The following risk analysis for Asian Gypsy Moth is based on the methodology in Biosecurity Australia's guidelines on Import Risk Analysis for Plants and Plant Products (2001).

Entry Potential
Rating = High

Egg masses are often carried by cars, trucks, trains or boats, on logs, containers, ships. Accidental introduction represents a risk in all temperate countries where it is not yet present (CABI, 2002). Viable Asian Gypsy Moth eggs have been continuously intercepted on cargo from Asia.

Establishment Potential
Rating = High

Asian gypsy moth has a wide host range and is known to feed on foliage of over 600 tree and plant species that are found in commercial forestry, horticulture and amenity plantings and wilderness areas.

Spread Potential Following Establishment
Rating = High

Larvae can spin silken threads and spread long distances in the wind. Females can fly up to 40km.

Economic Impact
Rating = High

In the gypsy moth's native range in Eurasia, outbreaks sometimes occur, but they tend to be localized and of short duration. Severe defoliation results in reduced growth increment, crown dieback, but tree mortality is only occasionally observed. This is in contrast to North America, where outbreaks tend to be more frequent and of longer duration. Two to three years of complete defoliation often results in significant tree mortality, particularly during drought conditions. This difference may be due in part to the absence of certain natural enemies.

L. dispar is considered the most important forest pest in north-eastern USA. Over the last 25 years over 26 million hectares were defoliated. In Pennsylvania in 1981 alone, timber loss was estimated to be more than US$ 72 million (Montgomery and Wallner, 1988). As the range of the gypsy moth continues to expand, these impacts are also likely to increase (Liebhold et al., 1997). The most significantly impacted economic resource has been oak timber.

Environmental Impact
Rating = High

The environmental impact of the gypsy moth in its introduced range in North America appears to exceed that in its native range in Eurasia. Oaks are more susceptible to defoliation, thus repeated gypsy moth outbreaks have contributed to a regional decline in the component of oak in eastern North American forests (Morin et al., 2001).

Although the pest has not evolved with eucalyptus species, it readily feeds on many, highlighting its potentially significant impact on both commercial and conservation forests.

In the US, over 1 million ha of forests have been aerial sprayed with pesticides for gypsy moth control and this may have serious impacts on both terrestrial and aquatic non-target organisms.

Conclusions
Overall risk: Rating = High