Strong Larvicidal Activity Research Articles

Investigation on the mosquitocidal property of cis-13-Octadecenoic acid isolated from Andrographis paniculata against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae)

Mosquitoes are a critical global public health concern, causing millions of deaths each year due to the viral infections and diseases they spread. In recent decades, synthetic insecticides and repellents have been used to control mosquito populations and virus transmission, but they often harm the environment and non-target organisms, including humans. This research investigates the isolation, characterization, and structural elucidation of cis-13-Octadecenoic acid derived from Andrographis paniculata, and its effectiveness against the immature stages of Aedes aegypti and Culex quinquefasciatus. The extracts from A. paniculata underwent fractionation, with the most bioactive fractions being further purified and analyzed. Spectroscopic techniques were employed to confirm the structure of cis-13-Octadecenoic acid. Biological assays were then performed to evaluate its ovicidal, larvicidal, and pupicidal activities. cis-13-Octadecenoic acid exhibited notable ovicidal activity, causing 25 % mortality in Ae. aegypti eggs and 29 % mortality in Cx. quinquefasciatus eggs at a concentration of 2 ppm. Additionally, it showed strong larvicidal and pupicidal activities, with LC50 values of 2.67 ppm and 3.39 ppm for Ae. aegypti larvae and pupae, and 3.10 ppm and 2.93 ppm for Cx. quinquefasciatus larvae and pupae, respectively. These findings demonstrate the potential of cis-13-Octadecenoic acid as an effective natural compound for mosquito control, highlighting the broader importance of natural products as alternatives to synthetic insecticides in the management of vector-borne diseases.

Chemical Compositions and Antimicrobial and Mosquito Larvicidal Activities of the Leaf Essential Oils of Goniothalamus yunnanensis W.T.Wang and G. touranensis Ast: Experimental and In Silico Approaches.

The current research describes a phytochemical analysis and antimicrobial activity of essential oils extracted from the leaves of two Vietnamese Annonaceae species Goniothalamus yunnanensis W.T.Wang and G. touranensis Ast. By the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analyses, sesquiterpene hydrocarbons accounted for the highest percentage of 68.22 % in G. yunnanensis leaf essential oil with bicyclogermacrene (31.03 %) and (E)-caryophyllene (21.12 %) being the main compounds. G. touranensis leaf essential oil was dominated by monoterpene hydrocarbons (57.08 %) with p-cymene (19.95 %) and α-pinene (16.82 %) being the major compounds. By the microdilution broth susceptibility assay, two oil samples showed strong antibacterial effects on the Gram-positive bacteria Enterococcus faecalis ATCC51299, Staphylococcus aureus ATCC29213, and Bacillus cereus ATCC11778 with the MIC values of 16-64 μg/mL. They also inhibited the growth of the yeast Candida albicans ATCC 60193 with the same MIC value of 128 μg/mL. From the vector-based intervention approach, both oil samples showed strong mosquito larvicidal activity against four-instar larvae of Aedes aegypti and Ae. albopictus with the 24 h LC50 values of 16.75-27.60 μg/mL and 24 h LC90 values of 24.31-46.18 μg/mL. Docking results indicated that bicyclogermacrene and p-cymene exhibited the highest ΔG (binding affinity) values of -8.208 and -6.799 kcal/mol with the olfactory binding proteins (OBPs) of Ae. aegypti and Ae. albopictus, respectively.

Flavonoids from Mimosa tenuiflora Green Propolis: Chemotaxonomy, Antioxidant, Anti‐Inflammation, Anti‐Bacteria, Mosquito Larvicidal Activity, and In Silico Approach

