Search Results (54)

Invasive plant species are increasingly recognized not only as ecological threats but also as potential sources of bioactive compounds with agricultural applications. However, the combined allelopathic and insecticidal potential of Ailanthus altissima’s different plant parts remains insufficiently explored. This study evaluated the bioactivity of different plant part (leaf, bark, and branch) extracts of A. altissima. Secondary metabolites were characterized by HPLC–DAD–MS, while ethanol extracts (0.5–5%) were tested on wheat (Triticum aestivum) seed germination, seedling growth, oxidative status, and on the survival and repellency of the rice weevil (Sitophilus oryzae). Biological responses were strongly plant part and concentration-dependent. Leaf extracts contained the highest phenolic levels, dominated by caffeoylquinic acids and quercetin derivatives, whereas bark and branch extracts showed lower but compositionally distinct profiles. Despite this, bark and branch extracts produced the strongest biological effects, inhibiting germination energy and root growth at higher concentrations, while leaf extracts stimulated seedling performance, including increased vigor index, while in insect bioassays, bark and branch extracts caused higher mortality and stronger suppression of rice weevil populations. This study provides new evidence that biomass extracts of the invasive species A. altissima represent a promising source of biologically active compounds with both allelopathic and insecticidal properties, highlighting its potential valorization as a plant-based biopesticide for sustainable pest management. Full article

Recently, the occurrence of phosphine-resistant pests has been increasingly reported in many countries. In this study, the efficacy of carbonyl sulfide (COS) on phosphine-resistant and phosphine-susceptible strains of the rice weevil, Sitophilus oryzae, was evaluated to determine the applicability of COS as a fumigant to control phosphine resistance. S. oryzae at the egg, larval and adult stages was treated with phosphine and COS to determine the 50 and 99% lethal concentration time (LCt₅₀ and LCt₉₉, respectively) values. The LCt₅₀ values of phosphine for phosphine-susceptible S. oryzae at the egg, larval and adult stages were 1.44, 0.63, and 0.66 mg h/L, respectively, and those for phosphine-resistant S. oryzae were 30.65, 17.60, and 8.37 mg h/L, respectively. In contrast, the LCt₅₀ values of COS for phosphine-susceptible S. oryzae at the egg, larval, and adult stages were 284.19, 171.11 and 212.55 mg h/L, respectively, and those for phosphine-resistant S. oryzae were 289.78, 149.87 and 229.06 mg h/L, respectively. The COS-resistance ratios were 1.02, 0.88, and 1.08 for S. oryzae at the egg, larval, and adult stages, respectively. These results indicate that the efficacy of COS is similar for phosphine-susceptible and phosphine-resistant pests, suggesting that COS can be used to control phosphine-resistant grain pests. Full article

The rice weevil (Sitophilus oryzae) is a major pest in stored wheat, and traditional detection methods face challenges in identifying its hidden life stages within kernels. This study develops a nondestructive method to detect S. oryzae (Sitophilus oryzae) infestation in wheat kernels using hyperspectral imaging, spectral preprocessing, feature extraction, and classification modeling. Hyperspectral data were collected from wheat kernels at different infestation stages (1, 11, 21, and 25 days (d)) and from healthy kernels. Spectral quality was optimized using SG smoothing, multiplicative scatter correction (MSC), and standard normal variate transformation (SNV). Feature extraction algorithms, including Competitive Adaptive Re-weighting Algorithm (CARS), Successive Projection Algorithm (SPA), and Iterative Retention of Information Variables (IRIV), were used to reduce data dimensionality, while classification models like Decision Tree (DT), K-nearest neighbors (KNN), and Support Vector Machine (SVM) were applied. The results show that MSC preprocessing provides the best performance among the models. After feature band selection, the MSC-CARS-SVM model achieved the highest accuracy for the 1 day and 25 d samples (95.48% and 96.61%, respectively). For the 11 d and 21 d samples, the MSC-IRIV-SPA-SVM model achieved the best performance with accuracies of 94.35% and 94.92%, respectively. This study demonstrates that MSC effectively reduces spectral noise and improves classification performance. After feature selection, the model shows significant improvements in both accuracy and stability. The study confirms the feasibility of using hyperspectral technology to identify healthy and S. oryzae-infested wheat kernels, providing theoretical support for early, nondestructive pest detection. Full article

