Month: February 2012

The “Big 3” of corn in Argentina

/ Ted C. MacRae / 8 Comments

While leafcutter ants are one of the more unusual pests that Argentina corn farmers must deal with, the three most important confront farmers throughout the Western Hemisphere: stalk borers, earworms, and armyworms. In the U.S. the primary stalk boring pest of corn is the European corn borer (Ostrinia nubilalis), while in Argentina it is the sugarcane borer (Diatraea saccharalis). Corn earworm (Helicoverpa zea) and fall armyworm (Spodoptera frugiperda), on the other hand, are common to both countries. Here are some recent photos of the three species in Argentina – the first two on corn and the latter on soybean.

After you look at the photos, I have a funny story…

Diatraea saccharalis eggs ready to hatch | Buenos Aires Prov., Argentina

Helicoverpa zea egg on corn silk | Buenos Aires Prov., Argentina

Spodoptera frugiperda mid-instar larva on soybean | Buenos Aires Prov., Argentina

Learning to speak a foreign language via immersion can result in some embarrassingly funny moments. This afternoon I made an unplanned visit to the field with some colleagues. There has been much rain recently so the ground was rather muddy. Not having my boots with me, I picked my way through as best I could, and afterwards as I was cleaning the mud off my shoes, I commented (in Spanish) to one of my Argentine colleagues (a young female) that this was my only pair of clean shoes. I said everything okay but messed up the word for shoes—instead of saying “calzados” I said “calzones.”

In Argentina, calzones means “underwear.”

I’m really glad the shocked look on her face quickly gave way to hysterical laughter once she figured out what I was trying to say.

Copyright © Ted C. MacRae 2012

Leafcutter ants on corn

/ Ted C. MacRae / 7 Comments

Leafcutter ants attacking corn | western Buenos Aires Prov., Argentina

North American corn farmers certainly have their share of insect pests to worry about. Between corn borer, earworm, armyworm, and rootworm, there isn’t much of the plant that isn’t vulnerable to attack by at least one of these insects. Argentina corn farmers have all this and more—have you ever seen ants attacking corn? I took these photographs yesterday in a corn field in western Buenos Aires Province showing leafcutter ants dining on the developing kernels of late-planted corn. Okay, “dining” may not be the proper word, as they are not actually eating the kernels, but rather harvesting them to bring them back to their “hormiguera” (ant nest) for cultivation of the fungi on which they feed. The four pairs of spines on the pro-mesonotum and narrow distal antennal segments suggest this is a species of Acromyrmex, three species of which are mentioned as pests of corn in Argentina (A. lundii, A. striatus, and A. lobicornis). Of these, the individuals in these photos seem to best match AntWeb’s photos of Acromyrmex lundii, but that is just my guess.

Acromyrmex sp. poss. lundii?

Copyright © Ted C. MacRae 2012

To the land of Gauchos

/ Ted C. MacRae / 10 Comments

Today I leave for an extended stay in Argentina. Many have asked me if my trip is for work or fun, and my standard response has been, “It’s for work, and it will be fun!” For the next eight weeks, I’ll be helping out with field trials and speaking to farmers (while sampling a few Malbecs as well). Of course I would rather it be an 8-week collecting trip, but I consider myself fortunate even to have an opportunity such as this. I’ll pick up a few insects along the way, but what I really hope to bring back in large quantity is photographs.

It’s a little difficult to predict how reliable and consistent I’ll have internet access or the time to take advantage of it, so postings over the next few weeks may be a little less regular than what has become my usual custom. The trip is also heavily front-loaded with work activities as I get my bearings and spend time getting to know my new colleagues, so I’m not sure when I might have new photos to show here. Not to worry, I have plenty of material that I haven’t yet shown. Until then, I leave you with this photograph I took last November at  in Buenos Aires. These tiny bugs seem to be early-instar leaf-footed bug (family Coreidae) nymphs, their bright red and black coloration and aggregating behavior indicating ample chemical protection against predation.

