How aphids get their amino acids

[Hobjob]

I found this interesting - hope others do
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How Tiny Insects, With a Little Help, Survive on Plant Sap


By HENRY FOUNTAIN
Published: December 8, 2008

Plant sap is hardly nature’s wonder food. It is woefully lacking in essential amino acids, the kind that animals can’t synthesize on their own.
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Nicole Bengiveno/The New York Times


Symbiotic bacteria enable insect to use a nutritionally inadequate diet (The Proceedings of the Royal Society B: Biological Sciences)


It’s a good thing, then, that people don’t subsist on plant sap. But aphids do. So how do the insects get the amino acids they need?

The answer, scientists know, is that aphids have symbiotic bacteria that synthesize the amino acids for them. While there have been plenty of metabolic and other studies to show that this is true, quantitative acid-by-acid evidence of the role bacteria play has been lacking.

E. Akman Gunduz and Angela E. Douglas of the University of York in England have now provided that evidence. In a study of pea aphids reared on fava bean plants, they show that the bacteria make up for a shortfall of all of the amino acids except one. And for that, the researchers suggest, the aphid has a workaround.

The researchers analyzed the amino acid content of the plant sap, how much the aphids ingested and how much they grew. They raised other aphids on diets lacking in specific acids.

As they report in The Proceedings of the Royal Society B: Biological Sciences, the sap did not provide enough of up to seven essential amino acids (there were variations among the plants used in the experiments). But the bacteria more than made up for the disparity in all the acids except one, methionine. The researchers hypothesize that the aphid may produce methionine on its own, using an enzyme that can produce it from a related compound.

http://www.nytimes.com/2008/12/09/sc...9obaphids.html

[Meta menardi]

[quote=Hobjob;388022]It is woefully lacking in essential amino acids, the kind that animals can’t synthesize on their own.
[quote]

A very interesting thing, but it does miss one thing. Ruminants can synthesize essential amino acids, using the bacteria in the rumen. Whilst I appreciate that this not the ruminant synthesizing ,but the gut contents, this seems to be a similar process to the one described for aphids. I think the quoted statement is incorrect. Donning armour, FIRE.

[Hobjob]

I didn't know that about ruminant either - but surely the statement is correct in that that the ruminants can't do it "on their own" either.

Still that is something else learned to to-day - so no doubt someting forgotten to balance it out!

[Acutipuerilis]

Interesting! I wonder if the same applies to all Homoptera... always been curious why predatory behaviour has evolved so often among Heteroptera, but not Homoptera. This could have something to do with it, perhaps.

[poschiavanus]

Bacterial symbionts are also known for some Hets: this is from Southwood & Leston p. 47 on the Brassica Bug Eurydema oleracea (taxonomy as at 1959):

First instar larvae do not feed but take up symbiotic bacteria from the egg cement; although they can develop without these symbionts such individuals are undersized. The larvae are at times carnivorous, feeding on the eggs of other insects and upon insects themselves. However, the chief British food sources are the seeds of jack-by-the-hedge, horseradish, wild radish, and garlic
mustard, but it will take many other crucifers.

There are several other references in S&L. I leave that as an exercise for the reader (or possibly his/her computer).

[Acutipuerilis]

Hmpph - missed that! Ta for the pointer, Posch. In that case, it's still baffling me as to why there are no predatory Homoptera. It can't even be a size difference, given cicadas.