forest pest insects – Page 14 – Center for Invasive Species Prevention

Unique Black Ash Wetlands – Threatened by Emerald Ash Borer

Another unique ecosystem being severely damaged by non-native tree-killing pests are the wetlands dominated by black ash (Fraxinus nigra). Black ash typically grows in fens, along streams, or in poorly drained areas that often are seasonally flooded. Such swamps stretch from Minnesota to Newfoundland; in the three states of Michigan, Wisconsin, and Minnesota, they cover a total of over 2 million hectares (Kolka et al. 2018).

Recent research allows us to understand the impending loss to these unique ecosystems that will be caused by the emerald ash borer (EAB).

Hydrology is the dominant factor that influences a host of ecosystem functions in black ash wetlands. Water levels are largely determined by a combination of precipitation and evapotranspiration rates. Black ash can thrive in wetter areas than most other tree species (Slesak et al. 2014). Water tables in these swamps are typically above the surface throughout early spring, followed by drawdown below the surface during the growing season with periodic rises following rain events. Water table drawdown coincides with peak evapotranspiration following black ash leaf out, demonstrating the fundamental control that this species has on animal and other plant communities (Kolka et al. 2018; Slesak et al. 2014).

Ecological Importance

Black ash generally dominate the canopy of these wetlands. Ash density can range from about 40% to almost 100%. Several other tree species are present, including northern white cedar (Thuja occidentalis), red maple (Acer rubrum), American elm (Ulmus americana) (Kolka et al. 2018), quaking aspen (Populus tremuloides), American basswood (Tilia americana), and bur oak (Quercus macrocarpa) (Slesak et al. 2014), balsam fir (Abies balsamea), balsam poplar (Populus balsamifera), and speckled alder (Alnus incana) (Youngquist et al. 2020). Black ash, by maintaining low water levels during the growing season, creates conditions under which these other trees can live but not thrive (summary of study by B.J. Palik, USDA Forest Service, here. Most other species lack the physiological adaptations of black ash or face pathogenic constraints (e.g., Dutch elm disease on American elm Ulmus americana) (Kolka et al. 2018).

Ash trees in these swamps are uneven-aged with canopy tree ages ranging from 130–232 years (Slesak et al. 2014). This complexity provides important habitat for many wildlife species, including ground beetle community assemblages (Kolka et al. 2018) and an abundance of aquatic macroinvertebrates. These are characterized and dominated by mollusks (Sphaeriidae, Lymnaeidae, Physidae), annelids (Lumbriculidae, Hirudinea), caddisflies (Limnephilidae, Leptoceridae), and dipterans (Chironomidae, Culicidae) (Youngquist et al. 2020).

A major concern is that loss of trees – especially ash – might result in open marshes dominated by grasses, especially lake sedge (Carex lacustris). Conversion to sedge-dominated marshes has been observed in areas where trees have been removed as part of experiments to test various ecosystem responses to loss of the ash component (Slesak et al. 2014). Even if other trees took the place of ash, the substitutes might not support the same animal communities (see below).

Impact of Emerald ash borer and loss of black ash

Black ash is highly susceptibility to the EAB (Engelken and McCullough, 2020), so scientists expect severe impacts of the invasion in ash-dominated wetlands and – to a somewhat lesser extent — in forested stream systems’ riparian areas (Engelken and McCullough, 2020). They expect cascading impacts on 1) hydrology; 2) plant communities; 3) wildlife; 4) Native American cultures; and possibly even storage of carbon in vegetation and soils (Kolka et al. 2018).

1) Hydrology

Experiments suggest that loss of ash will cause higher water tables, especially during late summer and fall (Kolka et al 2018). This will result from reductions in evapotranspiration as large trees are replaced by shrubs and grasses (see below) (Kolka et al. 2018; Slesak et al. 2014). The higher water table might be exacerbated if higher annual precipitation levels predicted by climate change models occur. On the other hand, these models also predict a simultaneous increase in longer droughts, which might partially counteract higher precipitation and reduced evapotranspiration (Kolka et al. 2018). If they occur, these possible increases in drought length and frequency might enhance the establishment of less water-tolerant non-ash tree species in former black ash wetlands.

2) Plant Communities

Higher water tables are expected to reduce tree densities and promote conversion to open or shrub-dominated marshes. Several of the possible alternative tree species do not thrive as well as black ash under current conditions (Kolka et al. 2018). However, new hydrologic conditions might make forest restoration even more difficult because herbaceous plants transpire less water than trees, thus exacerbating the rising water tables (Slesak et al. 2014).

In upper Michigan, experiments which killed ash by cutting or girdling did not lead to an increase in growth rates of the remaining canopy species despite the increase in available resources (e.g., sunlight and nutrients) – presumably because of the raised water table (Kolka et al. 2081).

While some studies have found that black ash seedlings and saplings dominated the woody component of the swamp understory up to three years after ash were experimentally removed (Kolka et al. 2018), Engelken and McCullough (2020) found only eight saplings and a single seedling.

Scientists have planted several tree species in experiments to see which might be used to maintain the forested wetlands in the absence of black ash. The results are a confusing mix. Some species grew well once established – but had low levels of seedling establishment. Some trees planted on elevated microsites (hummocks) had the greatest survival and growth rates. (For specific data, see Kolka et al. 2018). A further consideration is tree species’ ability to adapt to warming temperatures already evident and expected to increase in coming decades (Slesak et al. 2014).

Consequently, Slesak et al. (2014) think it is likely that the EAB invasion will alter vegetation dynamics and cause a shift to an altered ecosystem state (e.g., open marsh condition) with higher water tables. They caution that the degree of ecosystem alteration will vary depending on site hydrology, annual precipitation, and period of time necessary for establishment of deeper rooted vegetation.

3) Wildlife

Moreover, any changes in vegetation will also affect the biota in more subtle ways through altered nutrient cycles. Black ash leaf litter is highly nutritious, having some of the highest nitrogen, phosphorus, and cation contents of any hardwood forest species (Kolka et al. 2018). Black ash leaves also decompose faster than most alternative tree species’ leaves (summary of Palik USDA Forest Service, here; Youngquist et al. 2018).

Youngquist et al. (2018) studied litter breakdown, litter nutritional quality, and growth of a representative invertebrate litter feeder – larvae of a shredding caddisfly (Limnephilus indivisus). They found that the larvae’s risk of death increased by a factor of three times or more when caddisflies were fed American elm, balsam poplar, or lake sedge leaves compared to black ash leaf litter. Even when the larvae lived – but matured more slowly because of the lower nutrition value of the leaves – they would still be vulnerable because they must reach metamorphosis before pond dry-down. In any planting done to maintain forested quality of wetlands, need to consider the nutritional quality of the leaf litter provided by replacements. Speckled alder was only apparently acceptable substitute; it was second to black ash in acceptability to caddisflies (Youngquist et al. 2020)

In fact, Youngquist et al. (2020) concluded that plant and detritivore biodiversity loss due to EAB invasion could alter productivity and decomposition at rates comparable to other anthropogenic stressors (e.g., climate change, nutrient pollution, acidification). The result will be altered biogeochemical cycles, resource availability, and plant and animal communities.

Scientists are also concerned about the impact of ash tree mortality on forest connectivity. Conversion of wooded swamps to shrub-and sedge-dominated wetlands will result in the loss of important micro-habitats that are already limited across the forested landscape and may also reduce availability of critical habitat for migrating birds. These changes will exacerbate on-going changes in land use in the Great Lakes region that are causing loss of forest habitat and forest homogenization. As yet, the magnitude of the impact on wildlife is unclear (Kolka et al. 2018).

black ash baskets – displayed at 2006 conference
photo by Faith Campbell

4) Cultural importance – baskets

Native Americans living in the range of black ash have utilized the wood to make baskets and other tools for thousands of years. Baskets had numerous uses, such as packs for carrying items, fish traps, and for preparing food and storing household items. Ash items also had ceremonial uses and they are highly sought as gifts and in trade. The skill needed to select a good tree and work the wood is handed down through the generations and is an important part of tribes’ culture (Benedict 2010).

Discussion of these cultural traditions can be found as Powerpoints here and here.

A video is posted here.

USFS Research Efforts

Concerned by the spread of EAB and probable impact on black ash swamps, the USDA Forest Service has initiated major research studies with the goal of filling in the numerous knowledge gaps and developing management recommendations. A large-scale study using various manipulations to simulate the EAB invasion was initiated in the Chippewa National Forest in northern Minnesota in 2009. A companion study began in the Ottawa National Forest in Michigan in 2010 (Kolka et al. 2018). The Slesak, Youngquist, and Kolka publications cited in this blog report results of some of the studies in this project. Other studies of black ash conditions, including regeneration, at various stages of the EAB invasion wave are being carried out by Deb McCullough, Nate Siegert, and others. They are working at sites from Michigan to New England (D.G. McCullough, pers. comm.).

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report here.

For a great discussion of black ash basketweavers, see Anne Bolen, A Silent Killer: Black Ash Basket Makers are Battling a Voracious Beetle to Keep their Heritage Alive, American Indian Magazine, Spring 2020, available here.

