Plant defensins have attracted much attention in the development of new antimicrobials. Yet the elucidation of their modes of action against bacterial pathogens is still incipient. The available recombinant systems to obtain plant defensin mutants with enhanced or optimized antibacterial activity may help to accelerate the knowledge of their action mechanisms and their applications against pathogens. In this work, the point mutant defensin K45E (J1-1_K45E) was obtained by the same recombinant system as J1-1 defensin. The characterized peptide conserved antibacterial activity against the gram-negative Pseudomonas aeruginosa and showed a dose improvement relative to J1-1. Furthermore, the mutant J1-1_K45E exhibited a gain in function against the gram-positive Staphylococcus aureus. Finally, to correlate structural changes and antibacterial activity, two properties involved in defensins’ modes of action were measured. First, the mutant J1-1_K45E which oligomerizes in a distinct pattern was compared with J1-1 and secondly, J1-1_K45E shows a distinct lipid binding profile because it binds preferentially to phosphatidylserine. Together, our findings support the idea that amino acid sequence variability in plant defensins superfamily can generate major functional changes, and highlight the relevant role of charged residues, beyond the g-core loop, in the improvement of J1-1 antibacterial activity.

Mealybug is a renowned pest known to attack agricultural products from the field to the post-harvest process, such as on the seed rhizomes of Curcuma aeruginosa. Therefore, this study aimed to examine and identify the species of mealybug on the seed rhizomes of C. aeruginosa based on morphological and molecular characteristics. Fifty mealybugs were collected from the seed rhizomes of C. aeruginosa in the storage room in Bogor (Indonesia) using a soft brush. They were transferred to new C. aeruginosa rhizomes without any other insects present. Morphological identification based on observation of mounted specimens of 10 female adults and six for molecular identification. The primer pair that amplified the mitochondrial cytochrome oxidase I (COI) gene was used to study the molecular characteristics and was continued with direct sequencing and sequence analysis. The results showed that the morphological characteristics of the mounted specimen were close to those of Pseudococcus jackbeardsleyi. Amplification of the COI gene yielded DNA bands measuring 490 base pairs (bp), while homology and phylogeny analysis confirmed the morphological identification. Based on BLAST analysis, the similarity of COI genes of mealybugs in this study was above 99% with other P. jackbeardsleyi. The study specimen was identified as P. jackbeardsleyi on the seed rhizomes of C. aeruginosa by comparing the morphological features of insect specimens and results of the species available in GeneBank. This result represented the first documented report about the presence of the species in storage.

Sweet alyssum (Lobularia maritima L.) is known as an insectary plant with great potential in enhancing the occurrence and diversity of beneficial insects in different crops. However, agronomic aspects of the introduction of this plant are still not fully recognized. Field studies aimed at assessing entomological relationships in the quasi-coordinate system focused on evaluating the impact of sweet alyssum as a companion plant in broad bean (Vicia faba L.) cultivation on the prevalence of the black bean aphid (Aphis fabae Scop.) and its natural enemies. It was also sought to determine the optimal row spacing for broad beans when introducing an additional plant between the rows. A 3-year field experiment involved various row spacings for broad beans: 50 cm, 65 cm, and 80 cm, with a control group at a 50 cm row spacing representing conventional cultivation, and another group with standard chemical pest protection as a reference. The results indicated that using sweet alyssum as a companion plant significantly reduced the black bean aphid population. It was comparable to the effect of chemical pest control. This companion planting also considerably increased the population of natural enemies of the black bean aphid, including hoverfly eggs and larvae, as well as various stages of ladybirds, particularly the adult stage. Sweet alyssum contributed to a reduced aphid-to-predator ratio, leading to a significant decrease in black bean aphid numbers and an earlier colonization of aphids by hoverflies and ladybirds on broad bean plants. In summary, sweet alyssum has the potential to effectively decrease black bean aphid occurrences, particularly on ecological farms. Notably, sweet alyssum’s competitiveness with broad beans and the different row spacing had minimal impact on predator occurrence, eliminating the need to increase standard row spacing for this plant.

In Morocco, the sugar beet crop is severely harmed by the insect pest Cassida vittata Vill. which affects its yield quantity and quality. Chemical pesticides are considered the most common strategy to control this pest, and their use is extremely harmful to human health and the environment. In this context, the adults of C. vittata were exposed to five essential oils (EOs) obtained from: Artemisia herba alba Asso. (Asteraceae), Eucalyptus globulus Labill. (Myrtaceae), Mentha pulegium L. (Lamiaceae), Rosmarinus officinalis L. (Lamiaceae), and Shinus terebinthifolius Raddi. (Anacardiaciae). Their contact and fumigant activity was evaluated every 24 h for 3 days. Their repellent effect was tested by filter paper and sugar beet discs every 5 min for 30 min. Their antifeedant effect, via Relative Growth Rate (RGR), Relative Consumption Rate (RCR), Efficiency of Conversion of Ingested Food (ECI) and The Feeding Deterrence Index (FDI),was evaluated using three doses in each experiment. For the contact toxicity, M. pulegium, A. herba alba and R. officinalis showed the highest mortality rates with 100, 92 and 78%, respectively, after 24 h at 0.283 μl · cm^–2. For the fumigant toxicity, 100% mortality was observed at the highest concentration of M. pulegium after 24 h and from A. herba alba with 88 and 96 after 48 h and 72 h, respectively. Regard­ing the repellent effect by filter paper, the repellency of R. officinalis and A. herba alba was 82.92 and 57.85%, respectively. However, M. pulegium showed 63% of repellency after 5 min at 0.057 μl · cm^–2. In the antifeedant test, M. pulegium gave significant results in all nutritional indices. In conclusion, M. pulegium was the most effective in all tests used in this study. Our findings promote the use of these essential oils as efficient biocontrol compounds against the adults of C. vittata.

