feral hogs in Missouri; photo by Missouri Department of Conservation
A new report by several experts confirms fears that the feral pig threat is widespread and re-emphasizes the value of taking action early. (I have blogged several times about efforts to manage damaged caused by feral hogs – see here and here.
Lewis
et al. (full reference at end of
blog) used two national-scale data sets to estimate historical, current, and
future potential population size of wild pigs in the U.S. from 1982 to 2016.
They
found that both wild pig distribution and abundance have nearly tripled over
this period (from ~2.4 to 6.9 million). If no effective action is taken and pigs
spread to all available habitat, the U.S.
wild pig population could reach ~21.4 million at some unspecified future date. This
would represent a 210% increase above the 2016 population; or a 784% increase
above the 1982 population.
The authors cite successful control of wild pigs in Colorado, New Mexico, Michigan, and Nebraska as evidence of the value of early detection and rapid response.
Lewis
et al. provide brief summaries of
economic and ecological damage caused by feral hogs. They damage a wide range
of ecological communities, especially riparian areas, grasslands, and deciduous
forests. Biological diversity is hurt through habitat destruction, direct
predation, and competition for resources. In addition, wild pigs can host a
suite of viruses, bacteria, and parasites, many of which can be transmitted to
other wildlife, humans, and livestock.
The
report notes that much of the recent spread of pigs has been caused by widespread
and illegal releases of wild animals for sport hunting. Other contributing factors
are land-use patterns, because hogs do well in agricultural areas. Warmer
winter temperatures and increased forest mast production are also to blame –
both related to climate-change
Wild
pigs can persist in a range of environments, including cold northern climates,
arid regions, and mixed forests. That is, all regions of the continental U.S. The
vast majority of states – especially in the West, North, and East – could see
major expansions in wild pig populations if animals are allowed to become
established over currently unoccupied habitat.
While
states that have had large established wild pig populations – e.g., Texas, California, and Florida – will
not see major expansions, damage is already severe and widespread. Texas alone
has an estimated 2.5 million feral hogs!
Preventing
the alarming expansion of feral hog populations outlined above, Lewis et al. call for adoption and
implementation of proactive management. The
priority is to quickly identify and eradicate populations that invade
unoccupied habitat. This applies particularly to those states which currently
have low populations of feral hogs.
The
same approach can be applied within states. Officials can use one data set to
identify areas where wild pigs are currently absent and the predicted
population density data to designate priority areas to counter spread. Such
efforts should include public education and outreach, regulatory enforcement,
and surveillance.
Lewis
et al. note that implementation of the
proposed strategy will require a coordinated
effort among federal, state, and local governments and the public. They
call especially for state regulations
classifying feral hogs as an invasive and harmful species supported by action
to halt pig translocation for the purposes of recreational sport hunting.
The authors promised that the findings of the study would be applied by the National Feral Swine Damage Management Program, which is led by USDA APHIS. One of the “tactics” to achieve Objective 2.4 in the APHIS Strategic Plan for 2019-2023 says the agency will “expand feral swine damage management for agricultural, livestock, property, ecological and human health and safety purposes.” Still, states will find it challenging to take any actions opposed by hunters.
At the end of June 2019, the U.S. Department of Agriculture (USDA) announced a $75 million program called the Feral Swine Eradication and Control Pilot Program (FSCP). (This works out to about $15 million per year.) The program is a joint effort by the Natural Resources Conservation Service (NRCS) and APHIS. It was established by the 2018 Farm Bill. Additional information is available at the program webpage.
The
webpage describes how to apply for funding for projects lasting up to three
years. The pilot projects will
consist broadly of three coordinated components: 1) feral swine removal by
APHIS; 2) restoration efforts supported by NRCS; and 3) assistance to producers
for feral swine control provided through partnership agreements with
non-federal partners.
The initial funding will target specific locations in the South that have experienced recent increases in wild pigs (shown on the map below). The goal is to reduce the numbers of pigs (and associated damage) in those identified localized areas of the South. These “pilot” areas have been identified by the USDA Secretary as under threat from feral swine. The first round of projects – 20 projects – are targetted at a few counties in Alabama, Arkansas, Florida, Georgia, Louisiana, Oklahoma, North Carolina, South Carolina, and Texas. APHIS has determined these states and California have highest feral swine populations.
The new program builds on successes in recent years. Funding of APHIS’ feral hog program at about $20 million per year has helped several states become “pig free”. Idaho, Iowa, Maine, New Jersey and New York are currently monitoring (using eDNA and scat dogs) to make sure that the pigs are truly gone.
SOURCE
Lewis, J.S., J.L. Corn, J.J. Mayer, T.R. Jordan, M.L. Farnsworth, C.L. Burdett, K.C. VerCauteren, S.J. Sweeney, R.S. Miller. 2019. Historical, current, and potential population size estimates of invasive wild pigs (Sus scrofa) in the United States. Biological Invasions, Vol. 21, No. 7, pp. 2373-2384.
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.
frogs in California killed by chytrid fungus photo by Rick Kyper, US Fish and Wildlife Service
I expect you have heard about the report issued on May 6 by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. The executive summary is available here
Based on thousands of scientific
studies, the report concludes that the biosphere, upon which humanity as a whole
depends, is being altered to an unparalleled degree across all spatial scales. The
trends of decline are accelerating. As many as 1 million species (75% of which are
insects) are threatened with extinction, many within decades.
Humans dominate Earth: natural
ecosystems have declined by 47% on average. Especially hard-hit are inland
waters and freshwater ecosystems: only 13% of the wetland present in 1700
remained by 2000. Losses have continued rapidly since then.
The report lists the most important
direct drivers of biodiversity decline – in descending order – as habitat loss
due to changes in land and sea use; direct exploitation of organisms; climate
change; pollution; and invasive species. The relative importance of each driver
varies across regions.
If you have been paying attention, these
conclusions are not “news”.
However, the report serves two valuable
purposes. First, it provides a global overview, a compilation of all the data
and trends. Second, the report ties the direct drivers to underlying causes
which are in turn underpinned by societal values and behaviors. Specifically
mentioned are production and consumption patterns, human population dynamics
and trends, trade, technological innovations, and governance (decision making
at all levels, from local to global).
The report goes to great lengths to
demonstrate that biological diversity and associated ecosystem services are
vital for human existence and good quality of life – especially for supporting
humanity’s ability to choose alternative approaches in the face of an uncertain
future. The report concludes that while more food, energy and materials than
ever before are now being supplied to people, future supplies are undermined by
the impact of this production and consumption on Nature’s ability to provide.
The report also emphasizes that both the
benefits and burdens associated with the use of biodiversity and ecosystem
services are distributed and experienced inequitably among social groups,
countries and regions. Furthermore, benefits provided to some people often come
at the expense of other people, particularly the most vulnerable. However, there are also synergies – e.g., sustainable agricultural practices
enhance soil quality, thereby improving productivity and other ecosystem
functions and services such as carbon sequestration and water quality
regulation.
The report contains vast amounts of data
on the recent explosion of human numbers and – especially – consumption – of
agricultural production, fish harvests, forest products, bioenergy production …
and on the associated declines in “regulating” and “non-material contributions”
ecosystem services. In consequence, the report concludes, these recent gains in
material contributions are often not sustainable.
