forest pest insects – Page 19 – Center for Invasive Species Prevention

Hawaii’s unique forests now threatened by insects and pathogens – APHIS & State should act

We have known since Darwin that oceanic islands can be cradles of speciation & endemism. Hawai`i exemplifies the phenomenon. Ninety-eight percent of native flowering plants are endemic (Cox). The density of native insect species in Hawai`i is higher than on mainland North America (Yamanaka).

We have known since Elton or earlier that oceanic islands are highly vulnerable to bioinvasion because their unique species did not evolve defenses against predation, herbivory, competition, or diseases; or the ability to adapt to changed soil chemistry or increased fire frequency.

Chapter 8 of the Office of Technology Assessment study of harmful invasive species states:

“Hawaii has a unique indigenous biota, the result of its remote location, topography, and climate. Many of its species, however, are already lost, and at least one-half of the wild species in Hawaii today are non-indigenous. New species have played a significant role in the extinction of indigenous species in the past and continue to do so. Hawaii, the Nation, and the world would lose something valuable as the indigenous fauna and flora decline.”

I apologize for not addressing the disasters wreaked on Hawai’i’s fauna and non-arboreal flora by invasive mammals and birds, plants, and such animal diseases as avian malaria and avian pox. For more on these topics, see the other sources listed below and the websites maintained by the Hawai`i Invasive Species Council and Coordinating Group on Alien Pest Species. Cox notes that alien species span all trophic groups and threaten the complete replacement of the native terrestrial biota.

Outside of land clearing for ranches and other uses, much of the damage to Hawaii’s native forest trees has been caused by introduced mammals – especially pigs and goats; and invasive plants. Few of the enormous number of non-native insects that have established in Hawai`i appear to have attacked native trees. More than 2,600 non-native insects have been introduced; their number equals three-quarters of the NIS insects established in North America, yet Hawai`i constitutes less than 0.01% of the area of North America. The ratio of non-native to native insect species is higher for Hawai`i than for the other geographic areas studied by Yamanaka and colleagues (mainland North America, “mainland” Japan, and two offshore Japanese islands) (Yamanaka).

More than 13% of the non-native insects (=~350) in Hawai`i were introduced intentionally for biological control of agricultural pests and non-native plants (Yamanaka). Cox, Elton, and the Office of Technology Assessment discuss briefly the sometimes damaging effects of these deliberate introductions.

I am aware of only one NIS insect that has seriously threatened a native tree species: the Erythrina gall wasp, which killed many native wiliwili trees as well as lots of introduced coral trees planted in towns and as windbreaks. Biocontrol agents have helped prevent continuing damage from the gall wasp.

Disease pathogens have so far proved greater threats to Hawaiian native trees than introduced insects. Koa wilt is killing koa, especially at lower elevations. It is not certain whether the pathogenic Fusarium fungus is introduced or native; it has been found on all four major islands. Koa is second only to `ohi`a (see below) in abundance in mid to upper elevation Hawaiian forests. It is extremely important ecologically and culturally (koa was the tree from which large, ocean-going canoes were made). Koa also has a wood valued for a range of uses.

`Ohi`a lehua is the most widespread tree on the Islands, dominating approximately 80% of Hawai`i’s remaining native forest (about 965,000 acres, 1500 square miles). These forests are home to Hawai`i’s one native mammal (Hawaiian hoary bat) and 30 species of forest birds (Loope and LaRosa). One threat to `ohi`a comes from `ohi`a or eucalyptus rust. Detected in April 2005, it had spread to all the major islands by August. Fortunately, the strain of `ohi`a rust established in Hawai`i is not very virulent on `ohi`a, but it has killed many plants of an endangered native shrub, Eugenia koolauensis and in Australia it has killed many plants in the Myrtaceae family. Hawaiian conservationists worry that a different, more virulent, strain might be introduced on plants or cut foliage shipped to the Islands from either foreign sources or the U.S. mainland.

