Plant extracts for developing mosquito larvicides: From laboratory to the field, with insights on the modes of action (2025)

Essential Oil Compositions of Three Invasive Conyza Species Collected in Vietnam and Their Larvicidal Activities against Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus

Molecules

Mosquito-borne infectious diseases are a persistent problem in tropical regions of the world, including Southeast Asia. Vector control has relied principally on synthetic insecticides, but these have detrimental environmental effects and there is an increasing demand for plant-based agents to control insect pests. Invasive weedy plant species may be able to serve as readily available sources of essential oils, some of which may be useful as larvicidal agents for control of mosquito populations. We hypothesize that members of the genus Conyza (Asteraceae) may produce essential oils that may have mosquito larvicidal properties. The essential oils from the aerial parts of Conyza bonariensis, C. canadensis, and C. sumatrensis were obtained by hydrodistillation, analyzed by gas chromatography–mass spectrometry, and screened for mosquito larvicidal activity against Aedes aegypti, Ae. albopictus and Culex quinquefasciatus. The essential oils of C. canadensis and C. sumatrensis, both rich i...

Toxicity of essential oils obtained from Juniperus thurifera var. africana and Mentha suaveolens subsp. timija chemotypes against pre-adult stages of Hyalomma aegyptium tick (Acari: Ixodidae)

Natural Product Research

This experiment was undertaken to compare the acaricidal activity of two essential oil chemotypes obtained from Mint Timija (Mentha suaveolens subsp. timija (Briq.) Harley) and Incense Juniper (Juniperus thurifera var. africana Maire) against immature stages of Hyalomma aegyptium ticks. The results showed that both chemotypes obtained from the two species presented interesting acaricidal activity. The pulegone and menthone-rich chemotype of Mint Timija (CM1) presented the highest toxic activity, particularly against eggs (LD 50 = 17.93 and LD 90 = 36.54 ppm) and larvae (LD 50 = 0.03 and LD 90 = 2.29 ppm). While the piperitone-rich Mint Timija EO (CM2) presented the weakest activity (LD 50 = 51.13 and LD 90 = 83.66 ppm for eggs, LD 50 = 7.84 and LD 90 = 21.03 ppm for larvae). Regarding Incense Juniper, the two chemotypes presented relatively moderate activity, with that of sabinene-rich oil (CJ2) being the most effective against eggs (LD 50 = 22.29 and LD 90 = 53.11 ppm).

Chemical Composition and Broad-Spectrum Insecticidal Activity of the Flower Essential Oil from an Ancient Sicilian Food Plant, Ridolfia segetum

Agriculture

Several species of the family Apiaceae are aromatic herbs that produce essential oils usable on an industrial scale for pharmaceutical, cosmetic, and food purposes. In particular, some essential oils, such as green insecticides for example, may replace synthetic insecticides, keeping most of their efficacy and avoiding environmental pollution or human poisoning. In the present study, we explored the insecticidal potential of Ridolfia segetum (L.) Moris essential oil (EO) against three different pests: Culex quinquefasciatus Say, Musca domestica L., and Spodoptera littoralis (Boisduval). For this purpose, the EO was obtained by hydrodistillation of flowers and its composition was achieved by gas chromatography/flame ionization detection (GC/FID) and gas chromatography/mass spectrometry (GC/MS). This EO was rich in α-phellandrene (49.3%), β-phellandrene (9.2%), terpinolene (20.7%), and piperitenone oxide (5.9%). Concerning the mosquitocidal efficacy, the EO showed noteworthy toxicity ...

Larvicidal activity of Ocimum campechianum, Ocotea quixos and Piper aduncum essential oils against Aedes aegypti

Parasite

Aedes aegypti, the main arbovirus vector of the Yellow fever, Dengue, Chikungunya and Zika viruses, is widely distributed in tropical and subtropical areas throughout the world. Preventive control efforts have been implemented worldwide aimed at reducing its impact on human health. The recent reduction of chemicals available for vector control due to their negative impact on the environment and human health and the increase in mosquito resistance to insecticides have driven the research community to identify and evaluate sustainable alternatives to synthetic insecticides. In this study, the potential larvicidal effect of essential oils extracted from Ocimum campechianum, Ocotea quixos and Piper aduncum were tested in vitro. GC and GC–MS analyses showed that the main compounds were eugenol (18%), 1,8-cineole (39%) and dillapiole (48%), respectively. Susceptibility to essential oils was measured according to the WHO protocol. After 24 h, the mean percentage mortality ranged from 2.7 t...

