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.
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.
prickly pear cacti in Big Bend National Park photo by Blake Trester, National Park Service
The cacti that are such important components of desert ecosystems across nearly 2 million square miles straddling the U.S.-Mexico border are under threat from non-native insects – as I have noted in earlier blogs. Of course, cacti are important in other ecoregions, too – I wrote recently about the columnar cacti in the dry forests of Puerto Rico.
Flat-padded prickly pear cacti of the genus Opuntia are threatened by the cactus moth, Cactoblastis cactorum.
In 1989, the cactus moth was found
in southern Florida, to which it had spread from the Caribbean islands (Simonson
2005). Recently, the moth was found to have spread west as far as the Galveston,
Texas, area and near I-10 in Columbus, Texas, about 75 miles west of central
Houston (Stephen Hight, pers. com.) Two
small outbreaks on islands off Mexico’s Caribbean coast have been eradicated.
In Florida, the cactus moth has
caused considerable harm to six native species of prickly pear, three of which
are listed by the state as threatened or endangered.
When the cactus moth reaches the
more arid regions of Texas, it is likely to spread throughout the desert
Southwest and into Mexico. In the American southwest, 31 Opuntia species are at risk; nine of them are endemic, one is endangered.
Mexico is the center of endemism for the Opuntia
genus. In Mexico, 54 Opuntia species
are at risk, 38 of which are endemic (Varone et al. 2019; full citation at end of this blog).
The
long-term effects of the cactus moth on these North American Opuntia are unknown because there may be
substantial variations in tolerance. The attacks observed in the Caribbean
islands have shown great variability in various cactus species’ vulnerability (Varone et al. 2019).
The Opuntia cacti
support a diversity of pollinators as well as deer, javalina (peccaries),
tortoises, and lizards. Prickly pears also shelter packrats and nesting birds (which
in turn are fed on by raptors, coyotes, and snakes), and plant seedlings. Their
roots hold highly erodible soils in place (Simonson 2005).
While scientists have been concerned about the possible impacts of the cactus moth since it was detected in Florida 30 years ago, a substantial response began only 15 years later. The U.S. Department of Agriculture began trying to slow the spread of the cactus moth in 2005 (Mengoni Goñalons et al. 2014), with a focus on surveys and monitoring, host (cactus) removal, and release of sterile males. This program was successful at slowing the moth’s spread and eradicating small outbreaks on offshore islands of Alabama, Mississippi, and Mexico.
Cactus moth damage to native cacti in Florida photo by Christine Miller, UF/IFAS
However,
the moth continued to spread west and the program never received an appropriation from Congress. The primary funding source was a US – Mexico
Bi-National Invasive Cactus Moth Abatement Program. Both countries contributed
funds to support the research and operational program to slow the spread in the
U.S. Funds were provided through USDA Animal and Plant Health and Inspection
Service (APHIS) and the Mexican Secretariat of Agriculture, Livestock, Rural
Development, Fisheries and Food (SEGARPA). Unfortunately,
funding was reduced by both entities and became inadequate to maintain the
Bi-National Program.
Therefore, in 2012, APHIS abandoned
its regional program and shifted the focus to biocontrol. This is now
considered the only viable control measure in the desert Southwest where vulnerable
cacti are numerous and grow close together. The biocontrol project has been funded
since 2012 through the Plant Pest and Disease Management and Disaster
Prevention program (which receives funding through the Farm Bill). It has
received a total of slightly more than $2
million over seven years. More than half the funds went to the quarantine
facility to support efforts to rear non-target hosts and verify the biocontrol
agent’s host specificity. About a quarter of the funds supported complementary
work of an Argentine team (both the cactus moth and the most promising
biocontrol agent are native to Argentina). Much smaller amounts have supported
U.S.-based scientists who have studied other aspects of the cactus moth’s
behavior and collected and identified the U.S. moths being tested for their
possible vulnerability to attack by a biocontrol wasp.
Here are
details of what these dedicated scientists achieved in just the past seven
years at the relatively low cost of roughly $2 million. Unfortunately, the project now faces a funding crisis and
we need to ensure they have the resources to finish their work.
Some
Specifics of the BioControl Program
After literature reviews, extensive collections,
and studies in the cactus moth’s native habitat in Argentina (Varone et al. 2015), a newly described wasp, Apanteles
opuntiarum (Mengoni Goñalons et al. 2014), has been determined to be host
specific on Argentine Cactoblastis species and the most promising
candidate for biocontrol. Wasps were collected in Argentina and sent to
establish a colony in a quarantine facility in Florida to enable host
specificity studies on North American Lepidoptera (Varone et al. 2015).
Quarantine
host specificity studies and development of rearing technology has not been straightforward. Initially, it was
difficult to achieve a balanced male/female ratio in the laboratory-bred generations;
this balance is required to maintain stable quarantine laboratory colonies for
host range testing. This difficulty was overcome. A second challenge was high
mortality of the cactus-feeding insects collected in the Southwest that were to
be test for vulnerability to the biocontrol wasp. These desert-dwellers don’t
do well in the humid, air-conditioned climate of the quarantine facility! For
these difficult-to-rear native insects, scientists developed a molecular
genetics method to detect whether eggs or larvae of the cactus moth parasitoid were
present inside test caterpillars after they were exposed to the wasps. For easy
to rear test insects, caterpillars are exposed to the wasps and reared to
adulthood. Host specificity tests have been conducted on at least five species
of native U.S. cactus-feeding caterpillars and 11 species of non-cactus-feeding
caterpillars (Srivastava
et al. 2019; Hight pers.comm.).
To
date there has been no instance of
parasitism by Apanteles opuntiarum on either lepidopteran non-target species or
non-cactus-feeding insects in the Florida quarantine or in field collections in
Argentina (Srivastava et al.
2019; Varone et al. 2015; Hight pers.comm.).
The scientists expected to complete host-specificity testing in the coming months, then submit a petition to APHIS requesting the release of the wasp as a biocontrol agent. Unfortunately, the project’s request for about $250,000 in the current year was not funded. This money would have funded completion of the host specificity testing, preparation of a petition to APHIS in support of release of the biocontrol agent into the environment, and preparation of the release plan.
Meanwhile,
what can we expect regarding the probable efficacy of the anticipated biocontrol
program?
Some
of the wasp’s behavioral traits are encouraging. The wasp is widely present in
the range of the cactus moth, and persisted in these areas over the years of
the study. The wasp can deposit multiple eggs with each “sting”. Multiple wasps
can oviposit into each cactus moth without detriment to the wasp offspring. Unmated wasp females
produce male offspring only, whereas mated females produce mixed offspring
genders. In the field, female wasps attack cactus moth larvae in a variety of
scenarios: they wait at plant access holes to sting larvae when they come
outside to defecate; they attack larvae when they are moving on the surface of
the pads; they can sting the youngest cactus moth larvae through the thin plant
wall of mined the pads; and they enter large access holes created by older
larvae and attack larger larvae. The wasps are attracted by the frass
(excrement) left on the outside of the cactus pads by cactus moth larvae (Varone
et al. 2020).
However, I wonder about the extent
to which the cactus moth is controlled by parasitoids in Argentina. Cactoblastis eggs are killed
primarily by being dislodged during weather events (rain and wind) and by
predation by ants. First instar larvae are killed primarily by the native Argentine
cactus plants’ own defenses – thick cuticles and release of sticky mucilage when
the young larvae chew holes into the pads where they enter and feed internally.
As larvae feed and develop inside the pads, the primary cause of mortality is
natural enemies.
Of
all the parasitoid species that attack C. cactorum, A. opuntiarum
is the most abundant and important. When the larvae reach their final state (6th
instars), they leave the pads and find pupation sites in plant litter near the
base of the plants. It is at this stage that the parasitism from A.
opuntiarum is detected in the younger larvae that were attacked while
feeding inside pads. As the moth larva begins to spin silk into which to
pupate, larvae of the wasp erupt through the skin of the caterpillar and pupate
within the silk spun by the moth. Predation by generalists (ants, spiders,
predatory beetles) accounted for high mortality of the unprotected last instar
and pupae (Varone et al. 2019).
Finally,
the cactus moth has three generations per year when feeding on O. stricta in the subtropical and tropical coastal areas of the Americas
and the Caribbean. In Argentina, on its native host, the moth completes
only two generations per year (Varone et
al. 2019).
How to
Get the Program Support Needed
Opuntia in Big Bend National Park Photo by Cookie Ballou, National Park Service
To date, no organized
constituency has advocated for protection of our cacti from non-native insect pests.
Perhaps now that the Cactoblastis
moth is in Texas, the threat it represents to our desert ecosystems will become
real to conservationists and they will join the struggle. The first step is to
resolve the funding crisis so that the agencies can complete testing of the biocontrol
agent and gain approval for its release. So now there is “something people can
do” – and I hope they will step forward.
I hope Americans are not actually indifferent
to the threat that many cacti in our deserts will be killed by non-native
insects. Many are key components of the ecosystems within premier National
Parks, and other protected areas. Cacti also are beautiful treasures in
botanical gardens. I hope conservationists will agree that these threats must
be countered, and will help to ensure
funding of the final stages of the biocontrol tests.
Sources
Mengoni Goñalons, C., L. Varone, G. Logarzo, M. Guala, M.
Rodriguero, S.D. Hight, and J.E. Carpenter. 2014. Geographical range & lab
studies on Apanteles opuntiarum (hymenoptera: braconiDae) in AR, a candidate
for BC of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America. Florida
Entomologist 97(4) December 2014
Srivastava, M., P. Srivastava, R. Karan, A. Jeyaprakash,
L. Whilby, E. Rohrig, A.C. Howe, S.D. Hight,
and L. Varone. 2019. Molecular detection method developed to track the
koinobiont larval parasitoid Apanteles opuntiarum (Hymenoptera: Braconidae) imported from Argentina to control Cactoblastis cactorum (Lepidoptera:
Pyralidae). Florida Entomologist 102(2): 329-335.