A new, apparently more damaging, pathogen was detected in 2010. This new disease is caused by two newly discovered species of the fungal genus Ceratocystis — Ceratocystis lukuohia and C. huliohia. By October 2015 the disease has killed 50% of the `ohi`a trees in several scattered locations totaling 6,000 acres on the southeast lowlands of Hawai`i (the “Big Island”). Tree mortality was nearing the boundary of Hawaii Volcanoes National Park. Hawaii Volcanoes pioneered methods for controlling invasive pigs and plants that threatened to destroy the Park’s forests. Through 40 years of sustained effort, Hawaii Volcanoes has brought those threats under control. Now the Park faces loss of its invaluable `ohi`a forest to this pathogen – which will be infinitely harder to keep out of the Park. (For updates on “rapid ohia death” visit the write-up here.)

The Hawai`i Department of Agriculture has adopted an emergency regulation aimed at preventing transport of infected wood or tree parts from the Big Island to other islands.

Although tree-killing insects and pathogens have so far not been as damaging in Hawai`i as might be expected, the Islands are highly vulnerable due to the large volumes of cargo and people from around the globe which land on the Islands and the few tree species native there. The Erythrina gall wasp has island-hopped from the east coast of Africa to Hawai`i and many islands in between. `Ohi`a rust is native to tropical America and probably reached the islands on cut stems used in floral decorations. It is unknown where the Ceratocytis fimbriata strain evolved or how it reached Hawai`i.

USDA APHIS is responsible for preventing introduction of new plant pests to Hawai`i from non-U.S. jurisdictions (as well as from Guam). APHIS has traditionally paid little attention to plant pests that are thought likely to threaten “only” Hawai`i but not plant (agricultural) resources on the mainland.

Hawaiian authorities are responsible for preventing introductions from the Mainland – but they struggle with inadequate resources to address the huge volumes of incoming freight and they sometimes hesitate to act. (Hawai`i Department of Agriculture considered restricting shipments of foliage in the Myrtacea to minimize the risk of introduction of a new strain of `ohi`a rust, but in the end did not adopt such a measure.)

Hawai`i’s unique biota is an irreplaceable treasure. All Americans should act to prevent introduction additional introductions to the Islands.

SOURCES:
Cox, George W. Alien Species in North America and Hawaii Impacts on Natural Ecosystems 1999
Elton, Charles S. The Ecology of Invasions by Animals and Plants 1958; see especially Chapter 4: The Fate of Remote Islands
Loope, L. and LaRosa, A.M. `Ohi`a Rust (Eucalyptus Rust) (Puccinia psidii Winter) Risk Assessment for Hawai`i
U.S. Congress Office of Technology Assessment. 1993. Harmful Non-Indigenous Species In the United States. OTA-F-565; available at http://govinfo.library.unt.edu/ota/Ota_1/DATA/1993/9325.PDF

Yamanaka, T., N. Morimoto, G.M. Nishida, K. Kiritani, S. Moriya, A.M. Liebhold. 2015. Comparison of insect invasions in North America, Japan and their Islands. Biol Invasions DOI 10.1007/s10530-015-0935-y

Posted by Faith Campbell

Californians – regulate firewood! Protect your trees!

A new outbreak of the goldspotted oak borer raises again the question of why California does not outlaw the movement of untreated firewood.

goldspotted oak borer

This beetle – which has already killed more than 80,000 oak trees! – has been detected in the town of Green Valley, a small town in Los Angeles County north of the city, and inside the boundaries of the Los Padres National Forest. The first surveys found 27 coast live oak trees with symptoms of beetle attack.
The beetles in Green Valley are genetically identical to those in San Diego County – strongly indicating that the outbreak was started by people moving firewood out of the infested area.
As I noted in my blog dated July 15, the California Department of Food and Agriculture (CDFA) has so far refused to adopt regulations governing movement of firewood. While CDFA and other entities have sponsored billboards, flyers, and other outreach materials to educate people about the risk associated with firewood, the failure to ban firewood movement puts oaks throughout the state at risk.

areas of California in which oaks are at risk to GSOB (redder areas at greatest risk)

