St. Anthony Dune Tiger Beetle

Sand dune habitat for Cicindela arenicola | vic. Idaho Falls, Idaho

After kicking off the 2011 fall tiger beetle trip by finding Cicindela formosa gibsoni and C. scutellaris yampae in the Yampa Valley sand dunes in northwestern Colorado, I was even more optimistic about my chances of seeing the main goals of the trip—the four C. maritima species group endemics that inhabit sand dunes in Idaho (St. Anthony Dune Tiger Beetle—C. arenicola, and Bruneau Dune Tiger Beetle—C. waynei), Utah (Coral Pink Sand Dune Tiger Beetle—C. albissima), and Colorado (Colorado Dune Tiger Beetle—C. theatina).  Each of these closely related species is restricted to a single sand dune system in their respective states, resulting in small populations that are especially vulnerable to drought and threats to their required habitats (primarily invasive plants and offroad recreational vehicles).  Cicindela arenicola, described from the St. Anthony Dune system of southeastern Idaho (Rumpp 1967) was our first target, and while the drive through the Snake River Valley—aspen and maple in blazing full color—was stunningly beautiful, all I could think about during the 6-hour drive was the rising temperatures outside and the tendency of these sand dune tiger beetles to dig in if it gets too hot.  I had information about several localities along the St. Anthony Dune system, and by the time we arrived at the first of these it was already early afternoon.

Cicindela arenicola adult burrows

Walking onto the dunes at a locality near Idaho Falls, it didn’t take long to find the unmistakable signature of adult activity—burrows.  Many insects (especially bees) and even non-insects (spiders, solifugids, etc.) that live on sand dunes create burrows that can look similar to those created by adult tiger beetles.  However, after years of experience I can almost tell at a glance whether a burrow has been created by a tiger beetle versus some other arthropod by the size and shape of the opening and appearance of the diggings.  When there is doubt, a little bit of excavating with a knife gives further clues in the shape of the tunnel—flatter than most other diggers and angling almost horizontally back into the sand before taking a dive a few inches back.  Wind quickly obliterates evidence of the burrow entrance and pile of diggings, so when these are present and fresh-looking the beetles have either just dug in or just dug out.  I excavated a number of burrows that turned out to be empty, suggesting the beetles were out and about if only I could find them.  And find them I did, mostly along the sloping, south-facing dune face above the flatter sand plain below.  They were as beautiful as I imagined they would be—bold, white markings, screaming green and copper highlights on the head and pronotum, and a dense covering of white hairs on the sides and undersurface.  They were also extremely active and wary, so much so that I didn’t even attempt to photograph them for the time being despite the decent number of individuals that we saw at the site.

Cicindela arenicola adult excavating burrow (click for better view of beetle just inside burrow entrance)

Cicindela arenicola in completed adult burrow | September 2011 | Idaho Falls, Idaho

There were other nearby sites that I had planned to check also, but with good numbers seen already and several other interesting insects (e.g., Crossidius spp.) found in abundance on the blooms of snakeweed plants growing on the backside of the dunes, there was really no reason to go anywhere else.  Besides, I still had not even attempted a field photograph of C. arenicola (although I had made sure to capture some live adults for studio shots that night as a backup).  As the sun began sinking in the western sky and temperatures began to cool off, I noticed the adults were becoming scarce and that fresh burrows were appearing on the dune surface.  In contrast to earlier in the day, adult beetles were found in nearly every burrow that I excavated—the beetles were digging in, and if I wanted field photographs it was now or never.  I managed a few distant shots of the first several adults I tried to stalk, but none of these were close to keepers.  I eventually noticed that beetles in the sparsely vegetated areas of the dune seemed to be slightly more approachable than those out on the open dune surface (perhaps they felt a little more secure in the presence of some cover), and although the vegetation often obscured clear views of the beetles, it was at least a more manageable problem than not even being able to approach them.  Finally, after considerable effort, I managed the photograph shown below.  I’d like to take credit for the near perfect composition and focus, but it was an actually a completely accidental shot.  I had been stalking the beetle for some time and had finally gotten closer to it than I had managed for any other beetle.  Rather than a presenting me with a lateral profile, the beetle was directly facing me as I closed in for the shot. Just as I pressed the shutter the beetle turned profile and then darted off.  Other than nipping the middle tarsus I don’t think I could’ve framed this uncropped photo better if I had tried.

