Assessment and Distribution of Damages Caused by the Trunk-Boring Insects Coraebus undatus (Fabricius) (Coleoptera: Buprestidae) and Reticulitermes grassei Clément (Blattodea: Rhinotermitidae) in Mediterranean Restored Cork-Oak Forests

Abstract

This work assesses damage caused by Coraebus undatus (Fabricius) (Coleoptera: Buprestidae) and Reticulitermes grassei Clément (Blattodea: Rhinotermitidae) in managed cork oak forests from the southern Iberian Peninsula. Lesions were diagnosed and quantified in relation to the following features: height and orientation in the trunk, diameter at breast height, solar exposure, understory presence and orography. The distribution patterns of lesions in the study area across 12 plots and in the trunk of the trees were also analyzed. The study was performed in “Sa de Hornachuelos” Natural Park (Córdoba, Spain) and the research area encompassed 12 environmentally-restored sampling plots. Data were recorded from 2007 to 2014, with yearly sampling from late June to mid-September, corresponding to the cork extraction period, since lesions caused by these insects are well distinguishable promptly after bark removal. The results reveal that C. undatus has low population levels and a non-uniform distribution pattern in the study area as well as in the trunk of the tree. It shows preference for medium height but not by any trunk orientation. R. grassei also shows low infestation levels and a preference to affect the trunk’s base. Comparatively, C. undatus showed higher infestation levels than R. grassei. The location of damage was also different, since galleries made by C. undatus predominated at intermediate trunk heights while those of R. grassei were more frequent at lower heights. Our results further showed a low co-occurrence of both species in the same tree trunks, which could be explained in terms of overlapping in the distribution areas of both species. These results provide background information that will enable natural resources managers to detect changes and trends of these species and inform future management decisions.

Phytochemical Composition of Extractives in the Inner Cork Layer of Cork Oaks with Low and Moderate Coraebus undatus Attack

“…The presence of C. undatus galleries was identified by visual observation of the decorked stems and the inner side (belly) of the cork planks. The classification of the intensity of attack (damage index) was based on the visual observation of the debarked stem after cork removal following the methodology used by Du Merle and Attié [29] and applied in C. undatus assessments [8,9]. On each tree, four vertical lines oriented to the north, Although a few studies on C. undatus attacks have tried to link infestation and the intensity of attacks to stand characteristics, e.g., tree density, the presence of understory, solar orientation, drought stress, or tree parameters, e.g., age, diameter, height, or health status [8,9], a clear pattern has not been obtained, in part due to a high degree between tree variation regarding attack levels: For instance, in one study in eight cork oak forest plots exploited for cork production in southern Spain (Natural Park "Los Alcornocales"; Sierra Morena, Huelva), the infestation index ranged from 0.40 to 2.32 [8].…”

“…The presence of C. undatus galleries was identified by visual observation of the decorked stems and the inner side (belly) of the cork planks. The classification of the intensity of attack (damage index) was based on the visual observation of the debarked stem after cork removal following the methodology used by Du Merle and Attié [29] and applied in C. undatus assessments [8,9]. On each tree, four vertical lines oriented to the north, east, south, and west sides of the stripped part of the stem were divided into 50 cm long sections from the soil surface to a maximum height of four levels (200 cm).…”

“…undatus females lay their eggs on the surface or in cracks of the cork back (i.e., the external surface of the cork layer covering the stem) about 4 years after the previous cork extraction [7,8]. The hatched larvae perforate the layers of the cork tissue underneath the cork back to the phellogen, where they feed and grow, excavating long, sinuous galleries reaching 2 m in length and 3-4 mm in width, with a higher incidence in the stem region at a height between 0.5 m and 1.5 m [9]. Larval development lasts from chemical composition of these compounds show a very high natural variability, even among trees of the same species and forest [21][22][23][24][25][26][27][28].…”

Green synthesis, characterization, and biochemical impacts of new bioactive isoxazoline‐sulfonamides as potential insecticidal agents against the Sphodroxia maroccana Ley

“…Globally, approximately 30% of potential crop yields are lost each year due to pests, weeds, and agricultural diseases 1–3 . Indeed, in the Mediterranean area, an important number of pests can colonize cork oaks ( Quercus suber L ), causing intense stress to mature trees, especially after the cork harvesting season 4–7 …”

“…[1][2][3] Indeed, in the Mediterranean area, an important number of pests can colonize cork oaks (Quercus suber L), causing intense stress to mature trees, especially after the cork harvesting season. [4][5][6][7] Mediterranean cork oak forests are one of the world's most interesting biodiversity hotspots, cork oak forests, and woodlands cover a large area approximately 2.2 million hectares across the central and western part of the Mediterranean Basin and North Africa, in Morocco, Algeria, and Tunisia, and are mainly exploited for cork extraction, with management systems that vary from semi-natural to pastoral. 8,9 The decline of cork oak trees is a prevalent issue across their entire distribution range and is primarily caused by poor management and unfavorable weather conditions.…”