Commercially Available Essential Oil Formulas as Repellents Against the Stored-Product Pest Alphitobius diaperinus

Ethnobotanical uses, phytochemistry and bioactivities of Cymbopogon plants: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Cymbopogon (Poaceae) plants have been used for various purposes by many indigenous peoples in all continents. In particular, almost all species in the genus have traditionally been used as folk medicine to treat ailments. Traditional application records indicated that Cymbopogon might be used extensively to treat cold, dizziness, headache, loss of appetite, abdominal pain, rheumatism, diarrhea, whole grass for cold, sore throat, tracheitis and others.

AIMS OF THE REVIEW

Despite several research confirmed that Cymbopogon includes a range of active components, no review has been undertaken to consolidate information on its traditional uses, phytochemistry, pharmacology, and/or quality control. Thus this article aims to update a comprehensive review about the traditional uses, phytochemistry, pharmacology, cultivation techniques, economic benefits, trade, threats, and future conservation implications of Cymbopogon species. It may provide informative data for future development and further investigation of this important plant group.

MATERIALS AND METHODS

Traditional medicinal books and ethnomedicinal publications related to Cymbopogon from 1992 to 2023 were collated to investigate its ethnobotanical, phytochemical and pharmacological information. The online databases including Google Scholar, SciFinder, Web of Science, Scopus, Springer Link, PubMed, Wiley, China National Knowledge Infrastructure (CNKI), Baidu Scholar, and WanFang Database were screened.

RESULTS

Cymbopogon (Gramineae or Poaceae) plants have been grown worldwide. Traditional Chinese medicine and other medicinal systems believes that Cymbopogon has the effect of relieve a cough, analgesia, treating dizziness, traumatic injury and can relieve abdominal pain. A total of 153 compounds, including flavonoids, terpenoids, fatty acid and other compounds were isolated or identified from Cymbopogon species by phytochemical studies. The extracts or compounds from Cymbopogon have exhibited numerous biological activities such as antibacterial, antiinflammatory, antiviral, antineoplastic, antiarrhythmic, antidiabetic and other activities. The rich contents of citronellal, citronellol and geraniol found in Cymbopogon also provide significant nutritional benefits.

CONCLUSION

Based on their traditional uses, phytochemicals, and pharmacological activities, Cymbopogon plants are potential medicinal and edible resources with diverse pharmacological effects. Due to various advantages of this group, they possess huge application potential in food and pharmaceutical industries, and animal husbandry. Among them, citronella is very important in terms of economic development. Further comprehensive research to evaluate the medicinal properties of Cymbopogon species will be necessary for future development.

Plant secondary metabolites as potential bioinsecticides? Study of the effects of plant-derived volatile organic compounds on the reproduction and behaviour of the pest beetle Tenebrio molitor

Modern agriculture has many environmental consequences, such as soil contamination, accumulation of toxic compounds in the environment or risk of adverse effects on nontarget organisms and for these reasons, scientists are seeking a more environmentally friendly alternative to synthetic insecticides. This study investigated the effects of four plant secondary metabolites classified as volatile organic compounds (VOCs), which have potential as bioinsecticides, (E)-2-decenal, furfural, 2-undecanone and (E,E)-2-4-decadienal, in concentrations 10^-5 and 10^-7 M, on female reproductive processes and larval hatchability of the Tenebrio molitor beetle. Our study indicates proper development of ovaries after application of compounds however the volume of terminal oocytes was significantly reduced, with the strongest effect of (E)- 2-decenal which reduced the volume approximately three times. The relative vitellogenin expression level was reduced, with the strongest effect observed after application of furfural, (E,E)- 2-4-decadienal and (E)- 2-decenal in concentration 10^-7 M, at the same time patency index was significantly reduced up to 2-times after application of furfural at 10^-7 M. What is more important morphological changes translated into physiological ones. The number of laid eggs was affected, with the strongest inhibition after application of furfural (∼43% reduction), (E,E)- 2-4-decadienal (∼33%) and (E)- 2-decenal at concentration 10^-7 M (∼33%). Moreover, we observed up to 13% (in case of 2-undecanone) decrease in larval hatchability. Tested compounds exhibited a repellent effect and caused 60% reduction of insect survivability after (E)- 2-decenal at concentration 10^-5 M. Altogether, VOCs seems like potential bioactive compounds in plant protection.

Advances in mosquito repellents: effectiveness of citronellal derivatives in laboratory and field trials

BACKGROUND

Several essential oils, including citronella (lemongrass, Cymbopogon sp., Poaceae), are well-known mosquito repellents. A drawback of such products is their limited protection time resulting from the high volatility of their active components. In particular, citronella oil protects for <2 h, although formulations with fixatives can increase this time.