SOURCES

Benedict, M. 2010. Ecology and the Cultural and Economic Importance of Black ash (Fraxinus nigra Marsh) for Native Americans May 2010 https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5191796.pdf

Engelken, P.J. and D.G McCullough. 2020. Riparian Forest Conditions Along Three Northern Michigan Rivers Following Emerald Ash Borer Invasion. Canadian Journal of Forest Research. Submitted

Kolka, R.K., A.W. D’Amato, J.W. Wagenbrenner, R.A. Slesak, T.G. Pypker, M.B. Youngquist, A.R. Grinde and B.J. Palik. 2018. Review of Ecosystem Level Impacts of Emerald Ash Borer on Black Ash Wetlands: What Does the Future Hold? Forests 2018, 9, 179; doi:10.3390/f9040179 www.mdpi.com/journal/forests

Slesak, R.A., C.F. Lenhart, K.N. Brooks, A.W. D’Amato, and B.J. Palik. 2014. Water table response to harvesting and simulated emerald ash borer mortality in black ash wetlands in MN, USA. Can. J. Forestry. Res. 44:961-968.

Youngquist, M.B., C. Wiley, S.L. Eggert, A.W. D’Amato, B.J. Palik, & R.A. Slesak. 2020. Foundation Species Loss Affects Leaf Breakdown and Aquatic Invertebrate Resource Use in Black Ash Wetlands. Wetlands. Society of Wetland Scientists

Posted by Faith Campbell

What the VLB Saga Tells Us About Detection Surveys

Setting Priorities for Surveillance

CBP inspects a pallet suspected for harboring an insect pest

Despite Customs and Border Protection’s heroic efforts to target inspection of wood packaging shipments, based on histories of non-compliance of specific importers’ wood packaging (which I have often praised), the majority of larvae occurring in wood packaging would probably not be intercepted by inspectors. Instead, they would be transported to the cargo’s intended destinations (Wu et al. 2020). I described these problems in the preceding blog about the velvet longhorned beetle (VLB).

As I have noted in the past, CBD detects an average of 800 shipments per year with non-compliant wood packaging. That figure is less than five percent of the 16,500 infested shipping containers that might enter the country each year, based on the estimate by Haack et al., (2014) that one tenth of one percent of incoming wood packaging might be infected.

So there is always a need to improve surveillance for pests that inspection fails to catch. We can do that in at least the following ways:

1) better target detection efforts on the most likely areas where a pest might establish

2) improve collection and use of pest-related information to determine probable hosts, pathways of movement, and potential impacts.

Discovering How the Pest Moves

Sometimes improvements must be linked to individual species – although assisted by knowledge about species with similar life histories, e.g., similar hosts or flight periods or about its close relatives (see Ray’s development of a VLB lure; full citation at end of this blog).

Other times, improvements might result from more generalizable adjustments.

For example, the pathway analysis undertaken by Krishnankutty and colleagues is one approach to improving geographic targetting. They analyzed aspects of the velvet longhorned beetle’s pathways of introduction: 1) the types of imports associated with VLB-infested wood packaging; 2) ports where the beetle has been detected in recent years; plus 3) the presence and calculated probable volume of imports for the types of commercial operations considered likely to transport the beetle.

This analysis required access to detailed data from many sources. They included 1) interception data revealing the types of products most often associated with infested wood and the intended destinations of intercepted cargoes; 2) the North American Industry Classification System data listing locations of businesses likely to utilize these products; 3) the beetle’s climatic requirements; and 4) the locations of actual detections of VLB as revealed by Cooperative Agricultural Pest Survey (CAPS) and other trapping programs.

Approaches to Learning More

Relying on traps to detect new pests has several advantages. These include the relative ease of scaling up to larger areas, and – sometimes — the ability to use general lures that attract a variety of insects. Some insects are attracted only, or primarily, to specific lures. Labor intensiveness (and expense) varies with how many traps must be deployed, whether the sites are easily accessible, difficulty extracting trapped insects, and the difficulty sorting the dead insects to find the species of interest.

A second approach is more labor-intensive and expensive, but it gives more information on the target species. This approach is to rear intercepted insect larvae in logs inside containers (to prevent escape) until they reach maturity and emerge. This approach facilitates determination of the species (it is difficult to identify larvae) … and allows an evaluation of feeding behavior – which translates into assessment of the damage caused to the tree.

The Canadian Food Inspection Agency (CFIA) began applying this survey method in 2006. CFIA collects logs from trees in declining health at high risk sites, such as industrial zones, current and historic landfills, and disposal facilities where large volumes of international wood packaging and dunnage are stored for extended periods of time. The logs are obtained from trees removed as part of municipal hazard tree removal programs. CFIA takes the logs to one of four research laboratories (in Toronto, Nova Scotia, Montreal, and North Vancouver), where they are placed in rearing chambers and allowed time to see what insects emerge. The logs are also dissected to reveal the type of damage caused by the insects – that is, determine whether insect was cause of tree mortality [Bullas-Appleton et al. 2014) .

The United States is applying the same approach, but less systematically.

APHIS developed a short-term project aimed at addressing two challenges: identifying larvae found in wood packaging to the species level (larvae intercepted at the border are often identified only to family); and gaining valuable information about the failure of currently required phytosanitary treatments as regards particular genera and species.

In a cooperative project begun in 2012, the DHS Bureau of Customs and Border Protection (CBP) collected live larvae of Cerambycidae and Buprestidae (and, since September of 2015, Siricidae), intercepted during inspection at initially six, later 11 U.S. ports.

mesh bags in which APHIS is rearing larvae obtained from wood packaging inspected by CBD at ports of entry
photo by USDA APHIS

These larvae were sent to an APHIS containment facility where many were reared to adults. Upon emergence, adult specimens were killed and identified by experts working for the National Identification Service. DNA barcodes of dead larvae and the reared adults were defined and compared and any new information was added to public genetic databases. These DNA barcodes have enhanced the capacity of anyone involved in pest interception and detection to rapidly identify larval stages. In 2017, APHIS determined that it had detected almost the full range of species that might be transported in wood packaging, and stopped funding the project.

As of June 2017, the APHIS project had received 1,289 intercepted wood borers (1,052 cerambycids, 192 buprestids and 45 siricids) from 45 countries (See Nadel et. al 2017). The extensive analysis of velvet longhorned beetle described in my previous blog link was greatly assisted by the resulting data.

Cerambycid larva which was part of the study
photo USDA APHIS

Years before the APHIS project, USDA Forest Service wanted to try applying rearing techniques to aid early detection of insects in the country. At first, the scientists asked residents of Washington, D.C. to identify street trees that appeared to be infested with pests. Those trees were then cut and sections placed in rearing containers to allow scientists to determine what was causing the problem (Harvard Science).

The project was transferred in 2015 to Boston and New York. The Boston location is an arboretum; the advantage of this site is that it has 1) a diversity of tree species; 2) trained staff; and 3) detailed records of most trees on-site (Harvard Science). Project scientists now accept material from stressed, diseased, or dying trees. This material is loaded into sealed barrels and allowed two years for insects to emerge. Since 2015, project scientists have examined 8,605 beetles comprising 223 species. These studies have resulted in 16 new state records, records of some Scolytinae that are rarely collected from traditional trapping methods; documentation of new host associations; and discovery of one previously undescribed species — Agrilus sp. 9895 (See DiGirolomo, Bohne and Dodds, 2019).

SOURCES

Bullas-Appleton, E., T. Kimoto, J.J. Turgeon. 2014. Discovery of Trichoferus campestris (Coleoptera: Cerambycidae) in Ontario, Canada and first host record in North America. Can. Entomol. 146: 111–116 (2014).

Marc DiGirolomo, Michael Bohne, Kevin Dodds. 2019. Presentation to the 19^th Annual Meeting of the Continental Dialogue on Non-Native Forest Insects and Diseases https://continentalforestdialogue.files.wordpress.com/2019/12/bohne.continentaldialogue1.pdf USFS – Durham, NH – 19^th Dialogue meeting

Haack, R. A. 2006. Exotic bark- and wood-boring Coleoptera in the United States: recent establishments and interceptions. Can. J. For. Res. 36: 269–288.

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

Krishnankutty, S.M., K. Bigsby, J. Hastings, Y. Takeuchi, Y. Wu, S.W. Lingafelter, H. Nadel, S.W. Myers, and A.M. Ray. 2020. Predicting Establishment Potential of an Invasive Wood-Boring Beetle, Trichoferus campestris (Coleoptera: Cerambycidae) in the United States. Annals of the Entomological Society of America, 113(2), 2020, 88-99. https://doi.org/10.1093/aesa/saz051

Nadel, H. S. Meyers, J. Molongoski, Y. Wu, S. Lingafelter, A. Ray, S. Krishnankutty, A. Taylor. 2017. Identification of Port Interceptions in Wood Packing Material Cumulative Progress Report, April 2012 – June 2017

Ray, A.M., J. Francese, Y. Zou, K. Watson, D.J Crook, and J.G. Millar. 2019. Isolation and identification of a male-produced aggregation sex pheromone for the velvet longhorned beetle, Trichoferus campestris. Scientific Reports 2019. 9:4459. https://doi.org/10.1038/s41598-019-41047-x

Posted by Faith Campbell

Have we dodged a bullet? (more like a burst of fire from a submachine gun)

Cerambycid larva detected in wood packaging
photo by Oregon Department of Agriculture

Many highly damaging wood-borers have been introduced to North America in wood packaging.

