Search Results (48)

Cutin, a natural polyester, has attracted attention as a precursor for bio-based materials mimicking plant cuticles, particularly in food packaging. Most studies focus on polycondensation of hydrolyzed cutin fractions or combining cutin hydrolysates with other components; however, cutin precipitation, conditions affecting it, and cutin isolate film properties, without addition of other filmogenic material, remain insufficiently understood. Owing to the pH-dependent solubility of cutin, which progressively decreases as pH is lowered from strongly alkaline to acidic conditions, this study investigates the influence of pH on cutin dispersion formation and characteristics, and evaluates the impact of these dispersion properties on the formation and performance of self-assembled cutin isolate films, with a view to developing films with improved water-barrier and moisture-resistance properties. The influence of three plasticizers, glycerol, propylene glycol, and polyethylene glycol 400, at two concentrations was also evaluated. Results demonstrated that pH is the primary factor influencing cutin isolate dispersion characteristics and film performance, with decreasing pH promoting cutin precipitation and particle aggregation, thereby inducing changes in film structure. The strongest effects were observed for swelling, solubility, and tensile strength, followed by water vapor permeability, elongation at break, and thickness. Plasticizer type mainly affected moisture content and significantly influenced permeability and thickness, while concentration of plasticizer primarily impacted permeability. Interactions between pH and plasticizer significantly influenced most properties. Films prepared from cutin dispersions at pH 6.5 and pH 5 with polyethylene glycol (10%) showed the best balance of mechanical and barrier properties. Additionally, films prepared from the cutin solutions at pH 12 with glycerol (20%) exhibited good mechanical performance and high solubility, suitable for specific applications. Full article

Leptolegnia chapmanii is an oomycete pathogen of mosquito larvae. We investigated whether nutritional factors promoting cyst germination in vitro are associated with early infection events and instar-specific susceptibility in Aedes aegypti. Cysts of the Brazilian isolate ARSEF 12829 germinated rapidly in soybean seed extract, sunflower seed extract and minimal medium supplemented with yeast extract, whereas basal minimal medium did not promote germination. In sunflower seed extract, germination increased significantly with incubation time; in minimal medium, germination at 24 h was much higher with ≥0.2% yeast extract than with 0.1%. In third-instar larvae, a few cysts attached to the cuticle during the first 30–60 min, with no external germ tubes observed. At 3 h, melanized hyphal structures were detected in the midgut, and histological sections showed germinated and ungerminated cysts in the endoperitrophic space, with hyphae crossing the peritrophic matrix and midgut epithelium toward the hemocoel. Mortality increased with cyst concentration and exposure time and decreased with larval instar. At 3.3 × 10³ cysts/mL, final mortality reached 100% in L1–L3 and 91.2% in L4 larvae. These results link rapid cyst germination with early midgut invasion and high larvicidal activity. Full article

The two-spotted spider mite, Tetranychus urticae, poses significant agricultural challenges due to its rapid population growth and high capacity for developing chemical resistance. This study evaluated the acaricidal activity of bacterial strain TAM1, isolated from naturally deceased mites in Taiwan. In bioassays, TAM1 caused over 90% adult mite mortality within 48 h. Infected mites showed symptoms of body darkening and deformation of the ventral abdominal crest lines. Enzymatic analysis confirmed significant chitinase and gelatinase activities. Whole genome sequence of TAM1 was acquired with a 5,066,903 bp circular chromosome (CP120954) and a 164,574 bp circular plasmid (CP120955). Refined functional profiling identified a sophisticated enzymatic arsenal including core chitin-active families (GH18, GH20, AA10) and 157 proteases, with a high prevalence of metallopeptidases that correlate with the detected gelatinase activities. Secretome analysis predicted 42 extracytoplasmic proteases primarily utilizing the Sec-dependent pathway, while the presence of multiple CBM50 modules suggests a potential for targeted substrate anchoring. These genomic insights provide a plausible molecular basis for the observed enzymatic potential and the localized ultrastructural disruption of the T. urticae cuticle. The alignment between phenotypic observations, microscopic evidence, enzymatic activities, and genomic data suggests that TAM1 utilizes synergistic, multi-target mechanisms to exert its acaricidal effects. Based on analyses of whole-genome sequence and 16S rRNA gene sequence, TAM1 was tentatively designated as a strain of Kosakonia sacchari. The bacterial strain reported here represents a promising microbial agent for integrated pest management (IPM) programs. Full article