A second pest – the polyphagous shot hole borer and its associated Fusarium fungi – threatens a much wider range of trees. It is currently established in Los Angeles, Orange, San Bernardino, Riverside, and San Diego counties. It is known to attack Coast live oak, valley oak, Engelmann oak, California sycamore, big leaf maple and box elder, cottonwood, alder, and ash. This beetle, too, can be moved in firewood.
Californians should ask Governor Brown to adopt regulations restricting movement of untreated firewood. Act now! to protect your trees from goldspotted oak borer, polyphagous shot hole borer, and other non-native insects.
Posted by Faith Campbell

Wood Packaging – Customs Efforts & Recent Detections

As noted in my blog of July 15, damaging pests continue to enter the country in wood packaging. The most comprehensive study indicates that tree-killing pests are found in an estimated 13,000 containers entering the country each year – or 35 per day.
These pests are present despite requirements adopted 9 or more years ago that wood packaging be treated.

Types of cargo packaged in wood are inspected by agricultural specialists within the Bureau of Customs and Border Protection , a division of the Department of Homeland Security. CBP agricultural specialists work at 167 sea, air and land ports of entry. See an article about CBP efforts to curb introductions of tree-killing pests posted at http://www.cbp.gov/frontline/2014/12/frontline-december-forest-prime-evil.

CBP agriculture specialists in Laredo, Texas, examine a wooden pallet for signs of insect infestation. [Note presence of an apparent ISPM stamp on the side of the pallet] Photo by Rick Pauza

According to the CBP in the above article, the types of commodities imported that have the highest rates of SWPM-related pest interceptions are metal and stone products (including tile), machinery (such as automobile parts and farm equipment), electronics, bulk food shipments and finished wood articles.
These imports have a long-standing record of pest presence – as described in Chapter 4 of my lengthy report on tree-killing pests.

According to the CBP , 48% of the wood packaging entering the country that does not comply with the treatment requirements comes from Mexico. Mexican maquiladoras are factories that import material and equipment duty-free, then assemble a wide range of products – auto parts, apparel, electronics, furniture, and appliances. Mexico’s 3,000 maquiladoras account for half of Mexico’s exports.
China has the second worst record.
Of course, we import lots of stuff from both countries! However, the China situation is particularly disturbing because the U.S. has required that wood packaging from China be treated since the beginning of 1999 – 16 years!
The ports receiving highest numbers of shipments with non-compliant wood packaging materials have consistently been those along the U.S.-Mexico border, especially in Texas: Laredo, Pharr, more recently Brownsville & Houston. Other ports receiving high volumes of non-compliant wood packaging include Blaine, Washington; Long Beach, California; and Romulus, Michigan.

USDA APHIS and CBP have cooperated in a program under which insect larvae found in wood packaging are identified as to species. In recent years, they have studied larvae detected in wood packaging from eight ports – Long Beach, Seattle; 2 ports in Florida; and three cities on the Texas-Mexico border. (Remember, there are 167 ports of entry across the country, so this sample represented 5% of all ports.) Found at these ports were an unreported total of insects, including 116 individuals in the same family as Asian longhorned beetle (Cerambycids). Forty-three were from China (including 5 ALB), 20 from Russia, and seven from Mexico (Philip Berger, APHIS, at the annual meeting of the Continental Dialogue on Non-Native Forest Insects and Diseases, November 2014)

Most familiar – and frightening! – examples of pests introduced via wood packaging include Asian longhorned beetle, emerald ash borer, redbay ambrosia beetle and its accompanying fungus, and possibly polyphagous shot hole borer and its accompanying fungus – all described here.

The prospect of receiving additional insects from Asia scares everyone. What if a new pest is as bad as the four we already have? The emerald ash borer has already caused the removal of an estimated 50 million trees and continues to spread to ash trees – and now white fringe trees – throughout America east of the Great Plains. Laurel wilt disease (transmitted by the redbay ambrosia beetle) is rapidly eradicating redbay trees in the southeast, including in Everglades National Park – one of the icons of the American conservation movement. The Asian longhorned beetle has already caused removal of more than 124,000 trees from our cities, suburbs, and nearby woodlands – at a cost to federal taxpayers of more than $500 million. If it escapes eradication programs, it threatens trees in 10% of America’s forests. The polyphagous shot hole borer threatens numerous tree species that, collectively, make up more than half the trees planted in urbanareas in Southern California.