One woodborer, a beetle in the Cerambycidae, has been introduced multiple times to the United States — both before and after implementation of ISPM#15, the international regulations designed to stop such introductions. This is the velvet longhorned beetle (VLB) (Trichoferus (=Hesperophanes) campestris). Independent scientists have recently documented how VLB is introduced and where it is established.

I first blogged about the VLB three years ago. At that time, I asked why APHIS had not undertaken a quarantine and other actions to contain or eradicate the beetle, which was clearly established in an orchard in Utah (Wu et al. 2020; full source citations appear at the end of the blog). Now, the VLB is established in three states and has been detected in many more (details below).

It appears that the VLB will not cause significant damage. I hope this proves true, because it is certainly travelling here on a regular basis. While the most detailed study of the VLB’s potential impact in North America is not yet complete, early indications are that the beetle attacks mostly dying or dead trees.

A Widespread and Adaptable Pest

The VLB is native to China, Central Asia, Japan, Korea, Mongolia, and Russia. It has also been recorded in several European countries. The risk of introduction is broader, however. VLB has established throughout the Middle East and Europe, as well as parts of South and Central America. U.S. officials have intercepted live VLB individuals in shipments originating from these introduced populations, i.e., Brazil, Italy, Mexico, and Spain (Ray et al. 2019).

Wu et al. (2020) studied the genetic diversity of VLB specimens collected by in the United States by 1) trapping at several locations and 2) by testing those intercepted in wood packaging at U.S. ports. The scientists found high levels of diversity between and even within each limited geographic population. These results indicate that VLB has been introduced numerous times via the wood packaging pathway. They also found some evidence that introduced VLB populations might be expanding so it is important to understand pathways of spread within the country (Wu et al. 2020).

Where VLB is in the United States

The VLB is now officially considered to be established in Cook and DuPage counties, IL; Salt Lake County, UT; and Milwaukee, WI. [Krishnankutty et al. 2020).

However, adults have been detected in 26 counties in 13 additional states, plus Puerto Rico, since 1992. Since a trapping survey for woodborers began in 1999, this joint federal and state Cooperative Agricultural Pest Survey (CAPS) has trapped VLB in Colorado (2013), Illinois (2009), New Jersey (2007, 2013), New York (2014, 2016–2018), Ohio (2009, 2017–2019), Pennsylvania (2016), Rhode Island (2006), and Utah (2010, 2012–2019). (Krishnankutty et al. 2020). Also, Oregon detected VLB in 2019 (Oregon Department of Agriculture 2019).

Interceptions in Wood Packaging

The velvet longhorned beetle has been detected frequently in wood packaging since at least the middle 1980s (when APHIS began recording interceptions) (Haack 2006). (Haack’s study covered 1985-2000, before implementation of the International Standard on Phytosanitary Measures (ISPM) #15.)

APHIS’ official interception database listed 60 separate interceptions of VLB in the more recent ten plus-year period June 1997 – November 2017 – which overlaps pre- and post-implementation of ISPM#15. Eighty-eight percent of these interceptions were in wood packaging. Seven percent were in wood products. The remaining seven percent were in passenger baggage or unidentified products.

As has been the case generally since ISPM#15 was adopted, a high percentage — 65.4% — of the intercepted wood packaging during this period bore the mark certifying compliance with the ISPM#15 treatment requirements. Unsurprisingly, China was the origin of 81.6% of the intercepted shipments infested by pests (Krishnankutty et al. 2020).

In the most recent data studied, all from the period after implementation of ISPM#15 — 2012 – 2017, 28 VLB were found in analyses of a sample of wood packaging (Nadel et al. 2017). (I will discuss this study and other detection tools in a separate blog.)

In agreement with earlier findings, the most high-risk imports were determined to be wood packaging for stone, cement, ceramic tile, metal, machinery, manufactured wood products (furniture, decorative items, new pallets, etc.), and wood-processing facilities (Krishnankutty et al. 2020).

These findings largely confirm what we already know about the wood packaging pathway and high levels of non-compliance with ISPM#15 by Chinese shippers. What is APHIS going to do about this well-documented problem? APHIS certainly shouldn’t ignore these findings on the grounds that this particular wood-borer is less damaging than many others. Any chink in our phytosanitary programs that allows transport and entry of VLB can – does! – allow introduction of other woodborers.

The VLB also has been found in rustic furniture – often after the furniture has been sold to consumers. I discussed a 2016 example of this pathways in my February 2017 blog. Krishnankutty et al. (2020) suggest other possible pathways are wooden decorative items and nursery stock, particularly penjing (artificially dwarfed trees and shrubs).

Krishnankutty et al. (2020) note the importance of proper disposal of wood packaging once the cargo reaches its destination. Have any state phytosanitary officials enacted regulations targetting this source of invaders?

pallet “graveyard” – Photo by Anand Prasad, Davey Tree

The Risk to North America’s Forests Is Unknown

A climate-based model described in Krishnankutty et al. (2020) suggests that climate appears to be suitable for VLB across much of the continental United States, northern Mexico, and southern Canada. Only Florida, southern Texas, and high elevation and coastal regions of the western United States and Mexico states are unlikely to support the velvet longhorned beetle, based on climate. (The study did not consider whether host trees would be present.)

Asian and European sources list a broad host range consisting of at least 40 genera of conifers, hardwoods, and fruit trees (Krishnankutty et al. 2020). Still, as noted above, new studies seem to indicate a minimal impact on healthy trees in North America. Indeed, the principal Utah outbreak is in an orchard littered with pruned material.

With so many suitable hosts across so much of the country, the potential for damage is frightening.

Setting Priorities for Surveillance

The availability of data on both port interceptions and multiple detected outbreaks provides an opportunity to test procedures for carrying out early detection surveys. Improving the efficacy of early detection is critical since – as Wu et al. (2020) note – — the majority of infesting larvae would probably not be intercepted and would subsequently be transported to the cargo’s intended destinations. This is despite CBP’s best efforts to target inspection of wood packaging shipments based on shippers’ histories of non-compliance, targeting that I strongly support.

In response to this concern, Krishnankutty et al. (2020) analyzed pathways of introduction – 1) the types of imports associated with VLB-infested wood packaging, 2) ports where the beetle has been detected in recent years, plus 3) the presence and calculated probable volume of imports of types of commercial operations considered likely to transport the beetle. These included wholesale and retail sellers of products known to be risky and businesses involved with wood fuel processing, log hauling, logging, and milling of saw lumber (Krishnankutty et al. 2020).

They could test the value of this approach by comparing the calculated “intended destination counties” declared at import to actual detections of T. campestris. VLB was detected (by CAPS or other surveys) in either the same or a neighboring county for 40% of the intended destination counties.

This seems to be a high introduction rate; detections will probably rise now that a species-specific lure is available. What could this mean for the establishment rate? Is anyone going to repeat the comparisons to track such changes? Unfortunately, we lack sufficient data to compare the VLB establishment rate (whatever it turns out to be) to the rate for other wood-borers.

Focusing on their original intentions, Krishnankutty and colleagues considered the 40% correlation between intended destinations and VLB detections to be sufficiently rewarding to be one basis for setting priorities for surveys (Krishnankutty et al. 2020).

Krishnankutty et al. (2020) say that recognition of three established populations and widespread destinations of potentially infested wood packaging to climatically suitable areas points to the need to determine whether additional populations are already established – or might soon become so. I add this need is further supported by the frequent detections of low numbers of the VLB in at least seven other states (see above). They call for enhanced surveillance to determine where the VLB is.

Improved surveillance is now facilitated by Dr. Ann Ray’s identification of a specific pheromone that can be synthesized in a lab and used to lure VLB to traps. The pheromone is much more effective in attracting VLB than previous food-like lures used by CAPS as general-purpose attractants for wood-boring insects.APHIS had provided about $50,000 over four years from the Plant Pest and Disease Management and Disaster Prevention program (which receives funding through the Farm Bill) to Dr. Ray’s search for the species-specific pheromone.

what happens when detection fails –
dead champion green ash in Michigan

I will discuss detection efforts in a separate blog.

SOURCES

Haack, R. A. 2006. Exotic bark- and wood-boring Coleoptera in the United States: recent establishments and interceptions. Can. J. For. Res. 36: 269–288.

Krishnankutty, S.M., K. Bigsby, J. Hastings, Y. Takeuchi, Y. Wu, S.W. Lingafelter, H. Nadel, S.W. Myers, and A.M. Ray. 2020. Predicting Establishment Potential of an Invasive Wood-Boring Beetle, Trichoferus campestris (Coleoptera:) in the United States. Annals of the Entomological Society of America, XX(X), 2020, 1–12

Oregon Department of Agriculture, Plant Protection & Conservation Programs. 2019. Annual Report 2019.