AbstractPhytochemical study of green propolis alcohol extract of Brazilian Caatinga Mimosa tenuiflora (Willd.) Poir resulted in the separation of six flavonoids, including quercetin 3‐methyl ether (1) and 3,3′‐O‐dimethylquercetin (2), and four flavanones eriodictyol 5‐O‐methyl ether (3), 5,4′‐dihydroxy‐6,7‐dimethoxyflavanone (4), licoflavanone (5), and macarangaflavanone B (6). All these metabolites were first isolated from green propolis and the genus Mimosa. Metabolites 3–4 also established chemotaxonomic significance since they had never been observed in the bean family Fabaceae. Flavones 1–2 showed strong antioxidative activity against DPPH (1,1‐diphenyl‐2‐picryl hydrazyl) radicals with IC50 values of 12.40 and 16.23 μg/mL, respectively. All six isolates showed anti‐inflammatory effects against NO (nitric oxide) production in LPS (lipopolysaccharide)‐stimulated Raw 264.7 cells, in which the activity of flavone 1 was better than the standard dexamethasone (IC50 13.35 μg/mL). Flavonoids 1–3 also strongly controlled the growth of the Gram‐positive bacteria Bacillus subtilis ATCC 6051, and Staphylococcus aureus ATCC 29213 with MIC values of 32–64 μg/mL. Six isolated flavonoids exhibited strong or moderate mosquito larvicidal activity against Aedes aegypti and Ae. albopictus fourth instar larvae with the 24 h LC50 values of 29.62–55.89 μg/mL. By in silico approach, compound 1 was a non‐toxic agent with an LD50 value of 5000 mg/kg.

Larvicidal property and active compound profiling of Annona squamosa leaf extracts against two species of diptera, Aedes aegypti and Anopheles stephensi.

Vector control measures are important in lowering the spread of infections spread by mosquito. Synthetic pesticides used to suppress vector populations during the larval stage have had adverse impacts on people and the environment. The early III instar larvae of Aedes aegypti and Anopheles stephensi were the targets of the current experiment, which assessed the larvicidal ability of petroleum ether, chloroform, methanol, and aqueous extracts of Annona squamosa leaves. Using the standard World Health Organization (WHO) larval bioassay test, leaf extracts were evaluated for their activity against Ae. aegypti and An. stephensi to determine lethal doses. Phytochemical analysis and gas chromatography-mass spectrometry (GC-MS) were carried out to identify larvicidal components in the extract. Further analysis using a scanning electron microscope (SEM) was done to check the extracts toxicity for both mosquito larvae. The larvicidal active components were identified by GC-MS as tetradecanoic acid, cis-vaccenic acid, and 2,4-di-tert-butylphenol etc. Methanol leaf extracts of A. squamosa (ASME) exhibited strong larvicidal activity against the early 3rd instar larvae of Ae. aegypti and An. stephensi with Lethal concentration (LC50) values of 51.450 ppm and 107.121 ppm. Cell damages to the larva post exposure to ASME were examined. This finding showed that the ASME has better larvicidal activity and its components that may be used to kill larvae as larvicides. The extracts toxicity towards damage of midgut of larva further suggests that this plant methanol leaf extracts could be effective in larval growth control approaches.

Chemical Composition, Mosquito Larvicidal and Antimicrobial Activities, and Molecular Docking Study of Essential Oils of Cinnamomum melastomaceum, Neolitsea buisanensis and Uvaria microcarpa from Vietnam.

The leaf oil compositions of two Lauraceae and one Annonaceae plants cultivated in Vietnam were analysed by GC/MS (gas chromatography-mass spectrometry) analysis. The leaf oil of the first Lauraceae plant Cinnamomum melastomaceum contained 34 identified compounds, in which benzyl benzoate (38.5 %), linalool (19.9 %), (E)-caryophyllene (10.5 %), and α-terpineol (6.9 %) were the major compounds. The leaves of the second Lauraceae plant Neolitsea buisanensis gave an oil with the main compounds (E)-β-ocimene (24.0 %), benzyl benzoate (15.8 %), bicyclogermacrene (14.9 %), and (E)-caryophyllene (6.3 %). The leaf oil of the Annonaceae plant Uvaria microcarpa consisted of the principal compounds (E)-caryophyllene (18.0 %), bicyclogermacrene (8.1 %), and δ-elemene (6.1 %). Two Lauraceae oil samples exhibited strong mosquito larvicidal activity against Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus with LC50 and LD90 values of less than 50 μg/mL. The Annonaceae oil sample showed strong antimicrobial activity against the fungus Aspergillus niger ATCC 1015 with the MIC (minimum inhibitory concentration) value of 32 μg/mL. In the docking approach, the major compounds (E)-caryophyllene, bicyclogermacrene, and benzyl benzoate interacted with the mosquito odorant-binding protein 3OGN, whereas (E)-caryophyllene, bicyclogermacrene, and δ-elemene also potentially interacted with the 4ZA5 protein of fungus A. niger.

