June 2018 – Center for Invasive Species Prevention

New science reveals that threats remain from Bd, the infamous frog and toad-killing pathogen

California red-legged frog

courtesy of the U.S. Fish and Wildlife Service

In my last blog, I addressed how the United States Fish and Wildlife Service (FWS) has neglected to undertake the plan that it announced in early 2016 to finalize and improve its weak “interim” regulation aimed at preventing the salamander disease “Bsal” (Batrachochytrium salamandrivorans) from infecting salamanders in the still-unexposed United States. While Canada, the European Union and the United Kingdom have all taken very strong measures this year to block salamander imports that are not “Bsal free,” our country is stuck on a much weaker approach that I described as “Swiss cheese”.

Further compounding my concern about FWS’s inaction is new science about Bsal’s older devastating cousin, “Bd” (Batrachochytrium dendrobatidis), the separate fungus epidemic that has extirpated huge numbers of frogs and toads worldwide, driving several species extinct. Within the last year, the FWS has secretly withdrawn its consideration of a formal petition to regulate Bd filed with the Secretary of the Interior (in charge of the FWS) by Defenders of Wildlife in 2009. The Petition set out a plan to block the ongoing risk to native frogs and toads that the Bd pathogen posed then – and still poses. See description and documents under “Chytrid Fungus – September 16, 2010” here. The petition requested the FWS to create a “Clean Trade” program for shipments of imports, keeping them out of the country unless accompanied by certification that they are “Bd free” – whether by quarantine, testing or other reliable certification approach.

The new key paper, published last month in Science, is a sweeping study that finally answers the two questions that bedevilled amphibian experts since Bd’s first identification back in the mid-1990s: where did it come from and how was it spread around the world? O’Hanlon et al.’s study, “Recent Asian origin of chytrid fungi causing global amphibian declines,” here, [one must have an account to read the article] was extremely complex (there were 59 co-authors!). They discovered that Bd originated in salamanders in Asia, likely on the Korean Peninsula, and was spread via trade in live frogs and toads (pets, specialty foods and perhaps other uses). Genetic analysis of the numerous Bd strains showed there is still potential for more strains to mix, for new hybrids to emerge and for still more virulent outbreaks of the disease to occur. The article states: “… further sampling across this region is urgently needed because the substantial global trade in Asian amphibians presents a risk of seeding future outbreak lineages.” One lead co-author, Professor Matthew Fisher of Imperial College London, told the BBC:

“Until the ongoing trade in infected amphibians is halted, we will continue to put our irreplaceable global amphibian biodiversity recklessly at risk.”

Also notable is University of Maryland Professor Karen Lips’ concise commentary on it here [one must have an account to read the article]. Dr. Lips links the lessons of Bd and Bsal, pointing out the obvious: regulators need to learn the tragic lessons of Bd and take steps to keep out Bsal now – and not wait until after the fact of an outbreak.

Perhaps it was understandable before the O’Hanlon et al. paper that the FWS never responded to the Defenders of Wildlife Bd petition seeking trade restrictions because Bd was already so widespread within the United States then (unlike Bsal) and Bd’s origins and genetics were so confusing. It was not entirely clear that regulating further amphibian imports would have actually improved our level of Bd protection. But, O’Hanlon et al. changes that –– we now know enough to justify much stricter regulation to prevent more imports of Bd-infected frogs and toads and to block the potential for more virulent outbreaks here.

In short, FWS action on that 2009 Defenders of Wildlife petition is called for now. (Disclaimer: I wrote and filed that petition when I was Director of International Conservation at Defenders.) However, in a remarkably unfortunate use of its administrative powers, the FWS internally determined in March of 2017 to just altogether stop considering it. Rather than communicating back to Defenders that it is granting or denying its petition the FWS now states that it has “Withdrawn” consideration of any regulatory action, here.

This move by FWS plainly is part of the Trump Administration’s broad de-regulatory agenda. But, the FWS made no decision other than to put it on hold and Defenders of Wildlife did not withdraw it, so as a legal matter the nine-year old Petition is still pending. The FWS can and should take it up again and grant it. But, Defenders likely will have to push hard in order for that to happen.