Efficacy of Antimicrobial and Larvicidal Activities of Green Synthesized Silver Nanoparticles Using Leaf Extract of Plumbago auriculata Lam

Plants

This work reports the synthesis of silver nanoparticles (AgNPs) using aqueous extract of Plumbago auriculata, and evaluates their antibacterial and larvicidal activities. The synthesized silver nanoparticles were characterized by various spectroscopy techniques, such as FTIR, XRD, TEM, EDX, Zeta potential, and DLS. The synthesized AgNPs exhibited significant antibacterial activity against Gram-positive and Gram-negative bacteria, such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae. Furthermore, synthesized nanoparticles inhibited the fourth instars larvae of Aedes aegypti and Culex quinquefasciatus at the concentration of 45.1 and 41.1 µg/mL respectively. Results of dose-dependent studies showed that synthesized nanoparticles were also effective at low concentrations. Molecular docking studies performed with the salivary protein and odorant-binding protein of Aedes aegypti and Culex quinquefasciatus demonstrated that the naphthoquinone compo...

Exploring the Insecticidal Potential of Boldo (Peumus boldus) Essential Oil: Toxicity to Pests and Vectors and Non-target Impact on the Microcrustacean Daphnia magna

Molecules

Every year Chile exports about 2000 tons of boldo folium (Peumus boldus), which is used around the world as a traditional herbal medicinal product (THMP), mostly to relieve gastrointestinal disorders. This biomass may be a resource for the agrochemical industry to manufacture botanical insecticides. In this regard, the insecticidal potential of boldo has been poorly investigated. In the present work, hydrodistillation of a commercial boldo folium gave 1.5% (w/w) of a yellowish essential oil (boldo essential oil, BEO) containing 1,8-cineole (20.7%), p-cymene (18.5%), limonene (9.1%), ascaridole (9.1%) and β-phellandrene (6.4%) as the main constituents, as determined by gas chromatography-mass spectrometry (GC-MS). NMR analysis allowed us to determine that ascaridole was mainly represented by the cis-isomer. BEO was toxic to larvae of the filariasis vector Culex quinquefasciatus and adults of the housefly Musca domestica, showing LC50/LD50 values of 67.9 mg·L−1 and 98.5 µg·adult−1, re...

Developing a Highly Stable Carlina acaulis Essential Oil Nanoemulsion for Managing Lobesia botrana

Nanomaterials

The growing interest in the development of green pest management strategies is leading to the exploitation of essential oils (EOs) as promising botanical pesticides. In this respect, nanotechnology could efficiently support the use of EOs through their encapsulation into stable nanoformulations, such as nanoemulsions (NEs), to improve their stability and efficacy. This technology assures the improvement of the chemical stability, hydrophilicity, and environmental persistence of EOs, giving an added value for the fabrication of natural insecticides effective against a wide spectrum of insect vectors and pests of public and agronomical importance. Carlina acaulis (Asteraceae) root EO has been recently proposed as a promising ingredient of a new generation of botanical insecticides. In the present study, a highly stable C. acaulis-based NE was developed. Interestingly, such a nanosystem was able to encapsulate 6% (w/w) of C. acaulis EO, showing a mean diameter of around 140 nm and a SO...

