The MGS Forum
Gardening in mediterranean climates => Pests and diseases => Topic started by: MikeHardman on October 23, 2011, 09:37:00 PM
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What do we have here?
I opened this almond today and found it inside.
I would not be surprised if an exact ID was impossible. But I would be interested to know the likely suspects.
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It looks like the common nut weevil (Curculio nucum), but I thought that stuck to hazelnuts and acorns. When it does attack fruits, they do look sound externally, like your nut. I'm sure you'll find lots about it if you google it, so you may be able to exclude it then, but they grow to about a centimetre, and have brownish heads.
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Good, thanks.
I see there is an 'almond weevil' (Myllocerus laetivirens) but its larvae feed on rootlets.
And an 'almond beetle' (Mimastra cyanura) but its larvae feed on leaves.
Your nut weevil sounds promising (I note it was moved to Curculio from Balaninus, so the latter may provide further info when searching). But I, too, can find no mention of it affecting almond...
The rather good 'Pests of fruit crops: a colour handbook' By David V. Alford does not help, neither when looking at 'Curculio nucum' nor 'almond'. It is useful to have it online (and searchable) in Google Books -
http://books.google.com/books?id=wiiolhPporQC&printsec=frontcover&dq=Pests+of+fruit+crops:+a+colour+handbook+By+David+V.+Alford&hl=en&ei=wBmlTvjUDYas-gaO28mkBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CC0Q6AEwAA#v=onepage&q&f=false (http://books.google.com/books?id=wiiolhPporQC&printsec=frontcover&dq=Pests+of+fruit+crops:+a+colour+handbook+By+David+V.+Alford&hl=en&ei=wBmlTvjUDYas-gaO28mkBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CC0Q6AEwAA#v=onepage&q&f=false)
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But did your weevil larva have a brown head (if you haven't eaten it already)? If it did, and if it was about the right size, I think we can conclude that it was the culprit - especially if you were also able to spot that tell-tale 2mm bore hole in the nut wall.
I do have Alford's book and can firmly recommend it!
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Good point Alisdair. I have both halves, no pieces missing - and no hole.
Also, I did not see the head of the larva; I certainly did not see a brown one. When I looked this morning, it had gone: it and what was left of the kernel had been removed from the shell, presumably by a lizard or bird.
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Happy bird.
Unless someone (Oron, where are you?) comes up with a realistic alternative, though, I can't see what other nut-eating white grub of that shape and size could be living and feeding inside that apparently undamaged nut. It surely must be the Curculio.
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Update.
No hole per se, but there is a dark brown dot (just under 1mm in diameter) on the inside of the kernel cavity. I carefully broke the shell, showing that it penetrates as a brown cylinder a fair way towards the outside. I have no idea if it is normal or related to the larva.
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Very well done, Mike, clearly a bore hole created when soft-stage shell starting development, followed by the natural closure which ensures continued nut development with no external sign of trouble. A beautiful bit of forensic investigation, nailing the culprit!
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Well thank you Alisdair:)
If I get a chance to investigate some other almond nuts, and find a grub, I'll pay attention to its head (just to try to dot the i's and cross the t's.
Concerning grubs in sealed chambers in general, I can't help wondering how the larvae/pupae respire.