Farm Forestry New Zealand
PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Gypsy moth- a threat to New Zealand trees
Scion is the leading provider of forest-related knowledge in New Zealand
Formerly known as the Forest Research Institute, Scion has been a leader in research relating to forest health for over 50 years. The Rotorua-based Crown Research Institute continues to provide science that will protect all forests from damage caused by insect pests, pathogens and weeds. The information presented below arises from these research activities.
From Forest Health News 9, may 1992.
The gypsy moth, Lymantria dispar (L.) is one of the most serious defoliators of hardwoods in North America. It is a native of Europe and Asia and was introduced into the USA in 1869 when a French scientist brought some eggs from Europe for the purpose of crossing the species with silk worms. During the course of the work some of the larvae escaped and the species became'established. In the USA the gypsy moth is widespread in the eastern and central states and only sporadically occurs in the west. However in the summer of 1991 gypsy moths of Asian origin were found to be established at three localities in western North America, viz. Vancouver, British Columbia; Tacoma, Washington; Portland, Oregon. The Asian race (it is the same species) of the gypsy moth (AGM) differs from the European race in its ability to feed on a wider range of host plants (including conifers) and in the females being strong fliers. Females of the European race are unable to fly. It is difficult to distinguish the two races by their appearance.
In recent years ships entering these North American ports from the Far East of Russia have been found with gypsy moth egg masses on their superstructures. Apparently there is an outbreak of AGM in forests near several Russian ports and mated female moths are attracted to light and fly at night to illuminated ships and lay their eggs. Some ships had several thousand egg masses and on at least one in the port of Vancouver was observed with larvae hatching and dispersing in the spring of 1991. Canadian authorities have refused entry to ships on which egg masses have been found.
In the spring of 1992 both Canada and the USA are attempting to eradicate these three infestations using aerial applications of Bacillus thuringiensis. Agriculture Canada has treated over 16,000 hectares in the greater Vancouver area and the USDAhas budgeted $14.4 million to treat 54,000 hectares near Tacoma and 4,200 hectares around Portland. Most of the spraying is done using DC6 aircraft.
The question has been asked could the AGM reach New Zealand on ships from Russia? To get here the ships would have to pass through the tropics and the eggs should hatch and the larvae starve to death before the ships arrive here. However eggs masses on aircraft are another matter. There are direct flights from Seattle and Vancouver to New Zealand and it is quite conceivable that egg masses could be transported to NZ on aircraft from there. So if the attempts to eradicate the AGM in Western North America fail, NZ could be at risk.
We have written to USDA entomologists asking to be kept up to date with the situation and have requested illustrative material for distribution to quarantine officers etc. In the near future we will be writing a background paper and making some recommendations to MOF Head Office.
(John Bain & Paddy Walsh)
This information is intended for general interest only. It is not intended to be a substitute for specific specialist advice on any matter and should not be relied on for that purpose. Scion will not be liable for any direct, indirect, incidental, special, consequential or exemplary damages, loss of profits, or any other intangible losses that result from using the information provided on this site.
(Scion is the trading name of the New Zealand Forest Research Institute Limited.)
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