The invasive plant Tithonia diversifolia is a promising source of botanical insecticides, yet the mechanisms by which its active compounds impair insect physiology remain incompletely characterized. This study investigated the effects of 6-methoxyluteolin (6-ML), a flavonoid isolated from T. diversifolia, on melanization and cuticle integrity in Spodoptera litura larvae. Cuticle melanization, mediated by tyrosinase-catalyzed oxidation of tyrosine-derived substrates, is essential for cuticle sclerotization and immune defense in insects. Whether 6-ML directly targets this pathway has not been previously examined at the biochemical and histological level. Tyrosinase activity and melanin content were measured across 3rd–6th-instar larvae exposed to a concentration gradient of 6-ML (1.625–100 μg/mL). Histological sections of 4th- and 5th-instar larvae were prepared by paraffin embedding and hematoxylin and eosin (H&E) staining. 6-ML significantly reduced tyrosinase activity and melanin content in a concentration-dependent manner across all instars examined. Histological analysis revealed progressive cuticle thinning and loss of pigmentation granules with increasing 6-ML concentration. These findings provide the first biochemical and histological evidence that 6-ML targets the melanization pathway in S. litura, supporting its potential as a melanization-inhibiting botanical insecticide. Full article

Bursaphelenchus rainulfi is a pine-associated, non-pathogenic nematode that serves as a motile comparative species for evaluating nematophagous fungi. We investigated the in vitro biocontrol activity of Purpureocillium takamizusanense strain PMEPF27, originally isolated from insect cadavers in Taiwan, against mixed motile stages of B. rainulfi. Identity of the fungus was confirmed by morphology and ITS/EF-1α sequencing. Nematodes were exposed in liquid suspension to PMEPF27 conidia, with sterile water as the negative control and fluopyram as the positive control. Mortality was monitored over 7 days, and scanning electron microscopy was used to observe fungus–nematode interactions. PMEPF27 caused significantly higher mortality than the water control, reaching ~80% by day 7, and showed surface disruption of nematode cuticles, although no direct spore penetration was observed. These findings expand the nematophagous profile of P. takamizusanense beyond egg and sedentary stages, validate B. rainulfi as a motile comparative species in pine-nematode bioassays, and highlight PMEPF27 as a promising candidate for biocontrol development. Full article

As sessile organisms, plants have developed strategies to cope with exposure to high radiation. The plant cuticle is located at the interface between the plant and the surrounding environment, thus acting as a first barrier that protects plants against environmental conditions, including solar radiation. The isolated cuticles displayed notable absorptance in the infrared spectral range which, according to Kirchhoff’s law of thermal radiation, equals the emission dissipation ability. Comparison among the different cuticles showed that a significant range of their reflectance, transmittance, and absorbance spectra match the spectral regions known as atmospheric windows, between 3–4 and 8–13 microns, located within the mid-infrared region (MIR). They allow energy to pass through into the outer space. These optical parameters varied between cuticles from different plant species and they were not a simple function of the cuticle’s thickness but the product of its specific composition in combination with its molecular arrangement. Full article