Cylas formicarius (Fabricius) is a major pest of sweet potato in Taiwan, where no microbial control agents are currently available. This study aimed to identify Beauveria bassiana strains with both high virulence and high spore productivity using a rice-based solid-state fermentation (SSF) system. Eleven field isolates were characterized using morphological traits and multilocus sequence analyses (Bloc, RPB1, RPB2, and TEF). Laboratory assays compared conidial production on 1/2 potato dextrose agar (PDA) and rice substrates and evaluated pathogenicity against adult C. formicarius by estimating median lethal time (LT₅₀) and the onset of mortality (t₀) based on cumulative mortality data. Substantial variation was observed among isolates in growth performance, sporulation, and virulence. Strain TyEf0054 consistently exhibited high pathogenicity, causing more than 80% mortality with conidia produced from both 1/2 PDA and rice, and showed rapid killing activity, with LT₅₀ values of approximately 5.5–5.9 days and t₀ values ranging from 3.55 to 3.99 days. In contrast, some strains exhibited high sporulation and virulence on 1/2 PDA but failed to produce conidia or showed severe clumping during rice-based solid-state fermentation, indicating poor suitability for large-scale production. These results demonstrate that high laboratory virulence alone is insufficient for strain selection and highlight the importance of integrating killing speed, final mortality, and SSF compatibility as joint selection criteria. Overall, TyEf0054 represents a promising locally adapted candidate for the development of commercial mycoinsecticides for sustainable management of sweet potato weevil in Taiwan. Full article

The gut microbiota of insects plays a fundamental role in modulating host physiology, including nutrition, development, and adaptability to environmental challenges. The rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is a major invasive pest of rice worldwide, yet the composition and functional profile of its gut microbial community remain poorly characterized. Here, we employed metagenome sequencing on the Illumina NovaSeq X Plus platform to explore the gut microbial diversity and predicted functions in adults of L. oryzophilus. Our results revealed a rich microbial community, comprising 26 phyla, 42 classes, 72 orders, 111 families, and 191 genera. The bacterial microbiota was overwhelmingly dominated by the phylum Proteobacteria (85.13% of total abundance). At the genus level, Pantoea (48.86%) was the most predominant taxon, followed by Wolbachia (14.57%) and Rickettsia (11.81%). KEGG analysis suggested that the gut microbiota is primarily associated with metabolic pathways such as membrane transport, carbohydrate and amino acid metabolism, cofactor and vitamin metabolism, energy metabolism, and signal transduction. eggNOG annotation further highlighted significant gene representation in amino acid and carbohydrate transport and metabolism, while CAZy annotation revealed glycosyl transferases (GTs) and glycoside hydrolases (GHs) as the dominant carbohydrate-active enzymes. This study provides the first comprehensive insight into the gut microbiome of L. oryzophilus adults, highlighting its potential role in the ecological success of this invasive pest. Our findings lay groundwork for future research aimed at developing novel microbial-based strategies for the sustainable management of L. oryzophilus. Full article

In the face of the global climate and ecological crisis, as well as growing consumer needs and demands, a transformation of the global food production and distribution system is necessary. The productivity and quality characteristics of Tritordeum make this cereal an effective tool in the sustainable modernization of the agricultural sector. However, this potential can be significantly limited in the supply chain by storage pests. This study aimed to assess the impact of Tritordeum resistance on the rice weevil (Sitophilus oryzae L.). The experiment used 11 Tritordeum breeding lines in comparison to three cereal species derived from conventional cultivation systems (common wheat Triticum aestivum L., durum wheat Triticum durum Desf., spring barley Hordeum vulgare L.). The research showed that Tritordeum may be a substrate on which S. oryzae feeds, although the intensity of the pest’s development varied depending on the line. The study also demonstrated that the hardness of the Tritordeum seed coat did not directly influence the development intensity of the analyzed beetles. It was noted, however, that the degree of infestation by these insects depended on the chemical profile of the infested kernels. The increased total protein content and lower fiber content (compared to common wheat) likely influence the development of Tritordeum resistance. This study demonstrates that Tritordeum possesses inherent resistance traits linked to its grain chemistry, providing a basis for breeding more storage-resistant cereal cultivars. Full article