Wu, Y., S.M. Krishnankutty, K.A. Vieira, B. Wang. 2020. Invasion of Trichoferus campestris (Coleoptera: Cerambycidae) into the United States characterized by high levels of genetic diversity and recurrent intros. Biological Invasions Volume 22, pages1309–1323(2020)

Posted by Faith Campbell

Hope for eastern hemlocks – IF funding can be obtained

eastern hemlocks in Great Smoky Mountains National Park

As we all know, eastern (Tsuga canadensis) and Carolina (T. caroliniana) hemlocks have suffered huge losses due primarily to the introduced hemlock woolly adelgid (Adelges tsugae – HWA). In New England, there has been more than a 60% decrease in total hemlock basal area since 1997 and a virtual absence of hemlock regeneration in HWA-infested areas. HWA continues to spread – most recently into western Michigan and Nova Scotia (all information, unless otherwise indicated, is from Kinahan et al. 2020; full citation at end of this blog). [However, Morin and Liebhold (2015) found that hemlock basal volume continued to increase for the first 20 years or so after invasion by the adelgid, due to ingrowth of immature hemlocks. See “results” in Morin et al., full citation at the end of the blog.]

This loss deprives us of a gorgeous tree … and unique habitats. Hemlock-dominated forests were characterized by deep shade, acidic and slowly decomposing soil, and a cool microclimate. They provided unique and critical habitat for many terrestrial and aquatic species.

A team of scientists based at the University of Rhode Island has carried out an experiment comparing cuttings from eastern hemlocks apparently resistant to HWA to susceptible ones. Matching sets of resistant and susceptible trees were planted at eight sites in seven states – Ithaca and Bronx, NY; Boston; southern CT; Lycoming County, PA; Thurmont, MD; southern WV; and Waynesville, NC. All plantings were within or adjacent to forests containing HWA-infested hemlocks.

After four years, 96% of the HWA-resistant hemlocks had survived, compared to 48% of the control plants. The HWA-resistant plants were 32% taller, put out 18% more lateral growth, had 20% longer drip lines, and were in 58% better condition. HWA was found on trees at only three out of the eight plots. HWA density on resistant eastern hemlocks was 35% lower than on HWA-susceptible hemlocks, although this difference was not statistically significant.

Trees in all eight plots were infested with elongate hemlock scale (Fiorinia externa – EHS), a second insect damaging hemlocks in eastern North America. However, the HWA-resistant hemlocks had EHS densities 60% lower than those of the controls.

Kinahan et al. note that identification and use of host tree populations’ potential for pest resistance has played a role in other programs managing non-native pests and pathogens, including Dutch elm disease and chestnut blight.

The same scientists note that significant effort has been put into biocontrol or insecticides for management of hemlock woolly adelgid, but without achieving the desired improvement of forest health. Attempts to cross eastern hemlocks with HWA-resistant hemlocks unfortunately produced no viable offspring. However, Kinahan et al. were inspired to explore possible genetic resistance within natural populations of eastern hemlocks by the 1) evidence of resistance in Asian and western hemlocks; 2) the different foliar terpene profiles in those species; and 3) the presence of apparently healthy mature hemlock trees growing in proximity to heavily infested trees.

They asked forest managers and other concerned groups to help locate stands with trees that were mature and apparently completely healthy, were located within HWA-devastated hemlock stands, and had not been chemically treated. They chose a small stand of eastern hemlocks growing within the Walpack Fish and Wildlife Management Area in northern New Jersey. This stand was called the “Bulletproof Stand”. They evaluated HWA resistance in five of these trees, then chose two for propagation and planting in the test.

New Jersey’s “bullet-proof stand” on the left
photo by Richard Casagrande

The trees were planted in September 2015. Due to funding gaps, they were not revisited for four years. Thus, Kinahan et al. re-evaluated the resistant and vulnerable trees in Autumn 2019 – with the results I reported above.

Does this study prove that clonal propagation of apparently resistant hemlocks is an effective strategy to restore the species?

It is not that simple.

The difference in survival and condition was striking, but the authors note several caveats:

1) they had not recorded pre-experiment data on plant height or other variables, so they cannot be certain that variation in initial plant height or dripline did not contribute to current treatment-level differences in these variables.

2) they cannot distinguish between the impacts of HWA and EHS on plant growth.

3) since they could not monitor the planting sites for four years, they cannot definitively link increased mortality of HWA-susceptible trees to higher pest densities. However, the lower pest densities and higher survival of HWA-resistant hemlocks are consistent with herbivore-driven tree mortality.

They also cannot assess the impact of other environmental stressors (drought, cold, etc.) on their results.

4) The small number of trees planted at each site prevented detailed site-level analyses.

The scientists conclude that their work is most appropriately viewed as a ‘proof of concept’ experiment highlighting the need for future research exploring how HWA-resistant eastern hemlocks might best be integrated into existing HWA management.

Unfortunately, the Rhode Island researchers report they cannot persuade the US Forest Service to support continuing this effort. Will these promising hints not result in action?

Kinahan et al. stress the importance of the reduced pest densities (both HWA and EHS) on the putatively resistant hemlocks. They think this might be a result of the higher terpene concentrations in the twigs and needles. Finally, they note that lower densities of sap-feeding herbivores may also indirectly provide protection against other consumers, including gypsy moth (Lymantria dispar) and hemlock looper (Lambdina fiscellaria).

SOURCE

Kinahan, I.G., G. Grandstaff, A. Russell, C.M. Rigsby, R.A. Casagrande, and E. L. Preisser. 2020. A four-year, seven-state reforestation trial with eastern hemlocks (Tsuga canadensis) resistant to hemlock woolly adelgid (Adelges tsugae). Forests 11: 312

Morin, R.S. and A.M. Liebhold. 2015. Invasions by two non-native insects alter regional forest species composition and successional trajectories. Forest Ecology and Management 341 (2015).

Posted by Faith Campbell

P.S. I have been working with colleagues to promote a more coordinated and well-funded program to combat non-native forest pests – including much greater reliance on identifying and breeding resistance to the pest. Visit here to see this effort.

Happy 14th Anniversary for Wood Packaging? Probably Not: Noncompliance, Fraud, and Missing Data

CBP inspectors examining pallet
CBP photo

This month is the 14^th anniversary of United States’ implementation of International Standard for Phytosanitary Measure (ISPM) #15 with the goal of reducing the risk of pest introduction via wood packaging.

Implementation of the international standard has apparently reduced the “approach rate” of pests in wood packaging, but not sufficiently (See my previous blog).

In this International Year of Plant Health (USDA/APHIS full citation at end of this blog), it is essential to understand how well the wood packaging program is working. Evaluating its current efficacy is especially important for protecting our forests. One key scientific society recognizes this: organizers of the Entomological Society of America’s Grand Challenges Summit in Orlando next November have chosen wood packaging as the theme.

Unfortunately, information essential to evaluate the efficacy of ISPM#15 – both worldwide and as implemented by USDA APHIS – is not yet available.

Our most up-to-date information on U.S. enforcement is from Kevin Harriger, Executive Director for the Agriculture Programs and Trade Liaison office, U.S. Customs and Border Protection (CBP). In his report to the annual meeting of the Continental Dialogue of Non-Native Forest Insects and Diseases in November 2019, he stated that over the past three years, CBP detected a regulated pest, on average, in 30% of wood packaging intercepted because it was not compliant with ISPM#15. Unfortunately, Mr. Harriger did not provide the actual number of shipments inspected or seized.

The absence of specific numbers means I cannot compare the 2019 findings to previous years. My calculation of Mr. Harriger’s data provided to the Dialogue in previous years showed that over the nine-year period Fiscal Years 2010 through 2018, CBP detected 9,500 consignments harboring a regulated pest. Ninety-seven percent of the shipments found to be infested with a pest bore the ISPM#15 mark. The wood packaging was from nearly all trading countries. CBP staff say the reason for this high proportion of pests in wood packaging is fraud.

A European study of imports of stone from China over the period 2013-2016 focused on a recognized high-risk commodity. Nevertheless, the Europeans reached the same finding: 97.5% of consignments that harbored pests bore the ISPM#15 mark. They concluded that the ISPM-15 mark was of little value in predicting whether harmful organisms were present (Eyre et al. 2018).

There is considerable dispute about which categories of packaging are most likely to be infested. The categories are pallets, crates, spools for cable, and dunnage (wood used to brace cargo and prevent it from shifting). Unfortunately, Mr. Harriger shed no light on that issue. He did report that 78% of non-compliant shipments over the last three years was in packaging associated with “miscellaneous cargo”, e.g., machinery, including electronics; metals; tile and decorative stone (such as marble or granite counter tops). This association has been true for decades (see Haack et al. 2014). Another 20% of the non-compliances were associated with fruit and vegetable cargoes. This probably reflects the combination of large volumes of produce imports from Mexico and that country’s poor record of complying with wood packaging requirements.

It has been reported that in recent years, CBP inspectors have repeatedly found pests in dunnage bearing the ISPM#15 mark and associated with “break bulk” cargo (goods that must be loaded individually; not transported in containers or in holds as with oil or grain). Ships that carry this sort of. Problems appear to be acute in Houston. While most of the criticism of non-compliant wood packaging refers to countries in Asia and the Americas, at least one of the Houston importers obtains its dunnage in Europe.

