Pimpinella anisum essential oil nanoemulsions against Tribolium castaneum-insecticidal activity and mode of action

Essential oil nanoemulsion: An emerging eco-friendly strategy towards mosquito control

Mosquito borne diseases are impeding to human health due to their uncontrolled proliferation. Various commercial insecticides currently used become ineffective due to the resistance acquired by mosquitoes. It is necessary and a priority to combat mosquito population. Plant-based products are gaining interest over the past few decades due to their environment friendliness and their effectiveness in controlling mosquitoes along with their lack of toxicity. Essential oil nanoemulsions are found to be highly effective when compared to their bulk counterparts. Due to their nano size, they can effectively interact and yield 100 % mortality with the mosquito larvae and encounter with minimal concentrations. This is the main advantage of the nano-sized particles due to which they find application in various disciplines and have also received the attention of researchers globally. There are various components present in essential oils that have been analysed using GC-MS. These findings reflect the challenge to mosquitoes to gain resistance against each component and therefore it requires time. Commercially used repellants are synthesised using materials like DEET are not advisable for topical application on human skin and essential oil nanoemulsions could be an ideal non toxic candidate that can be used against mosquito adults and larvae. However, there are other synthesis, optimisation parameters, and toxicity towards non-target organisms that have to be taken into account when essential oil nanoemulsions are considered for commercial applications. Here we review the strategies used by the nanoemulsions against the mosquito population. Apart from the positive effects, their minor drawbacks also have to be scrutinised in the future.

Cinnamon nanoemulsion mitigates acetamiprid-induced hepatic and renal toxicity in rats: biochemical, histopathological, immunohistochemical, and molecular docking analysis

Acetamiprid (ACDP) is a widely used neonicotinoid insecticide that is popular for its efficacy in controlling fleas in domestic settings and for pets. Our study aims to offer a comprehensive examination of the toxicological impacts of ACDP and the prophylactic effects of cinnamon nanoemulsions (CMNEs) on the pathological, immunohistochemical, and hematological analyses induced by taking ACDP twice a ‎week for 28 days. Forty healthy rats were divided into four groups (n = 10) at random; the first group served as control rats; the second received CMNEs (2 mg/Kg body weight); the third group received acetamiprid (ACDP group; 21.7 mg/Kg body weight), and the fourth group was given both ACDP and CMNEs by oral gavage. Following the study period, tissue and blood samples were extracted and prepared for analysis. According to a GC-MS analysis, CMNEs had several bioactive ingredients that protected the liver from oxidative stress by upregulating antioxidant and anti-inflammatory agents. Our findings demonstrated that whereas ACDP treatment considerably boosted white blood cells (WBCs) and lymphocytes, it significantly lowered body weight gain (BWG), red blood cells (RBCs), hemoglobin (Hb), hematocrit (HCT), and platelets (PLT). ACDP notably reduced antioxidant enzyme activities: superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) and elevated hydrogen peroxide and malondialdehyde levels compared with other groups. ACDP remarkably raised alanine aminotransferase (ALT), aspartate amino transaminase (AST), and alkaline phosphatase (ALP) levels.Moreover, the histopathological and immunohistochemistry assays discovered a severe toxic effect on the liver and kidney following ACDP delivery. Furthermore, cyclooxygenase 2 (COX-2) + immunoexpression was enhanced after treatment with CMNEs. All of the parameters above were returned to nearly normal levels by the coadministration of CMNEs. The molecular docking of cinnamaldehyde with COX-2 also confirmed the protective potential of CMNEs against ACDP toxicity. Our findings highlighted that the coadministration of CMNEs along with ACDP diminished its toxicity by cutting down oxidative stress and enhancing antioxidant capacity, demonstrating the effectiveness of CMNEs in lessening ACDP toxicity.

In vitro acaricidal activity of several natural products against ibex-derived Sarcoptes scabiei

In this study we analysed the effect of the temperature, diverse strains of Bacillus thuringiensis, Lysinibacillus sphaericus and nanoformulations with essential plant oils (EONP) on the survival of Sarcoptes scabiei mites derived from naturally-infested Iberian ibex (Capra pyrenaica). In general, mites maintained at 12ºC survived more than those maintained at 35ºC (40.7 hr and 31.2 hr, respectively). Mites with no treatment survived 27.6 h on average. Mites treated with B. thuringiensis serovar. konkukian and geranium EONP showed significant reduction in their survival. Despite the fact that these agents seem to be promising candidates for controlling sarcoptic mange in the field, further research is still needed to get stable, efficient and eco-friendly acaricides.

Insecticidal Activity of Essential Oils and Their Synergistic Effect on Improving the Efficacy of β-Cypermethrin against Blattella germanica

We screened the contact activity of 32 commercial essential oils (EOs) and their synergistic effect with β-cypermethrin against Blattella germanica. Results showed that the most effective EOs against B. germanica were from Illicium verum, Syzygium aromaticum, and Cinnamomum camphora, with LD50 values of less than 500 μg/insect. The most potent synergistic effects of β-cypermethrin on B. germanica were from Dysphania ambrosioides and Mentha canadensis. Both oils have a co-toxic factor of 133.33. The results of the major compound testing of the EOs showed that trans-anisaldehyde and thymol have the best insecticidal activity against B. germanica, with LD50 values of 141.30 and 138.61 μg/insect, respectively. The compounds with the best synergistic effect on β-cypermethrin were γ-terpinene and linalool at a concentration of 0.5%. The co-toxic factors for γ-terpinene and linalool were 150 and 133.33, respectively, which were similar to the synergistic effect observed with 2% piperonyl butoxide.

Aphid Cerosipha forbesi control using Piper macedoi Yunck essential oil in strawberry crop

Strawberry is a food rich in bioactive compounds with great antioxidant potential. However, due to the high incidence of pests that affect crop cultivation, phytosanitary management still lacks control methods for agroecological cultivation. Thus, the present research aimed to evaluate the chemical composition and the potential of the essential oil of the leaves of Piper macedoi in the control of Cerosipha forbesi in laboratory and semi-field conditions. The concentration of essential oil in the leaves of P. macedoi that showed the highest mortality was 2.0 ml/L of oil, with a mortality above 91% under laboratory conditions. A mortality rate of 80% for all concentrations tested was observed after 24 h in all conditions tested. Thus, using essential oil from the leaf of P. macedoi can be a highly viable strategy in managing the aphid C. forbesi since it showed high mortality rates with small doses of oil.

Eco-friendly management strategies of insect pests: long-term performance of rosemary essential oil encapsulated into chitosan and gum Arabic

This study focused on encapsulation of Rosmarinus officinalis essential oil (EO) on chitosan and gum Arabic matrix in various ratios and with varying essential oil concentrations. Additionally, UV/VIS spectroscopy was used to determine cumulative-release profiles. The insecticidal activity was tested against Tribolium castaneum and Oryzaephilus surinamensis, both pests of stored products. In terms of encapsulation efficiency (EE%) and loading capacity (LC%), capsules had EE at 45.8% and LC at 2.31%. Furthermore, many minor compounds were lost after encapsulation, until identifying only 1,8-cineole, α-terpineol, and camphor after 60 d of storage. The fumigant tests demonstrated that encapsulated EO exhibited an effective control against insect pest during storage periods, namely, 30, 45, and 60 d with 99, 66, and 46% mortality for T. castaneum and 100, 84, 82% mortality for O. surinamensis.

