[APWG] Ecosystem Restoration and Biological control of invasive species by import of alien species Fw: NEWS: Invasive Saltcedar Triggers Lively Debate

[Wayne Tyson]

APWG: 

I have [[inserted thus WT]] my comments in response to Dr Lair below. I appreciate his sentiments and generosity in sharing information. I hope the APWG community can pursue this discussion objectively and effectively. I, for one, am not arguing "against" the beetle, and certainly not "for" ignoring Tamarix infestations. For something as frustratingly widespread as Tamarix, it is little wonder that there is a heartfelt desire for a "silver bullet." I certainly hope the bug is the solution, but I still would like to see more than generalized promises from the experts. 

Despite a history of failures (doing the same thing over and over and expecting a different result), I believe the primary reason lies in inadequate methodology, not "competitiveness" when it comes to restoring infested sites to indigenous species. Tamarix always will be with us, but it doesn't have to be accepted as a dominant species in areas where indigenous species have the right conditions to thrive. Consider the fact that, while Tamarix is a tough species well-adapted to certain kinds of extreme environments, many indigenous species also are tough species adapted to the same environments. 

A little paradigm shift might be useful. 

I refer all to my original post. 

WT

----- Original Message ----- 

From: Ken Lair 

To: landrest at cox.net 

Sent: Tuesday, August 25, 2009 9:58 AM

Subject: RE: [APWG] NEWS: Invasive Saltcedar Triggers Lively Debate

 

Mr. Tyson,

 

As a former member of the scientific team (comprised of ARS, APHIS, USBR, USFWS, as well as several universities and state agencies) that has been dealing with the release of the saltcedar leaf beetle (Diorhabda spp.) since the 80's, I would like to briefly address your concerns noted below, including some references to scientists and their published literature that perhaps you have not pursued.  I can appreciate your concern over the release of a non-native control agent, as it echoes the thoughts of many.  However, a few things should be brought to light (again, briefly here, with follow-up left to you).

 

By far, the Diorhabda leaf beetle has been the most researched and evaluated biocontrol agent, for host-specificity and native plant and crop safety under quarantine and controlled conditions, of any insect ever brought into this country for the control of an invasive plant.  It has been thus studied since 1986.  

 

[[While I do not disbelieve this generalization, I have no way of knowing what "most" means in terms of the issues I raised.  WT]]

 

I would refer you to the following scientists (a selection among many), who can provide you with ample literature and experience developed with this beetle and its release since 1986:

 

[[Thank you. However, please understand that my concerns are based on the generalizations of the "press-release" as apparently the only vehicle which the organizations and individuals involved think is necessary for communication to the public and interested individuals and groups outside those organizations. I gave examples of areas of knowledge which, according to my understanding, should be considered in such investigations; my purpose in posting my remarks was to elicit comments on their validity and to determine whether or not, if valid, they had been performed in the 23 years of extensive research. WT]]

 

Dr. Jack DeLoach

Agricultural Research Service

Temple, TX

http://www.ars.usda.gov/pandp/people/people.htm?personid=1336

 

Dr. Ray Carruthers 

Agricultural Research Service

Albany, CA

http://www.ars.usda.gov/pandp/people/people.htm?personid=894

 

 

Dr. Tom Dudley,

Riparian Invasive Research Laboratory - Marine Science Institute

University of California - Santa Barbara

Santa Barbara, CA

http://rivrlab.msi.ucsb.edu/lab_webpage_019.htm

 

Dr. Dan Bean, Director

Palisade State Insectary

Colorado Department of Agriculture

Grand Junction, CO

http://www.colorado.gov/cs/Satellite/Agriculture-Main/CDAG/1167928159775

 

The closest relative to the Tamarix genus in North America is Frankenia, to which the beetle has shown essentially no preference for herbivory in controlled choice tests under quarantine and in controlled field trials.  Without Tamarix as a food source (which is unlikely, given its abundance and distribution throughout western riparian systems), the beetle populations die.

