Aphrophoridae as Potential Vectors of Xylella fastidiosa in Tunisia.

The present study is an update on the situation of potential vectors of Xylella fastidiosa in Tunisia. Investigations in nine Tunisian regions (Nabeul, Bizerte, Béja, Jendouba, Zaghouan, Kairouan, Ben Arous, Tunis and Manouba) from 2018 to 2021 allowed for the observation of 3758 Aphrophoridae among a total of 9702 Auchenorrhyncha individuals collected by sweep net. Four Aphrophoridae species were identified with Philaenus tesselatus as most abundant (62%), followed by Neophilaenus campestris (28%), Neophilaenus lineatus (5%) and Philaenus maghresignus (5%). Aphrophoridae individuals were found to be particularly abundant in both forests of Nabeul and Jendouba, secondarily in olive groves and dry grassland. Furthermore, their distribution on weed hosts was followed in these two regions where nymphs and adults are widely distributed. P. tesselatus appears to be the most abundant species as determined either by conventional sweep netting for adults or by plant sampling on Sonchus, Smyrnium, Cirsium, Rumex, Polygonum and Picris for nymphs. Limited numbers of adults of P. maghresignus were detected by sweep netting, while nymphs of this species were found on Asphodelus microcarpus only. N. campestris was found in high numbers on plants belonging to the Poaceae family in forests, dry grassland and olive groves whereas N. lineatus occurred on herbs under or near olive trees and in dry grasslands.

Exploring Active Peptides with Antimicrobial Activity In Planta against Xylella fastidiosa.

Xylella fastidiosa (Xf) is a xylem-limited quarantine plant bacterium and one of the most harmful agricultural pathogens across the world. Despite significant research efforts, neither a direct treatment nor an efficient strategy has yet been developed for combatting Xylella-associated diseases. Antimicrobial peptides (AMPs) have been gaining interest as a promising sustainable tool to control pathogens due to their unique mechanism of action, broad spectrum of activity, and low environmental impact. In this study, we disclose the bioactivity of nine AMPs reported in the literature to be efficient against human and plant pathogen bacteria, i.e., Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, against Xf, through in vitro and in vivo experiments. Based on viable-quantitative PCR (v-qPCR), fluorescence microscopy (FM), optical density (OD), and transmission electron microscopy (TEM) assays, peptides Ascaphin-8 (GF19), DASamP1 (FF13), and DASamP2 (IL14) demonstrated the highest bactericidal and antibiofilm activities and were more efficient than the peptide PB178 (KL29), reported as one of the most potent AMPs against Xf at present. Furthermore, these AMPs showed low to no toxicity when tested on eukaryotic cells. In in planta tests, no Xf disease symptoms were noticed in Nicotiana tabacum plants treated with the AMPs 40 days post inoculation. This study highlighted the high antagonistic activity of newly tested AMP candidates against Xf, which could lead to the development of promising eco-friendly management of Xf-related diseases.

Reduction of Post-Harvest Injuries Caused by Drosophila suzukii in Some Cultivars of Sweet Cherries Using a High Carbon Dioxide Level and Cold Storage.

Efficient strategies are required in sweet cherry fruits to control the spotted wing drosophila (SWD), Drosophila suzukii, due to its adverse economic effect on farmers. Cold storage (CS) and storage with elevated carbon dioxide (CO2) are environmentally safe approaches for the pest control of stored fresh fruit. These strategies are effective in controlling a wide variety of insect species, without allowing toxic compounds to accumulate. The purpose of this study was to assess the effectiveness of a post-harvest application of CO2 treatment at 50%, cold treatment at 4 °C (CT), and a combination of both (CO2-CT) in controlling the early stages of SWD within four cultivars of freshly harvested cherry fruit, namely "Burlat-Bigarreau", "Giorgia", "Ferrovia", and "Lapins". In addition, an evaluation of the quality attributes of the cherries (skin firmness, berry firmness, strong soluble material, and titratable acidity) was carried out at harvest and after 10 and 20 days of storage. All treatments significantly reduced the rate of emergence of SWD when compared to the control (untreated cherry at 24 °C), and 100% SWD mortality was obtained in Burlat-Bigarreau (CO2-CT). In addition, over the entire storage time, the quality parameters were preserved in the samples stored at 4 °C and in the samples with combined treatments in comparison with the control.