Insights for the control of dried-fruit beetle Carpophilus hemipterus (Nitidulidae) using rosemary essential oil loaded in chitosan nanoparticles

Natural insecticidal products, essentially essential oils and their bioactive compounds are available as an excellent alternative method to control insect pests as well as they are less toxic to human health. However, due to their volatile constituents, encapsulation could be considered as the most suitable solution for their practical application. Therefore, this study aims to explore the insecticidal toxicity of chitosan nanoparticles loaded with Rosmarinus officinalis essential oil against adults of Carpophilus hemipterus. Chitosan nanoparticles were prepared by ionic gelation method with an encapsulation efficiency 41.543.1% and loading capacity 5.24G0.28%. Results revealed that chitosan nanoparticles loaded rosemary oil exhibited interesting insecticidal toxicity towards C. hemipterus adults in stored dates with 50.73% mortality. Overall, this work pointed out that the innovative design method based on chitosan-nanoparticles loaded rosemary oil can be promoted in integrated pest management program for stored date pests.

Toxicity and Repellency Efficacy of Benzyl Alcohol and Benzyl Benzoate as Eco-Friendly Choices to Control the Red Flour Beetle Tribolium castaneum (Herbst. 1797)

Tribolium castaneum is a damaging pest of stored grains, causing significant losses and secreting lethal quinones, which render the grains unfit for human consumption. Chemical insecticides are the most commonly used approach for control; however, they create insecticide resistance and affect the health of humans, animals, and the environment. As a result, it is critical to find an environmentally friendly pest-management strategy. In this study, two naturally occurring chemicals, benzyl alcohol (BA) and benzoyl benzoate (BB), were investigated for insecticidal activity against T. castaneum using different assays (impregnated-paper, contact toxicity, fumigant, and repellency assays). The results showed that BA had a significant insecticidal effect, with the LC50 achieved at a lower concentration in the direct-contact toxicity test (1.77%) than in the impregnated-paper assay (2.63%). BB showed significant effects in the direct-contact toxicity test, with an LC50 of 3.114%, and a lower toxicity in the impregnated-paper assay, with an LC50 of 11.75%. Furthermore, BA exhibited significant fumigant toxicity against T. castaneum, with an LC50 of 6.72 µL/L, whereas BB exhibited modest fumigant toxicity, with an LC50 of 464 µL/L. Additionally, at different concentrations (0.18, 0.09, 0.045, and 0.0225 µL/cm2), BA and BB both showed a notable and potent repelling effect. BA and BB significantly inhibited acetylcholinesterase, reduced glutathione (GSH), and increased malondialdehyde (MDA) in treated T. castaneum. This is the first report of BA insecticidal activity against the red flour beetle. Also, the outcomes of various assays demonstrated that the application of BA induces a potent bio-insecticidal effect. BA may be a promising eco-friendly alternative to control T. castaneum due to its safety and authorization by the EFSA (European Food Safety Authority).

Development and characterization of nanoemulsions loaded with essential oil and β-cypermethrin and their bioefficacy on insect pest of economic and medical importance

BACKGROUND

The development of novel and ecofriendly tools plays an important role in insect pest management. Nanoemulsions (NEs) based on essential oils (EOs) offer a safer alternative for human health and the environment. This study aimed to elaborate and evaluate the toxicological effects of NEs containing peppermint or palmarosa EOs combined with β-cypermethrin (β-CP) using ultrasound technique.

RESULTS

The optimized ratio of active ingredients to surfactant was 1:2. The NEs containing peppermint EO combined with β-CP (NEs peppermint/β-CP) were polydisperse with two peaks at 12.77 nm (33.4% intensity) and 299.1 nm (66.6% intensity). However, the NEs containing palmarosa EO combined with β-CP (NEs palmarosa/β-CP) were monodisperse with a size of 104.5 nm. Both NEs were transparent and stable for 2 months. The insecticidal effect of NEs was evaluated against Tribolium castaneum and Sitophilus oryzae adults, as well as Culex pipiens pipiens larvae. On all these insects, NEs peppermint/β-CP enhanced pyrethroid bioactivity from 4.22- to 16-folds while NEs palmarosa/β-CP, from 3.90- to 10.6-folds. Moreover, both NEs maintained high insecticidal activities against all insects for 2 months, although a slight increase of the particle size was detected.

CONCLUSION

The NEs elaborated in this work can be considered as highly promising formulations for the development of new insecticides. © 2023 Society of Chemical Industry.

Nanobiopesticides: Are they the future of phytosanitary treatments in modern agriculture?

The world's population is continuously increasing; therefore, food availability will be one of the major concerns of our future. In addition to that, many practices and products used, such as pesticides and fertilizers have been shown harmful to the environment and human health and are assumed as being one of the main factors responsible for the loss of biodiversity. Also, climate change could agravate the problem since it causes unpredictable variation of local and regional climate conditions,which frequently favor the growth of diseases, pathogens and pest growth. The use of natural products, like essential oils, plant extracts, or substances of microbial-origin in combination with nanotechnology is one suitable way to outgrow this problem. The most often employed natural products in research studies to date include pyrethrum extract, neem oil, and various essential oils, which when enclosed shown increased resistance to environmental factors. They also demonstrated insecticidal, antibacterial, and fungicidal properties. However, in order to truly determine if these products, despite being natural, would be hazardous or not, testing in non-target organisms, which are rare, must start to become a common practice. Therefore, this review aims to present the existing literature concerning nanoformulations of biopesticides and a standard definition for nanobiopesticides, their synthesis methods and their possible ecotoxicological impacts, while discussing the regulatory aspects regarding their authorization and commercialization. As a result of this, you will find a critical analysis in this reading. The most obvious findings are that i) there are insufficient reliable ecotoxicological data for risk assessment purposes and to establish safety doses; and ii) the requirements for registration and authorization of these new products are not as straightforward as those for synthetic chemicals and take a lot of time, which is a major challenge/limitation in terms of the goals set by the Farm to Fork initiative.

Entomopathogenic Fungi: An Eco-Friendly Synthesis of Sustainable Nanoparticles and Their Nanopesticide Properties

The agricultural industry could undergo significant changes due to the revolutionary potential of nanotechnology. Nanotechnology has a broad range of possible applications and advantages, including insect pest management using treatments based on nanoparticle insecticides. Conventional techniques, such as integrated pest management, are inadequate, and using chemical pesticides has negative consequences. As a result, nanotechnology would provide ecologically beneficial and effective alternatives for insect pest control. Considering the remarkable traits they exhibit, silver nanoparticles (AgNPs) are recognized as potential prospects in agriculture. Due to their efficiency and great biocompatibility, the utilization of biologically synthesized nanosilver in insect pest control has significantly increased nowadays. Silver nanoparticles have been produced using a wide range of microbes and plants, which is considered an environmentally friendly method. However, among all, entomopathogenic fungi (EPF) have the most potential to be used in the biosynthesis of silver nanoparticles with a variety of properties. Therefore, in this review, different ways to get rid of agricultural pests have been discussed, with a focus on the importance and growing popularity of biosynthesized nanosilver, especially silver nanoparticles made from fungi that kill insects. Finally, the review highlights the need for further studies so that the efficiency of bio-nanosilver could be tested for field application and the exact mode of action of silver nanoparticles against pests can be elucidated, which will eventually be a boon to the agricultural industry for putting a check on pest populations.

