Pivotal Pervasive Pigments: Carotenoids in insect ecology

Carotenoids are nearly ubiquitous organic compounds involved in all sorts of important

Diverse carrots colored by carotenoids

Diverse carrots colored by carotenoids

functions across all major groups of organisms. They play key roles in photosynthesis in plants, they function as antioxidants, and they provide many of the bright yellow, orange, and red coloring we see in plants, fungi, and animals. For example, the familiar orange coloration of carrots and red coloration of tomatoes is derived from carotenoids.

In a newly published paper in the journal Arthropod-Plant Interactions, Jeremy Heath (former PhD student), reviews the many varied functions of carotenoids in insects, with emphasis in how carotenoids and their derivatives influence interactions between insect and their environments (notably plants).

A stylized, schematic representation of the various known and hypothesized functions of carotenoids in insects that mediate ecological interactions.

A stylized, schematic representation of the various known and hypothesized functions of carotenoids in insects that mediate ecological interactions.

He briefly reviews the structure and biosynthesis of these molecules and then discusses their roles in cryptic and aposematic coloration in insects, their importance in vision, photoperiodism and diapause, their function as antioxidants, and their role in signaling. He also explores the possible functions of carotenoid derivatives such as strigolactones and volatile apocarotenoids in mediating interactions between insects and plants (and fungi), and between insects and their parasitoid enemies. Contact Jeremy (heath.22@wright.edu) or myself (john.stireman@wright.edu) for reprints.

Heath, J.J., D. Cipollini, and J.O. Stireman III. 2013. The role of carotenoids and their derivatives in mediating interactions between insects and their environment. Arthropod-Plant Interactions 7:1-20.

Posted in Scientific publications | Tagged , , | Leave a comment

Ecuador Expedition 2012

I (Stireman) recently returned from a trip to Ecuador. The primary reasons for the trip were 1. To collect tachinid flies for systematic and biodiversity research, and 2. To get graduate student, Karen Pedersen, set up for her studies on the multitrophic determinants of host specificity in Altinote butterflies (Nymphalidae: Acraeinae). There was also the added benefit of meeting up with some of my old grad school buddies, Harold Greeney (Tropical Ornithologist and Entomologist), Caleb Gordon (bird fanatic), Matt Kaplan (high through-put moleculoid master and lizard man), and Margy Green (Optics engineer and herp/bug photographer) and several of their biophile colleagues.

This was my favorite trip to Ecuador thus far (and I’ve been there a few times). We explored a wide diversity of habitat types and were able to travel to some magnificent areas. We started out at Yanayacu Biological Station, epicenter of my research program in

The view form Yanayacu

The view from Yanayacu

Ecuador, in montane cloud forest on the East slope of the Andes (~2000 m). This the best place to find tachinids that I have ever seen. They are everywhere, in an amazing variety of forms. They are thick as, well…flies. You hardly have to try to look for them. My pet hypothesis for their amazing abundance and diversity here is a combination of the almost infinite opportunities for habitat specialization and semi-isolation provided by the Andes, the ridiculous diversity of potential hosts, and the relative lack of ants. Perhaps I will elaborate sometime…

From Yanayacu, we travelled to the high paramo, reaching elevations as high as 4300 meters (Like 14400 ft). It is remarkable habitat of cushion plants and club mosses, but it’s awful chilly when the sun isn’t out (as it was not when we went…which explains the poor showing of tachinids).

Paramo near Papallacta

Paramo near Papallacta

From there some of us split off to visit a small reserve called Jatun Sacha. This is a lowland reserve at about 450 m with nice accommodations and some attractive old growth forest

A tree frog at Jatun Sacha (see, I like vertebrates too)

A tree frog at Jatun Sacha (see, I like vertebrates too)

(It’s also easy to get to). The group rejoined to visit another small reserve in the Andean foothills called Bigal River Biological Reserve that adjoins the huge Sumaco National Park. This reserve, operated by a French couple (Marion and Thierry, who cooked us super-delicious food) required a little bit of walking on a treacherously muddy old logging road to get to (luckily with donkeys packing in most of our gear). Though this is a fairly new reserve, the forest is old, diverse, and

Lycaenid at El Bigal

Lycaenid at El Bigal

relatively untouched. I spent most of my time walking along the road (good place for flies) and peeing on select plants to attract a diversity of flies, stingless bees, and butterflies. I cannot overstate the utility of urine as a tachinid (and other fly) attractant in the wet, salt poor lowland forest. I even saved jars of pee for this express purpose.