Anthelmintic Activity of Tanacetum vulgare L. (Leaf and Flower) Extracts against Trichostrongylidae Nematodes in Sheep In Vitro.

Due to the high prevalence of gastrointestinal nematodes in sheep, the growing anthelmintic resistance, and the development of organic farming systems, sustainable alternatives are being sought. One such method is phytotherapy. This study aimed to evaluate the in vitro ovicidal and larvicidal activity of extracts of tansy (Tanacetum vulgare L.) growing in Latvia on gastrointestinal nematodes (Trichostrongylidae) in sheep. The leaves and flowers of the tansy were extracted separately in 70%, 50%, and 30% ethanol and acetone. Six concentrations were prepared from each extract 500 mg/mL, 200 mg/mL, 100 mg/mL, 50 mg/mL, 20 mg/mL, and 10 mg/mL. In vitro egg hatching test and micro-agar larval development test were performed. Extracts of tansy have strong larvicidal activity. The highest percentage of larvae inhibition for most of the extracts was 100%, but for egg inhibition, it was 95.8% for the 200 mg/mL concentration of 50% acetone and 93.3% for the 500 mg/mL concentration of 50% ethanol leaf extracts. All tansy extracts had ovicidal and larvicidal activity against Trichostrongylidae in sheep.

Chemical composition and toxicity of Artemisia herba-alba essential oil against Cydia pomonella L. (Lepidoptera:Tortricidae) under laboratory conditions

The codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) is a destructive pest of apples and pears worldwide. Due to the phytotoxic effect of chemical fumigant on postharvest apple, botanical insecticides are an interesting alternative to synthetic chemical insecticides regarding their low environmental impact. Hence, in the present study, we investigated the chemical composition and fumigant toxicity of Artemisia herba-alba essential oil against the fifth-instar codling moth, under laboratory conditions. In total, 49 compounds were identified by gas chromatography/mass spectrometry. The major constituents determined were dextro-camphor (30.60%), 2,6-dimethyl-1,3,6-heptatriene (26.71%), safranal (7.04%), borneol (3.94%) and eucalyptol (3.47%). A. herba-alba essential oil showed strong larvicidal activity, with minimum lethal concentration LC50 values of 13.49 and 04.45 μl L-1 air at 24 h and 48 h, respectively. The LT50 values at the lowest (1.81 μl L-1 air) and highest oil concentrations (18.18 μl L-1 air) were, in turn, 59.35 to 19.52 h. The obtained results indicated that essential oil of A. herba-alba may have a potential to be developed as a botanical fumigant against the fifth-instar codling moth.

Essential oils of the ginger plants Meistera caudata and Conamomum vietnamense: chemical compositions, antimicrobial, and mosquito larvicidal activities.

The current study describes the chemical identification, antimicrobial, and mosquito larvicidal activities of essential oils from Meistera caudata and Conamomum vietnamense, growing in Vietnam. Essential oils were extracted from the leaves and rhizomes, and characterized by the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. Monoterpenes (33.1-89.2 %) were the main chemical class found in these oils. β-Pinene (30.8 %) and α-pinene (23.8 %) were two major compounds in M.caudata leaf oil. C.vietnamense leaf and rhizome essential oils were dominated by 1,8-cineole (47.9-62.0 %) and limonene (10.3-16.2 %). With the same MIC (minimum inhibitory concentration) value of 25 μg/mL, C.vietnamense leaf and rhizome essential oils strongly inhibited the growth of Gram-positive bacteria Staphylococcus aureus ATCC 29213 and Bacillus subtilis ATCC 6501, respectively. For 24 and 48-h treatments, C.vietnamense leaf essential oil strongly controlled the growth of mosquito Aedes aegypti with the respective LC50 values of 7.67 and 6.73 μg/mL, and the respective LC90 values of 13.37 and 10.83 μg/mL. In the same manner, C.vietnamense rhizome essential oil also showed strong mosquito larvicidal activity against Aedes albopictus with the LC50 values of 12.37 and 12.00 μg/mL, and the LC90 values of 20.56 and 18.58 μg/mL, respectively. C.vietnamense essential essential oils containing a high amount of 1,8-cineole are generally better than M.caudata essential essential oils in both two biological assays.