Ovicidal, pupicidal and bactericidal effects of aminopyridinium-based ionic liquids on Culex pipiens and certain human pathogenic bacteria

Journal of Taibah University for Science

Culex pipiens (Diptera: Culicidae) is one of the most prevalent mosquitoes particularly in the Al-Madinah Al-Munawwarah region, Kingdom of Saudi Arabia, transmitting numerous diseases such as arboviruses, avian malaria, elephantiasis, dirofilariasis, and encephalitis. Worldwide, Culex pipiens has developed resistance to numerous insecticides; therefore, considerable efforts have been done to introduce new mosquito control candidates. Due to their unique physical, biological, and eco-friendly properties, ionic liquids (ILs) have been recently considered as promising agents in controlling a variety of organisms. Six aminopyridinium-based ionic liquids (IL1-IL6) were assayed against eggs and pupae of C. pipiens. Percentages of non-hatched eggs, nonemerged pupae, the lethal concentrations (LC 50 and LC 90) of both C. pipiens eggs and pupae were recorded. after exposure, to different ILs. The effects of ILs against eggs and pupae were concentration and IL-dependant. The percentages of egg unhatchability were much higher than those of pupal mortality, as the percentage of egg unhatchability reached 99% after treatment with IL6 at 0.5 g/L, while the percentage of pupal mortality reached 40.8% after treatment with IL4 at 0.5 g/L. The LC 50 and LC 90 of ILs against pupae were much higher than those of ILs against eggs. Effects of ILs on Staphylococcus aureus (Bacillales: Staphylococcaceae) and Escherichia coli (Entrobacterales: Entrobacteriaceae) were also studied; some ILs showed a considerable effect on both bacteria species. This is the first study to show the ovicidal, pupicidal, and bactericidal effects of aminopyridinium-based ILs in controlling C. pipiens, S. aureus, and E. coli.

Chemical Composition, Antifungal and Insecticidal Activities of the Essential Oils from Tunisian Clinopodium nepeta subsp. nepeta and Clinopodium nepeta subsp. glandulosum

2020

The present investigation was focused on the study of the chemical composition variability and biological activities of the essential oils from Clinopodium nepeta subsp. nepeta and subsp. glandulosum. Essential oils extraction was performed using hydrodistillation and the separation of the constituents was carried out by gas chromatography coupled with mass spectrometry (GC-MS). Antifungal activities were tested against Aspergillus flavus, Aspergillus terreus, Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes, and Candida albicans. Toxicity and repellency were evaluated against the stored product pests Tribolium confusum and Sitophilus zeamais. Both essential oils were characterized by a high content of oxygenated monoterpenes. Piperitone ranks first in the subspecies nepeta and piperitenone oxide is the dominant constituent in the subspecies glandulosum. All tested samples displayed noteworthy antifungal properties, with the highest activity observed for the essen...

High larvicidal efficacy of yeast-encapsulated orange oil against Aedes aegypti strains from Brazil

Parasites & Vectors, 2021

Background Botanical substances such as essential oils (EOs) have demonstrated insecticidal properties and are a valid option for vector control. However, free EOs are unreliable as mosquito larvicides due their easy degradation by environmental exposure to ultraviolet light and higher temperatures. Here, we assessed the efficacy of a mosquito larvicide based on orange oil in a yeast-based delivery system against Aedes aegypti strains with different resistance status towards chemical neurotoxic insecticides. This larvicide preparation was physicochemically characterized in a previous report. Methods Larvae of four Ae. aegypti strains from different regions of Brazil and different resistance profiles for deltamethrin (pyrethroid) and temephos (organophosphate) were tested against yeast-encapsulated orange oil (YEOO) in laboratory conditions for measurement of LC 50 and LC 90 values. The same assays were performed with the Belo Horizonte strain under environmental conditions (natural ...

Phytochemistry, Pharmacological Properties, and Recent Applications of Ficus benghalensis and Ficus religiosa

Plants

Ficus is one of the largest genera in the plant kingdom that belongs to the Moraceae family. This review aimed to summarize the medicinal uses, phytochemistry, and pharmacological actions of two major species from this genus, namely Ficus benghalensis and Ficus religiosa. These species can be found abundantly in most Asian countries, including Malaysia. The chemical analysis report has shown that Ficus species contained a wide range of phytoconstituents, including phenols, flavonoids, alkaloids, tannins, saponins, terpenoids, glycosides, sugar, protein, essential and volatile oils, and steroids. Existing studies on the pharmacological functions have revealed that the observed Ficus species possessed a broad range of biological properties, including antioxidants, antidiabetic, anti-inflammatory, anticancer, antitumor and antiproliferative, antimutagenic, antimicrobial, anti-helminthic, hepatoprotective, wound healing, anticoagulant, immunomodulatory activities, antistress, toxicity s...

