Saving endangered species with herbicides

ResearchBlogging.orgThe latest issue of Cicindela (a quarterly journal devoted to tiger beetles), which arrived in my mailbox last week, features an article coauthored by my good friends Kent Fothergill and Kelly Tindall of Portageville, Missouri, along with lead author Stephen Bouffard of Boise, Idaho (Bouffard et al. 2009).  The article reports the results of a vegetative management pilot test for using herbicides to restore habitat for the critically imperiled St. Anthony dune tiger beetle, Cicindela arenicola.  This species is endemic to Idaho, primarily the St. Anthony Dunes area in the southwestern part of the state (Pearson et al. 2006), and like the Coral Pink Sand Dunes tiger beetle (Cicindela albissima, recently covered in this post) it is restricted to sand dune habitats that are threatened by a variety of land-use practices, including motorized vehicle use, livestock trampling, intentional stabilization of dunes by grass seeding, conversion of dune habitats to agriculture, and disposal of public lands by transfer to private ownership (Idaho State Conservation Effort 1996).


Cicindela arenicola, copyright © Kent Fothergill 2008

Bouffard et al. conducted their study at Minidoka National Wildlife Refuge in southern Idaho. Cicindela arenicola was recorded on small remnant sand dunes within the refuge during the mid-1990’s but had not been detected in more recent opportunistic searches. The authors noted that the sand dunes appeared to have become overgrown with the invasive annual grass, downy brome (Bromus tectorum). Their study comprised three elements: 1) herbicide treatment on dune habitats to reduce downy brome density; 2) surveys of treated versus untreated plots during the following season to assess the efficacy of the herbicide in reducing downy brome density and any effect it might have on native vegetation, as well as the presence of C. arenicola; and 3) laboratory bioassays to evaluate the acute toxicity of herbicides on a surrogate tiger beetle species, Cicindela repanda (common shore tiger beetle). The laboratory bioassays were necessary, because toxic effects by a herbicide against tiger beetles would negate its potential usefulness for habitat improvement. For the herbicide treatment plots, Imazapic (trade name Plateau®) was selected because of its effectiveness against downy brome, minimal effects on native vegetation, and low toxicity to animals, including insects. Imazapic is labeled for control of downy brome and for use on rangeland. A nonselective herbicide, glyphosate (trade name Touchdown®) was also evaluated in the laboratory bioassay, even though it was not used in the field test, because glyphosate-based herbicides also have low animal toxicity and have been shown to be effective in assisting the establishment of native plant species in prairie restorations.

The authors were successful in observing live adult C. arenicola in both of the test plots where adults of this species were last seen in the mid-1990s. Moreover, larval burrows – putatively representing this species – were also noted in the plots. No adults or larvae were seen in a third plot; however, no previous records of the species exist in the area where that plot was located. They noted the presence of residual downy brome stems from the previous season’s treatment in the sprayed plots but no new growth, while the untreated controls exhibited extensive new downy brome growth. More importantly, no negative impacts on native vegetation – principally rabbitbrush (Chrysothamnus sp.) and Indian ricegrass (Achnatherum hymenoides) – were noted in the sprayed plots. The third plot had only a light downy brome invasion prior to treatment, and no apparent negative effects were observed on the native bunchgrasses, rabbitbrush, and sagebrush (Artemisia tridentata) in this plot after treatment. In the laboratory, neither imazapic nor glyphosate showed evidence of acute toxicity against the surrogate tiger beetle, C. repanda.

While the use of herbicides for conserving endangered species may seem counterintuitive, this study demonstrates a potential use for herbicides in restoring and improving sand dune habitat for a critically imperiled species of tiger beetle. Herbicides that are effective in reducing invasive annual grasses with minimal effects on both native vegetation and tiger beetles could greatly facilitate habitat management for a number of critically imperiled western U.S. sand dune tiger beetles besides C. arenicola, including C. albissima in southwestern Utah, C. waynei (Bruneau tiger beetle) in western Idaho, and C. theatina (Colorado Great Sand Dunes tiger beetle) in southern Colorado. Where vegetational encroachment presents a threat to critical sand dune habitat, broad spectrum or grass selective herbicides may offer an effective and convenient alternative to habitat restoration. Additional research will be needed to determine if repeat applications of herbicides will be necessary to prevent reinvasion, and if so with what frequency, as well as the chronic or behavioral effects of herbicides on both larval and adult forms of the insects targeted for conservation.