Antioxidative limonoids from Swietenia macrophylla fruits: Experimental, DFT (Density Functional Theory) approach, and docking study

Phytochemical investigation of the methanol extract of Swietenia macrophylla fruit first led to the isolation of four limonoids seneganolide (1), khayanone (2), khayanolide B (3), and 6-acetoxy-methyl angolensate (4). Compound 3 (IC50 3.18 µg/mL) was better than the positive control ascorbic acid (IC50 7.18 µg/mL) in an antioxidative assay against DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals. Compound 1 showed strong mosquito larvicidal activity against Aedes aegypti with LC50 values of 34.1–44.1 µg/mL and LC90 values of 57.3–65.1 µg/mL for 24 and 48-h exposures. Based on DFT (density functional theory)/B3LYP/6–311G(d,p) method, the SPL-ET (sequential proton loss-electron transfer) antioxidative mechanism is essential for compound 3 in polar solvents, while the HAT antioxidative route is appropriate in weak or non-polar mediums. Methine group at carbon C-6 of this compound exerted the lowest BDE (bond dissociation energy) values of 72.9–73.8 kcal/mol in both four studied mediums gas, benzene, methanol, and water. In the kinetic reactions with HOO•, CH3OO•, and •NO2 radicals, 6-CH also generated the lowest Gibbs free energy of activation ΔG# values of 14.5–24.2 kcal/mol and the highest rate constant K values of 6.068 × 101–1.75 × 106 L/mol.s. A molecular docking (MD) analysis of seneganolide with relevant Ae. aegypti protein targets revealed AChR (acetylcholine receptor), ACE2 (angiotensin converting enzyme 2), and aaNAT (arylalkylamine N-acetyltransferase) to be potential targets of this compound.

Larvicidal activity and docking study of Ramalina complanata and Cladonia verticillaris extracts and secondary metabolites against Aedes aegypti

The Aedes aegypti mosquito is the main vector of the arboviruses that cause Zika, Yellow Fever, Dengue, and Chikungunya, incapacitating diseases that may even be fatal. There are still no vaccines for any of these viruses. Therefore, the only way to contain outbreaks is to control the vector that transmits them. In the present study, we investigated the larvicidal activity of lichen extracts (Ramalina complanata (Sw.) Ach., 1810 and Cladonia verticillaris (Raddi) Fr.), isolating components that were used against larvae of the mosquito A. aegypti. The ether extract from R. complanata exhibited an LC50 = 5.9 µg.ml−1, while a compound isolated from this species, divaricatic acid, had an LC50 = 27.1 µg.ml−1. The acetone extract of C. verticilaris exhibited an LC50 = 17.4 µg.ml−1 and the isolated compound fumarprotocetraric acid (FUM) had an LC50 = 13.6 µg.ml−1. These results demonstrate that extracts and isolated compounds from the two lichen species have strong larvicidal activities. FUM is the most active compound in our investigation. The molecular docking studies of divaricatic acid and FUM demonstrated that they bind to the active site of AaAChE1 in an energetically favorable manner. The TRP286 residue may have contributed to the more pronounced activity of fumarprotocetraric acid compared to divaricatic acid. Other aspects related to the more pronounced activity of fumarprotocetraric acid are its molecular weight and higher solubility. Our results provide evidence of the importance of studying lichen secondary metabolites as natural sources of insecticides and investigating possible interactions with AaAChE1.

Euclasta condylotricha flowers essential oils: A new source of juvenile hormones and its larvicidal activity against Anopheles gambiae s.s. (Diptera: Culicidae).

