Highest Larvicidal Activity Research Articles

Chemical composition and bio-efficacy of agro-waste plant extracts and their potential as bioinsecticides against Culex pipiens mosquitoes

Mosquitoes are considered one of the most lethal creatures on the planet and are responsible for millions of fatalities annually through the transmission of several diseases to humans. Green trash is commonly employed in agricultural fertilizer manufacturing and microbial bioprocesses for energy production. However, there is limited information available on the conversion of green waste into biocides. This study investigates the viability of utilizing green waste as a new biopesticide against Culex pipiens mosquito larvae. The current study found that plant extracts from Punica granatum (98.4 % mortality), Citrus sinensis (92 % mortality), Brassica oleracea (88 % mortality), Oryza sativa (81.6 % mortality), and Colocasia esculenta (53.6 % mortality) were very good at killing Cx. pipiens larvae 24 h post-treatment. The LC50 values were 314.43, 370.72, 465.59, 666.67, and 1798.03 ppm for P. granatum, C. sinensis, B. oleracea, O. sativa, and C. esculenta, respectively. All plant extracts, particularly P. granatum extract (14.93 and 41.87 U/g), showed a significant reduction in acid and alkaline phosphate activity. Additionally, pomegranate extract showed a significant decrease (90 %) in field larval density, with a stability of up to five days post-treatment. GC–MS results showed more chemical classes, such as terpenes, esters, fatty acids, alkanes, and phenolic compounds. HPLC analysis revealed that the analyzed extracts had a high concentration of phenolic and flavonoid components. Moreover, there are many variations among these plants in the amount of each compound. The docking interaction showed a simulation of the atomic-level interaction between a protein and a small molecule through the binding site of target proteins, explaining the most critical elements influencing the enzyme's activity or inhibitions. The study's findings showed that the various phytochemicals found in agro-waste plants had high larvicidal activity and provide a safe and efficient substitute to conventional pesticides for pest management, as well as a potential future in biotechnology.

Larvicidal potency of four Egyptian herbs on Culex pipiens larvae: Phytochemical composition and molecular networking for most potent extracts

Utilizing synthetic insecticides to control mosquito populations has many adverse side effects as they can cause environmental pollution and insecticide resistance. Therefore, the search for eco-friendly and effective mosquito control agents has led to the exploration of plant extracts with larvicidal efficacy. In this study, we aimed to explore the larvicidal activity of four Egyptian plant extracts: Rosmarinus officinalis, Melissa officinalis, Cichorium intybus, and Beta vulgaris var. cicla against Culex pipiens and to identify the chemical constituents present in the active extracts. The methanolic extracts of the four plants were prepared and tested against the third instar larvae of C. pipiens using a standard method. The lethal concentrations (LC50 and LC90) were calculated using probit analysis. The active extracts were subjected to ultra-performance liquid chromatography-mass spectroscopy (UPLC-MS/MS) analysis and the data were processed using the global natural products social molecular networking (GNPS) platform to generate molecular networks and identify the compounds based on spectral similarity and database matching. The methanolic extracts of R. officinalis L. and M. officinalis L. had the highest larvicidal activity, where LC50 values were 9.795 and 26.505 μg/mL, respectively. Their exposure caused a high mortality rate and disrupted the biochemical and physiological parameters (total carbohydrates, total lipids, total protein, acetylcholinesterase (AChE), and glutathione S-transferase (GST) in the body of C. pipiens when compared with Cichorium intybus (Chicory) and Beta vulgaris var. cicla (Chard). The UPLC-MS/MS analysis with the aid of the GNPS platform, revealed the presence of 23 and 41 metabolites from R. officinalis L. and M. officinalis L., respectively. The identified metabolites may act as larvicidal agents by interfering with the physiological or biochemical processes of the mosquito larvae. Overall, the findings suggest that the methanolic extracts of R. officinalis and M. officinalis are potential sources of natural larvicides for mosquito control.

