Monday, July 21, 2014

The Inexplicable Mojo of Tiger Beetles.

Horn's Tiger Beetle, Cicindela (Cicindelidia) hornii Schaupp.
A Rebuttal.

mo-jo - noun.
1. A magic charm, talisman, or spell.
2. Magic power.

Based on a recent perusal of current literature and various internet sources, it appears that some information concerning the behavior, seasonality, alleged rarity, and color forms of Cicindela (Cicindelidia) hornii Schaupp warrant further discussion. Apparently, a great deal of this information and supposition is based upon brief incidental field collections - or lack of - and observations. For most collectors and students of tiger beetles, this species is a fortuitous hit-or-miss opportunity - a collateral species. As a result, it carries an exaggerated distinction as being a rare and highly coveted species.

Typical habitat of Cicindelidia hornii Schaupp
Upper Sonoran Mesquite-Grassland
Sulphur Springs Valley, Cochise County, Arizona
Alleged rarity. 
The term rare is so commonly used (= misused) in entomology, that in fact, it has lost its connotation. Remember, when dealing with things biological - anything is possible. Consider that beetles, and insects in general, emerge and become active when a certain combination of physiological and environmental stimuli are reached (for example, moisture, temperature, humidity) indicative of phenotypic plasticity: any change in an organism’s characteristics in response to an environmental signal (Schlichting and Smith 2002:190).

In southwestern North America, moisture, in the form of either winter rain or summer monsoons, is an essential factor in this equation. Without this necessary moisture insects may delay their emergence for several months or years. My point being, there are prevailing factors that influence, or deter, fecundity (abundance), of an organism - despite the exhortations of frustrated collectors.

Another habitat photo of Cicindelidia hornii Schaupp
Upper Sonoran Mesquite-Grassland
Sulphur Springs Valley, Cochise County, Arizona
Behavior & Seasonality. 
In southeast Arizona, C. hornii emerges during the summer monsoon that typical begins in late June or early July. It is best described as an ephemeral species because it is active while the soil remains damp after rainfall. Once this moisture evaporates, it disappears along with several other sympatric species, such as Cicindela pulchra dorothea Rumpp (below, left). Cicindelidia hornii typically occurs in grassy pastures and roadsides where it will hide in the shade beneath grass clumps or other vegetation during morning to mid-day hours or seen running in open areas in search of prey.

Cicindela pulchra dorothea Rumpp
Polymorphism: Color Variation.
Polymorphism is the occurrence of more than one color form, or morph, in the same population of a species. Of the various publications and websites that display images of C. hornii, usually only one or two color forms are illustrated. Based on specimens in my collection, iridescent metallic blue, blue-green head and pronota with purple elytra, blue-green to green, and black are represented. The latter melanistic form being the most commonly encountered. Although anecdotal, from my field observations, it appears that the more brilliantly colored individuals appear earlier in the season. Victor E. Shelford, in his treatise, Color and color-pattern mechanism of Tiger Beetles (1917), noted that tiger beetle coloration was influenced, in part, by climatic conditions.

Color variation of Cicindelidia hornii Schaupp:
blue, bluegreen head & pronota with purple elytra, bluegreen-green, black.
Sulphur Springs Valley, Cochise County, AZ

Literature Cited

Schlichting, C. D., and H. Smith. 2002. Phenotypic plasticity: linking molecular mechanisms with evolutionary outcomes. Evolutionary Ecology 16:189–211

Shelford, V. E. 1917. Color and color-pattern mechanism of tiger beetles, with twenty-nine black and three colored plates.Volume Illinois Biological Monographs Vol.3: No. 4

                                                          Other Suggested Reading

Bertholf, J.K. 1979 (MS Thesis). Tiger Beetles of the genus Cicindela in Arizona (Coleoptera:Cicindelidae). 1983 (paperbound edition). Texas Tech University Special Publications, Texas Tech Press, Lubbock, Texas. #19:1-44.  .pdf 
Schultz, T.D., and N. F. Hadley. 1987. Structural Colors of Tiger Beetles and Their Role in Heat Transfer through the Integument. Physiological Zoology. 60 (6):737-745

                                           © Delbert La Rue 2014. All Rights Reserved.       

Wednesday, July 16, 2014

Adventures in Acmaeoderini.
Déjà vu all over again:
Granite Gap, Peloncillo Mountains, Hidalgo Co., New Mexico

With its spectacular granite boulders, limestone outcrops and diversity of floristic types, the area is a classic example of the Chihuahuan Desert. It has a higher cactus diversity than any other area in New Mexico. Because of its biological and scenic beauty, Granite Gap is designated by the BLM as an Area of Critical Environmental Concern. Access is strictly limited to designated roads and trails.

