XYLOSANDRUS COMPACTUS AND LIPARTHRUM COLCHICUM (COLEOP- TERA SCOLYTINAE) IN TUSCANY: A PRELIMINARY SCREENING OF ASSOCIATED FUNGI

Xylosandrus compactus and Liparthrum colchicum are two Scolytinae recorded for the first time in Italy in 2011 and 2019, respectively. X. compactus is an “ambrosia beetle” causing damages to several plants typical of the Mediterranean maquis through its digging activity on twigs and branches of the host plants. L. colchicum is a “bark beetle”, monophagous on laurel shrubs and trees. During a survey performed in summer of 2020, in “Tenuta Salviati” located in the Migliarino Natural Park (Pisa, Tuscany), adults of X. compactus and L. colchicum were collected from the same branches and apical twigs of Laurus nobilis hedges. The study aimed at characterizing fungi isolated from the external surface of the two scolytids bodies, to evaluate similarities and even their role in fungal spreading in the environment.

Bioactive specialized metabolites produced by the emerging pathogen Diplodia olivarum

A new cleistanthane nor-diterpenoid, named olicleistanone (1), was isolated as a racemate from the culture filtrates of Diplodia olivarum an emerging pathogen involved in the aetiology of branch canker and dieback of in several plant species typical of the Mediterranean maquis in Sardinia, Italy. When the fungus was grown in vitro on Czapek medium olicleistanone was isolated together with some already known phytotoxic diterpenoids identified as sphaeropsidins A, C, and G and diplopimarane (2-5). Olicleistanone was characterized by spectroscopic methods (essentially 1D and 2D NMR and HR ESIMS) as 4-ethoxy-6a-methoxy-3,8,8-trimethyl-4,5,8,9,10,11-hexahydrodibenzo[de,g]chromen-7(6aH)-one. When the fungus was grown on mineral salt medium showed to produce (-)-mellein (6), sphaeropsidin A and a very low amount of sphaeropsidin G and diplopimarane. Olicleistanone (1) exhibited remarkable activity against Artemia salina L. (100% larval mortality) at 100 µg/mL. In addition, it did not exhibit phytotoxic, antifungal and antioomycetes activity. Among the metabolites isolated (1-6), the sphaeropsindin A (2) proved to be active in all bioassay performed exhibiting remarkable phytotoxicity on Phaseolus vulgaris L., Juglans regia L. and Quercus suber L. leaves at 1 mg/mL. Moreover, it completely inhibited the mycelial growth of Athelia rolfsii, Diplodia corticola, Phytophthora cambivora and P. lacustris at 200 µg/plug. It was also active in the Artemia salina assay. In this latter assay, diplopimarane (4) and sphaeropsidin G (4) were active (100% larval mortality). Diplopimarane also showed antifungal and antioomycetes activities. Athelia rolfsii was the most sensitive species to diplopimarane. Sphaeropsidin C (3) and (-)-mellein (6) were found to be inactive in all bioassays. Results obtained in this study have allowed us to expand the knowledge on the metabolic profile of Botryosphaeriaceae members and characterize the main secondary metabolites secreted in vitro by D. olivarum for the first time.

First record of the black twig borer, Xylosandrus compactus (Coleoptera: Curculionidae, Scolytinae) in Spain

We present the first record for Spain of the black twig borer, Xylosandrus compactus, an ambrosia beetle of Asian origin, collected from an infested carob tree located in Calvià (Majorca, Balearic Islands, Spain). X. compactus is included in the EPPO Alert List, and it has been recently reported causing damages in a Mediterranean maquis ecosystem in Italy and Southern France. Here, we discuss about the first steps of management of this Invasive Alien species (IAS), the eradication plan and the hypothesis of the path of introduction in this Western Mediterranean island.

Grazing effects on woody and herbaceous plant biodiversity on a limestone mountain in northern Tunisia

Mediterranean maquis vegetation is highly biodiverse, but widespread grazing poses a challenge for management and conservation. We sampled woody and herbaceous plants separately on a limestone mountain with strong mesic-xeric gradients in Tunisia’s Parc National de L’Ichkeul, assessed grazing pressure (on a scale of 1–3), and asked whether grazing had a significant effect on plant compositional abundance before and after controlling for environmental covariates. Sites on the more mesic lakeside face of the mountain were most compositionally unique, and forbs contributed most to the herbaceous beta-diversity on the mountain. We used variance partitioning to separate the collective and individual effects of the abiotic environment, grazing, human activity, and space on herbaceous and woody beta-diversity. However, the individual effect of grazing on overall plant community composition was confounded with space, due to the spatially autocorrelated grazing pressure on the mountain. Importantly, we found that herbaceous and woody communities responded differently to increasing levels of grazing intensity: herbaceous beta-diversity was highest between sites with no grazing pressure, while woody beta-diversity peaked under light grazing. Herbaceous community composition was sensitive to any intensity of grazing pressure, and biotic homogenization occured under moderate-to-high grazing pressure. On the other hand, woody community composition remained relatively similar under no to light grazing pressure, but differed under moderate-to-heavy grazing. Using a one-way permutational analysis of variance analysis, we showed that grazing had a significant effect when controlling for abiotic and spatial covariates. Our findings offer insight into the effects of grazing on maquis vegetation at Jebel Ichkeul, acting as a microcosm of similar conservation and management issues elsewhere in the Mediterranean. We suggest that a combination of monitoring and carefully controlled grazing may enhance plant diversity and maintain the region’s biodiverse maquis vegetation, potentially maintaining a key climate refugium for vulnerable endemic species. Importantly, our study provides a useful baseline of the plant assemblages at Jebel Ichkeul with which to compare future vegetation changes.