There is even a question about the volume in incoming goods. CBD says that approximately 13 million loaded containers enter the country every year by rail, truck, air, or sea. However, my calculation from U.S. Department of Transportation data (see reference) was that more than 22 million shipping containers entered the U.S. via maritime trade in 2017.

In 2017, CBP announced a new policy under which it will assess a penalty on each shipment in which the wood packaging does not comply with ISPM#15. Previously, no penalty was assessed until a specific importer had amassed five violations over a twelve-month period.

FY2019 was thus the second year under the new policy. I had hoped that Mr. Harriger would provide information on the number of penalties assessed and any indications that importers are strengthening their efforts to ensure that wood packaging complies. However, he did not.

He did report that CBP has expanded outreach to the trade. The goal is reducing all types of non-compliance – lack of documentation, pest presence, etc. in both wood packaging and shipping containers. Outreach includes awareness campaigns targetting trade, industry, affiliated associations, CBP employees, and international partners.

Still, authorities cannot know whether the actual “approach rate” of pests in wood packaging has changed in response to CBP’s strengthened enforcement because they lack a scientifically valid study. The most recent study – that reported in Haack et al. 2014 – relied on data up to 2009 – more than a decade ago. It indicated an approach rate of approximately 0.1% (Haack et al. 2014).

Unfortunately, USDA APHIS has not yet accepted researchers’ offer to update this study.

We do know that pests continue to be present in wood packaging 14 years after the U.S. put ISPM#15 into force.

I call for:

1) Determining the relative importance of possible causes of the persistent pest presence problem – fraud, accidental misapplication of treatments, or other failures of treatment;

2) Enhanced enforcement by APHIS as well as CBP;

3) Stepped up efforts to help US importers by APHIS and the Foreign Agricultural Service– by, e.g., providing information on which foreign suppliers of wood packaging and dunnage have good vs. poor records; conveying importers’ complaints about specific shipments to the exporting countries’ National Plant Protection Organizations (NPPOs), such as Departments of Agriculture;

4) Raising pressure on foreign NPPOs and the International Plant Protection Convention more generally to ascertain the specific reasons ISPM#15 is failing and to fix the problems identified.

Alernative Materials – Plastic!

I have also advocated for shifting at least some wood packaging – e.g., pallets and some crates – to alternative materials. For example, USDA APHIS could require exporters with bad records to use crates and pallets made from materials other than solid wood, e.g., plastic, metal, or oriented strand board. Or companies could make that shift themselves to avoid phytosanitary enforcement issues and penalties.

People recoil from the idea of using plastic and there are increasing concerns about the breakdown of plastics into tiny fragments, especially in water. But it’s also true that the world is drowning in plastic waste. Surely some of this could be recovered and made into crates and pallets with environmentally sound technology.

The Washington Post reported in November that an Israeli company is converting all kinds of trash – including food waste – into plastic, and molding that plastic into various items, including packing crates.

UBQ Materials takes in tons of rotting food, plastic bags, dirty paper, castoff bottles and containers, even broken toys. It then sorts, grinds, chops, shreds, cleans and heats it mess into first a slurry, then tiny pseudo-plastic pellets that can be made into everyday items like trays and packing crates.

Another Israeli company, Plasgad, uses plastic to make pallets, crates and other products.

Some who were skeptical now are more interested, including the president of the International Solid Waste Association and the chief executive of the Plastic Expert Group.

So – can we address three environmental problems at the same time – mountains of waste, methane gas releases contributing to climate change, and one (important) pathway for the movement of tree-killing pests?

SOURCES

Eyre, D., R. Macarthur, R.A. Haack, Y. Lu, and H. Krehan. 2018. Variation in Inspection Efficacy by Member States of SWPM Entering EU. Journal of Economic Entomology, 111(2), 2018, 707–715)

Harriger, K., Department of Homeland Security Bureau of Customs and Border Protection, presentation to the Continental Dialogue on Non-Native Forest Insects and Diseases, November 2017.

U.S. Department of Transportation, Maritime Administration, U.S. Waterborne Foreign Container Trade by U.S. Customs Ports (2000 – 2017) Imports in Twenty-Foot Equivalent Units (TEUs) – Loaded Containers Only.

U.S. Department of Agriculture, Press Release No. 0133.20, January 27, 2020

Posted by Faith Campbell

New Ambrosia Beetle in California – Threat to Oaks?

valley oak at Jack London State Park (24 miles from Calistoga)

In November, scientists discovered a new ambrosia beetle in symptomatic valley oaks (Quercus lobata) trees in Calistoga, Napa County. Some blue oaks (Q. douglasii) have also been attacked (Rabaglia et al. 2020). Trees associated with this outbreak showed wilting, defoliation, and broken branches. The infested wood was discolored, presumably by the fungus. The insect, Xyleborus monographus, is native to Europe.

Officials now know that this beetle is found throughout a 15-mile-long area in Napa and neighboring Lake and Sonoma counties. It has probably been there for several years (Rabaglia et al. 2020). One specimen of the beetle was trapped in Portland, Oregon in 2018, but no infestation was detected. The beetle has never been intercepted in California. Nor has it been found in traps designed to detect bark beetles which have been deployed in 11 counties – including several in the San Francisco Bay area but not including Napa or Sonoma.

Like all Xyleborus, adult females tunnel into tree’s trunks, carrying fungal spores in their mycangia (structures in the jaws in which microbes are harbored). Beetle larvae eat the fungi. Beetle reproduction is facilitated by sibling mating within the gallery and by the ability of unmated females to produce male offspring.

Sometimes the beetle’s associated fungi are pathogenic to living trees. One of the fungal species detected in the Calistoga infestation is Raffaelea montetyi, which is reported to be pathogenic to cork oak. The presence of this fungus had been reported in 2018, although the beetle species carrying it was not identified then. This is apparently the first report of this fungus in North America.

Known hosts of beetle X. monographus include European or Eurasian chestnut (Castanea sativa), beech (Fagus orientalis), and European and American oaks (including Q. lobata and Q. rubra). The possible effects of the beetle and associated fungi on other oak species is unknown. Oaks are acknowledged to be important components of forests and woodlands in California. Ambrosia beetles often attack stressed trees. Since California forests are increasingly frequently stressed by drought, fire, and other pests, they might be especially vulnerable.

The California Department of Food and Agriculture is currently seeking comments on what pest rank to assign the insect. The comment period closes on March 6^th and I encourage you to consider providing your views.

In their draft document ranking risk, state officials note that a proven host — Q. lobata — is widespread in California and the insect is probably capable of establishing over much of the state. The possible economic impact was described as possibly affecting production of oaks in California nurseries and triggering quarantines. (Does this mean CDFA expects impacts only on saplings? Is this realistic? CDFA made no mention of costs to urban areas for hazard tree management.)

The risk assessment notes that research by McPherson, et al. (2008) found that ambrosia beetles are attracted to oak trees already infected with sudden oak death (SOD) (Phytophthora ramorum). Therefore, X. monographus could have a synergistic impact with SOD on California oaks – which has already killed an estimated 1.9 to 3.3 million coast live and Shreve oaks.

SOURCE

Rabaglia, R.J. S.L. Smigh, P. Rurgman-Jones, M.F. Digirolomo, C. Ewing, and A. Eskalen. 2020. Establishment of a non-native xyleborine ambrosia beetle, Xyleborus monographus (Fabricius) (Coleoptera: Curculionidae: Scolytinae), new to North America in California. Zootaxa 478 (2): 269-276

Posted by Faith Campbell

Hawaiian Dry Forests – Glimmer of Hope for one tree, Alarm for a shrub

wiliwili flower
photo by Forrest and Kim Starr, courtesy of creative commons

Hawaii’s dryland forest is a highly endangered ecosystem. More than 90% of dry forests are already lost due to habitat destruction and the spread of invasive plant and animal species. However, a new publication documents some recovery of wiliwili trees from one major pest. At the same time, a new pest is spreading and killing naio, a critical dryland shrub. Both pests originated in countries that have rarely if ever been a source of U.S. pests. This is worrying because phytosanitary agencies have their hands full with imports from the usual sources. The role of California as a source of invasive species in Hawai`i has long deserved federal attention – but as far as I know has not received it.

Hope for Wiliwili Trees

The Hawaiian endemic wiliwili tree, Erythrina sandwicensis, occurs in lowland dry forests on all the major islands from sea level to 600 m. Wililwili is a dominant overstory tree in these habitats. (Unless otherwise noted, the principal source is Kaufman et al. in press – full citation at end of blog.)

The tree has been severely affected by the introduced Erythrina gall wasp, Quadrastichus erythrinae (EGW). The gall wasp was detected on Oahu in 2005 and quickly spread to the other Hawaiian islands.

Arrival of the EGW on Oahu was part of the insect’s rapid global range expansion. Originally from East Africa, it was first detected in the Mascarene Islands and Singapore in 2003. At the time, it was unknown to science. Within a few years it had spread across Asia, many Pacific islands (including Hawai`i), and to the Americas, including Florida in 2006, Brazil in 2014 (Culik 2014), and Mexico in 2017 (Palacios-Torres 2017). Although apparently restricted to the Erythrina genus as host, it has lots of opportunities. This genus has 116 species distributed across tropical and subtropical regions: 72 species in the Americas, 31 in Africa, and 12 in Asia.