Varone, L., C.M. Goñalons, A.C. Faltlhauser, M.E. Guala,
D. Wolaver, M. Srivastava, and S.D. Hight. 2020. Effect of rearing Cactoblastis cactorum on an artificial
diet on the behavior of Apanteles
opuntiarum. Applied Entomology DOI: 10.1111/jen.12731.
Varone,
L., G. Logarzo, J.J. Martínez, F. Navarro, J.E. Carpenter, and S.D. Hight.
2015. Field host range of Apanteles
opuntiarum (Hymenoptera: Braconidae) in Argentina, a potential biocontrol
agent of Cactoblastis cactorum
(Lepidoptera: Pyralidae) in North America. Florida Entomologist — Volume 98,
No. 2 803
Varone, L., M.B. Aguirre, E. Lobos, D. Ruiz Pérez, S.D. Hight, F. Palottini, M. Guala, G.A. Logarzo. 2019. Causes of mortality at different stages of Cactoblastis cactorum in the native range. BioControl (2019) 64:249–261
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.
As happens every year, the Administration has proposed a budget for funding government programs in the next Fiscal Year (FY) – which begins on October 1, 2020 (FY2021). This proposal is not the final word. Congress will pass appropriations bills that will specify actual funding levels. NOW is the time for you to tell senators and representatives in Congress how much money you think agencies need to count tree-killing pests next year.
Pest programs most affected:
Sudden oak death (SOD):
Combination of goldspotted oak borer, laurel wilt, and thousand cankers disease
For the USFS, the Administration proposes alarming cuts.
Forest and Rangeland Research Program
FY18 F719 FY20 FY21 proposed
297,000,000 300,000,000 305,000,000 249,330,000
[In FYs 18 – 20, Forest Inventory & Analysis received $77 million of this total; the proposal for FY21 is $78.5 million. Under this proposal, inventory would receive more than 30% of all research funding!]
The Administration proposes to cut USFS R&D
overall by 25%. Also, it calls for closing the Pacific Southwest Research Station
in California.
These proposed cuts would come on top of severe reductions
over the past decade. Although the appropriation does not provide specific
spending figures for invasive species, funding for research conducted by the seven
research stations on ten non-native pests decreased from $10 million in FY2010
to just $2.5 million in FY2020 – a cut of more than 70%. The Service’s ability
to develop effective tools to manage the growing number of pests threatening
the health of the Nation’s forests is already crippled by the earlier cuts.
The proposal to close the Pacific Southwest Research Station is particularly unwise. This Station provides USFS’s crucially important expertise on both sudden oak death (SOD) and threats to Hawaiian forests, including rapid ʻōhiʻa death (ROD). These pathogens are already causing widespread and severe damage to forests in the region and leading experts work here.
USFS R&D must address two new threats associated
with sudden oak death:
need to better understand the possible impacts of the second, apparently more aggressive, genetic strain of the SOD pathogen now present in Oregon’s forests.
studies to determine which of the newly detected Phytophthora species found in Southeast Asia Link to blog and other regions might cause significant damage to America’s trees.
Other programs that USFS R&D should continue or
expand:
study the possible threat posed by the ambrosia beetle recently detected in Napa Valley of California.
understand the epidemiology and probable impacts of the recently detected beech leaf disease present from Ohio to Connecticut and possibly more widespread.
Forest Health Management Programs
Recent funding levels:
FY18 F719 FY20 FY21 proposed
96,500,000 98,000,000 100,000,000 73,636,000
The Forest Health Management (FHP)
Program supports federal agencies’ and partners’ efforts to prevent,
monitor, suppress, and eradicate insects,
diseases, and invasive plants. The White House proposes a $23 million cut, including a cut of $10
million to programs working on “cooperative lands” – all areas other than
federal lands. This proposed cut is short-sighted and worrisome. First, these forests
support a wide range of forest values. Second, non-native pests usually are usually
first introduced
in cities or suburbs – because they accompany imports destined for population centers. These newly arrived pests initially cause
enormous damage to urban forests. Counter-measures need to be initiated where
and when the pests arrive and their populations are low. We cannot afford to
wait for them to spread to national forest lands, when management will be
harder and more expensive.
Despite ever-rising numbers of non-native forest pests
over the past decade, funding for FHP work on Cooperative Lands has fallen by about
50%. Pest species suffering the largest cuts in recent FHP budgets are the
combination of gold spotted oak borer, thousand cankers disease, and laurel
wilt; Port-Orford cedar root disease, and threats to whitebark pines.
As I reported in a previous blog, an estimated 41% of forest biomass in the “lower 48” states is at risk from the 15 non-native pest species causing the greatest damage. Nevertheless, the Administration proposes to eliminate programs for several of the most hard-hit host tree species (redbay/laurel wilt, Port-Orford cedar, and whitebark pine) in FY2021. This proposal is contrary to priorities recommended through the CAPTURE project, which called for enhanced conservation efforts targetting these species specifically.
Also alarming is the cut to the informal “emerging pest” account. This valuable program funds projects targetting newly detected threats. Thus, in FY2019, FHP provided $125,000 to evaluate the probable impact of laurel wilt disease on sassafras, an important understory tree that grows throughout most of the Eastern Deciduous Forest. The program provided another $116,000 to support efforts to detect and understand beech leaf disease. Already, cuts in the overall FHP budget have necessitated cutting this valuable account from $1 million in FY19 to $750,000 in FY20 – and will probably result in additional cuts in FY21.
The budget proposes to cut funding to counter sudden oak death (SOD) Link to DMF by 15% — on top of a 52% cut since FY2018. SOD has killed an estimated 50 million trees from southern Oregon to central California. Not only does the pathogen continue to spread. Establishment of a second, more aggressive, genetic strain of the pathogen in the Oregon forest threatens to exacerbate the pathogen’s impact.
The forests of Hawai`i are facing their gravest threat
ever from a growing number of pests. FHP supported detection/monitoring of the
thrips attacking a dry forest tree, naio. There is a continuing need to address
threats to Hawaii’s most widespread tree, ʻōhiʻa lehua – which makes up 80%
of native forests – from the introduced “rapid ʻōhiʻa death”
fungi.
Finally, stakeholders will depend on leadership by the FHP program to manage spread of the emerald ash borer if the USDA Animal and Plant Health Inspection Service acts as expected and terminates the program under which it regulates movement of firewood, nursery stock, and other items that spread this pest. California and Oregon and other Western states are at greatest risk.
What You Can Do
Senators and representatives serving on the two
Interior Appropriations subcommittees will determine the final funding for USFS
programs.
Please ask them to support $303 million for USFS Research
and Development. Since the budget does not specify funding levels to be
allocated to non-native insects, pathogens, or other invasive species, ask for
“report language” instructing USFS to increase the funding for this vital
research area to five percent of the total research budget. Ask them also to
support maintaining the Pacific Southwest Research Station.
Also, ask them to support maintaining USFS Forest
Health and Management Programs at the FY20 level of $100 million in FY21. Ask
them to support $44 million for the “cooperative lands” program.
Members of the House Interior
Appropriations subcommittee
Betty
McCollum, Chair MN
Chellie Pingree ME
Derek Kilmer WA
José Serrano NY
Mike Quigley IL
Bonnie Watson Coleman NJ
Brenda Lawrence MI
David Joyce, Ranking Member OH
Mike Simpson ID
Chris Stewart UT
Mark Amodei NV
Members
of the Senate Interior Appropriations subcommittee
USDA Animal and Plant Health Inspection Service (APHIS)
Again, while the tree-killing pests
are usually introduced first in
cities or suburbs, the pests
don’t stay there. Instead, they proliferate and
spread … eventually threatening
forests across the continent.
APHIS has legal responsibility for preventing such pests’ entry, detecting newly introduced pests, and initiating eradication and containment programs intended to minimize the damage they cause. The risk of new introductions is tied to international trade. In 2017, an estimated 17,650 shipping containers (or 48 per day) infested by wood-boring insects entered the United States. Examples of such introductions include the Asian longhorned beetle, emerald ash borer, and several ambrosia beetles which carry the fungi now killing redbay and sassafras in the East, and sycamore and willow trees southern California. Other pests, such as gypsy moths and spotted lanternflies, are transported here as egg masses attached to hard-sided imports, containers, or ship superstructures. Yet more forest pests are brought here with or in imported plants. Two rapid ʻōhiʻa death (ROD) pathogens and beech leaf disease are among newly detected pests probably introduced this way.
APHIS
needs to be able to respond to these pests and to the others that will be
introduced in coming years. To do so, APHIS must have adequate funding for four
programs: “tree and wood pests” program at $60 million; “specialty crops”
program at $192 millon; “methods
development” at $28 million; and “detection” at $21 million.
The
“Tree and Wood Pests” account currently
supports
eradication and control efforts targeting only three insects: the
Asian longhorned beetle (ALB), emerald ash borer (EAB),
and gypsy moth. The program to eradicate the ALB has received about two-thirds of the funds — $40 million. It has succeeded
in eradicating 85% of the infestation in New York and some
of the outlying infestations in Ohio. There is
encouraging progress in Massachusetts, although at least one infested tree was
detected recently in a new town within the quarantine zone. Clearly, this
program must be maintained until final success is achieved everywhere.
The EAB program
has been funded at $7 million in recent years. APHIS has proposed to
terminate the EAB regulatory program. Program termination would greatly increase the risk that the EAB will
spread to the mountain and Pacific coast states, where both riparian woodlands
and urban forests would be severely damaged. Many stakeholders have urged APHIS
to continue
to regulate movement of firewood and other materials that facilitate the EAB’s spread.