The essential oil (EO) of plants of the Poaceae family has diverse chemical constituents with several biological properties. But, data on the chemical constituents and toxicity are still unavailable for some species belonging to this family, such as Euclasta condylotricha Steud (Eu. condylotricha). In this study, the chemical composition of the EOs of Eu. condylotricha flowers was evaluated by gas chromatography coupled with mass spectrometry (GC-MS). The EOs larvicidal property was assessed against third instar larvae of three Anopheles gambiae laboratory strains (Kisumu, Acerkis and Kiskdr) according to the WHO standard protocol. The percentage yields of the EOs obtained from hydro distillation of Eu. condylotricha flowers varied 0.070 to 0.097%. Gas Chromatography-Mass Spectrometry (GC-MS) applied to the EOs revealed fifty-five (55) chemical constituents, representing 94.95% to 97.78% of the total essential oils. Although different chemical profiles of the dominant terpenes were observed for each sample, EOs were generally dominated by sesquiterpenoids with juvenile hormones as the major compounds. The primary compounds were juvenile hormone C16 (JH III) (35.97-48.72%), Methyl farnesoate 10,11-diol (18.56-28.73%), tau-Cadinol (18.54%), and β-Eudesmene (12.75-13.46%). Eu. condylotricha EOs showed a strong larvicidal activity with LC50 values ranging from 35.21 to 52.34 ppm after 24 hours of exposition. This study showed that Eu. Condylotricha flowers essential oils are potent sources of juvenile hormones that could be a promising tool for developing an eco-friendly malaria vector control strategy.

Mosquitocidal activities of Chenopodium botrys whole plant n-hexane extract against Culex quinquefasciatus.

This research aimed to investigate various mosquitocidal activities of Chenopodium botrys whole- plant n-hexane extract against Culex quinquefasciatus. The extract showed remarkable larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus. During the larvicidal and pupicidal activities, the 24-hour lethal concentration (LC50) of extract against 2nd instar larvae, 4th instar larvae and pupae were 324.6, 495.6 and 950.8 ppm, respectively. During the CDC (Centers for Disease Control and Prevention) bottle bioassay for adulticidal activity, the median knockdown times (KDT50) at 1.25% concentration was 123.4 minutes. During the filter paper impregnation bioassay for adulticidal activity, the KDT50 value at 0.138 mg/cm2 concentration was 48.6 minutes. The extract was fractionated into 14 fractions through silica gel column chromatography which were then combined into six fractions on the basis of similar retention factor (Rf) value. These fractions were screened for adulticidal activity by applying CDC bottle bioassay. The fraction obtained through 60:40 to 50:50% n-hexanes-chloroform mobile phase with 0.5 Rf value showed 100% adulticidal activity at 0.2% concentration. During oviposition deterrent activity, the highest concentration (1000 ppm) showed 71.3 ± 4.4% effective repellence and 0.6 ± 0.1 oviposition activity index. During adult emergence inhibition activity, the median emergence inhibition (EI50) value was 312.3 ppm. From the outcome of the present investigation, it is concluded that the n-hexane extract of C. botrys whole- plant possesses strong larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus.

Chemical constituents and strong larvicidal activity of Solanum xanthocarpum among selected plants extracts against the malaria, filaria, and dengue vectors.

The role of mosquitoes is instrumental in the transmission of various diseases. Mosquitoe-borne diseases account for a significant share of the global burden of total infectious diseases. Vector control is the principal method for the control of these mosquito-borne diseases. Plant-derived insecticides serve as an effective alternative to chemical insecticides. The present study has been undertaken to assess the larvicidal potential of methanol and petroleum ether extracts of leaves of Solanum xanthocarpum, Parthenium hysterophorus, Manihot esculenta, and Chamaecyparis obtusa. Larvicidal activity was tested against the early four-stage instar larvae of laboratory-reared susceptible strains of the malaria vector, Anopheles stephensi, dengue fever vector, Aedes aegypti, and the lymphatic filariasis vector, Culex quinquefasciatus at 20 to 120 ppm concentrations. Further, liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectroscopy (GC-MS) analyses were carried out to identify the bioactive compounds present in the methanolic leaf extracts of Solanum xanthocarpum for designing a larvicidal product in future. After 72 h of exposure high larvicidal activities were observed in methanolic and petroleum ether leaves extract of S. xanthocarpum against An. stephensi, Ae. aegypti and Cx. quinquefasciatus. The larvicidal activities for methanol and petroleum ether leaf extract of S. xanthocarpum with LC50 = 09.201 and 12.435 ppm and LC90 = 21.578 and 27.418 ppm for An. stephensi; LC50 = 11.450 and 10.026 ppm and LC90 = 26.328 and 22.632 ppm for Ae. aegypti and LC50 = 12.962 and 13.325 ppm and LC90 = 26.731 and 30.409 ppm for Cx. quinquefasciatus, respectively, were found to be most effective. GC-MS analysis revealed 43 compounds, amongst these phytol (13.09%), 3-allyl-2-methoxy phenol (9.55%), (9Z, 12Z)-9, 12-octadecadienoyl chloride (7.93%), linoleic acid (5.45%), alpha-tocospiro B (5.08%) and hexadecanoic acid (4.35%) were identified as major compounds. Present work showed that leaf extracts of S. xanthocarpum are a source of potential natural candidate that possess several phytochemicals which can be explored further for the development of ecologically safer mosquito control products.