The severe damage to wiliwili (and to non-native Erythrina trees planted in urban areas and as windbreaks) prompted Hawaiian officials to immediately initiate efforts to find a classical biological control agent. The process moved rapidly. A candidate – a parasitic wasp species new to science, Eurytoma erythrinae – was found in East Africa in 2006. Host specificity testing was carried out. Scientists quickly learned to rear the parasitic wasp in laboratories. Release of the biocontrol agent was approved in November 2008 – only three and a half years after the EGW was detected on Oahu.

The biocontrol agent’s impact was quickly apparent. Establishment was confirmed within 1–4 months at all release locations throughout Hawai`i. Reduced pest impacts to trees were detected within two years. By 2018, only 33% of the foliage was damaged on the majority of wiliwili trees. Damage to non-native Erythrina had also declined.

Results of Biocontrol Agent’s Release

The biocontrol agent’s efficacy in reducing EGW’s impacts on trees has been evaluated for 10 years after the agent’s release. Monitoring was conducted at sites on four of the six main islands. (The monitoring program and its findings are described in Kaufman et al. in press).

I wonder how many other biocontrol agents have been monitored so closely for such a long time? Shouldn’t they all be?

Given the uniqueness and importance of such long-term assessment, it is worth looking at the data in detail.

1) Foliar Damage and Tree Health

In 2008, before release of the biocontrol agent, more than 70% of young shoots in wiliwili trees that were inspected were severely infested. The damage rating of “severe” fell from about 80% of trees in 2008 to about 40% in 2011. About 20% of trees surveyed – at sites on all islands – had no gall damage.

By three years after release of the biocontrol agent (2011), mortality rates attributed to stress from the EGW infestation for trees in natural areas fell to 21%. Mortality rates for trees in botanical gardens was somewhat higher – 34%. Kaufman et al. proposed several possible reasons: a) lingering presence of systemic insecticides that might have harmed the biocontrol agents early in the releases; b) year-round sustenance for the EGW as a result of the i) presence of alternative hosts and ii) supplemental irrigation which maintained fresh foliage on the trees.

Less intensive monitoring occurred during 2013 – 2018. It showed continuing substantial suppression of EGW damage on Erythrina foliage, although levels varied among locations. Sites with the lowest precipitation and higher temperatures throughout the year had the slowest recovery of wiliwili. Still, trees are now producing vegetative flushes and healthier canopies during non-dormant periods.

2) Flower and Seed Damage

Successful reduction of infestations in flowers and seedpods was less immediate. Still, by 2011, seed-set had increased from less than 3% of trees setting and maturing seed, to almost 30% with mature seed. The proportion of trees bearing inflorescences also increased, with more than 60% of trees blooming three years after introduction of the biocontrol agent. There was also a slow but steady increase in seed production.

However, in 2019, it remains unclear how infestation of seedpods will affect germination and therefore future plant recruitment.

More worrying, little recruitment was observed over the 10 years. Hawaiian authorities have completed tests on, and are preparing a petition for release of, a second biocontrol agent, Aprostocitus nites. It is hoped that it will further suppress EGW in flowers and seedpods.

Still, poor recruitment is likely due to the combined impacts of multiple invasive species in native environments. A significant factor is a second insect pest – a bruchid, Specularius impressithorax – which can cause loss of more than 75% of the seed crop. I hope authorities are seeking methods to reduce this insect’s impacts.

The Hawaiian species group of the IUCN has given the wiliwili tree the Reed Book designation of “vulnerable”.

Worries for Naio

naio in bloom
photo by Forrest and Kim Starr, courtesy of creative commons

Naio (Myoporum sandwicense)is an integral component of native Hawaiian ecosystems, especially in dry forests, lowlands, and upland shrublands. However, it is also found in mesic and wet forest habitats. Naio is found on all of the main Hawaiian Islands at elevations ranging from sea level to 3000 m. The loss of this species would be not only a significant loss of native biological diversity but also a structural loss to native forest habitats.

The invasive non-native Myoporum thrips, Klambothrips myopori, was detected on the Big Island (Hawai‘i Island) in 2009 – four years after it was first detected on ornamental Myoporum species in California. At the time of the California detection, the species was unknown to science. It is now known that this species is native to Tasmania.

The thrips feeds on and causes galls on plants’ terminal growth and can eventually lead to death of the plant.

For close to a decade, the Myoporum thrips was restricted to the Big Island. It has now been found on Oahu (Wright pers. comm.) Alarmed by the high mortality of plants in California, in September 2010, the Hawaii Department of Lands and Natural Resources Division of Forestry and Wildlife and the University of Hawai‘i initiated efforts to determine spatial distribution, infestation rates, and overall tree health of naio populations on the Big Island. Monitoring took place at nine protected natural habitats for four years. This monitoring program was supported by the USFS Forest Health Protection program. (See also the chapter on naio by Kaufman et al. 2019 in Potter et al. 2019 – full citation at the end of this blog.)

naio damaged by thrips
photo by Leyla Kaufman, University of Hawaii

The monitoring confirmed that the myoporum thrips has spread and colonized natural habitats on the leeward side of Hawai`i Island. Infestation rates increased considerably at all sites over the duration of the four-year sampling period. Trees experiencing high infestation levels also showed branch dieback.

Medium-elevation sites (between 500–999 m) had the highest infestations and dieback: over 70% of the shoots had the worst damage.. At two sites, over 70% of the monitored trees have died.

Even though flowers and fruits were still seen at all sites, little to no plant recruitment was observed at these sites. Thus another plant species important in this endangered plant community is in decline.

Few management strategies are available for this pest. They include preventing spread to other islands and early detection followed by rapid application of pesticides.

Implications and Conclusions

The Erythrina gall wasp and myoporum thrips are only two of the thousands of invasive species established in Hawai`i. Island ecosystems, especially Hawai`i, are well recognized as especially vulnerable to invasive species. It has been estimated that on average 20 new arthropod species become established in Hawai`i every year.

East Africa and Tasmania are new sources for invasive species. Phytosanitary agencies need to adjust their targetting of high-risk imports to recognize this reality. Regarding the Hawaiian introduction of the thrips, there was probably made an intermediary stop in California – which is not unusual. (See also ohia rust.)

I applaud Hawaiian officials’ quick action to counter these pests. I wish their counterparts in other states did the same.

There are multiple threats to Hawaii’s dry forests, including habitat modification and fragmentation; wild fires; seed predation by rodents; predation on seeds, seedling, and saplings by introduced ungulates (e.g. feral goats, pigs and deer); competition with invasive weeds; and damage by invasive insect pests and diseases.

With so much of Hawaii’s dry forests already lost, the release of biocontrol agents targetting specific pests is only one element of a much-needed effort. Long-term protection of wiliwili and naio depends on greater efforts to reduce all threats and to stimulate natural regeneration of this ecosystem. These programs could include predator-proof fencing to keep out ungulates; baiting rodents and snails; and active collection. Breeding, and planting of threatened plant species in an effort to protect both the individual species and the habitat.

SOURCES

Culik, M.P., D. dos Santos Martins, J. Aires Ventura & V. Antonio Costa. The invasive gall wasp Quadrastichus erythrinae (Hymenoptera: Eulophidae) in South America: is classical biological control needed?

Kaufman, L.V., J. Yalemar, M.G. Wright. In press. Classical biological control of the erythrina gall wasp, Quadrastichus erythrinae, in Hawaii.: Conserving an endangered habitat. Biological Control. Vol. 142, March 2020

Palacios-Torres, R.E., J. Malpica-Pita, A.G. Bustamante-Ortiz, J. Valdez-Carrasco, A. Santos-Chávez, R. Vega-Muñoz and H. Vibrans-Lindemann. 2017. The Invasive Gall Wasp Quadrastichus erythrinae Kim in Mexico. Southwestern Entomologist.

Potter, K.M. B.L. Conkling. 2019. Forest Health Monitoring: National Status, Trends, and Analysis 2018. Forest Service Research & Development Southern Research Station General Technical Report SRS-239

Kaufman, L.V, E. Parsons, D. Zarders, C. King, and R. Hauff. 2019. CHAPTER 9. Monitoring Myoporum thrips, Klambothrips myopori (Thysanoptera: Phlaeothripidae), in Hawaii

Wright, Mark. 2005. Assistant Professor and Extension Specialist, University of Hawaii. Personal communication.

ISPM#15 – The Stamp is Not Effective as a Clue to Whether Wood Packaging is Pest-Free

For more than a decade, most countries in the world have required that crates, pallets, spools, and dunnage made from wood be treated in accordance with the requirements of the International Standard for Phytosanitary Protection (ISPM)#15 that this treatment be certified by applying an approved stamp to the wood. The goal of the program is to “reduce significantly the risk of introduction and spread of most quarantine pests that may be associated with that material.”

However, experience and studies in both the United States and Europe demonstrate that the ISPM#15 stamp is not a reliable indicator of whether the wood packaging is pest-free.

