PINE
DISEASES
The pine forests of Parnitha occupy a huge area of the National Park. Unfortunately, the appearance of harmful insects the past years, threatens their evolution. The insect Marchalina hellenica
and the caterpillar of the moth Thaumetopaea pityocampa
are mainly responsible for the death of numerous aleppo pines in the mountain.
The insect Marchalina hellenica (Coccina, Margarididae) is a pine parasite that produces sweet excretions, collected by the bees and converted in honey, known as pine-honey. The presence of this insect has been verified only in countries around the Mediterranean and particularly in Greece, Turkey and South Italy. It parasites the species Pinus brutia, Pinus
halepensis, Pinus silvestris,
Pinus pinea, and there is only one record for Pinus nigra. The importance of this insect for Greece is big, because the honey being produced from it, is 65%
of the total honey produced in the country.
The disease caused by the particular insect is called vamvakiasi (from the Greek noun "vamvaki"=cotton), as its excretions look like small pieces of cotton on the trees. Natural insect’s populations are not harmful for the pines, but the Ministry of Agriculture funded the beekeeping associations to deliberately infest the pines with this parasite, in order to increase honey production. This plan resulted to the dramatic increase of Marchalina hellenica‘s populations. Formally, there is no specific damage known to the trees by it, however it seems that the insect lives by sucking the sap of the trees, contributing to their decay, when they are possibly infected by pathogenic fungi or other microbes.
The moth Thaumetopaea
pityocampa is a herbivore insect,
living in the Mediterranean countries, Portugal and areas of Switzerland, Hungary and Bulgaria.
In our country, it has been found in almost all the pine-forests, up to 1,800 m. It damages the trees with its eating habit. The caterpillars can cause foliage loss up to 20-45%, which can lead even to the death of young trees.
Apart from the damage done on the trees, the caterpillar’s hairs can cause serious health problems to humans, such as eczemas, various rushes, respiratory disorders and eyesight problems. The methods for handling the caterpillars, are:
•
Biological: either the bacterium Bacillus thurigiensis is used, to stop the caterpillar’s growth or pheromones (a substance secreted by the female to attract the male), in order to guide the insects into special traps.
• Chemical:
insectisides with Diflubenzuron are used.
They inhibit the chitin composition, so that the insect is unable to evolve and dies.
• Mechanical:
it is the most environmental-friendly way, as it is based in cutting down and burning the coccoons.