Early-instar coreid nymphs | Buenos Aires, Argentina

Copyright © Ted C. MacRae 2012

Chrysobothris viridiceps

/ Ted C. MacRae / 9 Comments

Chrysobothris viridiceps on dead branch of Quercus alba | Baxter Co., Arkansas

Despite their general popularity among beetle collectors, jewel beetles (family Buprestidae) have an admittedly deserved reputation for difficult taxonomy. Part of the reason for this is the existence of several highly speciose genera. In North America, for example, nearly half of its described species belong to just three genera—Acmaeodera, Chrysobothris, and Agrilus (the latter, with nearly 3,000 described species and many more awaiting description, being possibly the most speciose animal genus in the world). Identification of species within these genera is difficult enough due to their sheer numbers and is further complicated by the existence a number of “species-groups”—i.e., groups of very closely related species that have only recently become reproductively isolated from each other (likely in response to host partitioning) but have not yet evolved obvious unique morphological characters. Perhaps the most famous of these is the “Chrysobothris femorata species-group.” A dominant component of hardwood forests throughout North America, members of this group have confounded taxonomists, collectors, and foresters alike for many years. Fortunately, the recent revision of the group and formal description of several species by Wellso and Manley (2007) have brought much needed clarity to the group. While problems still remain (C. femorata sensu novo probably still encompasses several undescribed species), most individuals can now be identified with some confidence.

Males and females both exhibit completely divided post-median fasciae

I have previously discussed three of the seven now recognized species occurring broadly in eastern North America—the nominate C. femorata, still regarded as an important pest of ornamental and fruit tree plantings, C. caddo, one of the new species described by Wellso and Manley (2007) and associated with dead hackberry (Celtis spp.), and C. quadriimpressa, mostly associated with dead branches of oak (Quercus spp.). The individuals shown here, photographed on branches of a dead white oak (Quercus alba) in north-central Arkansas this past June, represent a fourth species in the group, Chrysobothris viridiceps. Unlike most members of the C. femorata species-group, C. viridiceps can be readily recognized in the field  due to the uninterrupted costa (raised narrow ridge) that completely bisects the posterior fovea (rounded pit) on each elytron. In all other species this costa is interrupted by the fovea. Moreover, this species is the only one in the group in which the males (easily distinguished from females by the bright green frons, or face) exhibit bicolored antennal segments, with the outer portion of each segment yellow and the remainder bright metallic green. While the species name is Latin for “green face,” this character is useless for species identification, as males of all species in the group exhibit a more or less green face.

Males sport not only the green face for which the species is named, but also distinct yellow areas on the antennal segments

Females are a little more difficult to distinguish in the field because, like those of other species of the group the antennae are more uniformly reddish. Likewise, the face also lacks the green coloration of the male, and although still useful for species identification the differences among females between the different species are more subtle and require microscopic examination. However, as in the male the elytral foveae are completely divided, allowing even females to be recognized relatively easily.

Females tend to be more reddish on the legs, antennae and face

One thing I have noticed about the different members of the C. femorata species-group is the usefulness of host plant association in distinguishing the different species. Of the seven species occurring in my region, I’ve seen C. femorata associated mostly with stressed but still living trees in genera other than oak or hickory (e.g., maple, sycamore, apple, poplar, ash, etc.), C. adelpha associated exclusively with dead hickory (Carya spp.), and C. caddo associated almost exclusively with hackberry (Celtis spp.). The remaining four species are all associated primarily or exclusively with oaks, but even these species often segregate according to branch size, with C. viridiceps occurring mostly on the smallest branches, C. quadriimpressa on somewhat larger branches, C. rugosiceps on very large branches and the upper trunk, and C. shawnee on large trunks and even stumps. Not surprisingly, these size preferences reflect the relative size of the beetles, with C. viridiceps (7–13 mm in length) generally being the smallest of the four species and C. shawnee (9–18 mm in length) the largest.

Okay, now to get photos of C. adelpha, C. rugosiceps and C. shawnee!

REFERENCES:

Wellso, S. G. and G. V. Manley. 2007. A revision of the Chrysobothris femorata (Olivier, 1790) species group from North America, north of Mexico (Coleoptera: Buprestidae). Zootaxa 1652:1–26.

Copyright © Ted C. MacRae 2012

Grampus and go-devil

/ Ted C. MacRae / 19 Comments

Corydalus cornutus | Wayne Co. Missouri


Ever taken a close look at a female dobsonfly’s head? Female dobsonflys don’t get nearly as much attention as the males due to the latter’s ridiculously elongated mandibles. While female mandibles are more modestly proportioned, don’t think they’re ineffectual—females are quite capable of inflicting a blood-letting nip if one is not careful. Certainly the female head is no less dinosaurian in appearance than the male’s, and while I know that Corydalus cornutus is the product of the same amount of evolutionary time as any other species on earth today, I can’t help but think they look so “primitive.”

