Bollworms rising!

One of the most pernicious pests that U.S. farmers have battled is the larval stage of Helicoverpa zea (Lepidoptera: Noctuidae). This insect is destructive enough to have earned not just one official common name, but four (corn earworm, cotton bollworm, soybean podworm, and tomato fruitworm)—one for each of the crops in which it has attained major pest status. It isn’t only North American farmers, however, that must deal with this pest, but South American farmers as well. For many decades, corn and cotton have been its most important hosts in North America, but in recent years its importance has increased steadily in soybean as well, particularly across the mid-south. In South America, however, it seems satisfied—curiously—to confine its attacks to corn. Lest you think that South American farmers are getting off easy, there are other species of Helicoverpa in South America that are causing problems of their own. Perhaps the most troubling one is H. armigera, the Old World bollworm¹—a sister species to H. zea (Goldsmith & Marec 2010) native to Africa, Asia, and Australia and just as polyphagous as H. zea that was recently found infesting corn, cotton, soybean, and other crops in several areas of Brazil.

¹ Interestingly, in the Old World this species is called the “American bollworm,” despite the fact that it did not come from the Americas at all. I guess neither hemisphere wants to take the blame for this species.

Helicoverpa gelotopeon (South American bollworm) | Buenos Aires Province, Argentina

Helicoverpa gelotopeon (South American bollworm) | Buenos Aires Province, Argentina

While we wait to see what impact H. armigera ends up having in South America, another species of the genus is quietly rising from the ranks of secondary to primary pest further south on the continent. For many years, Helicoverpa gelotopeon (or South American bollworm) has been a sometimes pest of cotton and other crops in Argentina, Chile and Uruguay (Evangelina et al. 2012), but in a situation that mirrors the rise of H. zea on soybean in North America, the incidence of H. gelotopeon has grown during the past few years in the more southern soybean growing areas of South America as well. Like its North American counterpart, this insect causes not only indirect damage by feeding on the foliage of the plant during vegetative stages of growth (reducing photosynthetic capacity of the plant), but also direct damage by feeding on the developing pods during reproductive stages of growth. Predictably (and regrettably), farmers have responded by increasing applications of organophosphate insecticides, but the efficacy of these products—despite their relatively high toxicity—has often been inadequate to prevent yield losses. As a result, other management techniques and technologies will be required to keep this insect from having a major impact on soybean production in the temperate regions of Argentina.

Young larvae feed on foliage (note the very small caterpillar in the lower center area of the leaf).

Young larvae feed on foliage (note the very small caterpillar in lower left area of the leaf).

A mid-instar larvae feeding on soybean foliage.

A mid-instar larvae feeds on soybean foliage and exhibits the black pinacula characteristic of the subfamily.

Larger larvae feed on developing pods, breaching the wall of the pod to consume the seeds within.

Larger larvae feed on developing pods, breaching the wall of the pod to consume the seeds within.

Adults are slightly smaller than H. zea and a little darker with somewhat bolder markings.

The photographs in this post may well be the best—and perhaps even the only ones—available of this species. A Google image search turned up nothing, and have I been unable to find any literature with photographs of either the adults or the larvae and their damage. If you are aware of any please leave a comment with the citation.


Goldsmith, M. R. & Marec, F. 2010. Molecular Biology and Genetics of the Lepidoptera. CRC Press, Boca Raton, Florida, 368 pp.

Evangelina, P., F. Crepo & J. C. Gamundi. 2012. Evaluación del daño simulado de “oruga bolillera” Helicoverpa gelotopoeon (Dyar) en estados vegetativos del cultivo de soja. Unpublished report, Instituto Nacional de Tecnología Agropecuaria (INTA), 6 pp.