While invasive species rank fifth as a
causal agent of biodiversity decline globally, alien species have increased by
40% since 1980, associated with increased trade and human population dynamics
and trends. The authors report that nearly 20% of Earth’s surface is at risk of
bioinvasion. The rate of invasive species introduction seems higher than ever
and shows no signs of slowing.
The report notes that the extinction
threat is especially severe in areas of high endemism. Invasive species play a
more important role as an extinction agent in many such areas, especially
islands. However, some bioinvaders also have devastating effects on mainlands;
the report cites the threat of the pathogen Batrachochytrium
dendrobatidis to nearly 400 amphibian species worldwide.
The report also mentions that the combination
of species extinctions and transport of species to new ecosystems is resulting
in biological communities – both managed and unmanaged — becoming more similar
to each other — biotic homogenization.
The report notes that human-induced
changes are creating conditions for fast biological evolution of species in all
taxonomic groups. The authors recommend adopting conservation strategies
designed to influence evolutionary trajectories so as to protect vulnerable species
and reduce the impact of unwanted species (e.g.,
weeds, pests or pathogens).
The report says conservation efforts
have yielded positive outcomes – but they have not been sufficient to stem the
direct and indirect drivers of environmental deterioration. Since 1970, nations
have adopted six treaties aimed at protection of nature and the environmental,
but few of the strategic objectives and goals adopted by the treaties’ parties
are being realized. One objective that is on track to partial achievement is
the Aichi Biological Diversity Target that calls for identification and
prioritization of invasive species.
That might well be true – but I would not consider global efforts to manage invasive species to be a success story in any way. I have blogged often about studies showing that introductions continue unabated … and management of established bioinvaders only rarely results in measurable improvements. [For example, see here and here.]
The report gives considerable attention
to problems caused by some people’s simultaneous lack of access to material
goods and bearing heavier burden from pollution and other negative results of
biodiversity collapse. Extraction of living biomass (e.g. crops, fisheries) to meet the global demand is highest in
developing countries whereas material consumption per capita is highest in developed countries. The report says that
conservation of biodiversity must be closely linked to sustainable approaches
to more equal economic development. The authors say both conservation and economic
goals can be achieved – but this will require transformative changes across
economic, social, political and technological factors.
One key transformation is changing
people’s conception of a good life to downplay consumption and waste. Other
attitudinal changes include emphasizing social norms promoting sustainability
and personal responsibility for the environmental impacts of one’s consumption.
Economic measures and goals need to address inequalities and integrate impacts
currently considered to be “economic externalities”. The report also calls for inclusive
forms of decision-making and promoting education about the importance of
biodiversity and ecosystem services.
Economic instruments that promote
damaging, unsustainable exploitation of biological resources (or their damage
by pollution) include subsidies, financial transfers, subsidized credit, tax
abatements, and commodity and industrial goods prices that hide environmental
and social costs. These need to be changed.
Finally, limiting global warming to well
below 2oC would have multiple co-benefits for protecting
biodiversity and ecosystem services. Care must be exercised to ensure that large-scale
land-based climate mitigation measures, e.g.,
allocating conservation lands to bioenergy crops, planting of monocultures,
hydroelectric dams) do not themselves cause serious damage to biodiversity or
other ecosystem services.
The threats to biodiversity and
ecosystem services are most urgent in South America, Africa and parts of Asia. North
America and Europe are expected to have low conversion to crops and continued
reforestation.
Table SPM.1 lays out a long set of approaches
to achieve sustainability and possible actions and pathways for achieving them.
The list is not exhaustive, but rather illustrative, using examples from the
report.
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.
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
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.
a blight-resistant chestnut tree bred using traditional breeding techniques by The American Chestnut Foundation; photo by F.T. Campbell
Nearly one-third of the continental United States is covered by forests, more than 1 million square miles. As demonstrated by many authorities and – I hope! – in my blogs, these forests face increasing threats, including introduction of rising numbers of non-native insects and pathogens that kill or severely damage the tree species that comprise those forests.
One
response has been a request by the U.S. Endowment for Forestry and Communities,
the Environmental Protection Agency, and U.S. Department of Agriculture
(Agricultural Research Service, Animal and Plant Health Inspection Service,
U.S. Forest Service, and National Institute of Food and Agriculture) that the
National Academies of Sciences, Engineering, and Medicine consider the
potential for the use of biotechnology to mitigate these threats to forest
health.
The resulting report was released in January 2019 (see full citation at the end of the blog). The report is 240 pages long, very thorough, and wide-ranging. It does have a 12-page summary, listing the Panel’s many conclusions and its recommendations. While the preponderance of the report concerns forests on the North American continent, the panel did seek information about threats to endemic trees in Hawai`i, which (to my mind) are especially severe. See earlier blogs here and here.
To
me, one of the report’s most important conclusions is that while there are
multiple options for dealing with forest pests, their feasibility and success
vary widely. Saying that no single management practice is likely to be
effective by itself, the report calls
for increasing investment in the full range of strategies other than
biotechnology,i.e.,
preventing
arrival of non-native pests (recognized as the first line of defense and the
most cost-effective strategy);
site
management practices;
biocontrol;
and
enhancement
of genetic resistance naturally present in affected tree species (including developing human capital in professions related to tree
breeding).
The
panel was not asked to examine the potential for biotech to reduce threats to
forest health by altering the pests affecting North American tree species so it
does not do so.
Summarizing the
Threat
Citing
Aukema et al. 2010 and other sources,
the Academy panels reports that approximately 450 species of insects and at
least 16 species of pathogens have been introduced and have established in
continental U.S. forests. Of those, 62 insects and all of the pathogens are
determined to have a high impact. A USDA Forest Service study estimates that 81.3
million acres (about 7% of all forested or treed land in the U.S.) are at risk
of losing at least 25% of tree vegetation by 2027 due to insects and pathogens.
These pests are both non-native, introduced species and native pests that are spreading
to new regions as a result of climate change.
The
Academy panel notes that loss of a tree species can have cascading adverse
effects on the forest ecosystem and on the range of services it provides and
the values it represents to human populations.
Part A. The Technology for Trees
The
Academy panel was asked to assess the ecological, economic, and social
implications of deploying genetically engineered trees. The experts also were asked
to identify the knowledge needed to evaluate the ways such a tree might affect
the prospects for forest health. The analysis was to include social and
cultural impacts as well as impacts on forest and associated ecosystems –
including their structure, composition, processes, function, productivity, and
resilience.
This
use of biotechnology to restore healthy forests differs from applications in
industrial plantations or annual agricultural crops in that the biotech tree is
intended to proliferate in a natural forest setting.
The
authors chose four taxa — American chestnut (Castanea dentata), whitebark pine (Pinus albicaulis), ash (Fraxinus
spp.), and poplars (Populus spp.) —
to illustrate the variety of threats to forest health and efforts to date to
protect the resource.
The
committee defined forest health as:
A condition that sustains the structure,
composition, processes, function, productivity, and resilience of forest
ecosystems over time and space.