The integration of essential oils (EOs) with biological control agents offers a promising alternative to synthetic pesticides, though compatibility remains unclear. This study evaluated nutmeg (Myristica fragrans, NM), cinnamon (Cinnamomum verum, CIN), and clove (Syzygium aromaticum, CL) specifically on S. oryzae and L. distinguendus. Olfactory and behavioral responses to whole EOs and major constituents (myristicin, cinnamaldehyde, eugenol) were analyzed using the area preference method (APM) and two-choice behavioral bioassay (TCB), with confirmation by gas chromatography–mass spectrometry (GC-MS). In S. oryzae, APM showed attraction to all three EOs (PI = 0.14 to 0.56). A paradox emerged, however, as single constituents were mostly repellent (eugenol: PI = −0.58 to −0.70; cinnamaldehyde: PI shifted from 0.16 to −0.20), underscoring the complexity of EO mixtures where multiple compounds act jointly rather than individually. In contrast, L. distinguendus strongly avoided CL and CIN in TCB, with fewer than 30% of parasitoids choosing the EO-treated side (χ² test, p < 0.05). CIN therefore demonstrated selective potential, simultaneously attracting S. oryzae while repelling L. distinguendus. These findings highlight the dual role of EOs as botanical pest control tools, while stressing the need to consider non-target effects before practical application. Full article

Rice (Oryza sativa L.) is a staple food globally, providing a critical food for the majority of the Asian population. However, it exposes risks during post-harvest storage, threatening substantial losses in rice quality and quantity. Hence, this study developed a cinnamon oil–chitosan:gelatin film (CO–C:G film) with the parameters as the chitosan:gelatin ratio (C:G = 1:1 and 1:2), cinnamon oil (CO) contents (0.75, 1.0, 1.25, 2.5, and 5.0%) and thickness film levels (0.165, 0.183, and 0.287 mm) to inhibit three fungal species, Rhizopus oryzae 01, R. microsporus 01, and Syncephalastrum racemosum 01, and control rice weevil infestation on paddy rice at a variety of water activities, such as 0.71 a_w and 0.95 a_w, at room temperature. The results revealed that at 0.95 a_w, the fungal growth rate and rice weevil’s mortality were impacted significantly by all parameters of the CO–C:G film (p < 0.05). Especially, the CO–C:G film with 1.25% CO and C:G = 1:1 at a thickness film of 0.287 mm inhibited all observed fungi and rice weevils better than the CO–C:G film’s other parameters. The inhibition of the CO–C:G film for these fungi ranged from 66% to 72.6%. Likewise, 80–100% of rice weevils were mortal when paddy rice was treated with the CO–C:G film on the 12th or 15th day of treatment depending on the water activity of paddy rice grains. The findings of this study provide insights for researchers, agricultural experts, and the food industry, highlighting the need to establish effective and sustainable strategies for rice preservation. Full article