Finally, we traveled to the heart of the Ecuadorian Amazon to a fantastic lodge called Shiripuno, located on the Huaorani (native peoples)  Reserve and not far from the “intangible zone”, where there are people living that have no, and want no, contact with western civilization. Being in this place, it is easy to forget that there is any threat to the lowland rainforest; the forest seems endless, there are parrots and toucans everywhere,

boating down the Shiripuno

boating down the Shiripuno

there are 10 species of monkeys, and the insect diversity is amazing. The naturalist Fernando (Vaca), as well as several Huaorani guides, led us on a number of eventful outings on the river and on trails, but we were also free to explore the trails on our own. I spent a lot of time in around the edges of the main clearing of the lodge, monitoring my pee and sugar-water trapline for flies – and even this was awesome.

I should note that my good friend and scientific collaborator Harold Greeney arranged all these trips, and I am very thankful he did. I should also note that my tachinid collecting was conducted under the auspices of two major research programs the Stireman lab is involved with: A long term biotic survey and inventory of caterpillar-plant-parasitoid interactions in Ecuador (led by Lee Dyer at U. Nevada) and the World Phylogeny of Tachinidae project led by our lab (see previous post). I was able to collect quite a diversity of taxa (many of which will be deposited in the Museo Nacional del Ecuador in Quito) that will be extremely useful for our ongoing investigations of tachinid  ecology, diversity, and phylogeny. By the way, I left Karen (my student) down there at Yanayacu for four months to work on her studies of plant-butterfly-parasitoid interactions. I’m a little jealous.

Endless forest seen from the Mirador trail at Shiripuno

“Endless” forest seen from the Mirador trail at Shiripuno

One of the few tachinid shots I took (probably a blondeliine. Phyllophilopsis??)

One of the few tachinid shots I took (probably a blondeliine. Phyllophilopsis??)

Mesembrinella (Calliphoridae sensu lato) on rotting banana

Mesembrinella (Calliphoridae sensu lato) on rotting banana

Posted in Meetings & Travel | Leave a comment

Doctor Heath and Master Davis

Congratulations to Environmental Science PhD student Jeremy Heath for successfully defending his thesis this week!! Jeremy’s thesis, “Assessing the drivers of adaptive radiation in a complex of gall midges: A multitrophic perspective on ecological speciation,” took about a ream of paper to print out, and that was leaving out a lot of data and experiments that did not make the cut. Three of the chapters are already published or in press (see previous post), and I believe the two final chapters will be his biggest papers yet! Go Jeremy!

The day after Jeremy’s successful defense, Masters student Dan Davis defended his thesis research on “The phylogenetic relationships of Tachinidae (Insecta:Diptera) with a focus on subfamily structure.” This work is a big reason why our proposal to analyze the phylogeny of World Tachinidae got funded. Dan did a bang-up job with both the written and oral components. His presentation was especially well delivered (and he looked pretty damn sharp with that tie and sport jacket). Congratulations Dan!!

Posted in Uncategorized | Leave a comment

Phylogeny of the Tachinidae World Tour, Part 1: South Africa

One of the major pursuits in the Stireman lab right now is to assemble and analyze a phylogeny of Tachinidae of the world. If you know what tachinid flies are (i.e., awesomely diverse parasitoid flies, again I refer you to Jim O’Hara’s great tachinid pages), then you probably know that it is a difficult group to understand and identify. The family is enormous, with nearly 10,000 described species, and there is great morphological homogeneity in some groups, incredible diversity in others, and rampant homoplasy (convergences and reversals) throughout. In short, it is a group in sore need of broad-scale phylogenetic analysis and reassessment of classification. I, along with collaborators Jim O’Hara (CNC), Kevin Moulton (U. Tenn.), Pierfilippo Cerretti (U. Roma), Isaac Winkler (WSU), are setting out to do just that with the help of the larger global tachinidology community.

Cylindromyia sp., a widespread genus of wasp-like tachinids. These were found resting on roads or in washes, acting very much like wasps.

As part of our goal of reconstructing a framework phylogeny of world Tachinidae, Jim, Isaac, Pierfilippo and I traveled to South Africa in October to try to collect key and endemic taxa from the western cape region. We met acalyptrate specialist Ashley Kirk-Spriggs (S.A. National Museum, Bloemfontein) in Capetown, rented a truck, and drove all around the western cape looking for tachinids. I say “looking for”, rather than “collecting” because it was some of the most difficult tachinid collecting I have experienced. The only person that seemed to have much luck (though I doubt it was luck) was Pierfilippo, who always caught the first and most tachinids at any site we stopped at. We were  lucky to have the privilege of Ashley’s company, not only because of the delicious Braai he cooked for us regularly, but also because of the big Malaise traps he brought that allowed us to collect many taxa we would not have otherwise gotten. Despite the difficult collecting, we did collect several hundred specimens including many important taxa, so the trip was a success. Perhaps our best find was several specimens of the odd tachinid Rondanioestrus apivorus, a parasitoid of adult honeybees!