A Multidimensional Review of Pimpinella anisum and Recommendation for Future Research to Face Adverse Climatic Conditions

Anise, or Pimpinella anisum, has a long history of usage in traditional and alternative medicine, as well as in the pharmaceutical sector. The species is native to Southwest Asia, the Middle East, and the Mediterranean region. The current studies have revealed that wild and cultivated P. anisum are rich in bioactive compounds, such as phenols, tannins, carotenoids, and fatty acids. Different parts of P. anisum plant are used treatment of diseases, the treatment of pathogens for antiviral, antibacterial, and antifungal purposes, and cosmetics. In this paper, we reviewed the current knowledge on geographical distribution, cultivation, chemical compounds, extraction methods, and agronomic and medicinal uses of Pimpinella anisum. Equally, we suggested guidelines for future research to fill the gap in less investigated issues. Data for this paper was gathered via electronic literature search on Google, Google Scholar, and databases counting, Science Direct, Scopus, Springer, PubMed, and Hindawi, from 1930 to 2022. Analyzed data show that Pimpinella anisum is currently recorded from Portugal on the Atlantic Ocean in the west to China in the East. With new extraction methods, such as Ultrasound-Assisted Extraction, scientists have explored the higher quantities of polyphenols, flavonoids, and antioxidants, and revealed new constituents such as trans-anethole and estragole found in essential oil fruits by gas chromatography-mass spectrometry (GC–MS). These compounds showed significant therapeutic benefits against diseases, pathogens, and cosmetic roles. However, with the current impacts of climate change on natural vegetation cover, more investigations are needed to understand how these affect the geographical distribution, metabolic aspects, and chemical properties of Pimpinella anisum. These are suggested to increase the value of the species and ensure its conservation.

Chemical Composition, Toxicity and Repellency of Inula graveolens Essential Oils from Roots and Aerial Parts against Stored-Product Beetle Tribolium castaneum (Herbst)

In this work, essential oils extracted from roots and aerial parts of Inula graveolens by hydrodistillation and their fractions obtained by chromatographic simplification were first investigated for their chemical composition by GC/MS and then evaluated for the first time for their repellency and contact toxicity properties against Tribolium castaneumadults. Twenty-eight compounds were identified in roots essential oil (REO), which accounted for 97.9 % of the total oil composition, with modhephen-8-β-ol (24.7 %), cis-arteannuic alcohol (14.8 %), neryl isovalerate (10.6 %) and thymol isobutyrate (8.5 %) as major constituents. Twenty-two compounds were found in the essential oil from aerial parts (APEO), which accounted for 93.9 % of the total oil, with borneol (28.8 %), caryophylla-4(14),8(15)-dien-6-ol (11.5 %), caryophyllene oxide (10.9 %), τ-cadinol (10.5 %) and bornyl acetate (9.4 %) as main compounds.REO and APEO displayed stronger repellency after 2 h of exposure (80.0 and 90.0 %, respectively) against T. castaneum at the concentration of 0.12 μL/cm² . After fractionation, fractions R₄ and R₅ exhibited greater effects (83.3 % and 93.3 %, respectively) than the roots essential oil. Furthermore, the fractions AP₂ and AP₃ showed higher repellency (93.3 and 96.6 %, respectively) than the aerial parts oil. The LD₅₀ values of oils from roots and aerial parts topically applied were 7.44 % and 4.88 %, respectively. Results from contact toxicity assay showed that fraction R₄ was more effective than the roots oil with LD₅₀ value of 6.65 %. These results suggests that essential oils of roots and aerial parts from I. graveolens may be explored as potential natural repellent and contact insecticides against T. castaneum in stored products.

Emerging Biopharmaceuticals from Pimpinella Genus

Evolved over eons to encode biological assays, plants-derived natural products are still the first dawn of drugs. Most researchers have focused on natural compounds derived from commonly used Pimpinella species, such as P. anisum, P. thellungiana, P. saxifrage, and P. brachycarpa, to investigate their antioxidant, antibacterial, and anti-inflammatory properties. Ethnopharmacological studies demonstrated that the genus Pimpinella has the homology characteristics of medicine and food and mainly in the therapy of gastrointestinal dysfunction, respiratory diseases, deworming, and diuresis. The natural product investigation of Pimpinella spp. revealed numerous natural products containing phenylpropanoids, terpenoids, flavonoids, coumarins, sterols, and organic acids. These natural products have the potential to provide future drugs against crucial diseases, such as cancer, hypertension, microbial and insectile infections, and severe inflammations. It is an upcoming field of research to probe a novel and pharmaceutically clinical value on compounds from the genus Pimpinella. In this review, we attempt to summarize the present knowledge on the traditional applications, phytochemistry, and pharmacology of more than twenty-five species of the genus Pimpinella.

Investigation of insecticidal activity of two Rhododendron species on stored-product insects

This study was designed to investigate the insecticidal activity of the essential oils (EOs) and extracts from Rhododendron rufum and Rhododendron przewalskii. The EOs were extracted from the leaves of R. Rufum and R. przewalskii by hydro-distillation and their chemical components were analyzed by gas chromatography-mass spectrometry (GC-MS). The repellency, contact toxicity and antifeedant activity of the EOs and extracts were evaluated against Sitophilus oryzae and Tribolium castaneum along with those of their main components. A total of nine compounds were identified from the EO of R. Rufum, and the most abundant component was myristicin (79.72%). The EO of R. Rufum exhibited repellent activities at different levels and its main compound myristicin showed contact toxicity and repellent effects against S. oryzae and T. castaneum. Meanwhile, by bioassay-guided fractionation, four compounds with strong antifeedant activities against T. castaneum, 24-methylenecycloartanyl-2'E, 4'Z-tetradecadienoate (1), methyl thyrsiflorin B acetate (2), friedelin (3) and Excoecarin R1 methyl ester (4) were separated and identified from the ethanol extract of R. przewalskii for the first time. Considering the significant anti-insect activities, the EOs and extracts of R. Rufum and R. przewalskii might be used in integrated pest strategies, establishing a good perspective for the comprehensive use of natural plant resources of Rhododendron genus.

Simultaneous Optimization of Phenolic Compounds and Antioxidant Abilities of Moroccan Pimpinella anisum Extracts Using Mixture Design Methodology

Pimpinella anisum (anise) is a dense vegetal matrix with considerable amounts of bioactive components known for its pharmacological properties. The optimization of extraction constitutes an important key to improving efficacy and avoiding wasting time. Within this framework, the present study was designed to select the most appropriate extractor solvent mixture to extract phenolic and flavonoids using Mixture Design Methodology. The concerned responses were the total phenolic content (TPC), total flavonoid content (TFC) and antioxidant ability examined by 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay. Before mixture design optimization, a screening of solvents was conducted on ten polar and nonpolar solvents to choose the best solvents that give a maximum of total phenolic compounds. This first step has shown that water, ethanol and methanol were the best-used solvents. Later, an augmented centroid design investigated the solvent system’s optimization. The results of simultaneous optimization have shown that the ternary mixture containing 44% of water, 22% of ethanol and 34% of methanol was the most appropriate for simultaneous maximization of TPC, TFC and antioxidant activity with 18.55 mg GAE/g, 7.16 mg QE/g and 0.56 mg/mL, respectively. Our results have shown that using mixture design as an optimization technique was an excellent way to choose the most suitable mixture to extract bioactive compounds, which may represent a promising method of multi-purpose extraction, especially in the pharmaceutical and food sectors.

