ECONEX CERAMBYX 60 DAYS

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CERAMBYX SPP. - Great capricorn beetle

Cerambyx is a genus of coleopterons belonging to the Cerambycidae family.  It comprises of around 35 species distributed in the Western Palearctic zone.  In Europe there are seven species: C. carinatus (Küster, 1846); C. cerdo (Linnaeus, 1758); C. dux (Faldermann, 1837); C. miles (Bonelli, 1823); C. nodulosus (Germar, 1817); C. scopolii (Füsslins, 1775) y C. welensii (Küster, 1846).  On the Iberian Peninsula only three species can be found; C. welensii, C. cerdo and C. miles.

It is about large sized coleopterons, able to surpass 5cm in length, without counting the antennae.  The morphology of the three Iberian species is very similar and a detailed examination of certain structures to be able to differentiate them is needed, which has led to confusion in numerous references.  In accordance with Vives (2001) C. cerdo is the most common species on the Iberian Peninsula, being present in all the Holm-Oaks and Oaks, including the ones in Majorca. C. welensii has a more restricted distribution, being present in the Baetic mountain range, the Sierra Morena mountain range, the Central System, Alentejo and Algarve, the Galaico-Leoneses mountain range, the Cantabrian mountain range, the Pyrenees, the Ebro Valley and the Iberian System.

BIOLOGY

The biology of both species is very similar. The adults are active during twilight, although in accordance with (González et al, 2015), in Majorca, C. cerdo seems to be more active during daylight.  After copulation, the females place the eggs under the bark of the trunk and the thickest branches of various species of leafy trees, such as, Fagus, Castanea and Ulmus, although they are more often found on any species of Quercus. They have also occasionally been cited on Corylus and Ceratonia.

After hatching, the larvae begin to feed on the bark, entering later on in the wood to stay there for two or three years, until reaching a very large size, up to 7cm.  Meanwhile, each larva would have excavated a good number of elliptical section galleries of great size.

When the larva goes to change its stage to pupa, it excavates an exit hole in the tree.  Afterwards, it returns to the gallery on the inside of the wood to pupate in safety with sufficient protection.  The pupa hatches in autumn, but the imago remains in the gallery throughout winter until it emerges at the beginning of summer.

DETECTION AND MONITORING

In forests 1 or 2 CROSSTRAP^® XYLOPHAGOS traps per hectare should be installed. The baited traps should be present in the forest between June and August, depending on the target species.

Monitoring efforts can be intensified by placing up to 3 traps per hectare, with distances between traps from 100 to 500 m.  The traps will be installed on trees with signs of attack, for which the presence of exit holes and sawdust at the base of the trees have to be looked at especially.

Dry captures are recommended and a weekly or fortnightly assessment of the traps to avoid interfering with the wildlife.

NECESSARY MATERIAL

CROSSTRAP^® XYLOPHAGOS trap

Attractant diffuser ECONEX CERAMBYX 60 DAYS.

DAMAGES AND ELEMENTS OF DIAGNOSIS

The adults can be observed licking the exudation from the tree canker in trees, generally affected by wounds through bad pruning. The adults place the eggs close to these open and exuding wounds, as a way of accessing its main food resource, xylem.

The infested trees with initial attacks do not show any symptoms whatsoever.  As the population and size of the larvae increases, so does the build-up of sawdust.  After the first emergence of the adults, the exit holes and a large abundance of sawdust are clearly observed. These insects can carry on reproducing or years on the same trees, given that the larvae feed on the xylem, not delivering a direct and immediate death to the tree.  The crown of the affected tree, or a part of it only affects a thick branch, it starts losing its vigour and defoliation becomes more obvious as the years go by.  With the destruction of the xylematic veins the amount of water going to the crown of the tree decreases and it reacts by reducing its number of leaves.

But a tree in these conditions can last for many years. The trees affected by Cerambyx tend to die for another reason, induced by the loss of biomechanical resistance of the wood perforated by the larvae. This silent loss of resistance accumulates until it produces a tear from the main system of foliage.

In fact, the branches that break are the larger ones, given that they weigh more.  Sometimes the trees split lengthways through the middle, literally. Therefore, it's about a slow process, hidden and silent, that takes many years to manifest itself, given that it is a build-up and that, in an instant it can end the life of a one hundred year old tree..

These attacks are of great importance in the open woodlands and Cork Oak stands of occidental Andalusia, Extremadura and the Holm Oak forests of the Balearic Islands.

One detail to take into account is that the Cerambyx cerdo species is protected in the European Union by being included in the Berne Convention, annex 2: “Strictly protected species” by the Habitats Directive in the annexes 2: “Species of community interest” and 4: “Species subject to strict protection” and classified as Vulnerable by the IUCN - International Union for Conservation of Nature.