 

[[Do I presume correctly that Frankenia was the only species other than Tamarix spp. "tested?" Was the assumption made that Diorhabda spp. could only "shift" from Tamarix spp. to Frankenia spp. and no others? Was taxonomic proximity the sole consideration? How long did tests run (longest and shortest period)? WT]]

 

The herbivory behavior of the beetle is as close to a "scientific certainty" as can be achieved in this discipline, even in regard to possible future "evolution" to a different "prey base".  

 

[[When one implies that terminology might be inappropriate, it is appropriate and expected that alternative terms are suggested. Ok, if the above statement is correct, what is the basis for the certitude? Something a bit more detailed, but short of referring enquiries to volumes of research that can't be read and evaluated for years would seem to be within the ability and mission of qualified experts. Did the research include, and find, that this organism is incapable of evolving or shifting into a population that can survive on another substrate/food source? Is it known to a scientific certainty that organisms (including beetles), once having evolved a species-specific relationship with a single plant species will become extinct once that plant species is no longer available? To what degree, in the natural habitat of this beetle, does it achieve "control" of Tamarix spp.? What level of control of Tamarix spp. is expected once the Diorhabda spp. populations are established? Is more than one species of this beetle being introduced? Why? WT]]

 

One can postulate that there may be less "scientific certainty" that bees or wasps (or perhaps even genetically less dynamic animals such as dogs) may, at some distant evolutionary point, evolve into predators that prefer humans as a prey base.  The argument and the rationale are essentially the same - there are no "guarantees", but there are acceptable levels of scientific certainty, within which the beetle currently falls.

 

[[I suppose that's true of straw-men too. How, briefly, are "acceptable levels" determined? WT]]

 

More relevant questions, which many agencies are currently studying vigorously, include:

 

·       Can native riparian plant communities that have been displaced by saltcedar over time be re-established (sufficient for site stability, habitat values, and water conservation) at the same rate at which saltcedar may be controlled, either by the biocontrol agent Diorhabda or by any other means (e.g., mechanically and/or herbicidally)?  This is particularly an issue on arid, saline, upper-terrace floodplain sites in the desert SW that exhibit poor hydrology and are not amenable to re-establishment of more mesic cottonwood and willow communities.  This is my area of specialization. 

 

[[What about ecologically? While I do know of cases where in-planting of indigenous overstory has failed, the failures (of which I am aware) were more due to failure to properly reintroduce the appropriate indigenous species rather than their being, for example, "outcompeted" by Tamarix, a commonly-used fairy-tale of an excuse. WT]]

 

·       Are athel trees (Tamarix aphylla - the relatively non-invasive tree form of saltcedar that is commonly used for shade trees in desert SW developments - schools, recreational areas, homes) safe from the insect?  Again, the research under quarantine and controlled conditions over many years has demonstrated that it is considered safe from herbivory if any of the various species of the shrub form of saltcedar is present in the region (which is typically the case). 

 

[[What is it about Tamarix aphylla that makes it resistant to Diorhabda spp.?]]

 

I also cringe at the thought or suggestion, promulgated by some of the University of Arizona school of thought, that because saltcedar is so plentiful, we should consider it as a "naturalized" plant with benign attributes, much like Kentucky bluegrass or bermudagrass.  With aggressive invasives (such as saltcedar), this was the liaise fare attitude taken by many people, land managers and lay public alike, years ago toward knapweeds, leafy spurge, cheatgrass, yellow starthistle, kudzu, and many other invasives.  As a result, we now have hundreds of millions of acres dominated by these invasives, at the expense of native habitat and other ecological values.  It's too bad that as humans, we haven't "evolved" past this attitude to fully understand the dire threat these invasives pose because of their "seediness" and related invasive attributes. 

