A plague on the forests

An insect is killing off pine trees in Attica and many other parts of southern Greece, while the Agriculture Ministry just watches. Marchalina hellenica is an insect that secretes a honey-like substance considered useful in the production of pine sap. But large numbers of them attack pines, which are then invaded by deadly parasites. Since 1997, the Agriculture Ministry has funded the introduction of the insect into pine forests to boost pine-sap production. But the insects escaped the pine forests and attacked suburban forestland and national parks. In contrast to northern Greece, where the pines recover faster, the trees in southern Greece recover slowly or not at all. Experts said the situation was out of control and recommended using organic spray on the pines, but the ministry halted the project under pressure from the Panhellenic Federation of Beekeepers. Halandri residents took action after seeing the pine forest of Rematia (where there are no bees) slowly dying out. The same is happening to pines in Filothei, Psychico, Vrilissia, Holargos, Aghia Paraskevi, Parnitha, Faliron, Nea Smyrni, the Aegean islands, Crete and elsewhere. The usual method of dealing with the problem is to hose down the trees, which gives them a rest but doesn’t save them. According to the Institute for Mediterranean Forest Ecosystems and Forest Product Technology at the National Agricultural Research Foundation (ETHIAGE), when the dead bark comes off the tree, it is easier for bark-eating caterpillars (parasites) to establish themselves in the tree, which they eventually kill. Moreover, the insects that have been removed by washing are free to colonize other trees. The institute has cooperated with the pharmaceutical department of Athens University on developing a method of dealing with Marchalina hellenica populations by using organic methods rather than harmful agricultural chemicals. It involves spraying pine trees with organic sprays made of plant oils taken from thyme and mastic that make the plant seem unfamiliar to the insects and which ensures that their natural predators are not reduced, so that the insects leave the tree. The Halandri Municipality, which did not hose down the trees on the grounds that washing was not a definitive solution to the problem, gave its approval to organic spraying, but the project was never implemented. According to an announcement by the municipality, the ministry put a stop to the project because of protests by beekeepers. «The pine forest of Rematia is not the property of the Halandri Municipality, or of the Beekeepers’ Federation; it’s public property,» Maria Antonopoulou, member of the Halandri Citizens’ Committee told Kathimerini. «Besides, if the trees die there won’t be any bees!» As ETHIAGE scientists point out, the insects should not have been introduced into the pines before their effect on different-sized populations had been researched. They recommend a system of monitoring such «inoculations.»