The
panel says that “forest health” is assessed based on current knowledge and is
influenced by human needs, cultural values, and land management objectives.
1. A Balanced
Analysis
The
report does not hype biotechnology for solving problems. The panel called for
research on even the foundational question: whether resistance imparted to tree
species through a genetic change will be sufficient to persist in trees that
are expected to live for decades to centuries as well as in the generations
they parent.
The
report compares the two approaches to enhancing genetic resistance to pests, i.e., selective (traditional) breeding
and relying on biotechnology. Both
involve multiple steps, expense, and risks of pursuing what ultimately turn out
to be dead ends.
Thus,
in traditional selective breeding, scientists must complete the following
steps:
1)
Determine whether genetic resistance exists within the affected tree species’
population. According to the Academy report, while many tree species have some
degree of resistance to particular native or non-native pests, finding suitable
parent trees can be difficult, and even when they are found, not all the
progeny will be resistant.
2)
Evaluate the durability of resistance in order to protect trees over decades.
3)
Propagate the resistant progeny in greenhouses or seed orchards to create
sufficient resistant genotypes for restoration and reforestation. Many tree
species are difficult to propagate using cell culture and regeneration.
In
applying biotechnology techniques, scientists must complete the following
steps:
1)
Identify the genes carrying pertinent traits – which are to be modified, introduced,
or silenced. Scientists don’t know what genetic mechanisms underlie important
traits. This discovery process is more difficult for tree species than for
agronomic crops due to the plants’ large size, long generation time, and (in
the case of conifers) immense genomes. Another problem is that forest trees
have high levels of heterozygosity due to their large population sizes and
outcrossing breeding systems, which complicates genome assembly and modification.
Still, recent technological improvements are making this identification process
easier.
2)
Insert the genes using various biotechnology tools such as transgenesis and
genome editing.
3)
Produce trees containing the desired gene sequence to
regenerate plants from disorganized callus tissue. As noted above, many tree species
are difficult to propagate using cell culture and regeneration. Even when this
approach is possible, the regeneration of a plant from a single cell may not
produce an individual that has the desired genetic change in every cell.
The
time line for applying either approach to protect forest health will depend on several
factors, including the biology of both the tree and the pest, and the
environments in which the target tree species exists. It can vary from a few
years to multiple decades.
2. Who Should
Carry Out Genetic Improvement of Trees (and by implication, all long-term
strategies to protect forest health)?
Trees
provide private as well as public benefits, such as income from timber sales. However,
the costs of developing a genetically resistant tree – whether achieved through
traditional breeding or biotechnology processes – will be incurred up front and
the benefits will follow later – often decades or even centuries later. Consequently,
the sponsors need a long time horizon!
The
panel suggests that the public sector can have greater patience when it
perceives that significant public benefits will be forthcoming. The private
sector is not likely to invest in the protection of forest health because it
cannot fully capture the benefits that may accrue. The authors define “public
sector” to include government agencies and non-profit organizations.
Part B. Impacts, Ethics, and Policy
1. Impacts
The
report provides careful analysis of the ecological impacts that should be
considered in evaluating the use of biotechnology to maintain or improve forest
health. The report emphasizes that if the modified trees are to spread and
restore the species to its role in the ecosystem, the modified trees must be
competitive in the ecosystem (while not being invasive!). The trees must be suited
to the variety of climates and other biophysical conditions found throughout
the tree species’ range. The report even said that establishing the rangewide
patterns of distribution of the target species’ natural standing genetic variation
should be researched before a project is begun aimed at inserting pest
resistance genes.
2. Public
attitudes and ethical considerations
The
panel was charged to consider social, cultural, and ethical issues related to
the potential use of biotechnology to develop trees resistant to pests. They
devote 13 pages to examining this complex set of issues, which range from
Native Americans’ use of black ash to concepts of “wildness” and competing
models of “conservation”. There have
been few surveys or other studies of Americans’ attitudes. The panel also notes
that the public lacks in-depth knowledge about genetic interventions and processes,
so their attitudes are likely to change — for or against use of the technology
— as they learn more or associate biotech with strongly held beliefs.
The
Panel notes that important ethical questions fall outside any current “impact
analysis” evaluation system, or any new analysis that focuses on “ecosystem
services”. It calls for additional research
on societal response to biotechnology applied to forest health and development
of new forms of engaging full range of stakeholders.
3. Need for a New
Impact Assessment Framework
The panel
concludes that the current regulatory system does not provide for consideration
of most aspects of forest health in assessing the safety of a tree developed
through biotechnology, including those described above. Consequently, the
panel calls for an entirely new assessment process in order to evaluate both
the ecological and social/ethical considerations.
The
long-standing Coordinated Framework for the Regulation of Biotechnology relies
on existing federal statutes. Under this system, the regulatory agencies (USDA Animal
and Plant Health Inspection Service, Environmental Protection Agency, sometimes
Food and Drug Administration) regulate specific products, not the process by
which the products are produced. For example, USDA regulates only the small
subset of biotech trees which were transformed via use of a bacterium, Agrobacterium tumefaciens, to insert the
desired trait.
The
panel says that an agency undertaking an environmental analysis under the terms
of the National Environmental Protection Act would need to add an analysis of
some components of forest health.
To rectify these analytical gaps, the panel suggests creation of an integrated impact assessment framework that combines ecological risk assessment with consideration of ecosystem services. This integrated framework would evaluate the effect of the pest threat – and responses to that threat – on forest processes –as well as on associated cultural and spiritual values. The impact assessment must make explicit the links between specific forest protections and their effects on important ecosystem services. The panel points to an EPA guidance document on economic impact analysis (see reference at the end of this blog) as a useful starting point. The panel suggests that this framework should be used to evaluate any forest health intervention, including use of selectively bred trees.
Because
of the length of time until tree reproductive maturity and long life span of
most trees, collecting data for an impact assessment might take years. The
panel suggests adopting a tiered system which would allow field trials of low-risk
transgenic trees to reach flowering stage so as to provide data on gene flow
and climatic tolerances – data that are essential for a proper impact
assessment that would evaluate the likelihood of ultimate success of the
restoration effort. Such experiments and
carefully developed models must also identify sources of uncertainty.
Adoption
of such a stepwise, iterative process
requires abandonment of the current regulatory system, which does not permit
the flowering of biotech trees in most cases.
My Conclusions
The
report makes clear several realities:
1)
the magnitude of the threat to our forests from non-native pests – which
warrants an effective response;
2)
the strengths and weaknesses of the several response strategies – none of which
can solve this problem in isolation;
3)
the scientific challenges that need to be overcome to apply strategies aimed at
enhancing tree species’ genetic resistance to pests;
4)
the need for greatly expanded programs to implement the various strategies.
Also, the report shows how unprepared our country is to systematically assess the full impacts of new forms of tree breeding and forest health. To rectify this gap, the report also calls for a complete overhaul of the procedures by which the government currently evaluates the environmental risks associated with applying one of the strategies, genetic transformation of the plant host – which is defined (in the Glosssary) as including transgenesis, cisgenesis, RNA interference, genome editing, and insertion of synthetic DNA.