Larvicidal activity of liverworts’ (Marchantia paleacea) ethyl acetate fraction against Athalia proxima

Abstract Indonesia is an agrarian country with extensive agricultural land and a variety of crop types. One of the challenges faced by farmers when cultivating crops is pest infestation. The larval stage of Athalia proxima attacks cruciferous plants, leading to a 65-80% decrease in productivity. Continuous use of synthetic larvicides has negative impacts such as pest resistance, harm to natural plant enemies, and environmental pollution. This research aims to investigate the larvicidal activity of the ethyl acetate fraction of ethanol extract from liverworts (Marchantia paleacea) against A. proxima. The stages of compound isolation included extraction and fractionation. Compound groups in the fraction were identified through phytochemical screening. The larvicidal activity testing method used was the spray method. The concentrations of liverwort ethyl acetate fraction used were 0.4%, 0.6%, 0.8%, and 1%. Distilled water was used as a negative control. Larval mortality was observed 24 hours after application and analyzed using probit analysis to determine the LC50 value. Phytochemical screening results indicated that the ethyl acetate fraction tested positive for alkaloids, phenolics, flavonoids, terpenoids, and steroids. The LC50 value of the ethyl acetate fraction of the ethanol extract from M. paleacea was 0.33%. Therefore, the ethyl acetate fraction of M. paleacea exhibited high larvicidal activity against A. proxima.

Marching towards bioeconomy: Larvicidal effect of three indigenous plant extracts from Sri Lanka—Garcinia quaesita, Garcinia zeylanica, and Coleus hadiensis on dengue vector Aedes aegypti

AbstractBioeconomy would be a beneficial solution for funding through the rational use of finances and human resources in order to achieve better productivity and fruitfulness of mosquito control programs. Synthetic insecticides are widely used to repress mosquitoes. However, it instigates problems such as insecticide resistance among mosquitoes such as developing resistance, bio‐accumulation, and ecosystem destabilization. Natural plant‐based products are a healthy alternative to use as mosquito larvicides. The country has to spend a considerable cost for buying synthetic insecticides too. Therefore, the present study was undertaken to evaluate larvicidal efficacy of Garcinia zeylanica, Garcinia quaesita, and Coleus hadiensis against Aedes aegypti mosquito larvae. Fresh leaves of plants were collected, and the aqueous crude extract was prepared. Phytochemicals were extracted using refluxing technique. A concentration series of crude extract of leaves were prepared separately from 20 to 100 mg/L. Batches of each containing 100 third instar larvae of Ae. aegypti were used for larval bioassays. Ae. aegypti mosquito larvae were evaluated in accordance with the guidelines of World Health Organization. The experimental setup was repeated four times at each concentration. Probit analysis was used to evaluate the relationship of mortality with the concentration of aqueous crude extract. The G. zeylanica and G. quaesita leaf extracts showed a dose‐dependent effect against Ae. aegypti larvae after the 24 and 48 h exposure period. Interestingly, C. hadiensis did not show any dose‐dependent effect against A. aegypti mosquito larvae. The percentage mortality rates have shown a significant variance among different concentrations (P = 0.000). The recorded LC50 and LC90 for aqueous crude extract of G. zeylanica were 27.167 and 52.861 g/L, respectively, and LC50 and LC90 for aqueous crude extract of G. quaesita were 36.841 and 76.036 g/L, respectively, after 24 h of exposure period. The G. zeylanica and G. quaesita plant's high larvicidal activity is supported by the presence of phytochemicals such as saponins, steroids, flavonoids, and phenol, which showed combination effects in terms of larvicidal action to mosquito larvae. Hence, there is a potential of G. zeylanica and G. quaesita aqueous leaf extracts as a key source for the development of an environment‐friendly plant‐based larvicide against Ae. aegypti. Hence, this warrants vector control entities to re‐think “biological wealth for economic prosperity” with environmentally friendly country‐wide control approaches for medically important disease vectors.