1) In the United States, over a period of nine years – Fiscal Years 2010 through 2018 – U.S. Customs and Border Protection (CBP) detected 9,500 consignments harboring a pest in a regulated taxonomic group. Of the shipments found with infested wood packaging, 97% bore the ISPM#15 mark (See Harriger reference at the end of the blog). The wood packaging was from nearly all trading countries. 2) In the past two years, CBP inspectors have repeatedly found pests in dunnage bearing the ISPM#15 mark – as reported by U.S. importers of “break bulk” cargo into Houston. While most of the criticism of non-compliant wood packaging refers to countries in Asia and the Americas, at least one of the Houston importers obtains its dunnage in Europe.

3) In Europe, a two-year intensive survey of wood packaging associated with shipments of stone from China to the 28 European Union countries over the period 2013-2016 again found that 97.5% of consignments found to harbor pests bore the ISPM#15 mark (Eyre et al. 2018). The scientists concluded that the ISPM-15 mark was of little value in predicting whether harmful organisms were present. (Eyre et al. 2018, p. 712)

As I have noted in previous blogs and policy briefs, the only in-depth study of the “approach rate” of pests in wood packaging, based on data which is now a decade old, found that 0.1% of incoming wood packaging transported a regulated pest (Haack et al. 2014). Given current trade volumes, as many as 17,650 containers per year (or 48 per day) transporting tree-killing insects might be entering the U.S. (My calculation of this estimate is explained in the blog on “risks of introduction” here.)

The Haack study excluded imports from Mexico, Canada, and China. The first and third countries have records of poor compliance with ISPM#15 requirements, so the “approach rate” for all incoming shipments might well have been higher.

The study of European imports focused on shipments of stone from China – which were deliberately chosen to represent types of imports presenting a high risk of transporting pests. Across Europe, over the four-year period, quarantine pests were detected in 0.9% of the consignments – somewhat higher than the U.S. number, as could be expected. However, there were large variations among participating countries’ findings. Austria and France found 6.95% of consignments inspected were infested, while half of European Union countries found none!

These differences demonstrate the importance of thorough inspections.

The data also indicate that the problem is not decreasing. Austria detected pests in nearly one-fifth (19.6%) of inspected shipments in 2016 – the final year of the study! However, during that same year, only 1.5% of wood packaging lacked the ISPM#15 mark.

So How Should the International Phytosanitary Community React to This Failure?

Data cited in numerous studies indicate that ISPM#15 has probably succeeded in reducing the presence of pests in wood packaging. This progress is good – but insufficient. Our forests need further reductions.

In the meantime, however, the international standard has demonstrably failed to provide a secure method to evaluate the pest risk associated with wood packaging accompanying any particular shipment. The presence of the stamp on pieces of wood packaging does not reliably show that the wood is pest-free. Officials need to determine why. Is it fraud? That would mean deliberately placing the stamp on wood that had not been treated, which U.S. CBP staffers think is occurring (Harriger). The European Union audit team that visited China also thought they detected instances of fraud. They concluded that “the current system of official controls in China does not adequately ensure that SWPM which forms part of consignments of goods exported to the EU is marked and treated according to ISPM No. 15” (Eyre et al. 2018, p. 713). On the other hand, the US importers in Houston say they are pressing their European suppliers to provide pest-free dunnage.

What more could we ask them to do to ensure that they are not receiving fraudulently marked materials?

Perhaps the problem has a different cause. Are the treatments themselves are less effective than expected? One APHIS study found that twice as many larvae reared from wood treated by methyl bromide fumigation survived to adulthood than larvae reared from heat-treated wood; the reason is unclear (Nadel et al. 2016). Unfortunately, it is apparently impractical to determine whether wood was heat treated by looking for changes in the chemical profile of the wood (Eyre et al. 2018).

Nor can we expect inspection of 100% of all risky consignments or detection of 100% of quarantine pests in those consignments that are inspected. Therefore, the European study authors concluded that inspection is best considered as a means of gathering evidence of risk and a deterrent rather than a means of completely preventing pest movement (Eyre et al. 2018).

The European study authors called for review of ISPM#15 as a control system and to investigate compliance at the source (Eyre et al. 2018 p. 714).

What is APHIS doing?

As I have noted previously – here and here – while U.S. CBP adopted a policy in 2017 under which it can penalize importers for each consignment not in compliance with ISPM#15, APHIS has not followed Custom’s lead on this. Instead, APHIS will apply a penalty only when an importer has accrued five violations over the period of a year. (The two agencies are acting under separate legal authorities.) This is yet another example of APHIS taking a less protective stance – as I described in earlier blogs.

Since Customs is now applying the letter of the law, the most useful step would probably be for APHIS (and the USDA Foreign Agriculture Service) to ramp up efforts to assist U.S. importers which are trying to comply. The importers are begging USDA to provide better information to them about foreign suppliers of wood packaging and dunnage. Which have good vs. poor records? USDA could also help importers trying to complain about specific shipments to the exporting countries’ National Plant Protection Organizations (NPPOs; departments of agriculture). In addition, APHIS could augment its pressure on foreign NPPOs and the International Plant Protection Convention more generally to ascertain the reasons ISPM#15 is failing and to fix the problems.

APHIS has not been idle. The North American Plant Protection Organization (including Canada and Mexico) has sponsored two workshops intended to educate NPPOs and exporters in Asia and the Americas about the standard’s requirements. APHIS is planning to address wood packaging in an international symposium organized under the auspices of the International Year of Plant Health in July 2020 – I will provide details when they become available.

APHIS is collaborating with the Entomological Society of America to host a workshop on wood packaging at the ESA annual meeting in November 2020 – I will provide details when they become available. The Continental Dialogue on Non-Native Forest Insects and Diseases plans to link its annual 2020 meeting to this workshop.

More immediately, the Continental Dialogue on Non-Native Forest Insects and Diseases will have presentations on the wood packaging issue at its annual meeting in just 11 days! in Cleveland

In preparation for the 2020 meetings, APHIS should fund more studies and audits of wood packaging to document the current efficacy of the standard (that is, the pest approach rate); remember, Haack’s study relied on data which are now a decade old. Not only has time passed … Both the standard and U.S. enforcement policies have changed since 2009.

Significance of the Wood Packaging Problems

The apparent failure of the ISPM#15 standard to provide a reliable means to certify treatment raises obvious issues regarding the risk of pest introductions. However, the implications are much broader.

The premise of the international phytosanitary system – the Agreement on the Application of Sanitary and Phytosanitary Standards (SPS Agreement) and International Plant Protection Convention (IPPC) – is that importing countries should rely on exporting countries to take the actions necessary to meet the importing countries’ plant health goals. The ISPM#15 experience casts doubt on this premise. The exporters are not reliably ensuring the cleanliness of their wood packaging. Worse, wood packaging is easier to treat than fruits, vegetables, and living plants (plants for planting). The latter commodities are much more easily damaged or killed by treatments than are boards or even logs – which are, after all, already dead! (A longer discussion of the SPS Agreement and IPPC is found in Chapter III of Fading Forests II, available here.

I hope that the international phytosanitary community will take advantage of the heightened attention and effort associated with the International Year of Plant Health in 2020 to re-examine all aspects of the current global phytosanitary system.

Posted by Faith Campbell

SOURCES

Eyre, D., R. Macarthur, R.A. Haack, Y. Lu, and H. Krehan. 2018. Variation in Inspection Efficacy by Member States of SWPM Entering EU. Journal of Economic Entomology, 111(2), 2018, 707–715)

Kevin Harriger, US CBP. Presentations to the annual meetings of the Continental Dialogue on Non-Native Forest Insects and Diseases over appropriate years. See, e.g., https://continentalforestdialogue.org/continental-dialogue-meeting-november-2018/

Nadel, N., S. Myers, J. Molongoski, Y. Wu, S. Linafelter, A. Ray S. Krishnankutty, and A. Taylor. 2016. Identificantion of Port Interceptions in Wood Packaging Material: Cumulative Progress Report, April 2012 – August 2016

https://www.joc.com/breakbulk/ispm-15-enforcement-leaves-shippers-no-good-nswers_20190717.htmlhttps://www.joc.com/breakbulk/enhanced-enforcement-ispm-15-costing-us-importers-millions_20190725.html

Recent Developments on Stopping Emerald Ash Borer

post-EAB ash forest in southern Michigan; photo by Nate Siebert, USFS

1) The Risks of Reliance on Biological Control

An article published lately indicates yet another complication that might undercut reliance on biocontrol to counter mortality of eastern ash populations caused by the emerald ash borer (EAB) (See my blogs from November — here and here) regarding APHIS’ proposal to eliminate EAB quarantines in favor of relying chiefly on biocontrol – with little data to back up the change.)

Olson and Rieske (full citation at the end of this blog) found that one of the principal biocontrol agents now in use, and on which APHIS proposes to rely, Tetrastichus planipennisi, does not parasitize EAB larvae living in white fringetree, Chionanthus virginicus. While this tree is a suboptimal host for EAB – lower numbers of the beetle survive – the white fringetree would support survival of some EAB – thereby undermining efficacy of the biocontrol program.

Since white fringetree grows a cross much of the eastern range of ash trees — from New York to Texas, as shown by the map posted here, the presence of this reservoir that can be exploited by EAB will challenge the efficacy of biocontrol.

Olson and Rieske believe the reason that T. planipennisi does not attack EAB living in white fringetree is that the fringetree’s wood is so dense that the wasp cannot detect the presence of EAB in the tree (T. planipennisi apparently relies on tactile and vibratory clues to find its prey).