Cicindela arenicola | September 2011 | vic. Idaho Falls, Idaho

Cicindela arenicola is closely related to C. waynei (known only from sand dunes in and around Bruneau Dunes State Park in southwestern Idaho), and it is only recently that the two have been considered separate species.  Cicindela waynei differs in its generally green rather than bronze coloration, more expanded white markings, and the presence of a curious upward projecting tooth on the male mandible (Pearson et al. 2006).  There are some populations in south-central Idaho assigned to C. arenicola that show an intergradation of characters between the two species, primarily in the presence of individuals with green coloration and expanded markings, so I found it interesting to encounter just such an individual at this southeastern Idaho site as well.  The individual, a male (and photographed in a terrarium that evening), looks very much like C. waynei except that it lacks the distinctive mandibular tooth characteristic of that species.

Male from same locality with green elytra and expanded markings

Cicindela arenicola is largely restricted to the Snake River Plain of southern Idaho, with a small population also occurring in the Centennial Sandhills of southwestern Montana (Winton et al. 2010). The sand dunes on which these beetles depend have suffered numerous assaults in recent years at the hands of man, with exotic invasives (Bouffard et al. 2009), trampling by cattle (Bauer 1991), and offroad vehicular traffic having the greatest impact on tiger beetle populations.  The species has been considered for listing on the Endangered Species List due to the imperiled nature of its limited habitat, but to this point such status has not yet been accorded.  It has, however, been listed as globally imperiled by the Idaho Department of Fish and Game and the Bureau of Land Management.  Most people are completely unaware that this beetle exists, and probably fewer still would even care.  For me personally, however, the chance to see this rare and beautiful beetle in its native habitat and spend time watching its behavior was a thrill I won’t soon forget.

Tiger beetle's-eye view of its preferred sand dune habitat.

I haven’t forgotten about the challenges that led to this post.  However, the hour is late and I need my rest.  Points will be awarded over the next day or so, and the winner of BitB Challenge Session #4 will be crowned!  In the meantime, I’ve released the submitted comments so you can see how your answers fared against the competition—no do-overs!

REFERENCES:

Bauer, K. L. 1991. Observations on the developmental biology of Cicindela arenicola Rumpp (Coleoptera: Cicindelidae). Great Basin Naturalist 51:226–235.

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.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States & Canada: Identification, Natural History, and Distribution of the Cicindelidae. Oxford University Press, New York, NY. 227 pp.

Rumpp, N. L. 1967. A new species of Cicindela from Idaho (Coleoptera: Cicindelidae). Proceedings of the California Academy of Science 35:129–140.

Winton, R. C., M. G. Kippenhan and M. A. Ivie.  2010.  New state record for Cicindela arenicola Rumpp (Coleoptera: Carabidae: Cicindelinae) in southwestern Montana.  The Coleopterists Bulletin 64(1):43–44.

Copyright © Ted C. MacRae 2011

Lytta vulnerata cooperi

Lytta vulnerata cooperi | Idaho Falls, Idaho

I had other quarry on my mind when I visited Idaho a couple of weeks ago, but I couldn’t help but pay attention to this blister beetle (family Meloidae) feeding on rabbit brush flowers for the following two reasons: 1) its spectacular and boldly contrasting black and orange coloration, and 2) my collecting partner, Jeff Huether, is an expert on North American Meloidae. My identification of this individual as Lytta vulnerata is based strictly on one line of evidence: Jeff said that’s what it is!  My further identification as the subspecies L. vulnerata cooperi is more tenuous, being based on the distinctly sculptured elytra, immaculate pronotum, and more northerly location (nominotypical individuals, at least from what I can tell looking at photos assigned to the two subspecies, have the elytra indistinctly sculptured, generally exhibit a median line or vitta on the pronotum, and occur further south).