While no one denies the threat from insects native to Asia, we should not be complacent about insects from Mexico. Although we are neighbors, our forests are separated by deserts – allowing insects to evolve there to which our trees are vulnerable. Three wood-boring beetles native to Mexico and possibly some U.S. border states are already causing havoc to U.S. trees – goldspotted oak borer, soapberry borer, and walnut twig beetle and its accompanying fungus (all described here). The first two were introduced to vulnerable forests through movement of firewood, not wood packaging. The third – the walnut twig beetle – might be native to California, although thousand cankers disease is killing native California walnuts throughout the state so something is different than it used to be.

goldspotted oak borer

When Customs officials detect wood packaging that does not comply with ISPM #15 (“noncompliance” means one of three things: the wood does not bear the ISPM #15 stamp; or the stamp appears to be fraudulent; or signs of pests are detected), that wood must be re-exported immediately, usually with the associated commodity. If any insects present pose an immediate risk of introduction, e.g., if adults are emerging, the shipment might need to be fumigated before re-export.
Re-exported shipments – and any treatments – cause importers to lose income and face costly delays. Still, the continuing presence of non-compliant wood packaging indicates that these inconveniences are insufficient to prompt importers to take all precautions possible to ensure that packaging used by their suppliers and brokers comply with the requirements.

Why don’t importers use alternative packaging made from plastic, steel, or composites that would not harbor tree-killing insects? Plastic pallets also weigh much less than wooden ones, so transport costs are reduced. Customs has pointed out the advantages. … Still, packaging material made from wood is comparatively plentiful, cheap, easy to repair, biodegradable. So it continues to dominate the market.
What steps can be taken by the U.S. government and importers to minimize the presence of insects in packaging?
• U.S. policy allows an importer to be caught 5 times in 1 year with wood packaging that does not comply with the regulatory requirements. Requirements adopted a decade or more ago should be enforced strictly! The Bureau of Customs and Border Protection and USDA APHIS should instead penalize all importers whose wood packaging does not comply with the regulations.
• The Bureau of Customs and Border Protection should incorporate the wood packaging requirements into its “Customs-Trade Partnership Against Terrorism” (C-TPAT) program .
• USDA APHIS should re-examine the economic pros and cons of requiring importers to switch to packaging made from materials other than wooden boards. The new review should incorporate the high economic and ecological costs imposed by insects introduced via the wood packaging pathway.
• The President’s Office of Management and Budget should allow APHIS to finalize regulations – proposed in 5 years ago! – that would apply the same treatment requirements to wood packaging used in trade between the US and Canada. (Canada has been ready to adopt this measure for several years.)
• Importer’ contracts with suppliers routinely specify penalties for delivery delays; the contracts should be amended to add penalties for noncompliant wood packaging.
• A decade ago, USDA APHIS funded research which developed an ingenious method for detecting mobile pests inside a container. It was an LED light attached to a sticky trap. Placed inside a container, the light attracted snails, insects and possibly other living organisms. The whole mechanism was attached to a mailing container that could be pre-addressed for sending to a lab that could identify the pests. Why was this tool never implemented?

Posted by Faith Campbell

Wood-borers in Wood Packaging: How Did We Get to This Crisis?

shipping container being unloaded at Long Beach

The rising numbers of tree-killing wood-boring insects introduced to the U.S. (see blogs from July 15 and August 3 & fact sheet and sources linked there) are a result of ballooning of trade volumes and use of wood packaging.

This irruption of trade was made possible by adoption of the shipping container to transport a wide range of goods.Moving from place to place are not just finished products but also components that originated in one country and that are to be assembled in another country.

How the shipping container revolutionized trade and manufacturing is detailed by Marc Levinson in his book, The Box: How the Shipping Container Made the World Smaller and the World Economy Bigger (Princeton University Press 2008). The transformation affected not only trade between countries, but also within countries, with some regional economies growing while others faltered.