The “Specialty Crops” program funds for APHIS’
regulation of nursery operations to prevent spread of the sudden
oak death pathogen. Were SOD to become established in the East,
it would threaten several oak species, sugar
maple, and black walnut. It is therefore alarming that in 2019, plants infected by the SOD
pathogen were shipped to 18 states. link to blog
APHIS must step up its regulatory efforts to prevent a repetition of this
disaster.
What You Can Do
Members of the Senate and House Agriculture
Appropriations Subcommittees will set final
funding levels for APHIS programs. Ask your members of Congressto support
maintaining the FY2020 funding levels for four APHIS programs: Tree
and Wood Pests, Specialty Crops, Methods Development, and “Detection
Funding”.
Also, ask them
to adopt report language urging APHIS to continue
regulating the EAB’s spread.
Members of
the House Agriculture Appropriations subcommittee
Sanford Bishop Jr., Chairman GA
Rosa DeLauro CT
Chellie Pingree ME
Mark Pocan WI
Barbara Lee Calif
13th (Oakland)
Betty McCollum MN
Henry Cuellar TX
Jeff Fortenberry, Ranking Member NE
Robert Aderholt AL
Andy Harris MD
John Moolenaar MI
Members of
the Senate Agriculture Appropriations subcommittee
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.
Fiscal Year 2020 began on October 1, 2019. In December Congress adopted funding bills (appropriations) for the full fiscal year – which ends next September.
APHIS
In
its Agriculture Appropriations bill, Congress is holding steady or increasing
funding for several APHIS programs that are important for addressing
tree-killing pests:
tree and wood pests program – $60 million (this is the same as FY2019, and $4 million above the Administration’s request);
Pest Detection – $27.4 million (this is same as FY219 and as the Administration’s request);
Methods development – $20.686 million (about the same as in FY2019 and the Administration’s request).
Specialty crops program – increased to $192.013 million. The accompanying report mentions two specific organisms as priorities – navel orangeworm and sudden oak death (apparently in response to an Oregon economic study and because Sen. Merkley is on the Appropriations Committee). This was above the $186 million in both the House and Senate bills and considerably above the Administration’s request of $176 million.
The Agriculture Appropriations bill reiterates helpful language from past laws authorizing the Secretary of Agriculture “to transfer … funds available to … the Department [of Agriculture] such sums as may be deemed necessary” to respond to disease or pest emergencies that threaten any segment of the U.S. agricultural production industry. However, for the past decade the Office of Management and Budget has prevented frequent use of this power. APHIS did receive emergency funds to address the spotted lanternfly in February 2018 (APHIS Press Release No. 0031.18)
(You might remember that in 2017-2018 I put forward
amendments to the Farm Bill that would have broadened APHIS’ access to
emergency funds. I sought especially to ensure that efforts to protect native
vegetation and urban trees would be eligible for funding. Unfortunately, this
amendment was not enacted.)
USDA Forest Service
The overall Research and Development program is funded
at $305 million – a few million above what I advocated for. Of this total, $77 million is allocated to the
Forest Inventory and Analysis program. In the past, research on invasive
species has received about 10% of the total research funds. The USFS has been
directed by Congress to restructure its research program. I will monitor any
changes and determine the implications for invasive species concerns.
USFS engagement on pest issues with other federal
agencies and state, local government, and private land managers is carried out
through the Forest Health Management program under the State and Private
Forestry division. While neither the appropriations legislation nor the
accompanying report provides any direction on forest health activities,
program staff report that funding for the overall program totals $104 million –
about $6 million more than in FY2019. Program work on federal lands is funded
at $66
million. However, $3 million has been deducted as part of a budget reform. After the deduction, this allocation is about $7 million above the
funding level for FY 2019. Program work on non-federal “cooperative” lands is funded at $44 million. Congress has instructed that $2 million of this total be given to the eastern
states’ forest health monitoring cooperative. The total “cooperative” lands allocation is
$2 million above the FY2019 allocation.
Conclusion
I am very pleased by Congress maintaining or
increasing funds for APHIS’ forestry programs. I am somewhat concerned by the pressure
to reform USFS programs. I worry especially about the increasing focus on
managing pests on federal lands compared to non-federal lands because nearly
all damaging invasions begin on non-federal lands.
ash tree killed by emerald ash borer Ann Arbor, MI photo provided courtesy of former mayor John Hieftje
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.
The National Park Service has a legal mandate to manage lands and waters under its jurisdiction so as to “preserve unimpaired” their natural and cultural resources (NPS Organic Act 54 U.S.C. § 100101, et seq.) Invasive species undermine efforts to achieve that mission. In 2000, the NPS adopted a program to coordinate management of invasive plants. It’s not as effective as needed – see the strategic plan.
However, only recently has NPS begun trying to prioritize and coordinate programs targetting the many animals and animal diseases which threaten Park resources. These organisms range from emerald ash borer and quagga mussels; to pythons, goats, and pigs; to diseases such as white nose syndrome of bats and avian malaria in Hawai`i.
In 2017, NPS released an internal study of the pervasive threat to Park resources posed by invasive animals and discussed steps to overcome barriers to more effective responses (Redford et al., 2017; full citation at end of this blog). The Chief of the Biological Resources Division initiated this report by asking a Science Panel to evaluate the extent of the invasive animal problem, assess management needs, review best practices, and assess potential models that could serve as a service-wide organizational framework. The report was to pay particular attention to innovative and creative approaches including, but not limited to, new genomic tools. I summarized the Panel’s findings and conclusions in a blog when its report appeared in 2017.
Significantly, the
Panel’s final report states that “a general record of failure to control
invasive species across the system” was caused principally by a lack of support
for invasive species programs from NPS leadership.
This
report has now appeared in the form of a peer-reviewed article in the journal Biological Invasions by Dayer et al. 2019 (full citation at end of
this blog). Although nine of the ten authors are the same on both reports there
are substantive differences in content. For example, the journal article
reiterates the principal findings and conclusions of the Panel’s final report,
but in less blunt language.
What’s Been Watered
Down
The
toning down is seen clearly in the statements some of the panel’s six key
findings.
Finding
#1
The panel’s report says: invasive animals pose a significant threat to
the cultural and natural values and the infrastructure of U.S. national parks.
To date, the NPS has not effectively addressed the threat they pose.
Dayer et al. says: the ubiquitous presence of invasive animals in parks
undermines the NPS mission.
Finding
#2
The panel’s report says: managing
invasive animals will require action starting at the highest levels, engaging
all levels of NPS management, and will require changes in NPS culture and
capacity.
Dayer et al. says: coordinated action is required to meet the challenge.
Finding
#4
The panel’s report states: effective
management of invasive animals will require stakeholder engagement, education,
and behavior change.
Dayer et al. says: public engagement, cooperation and support is [sic]
critical.
Wording
of the other three “key findings” was also changed, but these changes are less
substantive.
Drayer
et al. also avoid the word “failure”
in describing the current status of NPS” efforts to manage invasive animal
species. Instead, these authors conclude that the invasive species threat “is
of sufficient magnitude and urgency that it would be appropriate for the NPS to
formally declare invasive animals as a service-wide priority.”
Where the
Documents Agree – Sort of
Both
the Panel’s report and Dayer et al.
state that invasive animal threats are under-prioritized and under-funded. They
say that addressing this challenge must begin at the highest levels within the
NPS, engage all levels of management, and will require investments from the NPS
leadership. Even within individual parks,
they acknowledge that staffs struggle to communicate the importance of invasive
animal control efforts to their park leadership, especially given competition with
other concerns that appear to be more urgent. And they admit that parks also
lack staff capacity in both numbers and expertise.
Also,
both the Panel’s report and Dayer et al.
urge the NPS to acknowledge formally that invasive animals represent a crisis
on par with each of the three major crises that drove Service-wide change in
the past: over-abundance of ungulates due to predator control; Yellowstone fire
crisis (which led to new wildfire awareness in the country); and recognition of
the importance of climate change.
The
Panel suggested ways to update NPS’ culture and capacity: providing incentives
for staff to (1) address long-term threats (not just “urgent” ones) and (2) put
time and effort into coordinating with potential partners, including other park
units, agencies at all levels of government, non-governmental organizations,
private landowners, and economic entities. Dayer et al. mention these barriers but does not directly mention
changing incentives as one way to overcome them.
Both
the Panel’s report and Dayer et al.
suggest integrating invasive animal threats and management into long-range
planning goals for natural and cultural landscapes and day-to-day operations of
parks and relevant technical programs (e.g., Biological Resources Division,
Water Resources Division, and Inventory and Monitoring Division).
What is Missing
from the Journal Publication
The
Panel’s final report noted the need for increased funding. It said that such
funding would need to be both consistent and sufficiently flexible to allow
parks to respond to time-sensitive management issues. It proposes several
approaches. These include incorporating some invasive species control programs
(e.g., for weeds and wood borers)
into infrastructure maintenance budgets; adopting invasive species as
fundraising challenges for non-governmental partners (e.g., “Friends of Park” and the National Park Foundation); and
adopting invasive species as a priority threat. Dayer et al. do not discuss funding issues.
The final internal report envisioned the
NPS becoming a leader on the invasive species issue by 1) testing emerging best
management practices, and 2) educating visitors on the serious threat that
invasive species pose to parks’ biodiversity. As part of this process, the
authors suggest that the NPS also take the lead in countering invasive species
denialism. Dayer et al. do not mention the issue of invasive species deniers.
Common Ground:
Status of Invasive Animals in the Parks
The
Panel’s report and Dayer et al. describe
the current situation similarly:
More than half of the National parks that responded to the internal survey (245 of the 326 parks) reported problems associated with one or more invasive animal species.
