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Leafbud gall/ parasitic fly/nematode

Fergusonina sp (gall fly) and nematode (Fergusobia brittenae sp)


These were dried and scrunched-up leaves at the ends of branches of a young eucalyptus tree. Several low branches showed a single leaf that showed this transformation. Some of the green leaves showed part of the leaf margin starting to roll over(pic #4). The leaf tissue had thickened and had a blotchy appearance. Long and cross sections of the gall show multiple locules that would have housed the gall fly larvae and associated nematode. The dried and shriveled leaf mass not brittle; it felt hard and solid.


young eucalyptus tree in a small reserve


Thanks to Martin L for identifying this as a leaf bud gall formed by a parasitic fly. Further research shows that the gall is formed by a mutualistic association between the gall fly and a nematode. It is hypothesised that the fly provides transport to the nematode to other hosts and has some nutritional benefits. Apical leafbud galls are said to be large and usually multi-locular For a fresher greener version of this, you could see martinl's brilliant spotting:

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Leuba Ridgway
Leuba Ridgway 9 years ago

Thanks Karen. I will add it to the Symbiotitc Relations mission. I thought the "other" category would be most appropriate seeing that a nematode is involved - actually a plant, arthropod and nematode ! :). However, I am happy to leave it with arthropods and thanks for moving it.

KarenL 9 years ago

Very interesting Leuba! Please consider adding this to the Symbiotic Relationships mission!
I have moved this to arthropods for you - things like galls, cocoons, nests etc. are categorized by the species that created them. The "Other" category is for worms, snails, corals & other organisms that don't fit into any of the other categories!

Mark Ridgway
Mark Ridgway 9 years ago

I wonder which one has the chemistry to make the gall or if they both contribute...

Leuba Ridgway
Leuba Ridgway 9 years ago

mutualism is one of many types of symbiosis

Mark Ridgway
Mark Ridgway 9 years ago

Ok so that's something to learn about the various forms of symbiosis.... next bit.

Mark Ridgway
Mark Ridgway 9 years ago

Trying to get my head around this...
A fly and a nematode associating for mutual purpose but not symbiotic....?
They get together they make a nice big fat gall to live inside.... ?
Evolution is absolutely amazing. Given enough time it will probably try every trick in the book.

Leuba Ridgway
Leuba Ridgway 9 years ago

Martin, thanks again for the ID. I've added some photos of a dissected gall. I found some interesting information about this - have added to notes

Leuba Ridgway
Leuba Ridgway 9 years ago

Martin, the flickr photo of the leaf gall is fantastic. So you think these might be leaf bud galls. Do you think I should have cut open one of them ? - I'll probably visit the tree again. Thanks.
I could not open your PN spotting but will try again.

MartinL 9 years ago

I found one sapling with similar fused bud leaves
They produced dipterans, like tiny fruit flies There are other things that produce leaf bud galls too.

Leuba Ridgway
Spotted by
Leuba Ridgway

Victoria, Australia

Spotted on Feb 16, 2012
Submitted on Mar 4, 2012

Spotted for Mission


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