Efficacy of Two Monoterpenoids, Carvacrol and Thymol, and Their Combinations against Eggs and Larvae of the West Nile Vector Culex pipiens

Molecules

Background: Insect vector control is facing the challenges of resistance development and environmental hazards caused by synthetic pesticides. This has led to a considerable market opportunity for botanical insecticides. In this scenario, our study investigated the potential of selected bioactive monoterpenoids, carvacrol and thymol, as safe and effective tools to control the West Nile vector Culex pipiens. Furthermore, the combined effect of thymol-carvacrol mixtures and their possible interactions were assessed. Methods: For determining larvicidal and ovicidal 50% lethal concentration (LC50), each monoterpenoid was tested at different concentrations (5–500 mg/L). Then, the fixed ratio method was used for evaluating their combinational efficacy. Results: Carvacrol was more toxic against larvae of Cx. pipiens, with a LC50 value of 14 mg/L, whereas thymol exhibited a LC50 value of 49 mg/L. Comparable trends of efficacy were observed when toxicity on Cx. pipiens eggs was investigated,...

Radiation-Assisted Green Synthesis and Characterization of Selenium Nanoparticles, and Larvicidal Effects on Culex pipiens complex

Journal of Cluster Science

Many environmental hazards are due to chemical insecticides and enhance mosquito species' resistance. This problem is solved by using safer nanocides that reduce environmental pollution among integrated pest management (IPM) programs. Selenium nanoparticles (SeNPs) were green synthesized using Cupressus sempervirens, microwave (MW), and gamma irradiation (G) methods. Synthesized-SeNPs were characterized using UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Dynamic light scattering (DLS), X-ray diffraction (XRD), Zeta potential analysis, and Transmission electron microscopy (TEM). Characterization revealed stable spherical particles with size 11-55 nm for SeNPs-MW (20 min) and 21-75 nm for SeNPs-G (40 KGy). Gamma and microwave irradiations play significant roles in increasing SeNPs yield and decreasing their size. The accumulative mortality of Culex pipiens complex larvae for SeNPs-MW and SeNPs-G at LC50 were 28.25 mg/L and 31.28 mg/L. The accumulated selenium concentration was increased in SeNPs-G treated larvae and measured with inductively coupled plasma mass spectrometry (ICP-MS). Ultrastructural study of the integument using TEM and light microscopy examination of midgut showed clear penetration and accumulation of SeNPs in exoskeleton and several deteriorations in epithelial cells. The results highlighted the important role of gamma and microwave irradiation with plant extract in synthesis and stabilization of SeNPs and their insecticidal efficacy against mosquitoes.

Encapsulation of Carlina acaulis essential oil and carlina oxide to develop long-lasting mosquito larvicides: microemulsions versus nanoemulsions

Journal of Pest Science, 2021

Carlina acaulis root essential oil (EO) is one of the most potent mosquito larvicides (LC50 90%). Poor water solubility and rapid degradation from UV light and oxygen in the environment limit the real-world use of this EO. Herein, we developed nanocarrier-based formulations, namely micro- and nanoemulsions (ME and NE, respectively) containing C. acaulis EO or carlina oxide (both at 0.5%) as active ingredients (a.i.). The larvicidal activity of ME and NE was evaluated against Culex quinquefasciatus. The highest larvicidal activity was achieved by the ME containing 0.5% of the EO (M1); its LC50(90) was 579.1 (791.3) µL L−1. Sublethal effects of this ME and its a.i. were assessed testing both at the LC16, LC30, LC50 and LC90 on mosquito larvae exposed to each product for 1–7 h, and then monitoring mortality for 18 days. At variance with the EO, ME application, even at LC16, led to 100% mortality at 18 days. The EO and its encapsulated form were scarcely toxic to human keratinocytes (H...