2) A Possible New Biopesticide to Suppress EAB?

A presentation at the 81^st Northeastern Forest Pest Council by Mark Ardis of C.D.G. Environment described tests in the United States and Canada of methods for killing EAB by contaminating the beetles with the fungus Beauveria bassiana. The company is testing traps in which male beetles enter, become covered by fungal spores, then they fly out. The males not only become ill themselves, they also contaminate females during mating. Average overall beetle mortality from several test sites is 25%.

Given the terrible impact of the EAB invasions, I find it exciting to contemplate development of additional tools to be used in suppressing the beetles. However, I worry about possible impacts on non-target insects which might also be exposed to the fungal spores. A decade ago, David Wagner identified 21 species of insects that were specialists on Fraxinus, and said he expected additional species would also be associated with ash trees (full citation at end of blog). Mr. Ardis assured me that they had detected no insects other than EAB in the traps. I wish to see additional research on this issue.

The US Environmental Protection Agency would have to approve use of this biopesticide. I suggest that we all keep an eye on this process.

3) Citizen Scientists Searching for EAB- resistant “Lingering Ash”

Jonathan Rosenthal and Radka Wildova of the Ecosystem Research Institute have established a citizen science program to find ash trees that have survived the EAB invasion. These trees will become the foundation of efforts to breed more trees resistant to the EAB, which could be used to restore our forests.

The program is called “MaMa” – Monitoring and Managing Ash. So far, about 30 plots have been set up in New York, New Jersey, and Vermont where citizens are monitoring ash trees that have apparently survived the EAB invasion. The program seeks additional partners from other areas.

Searches for lingering ash must be strategically timed to ensure that the trees identified are truly resistant to EAB – not just late to become infested. But you can’t wait too long after the infestation wave has gone through an area, because the tree might die due to wind throw or human activity. Or, if a tree has just partial resistance (an important attribute for breeding!), it might eventually succumb. It is also imperative to avoid confusing stump sprouts with truly lingering ash. The conclusion: monitor the infestation and search for lingering trees two years after 95% of ash have been killed, or four years after 50% have been killed.

The MaMa program provides guidance, maps, electronic reporting systems … so you can help!

If you wish to participate – or to learn more – contact the program at monitoringAsh.org or 845-419-5229.

SOURCES

Olson, D.G. and L.K. Rieske. 2019. Host range expansion may provide enemy free space for the highly invasive emerald ash borer. Biol Invasions (2019) 21:625–635

Wagner, D.L. Emerald Ash Borer Threatens Ash-feeding Lepidoptera. 2007. News of the Lepidopterists’ Society. Volume 49, No. 1 (Spring 2007)

Posted by Faith Campbell

Spotted Lanternfly – Government Shut-Down Hampered Vital Effort at Crucial Time

spotted lanternfly; photo by Holly Raguza, Penn. Dept. of Agriculture

I last blogged about the spotted lanternfly (Lycorma delicatula) two years ago. At that time, this insect from Asia (where else?) was established in some portions of six counties in southeastern Pennsylvania. While its principal host is tree of heaven (Ailanthus altissima), it was thought to feed on a wide range of plants, especially during the early stages of its development. Apparent hosts included many of the U.S.’s major canopy and undertory forest trees, e.g., maples, birches, hickories, dogwoods, beech, ash, walnuts, tulip tree, tupelo, sycamore, poplar, oaks, willows, sassafras, basswood, and elms. The principal focus of concern, however, is the economic damage the lanternflies cause to grapes, apples and stone fruits (e.g., peaches, plums, cherries), hops, and other crops.

In the two years since my first blog, the spotted lanternfly has spread – both through apparent natural flight (assisted by wind) and through human transport of the egg masses and possibly adults. By autumn 2018, detections of one or a few adults – alive or dead – had been found in six additional states: Connecticut, Delaware, Maryland, New Jersey, New York, and Virginia.

spotted lanternfly quarantines (blue) & detection locations (yellow)
prepared by Cornell University

How many of these detections signal an outbreak? It is too early to know.

Impacts of the Government Shutdown

Unfortunately the federal government shutdown forced the cancellation of the annual USDA invasive species research meeting that occurs each January. The spotted lanternfly was to be the focus of six presentations. The most important of these was probably APHIS’ explanation of “where we are and where we are going.” The cancellation eliminated one of the most important opportunities for researchers to exchange information and ideas that could spur important insights. Equally important, the cancellation hampered communication of insights to practitioners trying to improve the pest’s management.

One pressing question was not on the meeting’s agenda, however. Would a much more aggressive and widespread response in 2014, when the lanternfly was first detected, have eradicated this initial outbreak? I have long thought that this question should be asked for every new pest program, so that we learn whether a too-cautious approach has doomed us to failure. However, authorities never address the issue – at least not in a public forum.

The shutdown also had an even more alarming impact. It interruptedaid by USDA APHIS and the Forest Service to states that should be actively trying to answer this question. Winter is the appropriate season to search for egg masses. It is also the season to plan for eradication projects.

spotted lanternfly egg mass; New York Department of Environmental Conservation

For the first several years, funding of studies of the lanternfly’s lifecycles and host preferences, research on possible biological or chemical treatments, and outreach and education came in the form of competitive grants under the auspices of the Farm Bill Section 10007. This funding totaled $5.5 million to Pennsylvania.

This commitment pales compared to Asian longhorned beetle or emerald ash borer h— which were also poorly known when they were first detected in the United States.

At the same time, the Pennsylvania infestation spread. It is now known to be established in portions of 13 counties and outbreaks were detected in neighboring Delaware and Virginia. h

This spread – and resulting political pressure – persuaded APHIS to multiply its engagement. A year ago, USDA made available $17.5 million in emergency funds from the Commodity Credit Corporation (that is, the funds are not subject to annual Congressional appropriation). APHIS said it would use the additional funds to expand its efforts to manage the outer perimeter of the infestation while the Pennsylvania Department of Agriculture would focus on the core infested area. APHIS said it would use existing (appropriated) resources to conduct surveys, and control measures if necessary, in Delaware, Maryland, New Jersey, New York and Virginia.

Summary of Latest Status in the Seven States

(see also the write-up here)

Pennsylvania: infestation established (quarantine declared) in portions of thirteen counties (Berks, Bucks, Carbon, Chester, Delaware, Lancaster, Lebanon, Lehigh, Monroe, Montgomery, Northampton, Philadelphia, Schuylkill). The quarantine regulates movement of any living stage of the insect brush, debris, bark, or yard waste; remodeling or construction waste; any tree parts including stumps and firewood; nursery stock; grape vines for decorative or propagative purposes; crated materials; and a range of outdoor household articles including lawn tractors, grills, grill and furniture covers, mobile homes, trucks, and tile or stone. See the regulation here: https://www.agriculture.pa.gov/Plants_Land_Water/PlantIndustry/Entomology/spotted_lanternfly/quarantine/Pages/default.aspx

Delaware: The state had been searching for the insect since the Pennsylvania outbreak was announced. After detection of a single adult female in New Castle County in November 2017, survey efforts and outreach to the public were intensified. Another dead adult spotted lanternfly was found in Dover, Delaware, in October 2018.

Virginia: infestation established (quarantine declared) in one county. Multiple live adults and egg cases of spotted lanternfly were confirmed in the town of Winchester, Virginia (Frederick County), in January 2018. As noted in my earlier blog, this region is important for apple and other orchard crops and near Virginia’s increasingly important wine region.

New Jersey: The New Jersey Department of Agriculture began surveying for lanternflies along the New Jersey-Pennsylvania border (the Delaware River) once the infestation was known. It found no lanternflies before 2018. In the summer, however, live nymphs were detected in two counties, Warren and Mercer. In response, the state quarantined both those counties and one located between them, Hunterdon. The state planned to continue surveillance in the immediate areas where the species has been found as well as along the Delaware River border in New Jersey.

New York: In 2017, a dead adult lanternfly was found in Delaware County.

State authorities expressed concern about possible transport of lanternflies from the Pennsylvania infested area.

In Autumn 2018, New York authorities confirmed several detections, including a single adult in Albany and a second single adult in Yates County. In response, the departments of Environmental Conservation and Agriculture and Marketing began extensive surveys throughout the area. Initially they found no additional lanternflies.

However, a live adult was later detected in Suffolk County (on Long Island).

Connecticut: a single dead adult was found lying on a driveway at a private residence in Farmington, CT, in October 2018. The homeowner was a state government employee educated about the insect. Relatives had recently visited from Pennsylvania (Victoria Smith, Connecticut Agricultural Experiment Station, pers. comm.). Searches found no other spotted lanternflies on the property. The state plans additional surveys in the area to confirm that no other spotted lanternflies are present.

Maryland: A single adult spotted lanternfly (male) was caught in a survey trap in the northeast corner of Cecil County near the border of Pennsylvania and Delaware (an area of known infestation) in October 2018. Because of the lateness of the season and sex of the insect, the Maryland Department of Agriculture does not believe that the lanternfly has established there.

All the affected states are encouraging citizens to report any suspicious finds.

Posted by Faith Campbell