Repellency and insecticidal activity of seven Mugwort (Artemisia argyi) essential oils against the malaria vector Anopheles sinensis

Anopheles sinensis is the main vector of malaria with a wide distribution in China and its adjacent countries. The smoke from burning dried mugwort leaves has been commonly used to repel and kill mosquito adults especially in southern Chinese provinces. In this study, the essential oils of mugwort leaves collected from seven provinces in China were extracted by steam distillation and their chemical compositions were analyzed. Among a total of 56–87 chemical constituents confirmed by GC–MS analyses, four compounds, eucalyptol, β-caryophyllene, phytol and caryophyllene oxide, were identified with appearances from all seven distilled essential oils. The effectiveness varied in larvicidal, fumigant and repellent activities against An. sinensis from these seven essential oils with different geographic origins. The essential oil from Hubei province showed the highest larvicidal activity against the 4th instar larvae of An. sinensis, with a median lethal concentration at 40.23 µg/mL. For fumigation toxicity, essential oils from 4 provinces (Gansu, Shandong, Sichuan and Henan) were observed with less than 10 min in knockdown time. The essential oil distilled from Gansu province displayed the highest repellent activity against Anopheles mosquitoes and provided similar level of protection as observed from DEET. Eucalyptol was the most toxic fumigant compound and phytol showed the strongest larvicidal activity among all tested mugwort essential oil constituents.

Bio-efficacy of Soil Actinomycetes and an Isolated Molecule 1,2-Benzenedicarboxylic Acid from Nonomuraea sp. Against Culex quinquefasciatus Say and Aedes aegypti L. Mosquitoes (Diptera: Culicidae).

Vector-borne diseases such as filariasis and dengue that contribute significantly to disease burden, death, poverty, and social frailty are still a major public healthcare problem worldwide. Currently, synthetic chemicals have been used in mosquito control programs. However, repeated use of chemical insecticides causes environmental pollution and harmful effects on non-target organisms. Therefore, alternative ecofriendly sources from biological source are urgently needed to manage mosquitoes. In this respect, the present study was aimed to evaluate mosquito larvicidal and pupicidal activities of 22 crude extracts of soil actinomycetes on Culex quinquefasciatus and Aedes aegypti and to identify the active molecule. Briefly, the crude ethyl acetate extract and fractions were tested at 62.5, 125, 250, and 500ppm and 2.5, 5.0, 7.5, and 10.0ppm concentrations on larval and pupal stages of Cx. quinquefasciatus and Ae. aegypti. The larval and pupal mortality was assessed after 24h of treatment. Among the 22 isolates screened, Nonomuraea sp. VAS-16 exhibited significant larvicidal and pupicidal activities against the tested mosquito species. Among the 18 fractions screened, fraction-6 showed strong larvicidal and pupicidal activities with the LC50 and LC90 values of 9.1, 18.7, 9.82, and 22.85ppm against the larvae and LC50 and LC90 values of 10.5, 23.1, 12.3, and 24.13ppm against the pupae of Cx. quinquefasciatus and Ae. aegypti, respectively. Fascinatingly, the isolated compound 1,2-benzenedicarboxylic acid from fraction-6 at 0.5, 1.0, 1.5, and 2.0ppm concentration recorded lower LC50 and LC90 values of 4.27, 14.90, 4.67, and 11.90ppm against the larvae and LC50 and LC90 values of 4.58, 12.06, 5.36, and 13.07ppm against the pupae of Cx. quinquefasciatus and Ae. aegypti, respectively. On the other hand, the compound recorded less ovicidal activity of 11.0% and 10.3% at 2ppm against the eggs of Cx. quinquefasciatus and Ae. aegypti, respectively. The present study clearly shows that the crude extract and the compound from Nonomuraea sp. VAS-16 can be used as an effective biopesticide in integrated mosquito management program.