RESULTS

We synthesized hydroxylated cyclic acetals of citronellal, the main component of citronella, to obtain derivatives with lower volatility and weaker odour. The crude mixture of isomers obtained in the reaction was tested under laboratory conditions for its repellency against two mosquito species, the major malaria vector Anopheles gambiae and the arbovirus vector Aedes albopictus, and found to be endowed with longer protection time with respect to DEET (N,N-diethyl-meta-toluamide) at the same concentration. Formulated products were tested in a latin square human field trial, in an area at a high density of A. albopictus for 8 h from the application. We found that the performance of the citronellal derivatives mixture is comparable (95% protection for ≤3.5 h) with those of the most widespread synthetic repellents DEET and Icaridin, tested at a four-fold higher doses.

CONCLUSIONS

Modifying the hydrophilicity and volatility of natural repellents is a valuable strategy to design insect repellents with a long-lasting effect. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Utilization of Pomelo (Citrus maxima) Peel Waste into Bioactive Essential Oils: Chemical Composition and Insecticidal Properties

Simple Summary

The disposal of agricultural waste products is an emerging concern and an alternative to this is the development of value-added products from these wastes. Here we extracted the essential oil from Citrus maxima (CMEO) and examined its larvicidal and pest control potentials. Results pointed out that CMEO can be effective biopesticides against two major insect pests of stored grains. Furthermore, CMEO had a significant larvicidal action against different mosquito species. This study provided useful information on the compositional aspects and insecticidal properties of CMEO.

Abstract

The wastes generated during the post-harvest handling of various agricultural commodities is rather under-utlilized. The peels of citrus fruits are often discarded as waste. Citrus peels are rich in essential oils and exhibit toxicity towards various insect species. The essential oils are also an eco-friendly option for insect pest management. The Citrus maxima peel essential oil (CMEO), a waste product, characterized it, and evaluated its potential for insect pest management. The major terpenoids present in CMEO are Limonene and α-Pinene. The CMEO displayed potentials in controlling the insect pests via contact and fumigant toxicity. Moreover, CMEO showed significant larvicidal activities against Culex tritaeniorhynchus and Aedes aegypti species of mosquitoes; however, Armigeres subalbatus was more resistant. The biological safety of the essential oil was also tested against the stored seeds, where no significant inhibition of seed germination was noticed compared to the control. Utilizing a waste product such as citrus peel for pest management can achieve the dual objective of waste utilization and eco-friendly pest management. Overall, the CMEO is therefore found to be a bioactive essential oil extracted from the wastes of pomelo (C. maxima).

Host-Guest Inclusion Complexes of Natural Products and Nanosystems: Applications in the Development of Repellents

Repellents are compounds that prevent direct contact between the hosts and the arthropods that are vectors of diseases. Several studies have described the repellent activities of natural compounds obtained from essential oils. In addition, these chemical constituents have been pointed out as alternatives to conventional synthetic repellents due to their interesting residual protection and low toxicity to the environment. However, these compounds have been reported with short shelf life, in part, due to their volatile nature. Nanoencapsulation provides protection, stability, conservation, and controlled release for several compounds. Here, we review the most commonly used polymeric/lipid nanosystems applied in the encapsulation of small organic molecules obtained from essential oils that possess repellent activity, and we also explore the theoretical aspects related to the intermolecular interactions, thermal stability, and controlled release of the nanoencapsulated bioactive compounds.

Antibacterial Biodegradable Films Based on Alginate with Silver Nanoparticles and Lemongrass Essential Oil-Innovative Packaging for Cheese

Replacing the petroleum-based materials in the food industry is one of the main objectives of the scientists and decision makers worldwide. Biodegradable packaging will help diminish the environmental impact of human activity. Improving such biodegradable packaging materials by adding antimicrobial activity will not only extend the shelf life of foodstuff, but will also eliminate some health hazards associated with food borne diseases, and by diminishing the food spoilage will decrease the food waste. The objective of this research was to obtain innovative antibacterial films based on a biodegradable polymer, namely alginate. Films were characterized by environmental scanning electron microscopy (ESEM), Fourier-transform infrared spectroscopy (FTIR) and microscopy, complex thermal analysis (TG-DSC-FTIR), UV-Vis and fluorescence spectroscopy. Water vapor permeability and swelling behavior were also determined. As antimicrobial agents, we used silver spherical nanoparticles (Ag NPs) and lemongrass essential oil (LGO), which were found to act in a synergic way. The obtained films exhibited strong antibacterial activity against tested strains, two Gram-positive (Bacillus cereus and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Salmonella Typhi). Best results were obtained against Bacillus cereus. The tests indicate that the antimicrobial films can be used as packaging, preserving the color, surface texture, and softness of cheese for 14 days. At the same time, the color of the films changed (darkened) as a function of temperature and light presence, a feature that can be used to monitor the storage conditions for sensitive food.

