The Pea Aphid Genome

Acyrthociphon pisum, the Pea Aphid

The genome sequence of the pea aphid Acyrthosiphon pisum was published today in PLoS. Concurrently, a set of supporting papers has come out in Insect Molecular Biology. This genome is significant for a number of reasons- it’s the first Hemipteran genome to be sequenced, aphids have an unusual reproductive cycle, and this particular species is a serious agricultural pest.

I’ve not had time to fully digest the paper, but it seems the salient features of this genome are:

• extensive gene duplications
• a higher gene count than most other known genomes (including our own!), perhaps related to all the duplications
• a surprising loss of immune genes

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source:  The International Aphid Genomics Consortium 2010 Genome Sequence of the Pea Aphid Acyrthosiphon pisum. PLoS Biol 8(2): e1000313. doi:10.1371/journal.pbio.1000313

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Formica integroides tending aphids

Formica integroides wood ants tending pine aphids (California, USA)

Photo details: Canon MP-E 65mm 1-5x macro lens on a Canon EOS D60.
ISO 100, f/13, 1/200 sec, twin flash diffused through tracing paper

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A Flurry of Soybean Aphids

Soybean aphids piling up in a spider web

It’s been snowing aphids the past few days here in Champaign-Urbana. Trillions of them are drifting across town, settling out on our garden, getting caught in our hair. I’ve never seen anything like it.

I recently learned that this sternorrhynchan storm is composed of soybean aphids (Aphis glycines). That would explain all the aphid biomass. Illinois is a major producer of soy, and there’s no shortage of soy fields around here. Sensing the end of summer, the aphids are moving en masse to their winter host, buckthorn.

Soy has traditionally been easy to grow in North America as it lacked any major insect pests. Until about 10 years ago, that is. That’s when the first soybean aphids, an Asian species, showed up in Wisconsin. Given the sheer numbers of these insects, I can’t imagine this bodes well for soy yields this year.

***update (9/21): I’ve added an Aphid FAQ

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The Yamazaki “Going Way Out On A Limb” Award

This morning I was picking through recent ant literature for a 2008 myrmecological retrospective post when I stumbled on this little gem.

Why do autumn leaves change to such striking colors?  Kazuo Yamazaki thinks it’s all about the ants:

Therefore, bright autumn leaves may have adaptive significance, attracting myrmecophilous specialist aphids and their attending ants and, thus, reducing herbivory and competition among aphids.

I hereby proclaim Kazuo Yamazaki the first recipient of an award in his own name, the Yamazaki “Going Way Out On A Limb” Award, for creative lateral thinking in proposing scientific hypotheses.

source: Yakazaki, K. 2008. Autumn leaf colouration: a new hypothesis involving plant-ant mutualism via aphids. Naturwissenschaften 95: 1432-1904.

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Birth of an Aphid

Macrosiphum rosae – Rose aphids
Arizona

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Why I’m glad I’m not an insect (part 2)

I can’t imagine a more unpleasant way to go. This poor oleander aphid (Aphis nerii) has its innards sucked out by a hoverfly larva.

photo details: Canon MP-E 65mm 1-5x macro lens on a Canon 20D
f/13, 1/250 sec, ISO 100
MT-24EX flash diffused through tracing paper
levels adjusted in Photoshop.

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One of these Things is Not Like the Others

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