I thank Kent Fothergill for allowing me to use his beautiful field photograph of C. arenicola, which also graces the cover of the current issue of Cicindela.


Bouffard, S. H., K. V. Tindall and K. Fothergill. 2009. Herbicide treatment to restore St. Anthony tiger beetle habitat: a pilot study. Cicindela 41(1):13-24.

Idaho State Conservation Effort.  1996.  Habitat conservation assessment and conservation strategy for the Idaho Dunes Tiger Beetle.  Report No. 7, Boise, ID.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

Copyright © Ted C. MacRae 2009

Add to FacebookAdd to NewsvineAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to Ma.gnoliaAdd to TechnoratiAdd to Furl

25 thoughts on “Saving endangered species with herbicides

  1. Hi Ted

    I am not sure if I agree 100% with the conclusions of their study. You might want to check out a recent paper by Cheryl Russell and Cheryl Schultz titled “Effects of grass-specific herbicides on butterflies: an experimental investigation to advance conservation efforts” that was published in the recent issue of Insect Conservation. Briefly, the survival of Pieris rapae was reduced by 32% with sethoxydim and 21% with fluzifop-p-butyl; Icaricia icarioides blackmorei experienced a 21% reduction in development time from the date of treatment to eclosure. The larvae are susceptible through ingestion, but also through dermal exposure from direct contact (benig sprayed) or contact on the plants/ground when they are crawling. Obviously caterpillars eat plants and tiger beetles eat bugs, but it’s my understanding that not only are the herbicides a possible concern, but the surfactants also may be an insecticide. I am told the U.S. Fish and Wildlife Service is looking into the effects of some herbicides on the larvae of the endangered Lange’s metalmakr butterfly. I am not sure if these studies have been completed.

    My point is NOT to stop the use of herbicides to restore and enhanced habitats for endangered and rare insects, but to point out that land managers should be aware of the possible effects of these chemical agents. Invasive exotic plants are a major concern to just about every preserve, park, refuge, etc I know of, and proper use of herbicides are an important tool in conserving the native plants and anmals.

    • Hi Truman. Certainly you are correct in urging caution until the full potential effects of herbicides are known. The authors point this out, as do I at the end of the post.

      There is not much information yet about the effects of imazapic on insects, but glyphosate has been thoroughly tested for many years due to its widespread utilization in vegetative restoration projects. Laboratory bioassays have for the most part found no toxic effects, although surfactants and formulation ingredients have on occasion been found to have some effects. In a few cases glyphosate has shown some toxic effect on selected insect species. However, it must be remembered that laboratory bioassays often utilize doses many times above field use rates, and, moreover, that “risk” is not a function of toxicity alone but rather a combination of toxicity and exposure. Even low to moderately toxic substances can present great risk if there is high exposure, while conversely highly toxic substances can present little or no risk if there is little or no opportunity for exposure. Insect activities are often highly temporal, providing an opportunity to time herbicide applications during periods when insects are not active and, thus, minimize exposure risk.

      Of course, the proof is in the pudding, and the fact that the tiger beetle was once again detected after herbicide applications where it had not been seen for many years is promising. Again, both the authors and I stressed that herbicides may have potential utility in habitat restoration programs and that additional research is needed to understand how best to utilize this potential tool.

      Lastly, one cannot talk about habitat management tools currently at our disposal without mentioning fire – which more than any other tool has extreme detrimental acute effects on insects 😉 Again, timing is critical to avoid unsustainable adverse impacts. Obviously, the utility of any habitat management tool must be judged by population-scale impacts and not just effects on individual insects.

  2. What I find interesting here is the effect of fire. In the previous article on the oaks, fire is necessary for the propagation if the seed, yet in this article, a danger to the insects. Seems like no middle road on this one.

    In Kruger they burn the grass every year and though this stimulates beautiful growth of it for the animals too eat, maybe it is very detrimental to the insect population. I wonder if any studies have been done on this?