The total number of species recorded was 331. This is considered to be an underestimate since staffs often lack the ability to thoroughly survey their parks – especially for invertebrates.
Invasive species threats to Parks’ resources have been recognized for nearly 100 years. The original report notes that 155 parks reported the presence of one or more exotic vertebrate species in 1977. At that time, exotic animals were the fourth most commonly reported source of threats. In 1991, parks identified 200 unfunded projects to address exotic species, costing almost $30 million.
Only a small percentage of non-native animal invasions are under active management. Dayer et al. stated that 23% have management plans at the park unit level, and only 11% are reported as being ‘‘under control”.
Individual parks have effective programs targetting specific bioinvaders (examples are described in Redford et al; a brief summary of these efforts is provided in my previous blog.
Common Ground on
Some Solutions
The
report and Dayer et al. promote the
same steps to improve invasive animal management across the Service. Both note
that the NPS is adopting formal decision support tactics to update and
strengthen natural resource management across the board. More specific steps include
establishing
a coordination mechanism that enables ongoing and timely information sharing.
mainstreaming
invasive species issue across the NPS branches or creating a cross-cutting IAS
initiative among the Biological Resources Division, Water Resources Division,
Inventory and Monitoring Division, Climate Change Response Program, and the
regional offices.
While
both documents call on the NPS to develop and test emerging technologies, the
Panel’s final report is more detailed,
providing, in Table 5, a list of several areas of special interest, including
remotely triggered traps, species-specific toxicants, toxicant delivery
systems, drones, environmental DNA, and sterile-male releases. Dayer et al. mention eDNA and metabarcoding
for ED/RR, biocontrol, and gene drives to control invasive pathogens. (Neither
document discusses possible concerns regarding use of CRISPR and other
gene-altering technologies, other than to say there would be public concerns that
would need to be addressed.)
Both
documents note the necessity of working with resource managers beyond park
boundaries to detect and manage species before they arrive in parks. They note
that developing and operationalizing such partnerships requires time and
resources. Furthermore, invasive species prevention, eradication, and
containment programs can be effective only with public support. They suggest
strengthening NPS’ highly regarded public outreach and interpretation program
to build such support, including through the use of citizen scientists.
The
Panel’s final report said that the NPS should recognize that the condition of
the ecosystem is the objective of efforts.
Its authors recognized that achieving this goal might require
reconsidering how ecosystem management is organized within NPS so interacting
stressors (e.g., fire) and management
levers (e.g., pest eradication/suppression, prescribed fire) would be addressed.
For this, the NPS would need to create a focused capacity to address the
pressing issue of invasive animals in such a way that fosters integrated
resource management within parks, focusing on fundamental values of ecosystem
states, and not eradication targets. Dayer et
al. called for the same changes without specifically labelling “condition
of the ecosystem” as the goal.
Publication of
Dayer et al. prompted me to find out
what progress the NPS has made in responding to the “key findings” in the
Panel’s final report (neither publication calls them “recommendations”).
The
National Park Service has acted on the recommendation to appoint an “invasive
animal coordinator” within the Biological Resources Division. That person is Jennifer Sieracki. However, I wonder whether a person located in BRD is of sufficient stature to
influence agency policy across all divisions. It is not clear whether there is active
coordination with the national-level invasive plant coordinator.
Dr.
Sieriaki responded to my query by noting the following new efforts 1) to
improve outreach to partners and
the public, and 2) to expand formal and informal partnerships with local,
state, federal and tribal entities and local communities near parks.
NPS should soon finalize
two formal partnerships with other agencies and organizations for outreach and
management of invasive animal species.
NPS is working with
researchers at the US Geological Survey to expand an existing modeling tool for
identifying potential suitable habitat for invasive plant species to include
invasive insects. This will help staff focus on the most likely locations for
introductions and thus assist with early detection and control.
NPS has created a
Community of Practice so NPS employees can seek each other’s advice on addressing
invasive animal issues. A workshop of regional invasive species coordinators is
planned for the coming months to guide direction of the service-wide program
and identify other top priorities. (Seriacki pers. comm.)
I also wonder whether the NPS can achieve the top-level coordination and outreach to the public called for by both reports while complying with the terms of Public Law 116-9 – the John N. Dingle Jr. Conservation, Management, and Recreation Act, which was enacted a year ago. Title VII, Section 10(i) of this law limits spending to carry out invasive species program management and oversight to 10% of appropriated funds. Less than 15% may be spent on investigations (research), development activities, and outreach and public awareness efforts (Section 10(h)). The law does allow spending for investigations regarding methods for early detection and rapid response, prevention, control, or management; as well as inspections and interception or confiscation of invasive species to prevent in-park introductions.
For more information, see my previous criticism of NPS failure to address invasive species issues here.
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.
See also my earlier discussion of the new legislation here.
SOURCES
Dayer,
A.A., K.H. Redford, K.J. Campbell, C.R. Dickman, R.S. Epanchin-Niell, E.D.
Grosholz, D.E. Hallac, E.F. Leslie, L.A. Richardson, M.W. Schwartz. 2019. The
unaddressed threat of invasive animals in U.S. National Parks. Biol Invasions
Redford,
K.H., K. Campbell, A. Dayer, C. Dickman, R. Epanchin-Niell, T. Grosholz, D.
Hallac, L. Richardson, M. Schwartz. 2017. Invasive animals in U. S. National Parks:
By a science panel. Natural Resource Report NPS/NRSS/BRD/NRR—2017/1564. NPS,
Fort Collins, Colorado. Commissioned by the NPS Chief of Biological Resources
Division. https://irma.nps.gov/DataStore/DownloadFile/594922
Jennifer Sieracki, Invasive Animal Coordinator,
Biological Resources Division, National Park Service
redbay in Georgia killed by laurel wilt photo by Scott Cameron
In August I posted a blog summarizing information on pest introductions and impacts gleaned over my nearly 30 years of engagement. Already, I need to post an update, with an alarming estimate of introduced pests’ impacts across the continent.
Fei
et al. 2019 (see the full citation is
at the end of this blog) estimate that the
15 most damaging introduced species threaten 41.1% of the total live forest
biomass in the 48 conterminous states.
In
fact, this might be an underestimate
of the pests’ impacts on biomass loss. Fei et
al. (2019) note several limitations in their data that might result in such
an underestimate. These include:
1)
Mortality rates – and impacts – may increase over several decades following the
initial invasion.
2)
For pests already established throughout nearly all their potential ranges,
pest-induced biomass loss could be substantially underestimated because most of
their hosts died long ago, before the FIA data began to be collected. Consequently,
the actual loss of these tree species from the forest is much greater than has
been measured by the study’s methods.
3)
Mortality rates vary among species and regions, which might introduce errors.
They cite European gypsy moth, in which relatively small areas of heightened
mortality due to repeated defoliations are swamped by lower mortality rates
across the chosen measurement area.
4)
They considered only tree mortality, not crown or root dieback or reductions in
tree growth.
5)
They did not estimate carbon release to the forest floor as a result of
defoliation.
6)
Pest-related mortality rates may be underestimated due to salvage – although
the authors did not observe evidence of substantial salvage efforts for most of
these pests.
7)
The data did not include losses from urban tree mortality.
Fei
et al. estimate that more than 450 pests
are established in the 48 conterminous states. This study excluded pests
attacking palms; trees on U.S. Pacific and Caribbean islands; and pests native
to portions of North America that are causing severe damage in naïve hosts – e.g., goldspotted oak borer. I did
include the latter groups in my slightly larger estimate laid out in my August
blog.
Fei
et al. base their analysis on 83 of
the introduced pest species considered to cause substantial effects on tree
health and productivity and sometimes extensive tree mortality. (In my August
blog, I described findings by another study by Guo et al (2019) that counted 91 species in that category.)
Fei et al. build on studies by a group of USDA Forest Service (USFS) scientists that I described in an earlier blog.
This team found that, nation-wide, non-native forest pests are causing an approximate 5% increase in total annual mortality by tree volume. They based their studies on analysis of 92,978 long-term plots maintained by the USDA Forest Inventory and Analysis program.
As
noted above, the article cannot capture the full range of mortality in species
affected by pests introduced decades ago. Chestnut blight, white pine blister
rust, Port-Orford-Cedar root disease, beech bark disease, butternut canker,
dogwood anthracnose, and European gypsy moths had all killed millions of trees
before the USFS forest inventory plots were established. Fei et al. do form a solid basis for measuring some of the current
impacts and projecting future ones.
The
focus of the new article is on the amount of carbon being transferred from live
biomass to dead organic matter as a result of the increased mortality caused by
the 15 species with the highest impacts. This is arguably a more quantifiable
measure of pests’ impacts than others’ approaches. Here, I focus more narrowly on the
documentation of exacerbated mortality as measured by the loss of biomass. Added
together, these 15 species have caused an additional (i.e., above background levels) tree mortality rate of 5.53 TgC per
year [defined as terragrams of carbon]. This
estimate of annual conversion of live biomass to dead wood is similar in
magnitude to that attributed to fire (5.4 to 14.2 TgC per year) (Fei et al. 2019). Yet the fire threat gets
much more attention – for both prevention and management.
It
is important to remember that conversion of living biomass to dead wood does
not result in an immediate release of carbon to the atmosphere. Atmospheric releases
take place through decomposition which is both gradual and takes place at
varying rates. Some of the carbon will remain in the soil. And, over time, some
of the carbon storage capacity will be restored by compensatory growth in
unaffected trees and the recruitment of new regeneration – although this faster
growth is delayed by as much as two or more decades after pest invasions begin
(Fei et al. 2019).