Assessment of the chemical profile and potential biocontrol of Amphora coffeaeformis against foodborne pathogens and Culex pipiens L. to ensure food safety

AbstractThe extensive use of synthetic antibiotics and insecticides in controlling microbes and insect spreads led to a build‐up of resistance strains and caused negative impacts on human health through bioaccumulation in food and the environment. The present study assessed the antimicrobial activity of Amphora coffeaeformis (A. coffeaeformis) ethanolic extract against foodborne pathogenic microbes as well as assessed its ability to control Culex pipiens L. (C. pipiens) larvae. The gas chromatography–mass spectrum (GC/MS) and high‐performance liquid chromatography (HPLC) analysis showed that A. coffeaeformis extract was rich with phenolic compounds, organosulfur compounds, carboxylic acids, amino acids, organic quinoline, dipeptide and monosaccharide. The extract of A. coffeaeformis showed antibacterial capability against all tested bacteria, with minimal inhibition concentration (MIC) values ranging from 20.2 to 66.7 g/mL, as well as antifungal effects against all tested mycotoxigenic fungi, with MIC values ranging from 113.62, 68.95 and 49.37 μg/mL mg/mL. Furthermore, the extract showed high larvicidal activity against C. pipiens larvae at 24, 48, and 72 h, respectively. LC50 values decreased gradually with the treatment period. Likewise, the adult emergence and growth index were significantly negatively related to increasing extract concentrations. Moreover, the extract exhibited a noteworthy depletion in the reproductive potential and increased sterility index of C. pipiens females developed of treated larvae. Besides a reduction in egg hatching percent, increase pupal malformations, increase and adult abnormalities. C. pipiens biochemical markers; glutathione‐S‐transferase, carboxylesterase, acetylcholinesterase, α‐esterase and cytochrome P‐450 showed significant alteration after the extract exposure. Overall, these findings promise the application possibility of A. coffeaeformis extract as a biopreservator against foodborne pathogens and as bioinsecticides for mosquito control as well.

1,2-Diboranes with strong donor substitutes: Synthesis, ovicidal and larvicidal effect on important vector species

Novel control products are needed in the control of important insects like mosquitoes which are developing resistance to insecticides and larvicides currently in the market. Boron compounds have been demonstrated to exhibit antibacterial and anticancer effects. 1,2-diboranes with a long history and importance in boron chemistry have been described. These compounds are synthesized from reactions of 1,2-dichlordiborane derivatives with lidium amides (ArNHLi/Et2NLi, etc.). In addition to the three previously synthesized diborane compounds, five novel 1,2-diborane compounds were synthesized in good yield using the same method for the first time. The structures of the novel derivatives were characterized by nuclear magnetic resonance spectroscopy, and the molecular structure of one of them (2a) was also demonstrated using single crystal X-ray diffraction. In this preliminary study, the ovicidal and larvicidal effects of new 1,2-diamino-1,2-diborane derivatives against Aedes aegypti and Aedes albopictus eggs and larvae were investigated for the first time. Of these, 2a and 2e showed the highest ovicidal activity against both species, while 7, 4 and 2d showed particularly high larvicidal activity. Some 1,2-diborane derivatives were found to be significantly toxic, with LC50 values ranging from 14,930 to 27,975 μg/mL. Some derivatives (6, 2a, 2c) were less effective against mosquito larvae. 1,2-Diborane derivatives have high ovicidal and larvicidal effects on mosquitoes and are therefore potential candidates for the development of new larvicides. Further studies are needed to evaluate its mode of action and safety. Understanding their mode of action against mosquito development is crucial to optimizing their use and reducing the potential development of resistance. Their potential effects on other mosquito species and non-target organisms need to be investigated.

Insecticidal activity and underlying molecular mechanisms of a phytochemical plumbagin against Spodoptera frugiperda.