The scientific community working on both Bd and Bsal has produced authoritative, painstaking studies on which the FWS and others can rely in regulating. And the community has made clear calls to stop the ongoing trade in many scores of species of amphibians around the world with no quarantines or health certificates, which is “business as usual” now. If the amphibian trade continues in the future it needs to be Clean Trade or we will suffer further consequences. It is up to us in the conservation community to convert the scientists’ calls into regulatory reality.

Posted by Peter Jenkins

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Study finds “targetted” phytosanitary measures are effective in reducing introductions of plant pests

Figure 2 from the article:

The number of new pathogens discovered each year on 131 focal host plant species in New Zealand (closed circles) and the mean annual rate of pathogen arrival estimated from the model (solid blue line), with shading showing the 95% credible interval.

Benjamin A. Sikes and several coauthors (article available here; open access!) find that targetted biosecurity programs can reduce the establishment of nonnative pathogens even while global trade and travel continue to increase.

The study relies on data from New Zealand because that country has more than 150 years of data on phytosanitary policies and pathogen introductions. Do other countries have data that would support a comparative study in order to test the authors’ conclusions more generally?

The study is unusual in analyzing introductions of a variety of forms of pathogens (fungi, oomycetes, and plasmodiophorids) rather than invertebrates. Pathogens pose significant plant health risks but are notoriously difficult to detect. The study used data on plant-pathogen associations recorded in New Zealand between 1847 and 2012. It focused on hosts in four primary production sectors: crops (46 species, including wheat, tomatoes, and onions); fruit trees (30 species, including grapes, apples, and kiwifruit); commercial forestry (42 species, including pines and eucalypts); and pastures (13 species of forage grasses and legumes). In total, 466 pathogen species for which the first New Zealand record was on one of these 131 host plants were included in the study. The pathogens were assumed to have arrived on imports seeds or fresh fruits of plants in the same family as the 131 hosts in the various production sectors.

After calculating each pathogen’s probable date of introduction, the authors compared those dates to contemporaneous levels of imports and incoming international travellers. Sikes et al. applied statistical techniques to adjust their data to the fact that detection of pathogens is particularly sensitive to variation in survey effort.

Findings:

The annual arrival rate of new fungal pathogens increased exponentially from 1880 to ~1980 in parallel with increasing import trade volumes. Subsequently rates stabilized despite continued rapid growth in not only imports but also in arrivals of international passengers.
However, there were significant differences among the four primary production sectors.

Arrival rates for pathogens associated with crops declined beginning in the 1970s but slightly earlier for those associated with pasture species. These declines occurred despite increasing import volumes.
Arrival rates of pathogens that attack forestry tree species continued to increase after 1960.
Arrival rates for pathogens that attack fruit tree species remained steady while import volumes rose steadily

Sikes et al. attribute these contrasting trends between production sectors to differences in New Zealand’s biosecurity efforts. They record when phytosanitary restrictions targetting the four sectors were adopted and link those changes to reductions in numbers of pathogens detected a decade or so later. They conclude that targetted biosecurity can slow pathogen arrival and establishment despite increasing trade and international movement of people.

Regarding the contrasting situation of the forestry and fruit tree sectors, Sikes et al. note that while phytosanitary inspections of timber imports was initiated in 1949, it focussed primarily on invertebrate pests. In addition, surveys for pathogens on fruit tree and forestry species were less robust than in the cases of crop and pasture species, and the peak survey effort occurred several decades later – in 1980 for fruit trees, 2000 for forestry species.

Furthermore, pathogens of forestry and fruit tree species can be introduced on types of imports other than seeds and fresh fruits, including soil and live plant material (e.g., rootstock) and untreated wood products.

Sikes et al. say there is no evidence of slowed pathogen arrival rates resulting from imposition of post-entry quarantine to live plant material beginning in the 1990s. I find this very troubling. Post-entry quarantine is a high-cost strategy. Still, several plant pathologists have advocated adoption of this strategy because they believed it would be sufficiently more effective in preventing introductions of – especially! – pathogens as to be worthwhile. Do others have data with which to add to our understanding of this disturbing phenomenon?