American elm being killed by “Dutch” elm disease photo by Cheryl Kaiser, University of Kentucky; bugwood.org
The 15 species of introduced pests used in this analysis
are laurel
wilt disease, chestnut blight, butternut canker, dogwood anthracnose, emerald
ash borer (EAB), Dutch elm disease, red pine scale, beech bark disease, hemlock
woolly adelgid, balsam woolly adelgid, European gypsy moth, white pine blister
rust, green spruce aphid, sudden oak death, and Port-Orford cedar root disease.
Of these, the highest elevation in biomass loss – as measured by FIA plot data
– was caused by EAB, Dutch elm disease, beech bark disease, and hemlock woolly
adelgid. We know that elms and beech, at least, began dying decades before the
FIA data began to be collected. So the reported mortality rates are an
underestimate. This is especially true because beech mortality is highest in
the first decade after invasion by beech bark disease.
Annual levels of biomass loss are virtually certain to increase. First, pests will spread to new host ranges and infestations in already-invaded ranges will intensify. As a result, substantial amounts of the hosts’ biomass are at risk of exacerbated mortality. As I noted at the top of the blog, the total amount of host biomass at risk from these 15 species is estimated to be 5,197 TgC – or 41.1% of the total live forest biomass in the 48 conterminous states. Further exacerbating future losses is the likelihood that additional pests will be introduced. I would add that pests not included in this analysis – e.g., polyphagous and Kuroshio shot hole borers and possibly the spotted lanternfly – are also likely to contribute to losses of live forest biomass.
Fei
et al. (2019) did not attempt to
determine the economic value of this biomass loss or to address other types of
losses to ecosystem services.
Remember that a separate set of studies reported by Potter et al. (2019) (the CAPTURE project) also relied on data from the FIA plots to evaluate the impact of introduced pests. These studies focused on identifying the host species at greatest risk rather than highest-impact pests or biomass loss. I find it reassuring that the Fei and Potter studies – using different approaches – resulted in very similar species rankings. See my discussion of the Potter studies here.
Together, the teams led by Potter and Fei set clear priorities for addressing the threats from non-native pests. What we need now is action! See my recommendations in my recent “solutions” blog.
U.S. Capitol – inform your representatives that you want action to protect trees!
SOURCES
Fei,
S., R.S. Morin, C.M. Oswalt, and A.M. 2019. Biomass losses resulting from
insect and disease invasions in United States forests
Potter,
K.M., M.E. Escanferla, R.M. Jetton, and G. Man. 2019a. Important Insect and
Disease Threats to United States Tree Species
and Geographic Patterns of Their Potential Impacts. Forests. 2019 10 304.
Potter,
K.M., M.E. Escanferla, R.M. Jetton, G. Man, and B.S. Crane. 2019b. Prioritizing
the conservation needs of United States tree species: Evaluating vulnerability
to forest insect and disease threats. Global Ecology and Conservation. (2019)
Fiscal
Year 2020 began on 1 October. Congress has not yet passed funding bills
(appropriations) for the full year. Agencies are operating now on a short-term
continuing resolution which expires on November 21st. Meanwhile,
representatives of the House and Senate will meet to reconcile the differences
between the two bodies’ appropriations bills in hope that a year-long bill can
be finalized by that time.
(Disagreement
between President Trump and the Congress about funding for the border wall
might prevent adoption of full-year appropriations bills and lead to another
government shutdown.)
I
report here the differences between House and Senate bills funding the USDA
APHIS and Forest Service programs that are vital to addressing non-native
forest pests.
APHIS
Over
the years, I have complained that inadequate funding is a major cause of
shortfalls in APHIS’ efforts to detect new invasions by tree-killing pests and to
respond to those invasions in effective ways.
While
funding levels are still too low, at least Congress is holding funding steady
for APHIS for Fiscal Year 2020 (which began three weeks ago, on October 1st).
Both House and Senate bills maintain funding for two crucial programs at the
FY19 levels:
“tree
and wood pests” program – $60 million (this matches the FY19 level; it is $4
million above the funding provided in previous years); and
“Pest
Detection” – $27.4 million.
The
House provided slightly higher funding than the Senate for two other programs:
“specialty
crops” (including sudden oak death) – $186.5 million in the House bill, $186
million in the Senate bill; and
“methods
development” – $21.686 million in the House bill, $20.686 million in the Senate
bill.
In the report accompanying its bill, the House called for two additional funding options to address emergencies. First, it set up a contingency fund of $470,000 to control outbreaks of insects, plant diseases, animal diseases and pest animals and birds to meet emergency conditions. Second, the report repeated language from past reports that authorizes the Secretary to take “such sums as may be deemed necessary” from other USDA programs in order to counter pest emergencies threatening any segment of U.S. agricultural production.
The Senate report addressed several high-profile tree pests. It called for complete eradication of the Asian longhorned beetle; mandated that APHIS report on its efforts to eradicate ALB and spotted lanternfly and to minimize spread of the polyphagous and Kuroshio shot hole borers; and to assist states that have recently detected the emerald ash borer. (This language is helpful, but it falls short of what I previously advocated – that APHIS continue efforts to prevent EAB spread, especially through movement of firewood.) The Senate report also urged APHIS to maintain FY19 level funding addressing the sudden oak death pathogen, in particular to improve understanding of the two strains of the pathogen present in Oregon’s forests link to blog to inform control and management techniques in wildlands. (Actually, management in wildlands falls largely to the Forest Service, with scientific input from both Agriculture Research Service and – to some extent – the NORS-DUC research nursery managed by APHIS.)
For a lengthier justification of my funding requests, see my earlier blog on APHIS funding
Funding for
Resistance Breeding through NIFA
As I pointed out in my blog in May, the 2018 Farm Bill included an amendment (Section 8708) that establishes a new priority for a grant program managed by the National Institute of Food and Agriculture. The amendment would support restoration to the forest of native tree species that have suffered severe levels of mortality caused by non-native insects, plant pathogens, or other pests. The amendment affects the Competitive Forestry, Natural Resources, and Environmental Grants Program under Section 1232(c)(2) of the Food, Agriculture, Conservation, and Trade Act of 1990 (16 U.S.C. 582A-8, as amended. However, this program has not been funded for more than a decade. In my blog, I asked you to support a $10 million appropriation to NIFA to fund a competitive grant program for such forests restoration.
Neither the House nor the Senate provided funding for
this program.
USFS
The House bill provides $277,155,000 for USFS Research and Development – nearly $20 million more than the Senate bill ($257,640,000). The House report links this increase to the recognition of the increasing risk to urban, rural, and wildland forests from insect and disease outbreaks and invasive plant infestations. The report calls on the Forest Service to develop a research program that addresses several priorities critical to forest health, including preventing the spread of disease and invasive species.
USFS engagement on pest issues with other federal agencies and state, local government, and private land managers is carried out through the Forest Health Management program under the State and Private Forestry division. The Senate bill and report are confusing because they have separated out salaries and other expenses. As a result, I can’t compare its figures to those in previous years or to those from the House. Partly for this reason, I urge you to support the House bill, which is quite clear in appropriating $103,736,000 for Forest Health Management, which is a programmatic increase of $19 million above the FY19 level and $29,919,000 above the budget request. I am encouraged by the House’ report, which encourages the Forest Service to address high priority invasive species, pests, and diseases, including the emerald ash borer and bark beetle infestations.
For longer explanations, see my earlier blog on USFS funding.
These bills show an increasing awareness of forest
pest issues in key funding committees in both the House and Senate. Let’s reinforce this message – and spread it
to the rest of Congress. Please contact your senators and representative and
ask them to support these funding levels.
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.
Faith Campbell receives award for activism from National Association of State Foresters; 2016
For nearly 30 years I have documented bioinvasion threats and gaps, first in three Fading Forests reports (available here), then in five years of blogging. Here I pull together that information and suggest — in most cases reiterate — steps to address these threats and gaps. I list sources of discussion of the underlying issues – other than my reports and blogs – in references at the end of this blog.
My
first premise is: robust federal leadership is crucial:
The Constitution gives primacy to
federal agencies in managing imports and interstate trade.
Only a consistent approach can
protect trees (and other plants) from non-native pests.
Federal agencies have more
resources than state agencies individually or in any likely collective effort
— despite decades of budget and staffing cuts.
My
second premise is: success depends on a continuing, long-term effort founded on
institutional and financial commitments commensurate with the scale of the threat.
This requires stable funding; guidance by research and expert staff; and engagement
by non-governmental players and stakeholders. Unfortunately, as I discuss
below, funding has not been adequate or stable.
My third premise is that programs’ effectiveness needs to be measured, not just effort (see the NECIS document referenced at the end of the blog).
SPECIFICS
Preventing
new introductions continues to be the most effective action. Mitigating options
decrease and damages increase once a non-native pest has entered the country –
much less become established (see Lovett et
al. 2016 and Roy et al. 2014). I
recognize that preventing new introductions poses an extremely difficult
challenge given the volume and speed of international trade and the strong
economic forces supporting free trade. These challenges have been exacerbated over
several decades by the political zeitgeist – the anti-regulatory ideology, the emphasis
on “collaborating” with “clients” rather than imposing requirements through
regulations. Although the current “America First” policy might reduce import
volumes and therefore reduce the invasive species threat to some extent, the
anti-regulatory stance has only strengthened.
containers at the Port of Long Beach, California
Decades of cutting key agencies’ budgets and personnel are another factor. However, the damage to America’s natural systems is so great that we must try harder to find more effective strategies (See the Fading Forest reports; my previous blogs; Lovett et al. 2016; and APHIS annual reports – e.g., the 2019 report here)
Prevention
Despite adoption and implementation of new international and national regulations to stem pest introductions, introductions continue – although probably at a lower level than would otherwise be the case. Delays in adoption of regulations (documented in Fading Forests II and III and my two recent 30-years-in-review blogs have facilitated damaging introductions and spread.
