Monday, June 9, 2008

Phids!

I have a black elderberry, Sambucus nigra, in the garden. It’s a plant widespread in Europe. A visitor from Denmark asked, “Why did you plant that? It’s a weed.“

It grows like a weed, but doesn’t spread like one. It’s easily tamed by pruning. Every year as the weather warms, as it did a week or so ago before it reverted to February, and the elderberry starts shooting out in all directions, blue-grey patches form on stems.


Aphis sambuci on Sambucus nigra.

Aphids! The species is, appropriately, Aphis sambuci, the elderberry aphid, and also European as far as I can tell -- most of the literature Google provides is in European languages.

This cluster of bugs is the product of vigorous parthenogenesis; a female producing large numbers of first instar nymphs via viviparous reproduction. All are female, clones of mama. In late summer or fall eggs will be produced, some of which, lacking a single chromosome, will be male. This leads to sexual reproduction and egg-laying. In spring, the eggs hatch into females, which start reproducing parthenogenetically -- a successful lifestyle, but perhaps, ultimately, unfulfilling?

Upon hatching, the nymphs puncture the stem of the elderberry with their stylet-like mouthpart, piercing the phloem, which carry the sugary products of photosynthesis downward. The aphids don’t even have to suck; the pressurized phloem fluid flows on in. No wonder feeding aphids look as if they might pop. What comes out of their anuses (ani?) is also sugary, and is mined by ants. There were ants on this cluster of aphids but they fell off as I was arranging the branch for a photo. Inept hymenopterans.

In a different light.

And underwater.
Kidding, blue mussels on a pier.

6 comments:

Bird said...

I got my fascination with the weird and creepy side of the natural world from watching a plain old green aphid popping out a series of replicas when I was about eight years old. It seemed to me that the offspring were only slightly smaller than their mother, which gave me a sense of exhilarated revulsion I never quite got over. Thank you for bringing back that feeling!

Daphne said...

The mussels gave me a good laugh. I actually kill a lot of bugs by drowning. I hate squishing things.

Hugh said...

Bird, You're welcome. There is nothing quite like exhilarated revulsion.

chey said...

Ah yes, that was funny, going from aphids to mussels under water.Not my favorite bug however...they love my daylilies.It's an ongoing battle.

GardenJoy4Me said...

I have had attacks on my Purpleleaf Sandcherry .. and viburnum .. so far .. I'm sure they will start snacking on something else SOON too !
You made me laugh with the mussels : )
Joy

garden girl said...

eeewwww! If it wasn't dark outside right now, I'd go check mine to make sure it's not infested.