The management of Meloidogyne incognita often depends on chemical nematicides, which pose environmental and health risks. This study investigated the potential of bacterial strains isolated from uncultivated native soil as biocontrol agents and plant growth-promoting rhizobacteria (PGPR) in tomato plants artificially infected with this nematode. Fifteen strains were screened in vitro for nematicidal and ovicidal activity, and four promising strains (307, GB16, GB24, and GB29) were selected for greenhouse trials. All strains reduced the nematode reproduction factor and the number of nematodes/g of root. Strains 307 and GB24 showed the highest reductions, 61.39 and 57.24%, respectively. Despite some positive physiological trends, Bacillus spp. did not promote a significant increase in plant growth. Metabolomic analysis revealed that the strains produced a wide range of primary metabolites with potential nematicidal activity. All strains also secreted proteases and chitinases, enzymes linked to nematode cuticle degradation. Preliminary identification based on the 16S rRNA gene and phylogenetic analysis grouped the four strains into the Bacillus subtilis group (strains GB16, GB29 and 307) or Bacillus cereus group (strain GB24); however, genome sequencing will be required in future studies. Overall, strains 307 and GB24 demonstrated strong biocontrol potential, supporting their use as sustainable and complementary alternatives to chemical nematicides. Full article

Cutin is a natural plant polyester, a constituent of the cuticle that covers aerial plant surfaces. Following the trends of agricultural and food waste reduction and the growing demand for plant-derived nanomaterials, cutin was extracted from tomato peels, a by-product of tomato processing. Subsequently, dispersions of cutin particles in the nano- and colloidal size range were prepared by pH-dependent precipitation. Four types of the dispersions were obtained, i.e., dispersion from cutin extract—NP E dispersion, dispersions from a solution of different cutin isolates, dialyzed cutin isolate–NP D dispersion, washed cutin isolate–NP W dispersion, and standard cutin isolate–NP S dispersion. Cutin precipitation occurred at pH lower than 7 and cutin dispersions with final pH 3–7 were formed. Zeta potential, particle size, and recovery of four cutin dispersions were investigated. All types of cutin particles bear a negative charge which increases on pH increase from 3 to 7, resulting in decrease in cutin nanoparticle size upon pH increase. In addition to that, the influence of cutin solution concentration and storage time on cutin dispersion particle size was found to be mitigated at pH ≥ 6. Among four dispersions, NP S had the highest cutin nanoparticle recovery at all pHs investigated. Full article

Lipids play vital roles in insect physiology, functioning as energy reserves, membrane constituents, and cuticular protectants. However, few studies have examined the anatomical distribution of lipids in blood-feeding Diptera and compared the compositions of the cuticular and internal compartments. This study analyzes the qualitative and quantitative profiles of free fatty acids (FFAs) in the female Tabanus bovinus, a hematophagous horsefly species, across different anatomical regions, including the head, wings, legs, thorax, and abdomen. The surface and internal lipid fractions were isolated using petroleum ether/dichloromethane extraction followed by sonication. GC-MS revealed the presence of 21 FFAs, including 16 saturated (C7:0, C8:0, C9:0, C10:0, C11:0, C12:0, C13:0, C14:0, C15:0, C16:0, C17:0, C18:0, C19:0, C20:0, C22:0, C24:0) and five unsaturated (C16:1, C18:2, C18:1, C20:5, C20:4). The head and wings showed the highest concentrations of cuticular FFAs. At the same time, internal lipid stores were most prominent in the thorax and abdomen (but four times lower than in the head cuticle), reflecting their role in energy storage and reproduction. All cuticular and internal extracts were dominated by C16:0, C18:0, and C18:1. Notably, several FFAs were undetected in specific compartments: C10:0 from inside the head, C11:0 and C13:0 from inside all examined body parts, C19:0 was absent from inside the head, wings and legs, while C20:5 and C20:4 were absent from both the cuticular and internal lipid pools of the wings. Interestingly, our analysis of the cuticle on the thorax and abdomen together revealed that both C13:0 and C19:0 were present only on the dorsal side, i.e., absent from the ventral side. These absences suggest a selective lipid metabolism tailored to the functional and ecological demands of T. bovinus females. Our findings suggest that the absence of specific compounds from individual body parts may serve as an indicator of physiological specialization. This work provides new insights into lipid compartmentalization in Tabanidae and offers a framework for future comparative and ecological lipidomics studies in insects. Full article