The
recommended actions in this report – taken either individually or collectively
– require a level of commitment by government and conservation organizations
that far exceeds the current level.
I
hope the Academies’ prestige can prompt such commitment. For example,
development of a sufficiently robust coalition of groups could re-invigorate
our society’s response to the invasive pest threat. The report has received
some encouraging attention. It was reported in Nature and Scientific
American. About 130 people tuned in live to
the launch webinar on January 8th. So far, almost 1,200 people have
downloaded the report.
The
government shutdown has delayed the sponsoring agencies’ (USDA and EPA) official reactions to the report. It probably curtailed
some publicity efforts among all the sponsoring agencies. Also, the report will
be only one item in the overflowing inboxes of agency scientists and managers
after 35 days on furlough. I hope it won’t be lost, especially with the threat
of a second shut-down.
How
can those of us in the public who care about our forests ramp up our activity to
support these recommendations?
A reminder: Scott Schlarbaum and I addressed the need for a greatly expanded restoration component as part of a comprehensive response to non-native tree-killing pests in our report Fading Forests III, released five years ago. It is available here.
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
National
Academies of Sciences, Engineering, and Medicine. 2019. Forest Health and
Biotech: Possibilities and Considerations. Washington, DC: The National
Academies Press. doi: https://doi.org/10.17226/25221.
U.S.
Environmental Protection Agency. 2014. Guidelines for Preparing Economic
Analyses. Washington, D.C.
Prompted
by the rising number of Phytophthora-caused
diseases in forests on several continents, in 1999 the International Union of
Forest Research Organizations (IUFRO) formed the IUFRO Working Party 7.02.09
‘Phytophthora Diseases of Forest Trees’. Last spring This group published a
global overview of Phytophthora
diseases of trees (Jung et al. 2018; see
full citation at the end of this blog).
The
study covers 13 different outbreaks of Phytophthora-caused
disease in forests and natural ecosystems of Europe, Australia and the
Americas.
The
picture is alarming!
Jung et al. state definitively that the
international movement of infested nursery stock and planting of reforestation
stock from infested nurseries have been the main pathway of introduction and
establishment of Phytophthora species
in these forests.
The Picture: A
Growing List of Diseases, Species, and Places Affected,
Jung et al. note that, during the past six decades, the number of previously unknown Phytophthora declines and diebacks of natural and semi-natural forests and woodlands has increased exponentially. The vast majority of these disease complexes have been driven by introduced invasive Phytophthora species. In 1996, 50 Phytophthora species were known. In the 20 years since then, more than 100 new Phytophthora species have been described or informally designated. One study (Tsao 1990) estimated that more than 66 % of all fine root diseases and more than 90 % of all collar rots of woody plants are caused by Phytophthora spp. Many of these had previously been attributed to abiotic factors or secondary pathogens. One example – surprising to me, at least – is that decline of mature beech trees in Central Europe is linked to Phytophthora rather than beech bark disease!
Several
of the disease complexes described in Jung et
al. 2018 are causing heartrending destruction of unique floras, e.g., jarrah, tuart, and other
communities of western Australia and kauri forests of New Zealand. The authors expect
increasing damage to the Mediterranean maquis
in the future. They list these among other examples:
Ink disease of chestnuts worldwide
Oak declines and diebacks in Europe and North America
Decline and mortality of alders (Alnus species) in Europe
Decline and mortality of Port-Orford cedar (Chamaecyparis lawsoniana) in Europe and North America
Kauri dieback in New Zealand link to earlier blog
Decline and mortality of Austrocedrus chilensis and Juniperus communis in Argentina and Europe
Diebacks of natural ecosystems in Australia
Decline and dieback of the Mediterranean maquis vegetation
Decline and dieback of European beech in Europe and the US
Dieback and mortality of southern beech (Nothofagus species) in the United Kingdom and Chile
‘Sudden Oak Death’ and ‘Sudden Larch Death’ in the US and United Kingdom
Leaf and twig blight of holly (Ilex aquifolium) in Europe and North America
Needle cast and defoliation of Pinus radiata in Chile
Several
of the Phytophthoras are causing
severe damage on several continents:
P. cinnamomi in Europe,
North America, and Australia
P. austrocedri in South America,
Europe, and western Asia
P. ramorum in Europe and
North America
P. lateralis in North America
and Europe.
Often,
the genetic makeup of the Phytophtoras
species varies in these different locations. These differences indicate separate
introductions and the existence of sexual reproduction and continuing evolution
in response to conditions.
WhyPhytophthoras
are Spreading via the Plant Trade and Nursery Practices
First,
Phytophthora species are able to
survive unsuitable environmental conditions over several years as dormant
resting structures in the soil or in infected plant tissues. When environmental
conditions become suitable, the resting spores germinate – often prolifically. Since
visible symptoms might not appear for considerable time after infection because
the mechanism is progressive destruction of the fine root system, detection of
the disease is delayed, further undermining control.
Second,
most of the Phytophthora species causing
disease complexes were unnoticed as
co-evolved species in their native environment. Often they were unknown to
science before their introduction to other continents – where they become
invasive on naïve plant species. Consequently, these species are not captured
by the international plant health system, which is based on lists of recognized
“pest” species.
Third,
the common nursery practice of applying fungicides or fungistatic chemicals masks
the presence of pathogens – another way plants pass unnoticed through phytosanitary
controls. These chemicals do not, however, kill the pathogen.
Fourth,
the importation into receiving nurseries of plants from around the world
provides ample opportunity for the introduced Phytophthoras to hybridize. The interspecific hybrids may differ in
host range and virulence from the parent species, thus making predictions about
the potential effects of an ongoing invasion even more difficult.
Fifth,
the nurseries or plantings in gardens or restoration projects also provide suitable
environments for prolific germination and spread.
All
of these risks were first enumerated by the eminent British pathologist Clive
Brasier a decade ago! (See Brasier et al.
2008 citation at the end of the blog.)
As Jung et al. 2018 point out, the scientific community has repeatedly urged regulators to require the use of preventative system approaches for producing Phytophthora-free nursery stock (see references in the article). Scientists have provided research-based guidance to reduce the risk of infestation. Such measures are being implemented by only some nurseries in the US. For example, USDA APHIS has specific requirements for nurseries that ship hosts of P. ramorum in interstate commerce after the nurseries or the plants have tested positive. More broadly, APHIS, the states, and the nursery industry are in the second round of pilot testing of an integrated measures approach to managing all pests under the Systems Approach to Nursery Certification (SANC) program
At the international level, the International Plant Protection Convention has adopted ISPM#36, which also envisions greater reliance on systems approaches. However, the preponderance of international efforts to protect plant health continue to rely on visual inspections that look for species on a list of those known to be harmful. Yet we know that most damaging Phytophthoras were unknown before their introduction to naïve ecosystems.
Furthermore,
use of fungicides and fungistatic chemicals is still allowed before shipment.
As pointed out by several experts beginning with Dr. Brasier but including Liebhold et al. 2012, Santini et al. 2013, Jung et al. 2016, Eschen et al. 2017, this approach has failed to halt spread of highly damaging pathogens. (I note that the list of such pathogens is not limited to Phytophthoras; see the description of ohia rust in Hawai`i, Australia, and New Zealand).