Dr. Levinson recognizes that he has not addressed environmental damage caused by massive movement of cargo. While Dr. Levinson does not explain which damage he is thinking about, I doubt that he includes introductions of non-native wood-boring pests.

(I don’t know enough about the ballast water pathway to understand the impact of containerized shipping on introductions of aquatic invaders, but it seems likely to be an important factor through three factors: directing trade to new port areas; the ships’ huge size; and taking on of ballast water for those segments of a voyage carrying fewer filled cargo containers. On the other hand, Dr. Levinson says that a balance of cargo moving both ways on a trade route is an important factor in determining which ports thrive.)

Before containers, port costs represented the highest proportion of transport costs. Those costs are no longer an important consideration in determining manufacturing and transport choices. Nor is distance as important as before. What is most important are ports that can move large volumes of goods efficiently. The manufacturer or retailer at the top of the chain finds the most economical place for each step in the manufacturing and assembly process without regard to its location.

The containerization revolution was rapid. Containers were first used in international trade in 1966; within three years, nearly one-third of Japanese exports to the U.S. were containerized, half of those to Australia. In the decade after containers were first used in international trade, the volume of international trade in manufactured goods grew more than twice as fast as the volume of global manufacturing production, 2.5 times as fast as global economic output. Large numbers of specialized container ships were built, at ever-increasing sizes. The largest container ship in 1969 could carry 1,210 20-ft containers. By the early 2000s, ships being built to carry 10,000 20-foot containers; or 5,000 40-foot containers.

When Dr. Levinson wrote his book in 2005, the equivalent of 300 million 20-foot containers were crossing the world’s oceans each year.

The container revolution interacted with “just-in-time” manufacturing, which required rapid and reliable transport. Large companies signed written contracts with suppliers and shippers which included penalties for delays.

In the U.S., Long Beach quickly became the principal port because it (as well as Oakland and Seattle) had excellent rail connections to the interior. By 1987, one-third of containers from Asia destined for the East Coast landed at Long Beach and crossed the U.S. by rail. Perhaps counter to our expectation, only one-third of containers entering southern California in 1998 contained consumer goods. Most of the rest contained intermediate or partially processed goods as part of the new international supply and manufacturing chain.

Containers at Long Beach

On the East coast, Charleston SC and Savannah similarly grew because of transport connections – this time, primarily highways.

So, global trade is huge and growing; and the shipping container moves immense quantities of goods from one ecosystem to another and provide shelter for a vast range of hitchhiking living organisms (in addition to insects in the wood, there can be other insects’ eggs attached to the sides of the container, snails, weed seeds, even vertebrates – a raccoon once staggered out of a shipping container that had crossed the Atlantic from the U.S. to France!).

We need to imagine, test, and apply a variety of tools to suppress the numbers of living organisms traveling in shipping containers.

For example,
• if importer-supplier contracts specify penalties for delivery delays, we should ask why don’t importers amend the contracts to add penalties for non-compliant wood packaging?
• Might the Bureau of Customs and Border Protection incorporate the wood packaging requirements into its “Customs-Trade Partnership Against Terrorism” (C-TPAT) program.
• A decade ago, USDA APHIS funded research which developed an ingenious method for detecting mobile pests inside a container. It was an LED light attached to a sticky trap. Placed inside a container, the light attracted snails, insects and possibly other living organisms. The whole mechanism was attached to a mailing container that could be pre-addressed for sending to a lab that could identify the pests. Why was this tool never implemented?

We can’t stop the trade, but we can be much more aggressive in adopting measures to minimize pest introductions.

Posted by Faith Campbell

Non-Native Pest Threat to Forests of the West Coast

As we Americans import more stuff, the risk of new pest introductions rises, too. Many tree-killing insects arrive as larvae living in crates, pallets, and other forms of wood packaging. While the USDA requires that incoming wood packaging be treated to prevent pests, this regulation has not prevented pests from entering the country on wood packaging.

piece of wood packaging with Cerambycid larva; detected in Oregon

A study has found that perhaps 35 shipping containers harboring tree-killing pests reach our ports each day (Haack et al. 2014). At this rate, in just 35 years, America might suffer invasion by more than 100 new wood-boring species. This would result in a tripling of borers introduced to U.S. (Leung et al. 2014).

