81 



well as in Michigan. APHIS has quarantined movement of logs, Christmas trees, 

 and nursery stock of coniferous species from the infested states. 



A spruce beetle Ips typographus was discovered in Erie, Pennsylvania in 1993 

 (Hofacker 1993). "This insect is one of the most destructive pests of spruce in Eu- 

 rope; one outbreak destroyed an estimated 30 million cubic meters of wood. The bee- 

 tle also killed millions of trees in Japan." (Smith). APHIS and the Forest Service 

 are searching to determine whether the beetle has become established in the area 

 (Hofacker 1993). 



Indeed, Forest Service staff have documented over 300 species of exotic pests, in- 

 sects and diseases, that have been introduced to North American trees, tree nurs- 

 eries, and wood products (Millers et al. unpublished manuscript and personal com- 

 munication). 



APHIS must not weaken existing regulations on importation of nursery stock (the 

 apparent or known source of eight introductions — See Appendix B). APHIS must 

 also move ahead in adopting at least equally stringent regulations governing log and 

 other unprocessed wood imports. Greater attention should be given to fungi^ and 

 other pathogens, which appear to pose a greater threat than do insects, APHIS' tra- 

 ditional emphasis.^ 



APHIS should ensure that its regulations adequately address two problems high- 

 lighted in the Chilean risk assessment: the prevalence of bark-inhabiting insects on 

 "de-barked" logs and the apparent frequency w.th which pests are transported on 

 dunnage, crates, or pallets (USDA Forest Service 1993). 



Furthermore, APHIS and the Forest Service should study virulent diseases and 

 arthropods in their native countries and apply that knowledge to delay as long as 

 possible their introduction here and to combat them effectively when they do arrive 

 (Boyce 1961). For example, APHIS should expand its monitoring of gypsy moth pop- 

 ulations from Siberia to Europe, where Asian or hybrid gypsy moths are now 

 present In many cases, such studies will require multi-disciplinary risk assessment 

 teams similar to those which evaluated possible pest risks associated with wood im- 

 ports from Siberia, New Zealand, and Chile. 



Responsible agencies must be constantly vigilant First, it is often impossibleto 

 predict in advance which foreign organisms will prove devastating if introduced. The 

 two Asian fungi that have virtually eliminated the American chestnut and the 

 American elm from the forest cause relatively minor damage to many of the Asian 

 chestnuts and elms which are their natural hosts (Lattin; APHIS 1994). 



Second, pest organisms can evolve more virulent strains. Since arriving in Amer- 

 ica, Dutch elm disease has evolved more aggressive strains which now are spreading 

 in North America (Burkman, et al.) and adding to the threat in Europe as well 

 (USDA Forest Service 1991b). The European strain of Scleroderris canker {Ascocalyx 

 abietina = Gremmeniella abietina) has apparently replaced the less virulent "North 

 American strain" (Skilling). While the outbreak of the 1970s has now subsided with 

 changes in weather and the killing of the lower branches where infection first oc- 

 curs, damaging outbreaks may resume in the future. 



Insects can vary in their virulence— the Asian and hybrid gypsy moths are both 

 more mobile and eat a greater variety of trees than do European gypsy moths. In- 

 sects can also switch hosts. The pear thrips has proved able to shift from fruit 

 trees— which are in the rose family (Rosaceae)— to the sugar maple Acer 

 saccharum — in the maple family (Aceraceae). 



New Zealand has stringent pest-exclusion programs. Because of documented ille- 

 gal imports of raw wood in "full container load" shipping containers, New Zealand 

 adopted the Forest Produce Import and Export Regulations in 1989. This statute re- 

 quires prior notice to the quarantine officer of estimated time of arrival of any ves- 

 sel importing forest produce, and provision of a full manifest (including any pallets). 

 Forest produce is defined to include timber and dunnage; dunnage does not include 

 packing cases or pallets. If a quarantine inspector were to suspect infestation, he 

 or she may require quarantine and treatment according to an appropriate prescrip- 

 tion. The costs of inspection, excluding dunnage inspection, such as transport to a 

 quarantine facility, treatment, etc. are paid by the importer (New Zealand). 



1 Examples of introduced diseases which have or are now causing serious decline of species 

 include: Chestnut blight Crypphonectria parasitica (Murrill); "Dutch" elm disease Ceratostomella 

 ulmi (Buisman); White pine blister rust Cronartium ribicola (Fischer); Scleroderris canker 

 Acocalyx abietina (Lagerberg); Dogwood anthracnose Discula destructiva (Redlin); beech bark 

 disease Nectna coccinea var. faginata (Lohman, Watson & Ayers), butternut canker Sirococcus 

 clavigignentijuglandacearum, Port-Orford-Cedar root rot Phytophthora lateralis (Tucker & 

 Milbrath). Truly damaging exotic insects do occur; examples include the balsam woolly adelgid, 

 hemlock woolly adelgid, and probably the Asian strain of gypsy moth. 