Jung et al. 2018 also call for increasing the genetic resistance of susceptible tree species. The authors regard this as the most promising sustainable management approach for stabilizing declining natural ecosystems and for reintroducing susceptible tree species at sites with high disease impact. See my blogs about efforts to enhance U.S. tree-breeding posted earlier this year.
SOURCES
Brasier
CM. 2008. The biosecurity threat to the UK and global environment from
international trade in plants. Plant Pathology 57: 792–808.
Jung
T, Orlikowski L, Henricot B, et al.
2016. Widespread Phytophthora infestations in European nurseries put forest,
semi-natural and horticultural ecosystems at high risk of Phytophthora
diseases. Forest Pathology 46: 134–163.
Jung,
T., A. Pérez-Sierra, A. Durán, M. Horta Jung, Y. Balci, B. Scanu. 2018. Canker
and decline diseases caused by soil- and airborne Phytophthora species in forests
and woodlands. Persoonia 40, 2018: 182–220
Open Access!
Liebhold
AM, Brockerhoff EG, Garrett LJ, et
al. 2012. Live plant imports: the major pathway for forest insect and
pathogen invasions of the US. Frontiers in Ecology and Environment 10: 135–143.
Santini
A, Ghelardini L, De Pace C, et al.
2013. Biogeographic patterns and determinants of invasion by alien forest
pathogens in Europe. New Phytologist 197: 238–250.
Tsao
PH. 1990. Why many Phytophthora root rots and crown rots of tree and
horticultural crops remain undetected. Bulletin OEPP/EPPO Bulletin 20: 11–17
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.
Last month, in my blog about the US Geological Survey’s report on invasive species I announced release of a report by South Africa on its invasive species management programs – available here. Because this report is unusual in both its rigor and its honesty, I’m returning to it here. I think it is a model for our country and others.
The report provides the basics. That is, it analyzes pathways of introduction and spread; number, distribution and impact of individual species; species richness and abundance of alien species in defined areas; and the effectiveness of interventions. Of the 775 invasive species identified to date, 556, or about 72%, are listed under some national regulatory program. Terrestrial and freshwater plants number 574 species; terrestrial invertebrates number 107 species. A different set of 107 species, or about 14%, are considered by experts to be having major or severe impacts on biodiversity and/or human wellbeing. The highest numbers of alien species are in the savanna, grassland, Indian Ocean coastal belt, and fynbos biomes. South Africans are particularly focused on the reductions in surface water resulting from plant invasions. Much of the control effort is under the egis of the decades-old “Working for Water” program.
Also, the report has features that are all-too-rare in work of its kind. First is the authors’ focus on rigor – of data sources and interpretation of those data using standardized criteria. Second – and even more important – is their call for analyzing the efficacy of the components of invasive species program. They insist on the need to measure outcomes (that is, results), not just inputs (resources committed) and outputs (“acres treated”, etc.). Inputs are far easier to measure and are, unfortunately, the mainstay of how most U.S. efforts are tracked – if they are tracked at all.
As they note, measure of inputs and outputs are not useful because they provide no guidance on the purpose of the action or treatment or of its effectiveness in achieving that purpose.
(For earlier CISP advocacy of measuring outcomes, visit the National Environmental Coalition on Invasive Species and read the bullet points under “Recommendations for a Comprehensive National Response”.)
The report has been praised by international conservationists, including Piero Genovesi – chair of the IUCN’s Invasive Species Specialist Group. British ecologist Helen Roy says that, to her knowledge, it is “the first comprehensive synthesis of the state of invasive species by any country.”
How well are programs working?
The authors’ focus on rigor includes being scrupulously honest in their assessments of current program components. They note deficiencies and disappointments, even when the conclusions might be politically inconvenient. To be fair, all countries struggle to achieve success in managing bioinvasions. And South Africa is, in many ways, a developing country with a myriad of economic and social challenges.
So it is probably not surprising that, for most factors analyzed, the authors say data are insufficient to determine the program’s impact. Where data are adequate, they often show that programs fall short. For example, they conclude that control measures have been effective in reducing populations of established invasive species, usually plants, in some localized areas but not in others. While the situation would arguably have been worse had there been no control, current control efforts have not been effective in preventing the ongoing spread of IAS when viewed at a national scale. Only one of South Africa’s 72 international ports of entry has consistent inspection of incoming air passengers and cargo – and even those inspections are not carried out outside of regular working hours (e.g., nights and weekends).
The authors are even critical of the “Working for Water” program – which is the basis for most control efforts in South Africa and enjoys wide political support. WfW has two goals: providing employment and development opportunities to disadvantaged individuals in rural areas, and managing invasive alien plants. Despite substantial funding, the WfW program has supported control teams that have reached only 2% – 5% of the estimated extent of the most important invasive plants. Furthermore, programs structured to provide employment have not ensured use of the most efficient control strategies.
What’s needed in South Africa — and around the world
The authors conclude that South Africa needs new processes to monitor and report on bioinvasions in order to achieve evidence-based policy and management decisions. They call for (1) more research to determine and assess invasive species impacts; (2) better monitoring of the effectiveness of current control measures; and (3) the development of methods to look at the impact of bioinvasions and their management on society as a whole.
The authors say it is important for South Africa to improve its management of invasive species because their impacts are already large and are likely to increase significantly. They note that improving management efficiency will require difficult choices and trade-offs. They recommend a focus on priority pathways, species, and areas. They also stress return on investment.
I don’t know how this report has been received in South Africa. I hope government officials, media observers, landowners, political parties, and other stakeholders appreciate the honesty and expertise involved. I hope they take the analyses and recommendations seriously and act on them.
(Preparation of the report was was overseen by a team of editors and contributing authors employed by the South African National Biological Diversity Institute (SANBI) and the DST-NRF Centre of Excellence for Invasion Biology at (C.I.B). Drafts were widely circulated to contributing authors and other stakeholders for comments. An independent review editor will be appointed to assess the review process and recommend any ways to strengthen the process for future reports.)
Meanwhile, how do we Americans apply the same rigor to analyzing our own efforts?
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.
Several scientists at the United States Geological Service (USGS) have published a report and accompanying datasets that attempts to provide a publicly accessible and comprehensive list of non-native species established in United States.
Led by Annie Simpson and Meghan C. Eyler, a team of six scientists worked six years (2013–2018). They reviewed 1,166 authoritative sources to develop a list of 11,344 unique names – most of them binomials (genus and species), a few genera, plus some viruses.
This was a Herculean effort that produced very valuable products. We are all in their dept!
Simpson and Eyler point out that knowing which species are non-native to a region is a first step to managing invasive species. Lists compiled in the past were developed to serve a variety of purposes, including watch lists for preventing invasions, inventory and monitoring lists for research and modeling, regulatory lists for species control, and non-regulatory lists for raising awareness. As a result, they are not comprehensive.
Among the sources these authors consulted in preparing the list were peer-reviewed journal articles, books, brochures, circulars, databases, environmental assessments, technical reports, graduate theses, and websites.