 

[[My comments are not rooted in this school of thought. It is clear that saltcedar has effective means for spreading to substrates to which it is ideally adapted-mile after riparian mile and other less-likely locations where its seeds can find the right conditions. It is less clear why there are superficially similar-appearing conditions which are not dominated by Tamarix spp. If Dr Liar is working on less-than-ideal Tamarix sites, comprehensive studies of the ecotones at the edges of those sites must have been done, yielding useful data. WT]]

 

Again, I understand and appreciate the concern about introduced biocontrol agents, and we should devote energy to providing maximum assurance that they are safe and effective.  Releases of the insect should be well-reasoned and designed in relation to site characteristics and the ability of a site to recover (naturally or assisted) to native conditions.  In my opinion, the saltcedar leaf beetle qualifies in this regard.  I would be glad to address further questions you may have, but the true experts for the insect release are listed above. 

 

[[I think we should shake this out at this level before bugging the experts. I am not unalterably opposed to the introduction of "pure" populations of predator organisms, even if all they will do is retard Tamarix stands and minimize their advance. But if alternative means (restoring healthy ecosystems) will get the job done to a similar extent with less risk, so much the better. Again, I think the researchers should do a better job of informing and justifying beyond authoritative generalizations. WT]]

 


Kenneth D. Lair, Ph.D. 
Associate Restoration Ecologist / Restoration Ecology Division Head
H. T. Harvey & Associates | Ecological Consultants 

7815 N. Palm Avenue Suite 310 | Fresno, CA 93711 
Main  559.476.3160
Direct  559.476.3162
Fax  559.476.3170

Cell  559.930.8595
klair at harveyecology.com 
www.harveyecology.com

 

 

 

 

 

-----Original Message-----
From: Jeff Davis 
Sent: Tuesday, August 25, 2009 8:29 AM
To: Ken Lair
Subject: Re: [APWG] NEWS: Invasive Saltcedar Triggers Lively Debate

 

 

----- Original Message ----- 

From: "Wayne Tyson" <landrest at cox.net>

To: <apwg at lists.plantconservation.org>

Sent: Monday, August 24, 2009 10:41 PM

Subject: Biological control of invasive species by import of alien species 

Re: [APWG] NEWS: Invasive Saltcedar Triggers Lively Debate

 

 

> APWG:

> 

> Much as I would like to see the truly invasive "saltcedars" sent back 

> where they came from, we're probably stuck with them--they're just too 

> seedy.

> 

> Much as I would like to see a savior, even in the form of a bug, the 

> true-believers ("Now land managers are adding new biological control 

> agents to their arsenal by releasing saltcedar leaf beetles (Diorhabda 

> elongata) imported from China and Greece. The small insects strip 

> saltcedar of its leaves, while ignoring native vegetation." 

> http://www.wssa.net/WSSA/PressRoom/WSSA_SaltCedar.htm ) in insect-messiahs 

> are at it again. These little buggers may "ignore" native vegetation for a 

> while, have they been DEMONSTRATED in a peer-reviewed manner with 

> replicated experiments to have left every species indigenous to the 

> Western Hemisphere to continue to do so? I await the evidence, and I 

> should not be expected to chase it down from a press-release.

> 

> A more serious question remains to be answered--do we know, to a 

> "scientific certainty," that such imported populations cannot and will not 

> evolve to survive on other prey?

> 

> WT

> 

> 

> ----- Original Message ----- 

> From: "Olivia Kwong" <plant at plantconservation.org>

> To: <apwg at lists.plantconservation.org>

> Sent: Monday, August 24, 2009 7:27 AM

> Subject: [APWG] NEWS: Invasive Saltcedar Triggers Lively Debate

> 

> 

>> http://www.wssa.net/WSSA/PressRoom/WSSA_SaltCedar.htm

>> 

>> Invasive Saltcedar Triggers Lively Debats Among Weed Scientists and Land

>> Managers

>> 

>> Saltcedar (Tamarix spp.) is an invasive plant that is crowding out native

>> vegetation and dominating the shorelines of southwestern rivers and

>> streams. But put a room full of weed scientists and land managers 

>> together

>> to discuss how to tame the aggressive plant and you'll trigger a lively

>> debate about how -- or even whether -- it should be controlled.

>> 

>> See the link above for the full text of the press release.

>> 

>> 

>> 

>> 

>> _______________________________________________

>> PCA's Alien Plant Working Group mailing list

>> APWG at lists.plantconservation.org

>> http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconservation.org
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