The authors suggest that introductions of tree-attacking pathogens on rising imports of wood packaging might have swamped decreases in introductions via other vectors. They consider that implementation of International Standard for Phytosanitary Measures (ISPM) No. 15 in 2002 means it is too early to see its impact in detection data. As I have blogged several times, implementation of ISPM#15 by the United States, at least, has reduced presence of detected pests – primarily insects – by 52%. Little is known about the presence of pathogens on wood packaging – according to some experts, inspectors rarely even look for pathogens. So I think the authors’ suggestion might not fully explain the continuing introduction of pathogens that attack tree species used in plantation forestry in New Zealand.

Prof. Michael Wingfield of South Africa has written numerous articles on the spread of pathogens that attack Eucalyptus on seeds imported to establish plantations in various countries; one such article is available here. This seems a more likely explanation to me.

The study’s analysis demonstrated that the overall rate of non-native fungal pathogen establishment in New Zealand was more strongly linked to changes in import trade volume than to changes in numbers of international passengers arriving on the islands. Although Sikes et al. don’t explicitly raise the question, they note that New Zealand has put considerable effort into screening incoming people – which appears from these data to have a smaller payoff than imposing phytosanitary controls on imports.

Recent declines in surveys mean the authors must estimate current pathogen arrival rates. The data gaps exacerbate the inevitable uncertainty associated with the time lag between when an introduction occurs and when it is detected. They estimate that an average of 5.9 new species of fungal pathogens per year have established on the focal host plant species since 2000. They estimate further that 55 species of pathogens are present in New Zealand but have not yet been detected there.

I am quite troubled by the reported decline in New Zealand’s postborder pathogen survey efforts since about 2000. This appears very unwise given that the risk of new introductions of pathogens that attack fruit and forestry trees continues – or even rises! Indeed, scientists associated with the forestry industry note the risk to Douglas-fir and Monterrey (Radiata) pine plantations from the pitch canker fungus Fusarium circinatum – which could be introduced on imported seeds, nursery stock, and even wood chips. Radiata pine makes up 92% of softwoods planted – and exotic softwoods constitute 97% of the plantation forestry industry.

Furthermore, non-native pathogens threaten New Zealand’s unique forest ecosystems. Since this study focused on non-native plant hosts, it does not address the risk to native forest species. However, the threat is real: Kauri trees – the dominant canopy species in some native forest types – is suffering from a dieback caused by an introduced Phythopthora. Also, two other pathogens threaten the many trees and shrubs in the Myrtaceae family found in New Zealand – Puccinia rust (which is established in Australia but not New Zealand) or the Ceratocystis fungi causing rapid ohia death – both threaten native forests in Hawai`i, as discussed in a recent blog.

Posted by Faith Campbell

The United States is Being Left in the Dust on Amphibian Disease Prevention

For a short time, the U.S. was the world leader in regulating to prevent introduction of a foreign amphibian disease that has caused a deadly epidemic in Northern Europe – and could cause the same outbreaks here. Unfortunately, we have since surrendered our leadership. But, we still can and must act. Here is the story as I have seen it unfold (having begun my advocacy on this particular threat in late 2014).

The fungus Batrachochytrium salamandrivorans (“Bsal”) is carried on the skin of a large number of salamander species; it was first described in 2014. To help prevent Bsal from arriving and killing native salamanders, the U.S. Fish and Wildlife Service (FWS) published its “Interim Rule” in January of 2016 to list 201 salamander species as “injurious wildlife” under the Lacey Act (available here; the list of blocked species is here). The FWS had determined that Bsal caused major die-offs of salamanders in Europe and posed an imminent threat to our U.S. native populations. The fungus, which had very likely been carried from Asia to Europe via the pet trade, is not known to exist in the U.S., which is a very fortunate thing because we are the global “hotspot” for salamander diversity. An array of beautiful and popular species are found across the nation, especially in the Appalachian and south-eastern States and the Pacific Coast States.

That 2016 regulation was an important advance fought for by many amphibian conservation advocates and experts. We were proud that ours was the first government to take proactive steps. Unfortunately, the FWS regulation’s focus on just 201 salamander species — out of more than 650 named species worldwide — meant that the regulation was not protective enough to reliably keep Bsal out (as scientists had stressed to the FWS back in 2015). However, we took hope from the fact that it was an “Interim” regulation responding to the urgency of this new risk and the agency had repeatedly announced it intended to revise it into a Final Rule, which process could toughen it up. However, two and a half years have gone by with no action.