Larvicidal Activities and Synergistic Effects of Essential Oils against Anopheles funestus and Culex quinquefasciatus (Diptera: Culicidae) from Kisumu, Kenya

Psyche: A Journal of Entomology, 2022

Rapid development of resistance in vector mosquitoes to synthetic insecticides is a major challenge for malaria control. The use of plant-derived essential oils (EOs) is an attractive strategy in controlling mosquito populations because they are environmentally safe and may have a lower chance of developing resistance. This study assessed the larvicidal activities of EOs from Lantana camara, Lippia multiflora, Lippia chevalieri, and Cymbopogon schoenanthus against Anopheles funestus and Culex quinquefasciatus. The 3rd–4th instar larvae were tested using a World Health Organization (WHO)-modified protocol to evaluate larval mortality 24 h after exposure to EOs and their binary combinations. Culex quinquefasciatus larvae were more susceptible to EOs than An. funestus larvae. For Cx. quinquefasciatus, the lethal concentrations at 50% mortality (LC50s) of EOs from C. schoenanthus, L. multiflora, L. camara, and L. chevalieri were 23.32, 27.24, 38.54, and 54.11 ppm, respectively; whereas ...

Molecular action of larvicidal flavonoids on ecdysteroidogenic glutathione S-transferase Noppera-bo in Aedes aegypti

BMC Biology

Background Mosquito control is a crucial global issue for protecting the human community from mosquito-borne diseases. There is an urgent need for the development of selective and safe reagents for mosquito control. Flavonoids, a group of chemical substances with variable phenolic structures, such as daidzein, have been suggested as potential mosquito larvicides with less risk to the environment. However, the mode of mosquito larvicidal action of flavonoids has not been elucidated. Results Here, we report that several flavonoids, including daidzein, inhibit the activity of glutathione S-transferase Noppera-bo (Nobo), an enzyme used for the biosynthesis of the insect steroid hormone ecdysone, in the yellow fever mosquito Aedes aegypti. The crystal structure of the Nobo protein of Ae. aegypti (AeNobo) complexed with the flavonoids and its molecular dynamics simulation revealed that Glu113 forms a hydrogen bond with the flavonoid inhibitors. Consistent with this observation, substituti...

Essential Oils from Cameroonian Aromatic Plants as Effective Insecticides against Mosquitoes, Houseflies, and Moths

Plants

Recently, spices have attracted the attention of scientists and agrochemical companies for their potential as insecticidal and acaricidal agents, and even as repellents to replace synthetic compounds that are labeled with detrimental impacts on environment and human and animal health. In this framework, the aim of this study was to evaluate the insecticidal potential of the essential oils (EOs) obtained from three Cameroonian aromatic plants, namely Monodora myristica (Gaertn.) Dunal, Xylopia aethiopica (Dunal) A. Rich., and Aframomum citratum (J. Pereira) K. Schum. They were produced by hydrodistillation, with yields of 3.84, 4.89, and 0.85%, respectively. The chemical composition was evaluated by GC-MS analysis. The EOs and their major constituents (i.e., geraniol, sabinene, α-pinene, p-cymene, α-phellandrene, and β-pinene) were tested against the polyphagous moth pest, i.e., Spodoptera littoralis (Boisd.), the common housefly, Musca domestica L., and the filariasis and arbovirus ...

Essential oils from three Algerian medicinal plants (Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides) as new botanical insecticides?

