Search Results (51)

Plant essential oils offer eco-friendly alternatives to insecticides, though their instability limits effectiveness. This study evaluated the physicochemical stability and fumigant efficacy of geranium (Pelargonium graveolens) oil nanoemulsion (GONE) versus bulk geranium oil (GOB) against Callosobruchus maculatus. Geranium oil nanoemulsions (GONEs) were prepared via spontaneous emulsification using 8% oil and varying surfactant levels. The 10% surfactant formulation produced the most uniform and stable nanoemulsion, with an average droplet size of 91.85 ± 0.02 nm and a low polydispersity index of 0.16 ± 0.02. No significant changes in droplet size were observed after 30 days of storage at room temperature and 9 °C, confirming the formulation’s stability. A fumigant bioassay was conducted using five concentrations (50, 100, 150, 200, and 250 µL/L air) of GOB and GONE over 24, 48, 72, and 96 h. Both forms exhibited concentration- and time-dependent toxicity against C. maculatus. Complete mortality was achieved sooner and at lower doses with GONE (72 h at 150 µL/L air versus 250 µL/L air for GOB; 96 h at 150 µL/L air for GONE versus 200 µL/L air for GOB). Geranium oil nanoemulsion consistently produced lower LC₅₀ and LC₉₀ values, indicating greater potency. It also significantly reduced progeny development. Residual fumigant bioassays at the LC₉₀ level showed that GONE retained efficacy against C. maculatus adults longer than GOB, causing 50% mortality 12 days post-treatment compared to 21% for GOB. Overall, nanoformulation enhanced the potency and persistence of geranium oil, highlighting its promise for protecting stored grains from C. maculatus. Full article

The cowpea weevil, Callosobruchus maculatus (F.), stands out as one of the most destructive field-to-storage pests of leguminous crops. This study investigates the potential of essential oils derived from two Satureja species, Satureja hortensis L. and Satureja khuzistanica Jamzad, for managing C. maculatus. Bioassay results revealed that both S. hortensis (72 h LC₅₀ = 0.20 µL/g) and S. khuzistanica (72 h LC₅₀ = 0.19 µL/g) essential oils exhibited significant toxicity against C. maculatus adults. The essential oils extended development time, reduced adult longevity, and decreased fecundity of the pest. Key population parameters, including intrinsic growth rate (r) and net reproductive rate (R₀), were significantly lowered, particularly by S. hortensis essential oil. Age-specific survival (l_x) and fecundity (m_x) rates were also declined in treated groups, with delayed reproductive peaks compared to controls. Chemical analyses of S. hortensis and S. khuzistanica essential oils indicated that carvacrol (30.9% and 62.9%, respectively), γ-terpinene (25.5% and 4.3%), p-cymene (9.7% and 7.9%), and thymol (3.7% and 9.3%) were the major components. Hierarchical cluster analysis (HCA) was carried out to compare and contrast the compositions with previous works. The results demonstrated that S. hortensis and S. khuzistanica essential oils, given their lethal and sublethal effects against C. maculatus, can be introduced as natural alternatives to hazardous chemical insecticides, highlighting the need for further research in this field. Full article

Cowpea, Vigna sp., is an important, low-cost protein source in subtropical and semi-arid regions, where seasonal rainfall makes storage necessary. However, the weevils Callosobruchus maculatus and C. chinensis cause significant grain losses during storage. While synthetic fumigants are commonly used to control these pests, their risks to mammals have prompted the search for safer alternatives. In this context, we tested palo santo, Bursera graveolens, essential oil with limonene, α-phellandrene, o-cymene and β-phellandrene, menthofuran, and germacrene-D as a sustainable approach. This plant is readily accessible, produces high fruit yields, and is used in households for various purposes. We evaluated the fumigant toxicity, repellency, and ovicidal effects of B. graveolens essential oil on both Callosobruchus species. Our results showed that B. graveolens oil was toxic to C. maculatus (LC₅₀ = 80.90 [76.91–85.10] µL) and C. chinensis (LC₅₀ = 63.9 [60.95–66.99] µL), with C. chinensis being more susceptible (SR = 1.27). Molecular docking analyses revealed that all the oil’s compounds bind to both the GABA and octopamine receptors, exhibiting high energy affinities; however, germacrene shows the strongest affinity in these receptors. C. chinensis was strongly repelled at all concentrations, while C. maculatus was repelled only at lethal concentrations. No ovicidal effect was observed in either species. In conclusion, our findings suggest that B. graveolens essential oil is a promising and sustainable protectant for stored cowpeas in small-scale storage units. Full article

