Use of Pathogens for Eradication of Exotic Lepidopteran Pests in New Zealand

Abstract

New Zealand has a history of invasive pests causing significant damage both economically and environmentally. As an island nation with an agriculturally-based economy, preventing invasion by arthropods and other pests has a high priority. Discovery of three lymantriid moth species in the North Island of New Zealand resulted in eradication programmes, based on the use of the Bacillus thuringiensis kurstaki-based product, Foray 48B. New Zealand has no lymantriids and early evaluations of risk determined that each introduced species had the potential to cause economic loss and environmental damage. Populations of two of these pests, Orgyia thyellina (white spotted tussock moth) and Teia anartoides (painted apple moth), were first found in Auckland in 1996 and 1999, respectively, while a single Lymantria sp. male was trapped in Hamilton, 70 km to the south of Auckland, in 2003. This single male was originally identified as the Asian strain of L. dispar and a tentative morphological identification suggested it conformed to L. dispar praetera, a subspecies subsequently synonomised with L. umbrosa. However, molecular comparisons need to be completed to confirm specific identity and most publications in New Zealand still refer to the Asian gypsy moth in Hamilton. L. dispar had been frequently found on cargo and ships in New Zealand ports prior to the single male trap catch. Extensive spraying, both aerial and ground-based, led to the eradication of O. thyellina and T. anartoides from Auckland. The single gypsy moth find in Hamilton led to a limited aerial spraying of Foray 48B. No populations of gypsy moth were ever found. The successful eradication of the three lymantriid populations from New Zealand demonstrates that with sufficient treatment, eradication using a microbial-based insecticide is possible, even in urban environments.