Parasitic diseases constitute a significant challenge to global public health, with Strongyloides stercoralis ranking among the most prevalent and clinically significant parasites. The limitations of current nematocidal therapies highlight an urgent need for novel treatment strategies. In this study, the nematocidal activity of chalepensin and graveoline, two compounds isolated from Ruta chalepensis, was evaluated against larval and adult stages of Strongyloides venezuelensis (model for S. stercoralis). The in vitro efficacy of these compounds was assessed on third-stage infective larvae (L3) and adult parthenogenetic females at various time points, while cytotoxicity was determined using Vero cells to calculate selectivity indices (SI). Both compounds showed good antiparasitic activity, but chalepensin exhibited superior nematocidal activity compared to graveoline, with an LC₅₀ of 3.9 µg/mL and an SI of 990 for L3, and an LC₅₀ of 16.8 µg/mL and an SI of 200 for adult females at 72 h. Morphological analysis via scanning electron microscopy in adult females revealed that graveoline induced mostly cuticle detachment, while chalepensin caused protuberances across the parasite body. These findings suggest that both compounds possess promising antiparasitic potential, with chalepensin emerging as a particularly potent candidate for further exploration. Full article

The banana pseudostem weevil (BPW), Odoiporus longicollis (Oliver), is one of the most destructive pests of bananas that is seriously affecting the yield and quality of bananas. We isolated pathogens from banana pseudostem weevils in Xishuangbanna and Dongchuan, Yunnan, China, and explored their biological characteristics. The pathogenicity of the strains was verified through laboratory and greenhouse inoculation experiments. The results showed that four strains of fungi were identified and confirmed as Beauveria caledonica (Bc) via ITS-rDNA sequencing. Optimal in vitro culture conditions were found to be a photoperiod of 24 h light, 25 °C temperature, and 18 days on potato dextrose agar (PDA) medium with insect meal. Under these conditions, the Cs-1 strain achieved a colony diameter of 65.17 ± 0.74 mm and spore production of 1.24 × 10⁸ cfu/cm². The Cs-1 strain had the shortest lethal time (LT₅₀) of 9.36 days at an inoculum of 1.00 × 10⁹ cfu/mL, with a lethality of 86.67% after 20 days. The Cs-3 strain showed 77.78% lethality at 1.00 × 10⁸ cfu/mL after 20 days. Despite variations in virulence, lethality did not correlate with major cuticle-degrading enzymes. The Cs-3 strain demonstrated effective biocontrol in greenhouse tests. Banana plants suffered significant damage without Bc-treated BPW, while the treated plantlets thrived. The mortality rate reached 82.78% after 35 days. This study marks the first identification of these entomopathogenic fungi (EPF) in Yunnan, China, highlighting B. caledonica’s potential for biocontrol application. Full article

Gastrointestinal nematode infections significantly impact small ruminant production, causing substantial economic losses worldwide. The rising resistance to anthelmintics has led to the search for alternative treatments, including phytotherapeutic approaches. This study investigates the chemical composition and anthelmintic activity of crude extracts and fractions from Simarouba berteroana, an endemic plant from Hispaniola, against a multidrug-resistant isolate of Haemonchus contortus. Chemical analyses revealed high contents of phenolic compounds, tannins, and flavonoids and confirmed the presence of 22 quassinoids, 5 phytosterol lipids, 3 terpenoid quinones, 3 alkaloids, and 1 naphthoquinone. The hydroalcoholic and iso-butanol fractions showed the strongest egg hatching inhibition (IC₅₀ = 0.93 and 1.21 mg/mL, respectively), while hexane fractions were less effective (p < 0.05). Fluorescence microscopy showed that the extracts and fractions adhered to eggshells, causing evisceration and cuticle detachment in hatched larvae. All extracts, except for hexane fractions, inhibited larval exsheathment at 0.3 mg/mL, with phenolic compounds being responsible for this effect. These results provide the first evidence of the ovicidal and larval exsheathment inhibition activities of S. berteroana extracts and fractions against H. contortus, highlighting their potential in managing gastrointestinal nematodes in small ruminants. Further in vivo studies are needed to confirm these findings. Full article