The cowpea is a vital crop for low-resource farmers in the Sahel, but post-harvest losses due to insect pests remain a major challenge. Callosobruchus maculatus (Fabricius, 1775), is the primary pest responsible for most of the damage to stored cowpeas. Recently, Trogoderma granarium (Everts, 1898) was found infesting cowpeas in large warehouses in Niger. This study evaluated hermetic storage bags to manage both common and emerging insect pests. Treatments included (i) the Purdue Improved Crop Storage (PICS) hermetic bag; (ii) a woven polypropylene (PP) bag with a polyethylene (PE) liner and Phostoxin; and (iii) a woven PP bag without Phostoxin (control). Naturally infested cowpea grains were obtained from the Office des Produits Vivriers du Niger (OPVN) warehouse in Maradi, Niger. Infestation levels were assessed using 12 samples of 500 g each, randomly collected from each treatment at the start and end of the trial. Major pests identified were C. maculatus, T. granarium, and Tribolium sp., with initial populations of 0.83, 0.44, and 0.83 adults per 500 g of cowpea, respectively. After six months of storage, pest densities in the control increased significantly: 232-fold for C. maculatus, 7.4-fold for T. granarium, and 2.7-fold for Tribolium sp.; resulting in a 38.5% weight loss. In contrast, both the Phostoxin and the PICS hermetic bags effectively suppressed pest populations, preventing weight loss. This study confirms the efficacy of hermetic storage, such as the PICS bag, in protecting cowpeas from both common and emerging pests. Full article

Adult polyphenism is a prevalent form of adaptive evolution that enables insects to generate discrete phenotypes based on environmental factors. However, the morphology and molecular mechanisms underlying adult dimorphism in Callosobruchus maculatus (a global storage pest) remain elusive. Understanding these mechanisms is crucial for predicting the dispersal and population dynamics of C. maculatus. This knowledge can also provide a theoretical basis for biological control strategies. In this study, we compared the morphology of the hind wing and chest muscles, the transcriptional profiles, the energy metabolism substances, and the fecundity between the flight form and the normal form. The flight form displays a lighter overall appearance with small black spots, while the normal form lacks most flight muscles. Moreover, there are differences in the energy metabolism pathways between the two forms, including carbohydrate metabolism and oxidative phosphorylation. The flight form exhibits higher contents of carbohydrates, lipids, and mitochondrial energetic storage. The normal form exhibits better fertility but has lost its ability to fly. This is the first study to analyze the morphology and molecular characteristics of adult polyphenism in C. maculatus using morphological, physiological, and behavioral approaches, providing a foundational understanding of these aspects. Our study on C. maculatus also provides supporting evidence of a trade-off between dispersion and reproduction, where the flight form is capable of flying while the normal form has more reproductive benefits. Full article