    Is it also not better to use target specific herbicides? I do agree that this would be a great way of controlling invasive plant species.

    On the other hand, I have to wonder how much good or harm us humans do with “invasive” species. Truman raises a good point. Here Lantana is sprayed all over the country in order to get rid of it, yet it is a great source of food for many butterflies. Without the Lantana, would there not be fewer butterflies?

    I go round and round the circle of “do humans interfere too much in nature”. Hasn’t nature survived for millions of years without our “help”?

    Maybe being a layman, I do not see things in situations which scientists do? 🙂 Lantana DOES take over in some places, but I would not want to eradicate it altogether.

    • Hi Joan. I’m afraid I was being a little tongue-in-cheek with the reference to fire. My point was that even though fire is 100% fatal to an individual insect, insect populations that thrive in fire-mediated natural communities rely upon periodic burns for their survival. The fire does kill whatever insects are active at the time of the burn, but the population either is not impacted because the insects were in a protected dormancy at the time of the fire, or it recolonizes the burned area from adjacent unburned habitats. It’s a short-term hit but a long-term benefit. The same goes with herbicide treatment or any other disturbance factor (e.g., mowing, grazing, mechanical removal, etc.) that can be used for habitat management – there may be short term negative impacts on certain insects, but the maintenance of a quality habitat allows for long term viability of the associated insect fauna.

      When using fire, herbicides, or any other management tool for habitat improvement, timing is the key. For example, in our Midwestern prairies, fall burns are generally less detrimental to insects than spring burns because the majority of prairie specialist species are active during the spring. Fall fires are also more effective because of the higher amount of fuel present from senescing plants, and they are easier to manage in terms of preventing escape into adjacent woodlands because the fully foliated forest canopy creates higher humidity conditions that inhibit fire invasion. Same thing with herbicides – if applications are timed to periods when critical insect species are not active, much of the risk of exposure can be avoided.

      As far as your introduced Lantana, it does attract butterflies, but it does not provide a larval food source for them. It merely concentrates from the wild the existing butterfly populations. Unfortunately, its invasive nature means that it is displacing native plants – plants upon which innumerable native insect species rely upon for food. In areas where Lantana has taken over, those insects now find themselves without a host plant – perhaps including some of the butterflies that nectar at the Lantana. Invasive exotics are never good for the local ecosystem.

      Yes, nature has survived for many years without us, and she will survive long after we are gone. While we are here, however, we have a responsibility to preserve as much as possible to the best of our ability and to repair what we have spoiled. It is an act of generosity – in an age where we have the capacity to impact every single square inch of this planet – to show willfull restraint on our domination, to pledge to future generations that we will not rob them of the chance to see the wonders that we still have the chance to see. Perhaps I am waxing way philosphic here, but I think it is better to try to put things right and make mistakes from which we learn than to do nothing out of fear of making a mistake. The study I talked about in this post did just that – and their results give us hope that, at least for this tiger beetle in this habitat, we can indeed do something about it.

  3. A good explination of the fire Ted. Thanks. As I said, I did not know some of the other facts concerning burning.

    The info on the Lantana and the butterfly larvae also makes more sense now. You are always a wonderful fountain of information. Thank you.

    I do agree that there are some institutes and bodies which are trying very hard to put things right which we destroyed and damaged in previous times and I applaud them. They are doing a marvelous job at setting aside natural reseves and to stop things like people riding on the sand dunes of the beaches.

  4. These last 2 posts were very informative and touch on some of the management that occurs with one of the listed species, the red-cockaded woodpecker, that I work with. In areas where longleaf pine historically occurred, fire suppression has let hardwood, including oaks, tulip, sweetgum, etc… to grow where they wouldn’t normally occur. A 1-3 year fire cycle would have historically kept these species in check in areas of longleaf pine; moslty upland sites.

    In areas where hardwoods have taken over and are too big in diameter to fell with a hydroax we have to take them out with loggers. Once this is done a “hack and squirt” method is usually used to insure the stumps don’t resprout. Of course, in these areas the return to a regular fire regime is ultimately what keeps them in check. Red-cockaded woodpeckers will abandon their cavity trees, which are in living pine, and forage areas if the midstory or canopy become choked with hardwood. They prefer the open park like settings that occurred prior to European settlement and the onslaught of fire suppression that followed.

