Ranean plus the Supra-Mediterranean belts and show affinity to siliceous, loose and permeable substrates standard of hygrophilous environments. Though there exist pure or almost pure formations of Q. suber, this species is often also integrated in mixed Quercus formations, where can coexist with diverse species such as Q. ilex an Quercus faginea (Lamarck), maintaining the typical physiognomy on the dehesa [10]. The conservation status of dehesas is threatened, among other variables, by the progressively a lot more evident “decline syndrome”, which consists in the development of a set of decay symptoms that happen with out a fixed pattern but following a sequential chronology. The main causes of this decline happen to be categorized in 3 groups which act synergically [11]: I. II. Predisposing elements to which the trees are permanently exposed, like harsh climatic situations, edaphic adjustments and inadequate silvicultural practices; Aggravating elements which act for the duration of a quick but intense period of exposure, including the action of defoliating insects for instance the Lepidoptera Lymantria dispar (L.) and 3MB-PP1 supplier Tortrix viridana L. and insect borers such as C. undatus (our study topic); Contributing things, which result in death of poor health or weakened trees, like pathogenic fungi of the genus Phytophthora and Pythium.III.In the course of the last decades, the decline of Quercus spp. has impacted millions of specimens throughout their distribution location [12], which has got an incredible financial repercussion, lessening the cork production involving 40 and 89 , depending on the geographical zone. The cork oaks affected by this syndrome are additional vulnerable to endure the attack of pathogens, defoliators and xylophages. Adults of C. undatus are diurnal, thermophiles and herbivorous oligophagous [13]. The adults emerge in spring from inside of trunks and most important branches, causing exit holes “D” shaped in the bark. The females lay eggs on the bark Ganoderic acid DM Autophagy surface or inside cracks. Just after hatching, the neonatal larvae move towards the phloem and begin to feed by constructing characteristic tunnels. Normally, the larva goes by way of 4 stages just before winter and, following the last phase, the larva remains inside a quiescent state or pupa until late spring, when it emerges as an adult [14]. Though C. undatus can feed on a number of Quercus species, its damages produce greater financial losses in the case of the cork oaks. Throughout their development, they elaborate sinuous feeding galleries within the phellogen layer, reaching even 2 m length and three mm width, harming the regenerative capacity of the tree [4]. Inside the following years, it may be observed that the new layers of cork show hypertrophied locations corresponding towards the galleries filled with excrements. These scars, normally known as `cork shingles’ as a result of its sinuous morphology (Figure 1a), substantially devalue the cork price tag, therefore threatening the sustainable exploitation of cork-oaks forests [15]. Variables influencing the presence of C. undatus are tree density, presence of understory, age, well being and height of trees, solar orientation and drought stress [16]. Like within the case of other borers, the handle of C. undatus is complicated to carry out because the larva (damaging stage) is endophytic, undetectable and practically inaccessible [17,18].Forests 2021, 12,3 ofFigure 1. Lesions in Q. suber trunk performed by boring insects. (a) “cork shingles” by C. undatus, in which three interceptions are visible; (b) “chicken feet” by R. grassei, with one particular interception vi.