Data – by Region
The report also notes which non-native species were established in each of three regions: the “lower 48” states, Alaska, and Hawai`i. Not surprisingly, more than half the non-native taxa are established in the vast area (nearly 7.9 million km2) comprising the “lower 48” states – 6,675 taxa. Almost half of the total number of non-native taxa have established in the tiny geographic region (only 28,311 km2) of Hawai`i – 5,848 taxa. One-tenth as many non-native taxa – 598 – are reported as established in Alaska (1.7 million km2).
This report includes taxa that are not native to any part of the specific region, but established (naturalized) somewhere in the region. An “established” species must have at least one population that is successfully reproducing or breeding in natural systems. The list includes domesticated animals and plants introduced for crops or horticulture when the taxon has escaped cultivation or captivity and become established in the wild. Species listed range from feral hogs (Sus scrofa) to plum pox virus and citrus canker to ohia rust (Puccinia psidii).
Of the total 11,344 taxa, 157 are established in all three regions. These included 125 vascular plants (especially grasses and asters); 13 arthropods, 11 mammals; 6 birds; 3 mollusks; 1 bryozoan. One of the ubiquitous plant species is tree of heaven (Ailanthus altissima). I find it entirely appropriate that the cover photo shows this tree – the photo was taken 8 miles from my home in Fairfax County, Virginia.
Nearly three-quarters (71.4%) of the non-native species in Alaska are plant species. More than half (59.7%) of the non-native species in the “lower 48” region are also plants. Nearly all the remainder of the non-native species in both regions are some kind of animal. Fungi constitute only 1.8% of the non-native species in the “lower 48” region; all the rest of the groups (Bacteria, Chromista, Protozoa, Virus) constitute less than 1% of the non-native species recorded in either region.
By contrast, in Hawai`i, animals make up 69.7% of the listed non-native species; most are invertebrates. Plants constitute 29.8% of the Hawaiian list.
Gaps, by Taxon
The authors recognize that invertebrates and microbes are under-represented because species are still being discovered; non-charismatic and difficult-to-identify species tend to be overlooked; and the species composition of any nation in this era of globalization is constantly subject to change.
I have noted some gaps among the pathogens: the absence of some of the Phytophthora that have been detected infecting shrubs and herbaceous plants in California, e.g., Phytophthora cambivora, siskiyouensis, tentaculata; and the “rapid ohia death” pathogens, Ceratocystishuliohia and C. lukuohia. Dr. Simpson is aware of these gaps and is soliciting sources to help add these organisms – especially the various Phytophthora species – to the next version of the list.
Simpson and Eyler note that the relative geographic distribution of the list at its current state seems to reinforce three well established premises: that tropical island systems are particularly vulnerable; that higher latitudes host fewer but are not invulnerable; and that species diversity in general decreases with increasing latitude.
Comparisons to Other Databases
After standardizing the names in the list by comparing them to the Integrated Taxonomic Information System (ITIS), Simpson and Eyler also reviewed the USGS BISON database, which has more than 381 million occurrence records for native and non-native species in the U.S. and Canada, covering 427,123 different taxa. (The BISON database contains significantly more species occurrences for the U.S. than the largest invasive species database, EDDMapS, which contained 4.4 million species occurrences as of June 2018.) Simpson and Eyler had to evaluate which of these taxa met their definition of non-native, since most species occurrence records in the USGS BISON are not labeled as non-native in the original records.
Comparing the BISON and non-native lists, Simpson and Eyler found that the BISON list contained a larger number of occurrence records for non-native taxa: a total of 13,450,515.However, the BISON list does not provide complete coverage of non-native species: it includes records for 77% of list of non-native species Simpson and Eyler found in Alaska, 75% of the “lower 48” sublist, but only 37% of the Hawaiian sublist.
Simpson and Eyler state their intention to continue updating the list of non-native species, they welcome contributions to it from area experts, and they urge integration of new occurrence data into invasive species database such as EDDMapS.
Indicators of Non-Native Species Richness
Figure 3 in the report (above) maps the number of non-native taxa in BISON at the county level. Figure 4 displays the proportion of non-native to native species in BISON. Higher percentages are generally evident in coastal areas and other regional hotspots. For example, the proportion in Hawaiian counties is greater than 33%. Additional data are needed to perform a more in-depth analysis of non-native species richness and abundance.
UPDATE! New Report in the Works
In June 2021, USGS announced that it was updating its Comprehensive List of Non-Native Species Established in 3 Major Regions of the U.S. so that the document more closely aligns with the parameters of the Global Register of Introduced and Invasive Species. The new USGS dataset is to be called the US Register of Introduced and Invasive Species. The list in the current draft includes 15,364 records. About 500 of these records are in Alaska, 6,000 in Hawai`i, and 8,700 in the conterminous 48 States.
One of the lead authors, Annie Simpson, contacted invasive species experts seeking feedback and suggested additions – based on authoritative resources such as peer reviewed journal articles, pest alerts, databases, books, and technical bulletins.She sought input by 25 July, 2021.
The published version of this dataset will be made freely available on USGS’ ScienceBase (https://www.sciencebase.gov), and all reviewers will be acknowledged in the dataset’s abstract.
SOURCE
Simpson, A., and Eyler, M.C., 2018, First comprehensive list of non-native species established in three major regions of the United States: U.S. Geological Survey Open-File Report 2018-1156, 15 p.
The report and accompanying data tables are available here.
South African report
In an unrelated but similar development, South Africa has issued a report on its invasive species — 2017 The Status of Biological Invasions and Their Management in South Africa. The report analyzes pathways of introduction and spread; number, distribution and impact of individual species; species richness and abundance of alien species in defined areas; and the effectiveness of interventions. The report notes that 775 invasive species have been identified to date, of which 556 are listed under some national regulatory program. Terrestrial and freshwater plants number 574 species; terrestrial invertebrates number 107 species. (This total does not include the polyphagous shot hole borer, which was detected too recently.) 107 species are considered by experts to be having either major or severe impacts on biodiversity and/or human wellbeing. Alien species richness is highest in the savanna, grassland, Indian Ocean coastal belt and fynbos biomes, lower in the more arid Karoo and desert biomes. South Africans are particularly focused on the reductions in surface water resulting from plant invasions. The decades-old “Working for Water” program has two goals: providing employment and development opportunities to disadvantaged individuals in rural areas, and managing invasive alien plants.
The Status of Biological Invasions and Their Management in South Africa is available 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.
While I usually blog about insects (and plant pathogens) that have invaded new ecosystems and are killing native plant species, I am aware that insects are numerous and vitally important components of the ecosystems in which they evolved. I join others in noting with concern evidence that insect populations in wide-apart areas have declined at very high rates. Insects appear to be affected by the Sixth Extinction Event (concept described here and here) as much as or possibly more than various vertebrate and plant taxonomic groups.
The Zoological Society of London and World Wildlife Fund published this week the 2016 version of the Living Planet report. Based on an analysis of 3,700 vertebrate species (birds, fish, mammals, amphibians and reptiles), the authors concluded that global wildlife populations have fallen by 58% since 1970 (Morelle; see references at the end of the blog).