Copyright © Ted C. MacRae 2013

The true Ombú

Recall ID Challenge #21, which featured a photograph of the massively buttressed trunk of a rubber tree (Ficus elastica) planted more than 200 years ago in Buenos Aires, Argentina and give the name Gran Gomero (meaning “big rubber”). There are many photographs of this tree on the internet, owing to its celebrity status, which allowed more than a few participants to properly guess its identity. Unfortunately, one participant still guessed the wrong answer despite having found an image of the exact same tree due to the tree being incorrectly identified as an Ombú tree (Phytolacca dioica). Unlike the rubber tree, which is native to south and southeast Asia, the Ombú is indigenous to South America and is, in fact, the only “tree” that occurs naturally in the South American Pampas. I place the word tree in parentheses, because this plant—also unlike the rubber tree—is not even really a tree, but rather multi-stemmed shrub (albeit a very large one) in the family Phytolaccaceae (relative of the common pokeweed). Like its North American cousin, the milky sap is laced with toxic compounds that protect it from vertebrate and invertebrate herbivores, and its massive, fire resistant trunks consist of soft water storage tissues arising from enlarged bases. These features are obvious adaptations to life on the Pampas, where rainfall is scarce (10–30 in per year) and fires are frequent.

Ombú (Phytolacca dioica) | Buenos Aires, Argentina

Ombú (Phytolacca dioica) | Buenos Aires, Argentina

While not nearly as spectacular as El Gran Gomero, there is an Ombú growing nearby in the same very plaza adjacent to the Recoleta Cemetery (above photo) that typifies the multi-stemmed, swollen-base appearance that very large specimens assume. It is easy to see how, at least based on superficial appearance, one could mistake El Gran Gomero for an Ombú; however, it also goes to show that one should always be cautious about too quickly accepting what they find on the internet (watch somebody now point out an error in this post!).

Here is another (better) photo of the exact same tree.

Copyright © Ted C. MacRae 2013

The 213-year old “Gran Gomero”

Here are two more views of the tree featured in ID Challenge #21. This is El “Gran Gomero,” a planted rubber tree (Ficus elastica) located in the upscale Recoleta district of Buenos Aires, Argentina. Whenever locals give a name to an individual tree, you know it has to be something special, and this tree certainly does not disappoint. Huge, buttress roots and massive branches supporting a majestic, 50-meter wide crown make it an impressive sight indeed. Its branches are so large that wooden supports have been placed beneath them to help support their great weight and prevent them from breaking.

El "Gran Gomero" rubber tree (Ficus elasticus) | Buenos Aires, Argentina

El “Gran Gomero” rubber tree (Ficus elasticus) | Buenos Aires, Argentina

There seems to be some question about how old this tree actually is. A Wikipedia entry on the Recoleta district mentions that the tree was planted in 1791 by Martín José Altolaguirre, a landowner in the area at the time, making it a cool 222 years old! Wikimapia claims that the tree was planted in 1826 by Martín de Altolaguirre in the adjacent Recoleta Cemetary (itself worth a blog post) and transplanted to its current location eight years later. Still other sources, such as Buenos Aires Delivery and numerous individual blog posts state that the tree was planted in 1870 by the monks of the Recoleta. Finally, there is a sign at the base of the tree that says the tree was planted in 1800, again by the monks of the Recoleta, and that the fence was donated to the city by the nearby cafe La Biela. Unfortnately, I did not photograph the sign, but I did find a photo of it on Flickr. Perhaps the 9-year difference in planting date between the sign and Wikipedia has to do with the transplanting from its original location in the cemetary as mentioned by Wikimapia. Regardless of its true age, El Gran Gomero must certainly be among the oldest of any residing in a city as large as Buenos Aires.


Huge buttress roots support a massive, 50-meter wide crown.

Huge buttress roots support a massive, 50-meter wide crown.

Just when I was beginning to think nobody read this blog anymore, a record 30 people participated in this ID Challenge. Even more impressive is that more than a few got it right! Timing is everything, however, and 3-time BitB Challenge Champion Ben Coulter takes the win due to his speedy response and early-bird bonuses that netted him a total of 23 points. Also making the podium were Chelydra and Brady Richards with 18 each. The overall leader is now Ben Coulter with 33 points. Bill Rockenbeck and Chelydra both follow with 21 points, but in the event of a tie-breaker Bill would get the nod by virtue of having participated in more challenges. Look for another installment of BitB Challenge Session #7 in the near future.