Essential oils and their major compounds have been studied to protect stored grains, especially for the control of insects. In this context, this research aimed to investigate the fumigation and contact toxicities of the essential oil of Piper hispidinervum C. DC. (Piperaceae) (sin. Piper hispidum Sw.) to Callosobruchus maculatus adult individuals and the effect on insect progeny. We also assessed the essential oil’s effect on stored-cowpea quality. The fumigation bioassay used essential oil at 14.3, 57.1, 100.0, 142.9, and 185.7 µL/L of air, whereas the contact bioassay tested concentrations of 60, 80, 100, 120, and 140 µL/kg. Insect mortality was appraised after four days (fumigation) or one day (contact). In turn, oviposition and emergence rates were evaluated after seven (fumigation) or fifty (contact) days of storage. Grain quality was also analyzed after 50 days of storage. Safrole was confirmed as the primary compound of the essential oil. P. hispidinervum essential oil proved its fumigant and contact toxicities to C. maculatus adult individuals. The concentrations lethal to 50 and 95% of the population were, respectively, 91.23 and 242.59 µL/L of air (fumigation) and 101.51 and 208.52 µL/kg of cowpeas (contact). In both application forms, C. maculatus oviposition and progeny rates declined with the increase in the essential oil concentration. Furthermore, cowpea bean quality was preserved even at sublethal doses. Full article

Stored products, such as grains and processed foods, are susceptible to infestation by various insects. The early detection of insects in the supply chain is crucial, as introducing invasive pests to new environments may cause disproportionate harm. The STAR Center at Stevens Institute of Technology developed the Acoustic Stored Product Insect Detection System (A-SPIDS) to detect pests in stored products. The system, which comprises a sound-insulated container for product samples with a built-in internal array of piezoelectric sensors and additional electret microphones to record outside noise, was used to conduct numerous measurements of the vibroacoustic signatures of various insects, including the Callosobruchus maculatus, Tribolium confusum, and Tenebrio molitor, in different materials. A normalization method was implemented using the ambient noise of the sensors as a reference, to accommodate for the proprietary, non-calibrated sensors and allowing to set relative detection thresholds for unknown sensitivities. The normalized envelope of the filtered signals was used to characterize and compare the insect signals by estimating the Normalized Signal Pulse Amplitude (NSPA) and the Normalized Spectral Energy Level (NSEL). These parameters characterize the insect detection Signal Noise Ratio (SNR) for pulse-based detection (NSPA) and averaged energy-based detection (NSEL). These metrics provided an initial step towards the design of a reliable detection algorithm. In the conducted tests NSPA was significantly larger than NSEL. The NSPA reached 70 $\mathrm{d}$$\mathrm{B}$ for T. molitor in corn flakes. The insect signals were lower in flour where the averaged NSPA and NSEL values were around 40 dB and 11 $\mathrm{d}$$\mathrm{B}$ to 16 $\mathrm{d}$$\mathrm{B}$, respectively. Full article

An estimated 2000 plant species have been employed for pest control worldwide. The use of these botanical derivatives is thought to be one of the most cost-effective and sustainable options for pest management in stored grain. The present study was designed to assess the efficacy of five plant extracts viz; Nicotiana tabacum L., Nicotiana rustica L., Azadirachta indica A. Juss., Thuja orientalis L., and Melia azedarach L. against Callosobruchus maculatus L. Plant species extracts were applied at six different concentrations, i.e., 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0% in four replications. The phytochemical analyses of ethanolic extracts of five plant species showed variable amounts of phytochemicals i.e., alkaloids, flavonoids, saponins, diterpenes, phytosterol, and phenols. Total phenolic and flavonoid compounds were also observed. The efficacy of A. indica was highest, characterized by the lowest infestation rate (16.65%), host seed weight loss (7.85%), mean oviposition (84.54), and adult emergence (58.40%). In contrast, T. orientalis was found to be the least effective against C. maculatus, with the highest infestation rate of 25.60%, host seed weight loss of 26.73%, mean oviposition of 117.17, and adult emergence rate of 82.01%. Probit analysis was performed by estimating LC₅₀ and LC₉₀. The toxicity percentages of N. tabacum (LC₅₀ = 0.69%, LC₉₀ = 14.59%), N. rustica (LC₅₀ = 0.98%, LC₉₀ = 22.06%), and A. indica (LC₅₀ = 1.09%, LC₉₀ = 68.52%) were notable in terms of the lower LC₅₀ and LC₉₀ values after the 96-h exposure period against C. maculatus. Repellency was assessed by using the area preference and filter paper method. The repellency of C. maculatus on plant extracts increased with the increasing dose and time, such that it was the highest after 48 h. Likewise, at a 3% concentration, A. indica demonstrated 100.00% (Class-V) repellency followed by N. tabacum (96.00%, Class-V), N. rustica (74%, Class-IV), M. azedarach (70.00%, Class-IV), and T. orientalis (68.00%, Class-IV). Based on the findings of this study, we recommend integrating N. rustica, N. tabacum, A. indica, and M. azedarach for effective management of C. maculatus and highlight the potential of these plant species in the formulation of new biocidal agents. Full article