Essential oils loaded on polymeric nanoparticles: bioefficacy against economic and medical insect pests and risk evaluation on terrestrial and aquatic non-target organisms

This paper introduces the lethal, sublethal, and ecotoxic effects of peppermint and palmarosa essential oils (EOs) and their polymeric nanoparticles (PNs). The physicochemical analyses indicated that peppermint PNs were polydisperse (PDI > 0.4) with sizes of 381 nm and loading efficiency (LE) of 70.3%, whereas palmarosa PNs were monodisperse (PDI < 0.25) with sizes of 191 nm and LE of 89.7%. EOs and their PNs were evaluated on the adults of rice weevil (Sitophilus oryzae L.) and cigarette beetle (Lasioderma serricorne F.) and the larvae of Culex pipiens pipiens Say. On S. oryzae and L. serricorne, PNs increased EOs' lethal activity, extended repellent effects for 84 h, and also modified behavioral variables during 24 h. Moreover, EOs and PNs generated toxic effects against C. pipiens pipiens. On the other hand, peppermint and palmarosa EOs and their PNs were not toxic to terrestrial non-target organisms, larvae of mealworm (Tenebrio molitor L.), and nymphs of orange-spotted cockroach (Blaptica dubia S.). In addition, PNs were slightly toxic to aquatic non-target organisms, such as brine shrimp (Artemia salina L.). Therefore, these results show that PNs are a novel and eco-friendly formulation to control insect pests.

Ultrasound-assisted nanoemulsion of Trachyspermum ammi essential oil and its constituent thymol on toxicity and biochemical aspect of Aedes aegypti

Aedes aegypti is the main vector of yellow fever, chikungunya, Zika, and dengue worldwide and is managed by using chemical insecticides. Though effective, their indiscriminate use brings in associated problems on safety to non-target and the environment. This supports the use of plant-based essential oil (EO) formulations as they are safe to use with limited effect on non-target organisms. Quick volatility and degradation of EO are a hurdle in its use; the present study attempts to develop nanoemulsions (NE) of Trachyspermum ammi EO and its constituent thymol using Tween 80 as surfactant by ultrasonication method. The NE of EO had droplet size ranging from 65 ± 0.7 to 83 ± 0.09 nm and a poly dispersity index (PDI) value of 0.18 ± 0.003 to 0.20 ± 0.07 from 1 to 60 days of storage. The NE of thymol showed a droplet size ranging from 167 ± 1 to 230 ± 1 nm and PDI value of 0.30 ± 0.03 to 0.40 ± 0.008 from 1 to 60 days of storage. The droplet shape of both NEs appeared spherical under a transmission electron microscope (TEM). The larvicidal effect of NEs of EO and thymol was better than BEs (Bulk emulsion) of EO and thymol against Ae. aegypti. Among the NEs, thymol (LC₅₀ 34.89 ppm) had better larvicidal action than EO (LC₅₀ 46.73 ppm). Exposure to NEs of EO and thymol causes the shrinkage of the larval cuticle and inhibited the acetylcholinesterase (AChE) activity in Ae. aegypti. Our findings show the enhanced effect of NEs over BEs which facilitate its use as an alternative control measure for Ae. aegypti.

Botanical Oils Isolated from Simmondsia chinensis and Rosmarinus officinalis Cultivated in Northern Egypt: Chemical Composition and Insecticidal Activity against Sitophilus oryzae (L.) and Tribolium castaneum (Herbst)

The rice weevil, Sitophilus oryzae (L.), and the red flour beetle, Tribolium castaneum (Herbst), are key stored-product pests in Egypt and worldwide. The extensive use of synthetic insecticides has led to adverse effects on the environment, human health, and pest resistance. As a result, environmentally friendly pest management alternatives are desperately required. The botanical oils of jojoba, Simmondsia chinensis (L.), and rosemary, Rosmarinus officinalis L. plants growing in Egypt were extracted, identified by gas chromatography/mass spectrometry (GC-MS), and evaluated for their insecticidal activity against S. oryzae and T. castaneum. The main constituents identified in BOs were carvyl acetate (20.73%) and retinol (16.75%) for S. chinensis and camphor (15.57%), coumarin (15.19%), verbenone (14.82%), and 1,8-cineole (6.76%) for R. officinalis. The S. chinensis and R. officinalis BOs caused significant contact toxicities against S. oryzae and T. castaneum adults, providing LC₅₀ values of 24.37, 68.47, and 11.58, 141.8 ppm at 3 days after treatment (DAT), respectively. S. chinensis oil exhibited significant fumigation toxicity against both insects; however, it was more effective against S. oryzae (LC₅₀ = 29.52 ppm/L air) than against T. castaneum (LC₅₀ = 113.47 ppm/L air) at 3 DAT. Although the essential oil (EO) of R. officinalis significantly showed fumigation toxicity for S. oryzae (LC₅₀ = 256.1 and 0.028 ppm/L air at 1 and 3 DAT, respectively), it was not effective against T. castaneum. These BOs could be beneficial for establishing IPM programs for suppressing S. oryzae and T. castaneum.

Lethal and sublethal effects of an emulsion based on Pogostemon cablin (Lamiaceae) essential oil on the coffee berry borer, Hypothenemus hampei

The global search for eco-friendly and human-safe pesticides has intensified, and research on essential oils (EOs) has expanded due to their remarkable insecticidal activities and apparent human-safe. Despite this, most of the literature focuses on short-term and simplified efforts to understand lethal effects, with only a few comprehensive studies addressing sublethal exposures. To fill this shortcoming, we explore the lethal and sublethal effects of Pogostemon cablin (Lamiaceae) EO and an EO-based emulsion (18%) using the coffee berry borer Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae) as a model. First, we determine the toxicity of EO and EO-based emulsion using dose-mortality curves and lethal times. Second, we subjected adult females of H. hampei to sublethal doses to assess whether they affected their behavior, reproductive output, and histological features. Our findings reveal that patchoulol (43.05%), α-Guaiene (16.06%), and α-Bulnesene (13.69%) were the main components of the EO. Furthermore, the EO and its emulsion had similar toxicity, with dose-mortality curves and lethal times overlapping 95% confidence intervals. We also observed that sublethal exposure of females of H. hampei reduces reproduction and feeding, increases walking activity, and causes histopathological changes in the midgut. This study advances the knowledge of the lethal and sublethal effects of an eco-friendly substance on insects.Responsible Editor: Giovanni Benelli.

Co-encapsulation of Pimpinella anisum and Coriandrum sativum essential oils based synergistic formulation through binary mixture: Physico-chemical characterization, appraisal of antifungal mechanism of action, and application as natural food preservative

The present study aimed to co-encapsulate binary synergistic formulation of Pimpinella anisum and Coriandrum sativum (PC) essential oils (0.75:0.25) into chitosan nanoemulsion (Nm-PC) with effective inhibition against fungal proliferation, aflatoxin B₁ (AFB₁) secretion, and lipid peroxidation in stored rice. Physico-chemical characterization of Nm-PC by SEM, FTIR, and XRD confirmed successful encompassment of PC inside the chitosan nanomatrix with efficient interaction by functional groups and reduction in crystallinity. Nm-PC showed superior antifungal, antiaflatoxigenic, and antioxidant activities over unencapsulated PC. Reduction in ergosterol biosynthesis and enhanced leakage of Ca²⁺, K⁺, Mg²⁺ ions and 260, 280 nm absorbing materials by Nm-PC fumigation confirmed irreversible damage of plasma membrane in toxigenic Aspergillus flavus cells. Significant diminution of methylglyoxal in A. flavus cells by Nm-PC fumigation illustrated biochemical mechanism for antiaflatoxigenic activity, suggesting future exploitation for development of aflatoxin resistant rice varieties through green transgenic technology. In silico findings indicated specific stereo-spatial interaction of anethole and linalool with Nor-1 protein, validating molecular mechanism for AFB₁ inhibition. In addition, in situ investigation revealed effective protection of stored rice against fungal occurrence, AFB₁ biosynthesis, and lipid peroxidation without affecting organoleptic attributes. Moreover, mammalian non-toxicity of chitosan entrapped PC synergistic nanoformulation could provide exciting potential for application as eco-smart safe nano-green food preservative.