While dobsonfly is the commonest name applied to these insects, I much prefer “go-devil” (not sure of the origin) and “grampus” (from “Krampus”—a mythical horned, creature in Alpine countries). The latter name in particular pays more appropriate homage to the monstrous appearance of these insects.

Photographed July 2011 at a blacklight sheet in Sam A. Baker State Park, Wayne Co., Missouri.

Copyright © Ted C. MacRae 2012

Tiger beetles in southeast Missouri

/ Ted C. MacRae / 6 Comments

Figure 1. Sites surveyed in southeastern Missouri for Cylindera cursitans during 2007–2010. Site numbers are referenced in Table 1 (CRP = Cape Rock Park), with red stars indicating sites where C. cursitans was observed. Black box on inset map of Missouri denotes main map area (bordering states include AR to the south and TN, KY, and IL to the east).

ResearchBlogging.orgVolume 43(3) of the journal CICINDELA was published a few weeks ago, and I can truly lay more claim to the issue than anybody else (except perhaps Managing Editor Ron Huber). In addition to having one of my photos (a face-on shot of Tetracha carolina) featured on the cover, I was coauthor on the first of two papers included in the issue and lead author on the second. (And to complete my stamp of ownership, I did the final assembly of the issue as the journal’s Layout Editor.) The two included papers each report the results of surveys conducted in the Mississippi Alluvial Plain of southeastern Missouri (also called the “bootheel” in reference to its shape—see Fig. 1) for tiger beetles whose occurrence in that part of the state was previously not well known. In the first, Fothergill et al. (2011) used a novel survey technique that involved searching beneath irrigation polypipe in agricultural fields to find Tetracha carolina (Carolina Metallic Tiger Beetle); while the second paper (MacRae et al. 2011) reports the results of a multi-year survey to characterize the distribution, habitat associations and conservation status of Cylindera cursitans (Ant-like Tiger Beetle). Together with our three papers on Habroscelimorpha circumpicta johnsonii (Saline Spring Tiger Beetle), Dromochorus pruinina (Loamy Ground Tiger Beetle) and Cylindera celeripes (Swift Tiger Beetle)—all published in the past year—these two papers officially complete the battery of publications that describe our survey efforts for the five tiger beetle species considered of potential conservation concern in Missouri when Chris Brown and I began our faunal studies of the group more than ten years ago.

The first three papers clearly painted a rather gloomy picture—H. circumpicta johnsonii is possibly extirpated from saline spring habitats in central Missouri, D. pruinina is limited to a 2.5 mile stretch of roadside habitat in western Missouri, and C. celeripes is restricted to a few patches of critically imperiled loess hill prairie habitat in extreme northwestern Missouri. Happily, prospects for T. carolina and C. cursitans in Missouri are much better. While both are limited in the state to the southeastern lowlands, our surveys indicated that populations are sufficiently robust and widespread in the area to alleviate any concerns about the potential for extirpation. Tetracha carolina in particular was found abundantly in agricultural habitats and appears to have adapted well to the extensive modifications caused by conversion of the cypress-tupelo swamps that formerly covered the region. Cylindera cursitans (Fig. 2) hasn’t shown nearly the same adaptive capability as T. carolina; however, it has nevertheless found suitable refuge in the ribbons of wet, bottomland forest that persist between the Mississippi River and the levee systems that protect the region’s farmland. For a time it seemed that the same habitats along the St. Francois River that bound the western side of the region weren’t suitable for the species, but after much searching (in often tough conditions!) Kent finally managed to locate a population on the Missouri side of the river opposite a known population in Arkansas.

Figure 2. Cylindera cursitans in southeast Missouri: a) New Madrid Co., Girvin Memorial Conservation Area, 6.vii.2007; b-c) Mississippi Co., Dorena Ferry Landing, 6.vii.2008; d) Mississippi Co., Hwy 60 at Mississippi River bridge, 20.vi.2009. Photos by CRB (a) and TCM (b-d).

