Mini-review of the “other” parasitoids

fig1Stireman (me) was recently invited to write a mini-review of the community ecology of non-hymenopteran parasitoids for the journal Current Opinion in Insect Science. This was a difficult task as the review was supposed to focus on recent (last 5 years) literature, and was severely constrained in length and number of references. Still, I hope that it provides a decent overview of some of the recent research on the topic (focusing on dipteran parasitoids) and helps to spur further research.

The full text can be accessed here at the publisher’s web site (at least for a while). Enjoy!

 

 

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Ph.D. student opportunity: ecology, evolution, and systematics of tachinid flies

I am currently seunknownParerigoniiniAUS064eking a Ph.D. student to join my laboratory studying the evolution and ecology of parasitoid flies. While the specific focus of the dissertation research is negotiable, the research assistantship will require contributing to a collaborative, NSF/Brazil(FAPESP) funded Dimensions of Biodiversity project focused on “Chemically mediated multi-trophic interaction diversity across tropical gradients.” My laboratory’s role in this international collaborative project is primarily focused on tachinid parasitoids. This includes identifying and documenting species, studying how they influence and are influenced by hosts and their host-plants, analyzing population- and phylo-genetic/genomic patterns and processes, and revisionary taxonomy and species description. Students will also have the opportunity to contribute to other aspects of this large and multi-disciplinary project . The successful applicant will develop a thesis research project on tachinid ecology, evolution and/or systematics employing ecological, phylogenomic, taxonomic, and comparative methods. The student will also have the opportunity to visit and participate in field research in Brazil as well as other Latin American Countries. Latin American students are particularly encouraged to apply. Click here for more information.

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Master Karen Pedersen

Congratulations are in order! WSU master’s student Karen Pedersen has successfully defended her thesis research on: LIMITATIONS OF HOST PLANT USE IN TWO ANDEAN ALTINOTE (NYMPHALIDAE, HELICONIINAE, ACRAEINI), BUTTERFLIES, FROM A TRITROPHIC PERSPECTIVE. In this research project, Karen tried to assess the determinants of host plant use in two co-occurring species of Altinote butterflies in Ecuador. Her research took place at Yanayacu Biological Station, and is an extension of our work there on plant-caterpillar-parasitoid interactions. Karen produced several short videos focused on her study system system that you can check out:

Catching Butterflies in Ecuador!!!

Egg to Adult in two Altinote butterflies

hyperparasitoid wasp easily overcomes caterpillar defenses

Finding a Host-Plant

Dysschema sp? caterpillar dances

 

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Ghosts of the cloud forest – 11 new species of Erythromelana (Tachinidae)

Although MS student Diego Inclan successfully defended his thesis more than two years ago, the focus of his research was published this year:

Inclan, D.J. & Stireman, J. O. III. 2013. Revision of the genus Erythromelana Townsend, 1918 (Diptera: Tachinidae) with description of 11 new species and analysis of their phylogeny and diversification. Zootaxa. 3621:1-82.(Abstract here)

In this lengthy manuscript Diego describes 11 new species (as you can tell from the title) of a little known, small bodied and somewhat gracile genus of tachinids in the tribe Blondeliini that occur in the Neotropical region (Northern Argentina

to Southern Mexico). Most of the species are found in cloud forest habitats in the Andes.  Diego also examines their phylogenetic relationships using morphological and molecular approaches and examines potential modes of diversification for the genus. With only three previously described species, Diego has more than quadrupled the number of known species in the genus.

Why focus on this group of small, poorly known cloud forest tachinids?

First,  exploring, documenting and describing all of Earth’s organisms is a worthy goal in itself. Each has many fascinating biological “stories” or “lessons” to tell with its unique evolutionary history and ecological niche.  Describing these species is a first step towards elucidating these lessons, which may be far reaching (e.g., I always like to point out the vast scientific knowledge we have gleaned from studying the small and nondescript species Drosophila melanogaster).

Erythromelana cryptica Inclan, one of the new species described in this study

Erythromelana cryptica Inclan, one of the new species described in this study

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A species of the diverse geometrid genus Eois, hosts of Erythromelana

However, there is another reason that we focused on this genus. It just so happens that Erythromelana species are parasitoids of small geometrids in the genus Eois. We know this because we reared several species (first known rearings for the genus) from Eois in the cloud forests of Ecuador (see post Ecuador Expedition). Eois is a very diverse genus of geometrids that feed on plants in the hyper-diverse genus Piper (Piperaceae), and this tritrophic system of plants, herbivores, and parasitoids has been the subject of a number of studies by collaborators of our “Caterpillars and Parasitoids of the Eastern Andes” biological survey project (e.g., see Wilsonetal2011). One goal of Diego’s paper was to see if Erythromelana exhibited evidence of co-evolution and host-associated differentiation with their Eois hosts. Although the degree of specificity of Erythromelana species is difficult to evaluate due to the many undescribed and cryptic species of Eois that we know of, our rearing records suggest considerable overlap in host use among these tachinids.  Thus, it would appear that perhaps geographic isolation may play a greater role in Erythromelana diversification than host associations.

Why ‘ghosts of the cloud forest’? This somewhat dramatic title refers to the rarity of Erythromelana species. Total parasitism of Eois (from over 5000 rearings) is less than 0.5% and we only recovered a single specimen from a pan trapping effort at Yanayacu that collected over 2000 other tachinids. Several of the described species are known from just a handful of specimens. Still, these ‘ghosts’ can be observed, if one knows where to look. On a few occasions they have been seen, flitting about sunlit leaves over small streams in deep cloud forests of Costa Rica and Ecuador.

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Yard insects

Just a few recent photos from my yard (click for larger images)

BlueDashersm

The Blue Dasher (Pachydiplax longipennis: Libellulidae)

Gymnosomasp.

Gymnosoma sp. (Tachinidae)

a bee fly (Bombyliidae: Phthirinae)

a bee fly (Bombyliidae: Phthirinae)

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It’s not just what’s in the field, it’s what’s around it

I have taken a long hiatus from posting any news or other items on here (for no particularly good reason) and I thought I might try to do some catching up on news from the lab. In the next several posts I will highlight some recent publications and other events over the last half year or so.OLYMPUS DIGITAL CAMERA

First, I would like to highlight a not-so-recent publication (LetBothStire2012 – actually published in 2012) led by collaborators at UC Santa Cruz, PhD student Sara Bothwell Allen and Deborah Letourneau, her advisor. For Sara’s thesis she studied the effects of surrounding land use on parasitism levels of pests and parasitoid diversity in organic agricultural fields in California. She set out “sentinel” letourneaufigspest caterpillars, confined to their plants, for one week to examine parasitism and she set out Malaise traps for two days (twice per season) to sample parasitoid diversity. She then characterized the surrounding landscape cover using GIS. Because they got quite a few tachinids, Sara and Deborah invited me to collaborate on an analysis of how landscape variables outside the fields affected tachinid diversity and parasitism inside the fields. Interestingly we found effects of many landscape variables on the tachinid fly com

munities in the agricultural fields, but the strongest pattern was an increase in tachinid abundance and diversity with increasing coverage of semi-wild perennial vegetation in the landscape (see graphs below). These results argue for that current trends towards agricultural intensification -plowing fence line to fence line are counterproductive.  Semi-wild corridors and fragments can act as refugia for parasitoids, which may reduce the need for pest control measures in organic or conventional agriculture.

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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.

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