Aphicidal activity of farnesol against the green peach aphid - Myzus persicae

BACKGROUND

Myzus persicae (Hemiptera: Aphididae) is considered one of most important agricultural pests in the world. It is one of the main pests in protected pepper crops under glasshouse conditions in Southeastern Spain, but its control is limited as a consequence of the few available authorized insecticides and their incompatibility with the natural enemies. Some essential oils and pure compounds such as anise (Pimpinella anisum) or farnesol are repellent and/or toxic to aphids. Their use as a botanical insecticides can be an alternative for aphid control in pepper.

RESULTS

The effect of farnesol was evaluated against M. persicae in a new bioassay developed to test the contact effect (aqueous formulation of the products) on aphids in laboratory conditions. Aniseed essential oil, geraniol and (Z)-jasmone at 0.6% causes an aphid mortality of >50%; and farnesol was the most effective (93.67% mortality). Farnesol nanoemulsions between 0.2% and 0.6% were formulated with an IKA-Labor Pilot dispersing machine (7940 rpm for 10 min) using Tween 80 as a surfactant. These formulations were tested on field experiments (glasshouse conditions) on pepper crops for 2 years. Foliar applications of farnesol at a concentration of 0.4% in field conditions causes a high reduction in aphid populations, with efficacies of ≈70-80% with respect to the control, similar to or even higher than the efficacy of the reference pyrethrin insecticide.

CONCLUSION

Farnesol showed a great aphicidal effect against M. persicae. The use of this molecule in integrated pest management programs combined with natural enemies is a good option for future control of M. persicae. © 2022 Society of Chemical Industry.

Combinations of plant essential oils and their major compositions inducing mortality and morphological abnormality of Aedes aegypti and Aedes albopictus

Extensive uses of synthetic insecticides to control mosquito's populations have induced the insects to develop resistance against them, rendering them ineffective today. Moreover, they cause serious impacts on human health and the ecosystem. Therefore, safe and effective natural alternatives are needed. This study evaluated the larvicidal and pupicidal activities of essential oils (EOs) from Illicium verum and Zanthoxylum limonella and the major constituents against Aedes aegypti and Aedes albopictus mosquitoes as well as recorded their morphological aberrations at death. The GC-MS analysis showed that trans-anethole was the major constituent of I. verum EO, and limonene was the major constituent of Z. limonella EO. Both were more effective against the larvae and pupae of Ae. aegypti than those of Ae. albopictus. A 2.5% I. verum EO + 2.5% trans-anethole combination showed the highest larvicidal and pupicidal effects against Ae. aegypti and Ae. albopictus with an LT₅₀ ranging from 0.2-6.9 h. Between the two tested constituents, trans-anethole exhibited stronger larvicidal and pupicidal activities (LC₅₀ ranging 2.4–3.4%) against the two tested mosquito species than d-limonene (LC₅₀ ranging 2.5–3.7%). Most importantly, 5% trans-anethole, 5% d-limonene, and 2.5% I. verum EO + 2.5% trans-anethole were more effective (LT₅₀ ranging 0.1–0.3 h) than 1% (w/w) temephos (LT₅₀ ranging 2.9–3.1 h). Morphological aberrations at death observed were such as color pigment and thorax shape abnormalities. To conclude, trans-anethole, d-limonene, and a combination of I. verum EO + trans-anethole, are natural compounds that not only are as effective as temephos at the time of this study, but should be also be much safer to human health.

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Trans-anethole and limonene are strongly insecticidal against two mosquito species.

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I. verum EO + trans-anethole was very strong larvicide and pupicide.

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I. verum EO + trans-anethole was much more effective than temephos.

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All formulations effected some morphological changes at time of death.

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These long-used natural compounds should be much safer than temephos.

Nanomaterials for Postharvest Management of Insect Pests: Current State and Future Perspectives

Globally, between one quarter and one-third of total grains produced each year are lost during storage mainly through infestation of insect pests. Among the available control options such as chemical and physical techniques, fumigation with aluminum phosphide (AlP) is so far considered the best control strategy against storage insect pests. However, these insect pests are now developing resistance against AIP due to its indiscriminate use due to non-availability of any effective alternative control option. Resistance to AIP among storage insect pests is increasing, and its inhalation has shown adverse effects on animals and human beings. Nanotechnology has opened up a wide range of opportunities in various fields such as agriculture (pesticides, fertilizers, etc.), pharmaceuticals, and electronics. One of the applications of nanotechnology is the usage of nanomaterial-based insecticide formulations for mitigating field and storage insect pests. Several formulations, namely, nanoemulsions, nanosuspensions, controlled release formulations, and solid-based nanopesticides, have been developed with different modes of action and application. The major advantage is their small size which helps in proper spreading on the pest surface, and thus, better action than conventional pesticides is achieved. Besides their minute size, these have no or reduced harmful effects on non-target species. Nanopesticides can therefore provide green and efficient alternatives for the management of insect pests of field and storage. However, an outcry against the utilization of nano-based pesticides is also revealed. It is considered by some that nano-insecticides may also have hazardous effects on humans as well as on the environment. Due to limited available data, nanopesticides have become a double-edged weapon. Therefore, nanomaterials need to be evaluated extensively for their large-scale adoption. In this article, we reviewed the nanoformulations that are developed and have proved effective against the insect pests under postharvest storage of grains.

Identification and Functional Analysis of Differentially Expressed Genes in Myzus persicae (Hemiptera: Aphididae) in Response to Trans-anethole

Plant essential oils, with high bioactivity and biodegradability, provide promising alternatives to synthetic pesticides for pest control. Trans-anethole is the major component of essential oil from star anise, Illicium verum Hook. The compound has a strong contact toxicity against the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), which is a major insect pest of many vegetables and crops. However, little information is known about how M. persicae responds to trans-anethole at the molecular level. We conducted a comparative transcriptome analysis of M. persicae in response to a LD50 dose of trans-anethole. A total of 559 differentially expressed genes were detected in the treated individuals, with 318 genes up-regulated, and 241 genes down-regulated. Gene ontology (GO) analysis revealed that these genes were classified into different biological processes and pathways. We also found that genes encoding ATP-binding cassette (ABC) transporters, DnaJ, and cuticle proteins were dramatically up-regulated in response to trans-anethole. To study the function of these genes, we performed RNA interference (RNAi) analysis. Knockdown of an ABC transporter gene (ABCG4) and a DnaJ gene (DnaJC1) resulted in a significantly increased mortality rate in M. persicae following trans-anethole exposure, indicating the involvement of these two genes in the toxicity response to trans-anethole. The findings provide new insights into the mechanisms of M. persicae in coping with plant essential oils.

Bio-Insecticidal Nanoemulsions of Essential Oil and Lipid-Soluble Fractions of Pogostemon cablin

The present study aimed to develop nanoemulsions (NEs) of essential oil (EO) and lipid-soluble extract (HE) of Pogostemon cablin leaves using biosurfactant, saponin. Hydro-distilled EO and fat-soluble HE were analyzed using GC-MS, which revealed 38.7 ± 2.7% and 37.5 ± 2.1% patchoulol, respectively. EO and HE were formulated with saponin to prepare corresponding coarse emulsions (CEs); furthermore, high-speed homogenization for 2 min was followed by ultrasonication for 3 min with constant frequency of 50 kHz. of the CEs resulted in respective NEs. NEs were characterized for the physico-chemical properties such as emulsion intrinsic stability, particle size distribution, polydispersity index (PDI), and transmission electron microscopy (TEM) for morphology and accurate nanodroplet diameters. CEs and NEs were investigated for insecticidal efficacy against adults of Tetranychus urticae and larvae of Spodoptera litura. Stable NEs of EO and HE at 500 μg mL^-1 concentration exhibited corresponding average particle size of 51.7 and 89.9 nm, while TEM image revealed spherical-shaped droplets with the average droplet diameters of 15.3 and 29.4 nm, respectively. NEs of EO and HE displayed highest efficacy in contact toxicity (LC₅₀ 43.2 and 58.4 μg mL^-1) after 48 h and fumigant toxicity (LC₅₀ 9.3 and 13.6 μg mL^-1) after 24 h against T. urticae. In addition, NEs of EO showed considerable antifeedant and feeding deterrent action (AI 99.21 ± 0.74 and FI 99.73 ± 1.24) against S. litura larvae.