Both of these species illustrate how healthy populations of insects are able to hide right beneath our noses. Previous to our surveys, records of T. carolina and C. cursitans in southeastern Missouri were scarce (the latter consisting of a single specimen in the Enns Entomology Museum at the University of Missouri in Columbia, and with considerable searching required before the first field population was finally located). In both cases, perceived rarity was a result not of actual rarity, but rather specific habitat requirement or unusual behavior. While I get great satisfaction out of finding populations of “rare” species and increasing our understanding of their habitat requirements, I also can’t help but wonder if they truly are rare and how many populations I might still have missed—populations that I would have found had I searched in a slightly different manner or at a slightly different time.

REFERENCES:

Fothergill, K., C. B. Cross, K. V. Tindall, T. C. MacRae and C. R. Brown. 2011. Tetracha carolina L. (Coleoptera: Cicindelidae) associated with polypipe irrigation systems in southeastern Missouri agricultural lands. CICINDELA 43(3):45–58.

MacRae, T. C., C. R. Brown and K. Fothergill. 2011. Distribution, seasonal occurrence and conservation status of Cylindera (s. str.) cursitans (LeConte) (Coleoptera: Cicindelidae) in Missouri. CICINDELA 43(3):59-74

Copyright © Ted C. MacRae 2012

The World’s Largest Tiger Beetle

/ Ted C. MacRae / 28 Comments

Manticora scabra - male (L) and female (R) | Republic of South Africa

Some of the first residents of my new insect cabinets (see ) are also among the newest specimens in my collection. Not long ago I received a box from world tiger beetle expert David Brzoska, who had carefully chosen male/female pairs of a number of tiger beetle species from his impressive world collection and sent them to me as a surprise gift. Now, us North America-bound collectors are limited to just a few genera, e.g. Cicindela (although increasingly recognized as a cluster of several closely related genera), Tetracha, and if we’re really lucky Amblycheila and Omus (the last being one I still have not seen in the field). In the rest of the world (especially the tropics and subtropics), however, generic diversity is much higher, and coming as they did from South America, Africa, Australia, and southeast Asia most of the specimens in the sending represented new genera for my collection. While I was grateful for them all, the specimens that had me leaping for joy was this fine pair of Manticora scabra, one of the so-called “African Giant Tiger Beetles.”

Males of all Manticora spp. have asymmetrically enlarged mandibles

In the case of these beetles, the term “giant” is no exaggeration. The male specimen (above and left) measures a full 54 mm (that’s more than 2 inches, folks!) from the tip of its grossly enlarged mandible to the tip of its abdomen, and even the female at 47 mm length is substantially larger than my 38-mm long male specimen of North America’s largest tiger beetle, Amblycheila cylindriformis. While enlarged male mandibles are a common feature among many beetle groups, Manticora males feature an unusual asymmetry in the mandibles, with the right mandible always much larger than the left (itself enlarged compared to the female mandibles, and even the latter cannot be considered small).  Apparently the asymmetry represents a trade-off in natural selection—males use their mandibles not only to hunt prey but also hold onto the female pronotum during mating and subsequent mate guarding. There is positive selection pressure for larger mandible size, as males with smaller mandibles are more likely to be dislodged from the female by competing males. However, because of the large size of the species, larger male mandibles are less effective for securing normal prey items that tend to be smaller in size. If both mandibles were enlarged to the point needed to securely grip the female pronotum, the male would be unable to feed adequately, but having only one mandible fully enlarged provides sufficient grip while maintaining an ability by the somewhat smaller left mandible to grip regular prey items. A consequence of the mandibular asymmetry is that males ride “to the left” when coupled with females.

The right mandible is larger than the left mandible.

David identified these individuals as the species M. scabra, occurring throughout much of southern Africa (Botswana, Malawi, Mozambique, Republic of South Africa, Tanzania, Zimbabwe—according to Carabidae of the World). I presume the species epithet refers to the roughened surface of the elytra. There are at least two recent treatments of the genus (Werner 2000, Mares 2003); however, I have access to neither because of the exorbitant cost of these books—$247 and $433, respectively (I find it rather ironic that the recent explosion of book-sized treatments of “large” beetles has resulted in publications priced so high that they are inaccessible to most professional entomologists).

Female mandibles are nonetheless impressive despite their smaller size.