Dirzo et al. in 2014 provided a very interesting discussion of the impacts of species’ declines in numbers and local extinctions – short of complete extinction. They asserted that “declines in numbers of individuals in local populations and changes in the composition of species in a community will generally cause greater impacts on ecosystem function than global extinctions. Dirzo et al. noted the importance of invertebrates, especially insects, in ecosystem functioning. They stated that the smaller fauna – including insects – “arguably are more functionally important” than charismatic megafauna and called for improved monitoring and study of such taxa, particularly invertebrates,
In their study, Dirzo et al. estimated that, since 1970, Lepidoptera – an order containing many important pollinators – had declined 35% in abundance globally over 40 years. Declines of other insect orders were considerably more. One study they cited found an overall 45% decline for all invertebrate populations over 35 years. More recent studies find decline rates that considerably exceed the estimated decline of 58% in global abundance of wild vertebrates over a 42-year period (Morelle; Hallmann et al.)
A year ago, Hallmann et al. reported a 76% decline in the biomass of flying insects over a 27-year period in Germany. There were seasonal variations; in midsummer, when insect biomass is highest, the decline was 82%. The study was carried out in nature protection areas – that is, places set aside and protected to conserve biological diversity. Hallmann et al. predict cascading effects on food webs and jeopardy to ecosystem services, including pollination, herbivory and breakdown of detritus, nutrient cycling and providing a food source for higher trophic levels such as birds, mammals and amphibians.
Hallmann et al. said that changes in weather, land use, and habitat characteristics could not explain this overall decline. Declines occurred in both nutrient-poor habitat types (e.g., heathlands, sandy grasslands, and dunes) and nutrient-rich habitats (grasslands, margins and wasteland), as well as in pioneer and shrub communities.
Another of the few studies looking at insects broadly, a study of flying insect biomass in the United Kingdom, found a biomass decline at only one of the four sites. Hallmann et al. note that the British researchers used considerably different sampling methods that targetted primarily high-flying insects (and caught mostly members of one fly family) whereas their own Malaise traps caught insects flying close to the ground and a much wider diversity of taxa.
Taxon-specific studies have also found severe declines in insect populations.
Hallmann et al. concluded that the scale of decline in insect biomass – throughout the growing season, and irrespective of habitat type or landscape configuration – suggest that large-scale factors must be involved. As noted, their data did not support either landscape changes or climate change as explanatory factors – although they admit that they did not exhaustively analyze the full range of climatic variables that could potentially impact insect biomass. Hallmann et al. did think that agricultural intensification (e.g. pesticide usage, year-round tillage, increased use of fertilizers and frequency of agronomic measures) was a plausible cause of insect biomass decline given the reserves’ limited size in typically fragmented western-European landscapes. The noted that the protected areas might serve as insect sources which might be counterbalanced by the surrounding agricultural fields, which might act as sinks or ecological traps.
While Hallman et al. did not specify the types of pesticides being used by the German farmers operating near their study areas, in recent years there has been growing concern about widespread use of neonicotenoids, which appear to pose a threat to bees and possibly other insects. Three sources of information are the European Food Safety Agency; Xerxes Society; and petition pertaining to regulation of seeds treated by neonicotenoids submitted by the Center for Food Safety.
This month, Bradford Lister and Andrés García published a study that compared numbers of the insects and insectivores (birds, frogs, lizards) in Puerto Rico’s tropical rainforest in 2012 to results of Lister’s studies there in 1976 and 1977. Overall arthropod biomass in Puerto Rico’s Luquillo rainforest fell 10 to 60 times since 1970s (Lister and Garcia). Numbers of insects in the vegetation collected by sweep nets decreased to a fourth or an eighth of what they had been. The catch rate of ground-dwelling arthropods caught in sticky traps fell 60-fold (Guarino).
Lister and Garcia attribute the crash in arthropod numbers to climate change, especially rising maximum temperatures. They note that over the same 40-year period, the average high temperature in the rainforest increased by 4 degrees Fahrenheit (2oC). Lister and Garcia cite several studies indicating that tropical invertebrates are adapted to a narrow band of temperatures.
Lister and Garcia also measured declines among insect-feeding vertebrates. The biomass of anole lizards dropped by more than 30%. Some anole species disappeared from the interior forest (Guarino). Declines in number of coqui frogs (Eleutherodactylus spp) began in the 1970s. Currently, three of 16 species are extinct, and the remaining 13 species are classified in some category of endangered or threatened. Disease caused by the fungus Batrachochytrium dendrobatidis is not a factor at the elevations where study done.
Anolis gundlachi; photo by Joe King
Citing data from other researchers, Lister and Garcia report that numbers of insectivorous birds captured in mist nets fell 53% between 1990 and 2005.
Lister and Garcia sought to explain why there were simultaneous, long-term declines in arthropods, lizards, frogs, and birds over the past four decades in the relatively undisturbed rainforests of northeastern Puerto Rico. They concluded that climate warming has been a major factor driving reductions in arthropod abundance, and that these declines have in turn precipitated decreases in forest insectivores in a classic bottom-up cascade.
As supporting evidence, Lister and Garcia cite
(1) Declines across varied species and communities that occurred in parallel with rising temperatures.
(2) Simultaneous declines of all arthropod taxa in their own and others’ studies – pointing to an overriding environmental factor that has had ubiquitous, adverse effects on forest arthropods regardless of taxonomic affiliation, stratum occupied, or type of niche exploited.
(3) Declines in arthropod abundance that occurred despite major decreases in their predators – and, presumably, reduced predatory pressure..
Lister and Garcia note that there have been almost no significant human perturbations in the Luquillo forest since the 1930s, and that pesticide use in Puerto Rico fell nearly 80% over the past 40 years with the decrease in agricultural activity on the island. Some of the insect trend data came from studies carried out in the Luquillo Long Term Ecological Study site.
Lister and Garcia say that major weather perturbations have also had an impact. Over the 36-year time span, there have been five major hurricanes and eight severe droughts. They note that the island’s vegetation regenerated rapidly after hurricanes Hugo and Maria; insect populations regenerated rapidly after Hurricane Georges. La Niña episodes led to an immediate increase in the abundance of canopy invertebrates, whereas El Niño episodes caused declines.
Of course, some insects are under threat from loss of their primary food plants to invasive species. I note particularly the Palamedes swallowtail butterfly (Papilio palamedes), which depends on redbay and swamp bay, and an estimated 21 species of North American butterflies and moths believed to specialists or largely dependent on ash.
In some cases, e.g., hemlock woolly adelgid and Asian longhorned beetle, neonicotenoids, specifically imidacloprid, is an essential tool to controlling a tree-killing invasive insect.
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.
SOURCES
Dirzo, R., H.S. Young, M. Galetti, G. Ceballos, N.J. B. Isaac, B. Collen. 2014. Defaunation in the Anthropocene. Science 345, 401
Guarino, B. 2018. ‘Hyperalarming’ study shows massive insect loss. 2018. The Washington Post October 15 2018
Hallmann CA, Sorg M, Jongejans E, Siepel H, Hofland N, Schwan H, et al. 2017. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoS ONE 12 (10): e0185809. https://doi.org/10.1371/journal. pone.0185809
Lister, B.C. and A. Garcia. 2018. Climate-driven declines in arthropod abundance restructure a rainforest food web. Proceedings of the National Academy of Sciences. http://www.pnas.org/content/early/2018/10/09/1722477115
The polyphagous shothole borer (PSHB) and its fungal symbiont Fusarium euwallaceae are killing trees in South Africa as well as in California.
