sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDÜ ORMAN FAKÜLTESİ DERGİSİ
Damage to our native American beech was first observed 20 years later. The
pathogen was thought to be the exotic fungus Neonectria coccinea from Europe,
but recent taxonomic studies showed that the new species Neonectria faginata
(=Nectria coccinea var. faginata) is the pathogen of this BBD complex in North
America (Castlebury et al., 2006). Also, N. ditissima (=Nectria galligena), a
pathogen causing cankers on Acer spp. and Betula spp. in North America, is often
involved in the BBD (Houston, 1994).
A B
Figure 1: A- The beech scale insect Cryptococcus fagisuga colonizing the bark of the
American beech (Fagus grandifolia). B- Multiple small cankers caused by Neonectria
faginata.
The control of BBD is not an easy task. Different approaches have been
considered. The selection and propagation of resistant beech is one of them (Koch
and Carey, 2005; Loo et al., 2005). Using silviculture to improve the health status
of beech populations in newly infested stands (Heyd, 2005) or aftermath forests
(Ostrofsky, 2005) is a second approach. Biological control of the scale insect and
fungal pathogens is a possibility that has been suggested in the past, but so far only
preliminary trials have been reported (Lonsdale, 1983).
In our project, we are testing different entomogenous fungi and hyperparasite
fungi to control the insects and the pathogens involved in the BBD complex. The
objective of this study is to use entomogenous fungi to reduce the population of C.
fagisuga under laboratory conditions.
2. MATERIALS AND METHODS
Since the entomogenous fungus Lecanicillium muscarium (= Verticillium
lecanii Vegas) was observed to be common in heavily infested sites in England
(Lonsdale, 1983), it was retained in our first experiment on the non-crawling
nymphal stage. This instar is a crawling immature but has its stylet fixed in the
bark and produces the typical “wool-like” wax. We are using the isolate L.
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