I made a trip to South Africa in 1999 and had hoped to see these beetles for myself, but unfortunately this did not happen. Perhaps part of the problem was my impression of these beetles as nocturnal hunters—the prevailing ‘wisdom’ at the time. My field partners and I made several nighttime forays in the semi-arid bushveldt where we were camping, using flashlights to scan the ground for any large black beetles we could find moving about. We found numerous tyrant ground beetles (family Carabidae, genus Anthia) and a diversity of tok-tokkies (family Tenebrionidae), but no Manticora tiger beetles. Shortly after that trip, Oberprieler & Arndt (2000) published an informative summary of the biology of several Manticora populations in South Africa, their most notable finding being that adults are opportunistic diurnal predators that hunt by smell rather than nocturnal visual hunters. Perhaps someday I’ll have another opportunity to visit South Africa and see Manticora adults in the field, but until that time I’m happy to have these two specimens residing in my cabinet.

My sincerest thanks to David Brzoska for these sending me these fine specimens and for the many additional kindnesses he has extended to me during the past few years.

REFERENCES:

Mares, J. 2003. A Monograph of the Genus Manticora. Taita Publishers, 205 pp.

Oberprieler, R. G. & E. Arndt. 2000. On the biology of Manticora Fabricius (Coleoptera: Carabidae: Cicindelinae), with a description of the larva and taxonomic notes. Tijdschrift voor Entomologie 143:71–89.

Werner, K. 2000. The Tiger Beetles of Africa (Coleoptera, Cicindelidae) Volume I. Taita Publishers, 191 pp.

Copyright © Ted C. MacRae 2012

Of Bots and Warbles

/ Chris Brown / 14 Comments

As an undergraduate at Truman State University during the mid-90’s I was part of a small mammal research group led by Dr. Scott Ellis.  My focus was on flying squirrels, but others in the group studied mice.  There were always opportunities to help my colleagues trap mice, and that is where I first encountered bot flies (Oestridae: Cuterebra spp.).  It was common for the live trapped mice to be infected with bot fly larvae, or bots, developing just under the skin of the host.  You might expect a fly parasite of a mouse to be relatively small but that is not the case with bot flies.  The bots cause a grotesquely large growth (or warble), and Cramer and Cameron (2006) report that a single bot can weigh as much as 5% of the host body weight.  That’s like a 150 lb guy having a 7.5 lb growth!  One unfortunate mouse that comes to mind had a warble on its head which caused its eye to bulge out.  I hate to make light of that poor mouse’s condition, but I distinctly recall that the bulging eye made it look as if it was continually surprised.  That said, Cuterebra fontinella infections are not thought to have a negative impact on white-footed mice, and in fact some studies have found that infected mice actually live longer than their non-infected neighbors (Cramer and Cameron 2006).  This relatively benign relationship between host and parasite is also the case in general with other species of Cuterebra, which is attributed to the long evolutionary history shared between the parasite and a single or very few closely related hosts (Catts 1982).  Negative impact or not, I was glad that I didn’t have to worry about bot flies infecting me, at least while I was in temperate Missouri.  Of course I had heard plenty of stories of humans being parasitized in the tropics by the human-attacking Dermatobia hominis, and they didn’t sound like very pleasant experiences.  My favorite story involved the person that had a bot in their ear that just about drove them crazy because they could hear the bot any time it changed positions.  Actually the Slansky article discusses the more negative interaction between D. hominis and its host, and this has been attributed to the less specialized relationship between the parasite and any one host because D. hominis has a broad range of hosts. 

Dermatobia hominis actually employ another insect to deliver its eggs to the host!  They lay eggs on mosquitoes or other blood-feeding Diptera for subsequent transfer to the host.  This makes a lot of sense from my point of view as a potential host—the adults are huge (bumble bee size), and I sure would be wary of one approaching me.  But mosquitoes, now there’s an idea—they are very adept at finding their hosts and are inconspicuous enough that they just might be able to get in close enough to allow the body heat of the host to stimulate the hatching and deposition of a bot.

There are other species of Cuterebra, and each is host specific to some degree.  Cuterebra abdominalis (Fig. 1) and Cuterebra buccata are both specific to lagomorphs (rabbits).  No doubt male tree squirrels and chipmunks get a little nervous every time they hear the species name of their bot fly—“emasculator”.  The species name originated from the observation that the warbles were often located near the genitalia of the squirrels, which prompted the idea, given the impressive size of the warble, that there must be an impact on the reproductive ability of the afflicted squirrels.  Luckily for the squirrels, research has demonstrated that the species name is a misnomer (Catts 1982).