Note distinct elytral sculpturing and immaculate pronotum

Copyright © Ted C. MacRae 2011

Bruneau Sand Dune tiger beetles caught in the act!

ResearchBlogging.orgThe newest issue of CICINDELA (“A quarterly journal devoted to Cicindelidae”) contains an interesting article by my good friend and fellow tiger beetle enthusiast Kent Fothergill, who presents a fascinating sequence of photos documenting a field encounter with a mating pair of the endangered Bruneau Sand Dune tiger beetle (Cicindela waynei) (Fothergill 2010).  This is one of several tiger beetle species in the C. maritima species group that inhabit sand dunes in central and western North America – others include the Coral Pink Sand Dune tiger beetle (C. albissima), the St. Anthony Sand Dune tiger beetle (C. arenicola), the Colorado dune tiger beetle (C. theatina), and the sandy tiger beetle (C. limbata).  With the exception of the latter, these species show highly restricted distributions in their preferred sand dune habitats, and because their populations are so small they are especially vulnerable to drought and ever-increasing anthropogenic pressures (i.e., invasive plants, motorized vehicular traffic, overzealous collectors).  While the Bruneau Sand Dune tiger beetle has not been accorded status on the Endangered Species List, the Idaho Department of Fish and Game and the Bureau of Land Management have classified it as globally imperiled.

Bruneau Sand Dune tiger beetle, Bruneau Sand Dune State Park, Idaho. Photo © Kent Fothergill 2009.

Kent was observing these beetles in Bruneau Dune State Park in southwestern Idaho – the main habitat for this species – when he encountered several pairs of C. waynei in the process of mating.  Photographs were taken of one mating pair, revealing a fascinating sequence of behaviors that included vigorous but unsuccessful attempts by the female to dislodge the male, eversion and penetration of the female by the male aedeagus, and subsequent mate guarding (see photo above).  It is, in fact, this latter behavior that is most often observed among tiger beetle mating pairs and not actual mating itself, which is only rarely observed.  Kent noted the uniquely modified male mandibles (see photo below) and their possible role in preventing the male from being dislodged during the female’s initial protestations.

Male Bruneau Sand Dune tiger beetles sport impressive choppers! Photo © Kent Fothergill 2009.

This apparently is the first documented report of mating in this species, and its occurrence in May is considerably later in the season than Baker et al. (1997) speculated – significant because protection of 1st instar larvae is a management priority for conservation of this species.  The potential occurrence of 1st instars during a longer period of time is an important consideration for continued management of this species, as the Bruneau Sand Dune population continues to show evidence of decline despite the prohibition of insect collecting, cattle grazing, and off-road vehicles within the park (Bosworth et al. 2010).  Human trampling and pesticide applications to adjacent rangelands are continuing threats that have proven more difficult to manage.

My sincerest thanks to Kent Fothergill for presenting me the opportunity to review his manuscript prior to publication and allowing me to reproduce here two of his spectacular photographs of this gorgeous and rare species.

REFERENCES:

Baker, C. W., J. C. Munger, K. C. Cornwall and S. Staufer.  1997. Bruneau Dunes tiger beetle study 1994 and 1995.  Idaho Bureau of Land Management, Technical Bulletin 97-7, 52 pp.

Bosworth, W. R., S. J. Romin and T. Weekley.  2010. Bruneau Dunes tiger beetle assessment.  Idaho Department of Fish and Game, Boise, Idaho, 36 pp.

Fothergill, K.  2010. Observations on mating behavior of the Bruneau Dune tiger beetle, Cicindela waynei Leffler (Coleoptera: Carabidae: Cicindelinae).  CICINDELA 42(2):33–45, 7 color plates.

Copyright © Ted C. MacRae 2010

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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

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.

REFERENCES:

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

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