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13 February 2003, Rome -- A pest that had been ravaging the emblematic
cedars of Lebanon, Cedrus libani, is finally under control after
a battle lasting nearly five years. Cephalcia tannourinensis, a
wood wasp, threatened to wipe out most of Lebanon's cedar
forests and spread to neighbouring countries. But with technical
help from FAO, a team of scientists from the American University
of Beirut, the Lebanese Ministry of Agriculture
and French experts have joined forces to study the insect and
find ways to control it.
A
newcomer for scientists
The
insect was first discovered in 1998. Scientists found that the
insect lays its eggs on new cedar buds and when the buds open,
the larva feeds on the cedar needles as it develops. It then
drops to the ground and buries itself to hibernate. The damaged
trees are more vulnerable to other insects' attacks and may
eventually die from defoliation.
The
preferred means of immediate control for such pests is the use
of environmentally friendly biological (non-chemical)
pesticides. However, lack of knowledge about the insect's
life-cycle -- for example, how long it hibernates underground
before emerging again to mate -- makes it difficult to plan
spraying operations in advance. Spraying is more effective in
the first and last phases of the cycle, when the insect lives
above ground.
Extensive damage
evaded
The Tannourine-Hadath
El-Jebbeh Forest in northern Lebanon is one of the largest
remnants of cedar forest in the country, with 50,000 trees
spread over 600 hectares of land. Before the control project,
the situation there was critical, as 80 percent of the
forest's cedars were infested with the pest.
The insect had also spread to the "Forest of
the Cedars of the Gods", in Bcharreh, putting its trees
at risk. Forests in Syria and Turkey were also threatened.
"As is usually the case with pest
problems," says Gillian Allard of the FAO Forestry
Department, "the symptoms appeared very late."
Prevention better than
cure
As a first step to help
control the pest, aerial biological spray operations were
conducted by the Lebanese Ministry of Agriculture in 1999, 2000, 2001 and 2002 and research
on the insect began immediately after the first aerial spray application.
FAO helped
by providing funds and expertise through its Technical
Cooperation Programme, including detailed investigation into the
pest life-cycle and trapping methods. Yellow sticky traps were
found to be particularly effective. The pests are attracted by
the colour of the traps and stick to the outer coating. The team
is also seeking to identify the composition of the insect's
pheromone - its characteristic mating attractant - for possible
use in traps.
Training of environmental
experts and foresters was another important component of the
project. They were taught how to recognize the first signs of
infestation, such as the early stages of defoliation, and were
shown the techniques available for control of this and other
pests afflicting the cedars.
Scientists
still need to answer many questions about the insect in order to
prevent new outbreaks in Lebanon and elsewhere. Their findings
will help experts identify the best tools to control future
infestations should they occur. But the alarm has sounded, and
for now at least, Lebanon's treasured symbol remains.
Contact:
FAO Media Office
media-office@fao.org
+39 06 570 53625
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