Morocco is a significant botanical reservoir that boasts a wealth of raw materials with promising applications across various industrial sectors, notably in pharmaceuticals and food. The objective of this study was to assess the effectiveness of essential oils (EOs) derived from Laurus nobilis L. leaves originating from the Tanger (EOT) and Meknes (EOM) regions in combating Callosobruchus maculatus infection. The chemical compositions of these oils were examined using Fourier transform infrared (FTIR) spectroscopy and gas chromatography–mass spectrometry (GC-MS). The biological activity of the EOs was evaluated via repulsion and fumigation tests against C. maculatus at varying concentrations. FTIR analysis revealed distinct vibrational bands indicative of various chemical compounds. GC-MS analysis was used to delineate the major chemical constituents of the EOs. The three predominant compounds in the EOT were 1,8-cineole (37.64%), linalool (16.40%), and adamantane (12.00%), whereas 1,8-cineole (47.84%), toluene (17.60%), and α-phellandrene (8.44%) were the most abundant in the EOM. Notably, the EOs exhibited significant repellent activity against C. maculatus, with repulsion percentages ranging from 51.11 to 90.00% in Tanger and 67.78 to 93.33% in Meknes. Mortality rates varied from 0 to 100% depending on the treatment. However, the mean concentrations showed mortality rates ranging from 29.44 to 65.56% for the EOT and from 21.11 to 67.78% for the EOM, with LD50 values of 11.96 μL/L and 5.22 μL/L. Docking studies revealed that 1,8-cineole had the highest binding affinity for the active site of acetylcholinesterase, thus confirming its toxic activity against C. maculatus. The findings of this study highlight the ability of EOs extracted from L. nobilis in the Moroccan regions of Tanger and Meknes to act as effective insecticides and repellents against C. maculatus, thereby highlighting avenues for further exploration of pest management and agricultural practices. Full article

Storage pests and the food spoilage they cause are problems of great concern. Using essential oil obtained from different plants as an insecticide against these storage pests can be considered an environmentally friendly pest management option. Lantana camara Linn. (family Verbenaceae) is a flowering species, and is also a noxious weed that can proliferate well in nearly all geographical habitats. A biopesticide derived from the essential oil extracted from this plant can offer an effective solution for controlling storage pests. The goal of this study is to extract and analyse the chemical composition of essential oil obtained from L. camara leaves, and assess its effectiveness as a bioactive substance against three storage pests: Tribolium castaneum, Lasioderma serricorne, and Callosobruchus chinensis. The yield of essential oil extracted from L. camara leaves was about 0.24 ± 0.014%. By employing the GC-MS technique, the major phytochemicals contained in L. camara leaf essential oil were identified as caryophyllene (69.96%), isoledene (12%), and ɑ-copaene (4.11%). The essential oil exhibited excellent fumigant toxicity (LC₅₀ of 16.70 mg/L air for T. castaneum, 4.141 mg/L air for L. serricorne and 6.245 mg/L air for C. chinensis at 24 h), contact toxicity (LC₅₀ of 8.93 mg/cm² for T. castaneum, 4.82 mg/cm² for L. serricorne and 6.24 mg/cm² for C. chinensis after 24 h) along with effective repellent activity towards the test insects. In addition, the oil showed no significant phytotoxicity on the germination of paddy seeds. This presents the potential to utilize a weed in developing a biopesticide for effectively managing stored product insects because of its strong bioactivity. Full article

