The urgent need to increase the sustainability of crop production has pushed the agricultural sector towards the use of biostimulants based on natural products. The current work aimed to determine whether the preharvest application of two commercial formulations, based on a Fabaceae enzymatic hydrolysate or a blend of nitrogen sources including fulvic acids, and two lab-made aqueous extracts from Moringa oleifera leaves (MLEs), could improve yield, quality, and storability of lettuce grown in a hydroponic system, as compared to an untreated control. Lettuce plants treated with the MLEs showed significantly improved quality parameters (leaf number, area, and color), total phenolic content and antioxidant activity, and resistance against the fungal pathogen Botrytis cinerea, comparable to that obtained with commercial formulates, particularly those based on the protein hydrolysate. A difference between the M. oleifera extracts was observed, probably due to the different compositions. Although further large-scale trials are needed, the tested MLEs seem a promising safe and effective preharvest means to improve lettuce agronomic and quality parameters and decrease susceptibility to rots.

Endophytes are symptomless fungal and/or bacterial microorganisms found in almost all living plant species. The symbiotic association with their host plants by colonizing the internal tissues has endowed them as a valuable tool to suppress diseases, stimulate growth, and promote stress resistance. In this context, the study of culturable endophytes residing the sapwood of Apulian olives might be a promising control strategy for xylem colonizing pathogens as Xylella fastidiosa. To date, olive sapwood cultivable endophytes are still under exploration; therefore, this work pursues a study of cultivable endophytes occurrence variation in the sapwood of different olive varieties under the effect of seasonality, geographical coordinates, and X. fastidiosa infection status. Our study confirms the stability of sapwood endophytic culturable communities in the resistant olive variety and presents the seasonal and geographical fluctuation of olive trees’ sapwood endophytes. It also describes the diversity and occurrence frequency of fungal and bacterial genera, and finally retrieves some of the sapwood-inhabiting fungal and bacterial isolates, known as biocontrol agents of plant pathogens. Thus, the potential role of these bacterial and fungal isolates in conferring olive tree protection against X. fastidiosa should be further investigated.

Early detection of Xylella fastidiosa outbreaks in Apulian olive groves is crucial, especially in buffer zones and pathogen-free areas where olive trees are asymptomatic. Three studies were conducted. Two were on the spatial and temporal progression of X. fastidiosa infections in tree canopies of asymptomatic or mildly symptomatic olive trees of tolerant (‘Leccino’) and susceptible (‘Cellina di Nardò’ and ‘Ogliarola salentina’) cultivars. Despite different trends in pathogen infection rates and concentrations between ‘Leccino’ and susceptible olive cultivars over the study period, results showed that sampling was most effective in the mid-upper part of tree canopies throughout the year, excluding the warmest and coldest periods. Stem xylem tissues were the most appropriate for detecting the pathogen compared to lower parts of mature leaves with petioles, using serological and molecular assays. Based on these results, a third study was conducted to compare molecular and serological tests (qPCR, real-time LAMP, DAS-ELISA, DTBIA) for detection of X. fastidiosa in the mid-upper part of asymptomatic branches of infected ‘Leccino’ trees that were sampled in an appropriate collection time, using stem xylem tissue as the most appropriate matrix for testing. The molecular methods showed the greatest sensitivity, with no undetermined results, while among the serological assays, DTBIA was more sensitive than DAS-ELISA. An improved protocol for monitoring asymptomatic olive trees is recommended.

Honey bees (Apis mellifera) are key pollinators in agricultural ecosystems that face increasing pressure from pathogens and environmental change. However, how these environmental factors interact remains incompletely understood. To assess associations between climate, landscape composition, and pathogen occurrence in real agroecosystems, we monitored honey bee colonies across 30 apiaries in southern Italy over two years, in summer and autumn. Molecular screening revealed widespread multi-pathogen exposure, with two viruses, Black Queen Cell Virus (BQCV) and Deformed Wing Virus (DWV), and gut trypanosomatid parasite (Lotmaria passim) being the most frequently detected. In contrast, Nosema ceranae, along with Bee Macula-like Virus (BeeMLV) and Acute Bee Paralysis Virus (ABPV), occurred at lower but still notable frequencies. Infections were generally more frequent in adult foragers than in in-hive bees and larvae, and overall pathogen occurrence tended to be higher in summer than in autumn. Higher humidity was associated with higher overall pathogen occurrence and coinfection levels, whereas higher temperature showed a weaker association with these outcomes. Associations between landscape composition and pathogen occurrence differed across pathogens: a higher proportion of semi-natural habitats was associated with lower viral occurrence, particularly BQCV and DWV; however, N. ceranae was more frequently detected under the same landscape conditions. In contrast, L. passim showed context-dependent responses, with landscape effects emerging only through interactions with humidity and temperature. Pathogen coinfections were more occurrent under warm, humid conditions, although this pattern was partially buffered in landscapes richer in semi-natural habitats. Together, these results indicate that, within the studied apiaries, honey bee pathogen occurrence was associated with climate, season, and land use. These findings suggest that environmental context should be considered when interpreting honey bee health monitoring data in heterogeneous agricultural landscapes, with potential implications for apiary management.