Biodegradable Alginate Films with ZnO Nanoparticles and Citronella Essential Oil-A Novel Antimicrobial Structure

The petroleum-based materials could be replaced, at least partially, by biodegradable packaging. Adding antimicrobial activity to the new packaging materials can also help improve the shelf life of food and diminish the spoilage. The objective of this research was to obtain a novel antibacterial packaging, based on alginate as biodegradable polymer. The antibacterial activity was induced to the alginate films by adding various amounts of ZnO nanoparticles loaded with citronella (lemongrass) essential oil (CEO). The obtained films were characterized, and antibacterial activity was tested against two Gram-negative (Escherichia coli and Salmonella Typhi) and two Gram-positive (Bacillus cereus and Staphylococcus aureus) bacterial strains. The results suggest the existence of synergy between antibacterial activities of ZnO and CEO against all tested bacterial strains. The obtained films have a good antibacterial coverage, being efficient against several pathogens, the best results being obtained against Bacillus cereus. In addition, the films presented better UV light barrier properties and lower water vapor permeability (WVP) when compared with a simple alginate film. The preliminary tests indicate that the alginate films with ZnO nanoparticles and CEO can be used to successfully preserve the cheese. Therefore, our research evidences the feasibility of using alginate/ZnO/CEO films as antibacterial packaging for cheese in order to extend its shelf life.

Innovative Antimicrobial Chitosan/ZnO/Ag NPs/Citronella Essential Oil Nanocomposite-Potential Coating for Grapes

New packaging materials based on biopolymers are gaining increasing attention due to many advantages like biodegradability or existence of renewable sources. Grouping more antimicrobials agents in the same packaging can create a synergic effect, resulting in either a better antimicrobial activity against a wider spectrum of spoilage agents or a lower required quantity of antimicrobials. In the present work, we obtained a biodegradable antimicrobial film that can be used as packaging material for food. Films based on chitosan as biodegradable polymer, with ZnO and Ag nanoparticles as filler/antimicrobial agents were fabricated by a casting method. The nanoparticles were loaded with citronella essential oil (CEO) in order to enhance the antimicrobial activity of the nanocomposite films. The tests made on Gram-positive, Gram-negative, and fungal strains indicated a broad-spectrum antimicrobial activity, with inhibition diameters of over 30 mm for bacterial strains and over 20 mm for fungal strains. The synergic effect was evidenced by comparing the antimicrobial results with chitosan/ZnO/CEO or chitosan/Ag/CEO simple films. According to the literature and our preliminary studies, these formulations are suitable as coating for fruits. The obtained nanocomposite films presented lower water vapor permeability values when compared with the chitosan control film. The samples were characterized by SEM, fluorescence and UV-Vis spectroscopy, FTIR spectroscopy and microscopy, and thermal analysis.

The Effect of Rosmarinus officinalis Essential Oil Fumigation on Biochemical, Behavioral, and Physiological Parameters of Callosobruchus maculatus

This study explores the influence of rosemary, Rosmarinus officinalis (L.) essential oil (EO) on the biochemical (acetylcholinesterase, catalase, and glutathione S-transferase), physiological (oxygen consumption), and behavioral (open field test, repellency) parameters of an important stored product insect: cowpea weevil, Callosobruchus maculatus (F.). R. officinalis EO exhibited effective insecticidal action against C. maculatus even at relatively low concentrations. LC50 = 15.69 μL/L air, and was highly repellent at concentrations equal to or above LC25. Statistically significant inhibition in locomotor activity occurred only after the acute exposure to the EO at LC12.5 and LC25. The oxygen consumption test showed metabolism increase only at LC50. An increase in activity was observed in the case of all three enzymes examined. The presented data provides a potentially valuable resource in designing more environmentally friendly and safer insecticide agents.

Essential Oils Extracted from Different Species of the Lamiaceae Plant Family as Prospective Bioagents against Several Detrimental Pests

On the basis of the side effects of detrimental synthetic chemicals, introducing healthy, available, and effective bioagents for pest management is critical. Due to this circumstance, several studies have been conducted that evaluate the pesticidal potency of plant-derived essential oils. This review presents the pesticidal efficiency of essential oils isolated from different genera of the Lamiaceae family including Agastache Gronovius, Hyptis Jacquin, Lavandula L., Lepechinia Willdenow, Mentha L., Melissa L., Ocimum L., Origanum L., Perilla L., Perovskia Kar., Phlomis L., Rosmarinus L., Salvia L., Satureja L., Teucrium L., Thymus L., Zataria Boissier, and Zhumeria Rech. Along with acute toxicity, the sublethal effects were illustrated such as repellency, antifeedant activity, and adverse effects on the protein, lipid, and carbohydrate contents, and on the esterase and glutathione S-transferase enzymes. Chemical profiles of the introduced essential oils and the pesticidal effects of their main components have also been documented including terpenes (hydrocarbon monoterpene, monoterpenoid, hydrocarbon sesquiterpene, and sesquiterpenoid) and aliphatic phenylpropanoid. Consequently, the essential oils of the Lamiaceae plant family and their main components, especially monoterpenoid ones with several bioeffects and multiple modes of action against different groups of damaging insects and mites, are considered to be safe, available, and efficient alternatives to the harmful synthetic pesticides.