Two bruchid species, Callosobruchus maculatus and Callosobruchus chinensis, are the most significant stored insect pests of tropical legume crops. Previously, we identified a major QTL, qBr6.1, controlling seed resistance to these bruchids in the cultivated zombi pea (Vigna vexillata) accession ‘TVNu 240’. In this study, we have narrowed down the qBr6.1 region and identified a candidate gene conferring this resistance. Fine mapping using F₂ and F_2:3 populations derived from a cross between TVNu 240 and TVNu 1623 (susceptible) revealed the existence of two tightly linked QTLs, designated qBr6.1-A and qBr6.1-B, within the qBr6.1. The QTLs qBr6.1-A and qBr6.1-B explained 37.46% and 10.63% of bruchid resistance variation, respectively. qBr6.1-A was mapped to a 28.24 kb region containing four genes, from which the gene VvTaXI encoding a xylanase inhibitor was selected as a candidate gene responsible for the resistance associated with the qBr6.1-A. Sequencing and sequence alignment of VvTaXI from TVNu 240 and TVNu 1623 revealed a 1-base-pair insertion/deletion and five single-nucleotide polymorphisms (SNPs) in the 5′ UTR and 11 SNPs in the exon. Alignment of the VvTAXI protein sequences showed five amino acid changes between the TVNu 240 and TVNu 1623 sequences. Altogether, these results demonstrated that the VvTaXI encoding xylanase inhibitor is the candidate gene conferring bruchid resistance in the zombi pea accession TVNu 240. The gene VvTaXI will be useful for the molecular breeding of bruchid resistance in the zombi pea. Full article

This study is aimed at evaluating the potential of the essential oil of Cinnamomum verum (EOCV) as an antioxidant, as an insecticide against Callosobruchus maculatus and for its anti-acetylcholinesterase activity. To this end, EOCV was extracted via hydrodistillation from this plant, and the identification of the phytochemicals was performed using gas chromatography–mass spectrometry (GC–MS). The antioxidant power was determined via in vitro tests, the insecticidal ability was tested via exposing C. maculatus to EOCV, and molecular docking was used to evaluate the anti-cholinesterase ability. The results of these GC–MS analyses show that the main composition of EOCV comprises Cinnamaldehyde dimethyl acetal (64.50%), cinnamicaldehyde (35.04%) and α-Copaene (0.11%). The insecticidal potential of the studied OEs, determined by using the inhalation test, and expressed as the concentration of EOs required for the death of 50% of the insects (LC50) and that required the death of 95% of adults (LC95) after 96 h of exposure, was 3.99 ± 0.40 and 14.91 ± 0.10 μL/L of air, respectively. In the contact test, 96 h of exposure gave an LC50 and LC95 of 3.17 ± 0.28 and 8.09 ± 0.05 μL/L of air, respectively. A comparison of the antioxidant activity of EOCV to that of ascorbic acid via DPPH free radical scavenging ability and Ferric Reducing Antioxidant Power (FRAP) revealed the IC50 and EC50 values of EOCV to be much higher than that obtained for ascorbic acid, and the molecular docking simulation revealed Coumarin, Piperonal, Cinnamaldehyde dimethyl and alpha-Copaene as possessing potential inhibitory activities against human acetylcholinesterase. However, further experimental validation is needed to enhance the prospects of this study. Full article