In light of the increasing world’s population and progressing climate changes, novel visions for agricultural practices are needed. In recent years nanofertilizers and elicitors have been investigated as methods to provide improved crop yield and quality. The potential of foliar application of iron nanofertilizers, elicitors (methyl jasmonate (MeJA) or methyl salicylate (MeSa)) and their combinations on the emission of volatile organic compounds (VOCs), have been evaluated for Brassica napus. The combined application of nanofertilizers and elicitors was found to result in an increase of VOC emissions by B. napus in comparison to their individual usage. The highest VOC emissions were observed at the time point 24 hours after the application of a 10 μg · ml^–1 concentration of nanofertilizers and MeJa. To our knowledge, this is the first time that combinations of nanofertilizers and elicitors have been applied to plants to determine their response on the emission of plant defense volatiles.

In the present eco-conscious era, consumers opt for food choices reflecting ethical and environmental concerns, which increases the demand for organic products. Biocontrol is a viable plant protection method in organic farming. Freeze-drying is a long-term preservation technique for microbial agents, ensuring their genetic stability and viability. To reduce freeze-drying-induced damage to their cells, cryoprotective agents like trehalose and monosodium glutamate are used. This study evaluated the impact of the addition of these substances during the freeze-drying process on chosen yeast isolates’ viability, their ability to survive on tomato leaves and maintain antagonistic properties against Botrytis cinerea Pers. Yeast isolates 114/73 (Wickerhamomyces anomalus E.C. Hansen) and 117/10 (Naganishia albidosimilis Vishniac & Kurtzman) were tested on tomato plants under greenhouse conditions before and after the freeze-drying process for both the ability to colonize leaves and as a preventive and interventional treatment against B. cinerea. Yeast viability post freeze-drying was evaluated in vitro. Both trehalose and monosodium glutamate increased yeast viability during the freeze-drying process. Viability was not very high (from 30.33 to 36.17% for 117/10 and from 10.67 to 16.5% for 114/73). Yeast dehydrated after freeze-drying, protected with trehalose and monosodium glutamate, displayed the same colony count on tomato leaves as before freeze-drying. The efficacy of protective treatments depended on the yeast isolate, the protective substance used during freeze-drying, treatment timing (prevention vs. intervention), and interactions of those factors. Cryopreserved isolate 117/10 performed better than 114/73 with the addition of either trehalose or monosodium glutamate, reducing the disease severity index from 88.3% (control) to 18.75−55.33%. Preventive treatments were more efficient than intervention. The leaf colonization ability and biocontrol efficacy of yeast isolates against B. cinerea post-freeze-drying offer promising solutions in sustainable agriculture. However, further research, to analyze the interactions between various factors and to optimize strategies may be needed.

This study was carried out to investigate the effect of different exposures of UV-C radiation (253.2 nm) (5, 10, 15, 20 and 25 mins) on the mortality of adult stages of four stored product pests: Sitophilus granarius L. (Coleoptera: Curculionidae) as a primary pest, Tribolium castaneum (Herbst) (Col.: Tenebrionidae), Cryptolestes ferrugineus (Stephens) (Col.: Laemophloeidae) and Oryzaephilus surinamensis (Ganglbauer) (Col.: Silvanidae) as secondary pests. Additionally, the viability of treated maize and wheat grains influenced by UV-C radiation (10 mins of UV-C at a distance of 22 cm) was analyzed by using a tetrazolium test. Insect rearing was carried out at 26 ± 2°C, 60 ± 7% RH, 16/8 photoperiod. Our results confirmed that a longer exposure (25 min.) to UV-C corresponded with higher mortality over time. In the elapsed time after radiation treatment as a function of exposure, the mortality was characterized by a power trend line for each examined insect species. S. granarius, as the primary stored product pest, in the crop treated by shorter exposure may prevent subsequent infestation of secondary stored product pests (T. castaneum, C. ferrugineus, O. surinamensis). The tetrazolium test showed that wheat seeds were more sensitive to UV-C radiation than maize seeds. This pest elimination technique is primarily recommended in environments exempted from viable stored seeds. UV-C irradiation of stored products could be an effective non-chemical practice against arthropod pests that move on the surface.

Barley cultivation faces challenges from changing climate conditions, including the increasing threat of drought. This study explored the potential of a fertilizer derived from Hermetia illucens L. frass to enhance the development and health of spring barley under optimal and drought conditions. The experiment, conducted in a controlled greenhouse environment, employed various fertilization treatments, including cattle manure and two doses of H. illucens L. frass-based fertilizer. Comprehensive assessments were made through visual observations and physiological measurements, including chlorophyll fluorescence, leaf gas exchange, and CO₂ exchange between the soil and the atmosphere. The results demonstrated that the application of H. illucens L. frass-based fertilizer significantly improved barley vigor and health compared to the control and cattle manure treatments, especially under drought stress. Physiological measurements revealed positive effects on chlorophyll fluorescence parameters, indicating enhanced photosynthetic efficiency. Leaf gas exchange parameters also reflected improved photosynthetic activity, with the H. illucens L. frass-treated plants outperforming others. This study provides valuable insights into the potential of insect-derived fertilizers, particularly H. illucens L. frass, as a sustainable and effective way to enhance crop resilience to drought. As climate change continues to pose challenges to agriculture, incorporating such novel fertilizers may offer a promising avenue for sustainable crop production.