View from Table Mountain National Park

I don’t have time (nor inclination) to go into a full travelogue right now. Suffice it to say that the Western Cape landscape is incredibly beautiful and its flora and fauna fascinating. Enjoy the associated photos.

Beautiful flowers (mostly Mesembryanthemaceae and Asteraceae) in Anysberg Nature Reserve (but we saw virtually no tachinids or much of anything aside from bees visiting them)

An example of the plentiful and diverse Mesemb flora

The view outside our cabin in the Gamkaskloof Nature reserve, also known as “Die Hel”. Probably our best site for tachinids and rhinophorids.

We were a bit late in the season for Proteas – but this was a nice one

A rocky slope in Anysberg with interesting plants. We did find some tachinids in this area (e.g., Pseudodinera) on our way to a hill top.

Rhinophorids (a family of isopod parasitoid, closely related to tachinids) were plentiful, although not very diverse. This one, photographed by Isaac, is missing legs we took for DNA.

Rhinophorids generally have a weakly developed subscutellum, unlike the well-developed subscutellum found in nearly all tachinids.

Posted in Meetings & Travel | Tagged , , | 1 Comment

Carnivores and carotenoids…a new paper by Jeremy Heath

PhD student Jeremy Heath had something additional to be thankful for this Thanksgiving. His manuscript entitled “Carnivores and carotenoids are associated with adaptive  behavioural divergence in a radiation of gall midges” was just officially published (online) in the journal Ecological Entomology. In this paper, Jeremy and coauthors explore adaptive phenotypic divergence in populations of the galling midge Asteromyia carbonifera that coexist on the same host plant, the goldenrod Solidago altissima. He goes beyond analyses of gall morphology (which has been explored in previous papers), to examine variation in “ovipositional phenotype” (essentially where they midges deposit their eggs) and carotenoid constituents of  salivary and accessory glands (orange-colored chemicals important in all sorts of biological processes), and how this may influence interactions with both host plants and parasitoid enemies (I won’t give it all away, read the paper!). It is a dense paper, chock full of experiments, tantalizing results, and interesting possibilities. I invite you to take a look at it, there is something in there for everybody (I am sure Jeremy (heath.22@wright.edu) would be happy to send you a pdf).

Posted in Scientific publications | Tagged , , , | 1 Comment

Enemy mine

Bob Kula and colleagues (Oscar Dix-Luna and Scott Shaw) recently published a revision of the braconid genus Ilatha. These are relatively large, often brightly colored braconid wasps found exclusively in the New World tropics. They are certainly attractive wasps, but the most fascinating thing about them (to me) is that they are hyper-parasitoids of tachinid flies. That is, they are parasitoids of tachinid flies, which are themselves parasitoids of caterpillars. Apparently, adult female wasps locate caterpillars that already contain a developing tachinid and lay an egg with their piercing ovipositors through the caterpillar into the tachinid larva. The juvenile braconid then bides its time while the tachinid proceeds to devour the caterpillar (from the inside). Eventually, the tachinid kills the host and emerges to pupate, at which time the braconid proceeds to devour the tachinid (from the inside). It’s like those Russian dolls. Totally cool (except that they are eating my beloved tachinid flies!)

Some of the specimens that Kula et al. used in their species descriptions were reared as part of our collaborative NSF Biological Surveys and Inventories project focused on Caterpillars and Parasitoids of the Eastern Andes(on which Scott Shaw is a Principal Investigator). For attempting to identify some of the tachinid hosts of Ilatha from puparia, the authors honored me by naming one species (right) Ilatha stiremani. I am truly honored to have such an interesting and beautiful (at least in my eyes) wasp bear my name – even if it is a mortal enemy of my tachinid brethren. Thanks Guys!

Posted in insects etc. | Tagged , | Leave a comment

Beth Stayrook receives award

Beth Stayrook, undergraduate research assistant extraordinare in the Stireman lab, was recently awarded a $1500 scholarship award from the Women in Science Giving Circle at Wright State University. Beth is a seriously smart, dual major in Biology and Chemistry. Way to go Beth! You Rock!

Posted in Awards | Tagged , | 1 Comment

Tachinid flies and the final frontier…

Forest canopies are often referred to as one of the “final frontiers” of biodiversity exploration. We know astonishingly little about what organisms and ecological interactions occur in forest canopies, primarily due to the difficulty in sampling and studying them. In recent years there have been many initiatives to begin exploring the flora and fauna of forest canopies, particularly in the tropics. These efforts have revealed diverse communities inhabiting the upper reaches of tree canopies, often quite distinct from those occurring near ground-level in the same areas.

