Given the increasing demand for fruit safety assurance and environmental protection, plant essential oils have gained significant attention as natural alternatives for control of postharvest decay caused by various pathogens. In postharvest management, it is particularly important to effectively control postharvest decay without compromising the quality attributes of fruits. Although oregano essential oil (OEO) has been extensively studied for its antimicrobial properties against various postharvest pathogens, few studies have focused on its interactions with postharvest fruits. In this study, OEO was applied for management of postharvest decay of Pyrus sinkiangensis caused by Penicillium expansum, and its antifungal mechanisms and impacts on the quality attributes of pears were investigated. The OEO exhibited notable inhibitory effects, with determined MIC (0.02%) and MFC (0.04%) against P. expansum, which highlighted its potential as a viable alternative to synthetic fungicides. Our findings revealed that OEO disrupted P. expansum by compromising the integrity of the fungal plasma membrane, as evidenced by changes in plasma membrane permeability and the leakage of cellular components. The OEO treatment significantly reduced weight loss, maintained firmness, and preserved soluble-solid content in the treated pears. In addition, OEO treatment stimulated the intrinsic antioxidant mechanisms of pears, as demonstrated by elevated activities of superoxide dismutase and catalase during storage. This study provides compelling evidence for the antifungal and quality-preserving properties of OEO in the postharvest management of pears, underscoring its potential as an alternative to synthetic fungicides for controlling postharvest decay. The elucidation of the interaction between OEO and P. sinkiangensis would greatly enhance our comprehensive understanding of the biological activities of OEO and facilitate its practical application in the postharvest management of pears.

X-ray irradiation and modified atmospheres (MAs) provide eco-friendly, chemical-free methods for pest management. Although a low-oxygen atmospheric treatment improves the performance of some irradiated insects, its influence on the irradiation of quarantine insects and its impacts on pest control efficacy have yet to be investigated. Based on bioassay results, this study employed direct immersion solid-phase microextraction (DI-SPME) combined with gas chromatography-mass spectrometry (GC-MS) to determine metabolic profiles of late third-instar B. dorsalis larvae under normoxia (CON, Air), hypoxia (95% N₂ + 5% O₂, HY), super-hypoxia (99.5% N₂ + 0.5% O₂, Sup-HY), irradiation-alone (116 Gy, IR-alone), hypoxia + irradiation (HY + IR) and super-hypoxia + irradiation (Sup-HY + IR). Our findings reveal that, compared to the IR-alone group, the IR treatment under HY and Sup-HY (HY + IR and Sup-HY + IR) increases the larval pupation of B. dorsalis, and weakens the delaying effect of IR on the larval developmental stage. However, these 3 groups further hinder adult emergence under the phytosanitary IR dose of 116 Gy. Moreover, all IR-treated groups, including IR-alone, HY + IR, and Sup-HY + IR, lead to insect death as a coarctate larvae or pupae. Pathway analysis identified changed metabolic pathways across treatment groups. Specifically, changes in lipid metabolism-related pathways were observed: 3 in HY vs. CON, 2 in Sup-HY vs. CON, and 5 each in IR-alone vs. CON, HY + IR vs. CON, and Sup-HY + IR vs. CON. The treatments of IR-alone, HY + IR, and Sup-HY + IR induce comparable modifications in metabolic pathways. However, in the HY + IR, and Sup-HY + IR groups, the third-instar larvae of B. dorsalis demonstrate significantly fewer changes. Our research suggests that a low-oxygen environment (HY and Sup-HY) might enhance the radiation tolerance in B. dorsalis larvae by stabilizing lipid metabolism pathways at biologically feasible levels. Additionally, our findings indicate that the current phytosanitary IR dose contributes to the effective management of B. dorsalis, without being influenced by radioprotective effects. These results hold significant importance for understanding the biological effects of radiation on B. dorsalis and for developing IR-specific regulatory guidelines under MA environments.

The management of phosphine (PH3) resistance in stored grain pests is an essential component of implementing timely and effective pest control strategies. The prevailing standard method for PH3 resistance testing involves the exposure of adult insects to a specific concentration over a fixed period. Although it is widely adopted, this method necessitates an extensive period for assay preparation and diagnosis. To address this issue, this study employed Direct Immersion Solid-Phase Microextraction (DI-SPME) coupled with Gas Chromatography-Mass Spectrometry (GC-MS) to compare and analyze the metabolic profiles of PH3-sensitive (TC-S), PH3 weak-resistant (TC-W), and PH3 strong-resistant (TC-SR) Tribolium castaneum (Herbst) adults. A total of 36 metabolites were identified from 3 different PH3-resistant strains of T. castaneum; 29 metabolites were found to present significant differences (p < 0.05) across these groups, with hydrocarbon and aromatic compounds being particularly prevalent. Seven metabolites showed no significant variations among the strains, consisting of four hydrocarbon compounds, two iodo-hydrocarbon compounds, and one alcohol compound. Further multivariate statistical analysis revealed a total of three, two, and nine differentially regulated metabolites between the TC-S versus TC-W, TC-S versus TC-SR, and TC-W versus TC-SR groups, respectively. Primarily, these metabolites comprised hydrocarbons and iodo-hydrocarbons, with the majority being associated with insect cuticle metabolism. This study demonstrates that DI-SPME technology is an effective method for studying differentially expressed metabolites in T. castaneum with different levels of PH3 resistance. This approach may help to provide a better understanding of the development of insect PH3 resistance and act as a valuable reference for the establishment of rapid diagnostic techniques for insect PH3 resistance.

In response to the growing need for sustainable and safe postharvest strategies, plant essential oils have emerged as promising natural alternatives to synthetic fungicides. Mango (Mangifera indica L.), as a vital tropical fruit, suffers significant postharvest losses due to anthracnose caused by Colletotrichum gloeosporioides. This study investigated the antifungal efficacy of oregano essential oil (OEO) against C. gloeosporioides and its regulatory effects on the postharvest quality of mango fruit. The potent antifungal activity of OEO is demonstrated by its low MIC (0.005%) and MFC (0.01%) against C. gloeosporioides. The antifungal mechanism was primarily attributed to the disruption of plasma membrane integrity of C. gloeosporioides, as indicated by increased propidium iodide uptake, elevated extracellular conductivity, and leakage of cellular proteins. The OEO treatment inhibited peel color transformation, reduced weight loss, maintained firmness, and slowed the increase in the soluble solids content to acidity ratio. Furthermore, OEO enhanced the fruit’s antioxidant capacity by sustaining higher superoxide dismutase activity and suppressing the activities of polyphenol oxidase and peroxidase, leading to a marked reduction in malondialdehyde accumulation. These findings comprehensively demonstrate the dual functionality of OEO as a direct fungicidal agent and a systemic physiological regulator that delays senescence and preserves mango quality. This study underscores the potential of OEO as a sustainable alternative for integrated postharvest management of mango anthracnose, offering insights for its practical application in the fruit industry.