Note burned Prosopis in foreground

From the literature and personal collection records, at least 9 species of Acmaeoderini have been recorded from the site and surrounding area:

    Adult host association(s) [in part].

Acmaeodera cazieri Knull,
    Cirsium sp., Argemone sp. (Knull 1960:7); on flowers Jatropha macrorhiza (MacRae & Nelson 2003:58).

Acmaeodera davidsoni Barr (Type Locality),
   Acacia constricta, A. greggii, Mimosa biuncifera (Barr 1972:180); Prosopis sp. (Bellamy 1982:359).

Acmaeodera delumbis Horn,
    Acacia constricta  (Westcott, et al. 1979:173).

Acmaeodera parkeri Cazier,
    Allionia incarnata (Westcott, et al. 1979:177); Haplopappus sp., Boerhaavia coccinea (Bellamy 1982:359).
Acmaeodera pinalorum Knull,
    Mimosa biuncifera (Walters & Bellamy 1990:113).

Acmaeodera quadrivittatoides Nelson & Westcott,
    Adults have been recorded on a wide variety of flowers (Nelson & Westcott 1995:81).
    At this locality, I have collected this species on Alliona incarnata flowers.

Acmaeodera yuccavora Knull,
    Alliona incarnata (Westcott, et al. 1979:180).
    Adults frequently alight on paths or other bare areas (Knull 1962:3).
    At this locality, I have collected this species on Alliona incarnata flowers.

Acmaeoderopsis hulli (Knull),
    Mimosa sp., Prosopis glandulosa (Nelson & Westcott 1976:274).
Acmaeoderopsis rockefelleri (Cazier),
    Acacia constricta, Prosopis juliflora (Nelson & Westcott 1976:274).  

The distribution of Acmaeodera gibbula LeConte overlaps this area suggesting it may also occur here.

The flight period of these species is typically during the months of June through August, in some years earlier (April, May) or later (September). Emergence probably depending upon mean temperature and monsoonal precipitation. The distribution of a few of these species continues south along NM 80 on associated hosts.

Field notes 15.VII.2014.
Subsequent to my visit on 17.VII.2010, the area appears to have been burned. Most of the Prosopis and Acacia are growing back. On this visit, monsoons had drenched the area within the last few days. Some of the Acacia and Larrea were just beginning to bloom but I was unable to locate any Alliona where they grew on my prior visit.

Alliona incarnata

Internet resources and literature cited.

A Synopsis of the Adult and Larval Plant Associations for New World Acmaeoderini (Coleoptera: Buprestidae)

Barr, W. F. 1972. New species of North American Acmaeodera (Coleoptera: Buprestidae). Arquivos do Museo Boçage 2.a Série, 3(7):145-202. .pdf

Bellamy, C. L. 1982. Observations on the biology and distribution of several species of Buprestidae (Coleoptera) of North America. The Coleopterists' Bulletin 36(2):358-361. .pdf

Knull, J.N. 1960. A new subspecies of Acmaeodera quadrivittata Horn (Coleoptera:Buprestidae). The Ohio Journal of Science. 60(1): 6-7. .pdf

Knull, J.N. 1962. A new yucca-inhabiting Acmaeodera from Arizona (Coleoptera:Buprestidae). The Ohio Journal of Science. 62(1): 2-3. .pdf

MacRae, T. C., & G.H. Nelson. 2003. Distributional and biological notes on Buprestidae (Coleoptera) in North and Central America and the West Indies, with validation of one species. The Coleopterists' Bulletin, 57(1): 57–70. .pdf

Nelson G.H., & R.L. Westcott 1976. Notes on the distribution, synonymy, and biology of Buprestidae (Coleoptera) of North America. The Coleopterists' Bulletin. 30(3):273-284. .pdf

Nelson G.H., & R.L. Westcott 1995. Three new species of Acmaeodera Eschscholtz (Coleoptera:Buprestidae) from the United States and Mexico. The Coleopterists' Bulletin. 49(1):77-87. .pdf

Walters, G.C., & C.L. Bellamy 1990. Notes on the distribution and biology of certain Buprestidae (Coleoptera): Part IV. The Coleopterists' Bulletin. 44(1):113-115. .pdf

Westcott, R. L., W. F. Barr, G. H. Nelson, & D. S. Verity. 1979. Distributional and biological notes on North and Central American species of Acmaeodera (Coleoptera: Buprestidae). The Coleopterists' Bulletin 33(2):169-181. .pdf

Aerial photo courtesy of  The Sky Gypsies.

© Delbert La Rue 2014. All Rights Reserved.

Monday, July 7, 2014

Cochise Stronghold, Dragoon Mountains, Cochise County, Arizona

 Trachyderes (Dendrobias) mandibularis Dupont on Baccharis ssp.

© Delbert La Rue 2014. All Rights Reserved.