Copyright © Ted C. MacRae 2013

ID Challenge #21

Time for another installment of BitB Challenge Session #7. This one is going to be a bit different from previous versions—can you identify the tree in the photo? Not the scientific name, not the common name, but the actual name of this particular tree. Include its location and any cultural significance it may have (both historical and current) and you’ll be well on your way towards winning this challenge. Points structure will be decided after I see what kind of response I get (this is also a test to see if anyone still reads this blog).

Good luck!


Copyright © Ted. C. MacRae 2013

These bugs rock!

These stones were given to me recently by a local insect enthusiast who is an admitted collector of all things natural history. According to him, the stones were among numerous items that he was allowed to “salvage” many decades earlier from the home of a similarly inclined individual from the previous generation. He has stored these and other items in his home ever since but now finds himself in the mood to distribute the items he has spent a lifetime collecting. Beyond this, I know nothing of the provenance of these stones or even if they represent something truly artifactual versus just the classroom efforts of a more contemporary school child. I’ll welcome any opinions that may be had, but even if none are received these stones will nicely decorate some little corner of my “museum”—hopefully for decades to come.




Copyright © Ted C. MacRae

The “little soybean weevil”

Lepidopteran caterpillars are without question the most important pests affecting soybean in South America, while stink bugs run a close second in terms of economic impact and as the targets of insecticide applications. There are, however, a number of weevil species (order Coleoptera, family Curculionidae) whose incidence has increased during the past decade or so as the area planted to soybean continues its decade’s long expansion on the continent. The most important of these is Sternechus subsignatus, a  relatively large (and rather attractive black-and-yellow) species that was first detected in southern Brazil in the 1970s. It has since spread to northern Brazil and in recent years has also begun affecting soybean in Salta and Tucumán Provinces of northern Argentina (sometimes considered a distinct species, S. pinguis). Known locally as “picudo grande” (big weevil), adults clip the petiole of leaves and girdle the stems, leading to stand loss. One adult is capable of killing multiple plants, so that even light infestations can result in severe damage.


Promecops carinicollis | Tucumán Province, Argentina

I’ve not yet seen “big weevils” for myself, but there are at least two other species that are showing up in soybean fields, particularly in Salta and Tucumán Provinces. During my recent visit to Argentina I happened upon a soybean field in northern Tucumán infested with one of them, Promecops carinicollis, a few photos of which I show here. This species is much smaller than S. subsignatus and is, thus, called “picudo chico” (little weevil)—certainly an appropriate name for the 3- to 4-mm long adults. While the integument is black, the body is densely covered with flat scales that form irregular white blotches on the elytra and otherwise give the beetle a mottled-brown appearance.


Damage consists of adult feeding around the leaflet margins, giving them a scalloped appearance.

Like S. subsignatus, it is the adults that cause damage to the plants, although instead of the stems and petioles their feeding seems to be confined to the margins of the leaflets. This gives the leaflets a “scalloped edge” appearance that is quite distinctive and unlike the leaf damage caused by other leaf-feeding insects of soybean. The feeding causes a general reduction of the leaf surface area of the plant, which reduces the plant’s capacity to photosynthesize. However, as soybean has a rather high capacity to compensate for foliage loss by growing new foliage, especially during the earlier vegetative stages of growth, it would take rather high pressure by these weevils to cause enough damage to result in yield loss. It may be one of those soybean pests for which insecticide applications are made much more often than is warranted. The most important impact of this insect probably occurs just after seedling emergence, during which time feeding on the cotyledons and first leaves can weaken seedlings enough to cause stand loss.

Promecops carinicollis | Tucumán Province, Argentina

Beginning the process of making more Promecops carinicollis.

Copyright © Ted C. MacRae 2013

Fun at Salinas Grandes

My colleagues and I greatly enjoyed our visit to the Salinas Grandes salt flats in Catamarca Province, but there was a moment of tension between Federico and Agustín. You see, Federico is only 12″ tall, so we have to keep a close eye on him to make sure he doesn’t get himself into any trouble. Apparently he had wandered off too far for Agustín’s comfort, leading to a bit of a scolding. Despite his small size, however, Federico took it all in stride and stayed close for the remainder of our visit.

Copyright © Ted C. MacRae 2013