A Comprehensive Review of the Coffee Leaf Miner Leucoptera coffeella (Lepidoptera: Lyonetiidae)-A Major Pest for the Coffee Crop in Brazil and Others Neotropical Countries

Simple Summary

Coffee is produced in more than 60 countries by 25 million coffee producers, most of whom are smallholders in emergent countries. More than a beverage intake, coffee has become a ritual for an increasing number of consumers across the globe. This rising market demands modern management to improve grain quality, environment protecting, and produce pesticide-free products. Among several challenges to overcome, the coffee leaf miner (CLM) pest is one of the most severe threats to the coffee crop, especially in neotropical countries, such as Brazil, the world’s largest producer. Responsible for losses ranging from 30–70%, the CLM impairs the grain production and quality, which negatively reflects on the coffee production chain. Drawback aspects caused by chemical control with pesticides, such as the harmful effects to human health and environment and the selection of resistant-insect populations, prompt scientists to improve integrated pest management (IPM) tools. Therefore, the development of new resistant cultivars, biological control, nano-biopesticide products and other approaches are important strategies to a sustainable CLM control design. This review addresses basic knowledge of the insect L. coffeella and proposes novel insights for an IPM view.

Abstract

The coffee leaf miner (CLM) Leucoptera coffeella moth is a major threat to coffee production. Insect damage is related to the feeding behavior of the larvae on the leaf. During the immature life stages, the insect feeds in the mesophyll triggering necrosis and causing loss of photosynthetic capacity, defoliation and significant yield loss to coffee crops. Chemical control is used to support the coffee production chain, though market requirements move toward conscious consumption claiming for more sustainable methods. In this overview, we discuss aspects about the CLM concerning biology, history, geographical distribution, economic impacts, and the most relevant control strategies in progress. Insights to develop an integrated approach for a safer and eco-friendly control of the CLM are discussed here, including bio-extracts, nanotechnology, pheromones, and tolerant cultivars.

Recent advances and future perspective of essential oils in control Colletotrichum spp.: A sustainable alternative in postharvest treatment of fruits

The world population growth has raised concerns about food security. Agricultural systems are asked to satisfy a growing demand for food with increasingly limited resources, and simultaneously still must reduce the impacts on the environment. This scenario encourages the search for safe and sustainable production strategies. Reducing losses in the production process can be one of the main ways to guarantee food safety. In fruticulture, it is estimated that more than 50% of the production can be lost between harvest and the final consumer due to postharvest diseases caused by phytopathogenic fungi. The fungi of the genus Colletotrichum are opportunistic and are associated with several diseases, being the anthracnose the most relevant in terms of the quality and yield losses in fruit species around worldwide. To control these diseases, the use of synthetic fungicides has been the main instrument utilized, however, because of their phytotoxicity to human health, the environment, and strong selection pressure imposed by continuous applications, the fungicides have caused resistance in the pathogen populations. So reducing the excessive application of these products is indispensable for human health and for sustainable Agriculture. Towards this purpose, research has been carried out to identify the phytopathological potentiality of essential oils (EOs) extracted from plants. Therefore, this review aims to contribute to the formation of knowledge bases, about the discoveries, recent advances, and the use of EOs as a strategy to alternatively control fungal disease caused by Colletotrichum spp. in postharvest fruits. Here, we provide valuable information exploring the application potential of essential oils as commercially useful biorational pesticides for food preservation, contributing to sustainable production and global food security.

Potential of Essential Oils from Anise, Dill and Fennel Seeds for the Gypsy Moth Control

The gypsy moth (Lymantria dispar L. (Lepidoptera: Erebidae)) is a serious pest of hardwood forests. In the search for an environmentally safe means of its control, we assessed the impact of different concentrations of essential oils (EOs) from the seeds of three Apiaceae plants (anise Pimpinella anisum, dill Anethum graveolens, and fennel Foeniculum vulgare) on behavior, mortality, molting and nutritional physiology of gypsy moth larvae (GML). EOs efficacy was compared with commercial insecticide NeemAzal®-T/S (neem). The main compounds in the Eos were trans-anethole in anise; carvone, limonene, and α-phellandrene in dill; and trans-anethole and fenchone in fennel seed. At 1% EOs concentration, anise and fennel were better antifeedants and all three EOs were more toxic than neem. Neem was superior in delaying 2nd to 3rd larval molting. In the 4th instar, 0.5%, anise and fennel EOs decreased relative consumption rate more than neem, whereas all three EOs were more effective in reducing growth rate, approximate digestibility and efficiency of conversion of food into body mass leading to higher metabolic costs to GML. Decrease in consumption and metabolic parameters compared to control GML confirmed that adverse effects of the EOs stem from both pre- and post-ingestive mechanisms. The results indicate the potential of three EOs to be used for gypsy moth control.

Essential Oil-Based Nano-Biopesticides: Formulation and Bioactivity against the Confused Flour Beetle Tribolium confusum

Post-harvest pest control can rely on few approved pesticides and tools; hence, there is a rising interest in new sustainable, eco-friendly approaches. In this study, eight commercial essential oils (EOs) (anise Pimpinella anisum, artemisia Artemisia vulgaris, fennel Foenicum vulgare, garlic Allium sativum, lavender Lavandula angustifolia, mint Mentha piperita, rosemary Rosmarinus officinalis, and sage Salvia officinalis) were selected for their bioactivity and commercial availability, and then formulated in nano-emulsions. Repellency and acute toxicity of the developed nano-formulations were tested against a key stored product pest, Tribolium confusum (Coleoptera: Tenebrionidae). All the developed nano-emulsions presented optimal physical characteristics (droplet dimension = 95.01–144.30 nm; PDI = 0.146–0.248). All the formulations were repellent over time tested against adult beetles, in area preference bioassays. The best repellent was the anise EO-based formulation (RC50 = 0.033 mg). Mortality values from cold aerosol trials showed that the majority of tested EOs caused immediate acute toxicity, and garlic EO nano-emulsion caused the highest mortality of T. confusum adults (LC50 = 0.486 mg/L of air). EO-based nano-insecticides, used as cold aerosol and gel, are promising control methods against stored product pests, which can be integrated and combined with other sustainable biorational approaches.