    • Hi cedrorum – thanks, and nice to hear from you!

      Excellent comments illustrating what happens to “wilderness” when we leave it alone. There is little true wilderness left because we have already fragmented the landscape, suppressed the fires, and extirpated the megafauna that helped shape the original landscape. The habitats don’t sustain themselves without management, because we have interrupted the natural processes that created them to begin with.

      My understanding is that “hack and squirt” is also useful for thinning undesireable understory (e.g., maples in oak woodland) before canopy replacement takes place and where burning isn’t feasible – e.g., on private holdings with owners who are concerned about the “visual disturbance” caused by mechanical removal or burning. This makes them more willing to embrace management of their lands rather than allowing stand replacement to continue.

  5. Hi Everyone!

    Fascinating posts!

    Many years ago, while working on field studies of the endangered species Dr. Rudi Mattoni told me that in California, all ecosystems and habitats now require managment by humans. He had made the astute observation that the loss of Pleistocene megafauna, dramatic reduction in the size of most habitats, and the overwhelming invasion by exotic plants and animals (among other anthropogentic impacts) has resulted in the loss of natural cycles. Rudi noted that we now manage habitats for butterflies, kangaroo rats, grizzle bears, etc etc but the natural systems, flora and fauna, have been lost and so the hand of man is required to replace these natural factors. It is something that I have thought alot about over the years. I would say this the case in nearly all terrestrial ecosystems on Earth.

    Also, we have some nitrogen-poor habitats here, like serpentine grasslands and coastal dunes where burning is not a good idea because it puts nitrogen back into the system, when you want it out or reduced. So, things like controlled livestock grazing, herbicides, or pulling out or burying the weeds are used.


    • Hi Truman. I couldn’t agree more – your points not only illustrate the problems with managing habitats for single species, but also that no one tool is useful in all situations. We have to tailor our efforts on a case by case basis using the broadest diversity of management tools at our disposal.

  6. Everyone – thanks so much for this great conversation. I have some excellent ecologists among my readers and greatly appreciate your insight in these discussions.

    Returning once again to fire, I should point out that I fall a little bit on the cautious side of the current “burn, baby, burn” vs. “chill with the burning” debate for managing our present day prairie/glade relicts. I fully understand the benefit that prescribed burns offer in terms of reinvigorating herbaceous flora and checking woody encroachment and advocate greater use of fire in our remnant prairies and glades. However, in the presettlement landscape, fires happened with irregular frequency and varied from slow, cool burners to devastating conflagrations. The scale of the presettlement landscape tolerated this because it wasn’t fragmented, allowing recolonization from adjacent unburned areas. Many of our present day prairie and glade relicts – especially forest/prairie biome transition here in Missouri and Illinois, are extremely small “postage stamp”-sized parcels, usually surrounded by a vast sea of agricultural fields (prairied) or closed forest (glades) – inhospitable habitat for most prairie/glade specialist insect species. Prescribed burns that are conducted without considering the invertebrate fauna with regards to timing, frequency and scale can lead to local extirpation within that fauna since there is much reduced opportunity for recolonization from adjacent areas. This is particularly true for species with limited dispersal capabilities (such as some of the flightless tiger beetles that so enamor me!). The floral community may look beautiful, but it is ecologically depauperate if critical insect associates are missing, and long term some plants may not be able to sustain themselves (e.g., if critical pollinators are missing). Frequent burning may be appropriate in the initial stages of restoration projects, but fire must be used much more carefully when renovating existing, degraded relicts – especially those greatly isolated from similar habitat.

    I would dealy love to hear what Allison and James think about all of this!

  7. Burning can be real hazardous, politically. The USFS has done a great job telling us that fire is bad, but by doing so has cost them a valuable tool. If a prescribed fire is not contained and property is destroyed, someone will lose a job, career, and credibility. Which is why some land managers won’t allow prescribed burns. Political suicide. And most people just don’t get understand fire, and how it relates to an ecosystem. Done right the benefits abound (especially in the tick laden Northeast). Done wrong, your goose is cooked.

    You wrote a good piece,Ted. It’s good to see other resource control tools available.