Bursaphelenchus xylophilus is one of the most destructive quarantine pests, causing irreversible damage to pine trees. However, the unexpected identification of pine wilt disease in Northern China indicates that Bursaphelenchus xylophilus can survive under low temperatures. In this study, we analyzed the reproductivity variations among 18 different isolates, and SC13 was identified to have excellent low temperature resistance. Subsequent molecular analysis of SC13 indicated its distinct gene expression under low temperatures. The epidermal growth factor, nematode cuticle collagen and G-protein-coupled receptor genes with environmental adaptation functions were demonstrated to be differentially expressed under low temperatures. Meanwhile, morphological observations also indicated that SC13 contained significantly more lipid drops in low-temperature treatments. Generally, the identification of representative Bursaphelenchus xylophilus isolates will facilitate relevant studies in the future, and the discovery of the gene expression and morphological changes of Bursaphelenchus xylophilus under low temperatures could expand the current understanding of the environmental adaption abilities of such invasive nematodes. Full article

Waxy cuticle covers plant aerial organs and protects plants against environmental challenges. Although improved cuticle-associated traits are aimed at the wheat breeding programs, the mechanism governing wheat cuticular wax biosynthesis remains to be elucidated. Herein, wheat WW domain-containing protein TaCFL1 is characterized as a negative regulator of wax biosynthesis. The knockdown of TaCFL1 expression results in a 15% increase in wax accumulation and decreased leaf cuticle permeability in bread wheat. Furthermore, wheat class IV homeodomain transcription factors TaHDG1.1 and TaHDG1.2 are identified as partially redundant activators of wax biosynthesis. The silencing of TaHDG1.1 or TaHDG1.2 expression leads to an 11% reduction in epidermal wax accumulation and an increase in leaf cuticle permeability wax, while the co-silencing of TaHDG1.1 and TaHDG1.2 results in a 31% reduction in epidermal wax accumulation and a further increase in wax in the leaf cuticle permeability. Moreover, wheat 3-Ketoacyl-CoA synthase TaKCS10 is isolated as an essential component of the wax biosynthetic machinery. The silencing of TaKCS10 expression results in a 22% reduction in wax accumulation and increased leaf cuticle permeability. In addition, we demonstrated that the TaKCS10 expression is activated by TaHDG1.1 and TaHDG1.2, and that TaCFL1 attenuates the TaHDG1-mediated transcriptional activation of TaKCS10. This evidence supports that the WW domain-containing protein TaCFL1 negatively regulates wax biosynthesis via attenuating the transcriptional activation of the TaKCS10 gene mediated by HD-ZIP IV transcription factor TaHDG1. Full article

The Dubas bug is a serious and widespread pest of date palms in several countries in the Middle East. Chemical pesticides are widely used for managing this pest; however, most pesticides fail due to the continuous development of pesticide resistance. The primary goal of this research was to isolate endophytic fungi and test their entomopathogenic activity against Dubas bug nymphs and adults. A total of 27 fungal isolates were obtained and identified using the nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) region. These strains represent 16 species, belonging to 10 genera of seven different families, Ascomycota with six families and Basidiomycota with a single family, Quambalariaceae. Due to its remarkable biological control ability against insect pests, Clonostachys rosea was further studied for its entomopathogenic activity against Ommatissus lybicus nymphs and adults in comparison to a commercial strain of Beauveria bassiana. The concentration of 1 × 10⁸ conidia/mL of the selected endophytic isolate was used in lab experiments targeting Dubas bug healthy nymphs and adults. After 7 days of C. rosea treatment, the isolate caused significant mortality rates of 85% in the adult insects, while the mortality rates were moderate in the nymphs (33%). The commercial strain of B. bassiana resulted in 100% mortality levels in nymphs and adults of the Dubas bug. Scanning electron microscopy (SEM) of O. lybicus adults treated with C. rosea and B. bassiana showed mycelium growing on the eye, antenna, cuticle, and egg oviposition parts of O. lybicus. Mycelium growth of both fungi was also evident on the nymphs. This study reports for the first time the isolation of C. rosea from the Dubas bug, and its high entomopathogenic activity against an adult population of O. lybicus. Full article