melolontha melolontha

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Laura Purdy

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melolontha melolontha
« on: September 21, 2013, 11:41:31 AM »
Our walnuts are being ravaged by this pest. We tried a pesticide recommended by a geoponos (we're in Greece), but it was probably too late, and in any case we are trying to be as organic as possible. After some searching, I read that this is a larva of a beetle, which descends from the trees when it gets cold, and buries itself in the ground around it. Apparently they are fragile and can be destroyed by plowing around the tree. We'll try this, but in the meantime, has anybody else used any other methods to kill this thing? I gather it will also attack figs, mulberries, palms, and who knows what else.

Grateful for any further information!

Alice

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Re: melolontha melolontha
« Reply #1 on: September 21, 2013, 05:50:12 PM »
Laura, we imported some of the grubs of this chafer beetle with vine waste we wanted to turn into compost. These larvae are about 2.5 cm long, fat, white and curled into a C-shape. I was rather worried when I first identified them but they don't seem to have done much damage. I usually squash the grubs when I find them and you can collect the adult beetles and kill them too. I understand there is a nematode which can be used to control them but I have not tried this method. Also, why not try neem oil as a spray. It has been discussed previously on this forum. Good luck.
Amateur gardener who has gardened in north London and now gardens part of the year on the Cycladic island of Paros. Conditions: coastal, windy, annual rainfall 350mm, temp 0-35 degrees C.

David Bracey

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Re: melolontha melolontha
« Reply #2 on: September 23, 2013, 06:32:37 PM »
Walnut trees are usually the size of forest trees.  If so it would seem to me to be a waste of time trying to control the adult beetle in the tree thats assuming you can buy an effective insecticide. 

There two nematodes which could be used. Nematodes need water to move in the soil so wait until it has rained or try to water-in the product.  The most effective nematode is Heterorhabditis. There are several species.  Another nematode is Steinernema whichis more commercialy available but less effective irrespective what is claimed. They both require warm temperaturestowork.

You will have to search the internetfor suppliers.  I will also look.
MGS member.

 I have gardened in sub-tropical Florida, maritime UK, continental Europe and the Mediterranean basin, France. Of the 4 I have found that the most difficult climate for gardening is the latter.

David Bracey

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Re: melolontha melolontha
« Reply #3 on: September 23, 2013, 07:05:51 PM »
Here are two websites www.biocontrol entomology.edu/pathogens/nematodes.html and
www.biconet.com/index.html
MGS member.

 I have gardened in sub-tropical Florida, maritime UK, continental Europe and the Mediterranean basin, France. Of the 4 I have found that the most difficult climate for gardening is the latter.

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JTh

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Re: melolontha melolontha
« Reply #4 on: September 23, 2013, 07:24:01 PM »
I immediately thought that some kind of light traps could be useful here, since it is known that adult Melolontha melolontha seems to be attracted to light at night. In addition, the females send out strong pheromones which attract the males, and these could also be used in traps early in the season to catch the males before mating. After a little bit of searching I actually did find a couple of articles about traps for these chafers:

Optimized trap lure for male Melolontha cockchafers (A. Reinecke,  J. Ruther,  C. J. Mayer,  M. Hilker). Journal of Applied Entomology (Volume 130, Issue 3, pages 171–176, April 2006)

and

Light-trap Catch of the Common Cockchafer (Melolontha melolontha L.) Depending on the Atmospheric Ozone Concentration. (PUSKÁS, János | NOWINSZKY, László). Acta Silvatica & Lignaria Hungarica. Volume: 7; Start page: 147; Date: 2011;

There even seems to be a Barcelona-based company called OpenNatur which sells traps online (http://www.opennatur.com/en_phyllopertha_horticola_melolontha_melolontha_gusanos_blancos_del_cesped.html).
I have of course no idea how efficient these may be, they use kariomones for mass trapping of both male and female cockchafers.
Retired veterinary surgeon by training with a PhD in parasitology,  but worked as a virologist since 1992.
Member of the MGS  since 2004. Gardening in Oslo and to a limited extent in Halkidiki, Greece.

Laura Purdy

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Re: melolontha melolontha
« Reply #5 on: October 07, 2013, 09:02:32 AM »
Thanks, all! I will try to find a Greek source for nematodes, and light traps. (Does anybody know of any? I suspect that shipping from the US would take too long for the nematodes.)