In the fall of 2017 the new Bsal science was showing even greater risk than was understood before. This was gathered into a comprehensive Scientists’ Statement of Reasons for a Class-wide Moratorium of Amphibians in USA Import Trade to Prevent Entry of Bsal, signed by 12 leading amphibian health experts (available here). Further driving home the need for toughening the Interim Rule, in February of 2018 a crucial paper came out, the Yuan et al. salamander study, Widespread occurrence of an emerging fungal pathogen in heavily traded Chinese urodelan species. (Conserv Lett. 2018;e12436). Reviewing Table 1 therein reveals that of 8 species that tested positive for Bsal infection in China, when compared to the 201 species regulated under the FWS Interim Rule, at least 3 species were positive for the infection that are not prohibited from import: Andrius davidianus, Pachytriton wuguanfui and Paramesotriton aurantius.

To reiterate: the Interim Rule allows unregulated Bsal-infected species from China to be imported. Further, we know the list of native U.S. species regulated under the list of 201 species is underprotective. Knowledgeable scientists say that Bsal can infect and harm at least 5 additional native species beyond those the FWS listed, while many more unlisted species can act as carriers of the pathogen. (That research likely will be published over the course of this and next year.) In short, the 2016 Interim Rule now looks like Swiss cheese.

Meanwhile, we have given up our Bsal leadership position to Canada, the European Union and the United Kingdom. After first adopting a 1-year import moratorium, Canada now (effective May 12, 2018) prohibits imports of all species of the order Caudata (salamanders, newts and mudpuppies) except via a special permit (available here). Taking a different approach, at the end of February the European Union recommended a sweeping “Clean Trade” program relying on pre-shipment certifications, applicable to both imports into the EU and trade between member nations (available here). The EU animal health authorities recommended that members allow no commercial salamander shipments without risk mitigations, such as detailed quarantines and testing of shipments.

Just recently the United Kingdom followed the EU recommendation and adopted a strict health certificate and quarantine approach for salamander and newt imports targeted to prevent Bsal (available here). It involves three, alternative, detailed quarantine options, while allowing importers to propose a different quarantine approach if it is based on peer-reviewed published science.

To make matters look worse for the U.S. by comparison, this Administration has for no clear reason disengaged from the previously-announced FWS plan to finalize the underprotective Interim Rule. There was a public comment period that ended in March of 2016. Because of that now two-year old closed comment period, the FWS officials in charge just this past April flatly refused to meet with a group of salamander experts to discuss the implications of the new science mentioned above. Then, we found out that the FWS actually officially has delayed finalizing the Interim Bsal Rule indefinitely; the agency now classifies it as a “Long-term Action” with no planned date for completion. (Per White House, Office of Management and Budget, Unified Regulatory Agenda, here).

This administrative slow-down is remarkably unfortunate. Rather than reflecting the new realities and proposing a state-of-the-science “Clean Trade” approach like the EU and UK, or mandating a permit for all salamander imports like Canada, or at least adding the other known unlisted Bsal-carrying and Bsal-vulnerable species to the list of 201 prohibited species adopted back in 2016, the FWS now appears content to expose the country to the risk of this devastating wildlife epidemic via unregulated imports.

It would be one thing if there was some overwhelming economic value to salamander imports, but that is not so. Salamander imports make up a tiny part of the pet trade – their total dollar value is paltry compared to other imported animals. Neither the organized pet industry nor anyone else is actively trying to block progressive protections. Indeed, the pet industry will itself benefit greatly from not having Bsal here infecting its own commercial pet supply. And the industry will benefit from not being blamed if or when released pet salamanders spread Bsal into the wild, which is an all-too-likely scenario based on past species and pathogen incursions.

As called for in the 2017 Scientists’ Statement mentioned above, in order to protect our priceless North American salamander fauna we need a “class-wide ban” – at least. This can and should still allow for appropriate exceptions under FWS permits for education, research, display and other important uses as are already provided for under the Lacey Act.

If you would like to get involved in the informal “Bsal Discussion Group” that is engaged in advocacy to improve the FWS regulation, please contact me at: jenkinsbiopolicy@gmail.com.

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PART II, coming soon, will delve into the new science about the “old” emerging amphibian epidemic, Bd, which has devastated frogs and toads across the planet.

Posted by Peter Jenkins