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Six of the "representative" pest species were examined in detail. The findings on 

 these six pests are briefly summarized below. 



Asian gypsy moth 



The Asian strain of the gypsy moth (which belongs to the same species — Lymantria 

 dispar—^as the European insect) feeds upon more than 500 species of plants (Gibbon 

 1992), including many conifers and hardwood species. The Asian gypsy moth has a 

 "moderate" potential to kill keystone hardwood tree species in healthy forests, and a 

 "high" potential in stressed forests. The potential for extensive infestation of conifer 

 forests is largely unknown but probably ranges from moderate to high (USDA Forest 

 Service 1991b). Furthermore, unlike the European gypsy moth, the female Asian 

 moth can fly up to 24 miles, carrying 600 to 700 eggs (USDA Forest Service 1991b, 

 Gibbon 1992). 



The Asian gypsy moth reached various Pacific port cities in North America in 1991 as 

 egg masses on ships transporting grain. The United Sutes and Canada immediately 

 implemented an emergency control program. Aggressive spraying of the biopesti- 

 cide. Bacillus thunngiensis ("Bt"). near the affected ports has apparently controlled 

 the infestations. Meanwhile, Canadian authorities banned all ships that had visited 

 potentially infested Siberian harbors from Canadian waters during the spring months 

 when the eggs were likely to be hatching (Oliver, personal communication). The United 

 States has relied on a voluntary agreement along the same guidelines. Both countries 

 are monitoring gypsy moth population cycles near Siberian and North American 

 ports. Asian gypsy moth infestations, however, would probably become extremely dif- 

 ficult to control if infestation repeatedly occurs at various Pacific ports. 



An outbreak of gypsy modis in North Carolina in July 1993 was found to include 

 Asian and European types, but predominantly hybrids between the two. This lime, the 

 insects had arrived on military equipment being shipped from Germany. Germany 

 and other European countries are experiencing heavy infesutions of gypsy moths this 

 year, which apparently include hybrids. Shipments of all types of cargo from Europe 

 could carry the insects to the United Sutes (USDA Forest Service and APHIS 1993). 



Nim moth 



Tlie nun moth {Lymantna monacha) is similar to the Asian gypsy moth in habits, 

 development, and host utilization. If introduced, it is likely to attack all western 

 conifers except pines. Tree mortality "is likely to be high." The potential area affected 

 is 172 million acres in the United States and additional areas of Canada (USDA For- 

 est Ser\ice 1991b). 



Pine wood nematode 



Se\eral Asian species of pine wood nematode, including Bunaphelendius mucronatus 

 and B. kolymmsis, are beliex-ed to pose the greatest threat to the Jeffrey and ponderosa 

 pines (Pinus ponderoia) and other hard pines (USDA Forest Ser\ice 1991b). Ponderosa 

 pine occupies nearly 5.7 million acres from British Columbia south into Mexico 

 (Lattin. personal communication; Skilling et aL 1986). 



Larch canker 



If introduced in the west (it is already present in eastern Canada and Maine), larch 

 canker (LachneUula wiUkommii) "could have a major impact on the 2 million acres of 

 western U.S. forest with 50 percent or more larch cover" While the western larch's 

 natural range is far from ports of entry, the canker might be spread on ornamental 

 larches (USDA Forest Ser\ice 1991b) 



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