NEWS
Several new locations discovered for Andricus aries around Amsterdam, Utrecht and in the province Zeeland!!
Map: present knowlegde
of occurence of Andricus aries in the Netherlands.
Last 19th of November
2006 many specimen of Ram's Horn Gall (Andricus aries)
where found in the Thijssepark
and the Amsterdamse Bos in Amsterdam!!
Untill now only one place was known for Andricus aries, on a small oak
in the Diemerpark, discovered in Spring 2003. In the
Thijssepark I checked most of the oak trees and shrubs present and I found
galls on three small and large shrubs of oak. On a seedling oak 40 cm
high) ten galls (see picture) where present. They did not seem to be parasitised,
since they where slender and had long 'horns'. On the other (larger and
older) shrubs in the park the galls were nearly all very stubby and extra
thickened at the base. These galls were probably parasitised by other
wasps. It is also possible the elder oak trees have better resistance
to galling parasites like Andricus aries, and the galls are not
able to develop to a healty state. Several of the galls on the older shrubs
haddn't emerged and probably never will.
In the Amsterdamse Bos ('Wood of Amsterdam') I found galls of Andricus aries on two (average) large oak trees. These galls were also stubby and extra thick at the base.
In 2006 Willem Ellis en Berend de Vries found a gall in the Diemerbos (Telegraafbos). Several thousands of oak trees were planted there in 1993.
Galls are also found in Purmerend and Haarlem in February 2007.
In June 2007 galls were found in Hillegom and in August 2007 galls were found near Middelburg in the province of Zeeland.
On 20 October 2007 galls were found on estate Nijenrode at Breukelen by Jan Willem Wertwijn!!!
E-mail: Jojanneke@plantengallen.com
(Picture: Rams Horn
galls in Jac. P. Thijssepark)
(Picture: A. Koper, Haarlem)
(Picture: D. Vonk, Haarlem)