Search Results (78)

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 relative efficacy of amorphous silica dusts, malathion, and pirimiphos methyl was assessed against S. oryzae and T. castaneum in stored wheat under laboratory conditions. Insecticidal performance was influenced by physical properties such as particle size, surface area, bulk density, and oil/water adsorption capacity. Fumed silicas showed the highest toxicity, particularly Wacker HDK H20 (LC₅₀ = 19.4 mg/100 g at 12% moisture). Precipitated silica, Sipernat 22, though less potent (LC₅₀ = 46.6 mg/100 g), displayed consistent efficacy across different moisture levels, making it a suitable inert carrier. Increasing grain moisture to 15% significantly reduced the effectiveness of all dusts. When insecticides were combined with silica, their toxicity increased markedly. Malathion on silica (0.2%) reduced LC₅₀ values to 21.5 and 23.3 µg a.i./100 g for T. castaneum and S. oryzae, respectively, compared to 52.3 and 84.7 µg a.i./100 g on talc. Pirimiphos methyl on silica (0.1%) was the most effective, achieving LC₅₀ values of 13.4 and 15.5 µg a.i./100 g. Long-term bioassays over 25 weeks showed declining mortality rates, particularly at 15% moisture. However, pirimiphos methyl on silica maintained over 90% mortality at 12% moisture throughout the period, indicating strong residual efficacy. The results highlight the synergistic potential of combining silica with chemical insecticides and the crucial role of environmental humidity in stored grain pest management. 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

With over 1000 species of pests causing losses in both the quantity and quality of stored food, insect contamination poses significant challenges. The present study assesses the efficacy of the combination of λ-cyhalothrin and chlorantraniliprole against four key storage pests—Trogoderma granarium, Sitophilus oryzae, Rhyzopertha dominica, and Tribolium castaneum. Laboratory bioassays demonstrated species-dependent mortality, with S. oryzae and R. dominica suffering 100% mortality in several tested scenarios. A 90-day persistence trial revealed decreased efficacy over time, especially for T. granarium (32.0–71.4% at 0 days and 0.0–7.5% at 90 days) and T. castaneum (38.8–82.7% at 0 days and 0.0–12.7% at 90 days) vs. S. oryzae and R. dominica. Progeny production of S. oryzae and R. dominica was almost suppressed in persistence trials (0.4 individuals per vial and 1 individual per vial, respectively) after 30 days of storage at the dose of 5 mg/kg wheat. The results highlight the variability in insecticidal performance based on species, dose, exposure, and commodity type, emphasizing the need for tailored pest management strategies in the storage environment. Full article

Stored grain pests like Sitophilus oryzae pose significant challenges to food security and quality, necessitating eco-friendly pest management strategies. This study investigates the combined efficacy of reduced doses of diatomaceous earth (DE) and basil (Ocimum basilicum L.) essential oil (EO) as an alternative to conventional pesticides. Laboratory trials evaluated the effectiveness of the treatments—DE, EO, and a mixture of both (at halved doses)—against S. oryzae in wheat, alongside their impact on bread quality and sensory attributes. Results showed that DE and the DE + EO at halved doses combination achieved over 82% pest mortality, comparable to standard DE doses but with reduced mechanical and environmental drawbacks. EO alone demonstrated limited insecticidal activity. Bread made from treated wheat retained high sensory acceptability, with DE enhancing elasticity and crumb aroma. EO-enriched bread exhibited a complex aromatic profile due to methyl chavicol, though with reduced crumb elasticity and a slightly bitter aftertaste. Shelf-life assessments indicated that DE and DE + EO at halved doses extended mold-free storage by one day compared to untreated bread. These findings highlight the potential of combining DE and EO at reduced doses to manage stored grain pests sustainably, aligning with integrated pest management (IPM) and organic farming principles, while preserving the technological and sensory qualities of derived food products. 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

Sitophilus oryzae, Tribolium castaneum, Tribolium confusum, Oryzaephilus surinamensis, Rhyzopertha dominica, Tenebrio molitor, Trogoderma granarium, Acarus siro, and Alphitobius diaperinus represent significant arthropod stored-product pests worldwide. To combat these noxious arthropods, the current study examines the pesticidal effect of essential oils (EOs) derived from four aromatic plants, i.e., Illicium verum Hook. F., Citrus reticulata Blanco, Monodora myristica (Gaertn.) Dunal, and Xylopia aethiopica (Dunal) A. Rich. Considering the challenge of pesticide resistance, the current study focuses on assessing the efficacy of these EOs as an eco-friendly alternative to traditional synthetic insecticides. Two EO concentrations (500 and 1000 µL/kg wheat) were applied to different life stages of these pests in the bioassays. Mortality rates were monitored over several days under controlled environmental conditions. The findings demonstrated that C. reticulata and I. verum EOs had elevated insecticidal effects, especially against larval stages, resulting in 100% mortality in several species. On the contrary, M. myristica and X. aethiopica EOs showed less overall efficacy despite their potency against some pests. Both I. verum and C. reticulata EOs outperformed the positive control, pirimiphos-methyl, in several assays. The results of the current study highlight the potential of several EOs as effective alternatives in reducing synthetic pesticide use for integrated pest control management. 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

Phosphine (PH₃) has been widely used as a fumigant in food storage, but increasing PH₃ resistance in major pests makes finding alternative fumigants urgent. Methyl benzoate (MBe), a volatile organic compound regarded to be a food-safe natural product, has recently demonstrated significant toxicity against a variety of insect pests. This study is the first evaluation of the fumigation toxicity of three benzoate compounds, MBe, vinyl benzoate, and ethyl benzoate, against PH₃-susceptible and PH₃-resistant strains of Rhyzopertha dominica and Sitophilus oryzae. All strains were exposed to the compounds at concentrations up to 20 µL/1.5 L air for 24 h. Compared to vinyl benzoate and ethyl benzoate, MBe induced higher mortality rates in all strains at all concentrations. When food was made available, the lethal median concentration for MBe was 10–17-fold higher than when tested without food. Moreover, no significant differences were observed between the responses of the PH₃-susceptible and PH₃-resistant strains to the compounds. Notably, S. oryzae was more susceptible to MBe. In laboratory settings, MBe successfully controlled PH₃-resistant strains of R. dominica and S. oryzae, making it a viable option for PH₃-resistance management. Thus, MBe might be suitable for food security programs as an environmentally benign alternative fumigant. Full article

Chlorantraniliprole, an anthranilic diamide insecticide, has emerged as a promising solution for controlling agricultural pests because of its low mammalian toxicity and selectivity towards non-target organisms. This study investigated the sublethal effects of chlorantraniliprole on the mobility behavior of two significant stored-product pests, Sitophilus oryzae (L.) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Contact toxicity assays revealed varying susceptibility levels between the two species, with S. zeamais showing higher sensitivity. Subsequent analysis of mobility behavior, both in the presence and absence of food, indicated significant differences between chlorantraniliprole-exposed and control groups. While S. oryzae exhibited altered locomotion patterns and a decreased number of food approaches at sublethal concentrations, S. zeamais displayed increased walking time and reduced immobility periods. These findings highlight the importance of considering sublethal effects in understanding the overall impact of chlorantraniliprole on stored-product pests. Further research into the long-term consequences of sublethal exposure is warranted to inform more effective pest management strategies in storage. 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