Already, wood-boring beetles have been among the most damaging tree-killing pests introduced to the U.S. Our environment certainly doesn’t need invasions by three times as many new wood-borers!

West-coast ports receive lots of incoming shipping containers. Long Beach alone receives about half of the nearly 25 million shipping containers arriving at the U.S. each year. So it is alarming that high-risk insects, including the Asian longhorned beetle (ALB), continue to be found in wood packaging (Berger 2014).

Imported goods that are heavy are more likely to be packaged in wood and that thus pose the greatest pest risk. The highest risk commodities are
• machinery (including electronics) and metals;
• tile and decorative stone (such as marble or granite counter tops) (Harriger 2014).
The west coast ports of Seattle, Los Angeles/Long Beach, and San Francisco all rank in the top 15 out of 3,500 (1/2 of 1%) cities nation-wide for imports of tile and decorative stone, machinery and metals (Colunga-Garcia et al. 2009).

Not only do west coast cities import high volumes of risky goods; a significant proportion of the trees growing in those cities are vulnerable to these pests. Seattle’s three to four million trees belong to more than 300 species – although a mere seven genera constitute two-thirds of the trees (Ciecko et al. 2012). It has been estimated that just four non-native pests (ALB, gypsy moth, emerald ash borer, and “Dutch” elm disease) could cause $3.5 billion in damages. The ALB alone threatens 39.5% of all trees lining the city’s streets (City of Seattle 2013).

San Francisco has an estimated 669,000 trees; 12% are at risk to the ALB (Nowak et al. 2007). Apparently no one has yet estimated the numbers of trees at risk to sudden oak death (SOD), goldspotted oak borer (GSOB), or polypagous shot hole borer (PSHB).

It is essential that USDA APHIS act more aggressively to prevent additional introductions of pests via wood packaging. (For a longer discussion of the wood packaging pathway, visit my previous blog posted on July 15th). In brief:
• APHIS & the Bureau of Customs and Border protection should penalize all importers whose wood packaging does not comply with decade-old regulatory requirements.
• The Bureau of Customs and Border Protection should incorporate the wood packaging requirements into its “Customs-Trade Partnership Against Terrorism” (C-TPAT) program
• APHIS should re-consider the advantages of requiring importers to switch to packaging made from materials other than wooden boards.
• The President’s Office of Management and Budget should allow APHIS to finalize regulations – proposed in 5 years ago! – that would apply the international standard’s treatment requirements to wood packaging used in trade between the US and Canada. (Canada has been ready to adopt this measure for several years.)

SOURCES
Berger, P. Executive Director, PPQ Science and Technology, Presentation to the Continental Dialogue on Non-Native Forest Insects and Diseases, November 3, 2014

Ciecko, L., K. Tenneson, J. Dilley, K. Wolf. 2012. Seattle’s Forest Ecosystem Values: Analysis of the Structure, Function, and Economic Benefits; August 2012; GREEN CITIES RESEARCH ALLIANCE; City of Seattle Urban Forest Stewardship Plan 2013.

City of Seattle Urban Forest Stewardship Plan 2013.

Colunga-Garcia, M., R.A. Haack, and A.O. Adelaja. 2009. Freight Transportation and the Potential for Invasions of Exotic Insects in Urban and Periurban Forests of the US. J. Econ. Entomol. 102(1): 237-246 (2009); and raw data for the study provided by the authors.

Haack, R.A., F. Herard, J. Sun, J.J. Burgeon. 2009. Managing Invasive Populations of Asian Longhorned Beetle and Citrus Longhorned Beetle: A Worldwide Perspective. Annu. Rev. Entomol. 2010. 55:521-46.

