Strange eyes, twisted wings

20 November 2013 by Christopher Buddle, posted in Insects, Natural History, Parasites

The Entomological Society of America's annual meeting last week was full of unique moments - although I highlighted a few on Segments, let me share another one with you:  After grabbing a coffee and heading to the conference centre just before I departed Austin, I had a short conversation with a PhD student from UC-Davis (Marisano James, in Jonathan Eisen's lab) studying twisted-wing parasites (the insect order Strepsiptera). More specifically, he was interested in how the male eyes of these critters work.  Their eyes are well known (among entomologists!) for being highly unusual and unique within the insects.  Don't believe me...?  Just LOOK at this photo (by Michael Hrabar a graduate student at Simon Fraser University, in British Columbia)!

Credit: Michael Hrabar. Male Strepsiptera (the retinas are visible within the eyelets)

Despite their low diversity (600 species, although still double that of the Carnivora [Bears, cats etc]), the Strepsiptera are truly amazing animals: they are obligate parasites on other arthropods, and have highly complex life cycles. For example, for species in most of the families, females don't leave their host and instead stay in a neotenic state, meaning they retain juvenile characteristics and thus lack wings, legs and eyes. Males, after emerging from their host, will fly with their odd, twisted wings, and seek out females, drawn to them by pheromones. The males are generally short-lived, thus making it somewhat unbelievable that they can find and mate with the sessile females. Larvae are mobile, and will move about to seek out new hosts. More details about their bizarre life cycles (and host-parasitoid interactions) can be found in Kathirithamby (2009), or by visiting the tree of life website. The evolutionary relationships within the Strepsiptera remain confusing and controversial. For example Pohl & Beutel (2005) state: "The relationships of the group involve one of the most troubling enigmas in insect systematics". The relationship among Strepsiptera and other insect Orders also appears controversial, as depicted from the Tree of Life Project (below; check out the question mark!). A detailed overview of these relationships can also be found on the Tree of Life site.

The talented Sean McCann, upon receiving some questions from me about Strepsiptera, has kindly let me post the following video, showing a male Xenos peckii emerging from Polistes fuscatus This is video is amazing for a lot of reasons, but what strikes me most of all is just how rapidly the male flies away after a relatively slow emergence. Pull, struggle, work-work-work and BOOM. Away he goes.

Twisted? Indeed.

Here's another photo for you, also from Sean:

Credit: Sean McCann. Polistes dorsalis, carrying a few friends

Now, imagine stopping on a street corner and discussion the biology of Strepsiptera with someone you never met before. That is a unique moment; and one of the wonderful things about scientific conferences (thanks, Entomological Society of America).

P.S. as an aside, this stunning blog post is also a must-view for those interested in this fascinating insect order.

References:


Kathirithamby J (2009). Host-parasitoid associations in Strepsiptera. Annual review of entomology, 54, 227-49 PMID: 18817508

Pohl & Beutel (2005). The phylogeny of Strepsiptera (Hexapoda) Cladistics DOI: 10.1111/j.1096-0031.2005.00074.x

ResearchBlogging.org


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