Development of cellulose nanocrystal-stabilized Pickering emulsions of massoia and nutmeg essential oils for the control of Aedes albopictus

We investigated the larvicidal potential of 10 plant essential oils (EOs) against the Asian tiger mosquito Aedes albopictus. Among the EOs, larvicidal activity against Ae. albopictus was strongest in those derived from massoia (Massoia aromatica) and nutmeg (Myristica fragrans). Larvicidal activities of massoia and nutmeg EOs against Ae. albopictus were 95.0% and 85.0% at 50 μg/mL, respectively. A total of 4 and 14 compounds were identified from massoia and nutmeg, respectively, and two massoia lactones, C10 and C12, were isolated from massoia EO. Among the identified compounds, benzyl salicylate, terpinolene, C12 massoia lactone, sabinene, benzyl benzoate, methyl eugenol, and C10 massoia lactone exhibited the strong larvicidal activity. Cellulose nanocrystal (CNC)-stabilized Pickering emulsions of massoia and nutmeg EOs were developed to overcome the insolubility of EOs in water. CNC/massoia and CNC/nutmeg emulsions were stable for at least 10 days, and larvicidal activities of CNC/massoia PE and CNC/nutmeg were higher than those of crude massoia and nutmeg EOs. This study presents a CNC-stabilized PE, a suitable formulation for EOs, as a potential larvicide against Ae. albopictus.

Volatiles from Marina neglecta: Biocide effect on insect vectors of tropical diseases in Southern Mexico

• Essential oils of M. neglecta contained β-pinene, β-caryophyllene and germacrene D. • Essential oils and main volatiles produced a biocide effect in four insect vectors. • β-Pinene produced significant and fast mortality in life stages of triatomines. • Germacrene D produced significant and fast mortality in life stages of mosquitoes. Preventive measures based in the control of insect vectors are considered as the best choice to decrease the incidence of insect-borne diseases. Herein we report on the volatile content of the leaf essential oils from Marina neglecta , a medicinal plant distributed in the tropical regions of southern Mexico. In order to investigate the chemical variation of the essential oils, a volatile screening was performed during the four seasons of the years 2016–2019. Simultaneously, their biological activity was tested on distinct life stages of Meccus pallidipennis , M. bassolsae , Aedes aegypti and A. albopictus . Essential oils were mainly constituted of β-pinene (>30%) β-caryophyllene (>25%) and germacrene D (>13%). Dorsal-abdomen application of essential oils on triatomines, revealed an efficient LC 50 for nymphs of the stages I to III (4 µg/insect), nymphs of the stages IV to V (5–6 µg/insect), and adults (7–8 µg/insect). The LT 50 for the stages I to III was between 6 and 8 h, whereas that for the stages IV to V and adults oscillated between 12 and 16 h and 22 to 26 h, respectively. Fumigation experiments performed on nymph V, demonstrated that 300 µg L −1 air produced 100% mortality after 72 h post-treatment. Among tested volatiles, β-pinene and β-caryophyllene produced a comparable mortality rate ( p < 0.01) than that of essential oils in the stages assayed. Essential oils showed strong larvicidal (LC 50 , 24–36 µg mL −1 ) and adulticidal (35–48 µg mL −1 ) activities in mosquito species with an LT 50 of 4.5 h and 25–35 min, respectively. The evaluation of β-pinene produced a significant mortality rate ( p < 0.01) in larvae whereas germacrene D was the most effective volatile ( p < 0.01) against adults of both mosquito species. According to our results, β-pinene was the most effective volatile against the four insect species evaluated and its effect was comparable to that of the essential oil.

Effect of Solanum lycopersicum leaf extracts against larvicidal activity of Aedes aegypti L.