Chlorobenzene is an industrial chemical with relatively high vapor pressure and has been used in the past to produce pesticide DDT (Dichlorodiphenyltrichloroethane). In this study, chlorobenzene was demonstrated to be an effective fumigant against two stored product insects: the confused flour beetle (Tribolium confusum) and rice weevil (Sitophilus oryzae). In small-scale fumigations in 1.9 L glass jars, the complete control of adults of both the confused flour beetle and rice weevil was achieved in 24 h at a dose of 150 μL/L at 21 °C. LC₉₅ values of chlorobenzene vapor concentration for adults of the confused flour beetle and rice weevil were estimated to be 1121 and 1114 ppm, respectively. In large-scale fumigations in a 60 L chamber, all life stages of the confused flour beetle and rice weevil in 20 kg of corn were fumigated for 24 h with 30 mL (500 μL/L) chlorobenzene at 21 °C. The complete control of adults and immature stages of the confused flour beetle was achieved. For the rice weevil, adults had 100% mortality, and immature life stages had 97.8% mortality. These results demonstrated that chlorobenzene is effective as a fumigant against stored product insects, and it is technically feasible to conduct large-scale fumigations for postharvest pest control on stored products. Full article

Floor traps were placed in a feed mill in Greece for a period of approx. 13 months to illustrate the relative abundance and distribution of the stored product insects found. More than 20 taxa were found, with most of them belonging to Coleoptera. The most abundant species found were the rice weevil, Sitophilus oryzae (L.), and the granary weevil, Sitophilus granarius (L.), which are common primary colonizers of grains, and the confused flour beetle, Tribolium confusum Jacquelin du Val, and the red flour beetle, Tribolium castaneum (Herbst), which are secondary colonizers that usually occur in processed amylaceous commodities. Interestingly, the highest population densities of all four species were recorded during the same period, with the secondary colonizers slightly preceding the primary colonizers. Although competition among these species has been recorded in previous studies, we found that these four species could coexist during the entire trapping period in the same sampling units, which indicates possible spatial segregation and different colonization patterns in space and time. Our results demonstrate that trapping in storage and processing facilities is an essential component of decision-making regarding stored product pest management strategies in localized applications, and can drastically reduce the need for treating the entire facility. Full article

The rice weevil, Sitophilus oryzae (L.), is a major pest that poses a considerable threat to grain safety storage. Early detection is of great significance in reducing grain losses. Studies have demonstrated that pest infestation causes alterations in grain volatiles, potentially indicating the presence of pests. In this study, we detected volatile organic compounds (VOCs) in non-infected and pest-infected wheat on the 3rd, 9th, 17th, 22nd, and 40th days, corresponding to the developmental stages of the rice weevil at the egg, young larval, old larval, pupal, and adult stages, respectively. A total of 126 VOCs were identified, including 96 hydrocarbons, 7 alcohols, 5 aldehydes, 9 ketones, 9 esters, and 18 other compounds, 62 of which are newly produced compared to non-infected wheat. Six characteristic volatiles, namely dodecane, pentadecane, hexadecane, heptadecane, 2, 6, 10-trimethylpentadecane, and squalene, may be related to the degradation of lipids and the expression of wheat stress tolerance and underwent significant changes as infestation progressed, according to the VIP value. This study assists in interpreting the effects of rice weevil infestation on wheat at the metabolic level and establishes a foundation for storage inspection based on VOC analysis. Full article

The essential oil and the aqueous and ethanolic extracts obtained from the aerial parts of Pelargonium graveolens cultivated in Morocco were studied for their antioxidant and insecticidal activity against rice weevils (Sitophylus oryzae). The total phenolic content of the extracts was determined by a spectrophotometric method and the phenolic compounds were extensively characterized by HPLC-PDA/ESI-MS. To evaluate antioxidant potential, three in vitro assays were used. In the DPPH test, the ethanolic extract was the most active, followed by the aqueous extract and the essential oil. In the reducing power assay, excellent activity was highlighted for both extracts, while in the Fe²⁺ chelating activity assay, weak activity was observed for both the essential oil and the ethanolic extract and no activity for the aqueous extract. Concerning insecticide activity, the toxicity of the essential oil and the extracts was tested against rice weevils; the lethal concentrations LC₅₀ and LC₉₉ were determined, as well as the lethal time required for the death of 50% (LT₅₀) and 99% (LT₉₉) of the weevils. The essential oil had the highest activity; 100% mortality of S. oryzae was observed around 5, 9, and 8 days for the essential oil and the aqueous and ethanolic extracts, respectively. Full article

