mice on the island, protected partly by a trap grid installed around the release site. Major difficulties included initial uncertainty in species identification and the risk that disturbing the discs during inspection could break the soil seal protecting slugs from desiccation and predation. The project rates itself Successful, citing sustained slug and egg numbers three years post-release from a relatively small founding population.