The potential of Apiaceae species as sources of singular phytochemicals and plant-based pesticides

The Apiaceae Lindl. (=Umbelliferae Juss.), which includes several economical important vegetables, herbs, and spices, is one of the most numerous plant family. Umbelliferous crops (namely anise, fennel, carrot, coriander, parsley, etc.) are also valuable sources of botanical flavoring agents and fragrances. In addition, Apiaceae species yield a wide variety of distinctive specialized metabolites (i.e, volatile phenylpropanoids, furanocoumarins, sesquiterpene coumarins, polyacetylenes, and phthalides), some of them been described as uncommon natural phytochemicals exclusive of the family, which offers a great potential for bioprospection. Numerous studies have pointed out the outstanding biological activity of extracts and several classes of phytochemicals from Apiaceae species. Emphasis has been given to essential oils (EOs) and their constituents activities, most likely because this type of plant added value product benefits from a larger acceptance and application potential in integrated pest management (IPM) and integrated vector management (IVM) programs. Several species of the family offer a variety of unique compounds with great potential as biopesticidal and/or synergizing agents. Investigations covering their activity toward agricultural pests and phytopathogens have increased in the last years, nevertheless the interest remains strongly focus on arthropod species, predominantly those acting as vectors of human diseases. From our survey, it is patent the gap of knowledge concerning the potential molluscicidal properties of Apiaceae extracts/phytochemicals, as well as their herbicidal activities against invasive plant species. In this review, we propose to highlight the potential of Apiaceae species as suitable sources of bioactive phytochemicals with great relevance within the frame of plant-based pesticides R&D, and will discuss their applicability in real-world scenarios considering the recent developments regarding the design of stable formulations incorporating Apiaceae bioactive products. We expect that this review will encourage researchers to consider undervalued Apiaceae species as alternative sources of bioactive compounds and will give a contribute to the field by suggesting new research topics.

Control of red flour beetle (Tribolium castaneum) in feeds and commercial poultry diets via using a blend of clove and lemongrass extracts

The insects' infestation decreases the nutritive value of the stored grains and causes losses in its weight, quality, or economic values. The aim of the present study was to investigate the efficiency of a natural product of clove and lemongrass extracts in controlling of red flour beetle (Tribolium castaneum) in different feedstuffs and commercial poultry diets. Different concentrations of the tested product (5, 10, 20, 50, 100 mg) were mixed with 10 g of different feedstuffs and poultry diets, and incubated at different time points. The percent repellency (PR), toxicity effect, and antifeedant activity of the plant extracts compound were assessed. The PR was detected depending on the choice method. It was found that the PR was dose and time dependent. The highest doses (50 or 100 mg/10 g feed) achieved the highest repellency effect reaching 70% at 24 h post-application (PA). The minimal PR was reported by the lowest dose of 5 mg/10 g feed reaching 50% at 24 h PA. Moreover, the PR was found to decrease by time. The toxicity effect of this natural product on T. castaneum was cumulative, not acute, in which it was recorded after 1 month of application. Besides, this effect needs high doses of the product (at dose 500 or 1000 mg/50 g feed). The used product achieved a clear antifeedant activity against T. castaneum, as the feeding deterrent index (FDI %) for corn grains was 98.5% at 1.0 and 2.0% concentration, whereas for wheat grains there was a significant difference between both concentration (96.0 vs. 74.4%). In addition, the weight loss of control corn and wheat grains was higher than the treated ones, and it was about 3.15% and 2.0% per month for corn and wheat, respectively. In conclusion, the clove and lemongrass extracts had a repellency effect reaching to 70%. Moreover, it had a lethal effect on T. castaneum. In addition, it can reduce the weight loss of the infested feeds and consequently increasing its FDI %. Therefore, the clove and lemongrass extract blend can be used to protect the feedstuffs from the damage by this insect.

Biological Activity of trans-2-Hexenal Against the Storage Insect Pest Tribolium castaneum (Coleoptera: Tenebrionidae) and Mycotoxigenic Storage Fungi

Grain commodities in postharvest storage often deteriorate because of fungal and insect attacks. With the green consumption requirements of consumers, ecofriendly and safe pesticides are needed for grain storage. The current study investigated the efficacy of the plant volatile compound trans-2-hexenal against the storage insect pest Tribolium castaneum (Herbst) and three commonly occurring storage fungi, viz., Fusarium graminearum, Aspergillus flavus, and Aspergillus niger, to recommend its application as a botanical fumigant for grain commodities. trans-2-Hexenal weakly repels T. castaneum but has favorable insecticidal activity against multiple developmental stages of T. castaneum, ranging in sensitivity as follows: eggs (LC50 = 14.3 µl/l) > adults (31.6 µl/l) > young larvae (42.1 µl/l) > mature larvae (64.5 µl/l) > pupae (70.5 µl/l). Moreover, trans-2-hexenal caused a high malformation rate and high mortality in adults developed from fumigated pupae. In a 7-d grain, trans-2-hexenal at 0.8 µl/ml provided an appreciable efficacy (81.3%), and concentrations ≥ 0.1 µl/ml completely inhibited the offspring of T. castaneum. trans-2-Hexenal was nonphytotoxic to the seed germination and seedling growth of wheat seeds. Furthermore, trans-2-hexenal completely inhibited the growth of A. flavus, F. graminearum, and A. niger at 5, 10, and 10 µl/l, respectively. The favorable biological activity of trans-2-hexenal against T. castaneum and three frequently occurring mycotoxigenic storage fungi indicated the potential of trans-2-hexenal for simultaneously controlling pests and pathogens, which could reduce its application frequency in grains and decrease pesticide resistance risks.

Essential oils and their bioactive compounds as eco-friendly novel green pesticides for management of storage insect pests: prospects and retrospects

The control of storage insect pests is largely based on synthetic pesticides. However, due to fast growing resistance in the targeted insects, negative impact on humans and non-target organisms as well as the environment, there is an urgent need to search some safer alternatives of these xenobiotics. Many essential oils (EOs) and their bioactive compounds have received particular attention for application as botanical pesticides, since they exhibited high insecticidal efficacy, diverse mode of action, and favourable safety profiles on mammalian system as well as to the non-target organisms. Data collected from scientific articles show that these EOs and their bioactive compounds exhibited insecticidal activity via fumigant, contact, repellent, antifeedant, ovicidal, oviposition deterrent and larvicidal activity, and by inhibiting/altering important neurotransmitters such as acetylcholine esterase (AChE) and octopamine or neurotransmitter inhibitor γ-amino butyric acid (GABA), as well as by altering the enzymatic [superoxide dismutase (SOD), catalase (CAT), peroxidases (POx), glutathione-S-transferase (GST) and glutathione reductase (GR)] and non-enzymatic [glutathione (GSH)] antioxidant defence systems. However, in spite of promising pesticidal efficacy against storage pests, the practical application of EOs and their bioactive compounds in real food systems remain rather limited because of their high volatility, poor water solubility and susceptibility towards degradation. Nanoencapsulation/nanoemulsion of EOs is currently considered as a promising tool that improved water solubility, enhanced bio-efficacy, stability and controlled release, thereby expanding their applicability.

Developing a Hazomalania voyronii Essential Oil Nanoemulsion for the Eco-Friendly Management of Tribolium confusum, Tribolium castaneum and Tenebrio molitor Larvae and Adults on Stored Wheat

Most insecticides commonly used in storage facilities are synthetic, an issue that generates concerns about food safety and public health. Therefore, the development of eco-friendly pest management tools is urgently needed. In the present study, a 6% (w/w) Hazomalania voyronii essential oil-based nanoemulsion (HvNE) was developed and evaluated for managing Tribolium confusum, T. castaneum, and Tenebrio molitor, as an eco-friendly wheat protectant. Larval and adult mortality was evaluated after 4, 8, and 16 h, and 1, 2, 3, 4, 5, 6, and 7 days, testing two HvNE concentrations (500 ppm and 1000 ppm). T. confusum and T. castaneum adults and T. molitor larvae were tolerant to both concentrations of the HvNE, reaching 13.0%, 18.7%, and 10.3% mortality, respectively, at 1000 ppm after 7 days of exposure. However, testing HvNE at 1000 ppm, the mortality of T. confusum and T. castaneum larvae and T. molitor adults 7 days post-exposure reached 92.1%, 97.4%, and 100.0%, respectively. Overall, the HvNE can be considered as an effective adulticide or larvicide, depending on the target species. Our results highlight the potential of H. voyronii essential oil for developing green nanoinsecticides to be used in real-world conditions against key stored-product pests.