Erythrina humeana in the Manie van der Schijff Botanical Garden, Pretoria
The pest complex’s presence was detected in August 2017 through an international sentinel tree program – the first detection of a tree pest under the program. Under the ‘sentinel plantings’ program, staff at botanical gardens and arboreta monitor their holdings – often exotic species growing outside of their natural range – and alert program partners when they detect damage caused by insects or pathogen not previously known to pose a risk. The International Plant Sentinel Network (IPSN) was launched in 2013. Botanical gardens and arboreta in South Africa joined the international effort in 2016 (Paap et al. 2918 – see list of sources at the end of this blog).
PSHB-caused tree mortality was initially detected in the KwaZulu-Natal National Botanical Gardens in Pietermaritzburg in August 2017. Affected trees were London Plane (Platanus x acerifolia) (Paap et al. 2018).
A beetle collected in 2012 in Durban, 50 km away from Pietermaritzburg, has now been determined to belong to the Euwallacea fornicatus species complex – indicating that the invasive insect and fungal species have been established in South Africa for several years (Paap et al. 2018). [Interestingly, 2012 is also the year that Dr. Akif Eskalen detected PSHB in a backyard avocado in southern California – setting off the detection, research, and slow-the-spread efforts now under way there.]
locations of PSHB detections in South Africa; map from http://polyphagous-shot-hole-borer.co.za/
South African authorities were immediately concerned because the beetle-fungus complex attacks such a broad range of trees (species in 58 plant families). Hosts include several species native to southern Africa – including cabbage tree (Cussonia spicata), common calpurnia (Calpurnia aurea), monkey plum (Diospyros lycioides), two species of coraltree (Erythrina humeana and E. lysistemon), huilboerboon (Schotia brachypetala), honey flower (Melianthus major), two alders (Cunonia capensis and Nuxia floribunda), and red orchid bush (Bauhinia galpinii). Also at risk are several commercial crop trees such as avocado (Persea americana), macadamia nut (Macadamia integrifolia), pecan (Carya illinoinensis), peach (Prunus persica), orange (Citrus sinensis) and grapevine (Vitis vinifera) and several ornamentals, including maple, holly, wisteria, oak and Camellia (Paap et al. 2018).
South Africa is home to a highly unique flora. Indeed, the “Cape Floral Kingdom” is the smallest of the six floral regions on Earth. For more about South Africa’s botanical importance, go here or here.
Rapid spread of the beetle-fungus complex appears likely because one of the most important reproductive hosts, castor bean (Ricinus communis) is a widespread woody weed in the KwaZulu-Natal region (Paap et al. 2018).
By July 2018, it was clear that PSHB was established in several parts of the country (see map). In George — a city along the southern coast, due east of Capetown, the beetle and fungus are affecting a wide range of indigenous and exotic trees in the botanical garden and the region‚ including box elder‚ Chinese and Japanese maple‚ oak‚ plane trees‚ Kapok trees‚ paper bark acacia‚ wild plum‚ dwarf corral and common corral (Chambers 2018).
In Johannesburg, a concerned citizen tracking the pest complex’ spread thinks that the beetle-fungus combination has already infested well over 100,000 of Johannesburg’s trees and is on track to damage or kill millions more (there are an estimated 6 – 10 million trees in Johannesburg, nearly all exotic) (Weltz 2018).
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.
SOURCES
Chambers, D. “A 2mm beetle is laying waste to George’s trees” Sunday Times. 30 May 2018 https://www.timeslive.co.za/news/sci-tech/2018-05-30-a-2mm-beetle-is-laying-waste-to-georges-trees/
Weltz, A. Beetle Mania The Nasty Insect that is Killing the Trees of Johannesburg. Yale Environment 360; Published at the Yale School of Forestry and Environmental Studies. https://e360.yale.edu/features/beetle-mania-the-nasty-insect-that-is-killing-the-trees-of-johannesburg
In May I blogged about adoption by the House of Representatives of its version of the Farm Bill, which will govern a wide range of policies for the next five years. I reported that the bill included weakened versions of a provision CISP has been seeking to establish programs to support long-term strategies to counter non-native, tree-killing insects and pathogens, e.g., biocontrol and breeding of trees resistant to pests.
I also reported that the House Farm bill contains provisions to which there is significant opposition from the larger environmental community. Several would gut some of our country’s fundamental environmental laws which have protected our health and natural resources since the early to mid-1970s. These provisions would:
Allow the U.S. Forest Service and the Interior Department’s Bureau of Land Management to decide for themselves whether an activity might “jeopardize” an endangered species (eliminating the need to consult with the U.S. Fish and Wildlife Service or National Marine Fisheries Service) (Section 8303 of the House Bill);
Allow the U.S. Forest Service and Bureau of Land Management to avoid preparing an environmental assessment under the National Environmental Policy Act (NEPA) for a long list of actions which currently must be assessed. That is, they could claim a “categorical exclusion” when taking a wide variety of “critical” actions aimed at addressing several goals. These include countering insect and disease infestations, reducing hazardous fuel loads, protecting municipal water sources, improving or enhancing critical habitat, increasing water yield, expediting salvage of dead trees following a catastrophic event, or achieving goals to maintain early successional forest. These “categorical exclusions” would apply to projects on up to 6,000 acres. (Sections 8311 – 8320); and
Require the EPA Administrator to register a pesticide if the Administrator determines that the pesticide, when used in accordance with widespread and commonly recognized practices, is not likely to jeopardize the survival of a species listed under the Endangered Species Act or to alter critical habitat. That is, the Administrator would not be required to consult with the U.S. Fish and Wildlife Service or National Marine Fisheries Service when making such determinations unlike under current law. (Section 9111).
The Senate passed its version of the Farm Bill in late June. Unfortunately, the Senate bill does not include the long-term restoration program CISP seeks. However, it doesn’t include the above attacks on environmental laws, either.
With the current Farm Bill set to expire on September 30th, there is considerable pressure to adopt a final version soon. House and Senate staffers have been meeting to find common ground. Representatives and Senators who are on the joint Conference Committee – charged with working out the final bill – will hold their first meeting next week, on September 5th.
In preparation for the meetings of the Conference Committee, 38 Senators have written to their two colleagues who will lead the Senate conferees. Their letter voices strong opposition to changing long-standing environmental law:
“These harmful riders, spread throughout the Forestry, Horticulture, and Miscellaneous titles of the House bill, subjected the legislation to unnecessary opposition on the House floor and now complicates [sic] the bipartisan cooperation needed to pass a final conference report.
Again, we write to express our strong opposition to gutting bedrock U.S. environmental and public health protections with provisions that threaten our air, water, lands, and wildlife.”
If your Senators signed the letter, please email, call, or write to thank them immediately. If your Senators didn’t – please urge them to express their support for its content.
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.
Ailanthus altissima