Haack RA, Britton KO, Brockerhoff EG, Cavey JF, Garrett LJ, et al. (2014) Effectiveness of the International Phytosanitary Standard ISPM No. 15 on Reducing Wood Borer Infestation Rates in Wood Packaging Material Entering the United States. PLoS ONE 9(5): e96611. doi:10.1371/journal.pone.0096611

Harriger, K. 2014. Presentation to the Continental Dialogue on Non-Native Forest Insects and Diseases, November 3, 2014

Leung, B., M.R. Springborn, J.A. Turner, E.G. Brockerhoff. 2014. Pathway-level risk analysis: the net present value of an invasive species policy in the US. The Ecological Society of America. Frontiers of Ecology.org

Nowak, D.J., R.E. Hoehn III, D.E. Crane, J.C. Stevens, J. T. Walton. 2007. Assessing Urban Forest Effects and Values: San Francisco’s Urban Forest. USDA Forest Service. Northern Research Station. Resource Bulletin NRS-8.

posted by F.T. Campbell

California Government Ignores Threats to State’s Hardwood Trees

CDFA Fails to Regulate Movement of Firewood

Many of California’s hardwood trees are threatened by two introduced insects – the goldspotted oak borer (or here) and the polyphagous shot hole borer or here. Both are established in southern California, but threaten trees throughout the state.

One of the most likely pathways by which these insects can be moved to vulnerable areas is by the transport of firewood. Yet the California Department of Food & Agriculture (CDFA) has not regulated firewood movement.

goldspotted oak borer

Two Tree-Killers

California’s oaks – including California black oak, canyon live oak, coast live oak, Engelmann oak, Shreve’s oak, and valley oak – are threatened by one of both of these insects. The goldspotted oak borer (GSOB) is established in San Diego County with additional outbreaks in Riverside and Orange counties. In less than 20 years, GSOB has killed nearly 100,000 black oaks in these counties. GSOB also kills coast live and canyon oaks. These oaks growing throughout the state are at risk to GSOB.

areas of California at risk to goldspotted oak borer

The polyphagous shot hole borer (PSHB) carries a fungus. The beetle-disease complex has been found in areas of Los Angeles, Orange, San Bernardino, Riverside, and San Diego counties. The insect attacks more than 300 species of trees, shrubs, and vines; the fungus survives in more than 100 of these.

Trees attacked by PSHB include: 11 species native to southern California; 13 agriculturally important trees, such as avocado; and 53 species that, cumulatively, constitute more than half of all trees planted in urban areas of southern California. While PSHB might not be able to reproduce in all these hosts, it is known to reproduce in five types of maples, five types of oaks, a couple of willows, as well as a poplar, a sycamore, and an alder.

areas of southern California where polyphagous shot hole borer is established

Many of the vulnerable tree species are important components of riparian communities in southern California. PSHB apparently attacks only trees that receive enough water to support the fungus – hence the threat to riparian areas. Since PSHB comes from tropical Southeast Asia, its spread to the north and upslope would probably be limited by winter cold. Nevertheless, a wide variety of trees in large parts of the state appear to be at risk.

Among the natural areas at risk to one or both of these pests is Yosemite National Park. The oak trees growing in Yosemite Valley are black oaks, vulnerable to GSOB.

Both State & National Park Service have Failed to Act

Despite the threat to natural and even agricultural resources throughout the state, CDFA has not adopted regulations governing the movement of firewood – the pathway most likely to spread these pests. CDFA has funded outreach efforts, including flyers, posters at campgrounds, and highway billboards. Broad coalitions – made up of academics; county agriculture and parks officials; federal forestry and public lands staff; and others –are educating the public and firewood vendors about the risk and asking them not to move firewood. But when people ask whether there is a law against moving firewood, these volunteers must answer, “no”. This undermines their message!

Yosemite and the other National parks in the region also have not adopted regulations prohibiting visitors from bringing in firewood obtained outside the park. While the National Park Service discourages people from bringing firewood into the Park from farther than 50 miles away, this request is buried in the detailed description of camping regulations or here.

The other National parks in California also do not regulate visitors’ movement of firewood.

It is past time for state and federal agencies to accept their responsibility to protect priceless natural and agricultural resources by adopting regulations to control the movement of firewood.