Emulsions containing essential oils, their components or volatile semiochemicals as promising tools for insect pest and pathogen management

Most of the traditional strategies used for facing the management of insect pest and diseases have started to fail due to different toxicological issues such as the resistance of target organism and the impact on environment and human health. This has made mandatory to seek new effective strategies, which minimize the risks and hazards without compromising the effectiveness of the products. The use of essential oils, their components and semiochemicals (pheromones and allelochemicals) has become a promising safe and eco-sustainable alternative for controlling insect pest and pathogens. However, the practical applications of this type of molecules remain rather limited because their high volatility, poor solubility in water and low chemical stability. Therefore, it is required to design strategies enabling their use without any alteration of their biological and chemical properties. Oil-in-water nano/microemulsions are currently considered as promising tools for taking advantage of the bioactivity of essential oils and their components against insects and other pathogens. Furthermore, these colloidal systems also allows the encapsulation and controlled release of semiochemicals, which enables their use in traps for monitoring, trapping or mating disruption of insects, and in push-pull strategies for their behavioral manipulation. This has been possible because the use of nano/microemulsions allows combining the protection provided by the hydrophobic environment created within the droplets with the enhanced dispersion of the molecules in an aqueous environment, which favors the handling of the bioactive molecules, and limits their degradation, without any detrimental effect over their biological activity. This review analyzes some of the most recent advances on the use of emulsion-like dispersions as a tool for controlling insect pest and pathogens. It is worth noting that even though the current physico-chemical knowledge about these systems is relatively poor, a deeper study of the physico-chemical aspects of nanoemulsions/microemulsions containing essential oils, their components or semiochemicals, may help for developing most effective formulations, enabling the generalization of their use.

Nanobiopesticides: development and inseticidal activity of nanoemulsions containing lemongrass or eucalyptus oils

The bioinsecticides, like essential oils, are a promising alternative in pest control. However, these oils have some limitations, such as instability and low solubility. These limitations can be circumvented through nanotechnology, with the nanoemulsification of these compounds. Therefore, the objective of this study was to prepare, characterize and explore the insecticidal activity against adult flies of nanoemulsions containing essential oil of lemongrass or eucalyptus. The nanoemulsions were prepared by the high-energy method and presented droplet size smaller than 125 nm, with polydispersity index of 0.2, pH acid and spherical morphology. The insecticidal activity was evaluated by the Topical Application Method and Exposure Impregnated Paper Exposure, where it was possible to demonstrate a potential insecticidal effect of lemongrass oil in the concentrations of 10, 30 and 50 µL/mL against Musca domestica and Lucilia cuprina and the potentiation of this effect when nanoemulsified this oil against L. cuprina.

Pimpinella anisum Essential Oil Nanoemulsion Toxicity against Tribolium castaneum? Shedding Light on Its Interactions with Aspartate Aminotransferase and Alanine Aminotransferase by Molecular Docking

The insecticidal activity is the result of a series of complex interactions between toxic substances as ligands and insect’s enzymes as targets. Actually, synthetic insecticides used in pest control programs are harmful to the environment and may affect non-target organisms; thus, the use of natural products as pest control agents can be very attractive. In the present work, the toxic effect of aniseed (Pimpinella anisum L.) essential oil (EO) and its nanoemulsion (NE) against the red flour beetle Tribolium castaneum, has been evaluated. To assess the EO mode of action, the impact of sub-lethal concentrations of aniseed EO and NE was evaluated on enzymatic and macromolecular parameters of the beetles, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), total protein, total lipids and glucose. Finally, a molecular docking study was conducted to predict the mode of action of the major EO and NE components namely E-anethole, Limonene, alpha-himalachalene, trans-Verbenol and Linalool at binding site of the enzymes AST and ALT. Herein, the binding location of the main compounds in both proteins are discussed suggesting the possible interactions between the considered enzymes and ligands. The obtained results open new horizons to understand the evolution and response of insect-plant compounds interactions and their effect predicted at the molecular levels and side effects of both animal and human.

[Protection by some plant methanol extracts of cherry tomatoes (Solanum lycopersicum var. Cerasiforme) from fungic infection by Alternaria alternata]

Cherry tomato is very susceptible to fungal infections that can cause considerable damage in crops and during storage. Alternaria infection is one of the most common and dangerous alterations for this fruit. They are caused by Alternaria alternata or some other species belonging to the same genus. In this work, we tested the antifungal activity of methanol extracts from five plants harvested in the region of Jijel (Algeria) on A. alternata. The activity was first tested in vitro and then on greenhouse cherry tomato plants: extracts were applied to healthy plants before infection in order to test their preventive action, and after infection to determine whether they are able to knock out Alternaria. Results showed that Rosmarinus officinalis and Lavandula angustifolia extracts were the most active in vitro on A. alternata. Microscopic observations of the mold indicated that these extracts inhibited the dictyospores production. The antifungal activity tested on the plants grown in greenhouse revealed that R. officinalis extract still was the most active. Extracts of L. angustifolia and Punica granatum did not protect the plants from Alternaria infection, but provided a total cure at the end of the treatment. Extracts from Quercus suber and Eucalyptus globulus were the least active. They did not bestow any protection nor complete healing of the plants. Dictyospores counting on fruits at the end of the treatment confirmed the results obtained for the greenhouse crops.

Biodegradation of slop oil by endophytic Bacillus cereus EN18 coupled with lipase from Rhizomucor miehei (Palatase®)

Removal of slop oil, a by-product of oil refining, also obtained in cleaning up of oil tanks and filters is a difficult issue. High content of hydrocarbons (C3-C40) and other organic compounds makes this waste difficult to eliminate from the environment. The purpose of this investigation was to combine bacterial degradation by endophytic Bacillus cereus EN18 with biotransformation performed using lipase enzyme preparation (Palatase®) to remove recalcitrant compounds present in slop oil from the environment. Endophytic B. cereus EN18 was able to biodegrade up to 40% of slop oil while supplementation with lipase improved the efficiency of contamination removal in about one third. Also the use of lipase enzyme preparation resulted in higher microbial activity of B. cereus EN18 bacterial strain, as well as higher concentration of fatty acids in the culture medium, which indicates higher degradation efficiency. Obtained results suggest that lipase preparation from Rhizomucor miehei (Palatase®) may be a useful agent to improve microbial degradation of recalcitrant pollutants, like slop oil in water environments. GC and spectrometric analysis revealed that hydrocarbons from slop oil were effectively degraded while using both microbial degradation and lipase catalysis.

Nanotechnology in agriculture: Current status, challenges and future opportunities

Nanotechnology has shown promising potential to promote sustainable agriculture. This article reviews the recent developments on applications of nanotechnology in agriculture including crop production and protection with emphasis on nanofertilizers, nanopesticides, nanobiosensors and nano-enabled remediation strategies for contaminated soils. Nanomaterials play an important role regarding the fate, mobility and toxicity of soil pollutants and are essential part of different biotic and abiotic remediation strategies. Efficiency and fate of nanomaterials is strongly dictated by their properties and interactions with soil constituents which is also critically discussed in this review. Investigations into the remediation applications and fate of nanoparticles in soil remain scarce and are mostly limited to laboratory studies. Once entered in the soil system, nanomaterials may affect the soil quality and plant growth which is discussed in context of their effects on nutrient release in target soils, soil biota, soil organic matter and plant morphological and physiological responses. The mechanisms involved in uptake and translocation of nanomaterials within plants and associated defense mechanisms have also been discussed. Future research directions have been identified to promote the research into sustainable development of nano-enabled agriculture.