Beetle Research Roundup

Third-instar larva of Megacephala megacephala (Olivier), photographed near a light trap on 17 July 2006 in Coli, Quebo, Guinea-Bissau, Africa, by Artur R. M. Serrano.The latest issue of the journal Cicindela arrived in my mailbox today, and as usual some interesting papers are included.  For those of you unfamiliar with it, Cicindela is “a quarterly journal devoted to the Cicindelidae,” publishing papers dealing with any aspect of the study of tiger beetles. Founded in 1968 by North American tiger beetle experts Ronald L. Huber, Robert C. Graves, and Harold L. Willis, it was dubbed in those early issues as “…an experiment—an inquiry into the merits (and shortcomings?) of extreme specialization…”. Richard Freitag succeeded Willis in 1975, and that trio has edited and produced this “experiment”—now in its 41st year—ever since!  Issues are available for a very nominal $10 per year ($13 outside of the U.S.).  My sincere thanks to Artur Serrano (University of Lisbon) for permitting me to post his stunning photograph of the third-instar larva of Megacephala megacephala, photographed in Guinea-Bessau, Africa and gracing the cover of this latest issue.

Tetracha virginica in Wisconsin
Despite the common occurrence of this species across the southern two-thirds of the eastern U.S., its northern and western limits of distribution are still poorly known.  Grimek discusses records of this species in Wisconsin during the 45-year period between 1962 to 2007, noting that all of the captures were from sandy areas near rivers in, with the exception of a single specimen, the “Driftless Area” covering the southwestern quadrant of the state.  (The Driftless Area, also called the Paleozoic Plateau, is an area that escaped glaciation during the last glacial period).  The capture of a specimen very near the Mississippi River suggests the species may also be found in Minnesota, where its occurrence has not yet been documented.

Grimek, H.  2009.  Distribution of Tetracha virginica (Linnaeus) in Wisconsin.  Cicindela 41(3):57-61

Brasiella cuyabaensis in Bolivia
Brasiella is a large genus (47 species) of small to very small, mostly Neotropical tiger beetles, of which B. argentata is among the most common and widespread.  While examining specimens of this species that he had collected in Bolivia, Italian coleopterist Fabio Cassola found a second species among the material.  At first thought to potentially represent a new species, its identity was ultimately revealed after examination of the unique male type specimen of B. cuyabaensis from Brazil.  This specimen is very similar to B. argentata except for its genitalia (longer and narrower than in B. argentata), and Cassola has confirmed this in his material as well.  The previously unknown females were especially problematic; however, Cassola found their longer, more convex labrum (upper lip) to be a useful diagnostic character.  Cassola collected B. cuyabaensis some 700 km west of the type locality and speculates that additional specimens of the species may exist in entomological collections, incorrectly placed under B. argentata.

Cassola, F.  2009.  Studies of tiger beetles.  CLXXV.   Occurrence in Bolivia of Brasiella cuyabaensis (Mandl, 1970) (Coleoptera: Cicindelidae).  Cicindela 41(3):63-67.

DNA degrades rapidly in pinned tiger beetles
DNA molecular analyses are increasingly being used to elucidate relationships among tiger beetles, both at the species level and at higher levels of classification.  However, such research is often hampered by the limited availability of sufficient fresh material representing less common taxa.  Pinned museum specimens offer a potential source of DNA for such uncommon taxa; however, successful extraction of useable DNA from pinned specimens has been limited.  Kritsky and Duennes, using a standardized DNA extraction method, determined that DNA extracted from pinned tiger beetles rapidly degrades during the first 25 years after collection before stabilizing at ~10% of the original DNA.  The authors found that frozen specimens yeilded more DNA than specimens killed in ethanol, perhaps due to degradation of DNA by water in the ethanol, and noted that choice of killing method and use of fumigants during storage can also contribute to loss of DNA.  More research is needed to determine optimal conditions for protecting museum specimens while preserving their DNA for future research.

Kritsky, G. and M. Duennes.  2009.  The rate of DNA degradation in pinned tiger beetles.  Cicindela 41(3):69-73.