Environmental Science and Pollution Research, 2020

Medicinal and aromatic plants represent an outstanding source of green active ingredients for a broad range of real-world applications. In the present study, we investigated the insecticidal potential of the essential oils obtained from three medicinal and aromatic plants of economic importance in Algeria, Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides. Gas chromatography coupled with mass spectrometry (GC-MS) was used to study the essential oil chemical compositions. The three essential oils were tested against a mosquito vectoring filariasis and arboviruses, i.e., Culex quinquefasciatus, a fly pest acting also as pathogens vector, Musca domestica, and an agricultural moth pest, i.e., Spodoptera littoralis, using WHO and topical application methods, respectively. The essential oil from A. campestris, containing β-pinene (15.2%), α-pinene (11.2%), myrcene (10.3%), germacrene D (9.0%) (Z)-β-ocimene (8.1%) and γ-curcumene (6.4%), showed remarkable toxicity against C. quinquefasciatus (LC 50 of 45.8 mg L −1) and moderate effects (LD 50 of 99.8 μg adult −1) against M. domestica. Those from P. arabica and S. satureioides, containing epi-α-cadinol (23.9%), δ-cadinene (21.1%), α-cadinol (19.8%) and germacrene D-4-ol (8.4%), and thymol (25.6%), α-terpineol (24.6%), borneol (17.4%) and p-cymene (11.4%), respectively, were more active on S. littoralis showing LD 50 values of 68.9 and 61.2 μg larva −1 , respectively. Based on our results, the essential oil from A. campestris may be further considered a candidate ingredient for developing botanical larvicides.

Environmental safety and mode of action of a novel curcumin-based photolarvicide

Environmental Science and Pollution Research, 2020

Aedes aegypti is the vector of important diseases like dengue, zika, chikungunya, and yellow fever. Vector control is pivotal in combating the spread of these mosquito-borne illnesses. Photoactivable larvicide curcumin obtained from Curcuma longa Linnaeus has shown high potential for Ae. aegypti larvae control. However, the toxicity of this photosensitizer (PS) might jeopardize non-target aquatic organisms. The aim of this study was to evaluate the toxicity of this PS to Daphnia magna and Danio rerio, besides assessing its mode of action through larvae biochemical and histological studies. Three PS formulations were tested: PS in ethanol+DMSO, PS in sucrose, and PS in D-mannitol. The LC 50 of PS in ethanol+DMSO to D. rerio was 5.9 mg L −1 , while in D. magna the solvents were extremely toxic, and LC 50 was not estimated. The PS formulations in sugars were not toxic to neither of the organisms. Reactive oxygen species (ROS) were generated in D. magna exposed to 50 mg L −1 of PS in D-mannitol, and D. rerio did not elicit this kind of response. D. magna feeding rates were not affected by the PS in Dmannitol. Concerning Ae. aegypti larvae, there were changes in reduced glutathione and protein levels, while catalase activity remained stable after exposure to PS in D-mannitol and sunlight. Histological changes were observed in larvae exposed to PS in sucrose and D-mannitol, most of them irreversible and deleterious. Our results show the feasibility of this photolarvicide use in Ae. aegypti larvae control and its safety to non-target organisms. These data are crucial to this original vector control approach implementation in public health policies.

Medicinal Plants of Solanum Species: The Promising Sources of Phyto-Insecticidal Compounds

Journal of Tropical Medicine

Several medicinal plants have the potential to be a promising alternative pharmacological therapy for a variety of human illnesses. Many insects, including mosquitoes, are important vectors of deadly pathogens and parasites, which in the world’s growing human and animal populations can cause serious epidemics and pandemics. Medicinal plants continue to provide a large library of phytochemicals, which can be used to replace chemically synthesized insecticides, and utilization of herbal product-based insecticides is one of the best and safest alternatives for mosquito control. Identifying new effective phyto-derived insecticides is important to counter increasing insect resistance to synthetic compounds and provide a safer environment. Solanum genus (Solanaceae family or nightshades) comprises more than 2500 species, which are widely used as food and traditional medicine. All research publications on insecticidal properties of Solanaceae plants and their phytoconstituents against mosq...

