Is Alder Leaf Beetle Extending Its Food Plant Again ?

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Is Alder Leaf Beetle Extending Its Food Plant Again ?

Postby SteveMcBill on Tue Apr 22, 2014 10:35 am

Is Alder Leaf Beetle Extending Its Food Plant Again ?

Since the Alder Leaf Beetle (Agelastica alni) was re-found in Greater Manchester a few years ago (2004) it has extended its range in our area considerably, now covering most of Cheshire and Merseyside.

During that time period it has been seen to use English Alder (Alnus glutinosa) as its primary foodplant but has extended its food resources by encompassing both Grey Alder (Alnus incana) and Italian Alder (Alnus cordata). Beetles and larvae can now be found regularly on all 3 species of Alder.

However, this year (2014) I visited the area surrounding Town Park Lake in Runcorn (SJ545826) and found 10's of thousands of Alder Leaf Beetle adults on the English Alders around the lake. Then, I began to notice that the Hazel (Corylus avellana) trees round the lake also had Alder leaf beetles, in a somewhat lesser profusion, on their leaves AND the leaves displayed the same shot-hole feeding patterns as the English Alder leaves. Agelastica alni were feeding on the Hazel !!

Don, have you noticed this behaviour and if so when and where - it is the first time I have seen it. If this extension of foodplant is viable will we see another 'explosion' of Agelastica ??

Steve

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Re: Is Alder Leaf Beetle Extending Its Food Plant Again ?

Postby DonSten on Thu Apr 24, 2014 10:42 pm

Hello Steve,

Little correction required first. The species wasn't 're-found' in Greater Manchester as it had never been recorded from the area before.

As for the host food plants, although Agelastica alni tends to use Common Alder Alnus glutinosa by preference it is well known to use Alnus incana and Alnus cordata quite readily. So this isn't something it has developed recently - it was eating these from day one in the UK.

The Hazel munching is well recorded in Europe and when I did a study on the beetle I received records of the beetle on Hazel from a few people and recorded it myself from Styal Country Park and other sites. In Turkey, it is regarded as a pest by Hazelnut producers. It is also know to eat both Downy Birch Betula pubescens and Silver Birch Betula pendula - basically it is partial to plants in the Betulaceae.

Funnily enough, before I got around to answering this, I went for a run this morning along the Bridgewater canal and found A.alni on a Common Alder and Hazel next to each other and have added these photographs from my phone. The damage to both is considerable but I know the beetles were only starting to climb up the Alder a few weeks ago, while conditions were still quite cool. I should think there were hundreds, but Alder can cope with that unlike other trees, and it will be interesting to see how the Hazel fares in comparison.

Anyway, I have a partly written article to finish on this very subject - just so I can use the word plasticity :) - so if you record A.alni from any other tree species I'll be pleased to know.

Also - thanks for posting Steve. This forum has been a bit moribund lately.

Cheers,
Don

Attachments
A.alni on Hazel 24.04.2014 web.jpg
A.alni on Hazel - 24/04/2014
A.alni on Alder 24.04.2014 web.jpg
A.alni on Alder - 24/04/2014
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Re: Is Alder Leaf Beetle Extending Its Food Plant Again ?

Postby SteveMcBill on Fri Apr 25, 2014 6:39 am

Many thanks for the clarifications and extra information Don - appreciated mate.

I will look forward to your paper.

Cheers.

Steve

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