Solutions
Stakeholders press USDA
leadership to initiate rules intended to strengthen phytosanitary protection and
expedite their completion
APHIS promote and facilitate
analysis of current programs and policies by non-agency experts to ensure the
agency is applying most effective strategies (Lovett et al. 2016).
Adoption
of insufficiently protective regulations (documented in FFII, FFIII, two
30-years-in-review blogs) – adopted in part because APHIS is trying to
“balance” trade facilitation and phytosanitary protection – has further
contributed to damaging pests’ introduction and spread.
Solutions:
Boost
priority of preventing pest introductions by amending the Congressional finding
in the Plant Protection Act [7 USC 7701(3)] as follows
Existing language: “[I]t is the
responsibility of the Secretary [of Agriculture] to facilitate exports, imports
and interstate commerce in . . . commodities that pose a risk of harboring
plant pests or noxious weeds in ways that
will reduce, to the extent practicable, as determined by the Secretary, the
risk of dissemination of plant pests and noxious weeds .… “
Amend to read as follows: “…. in ways that will reduce prevent, to the greatest extent practicable feasible, as determined by the Secretary, …” [emphasis added]
Adopt several actions to
strengthen phytosanitary protections at the point of origin (Lovett et al. 2016)
Expand
pre-clearance partnerships — as authorized for plants under Q-37 regulations
and ISPM-36
Expand
sentinel tree programs
Promote
voluntary substitution of packaging made from materials other than solid wood.
APHIS
doesn’t use the enforcement powers that it has under Plant Protection Act (see
several of my past blogs)
Solutions:
CBP inspectors search for pests in a pallet; CBP photo
APHIS follow the lead of Customs and Border Protection and begin penalizing importers on the first instance of their wood packaging not being in compliance with ISPM#15 (see blog here).
APHIS prohibit use of wood packaging by countries and importers of categories of imports that – over the 13 years since implementation – have developed a record of frequent violations of ISPM#15.
APHIS use its authority per revised Q-37 regulations to negotiate with countries that export plants to the U.S. to establish “integrated measures” programs aimed at minimizing the risk of associated pests being transported to the U.S.
APHIS use its authority per revised Q-37 to place in the “Not Authorized for Import Pending Pest Risk Assessment (NAPPRA) “limbo” category genera containing North American “woody” plants (see Roy et al. 2014; Lovett et al. 2016).
Spread within the
U.S.
The
United States lacks a coordinated system to prevent pest spread within the
country (see Fading Forests III Chapter 5). Even our strictest methods, like APHIS’s
quarantines regulating interstate movement of goods, have failed to curtail
spread of significant pests. The most obvious example is the emerald ash borer.
The regulations governing movement of the sudden oak death pathogen in the nursery trade have also failed: there have been periodic outbreaks in which the pathogen has been spread to nurseries across the country. Between 2003 and 2011, a total of 464 nurseries located in 27 states tested positive for the pathogen, the majority as a result of shipments traced from infested wholesalers. In 2019, plants exposed to the pathogen were again shipped to 18 states; eight of those states have confirmed that their plant retailers received infected plants (see my blog from summer here).
Another
serious gap is the frequent failure of APHIS and states to adopt official
programs targetting bioinvaders that will be difficult to control because of
biological characteristics or cryptic natures – even when severe impacts are
demonstrated. Recent examples include the laurel wilt disease complex, goldspotted
oak borer, polyphagous and Kuroshio shot hole borers and associated pathogens,
and even the spotted lanternfly (although the last has received significant
funds from APHIS.)
redbay killed by laurel wilt disease, Georgia; photo by Scott Cameron
Solutions:
APHIS apply much more stringent
regulations to interstate movement, based on a heightened priority for
prevention in contrast to facilitating interstate trade. E.g., prohibit nurseries on the West Coast from shipping P. ramorum hosts to states where the pathogen
is not established.
APHIS encourage states to adopt
quarantines and regulations aimed at preventing spread of invasive pests to
regions of the state that are not yet infested. For example, the sudden oak
death pathogen in California and Oregon; the borers in southern California.
APHIS abandon plans to deregulate
emerald ash borer and step up its support for state regulations on firewood.
APHIS stop dumping pests it no
longer wants to regulate onto the states through the “Federally Recognized
State Manage Phytosanitary (FRSMP) program”.
APHIS revise its policies so that
the “special needs exemption” [7 U.S.C. 7756] actually allows states to adopt
more stringent regulations to prevent introduction of APHIS-designated
quarantine pests (see Fading Forests III Chapter 3).
To help fill the gaps, the states are trying to coordinate their regulations in some important areas. The most advanced example is the voluntary Systems Approach to Nursery Certification, or SANC program. APHIS has supported this initiative, including by funding from the Plant Pest and Disease Management and Disaster Program (see below). However, it is a slow process; USDA funds first became available in 2010. The states are trying to coordinate on firewood, but we don’t yet know what the process will be.
Funding shortfalls (See the three Fading Forests
reports, my blogs about appropriations)
Increase APHIS’ access to emergency
funds from the Commodity Credit Corporation by
amending the Plant Protection Act [7 U.S.C. 7772 (a)] to include this
new definition of “emergency”:
the term “emergency” means any
outbreak of a plant pest or noxious weed which directly or indirectly threatens
any segment of the agricultural production of the United States and for which
the then available appropriated funds are determined by the Secretary to be
insufficient to timely achieve the arrest, control, eradication, or prevention
of the spread of such plant pest or noxious weed.
Although APHIS has the most
robust prevention program of any federal agency, its funding is still
inadequate. Stakeholders should lobby the Congress in support of higher annual
appropriations.
The Plant
Pest and Disease Management and Disaster Program (now under Section 7721 of the
Plant Protection Act) has provided at least $77 million for tree-pest
programs (excluding NORS-DUC & sentinel plant programs and other programs)
since FY 2008. Much useful work has been carried out with these funds. However,
these short-term grants cannot substitute for stable, long-term funding. I
reiterate my call for stakeholders to lobby the Congress to provide larger
appropriations to the APHIS Plant Protection program and Forest Service Forest
Health Protection and Research programs.
Long-term Responses
to Bioinvasive Challenge
More stakeholders are advocating raising the priority of – and providing adequate resources to – such long-term solutions as biocontrol and breeding trees resistant to pests and restoring them to our forests. Advocates include the state forestry agencies of the Northeast and Midwest, some non-governmental organizations, some academics, and individual USFS scientists. One effort resulted in inclusion of language in the 2018 Farm Bill (see blog here) – although this approach has apparently run into a dead end. The new emphasis on breeding has so far not been supported by agency or Congressional leaderships.
test planting of an American chestnut bred to be resistant to chestnut blight
Solutions:
USFS convene workshop of the
federal, state, National Academy, academic, and NGO groups promoting resistance
breeding in order to develop consensus on priorities and general structure of program.
Explicitly include evaluation of the
CAPTURE Project’s (see blog here) efforts to
set priorities to guide funding allocations and policies; and proposals for
providing needed supportive infrastructure – facilities, trained staff in
various disciplines. (See my blogs here.)
Report results of meeting to USDA
leadership, Congress, and stakeholders
Then ensure implementation of the
accepted approach by both Research and Development and Forest Health Protection
programs. Include provisions to provide sustainable funding.
These proposed actions still do not address ways to correct the provisions of the international phytosanitary agreements (World Trade Organization and International Plant Protection Convention) that complicate – or preclude – efforts to prevent introduction of pests currently unknown to science. This issue is discussed in Fading Forests II. A current example is beech leaf disease (described here).
Continuing
inadequate engagement by stakeholders
Most
constituencies that Americans expect to protect our forests don’t press
decision-makers to fix the problems I have identified above: inadequate
resources, weak and tardy phytosanitary measures. Some of these stakeholders
are other federal agencies, or state agencies – or their staffs. They face
restrictions on how “political” they can be. But where are the professional and scientific associations,
representatives of the wood products industry, forest landowners, environmental NGOs and their funders, urban
tree advocates Efforts by me, USDA, and others to better engage these groups
have had disappointing results.
As
I have documented, groups of USFS scientists have made several attempts to
document the extent of invasive species threats and impacts and to set
priorities. So far, they have not gained much traction. Another USFS attempt,
Poland et al. in press, will appear
at the end of the year. Will this be more successful?
I
detect growing attention to educating citizen scientists for early detection;
but if there is an inadequate – or no – official response to their efforts
won’t people become discouraged?
SOURCES
Lovett,
G.M., M. Weiss, A.M. Liebhold, T.P. Holmes,
B. Leung, K.F. Lambert, D.A. Orwig, F.T. Campbell, J. Rosenthal, D.G. McCullough,
R. Wildova, M.P. Ayres, C.D. Canham, D.R. Foster, SL. Ladeau, and T. Weldy.
2016. NIS forest insects and pathogens in the US: Impacts and policy options. Ecological
Applications, 26(5), 2016, pp. 1437–1455
National Environmental Coalition on Invasive Species “Tackling the Challenge.”
Poland,
T.M., Patel-Weynand, T., Finch, D., Miniat, C. F., and Lopez, V. (Eds) (2019),
Invasive Species in Forests and Grasslands of the United States: A
Comprehensive Science Synthesis for the United States Forest Sector. Springer Verlag. (in press).
Roy,
B.A., H.M Alexander, J. Davidson, F.T Campbell, J.J Burdon, R. Sniezko, and C.
Brasier. 2014. Increasing forest loss worldwide from P&Ps requires new
trade regulations. Front Ecol Environ 2014; 12(8): 457–465
dead whitebark pine in Crater Lake National Park photo by F.T. Campbell
I began studying and writing about the threat to North America’s forests from non-native insects and pathogens in the early 1990s – nearly 30 years ago. I reported my analyses of the evolving threat in the three “Fading Forests” reports – coauthored by Scott Schlarbaum – in 1994, 2003, and 2014. These reports are available here.