Pulses are a key source of dietary proteins in human nutrition. Despite several efforts to increase the production, various constraints, such as biotic and abiotic factors, threaten pulse production by various means. Bruchids (Callosobruchus spp.) are the serious issue of concern, particularly in storage conditions. Understanding host–plant resistance at morphological, biochemical and molecular levels is the best way to minimize yield losses. The 117 mungbean (Vigna radiata L. Wilczek) genotypes, including endemic wild relatives, were screened for resistance against Callosobruchus chinensis; among them, two genotypes, PRR 2008-2 and PRR 2008-2-sel, which belong to V. umbellata (Thumb.), were identified as highly resistant. The expression of antioxidants in susceptible and resistant genotypes revealed that the activity of phenylalanine ammonia lyase (PAL) was upregulated in the highly resistant wild Vigna species and lower in the cultivated susceptible genotypes, along with other biomarkers. Further, the SCoT-based genotyping revealed SCoT-30 (200 bp), SCoT-31 (1200 bp) and SCoT-32 (300 bp) as unique amplicons, which might be useful for developing the novel ricebean-based SCAR markers to accelerate the molecular breeding programme. Full article

Artemisia negrei (A. negrei) and Artemisia aragonensis (A. aragonensis) are in the family Asteraceae, which has been used in traditional medicine. The use of plant-derived insecticides has become a promising strategy to reduce the harmful effects of synthetic insecticides and overcome the bio-resistance of pest insects to insecticides. In this regard, the purpose of the current study was to determine the chemical composition and evaluate insecticidal effects of essential oils (EOs) extracted from A. negrei (EON) and A. aragonensis (EOA). Notably, all chemical constituents present in the EOs were identified through GC-MS analysis, whilst the insecticidal properties against Callosobruchus maculatus Fab. (C. maculatus) were investigated by use of in vitro an in silico approaches. The obtained results showed that both tested EOs present a significant insecticidal effect against C. maculatus, which increased significantly upon the dose used in both contact and inhalation tests. The lethal concentrations (LC₅₀) for the inhalation test were found to be 2.1 and 2.97 μL/L, while in the contact test they were 2.08 and 2.74 μL/L of air for EON and EOA, respectively. At 5 μL/L of air, the spawn reduction rate was 88.53 % and 77.41%, while the emergence reduction rate was 94.86% and 81.22% by EON and EOA, respectively. With increasing doses of up to 20 μL/L of air, the reduction in individual emergence reached 100% by the two oils tested after 36 h of treatment. In addition, Molecular docking (MD) simulations supported the in vitro findings and indicated that certain identified components in EOA and EON exhibited stronger hydrogen bonding interactions with the target receptors. Interestingly, the prediction of ADMET properties indicates that the molecules investigated have great pharmacokinetic profiles with no side effects. Taken together, our findings suggest that EOA and EON may exert both potential contact and inhalation insecticidal actions and could be used as an alternative tool for the control of this major insect pest of stored products. Full article

Nowadays, the modified atmosphere with ozone is one of the main alternatives for controlling insect pests in stored grains, as it allows grain quality to be maintained while causing no environmental damage. In light of this, the purpose of this study was to assess the toxicity of ozone to C. maculatus in cowpea grains as well as how it affects the physiological and physical properties of the grains. The toxicity was determined by estimating lethal doses (mg/g) at the top and bottom of the fumigation chamber for 50% and 95% of adult insects (LD₅₀ and LD₉₅). Cowpea grain samples were removed after being exposed to ozone, and the effect of ozonation on the physical and physiological quality of the grains was assessed. The electrical conductivity, water content, and germination were all examined in this manner. The lethal doses LD₅₀ were 65.97 and 45.52 mg/g when the insects were distributed at the top and bottom of the fumigation chamber, respectively. As a result, ozone toxicity was higher at the bottom than at the top. The increase in ozone doses resulted in a decrease in water content. The germination rate exceeded 90% in both locations where ozone was applied. The electrical conductivity remained constant, ranging between 152.01 and 239.59 S cm⁻¹ g ⁻¹. The findings indicate that ozone is toxic to C. maculatus but has no effect on grain quality. Ozone may therefore be used to manage C. maculatus in cowpea that has been stored. Full article