The traditional manual sampling method for detecting stored grain insect pests is labor-intensive and time-consuming, often yielding non-representative samples. However, to achieve more accurate monitoring, it is necessary to understand the distribution patterns of different insect pests within grain silo and their correlation with monitoring and sampling data. This study aimed to assess the population density and distribution of Sitophilus oryzae (rice weevil) in bulk wheat grain to predict insect dynamics effectively. Utilizing a probe trap in a wheat silo, adult insects were tracked across different population densities. The traps recorded captured pests, alongside temperature and humidity data. The correlation analysis revealed that rice weevils were active throughout the silo but less prevalent at the bottom, with the highest distribution near the upper surface. Temperature and humidity significantly influenced their activity, particularly within the 22 °C to 32 °C range. Higher population densities correlated with increased relative humidity, impacting weevil activity. Trapping data aligned with overall population density changes in the silo. This study will provide an accurate assessment of the population density of adult rice weevils in grain silos based on temperature changes in the upper part of the grain silo. Full article

There is a high interest in utilizing natural bioactive products derived from plants as a substitute for synthetic chemicals in the industry. This research focuses on the phytochemical composition of essential oils (EOs) of Ammi visnaga L. and Trachyspermum ammi L and their insecticidal activity against Sitophilus oryzae (L.), a common pest found in stored cereals. The EOs were extracted through steam distillation and analyzed using gas chromatography coupled with mass spectrometry (GC-MS). The EOs of A. visnaga consisted of twenty-four components, with Abietadiene (41.23%) being the most abundant, followed by linalool (25.54%) and limonene (19.04%). On the other hand, the EOs of T. ammi consisted of twenty-eight main components, with isothymol being the most abundant (51.88%). The results revealed that the EOs of T. Ammi (DL₅₀ = 0.1 µL EOs/L of air) were more toxic than A. visnaga (0.38 µL EOs/L of air), with the toxicity varying based on doses and exposure periods. To further understand the molecular mechanisms underlying this activity, molecular docking and dynamic simulations were performed using the major chemical constituents of the oils. The simulation results indicated that the major compounds, Abietadiene and isothymol, interact with the catalytic sites of the target proteins, inhibiting acetylcholinesterase and chitin synthase. These interactions form energetically favorable systems that remain stable throughout the molecular dynamic period. This research provides valuable insights into the potential of these EOs as natural insecticides and highlights the importance of molecular modeling in understanding the biological activities of plant-derived compounds. Full article

In this study, bacteria residing in the gut of the rice weevils (Sitophilus oryzae L.) (Coleoptera: Curculionidae) feeding on aflatoxin-contaminated corn kernels were isolated and evaluated for their ability to suppress Aspergillus flavus and to remove/degrade aflatoxin B1 (AFB1). Four morphologically distinct S. oryzae gut-associated bacterial isolates were isolated and identified as Bacillus subtilis (RWGB1), Bacillus oceanisediminis (RWGB2), Bacillus firmus (RWGB3), and Pseudomonas aeruginosa (RWGB4) based on 16S rRNA gene sequence analysis. These bacterial isolates inhibited A. flavus growth in the dual culture assay and induced morphological deformities in the fungal hyphae, as confirmed by scanning electron microscopy. All four bacterial isolates were capable of removing AFB1 from the nutrient broth medium. In addition, culture supernatants of these bacterial isolates degraded AFB1, and the degradation of toxin molecules was confirmed by liquid chromatography-mass spectrometry. The bacterial isolates, B. subtilis RWGB1, B. oceanisediminis RWGB2, and P. aeruginosa RWGB4, were capable of producing antifungal volatile organic compounds that inhibited A. flavus growth. These results suggest that the bacterial isolates from S. oryzae gut have the potential to bind and/or degrade AFB1. Further research on their application in the food and feed industries could enhance the safety of food and feed production. Full article