Larvicidal effect from different Annonaceae species on Culex quinquefasciatus

Environmental Science and Pollution Research, 2020

The recent outbreaks of mosquito-borne diseases highlighted the pivotal importance of mosquito vector control in tropical areas worldwide. Several strategies have been developed to control vector populations and disease transmission in endemic areas. The steps to obtain natural active compounds involve the pre-selection in a biological model and subsequently evaluation on specific models. The present study reports the evaluation of 35 extracts, fractions, and essential oils obtained from five species from the Annonaceae family on Artemia salina and Culex quinquefasciatus. The A. salina results were used as a pre-screening for larvicidal test about mosquitoes. A correlation of biological activity in both bioassays was observed for the hydroethanolic extracts and their respective hexane and chloroform fractions of the leaves of Annona species, except A. nutans. The same correlation was also observed for all tested essential oils and petroleum ether extracts from Duguetia species. It was possible to limit an interval of lethality about A. salina, which has a corresponding range to the larvicidal test against the mosquito. The main components present in D. lanceolata essential oil or enriched fraction were α-selinene, aristolochene, (E)-caryophyllene, and (E)calamenene. For D. furfuracea, the main components present of the underground parts were (E)-asarone, 2,4,5trimethoxystyrene, spathulenol, and bicyclogermacrene for aerial parts. The A. salina test could be used as a model for the pre-screening of larvicidal activity.

Impregnation of pectin-cedarwood essential oil nanocapsules onto mini cotton bag improves larvicidal performances

Scientific Reports, 2020

The use pesticide is one of the indispensable means to combat mosquito borne diseases. However, the repeated use of synthetic pesticides has induced resistance in the vector pest along with undesirable impact on the environment. The biodegradability, non-persistent and user’s safety are the root cause to prefer plant-derived pesticides to synthetic ones. The botanical based pesticides tend to degrade rapidly under the influence of several environmental factors. For the feasible application as pesticides, the plant products are formulated either as liquid or as purely solid. Despite well-established formulation technology in pesticide delivery, their handling trouble is being ignored. There is difficulty in liquid formulation of pesticide products, as they are prone to splashing and spillage, resulting in contamination, wastage and direct exposure to skin; whereas a solid formulation tends to produce dust. In the present work, cedarwood (Cedrus deodara) essential oil embedded pectin ...

Encapsulation of sea fennel (Crithmum maritimum) essential oil in nanoemulsion and SiO2 nanoparticles for treatment of the crop pest Spodoptera litura and the dengue vector Aedes aegypti

Industrial Crops and Products, 2020

Crithmum maritimum L. (Apiaceae), also known as sea fennel, is a halophythe plant colonizing cliffs and coastal dunes and pebble of the Mediterranean sea and Atlantic ocean. Based on previous reports, this herb produces an essential oil endowed with insecticidal effects against various pests and insect vectors. In the present work, we investigated the insecticidal effectiveness of the seed essential oil and its encapsulated forms (nanoemulsion and SiO 2 nanoparticles, SiNPs) against larvae of the mosquito Aedes aegypti and cotton leafworm Spodoptera litura, in terms of larval contact toxicity and reduction of adult longevity and fecundity. The essential oil composition was characterized by the phenylpropanoids dillapiole and myristicin and oxygenated monoterpenes γ-terpinene and thymol methyl ether. Based on the insecticidal assays, we noticed that all developed products, namely sea fennel essential oil, nanoemulsion and encapsulated silica nanoparticles, showed significant toxicity against larvae and pupae of Ae. aegypti and S. litura. Notably, the SiNPs showed LC 50 values ranging from 8.823 (I instar) to 17.911 μL/L (pupa) on Ae. aegypti (I instar-pupa) and from 24.610 (I instar) to 64.546 μL/L (pupa) on S. litura. Furthermore, all three selected bioinsecticides reduced longevity and fecundity in both targets. Overall the sea fennel essential oil and its encapsulated forms, i.e. nanoemulsion and SiNPs, are promising alternatives for the control of insects causing human diseases and damages in agriculture.