Introduction: Aedes mosquitoes are responsible for transmitting various life-threatening diseases all over the world and created a burden to society. Control of mosquito vectors is the key challenge to avoid disease transmission. In this regard, the present work is focused to utilize the agronomical waste of Solanum lycopersicum leaf extracts and to evaluate the larvicidal activity against Aedes aegypti.&#x0D; Methods: The qualitative and quantitative screening of S. lycopersicum leaf extracts were carried out. The larvicidal activity of different concentrations were assessed against 3rd instar Ae. aegypti and to determine the morphological effects. The chemical constituents were analysed by gas chromatography coupled with mass spectroscopy (GC-MS).&#x0D; Results: The preliminary phytochemical screening of S. lycopersicum leaf extracts revealed the presence of alkaloids, saponins, phenols and flavonoids. The methanol extract exhibited strong larvicidal activity at 48h treatment with an LC50 value of 20.323mg/ml. The morphological changes revealed that abnormal movement and coiling of treated larvae at 24h. Furthermore, severe damage was noticed in the digestive and respiratory tract of Ae. aegypti larvae at 48h, later on complete mortality was observed. The GC-MS analysis of methanol extract showed chemical constituents such as phytol acetate (42.66%), neophytadiene (29.38%) and other minor compounds.&#x0D; Conclusion: Based on the results, it can be concluded that methanolic leaf extract of S. lycopersicum could be an alternative source to control mosquito vectors and further investigation is strongly suggested in order to utilise this source in many disease-endemic areas.

Larvicidal Activity of Elytraria acaulis against Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae).

Background:Mosquitoes are blood sucking arthropods and serve as vectors of many diseases causing serious health problems to human beings. Culex quinquefasciatus and Aedes aegypti were responsible for Filariasis and Dengue. Synthetic pesticides were effective against mosquitoes as well as main sources of environmental pollution and most of them are immunosuppressant. Botanicals were widely used as insecticides, growth disruptors, repellents, etc. The aim of this research was to determine larvicidal properties of powdered leaf, Elytraria acaulis against late third or early fourth in-star larvae of Cx. quinquefasciatus and Ae. aegypti.Methods:Larvae of Cx. quinquefasciatus and Ae. aegypti were tested at various concentrations of 100, 120, 140, 160, 180 and 200mg/100ml and mortality was recorded after 24h. The LC50 values of the E. acaulis leaf powder were calculated by Probit analysis.Results:The plant powder exhibited strong larvicidal activity against Cx. quinquefasciatus with LC50 value of 116.07mg/100ml against Ae. aegypti 124.25mg/100ml respectively. The result indicated that the plant powder of E. acaulis showed potential larvicidal activity against Cx. quinquefasciatus and Ae. aegypti.Conclusion:The overall findings of the present investigation suggested that the E. acaulis highly effective against Cx. quinquefasciatus and Ae. aegypti larvae. Elytraria acaulis may be used as an alternative to synthetic chemical pesticides for control of vectors to reduce vector borne diseases and did not harm to total environment.

Chemical profile, mosquitocidal, and biochemical effects of essential oil and major components of Dysphania ambrosioides against Culex quinquefasciatus Say

To seek new mosquito control agents while avoiding the environmental impacts and toxicity hazards of conventional pesticides, the essential oil of Dysphania ambrosioides was obtained by hydrodistillation and analysed using GC-FID and GC-MS. The compounds 1-methyl-4-(1-methylethyl)-2,3-dioxabicyclo[2.2.2]oct-5-ene (cis-ascaridole), 1-methyl-4-(1-methylethyl) benzene (р-cymene), and 1-isopropyl-4-methyl-1,3-cyclohexadiene (p-mentha-1,3-diene also known as α-terpinene) were identified as the major components. The EO and the major fractions showed remarkable mosquitocidal activity against third instar larvae and adults of Culex quinquefasciatus Say. The oil and fractions were assayed at 3.125, 6.25, 12.5, 25, and 50 μl/l. Mortality was time- and dose-dependent. At 24 h post-exposure at an assayed concentration of 50 μl/l, the larval and adult mortalities ranged between 80.11-100% and 91.22-100%, respectively. Strong larvicidal and adulticidal activities were recorded in the cases of the crude oil and cis-ascaridole. The LC50 values after 24 h of treatment ranged between 6.2-20.1 μl/l and 5.1-13.9 μl/l against larvae and adults, respectively. The corrected percentage mortalities increased over time with the tested plant oil and the major fractions relative to the control. The time required to achieve 50% mortality (LT50) decreased remarkably with all treatments. The tested EO and major fractions effectively inhibited larval acetylcholinesterase activity with IC50 values ranging from 8.44 to 64.80 mM compared with 2.08 × 10-3 mM for the reference standard, methomy. The results indicate the potential of developing natural mosquitocides against C. quinquefasciatus based on the tested EO and its major fractions. Graphical abstract.