Songqing Wu

BACKGROUND: Host‐egg preservation is a major bottleneck in the mass rearing of the egg‐parasitic mite Paracarophenax alternatus , a potential biological‐control resource targeting Monochamus alternatus , the principal vector of pine wilt disease in East Asia. Preserved host eggs must resist microbial deterioration while remaining suitable for mite acceptance, physogastric development and offspring production. This study aimed to develop a sequential preservation–compatibility framework integrating mold control with host‐use performance. RESULTS: A 15 min dipping window standardized exposure. Sorbic acid showed the most favorable mold‐control profile among single preservatives, and solvent–concentration optimization identified 1.6 g L ⁻¹ sorbic acid in 75% ethanol as the short‐cycle benchmark, combining no visible mold at 8 days with 100% selective parasitism and the highest physogastric‐female production among no‐mold formulations. In the 16 days validation assay, SA‐L3 (1.6 g L ⁻¹ sorbic acid plus 1.5 g L ⁻¹ lysozyme in 50% ethanol) maintained no visible mold through 12 days, reached 7.3% mold incidence at 16 days and had the lowest 4–16 days mold‐incidence area under curve (14.67% d). It retained full selective parasitism, benchmark‐level physogastric‐female production, high physogastric body volume and stable developmental duration. The host‐use index (HUI = 0.994), sensitivity analysis and principal component analysis consistently ranked SA‐L3 first. CONCLUSION: Host‐egg preservation for Paracarophenax alternatus cannot be optimized by mold control alone. Joint evaluation of microbial stability and host‐use performance identified SA‐L3 as the leading long‐cycle candidate under the tested laboratory conditions. This preservation–compatibility framework provides a quantitative basis for host‐substrate quality control in Paracarophenax alternatus mass rearing and related natural‐enemy production systems. © 2026 Society of Chemical Industry.

Pine wilt disease (PWD) is a devastating infectious disease of pine trees caused by the invasion of Bursaphelenchus xylophilus. Achieving rapid and accurate identification of pine trees in the early stages of infection is critical for preventing and controlling its spread, particularly for early warning and intervention before the plants exhibit obvious discoloration symptoms. The Plant Senescence Reflectance Index (PSRI) has shown significant potential for the early detection of PWD. However, existing studies often use its default band combinations for calculation, which may fail to fully exploit key wavelength information that is more sensitive to pre-symptomatic PWD stress. Based on unmanned aerial vehicle (UAV) hyperspectral imaging data, the present work systematically optimizes and reconstructs the three band parameters of the PSRI to explore an optimal wavelength combination more suitable for the early identification of PWD-infected trees. The results indicate that compared to the original settings of the PSRI, the wavelength combination of 490-666-700 nm performs better in pre-visually identifying infected pine trees in the early stages of infection, achieving a detection accuracy of 82.71%. Our work identifies an optimized PSRI wavelength combination more sensitive to the pre-visual early stage of PWD based on hyperspectral data. This method demonstrates promising potential for pre-visual detection of PWD before visible symptoms appear, which may provide an earlier opportunity for PWD monitoring and intervention.

Early detection of pine wilt disease (PWD) before visible crown discoloration is important for field inspection, confirmatory sampling, and timely management. However, because individual trees reach visible discoloration at different times, calendar-based analyses can blur the development of pre-visual spectral responses. Weekly UAV multispectral data from two Pinus massoniana forest sites were therefore aligned to the first visible crown discoloration of each tree. Crown-level band reflectance and vegetation indices (VIs) were examined from eight to one weeks before first visible discoloration, and healthy reference observations at each relative week were used to define 5th–95th percentile reference ranges for detection-rate (DR) analysis. Several VIs showed significant group-level differences from approximately seven weeks before first visible discoloration, whereas mean VI-based DR increased markedly to 0.52 at two weeks and 0.68 at one week before discoloration; single-band DRs were less stable. These results indicate a progressive pre-visual spectral response, with an exploratory early group-level indication emerging approximately seven weeks before discoloration and a stronger, more consistent spectral departure during the final two weeks. This onset-aligned framework provides a practical basis for scheduling repeated UAV surveillance and prioritizing field verification before obvious symptoms emerge.

This study evaluated the effects of pectinase, cellulase, and hemicellulase on dried roots of Litsea cubeba powder using enzyme-assisted hydrodistillation. Through single-factor experiment, four factors, namely, enzyme dosage, liquid-to-material ratio, enzymatic hydrolysis time and distillation time, have significant influence on the final yield of essential oil. The response surface experiment was designed by Box-Behnken design principle. The obtained model F regression value = 79.48, P < 0.0001, indicating that the model is extremely significant. Combined with actual use scenarios, the optimal extraction conditions are enzyme dosage 1000 U/g, liquid-to-material ratio 15:1, enzymatic hydrolysis time 3 h, distillation time 4 h, and the yield of essential oil is 0.403%. In addition, essential oil has certain antibacterial activity against Fusarium graminearum, and the EC50 value of essential oil is 78.266 μg/mL. Analysis of dry weight, relative conductivity, MDA content, SOD, CAT and POD activity of hyphae. The antibacterial mechanism of essential oil is related to the destruction of hyphae cell membrane, causing membrane lipid peroxidation reaction, affecting protective enzyme activity, etc.