Mississippi tiger beetles scavenge dead fish
An established breeding population of Cicindela pamphila [= Habroscelimorpha pamphila] was observed during 2006–2008 in a Mississippi coastal salt marsh.  This species was previously considered a rare straggler into Mississippi, occurring primarily along the Texas Gulf Coast south into Mexico.  The Mississippi population was observed co-occurring with C. hamata [= Ellipsoptera hamata], C. severa [= Habroscelimorpha severa], and C. togata [= Eunota togata].  On one occasion, individuals of C. hamata and C. severa were observed feeding on a fresh mullet (Mugil sp.) carcass resulting from a raptor kill, adding these two tiger beetle species to the list for which scavenging on dead vertebrates has now been confirmed.  Despite the co-occurrence of four species of tiger beetles within this area, the author noted no apparent resource partioning and speculates that carrion resulting from predation by birds, racoons, etc. may provide a valuable resource for scavenging tiger beetles that reduces competition for food.

Grammer, G. L.  2009.  A breeding population record of Cicindela pamphila in Mississippi and observations on the scavenging behavior of C. severa and C. hamataCicindela 41(3):75-80.

Copyright © Ted C. MacRae 2009

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Goldenrod Leaf Miner


Photo details: Canon MP-E 65mm macro lens on a Canon EOS 50D, ISO 100, 1/200 sec, f/16, MT-24EX flash 1/8 power through diffuser caps

While photographing Acmaeodera tubulus and A. ornata a couple of weekends ago (see Springtime Acmaeodera), I came across this leaf beetle (family Chrysomelidae) of the genus Microrhopala¹.  When I took Systematic Entomology (so many moons ago), beetles in this and related genera were placed in the subfamily Hispinae.  That taxon has since been subsumed by a more broadly defined Cassidinae (Staines 2002), which also includes the delightfully odd tortoise beetles.  There are several species of Microrhopala in North America – this individual can be diagnosed as M. vittata by means of its dull reddish elytral stripes, eight-segmented antennae, and smooth (not serrate or toothed) elytral margins (Clark 1983). 

¹ Derived from the Greek micr (small) and rhopal (a club) – presumably a reference to its small-clubbed antennae.

Many leaf beetles are expert botanists, restricted to and able to discriminate a single plant species or group of closely related species for hosts.  Microrhopala vittata is no exception, specializing on true goldenrods (Solidago spp.) and flat-topped goldenrod (Euthamia graminifolia) (family Asteraceae).  Adults feed on leaves in the upper part of the plant, leaving numerous small holes, but it is the larvae that have the biggest impact on their host by mining within the leaves between the upper and lower surfaces.  Larval mining eventually causes the leaves to turn brown and shrivel up. 

This species has been widely studied by ecologists interested in understanding the impacts of herbivorous insects on their host plants and associated changes to plant communities that result from their feeding.  While population densities of M. vittata are normally low, they occasionally reach densities that result in severe damage to their host plants.  Such effects are not limited to the host plants themselves – Carson and Root (2000) found that outbreaks of this species on stands of tall goldenrod (Solidago altissima) in an old field dramatically reduced the biomass, density, height, survivorship, and reproduction of tall goldenrod, resulting in higher abundance, species richness, and flowering shoot production among other plant species as a result of increased light penetration.  Conversely, in experimental plots where the beetles were removed, tall goldenrod developed dense stands that inhibited the growth of many other plants.  These effects lasted for several years after the outbreak.  Thus, the beetle can act as a keystone species² in old field communities, indirectly promoting woody plant invasion and speeding the transition of the old field to a tree-dominated community.

² A keystone species is one whose impacts on its community or ecosystem are large and greater than would be expected from its relative abundance or total biomass (Paine 1969).  Popular examples include the beaver, which transforms stream communities to ponds or swamps, and elephants, which prevent grasslands from converting to woodlands through destructive tree removal.  In contrast, trees, giant kelp, prairie grasses, and reef-building corals all have impacts that are large but not disproportionate to their also large total biomass and, thus, are not considered keystone species.


Carson, W. P. and R. B. Root.  2000.  Herbivory and plant species coexistence: Community regulation by an outbreaking phytophagous insect.  Ecological Monographs 70(1):73-99.

Clark, S. M. 1983. A revision of the genus Microrhopala (Coleoptera: Chrysomelidae) in America north of Mexico. The Great Basin Naturalist 43(4):597-617.

Paine, R. T. 1969. A note on trophic complexity and community stability. The American Naturalist 103(929):91–93.

Staines, C. L. 2002. The New World tribes and genera of hispines (Coleoptera: Chrysomelidae: Cassidinae). Proceedings of the Entomological Society of Washington 104(3): 721-784.

Copyright © Ted C. MacRae 2009

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