sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDU Faculty of Forestry Journal
Serial: A, Number: Special Issue, Year: 2009, ISSN: 1302-7085, Page: 194-199
BIOLOGICAL CONTROL TRIALS OF BEECH BARK DISEASE
UNDER LABORATORY CONDITIONS
Gaston LAFLAMME 1* , Simon BOUDREAULT 1 , Robert LAVALLEE 1 ,
Martine BLAIS 1 , Jean-Yves BLANCHETTE 2 .
1 Natural Resources Canada, CFS, Laurentian Forestry Centre, Québec, QC, Canada G1V 4C7
2 Université de Moncton, Edmundston, N.-B., Canada E3V 2S8
* Gaston.Laflamme@NRCan-RNCan.gc.ca
ABSTRACT
Beech bark disease (BBD) causes mortality of American beech (Fagus grandifolia
Ehrh.). BBD involves an attack by the beech scale insect Cryptococcus fagisuga Lind.
followed by the native fungal pathogen Neonectria faginata (Lohman et al.) Cast. &
Rossman. C. fagisuga was introduced into Halifax, Nova Scotia, from Europe through
seedlings around 1890. Damage to American beech was observed 20 years later. Our
objective is to use entomogenous fungi to control the insect. Lecanicillium muscarium
(Petch) Zare & W. Gams, common in European infested sites, was retained as well as
Beauveria bassiana (Bals.-Criv.) Vuill. Our first trials were done on non-crawling nymphal
stage on bark disks, 24 mm in diameter, kept individually in Solo cups ® at 20°C or 25°C.
To expose the insects, the “wool-like” wax covering the colony was removed. The
treatment consisted of an application of 125 µL of 10 6 spores/mL of water and oil. A
second trial was conducted by spraying spore suspensions of L. muscarium (100 µL) on
eggs kept at 25°C. Both biological control agents reduced the crawlers’ population by 50%
after 11 days. Eggs treated with L. muscarium showed low mortality, but their
development was slowed down. Fungi seen on the surface of the eggs invaded the first
instars. Field trials are underway.
Keywords: Beech bark disease, Cryptococcus fagisuga, Neonectria faginata,
Lecanicillium muscarium, entomogenous fungi, Beauveria bassiana
1. INTRODUCTION
American beech (Fagus grandifolia Ehrh.) forests suffer significant mortality
caused by beech bark disease (BBD); this complex disease has a permanent
negative impact on the forest ecosystem in North America. A symposium on this
important disease was held in New York State to summarize the status of our
knowledge on BBD, and to identify the most important knowledge gaps of this
phenomenon (Evans et al., 2005). Rapidly spreading across eastern North
America, BBD involves a preliminary attack by the beech scale insect
Cryptococcus fagisuga Lind. and fungal species of the genus Nectria (Ehrlich,
1934), now known under the genus Neonectria (Figure 1). The insect C. fagisuga
was introduced into Canada from Europe, around 1890, through European beech
(F. sylvatica L.) seedlings planted as ornamentals in Halifax, Nova Scotia, Canada.
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