BACKGROUND: Pine wilt disease, caused by the pinewood nematode ( Bursaphelenchus xylophilus ), poses a significant threat to pine trees. Therefore rapid and accurate molecular detection of B. xylophilus is particularly important for the prevention and control of pine wilt disease; however, traditional nematode DNA extraction methods are complex, time‐consuming and not suitable for on‐site sample collection. Hence, to overcome this limitation, we developed a practical applied diagnostic technology based on direct DNA extraction from pinewood strips. RESULTS: Through systematic optimization, the handheld ultrasonic disruptor was identified as the most effective tool for cell lysis, and increment borer sampling from the inner rings of infected pine trees yielded the highest detection accuracy. We confirmed that our method can extract DNA from B. xylophilus within 15 s using pinewood strips and that the obtained DNA can be directly used for polymerase chain reaction (PCR) amplification. Sensitivity tests confirmed that the method could detect a single nematode in spiked, artificially inoculated pinewood strips, while validation with 30 field‐collected pinewood samples achieved 100% consistency with traditional morphological identification. CONCLUSION: This 15‐s DNA extraction technique facilitates faster, simpler, and more cost‐effective diagnosis of pine wilt disease, offering a valuable tool for future disease management and control. © 2026 Society of Chemical Industry.

Understanding the early invasion and migration mechanisms of the pine wood nematode (PWN, Bursaphelenchus xylophilus) is crucial for disease control, but the dynamics immediately following inoculation remain unclear. Using histopathological observation (via paraffin sectioning and microscopy) in conjunction with a modified Baermann funnel technique, we investigated the initial stages of PWN invasion and migration across different stem types and wound types to delineate the precise migratory pathways. The results showed that cortical resin canals served as the sole pathway for initial PWN invasion; even low inoculation levels (10 to 100 nematodes) enabled PWN invasion through these canals within 1 h postinoculation (hpi). Optimal migration occurred in the bark of 2-year-old branches, reaching 15 cm (upward)/18 cm (downward) with approximately 11.7% of the inoculated nematodes by 12 hpi. Migration did not differ between natural beetle-feeding wounds and artificial wounds within 12 hpi. Migration through the xylem was severely limited (only 3 to 15 nematodes migrating 1 to 6 cm within 12 h) yet was notably accelerated when passing through branch cross-sections (17 cm in bark and 16 cm in xylem within 6 hpi) compared with the maximum distance (8 cm) observed in beetle-feeding wounds or artificial wounds. Furthermore, a critical invasion window was identified: wound exposure for ≤12 h permitted PWN invasion, whereas exposures of 16 or 24 h significantly reduced or completely prevented invasion. These results define the first 12 h post-wounding as the key vulnerability period for PWN infection, providing a critical timeframe for targeted prevention of pine wilt disease.

BACKGROUND: Pine wood nematode (PWN) is a major invasive species causing severe degradation of pine forest ecosystems. During PWN infection, pine trees undergo quantifiable physicochemical changes, including variations in pigment content and water status, which can effectively characterize tree health. Retrieving these indicators using remote sensing techniques therefore provides a promising approach for early PWN monitoring. In this study, nine UAV flight campaigns were conducted from June to September 2024, acquiring multispectral imagery at four flight altitudes (50, 100, 150 and 200 m). Field‐measured chlorophyll a (Chla), chlorophyll b (Chlb), carotenoids (Car) and water content (WC) data were integrated with UAV data to develop retrieval models based on 58 vegetation indices for estimating pigment content and water status of PWN‐infected Pinus massoniana . RESULTS: (1) Chla, Chlb and Car initially increased during the early infection stage (within the first 14 days) and subsequently declined, whereas WC exhibited a continuous decreasing trend; (2) significant spectral differences between PWN‐infected and control trees emerged in the red‐edge and near‐infrared bands at Day 14, earlier than ground‐based symptom observation; (3) WC retrieval achieved substantially higher accuracy than pigment‐related parameters, indicating that inversion‐derived WC could be more sensitive and effective in characterizing the health status of PWN‐infected trees; and (4) MR‐DSWI (Multiple Ratio Disease–Water Stress Index), Li5 and Guo4 consistently exhibited stable responses to both pigment and water status indicators across all flight altitudes. CONCLUSION: Overall, the robust performance of these indices highlights their strong general applicability for retrieving canopy pigment content and water status, providing reliable indicators for UAV‐based monitoring of PWN‐induced canopy degradation. © 2026 Society of Chemical Industry.

Monochamus alternatus larvae, as concealed trunk-boring pests, evade conventional insecticide contact due to their cryptic feeding niche. To overcome this limitation, previous studies have engineered strains of the naturally entomopathogenic bacterium Yersinia entomophaga. The lethality of these strains against M. alternatus was enhanced by incorporating extracellular secretion systems and enriching insecticidal proteins within the larval midgut. However, plasmid loss occurs during serial subculturing. Here, we established an engineered strain that expresses the red fluorescent protein gene mCherry to explore the applicability of bacterial conjugation transfer to Yersinia. We then constructed a chromosomally integrated strain (CSLH88-pCHSW) that incorporates extracellular secretion systems. The results of stability assays demonstrated 100% retention of the mCherry and Cry3Aa-T-HasA genes over 78 generations. SDS-PAGE and Western blot analyses confirmed the extracellular secretion of the Cry3Aa-T protein in the CSLH88-pCHSW strain. Bioassays revealed that the CSLH88-pCHSW strain was significantly more virulent against M. alternatus larvae than both the wild-type strain (CSLH88) and the plasmid-transformed strain (CSLH88-pCHKW), and exhibited markedly faster insecticidal kinetics. Our study reveals the application of bacterial conjugation transfer technology for constructing biocontrol strains. This genomically stabilized Yersinia strain eliminates the risks of failure associated with plasmid loss in the field, enabling the sustainable control of M. alternatus.