In a recently published study in the journal Insect Conservation and Diversity led by Pierfilippo Cerretti (Univ. Roma), we analyzed the diversity and composition of tachinid flies in the canopy and understory of a temperate forest in Italy (Bosco Fontana, right). Using 14 Malaise traps (7 suspended), we found that the canopy hosted a distinct community of tachinid flies.

Overall, more tachinids (were collected from understory traps (36) than from canopy traps (28), but the canopy traps had higher evenness and high diversity values. A number of species occurred solely or primarily in just one of the habitats and many of those that occurred in both habitats showed strong sex biases in one habitat or the other. This is one of the very few studies that have ever examined a canopy parasitoid communities, and the only rigorous quantitative study examining vertical stratification of forest tachinids. We hope to pursue more such studies of tachinid and other insect communities in this “last” frontier.

Stireman, J.O. III, Cerretti, P., Whitmore, D., Hardersen, S. and Gianelle, D. 2012. Composition and stratification of a tachinid (Diptera: Tachinidae) parasitoid community in a European temperate plain forest. Insect Conservation and Diversity 5:346-357.
Posted in Scientific publications | Tagged , , | Leave a comment

Paper on adaptive radiation in gall midges published in Journal of Evolutionary Biology

Stireman, collaborator Patrick Abbot, and Lab technician Hilary Devlin have just published a paper analyzing the extraordinary radiation of Asteromyia carbonifera gall midges on their Solidago hosts across North America. We show that this nominal species is actually comprised of a multitude of distinct evolutionary lineages that differ in host plant use and gall morphology. However, there is very little genetic structure related to geography.

These results suggest that A. carbonifera has undergone a very recent, rapid adaptive radiation, driven by ecological selective pressure from both lower trophic levels (host plant suitability and defenses) and higher ones (parasitoids, which select on gall morphology). Interestingly, divergence in gall morphology and host-plant associations appear to evolve relatively rapidly, with similar gall forms evolving multiple times, and host plants being repeatedly colonized by different lineages.

This is a fascinating example of very recent, even current, adaptive radiation in which we can still perceive the selective forces driving phenotypic divergence. However, this paper primarily focuses on patterns observed in the genetic structure of populations, and much more needs to be done confirming the processes responsible.

Please e-mail Stireman (john.stireman@wright.edu) if you would like a pdf of this paper
Posted in Uncategorized | Leave a comment

Stireman attends the International Congress of Entomology in South Korea

For a first real report from the Stireman lab, I thought I might say a few words about my recent trip to South Korea to attend the XXIV International Congress of Entomology. This meeting, my first ICE actually, was held at the EXCO convention center in the city of Daegu, which is located in Southwest S. Korea. I cannot begin to describe the diversity of interesting talks and posters. There were many concurrent sessions covering everything from genomics to biogeography. A few of the general oral sessions were eclectic assemblages such as, my favorite title, “Ecology: Genetics, pollution, symbionts & prey-predator interaction.”

I spoke about our recently funded NSF proposal to study the phylogeny and evolution of tachinid flies in a symposium on the evolution and phylogeny of Diptera (flies) organized by Brian Wiegmann and David Yeates (thanks guys!). Of course, tachinids are awesome, diverse, and understudied parasitoids that are the focus of much work in the lab. At some point, I should write about them here, but for now, you can check out Jim O’Hara’s great introduction. As we are just getting underway on this project (with collaborators Jim O’Hara, Pierfilippo Cerretti, Kevin Moulton, and Isaac Winkler), my talk was a little light on results, but I hope I convinced the audience that tachinids are a group that sorely needs modern systematic work and that there are many interesting evolutionary questions that we can explore with them.

This was my first trip to any Asian country, so of course I found it very interesting; the language, the food, the culture, all pretty novel. The Korean people were very friendly and helpful, which is good, because even after spending over a week there, I was still working on “hello” (안녕하세요, annyeonghaseyo) and “Thank you” (감사합니다, kamsahamnida).

Although there were many great talks, the highlight of the meeting for me was a brief trip up to Palgongsan Natural Park where we walked through the forest up to a giant stone Buddha and saw amazing temples. Although it was mostly rainy, The fog covered peaks and echoing buddhist chanting lent the experience a mystical quality (and there were tachinids too!).

Buddhist temple in Palgongsan area

Korean limacodid with tachinid eggs!

Posted in Meetings & Travel | Tagged | Leave a comment