So what has changed over those 30 years? What remains the same? Why have both the changes and the stasis occurred? What can we do to fix the gaps, close unaddressed pathways, strengthen flabby policies? I will address these issues in this and following blogs.
experimental American chestnut planted in Fairfax County, VA photo by F.T. Campbell
What has changed
since the early 1990s:
Adoption and implementation of significant new international and national regulations and programs aimed at preventing introductions of non-native invasive species.
Despite the welter of new regulations, an alarming increase in numbers of highly damaging forest pests established in the country. (By my count, about 50 new species have established on the continent, six on Pacific islands; see details below.)
Alarming spread of established pests to new geographic regions and new hosts (e.g., emerald ash borer in 35 states and 5 provinces; laurel wilt disease across the range of redbay and swamp bay; rapid ‘ōhi‘a death on three of the main Hawaiian islands).
Introductions via unexpected pathways and vectors far removed from phytosanitary agencies’ usual targets, e.g., ship superstructures, imported steel and stone …
What has remained the
same since the early 1990s:
Inadequate
resources provided to response and recovery efforts.
Available
funding focused on only a few of the more than 90 species causing damage.
Adoption
of insufficiently protective regulations that have failed to prevent
introduction and spread of tree-killing pests.
Lengthy
delays in implementing programs that tighten controls – another factor in
continuing introductions and spread.
Continued
importance of expected pathways – nursery stock and raw wood, especially
crates, pallets, and other forms of wood packaging.
Federal
and state agencies still choose not to take action on pests e.g., goldspotted oak borer, polyphagous
and Kuroshio shothole borers, beech leaf disease.
Inadequate
coordination despite several efforts to set priorities.
Spurts
of attention by media and political decision-makers, contrasted by lengthy
periods of inattention.
Failure
of most stakeholders to support efforts to prevent and respond to introductions
of tree-killing pests.
Details: The Situations
Then and Now
(Many of the individual species mentioned here are described more fully here. Full citations of sources are at the end of blog.)
American elm on the National Mall, Washington, D.C.
photo by USDA Agricultural Research Service
In 1993:
The number of non-native forest pest species established in the U.S. was estimated at between 300 (Millers et al. 1993) and 380 (Mattson et al., 1994; Liebhold et al., 1995) .
The area suffering the greatest numbers and impacts was the Northeast.
Several highly damaging pests that had been established for decades, including chestnut blight, white pine blister rust, Port-Orford-cedar root disease, Dutch elm disease, hemlock woolly adelgid, butternut canker, and dogwood anthracnose were receiving some attention but continued to spread.
USDA Forest Service funding for management of exotic pest infestations was crisis-oriented, with “… priorities … set under political pressures for immediate answers, with too much regard for short-term problems and too little consideration for broader management objectives.” (NAS 1975)
Since few high-profile pests had been introduced in recent years, APHIS was not actively engaged. In FY92, APHIS spent $20 million on efforts to eradicate the Asian gypsy moth. The narrow focus is illustrated by the fact that in FY93, more than two-thirds of all USDA tree pest control funds were devoted to efforts to suppress or eradicate the European gypsy moth (See FFI).
Concern about possible new introductions had grown; it focused on proposals to import unprocessed wood from Siberia, New Zealand, and Chile. The USDA Forest Service, academic scientists, and therefore APHIS emphasized the risks of known Asian pests, e.g., Asian gypsy moth, to western coniferous forests (See FFI). While individual scientists had expressed concern about wood packaging material, there was little public discussion of this threat.
We would learn later that several of the most damaging pests were already present in the country but not yet recognized – Asian longhorned beetle, sudden oak death pathogen, probably emerald ash borer.
beech leaf disease
photo by John Pogacnik
In 2019:
Numbers of non-native insects and pathogens attacking trees in North America approach 500 species. (In Fading Forests III, I calculated that by the first decade of the 21st Century, the number had risen to at least 475. Several more have been detected since 2014. More than 181 exotic insects that feed on woody plants had established in Canada. (Source: USDA APHIS. 2000. Wood packaging risk assessment.)
Of these, 91 are considered “serious” threats (Guo et al. 2019). This estimate excludes pests native to portions of North America that are causing severe damage in naïve hosts – e.g., goldspotted oak borer; pests of palms; and pests attacking trees on U.S. Pacific and Caribbean islands.
Introductions had continued.
Between 1980 and 2016, at least 30 non-native species of wood- or bark-boring insects (Scolytinae / Scolytidae) were newly detected in the U.S. (Haack and Rabaglia 2013; Rabaglia et al. 2019). A few of these are highly damaging, e.g. redbay ambrosia beetle, polyphagous and Kuroshio shothole borers.
In addition to these 30 new pests, other highly damaging tree-killing pests probably introduced since the 1980s include (on the continent):
Eight Cerambycids such as Asian longhorned beetle (Wu et al. 2017)
7 Agrilus, including emerald ash borer and soapberry borer; plus goldspotted oak borer transported from Arizona to California (Digirolomo et al. 2019; R. Haack, pers. comm.)
Sirex woodwasp
Pests of palm trees, e.g., red palm mite, red palm weevil, South American palm weevil
Spotted lanternfly
Beech leaf disease
Also not included in the above estimate and lists are tree-killing pests on America’s Pacific Islands :
‘ōhi‘a rust
Cycad scale
Cycad blue betterfly
Erythrina gall wasp
two Ceratocystis pathogens that cause rapid ‘ōhi‘a death
Coconut rhinoceros beetle
Authorities also carried out approximately 25 eradication programs targetting introductions of the Asian gypsy moth (USDA Pest Alert Asian Gypsy Moth plus additional outbreaks since 2014).
Impacts of exacerbated tree mortality rates linked to these introduced pests are seen across wide swaths of the country, and affect widespread species, genera, and families.
dead redbay in Claxton, Georgia photo by Scott Cameron
I will discuss the risk of continuing new introductions in a separate blog.
Trying to Develop
the Big Picture and Set Priorities
In
recent years, USDA Forest Service scientists have made several attempts to
provide nation-wide assessments of the impact of these pests and criteria for
establishing priorities.
The
National Insect and Disease Forest Risk Assessment predicted the loss of basal
area to various pests over the 15-year time period 2012 – 2027. The assessment
predicted the following losses for specific species: 90% for redbay; 60% for whitebark
pine; more than 40% for limber pine; 24% for tanoak; 11% for coast live oak; 6%
for eastern and Carolina hemlock; 27% for eight species of ash; 20% for
American elm; 19% for red oak; 18% for American beech (Krist et al. 2014).
A separate group of scientists found that, nation-wide, non-native forest pests are causing an approximate 5% increase in total mortality by tree volume (Randy Morin at NEFPC). For details on Dr. Morin’s findings, see my blog here.
A third approach to developing a nation-wide picture, Project CAPTURE, (and my blog here) utilized FIA data to develop priorities for conservation action. Fifteen species were placed in the highest priority category, including Florida torreya (Torreya taxifolia), American chestnut and Allegheny and Ozark chinquapins, redbay, five species of ash, two species of hemlock, Port-Orford cedar, tanoak, and butternut (Potter et al. 2019(b).
According
to Project CAPTURE, the non-native pests affecting the largest number of hosts
are the European gypsy moth, which attacks 65 hosts; and oak wilt (Bretziella fagacearum), which infects 61
hosts. The Asian longhorned beetle attacks 43 hosts (Potter et al. 2019(b).
I note that several other non-native pests also have high numbers of host species. In the Project CAPTURE study, these pests are ranked lower because the project limited its evaluation to the five agents with the greatest effect on any particular host. Thus, of the 18 native tree species that host one or both of the invasive shothole borers and associated Fusarium disease complex (PSHB website), the project included only six. Of the 22 tree species listed by APHIS as hosts of Phytophtora ramorum, the project included 12 (K. Potter, pers. comm. April 17, 2019).
SOD-killed tanoak on the Big Sur peninsula, California photo by Matteo Garbelotto, University of California Berkeley
More extensive discussions of
non-native pests’ impacts are provided in Lovett et al. 2006, Lovett et al.
2016, and Potter et al. 2019. A
book-length discussion of invasive species impacts – ranging from feral hogs to
invasive plants, is expected in December; look for Poland et al. (in press).
SOURCES
Aukema,
J.E., D.G. McCullough, B. Von Holle, A.M. Liebhold, K. Britton, & S.J.
Frankel. 2010. Historical Accumulation of Nonindigenous Forest Pests in the
Continental United States. Bioscience. December
2010 / Vol. 60 No. 11
Digirolomo, M.F., E. Jendek, V.V. Grebennikov, O. Nakladal. 2019. First North American
record of an unnamed West Palaearctic Agrilus (Coleoptera:
Buprestidae) infesting European beech (Fagus sylvatica) in New York
City, USA. European Journal of
Entomology. Eur. J.
Entomol. 116: 244-252, 2019
Guo,
Q., S. Fei, K.M. Potter, A.M. Liebhold, and J. Wenf. 2019. Tree diversity
regulates forest pest invasion. Proceedings of the National Academy of Sciences
of the United States of America. www.pnas.org/cgi/doi/10.1073/pnas.1821039116
Haack,
R.A. and R.J. Rabaglia. 2013. Exotic Bark and Ambrosia Beetles in the USA:
Potential and Current Invaders. CAB International 2013. Potential Invasive
Pests of Agricultural Crops (ed. J. Peña)
Krist,
F.J. Jr., J.R. Ellenwood, M.E. Woods, A. J. McMahan, J.P. Cowardin, D.E. Ryerson,
F.J. Sapio, M.O. Zweifler, S.A. Romero 2014. National Insect and Disease Forest
Risk Assessment. United States Department of Agriculture Forest Service Forest
Health Technology Enterprise Team FHTET-14-01
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
Liebhold, A. M., W. L. MacDonald, D. Bergdahl, and V. C. Mastro. 1995. Invasion by exotic forest pests: a threat to forest ecosystems. Forest Sci., Monograph 30. 49 pp.
