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.


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