Pine longicorn (Monochamus galloprovincialis)

two insects with very long antennae and called Monochamus galloprovincialis

El Monochamus galloprovincialis it is a tiny insect, specifically a beetle, which serves as a vector to carry from one pine tree to another a tiny worm that is capable of killing hundreds of conifers and other tree species in a very short time.

It is a species that comes from North America, as microscopic as it is lethal. This beetle called also pine longicorn, belongs to the family of cermbicides, whose radius of action does not exceed more than 3 kilometers in its entire life.

Features Monochamus galloprovincialis

image of a pine tree where its completely dry branches are seen

During their adulthood, these insects reach the conifers laden with the tiny worms in their antennae, which in turn come from a tree that is already infected.

Once there, nematode or worm accesses the interior of the tree using the hyphae of the fungi, which are usually in them and also, penetrating through the wounds that these trees have, that is, any crack present on the surface of the bark is good to enter and infect the plant.

At the same time, this in its invasive process, gives rise to a series of galleries in the inner part of the pine trunk, which makes it lose a good part of its attractiveness and commercial value even when it receives treatments with chemical products.

How does it affect the plant?

When microscopic nematodes enter the pine tree, completely invade the resin channels and there they feed on the parenchyma present in these channels, as well as on the epithelial cells. When the resin canals are affected, there is no more production of resin, which prevents the perspiration of the needles.

Coming Soon, pine begins to show unmistakable signs of infection, looking withered and a yellow color in the atria. It would still be possible to observe brown to yellow needles on the branches, however, in a maximum of 3 months the tree will have died.

This small organism has a high capacity for adaptation thanks to its tremendous plasticity. To get a good fit, a temperate climate is enough that is located over 20 degrees in summer season, being easier to distribute at altitudes lower than 1.000 meters.

For these reasons is that nowadays it is very common to notice their presence in the southern region of Pontevedra and also in Extremadura, where the mortality of the trees between July and August when temperatures oscillate between 20 and 25 degrees, is evident.

In addition, there are other elements that favor this nematode to settle and it develops rapidly in the pines, these being the absence of rain, which generates stress in the pines during the summer.

What to do if the infection is detected in the trees?

If the pine is found to be infected, the authorities must be informed immediately competent in forestry matters to initiate the corresponding actions that the case warrants.

What is done in these cases is determine the so-called zone A, which ranges from 1 to 2 kilometers within the radius where the focus was detected. There, the eradication measures that are available must be applied, among them the felling of pines is the most radical and at the same time effective.

This felling is carried out in a radius that includes the first kilometer of the source of infection, which prevents the beetle from moving forward. There are even sites where logging of up to 1,5 kilometers is carried out, even when this affects high-productivity hectares.

It is noteworthy that in the winter season, this nematode tends to fall into a kind of lethargy, but once the temperatures begin to be higher, when it reaches the optimal conditions it will surely expand. For this reason, felling must be done as soon as possible.

In parallel, other actions are taken that serve to eradicate the possible sources of food for the vector. Monochamus galloprovincialis, consist of the elimination of dead trees or in process in a radius of 20 kilometers.

All this wood that has been felled in these 20 kilometers that are assumed to be quarantined, is limited for sale unless they receive a treatment that passes subjecting it to high temperatures inside chambers, which leads to the death of the parasite if they are still inside said pieces of wood.

When did the spread of this plague start?

insect on a cut trunk of a dead pine

It began in 1999 in Portugal, where there are large areas of trees that have been severely affected, which in fact in 2018, it already covered a territory greater than half. On the other hand, in Spain for this same year there were 6 specific sources at a critical level located in Extremadura, Castilla y León and Galicia.

Regarding the areas with the greatest potential for the infection to spread in Spain, these are very well identified according to a propagation model which has the validation of the UPM and the Joint Research Center of the European Commission.

This model has been very useful since it allows us to predict which are the areas where the pest would be most likely to enter Spain, based on known infected areas in neighboring Portugal and in which no effective control measures have been taken.

Unfortunately, this scientifically known nematode, expert in causing damage to pine wood, has joined with this other species, which It serves as the ideal vector to be able to go to different trees where it is established with always fatal outcomes for it, since it ends up dying in a very short time.

This vector is nothing less than a small common beetle in the fauna of Spain, which is popularly called the longicorn of the pine thanks to its long antennae. This small typical insect of the countryIt gets its source of food in the tender branches of the pine and from time to time in its desire for food, it carries the microscopic parasite from tree to tree.

But it is not all that it does to facilitate the spread of the nematode, since both beings have their life cycle tied to that of the otherThat is, while the beetle provides new trees to the parasite which would be impossible to reach, it rewards its work with weak specimens where it can lay, which would not be possible in a healthy one since the normal pressure of suppuration of the resin would not allow it.

The nematode once inside the tree unleash a voracious appetite and it reproduces at shocking speeds, which in equal measure generates irreparable damage by preventing the flow of water through the tree, ending its life very quickly.


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