Figure 1. Cuterebra abdominalis, a rabbit bot fly

I knew nothing of the adult Cuterebra at the time I saw the parasitized mice, but that changed when Ted MacRae netted an adult rabbit bot fly, Cuterebra buccata, while we were looking for tiger beetles in northeastern Missouri.  In May of 2006, my wife Jess and I came across an adult C. abdominalis on the edge of a glade at Shaw Nature Reserve near St. Louis, and it is this photo that I discuss more below (Fig. 1).  The only other encounter was from southeastern Missouri in April of 2009 when Ted again found a rabbit bot fly, and this individual had only recently emerged from its puparium (Figs. 2 and 3– See Ted MacRae’s previous post from 2009 on this exact same fly).  All told, that’s only three encounters with adult bot flies from countless hours spent in the field, so my experience is that adult bot flies are rarely encountered.

Figure 2. Newly emerged rabbit bot fly, Cuterebra buccata

Figure 3. Newly emerged C. buccata with shed puparium



The image in Figure 1 represents well the type of photographic opportunity that I look for because it readily leads into various side stories.  Here are some examples: 

1) Amazing natural history—you just can’t make this stuff up.  The Catts review article cited discusses numerous other aspects of bot fly natural history in addition to the discussion above.  For example:

  1. Cuterebra spp. are thought to oviposit in the host habitat where the eggs await close passage of a host.  As with the D. hominis, the body heat of the host stimulates the eggs to hatch. The first instar larvae enter the host through an existing orifice or wound and then travel through the host to find a suitable subcutaneous location to create a warble.  Here, the larva molts to the second instar and continues to draw nourishment from the host.  Cuterebra larvae feed on fluids of the host as opposed to feeding on actual tissue, which would be more damaging to the host.
  2. The larvae spend roughly one month in the host.  Upon completion of the third instar, the larva exits the host, digs into the soil, and pupates.  Bot flies overwinter as pupae.
  3. Adults do not feed and are relatively short-lived.  Their attention is focused on the serious business of reproduction. 

2) Mimicry.  As you can see from the image, C. abdominalis very much resembles a bumble bee.  This image is great for presentations because it captures the attention of grade school kids.  I include this image at the end of a series of slides containing images of bees and wasps alongside the flies that mimic them.  Kids become very engaged and have a lot of fun trying to guess which images represent the models and which represent the mimics.  By the end of the series the kids have become pretty savvy about picking out the imposters but I present this image last and C. abdominalis is so bizarre that it always stumps the audience.  The kids become even more captivated by the discussion of how bot flies make a living.

3) Insect photography technique.  It’s thrilling to find new insects, but the experience can quickly turn disappointing if the insect flies off never to be seen again just as you begin to approach it for a photograph. That would have been the case with my encounter with C. abdominalis if I didn’t have a companion with me in the field.  I was lucky to have my wife, Jess, with me on this hike.  She kept an eye on the fly as I moved in for pictures.  Once or twice it flew at my approach, and Jess was able to keep track of it so I could try again.  Ted and I have also acted as spotters for one another, and this has made the difference between getting the pic or not.

4) Great location.  We encountered C. abdominalis on the edge of the scenic glade that slopes away from the Trail House at Shaw Nature Reserve in Franklin County, Missouri.  It’s always fun to revisit certain places and get to know them and the photographic opportunities they provide.  The Nature Reserve is one such place for me.  It offers countless opportunities for insect photography close to St. Louis due to a wide variety of habitats including prairie, glade, forest, wetland, and riparian areas. 

REFERENCES:

Catts E. 1982. Biology of New World bot flies: Cuterebridae. Annual Review of Entomology 27:313–338.

Cramer J. and G. Cameron. 2006. Effects of bot fly (Cuterebra fontinella) parasitism on a population of white-footed mice (Peromyscus leucopus). Journal of Mammalogy 86:1103–1111.

Slansky, F. 2007. Insect/mammal associations: Effects of cuterebrid bot fly parasites on their hosts. Annual Review of Entomology 52:17–36.

Copyright © Christopher R. Brown 2012