    • Hi Kirk. Thanks, and you make a good point – the decades-long USFS “Smokey the Bear” campaign really did a number on the public’s perception of fire, and now ecosystems are paying the price.

      It is possible that herbicides as well will face an analogous, though different uphill battle. I fear that many lay people, green-leaning but not particularly aware of the intricacies of habitat restoration, will be shocked and incensed when they find out that “poisons” are being sprayed in protected wilderness. Opposition to herbicides as a management tool may, ironically, come from people who otherwise support conservation.

  8. Holy cow. Fire, wilderness, herbicide treatment for the good of the community, grazing as a management tool…where does a girl start? First, excellent post and I’m super proud of Kent and Kelley for their work. I still don’t understand how all of you manage to photograph things that move. Notice that all my non-plant pictures are taken in hand–from snakes to frogs. Also, you’re a fine ecologist, just what the entomology world needs.

    Okay: yes, non-target species should be surveyed as well when employing herbicide treatments. You’re right, that herbicides are integral to combating invasive species; I can’t tell you how many millions of gallons of Remedy are used in Missouri to deal with sericea. You’re right, again, that even though lantana is a good nectar source, it is not a plant native to the life histories of any native species and that the populations it attracts are artificial. I am reminded of a hare-brained process in the USFS wherein ranger districts are required to build pollinator gardens, when, really, if they wanted to positively affect their invertebrate populations, they should be restoring their ecosystems. Nevertheless, non-natives should be controlled in every situation. The annual burning of cheat grass out west has been utterly detrimental to the native flora. Kent could write a book about the disappearance of sagebrush steppe communities in light of cheat grass invasion. And you’re right about prescribed fire intensity and frequency: the key to implementation of prescribed fire is to best mimic the natural processes that gave rise to the community–most often a patchy mosaic burn at different times of the year. I turn again to HHT and their fire program, a very successful program that involves implementation at various times of the year, various humidities, a 3-5 year cycle. I still think the annual Flint Hills fires are detrimental to biodiversity. The goal of their annual burning is to create more forage for livestock; if it was biodiversity, they wouldn’t’ be burning every year in mid April when humidities are so low that the fires race across the prairie in record speed, leaving nothing in it’s wake but a blackened landscape.

    Finally, in light of exotics, fragmentation, and the interruption of natural processes, even wilderness requires active management. Check out the toolboxes on and see that thinning, fire, exotic species control all play an integral role in maintaining the naturalness of our precious wild landscapes.

    Thanks, Ted, for sharing your brilliance with the world. You’re lucky to have such thoughtful readers. (By the way, have you ever received a comment from a strange eco-terrorist group in India? I did last week and quickly deleted it from my inbox…)

    • Hi Allison. Thanks so much for chiming in and sharing with us your sage perspective. Your comments further support much of what has been discussed here – if this post does anything at all, I hope it helps people become more aware how truly great the challenges are with habitat restoration and the many, often conflicting priorities that must be considered. We need the fullest arsenal of tools at our disposal if we are to meet these challenges.

      I am especially concerned about the annual burning in the Flint Hills of Kansas. The FH are the last stronghold for the swift tiger beetle (Cicindela celeripes) – I wrote about this particularly vulnerable and flightless tiger beetle species in my post, The hunt for Cicindela celeripes. Perhaps the beetle’s limited adult activity period in late June and early July is the only thing that protecting it from these far too frequent burns.

      Eco-terrorists? Oh, lord! Don’t we all want the same thing?

  9. What a great post and discussion. I use both fire and herbicides in managing the prairie remnant near Chicago that I’m co-steward of. I think it’s very important to try to keep as much of the entire ecosystem in mind when crafting management plans. Some organisms seem to have contradictory requirements, particularly regarding tools like fire. Too many folks want to manage for just the plants, or the birds, or the butterflies. I wholeheartedly agree with your observation that no one tool is applicable in all situations.

    • Hi Doug – I figured I might have your support in this discussion, since your perspective is among those that have guided my thinking about this subject over the past year or so.