Insecticidal activity of essential oils from American native plants against Aedes aegypti (Diptera: Culicidae): an introduction to their possible mechanism of action

Scientific Reports, 2023

Searching for new bioactive molecules to design insecticides is a complex process since pesticides should be highly selective, active against the vector, and bio-safe for humans. Aiming to find natural compounds for mosquito control, we evaluated the insecticidal activity of essential oils (EOs) from 20 American native plants against Aedes aegypti larvae using bioassay, biochemical, and in silico analyses. The highest larvicide activity was exhibited by EOs from Steiractinia aspera (LC 50 = 42.4 µg/ mL), Turnera diffusa (LC 50 = 70.9 µg/mL), Piper aduncum (LC 50 = 55.8 µg/mL), Lippia origanoides (chemotype thymol/carvacrol) (LC 50 = 61.9 µg/mL), L. origanoides (chemotype carvacrol/thymol) (LC 50 = 59.8 µg/mL), Hyptis dilatata (LC 50 = 61.1 µg/mL), Elaphandra quinquenervis (LC 50 = 61.1 µg/mL), and Calycolpus moritzianus (LC 50 = 73.29 µg/mL) after 24 h. This biological activity may be related to the disruption of the electron transport chain through the mitochondrial protein complexes. We hypothesized that the observed EOs' effect is due to their major components, where computational approaches such as homology modeling and molecular docking may suggest the possible binding pose of secondary metabolites that inhibit the mitochondrial enzymes and acetylcholinesterase activity (AChE). Our results provided insights into the possible mechanism of action of EOs and their major compounds for new insecticide designs targeting the mitochondria and AChE activity in A. aegypti for effective and safe insecticide. The new way to design green insecticides includes plant extracts (PE) and essential oils (EOs), focusing on environmentally eco-friendly products 1-3. Therefore, it is crucial to begin pesticide design with a selective screening to know if the product is suitable for insect control and then to continue its refinement processes to support a future commercial insecticidal formulation. In this sense, and due to the necessity of discovering new products for mosquito control that are environmentally safe and fit into a philosophy of sustainability from a safety perspective, further findings on bioinsecticides must bring information about the toxicity of their components 3-5. Fortunately, there is extensive documentation about plants with insecticidal activity against A. aegypti, even with comprehensive details on their chemical characterization to make them commercial biopesticides 6-8. Within this extensive documentation, some studies highlight features that should have a botanical insecticide against mosquito larvae. In the first instance, to acquire this connotation, the lethal concentration (LC) LC 50 of EO or PE should be less than 100 ppm, also considering their physicochemical properties 9. Classification for the mechanism of action of insecticide substances has also been described and includes protein denaturalization, enzymatic inhibition, and membrane disintegration 7 .

Chemical Composition and Larvicidal Activity of Lavandula angustifolia Subsp. angustifolia and Lavandula dentata Spp. dentata Essential Oils against Culex pipiens Larvae, Vector of West Nile Virus

Psyche, 2021

e Culex pipiens mosquito (Diptera: Culicidae) is highly suspected to be the vector responsible for the spread of several parasitic and viral diseases. e use of synthetic insecticides is generally the preferred method of controlling these mosquitoes' proliferation. However, it has led to resistance problems in target mosquitoes and environmental damage. Hence, diverse plant extracts could be considered as an alternative and potential source as mosquito control agents. In this study, essential oils of Lavandula angustifolia subsp. angustifolia and Lavandula dentata spp. dentata that are growing in Morocco were examined for their insecticidal effects on Culex pipiens larvae. e bioassay was performed according to a methodology inspired by the standard protocol of the World Health Organization. e mortality rate was determined after 24 hours of exposure, and probit regression analysis was used to calculate LC 50 and LC 90 . e chemical analysis revealed that the principal compounds of L. angustifolia subsp. essential oils include linalool, linalyl acetate, geraniol, lavandulyl acetate, camphor, β-caryophyllene, terpinen-4-ol, β-myrcene, and 1,8-cineole, while the essential oil of L. dentata spp. was mainly composed of 1,8-cineole, camphor, α-pinene, transpinocarveol, linalool, and borneol. ese volatile compounds have shown a toxic effect against Culex pipiens larvae, with lethal concentrations LC 50 and LC 90 being, respectively, 140 µg/ml and 450 µg/ml, for the L. angustifolia subsp. essential oil. Meanwhile, they were estimated at 2670 µg/ml and 7400 µg/ml, respectively, for the L. dentata spp. essential oil. ese results suggest using essential oils of two species of Lavandula to control the Culex pipiens mosquito. It could be useful for the study of new natural larvicidal compounds.