Lovett,
G.M., C.D. Canham, M.A. Arthur, K.C. Weathers, and R.D. Fitzhugh. Forest
Ecosystem Responses to Exotic Pests and Pathogens in Eastern North America. BioScience
Vol. 56 No. 5 (May 2006)
Lovett,
G.M., M. Weiss, A.M. Liebhold, T.P. Holmes,
B. Leung, K.F. Lambert, D.A. Orwig, F.T. Campbell, J. Rosenthal, D.G.
McCullough, R. Wildova, M.P. Ayres, C.D. Canham, D.R. Foster, SL. Ladeau, and
T. Weldy. 2016. NIS forest insects and pathogens in the US: Impacts and policy
options. Ecological Applications, 26(5), 2016, pp. 1437–1455
Mattson,
W. J., P. Niemela, I. Millers, and Y. Ingauazo.
1994. Immigrant phytophagous insects on woody plants in the United
States and Canada: an annotated list.
USDA For. Ser. Gen. Tech. Rep. NC-169, 27 pp.
Millers, I. United States
Department of Agriculture, Forest Service Entomologist, Forest Health
Protection Northeastern Area State and Private Forestry. Durham, NH. Personal
communication to F.T. Campbell, 1993.
Morin, R. presentation at Northeastern Forest Pest Council 81st Annual
Meeting, March 12 – 14, 2019, West
Chester, Pennsylvania
National Academy of Sciences. 1975. Forest Pest Control. Washington, D.C.
Poland,
T.M., Patel-Weynand, T., Finch, D., Miniat, C. F., and Lopez, V. (Eds) (2019),
Invasive Species in Forests and Grasslands of the United States: A
Comprehensive Science Synthesis for the United States Forest Sector. Springer Verlag. (in press).
Potter,
K.M., M.E. Escanferla, R.M. Jetton, and G. Man. 2019. Important Insect and
Disease Threats to US Tree Species and Geographic Patterns of Their Potential
Impacts. Forests 2019, 10, 304.
Potter,
K.M., Escanferla, M.E., Jetton, R.M., Man, G., Crane, B.S. 2019. Prioritizing
the conservation needs of US tree spp: Evaluating vulnerability to forest insect
and disease threats, Global Ecology and Conservation (2019), doi:
https://doi.org/10.1016/
Rabaglia,
R.J., A.I. Cognato, E. R. Hoebeke, C.W. Johnson, J.R. LaBonte, M.E. Carter, and
J.J. Vlach. 2019. Early Detection and Rapid Response. A Ten-Year Summary of the
USDA Forest Service Program of Surveillance for Non-Native Bark and Ambrosia
Beetles. American Entomologist Volume 65, Number 1
U.S.
Department of Agriculture, Animal and Plant Health Inspection Service. 2009.
Risk analysis for the movement of wood packaging material (WPM) from
Canada into the US.
Wu,Y.,
N.F. Trepanowski, J.J. Molongoski, P.F. Reagel, S.W. Lingafelter, H. Nadel1,
S.W. Myers & A.M. Ray. 2017. Identification of wood-boring beetles
(Cerambycidae and Buprestidae) intercepted in trade-associated solid wood
packaging material using DNA barcoding and morphology Scientific Reports 7:40316
Photo of infested cactus at Cabo Rojo National Wildlife Refuge, Puerto Rico. Taken August 20, 2018 by Yorelyz Rodríguez-Reyes
Three and a half years ago, I blogged about the threat to columnar cacti in Puerto Rico from the Harrisia cactus mealybug. The mealybug clearly threatens the endemic cacti of the Caribbean islands, and possibly some of the hundreds of other columnar cacti growing across two million square miles of desert ecosystems that straddle the U.S.-Mexico border region.
I am pleased to report that scientists continue efforts to find biocontrol agents to reduce this insect’s damage on Caribbean islands. Much of this work is being done by the Center for Excellence in Quarantine and Invasive Species at University of Puerto Rico. The team consists of Michael West Ortiz, Yorelys Rodrígues Reyes, Ferdinand Correa and Jose Carlos Verle Rodrigues.
As of February 2019, the Center is conducting host specificity tests on a primary parasitoid of the Harrisia Cactus mealybug — Anagyrus cachamai. This wasp was found as a result of almost a decade of searching in South America and other locations. It is native to Argentina and Paraguay (Triapitsyn et al. 2018; sources listed at the end of the blog).The Center also continues surveys and studies of other primary and secondary parasitoids of the mealybug.
The work to develop a biocontrol agent for the
mealybug continues despite continuing uncertainty about the true species of the mealybug. At the time
of its discovery on Puerto Rico, the mealybug was believed to belong to a
species used as a biocontrol agent for invasive cacti in Australia and South
Africa, designated as Hypogeococcus
pungens.
However, H. pungens is now thought to
be a species complex, and the species in Puerto Rico differs from the earlier
designation (Triapitsyn et al.
2018).
Apparently
the mealybug was introduced in Puerto Rico around 2000 — probably on the ornamental common
purslane (Portulaca olerácea), an
annual succulent. (Note: the
introduction was on a host different from the vulnerable cacti.) Within five
years of the first detection in San Juan, the mealybug was sighted on cacti on
the other side of the island in the Guánica State Forest and Biosphere Reserve.
By 2010, the mealybug was widely distributed in most dry districts. Surveys
found it in all 11 municipalities surveyed in southern Puerto Rico. At some
locations, infestation levels were extremely high – e.g., 86% of stems surveyed were infested at Guánica. Infestation
rates were lower in other municipalities. As of 2010, infestations were
estimated to be present on about 1,400 km2 on the southern coast;
the rate of new infestations suggests that the mealybug was spreading rapidly
(Segarra-Carmona et al. 2010). I have been unable to obtain more recent
estimates.
The
mealybug impacts seven of 14 native cactus species occurring in dry forests of
the island, including three endemic and two endangered species in the subfamily
Cactoideae. The two endangered species are Harrisia
portoricensis and Leptocereus grantianus (USDA ARS). The tissue
damage caused by the mealybug interferes with sexual reproduction and can cause
direct mortality of the plant (Triapitsyn et
al. 2018). These
cacti provide food or shelter for endemic bats, birds, moths and other
pollinators (Segarra & Ramirez; USDA ARS). The mealybug is also now killing
native cacti on the U.S. Virgin Islands (H. Diaz-Soltero pers. comm. August
2015).
USDA Funds Conservation Efforts Despite
Apparent Absence of a Constituency Calling for Such Action
Efforts
to identify and test possible biocontrol agents targetting the Harrisia cactus
mealybug received significant funds from the Plant
Pest and Disease Management and Disaster Prevention Program. This is a
competitive grant program managed by APHIS. It is permanently funded and thus
not subject to the vagaries of annual appropriations. Until last year, this
program operated under Section
10007 of the 2014 Farm Bill. With passage of a new Farm Bill, it is now
designated as Section 7721 of the Plant Protection Act.
Since Fiscal Year 2018, APHIS has had authority to spend more than $60 million per year on this program. In Fiscal Year 2017, , the program provided $120,000 to an unspecified federal agency, $70,000 to an academic institution in Puerto Rico (presumably the Center), $15,000 to another academic institution in California, and $3,000 divided among two APHIS facilities – for a total of $208,000. The next round of funds came in FY19, when the program provided $277,267 to an unspecified federal agency to continue work on biocontrol. In addition, the program provided $78,507 to an unspecified federal agency to “safeguard[e] genetic diversity of native and listed cacti threatened by Harrisia cactus mealybug in Puerto Rico”.
No Apparent Action on
Threats to Opuntia Cacti
In my earlier blog, I also described the threat to flat-padded Opuntia (prickly pear) cacti from the cactus moth Cactoblastis cactorum. Various federal, state, and academic entities received $463,000 from the permanent fund in Fiscal Year 2016 and another $100,000 in FY2017. No cactus moth programs have received funds in more recent years.
SOURCES
Segarra-Carmona, A.E., A.
Ramirez-Lluch. No date. Hypogeococcus pungens (Hemiptera: Pseudococcidae): A
new threat to biodiversity in fragile dry tropical forests.
Segarra-Carmona,
A.E., A. Ramírez-Lluch, I. Cabrera-Asencio and A.N. Jiménez-López. 2010. FIRST REPORT OF A NEW INVASIVE MEALYBUG, THE
HARRISIA CACTUS MEALYBUG HYPOGEOCOCCUS PUNGENS (HEMIPTERA: PSEUDOCOCCIDAE). J.
Agrie. Univ. RR. 94(1-2):183-187 (2010)
Triapitsyn,
Aguirre, Logarzo, Hight, Ciomperlik, Rugman-Jones, Rodriguez. 2018. Complex of
primary and secondary parasitoids (Hymenoptera: Encyrtidae and Signiphoridae)
of Hypogeococcus spp. mealybugs (Hemiptera: Pseudococcidae) in the New World. Florida
Entomologist Volume 101, No. 3 411
USDA Agriculture Research Service, Research Project:
Biological Control of the Harrisia Cactus Mealybug, Hypogeococcus pungens
(Hemiptera:pseudococcidae) in Puerto Rico Project Number: 0211-22000-006-10
Project Type: Reimbursable
West Ortiz, M. pers. comm. February 2019
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by Faith Campbell
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