  10. Thanks, Ted — This is a good and necessary discussion, the end of which, figuratively, is far off in the future!

    In our zeal to restore composition and structure, and frankly beauty, to the native plant communities in our care, it is perhaps true that those of us who use fire as a management tool have not been sufficiently cautious with it. This maybe especially true on small remnants, but the annual, large-scale, late burns in the Flint Hills may be no less damaging. Thank goodness for the long interval burn plots at Konza LTER, I think. Unfortunately, we really don’t know what the impacts of of it all are. It would be good to have more substantial knowledge about the issues impacting insect diversity.

    It would be desirable to have a body of good and abundant data, and carefully considered conclusions from them, on what it really is that matters for the health of conservative organisms’ populations. Careful study could reveal that conservative insect declines result from inadequate chilling in recent shorter winters, change in arrival times and population levels of key predators or parasites, pesticide drift, exotic pathogens or parasitoids or competitors, lack of a grazing component in vegetation management, or other things, or any combination of these, with or without unwise fire policies. I feel that I, at least, genuinely do not know why we’re seeing the trends of decline in ecologically conservative insects.

    Caution seems appropriate, but I am often at a loss to feel I authoritatively can state in what way such caution should be exercized.

    • Hi James. I was hoping you would chime into this discussion with your unique blend of entomological expertise and habitat restoration experience. Of course, you nail the central issue, and that is we just don’t have much more than intuition and suppostion to go on, and even more importantly, that there are a whole host of other potential causitive factors in the observed declines that can be unrelated to any particular management technique. It is unfortunate that so few relatively unaltered parcels remain that would allow the collection of a good body of data – it seems we are stuck with our intuitions. In the end, if we can get people to at least consider the invertebrate fauna when making decisions, that alone may be an improvement.

  11. I have to add this, also posted in early the same form at the Iowa Insects list serve:

    I heard a talk yesterday on experimental prairie restoration recently by Bryan Foster of the University of Kansas (and chatted with him afterward), in which he showed a slide comparing per meter squared herbaceous plant diversity of grasslands around the world. The slide and subsequent discussion indicate:

    –Tallgrass sites have a range of 15-30 species per m2, with higher means in annually hayed prairies compared to annually burned sites.

    — Numbers tend just a bit higher in sandy oak savanna in Minnesota.

    — Never-burned but annually hayed meadows in northern Europe (Estonia) have 50-60 species per m2, with some to the south (Czech Republic) having as many as 80-90.

    — Shrub savannas in subtropical eastern Australia have over 200 genera of herbaceous plants per m2, these perhaps not actively managed, but coursed only occasionally (once a decade or longer) by ferocious wildfires, such as this year.

    Further tangential thoughts and memories:

    — Several ecologists and native plant seed collectors here in Missouri have commented to me informally that the most diverse and flowery prairies among those they frequent in here are those that were annually hayed for a long time before they were protected.

    — I also hear that many of Europe’s rarest and most ecologically specialized insects are found in northern Europe only in hay meadows, but also may be holding their own in the rather poorly studied, grazed montane grasslands in the Pyrenees, Apennines, Alps, etc.

    Admitting that these numbers may not be strictly comparable inter se, they suggest that maybe burning isn’t even that good for plant diversity. Food for thought at least…

    As one who manages with fire, you can see, I don’t do so without internal conflict…

    • Hi James. That was really interesting, and it really doesn’t surprise me. Removal of the grazing component from prairie systems seems to get far less attention than lack of fire, yet one must think that grazers had at least as significant a role in the ecology of those systems, maybe more considering grazing happened regularly and uniformly across much of the prairie landscape. This can’t be said about fire.

      I know that the tiger beetles I study in the prairies are found with much greater frequency along paths and wallows created by cattle or bison. They rely upon disturbance factors to create sparsely vegetated, open ground – fire doesn’t do that. I find far fewer tigers in prairies that are not grazed (except along roadsides, where disturbance by man creates open ground), and I don’t think I’ve ever found a tiger in an area managed by frequent burning. I know this is only my own experience and not the result of rigorous study, and also that the invertebrate prairie component consists of more than just tigers, but seeing this over and over just makes me wonder.

  12. Pingback: Circus of the Spineless #39 « Bug Girl’s Blog

  13. Pingback: St. Anthony Dune Tiger Beetle « Beetles In The Bush


Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s