Plumbagin is an important phytochemical and has been reported to exhibit potent larvicidal activity against several insect pests, However, the insecticidal mechanism of plumbagin against pests is still poorly understood. This study aimed to investigate the insecticidal activities of plumbagin and the underlying molecular mechanisms against a devastating agricultural pest, the fall armyworm Spodoptera frugiperda. The effects of plumbagin on S. frugiperda larval development and the activities of two detoxification enzymes were initially examined. Next, transcriptomic changes in S. frugiperda after plumbagin treatment were investigated. Furthermore, RNA-seq results were validated by qPCR. Plumbagin exhibited a high larvicidal activity against the second and third instar larvae of S. frugiperda with 72h LC50 of 0.573 and 2.676mg/g, respectively. The activities of the two detoxification enzymes carboxylesterase and P450 were significantly increased after 1.5mg/g plumbagin treatment. Furthermore, RNA-seq analysis provided a comprehensive overview of complex transcriptomic changes in S. frugiperda larvae in response to 1.5mg/g plumbagin exposure, and revealed that plumbagin treatment led to aberrant expression of a large number of genes related to nutrient and energy metabolism, humoral immune response, insect cuticle protein, chitin-binding proteins, chitin synthesis and degradation, insect hormone, and xenobiotic detoxification. The qPCR results further validated the reproducibility and reliability of the transcriptomic data. Our findings provide a valuable insight into understanding the insecticidal mechanism of the phytochemical plumbagin.

Investigation On the Larvicidal Potential of Endophytic Fungi Isolates from Psoralea corylifolia And Leptadenia reticulata Against Aedes Aegypti

Globally, several million peoples are infected with epidemic-prone mosquito-borne diseases like yellow fever and malaria that is transmitted to humans by the bites of infected mosquitoes. Psoralea corylifolia, often known as babchi, is a well-liked herb that has been utilised in traditional Ayurvedic and Chinese medicine for many years for its miraculous abilities to treat a variety of skin conditions and Leptadenia reticulata, also known as Jivanti is an herb that is traditionally used in treating the conditions like malaria, diabetes, and liver disorders. The present study investigated the larvicidal properties of endophytic fungi isolated from Psoralea corylifolia and Leptadenia reticulata against Aedes aegypti. The highest larvicidal activity was seen in Trichodermata viride and Candida albicans species from leaves of L. reticulata was found to be 85.71% and 90.47 at 20 ppm. Likewise, Piriformospora indica and Aspergillus niger species from the leaves of P. corylifolia was found to be 66.66% and 83.33 % respectively. Candida albicans from leaves of L. reticulata and Aspergillus niger from the leaves of Psoralea corylifolia showed the highest mortality percentage was found to be 90.47 and 83.33 at 20 ppm respectively. The present study reveals the determination of optimal, eco-friendly, and selective mosquito larvicidal agents. The development of innovative and affordable medications to combat diseases spread by mosquitoes will be aided by more research on the isolation, characterisation, and determination of the mechanism of action against the selective mosquitos.

Exploring the Sustainable Exploitation of Bioactive Compounds in Pelargonium sp.: Beyond a Fragrant Plant.

This review article aims to present an overview regarding the volatile compounds in different scented species of Pelargonium and their biological activities, immunomodulatory activity, cytotoxic activity, high larvicidal activity and ethnopharmacological uses. Although the Pelargonium genus includes many species, we focused only on the scented ones, with the potential to be used in different domains. Pelargonium essential oil showed great properties as antioxidant activity, antibacterial activity (against K. pneumonie, S. aureus or E. coli strains) and antifungal activity (against many fungi including Candida sp.), the responsible compounds for these properties being tannins, flavones, flavonols, flavonoids, phenolic acids and coumarins. Due to the existence of bioactive constituents in the chemical composition of fresh leaves, roots, or flowers of Pelargonium sp. (such as monoterpenoid compounds-citronellol, geraniol, linalool, and flavonoids-myricetin, quercetin and kaempferol), this species is still valuable, the bio-compounds representing the base of innovative substitutes in food processing industry, nutraceuticals, or preventive human or veterinary medicine (substitute of antibiotics). Highlighting the volatile chemical composition and properties of this scented plant aims to rediscover it and to emphasize the vast spectrum of health-promoting constituents for a sustainable approach. Future research directions should point to the application of plant biotechnology with a significant role in conservation strategy and to stimulate commercial interest.

Effects of Arabika Coffee (Coffea arabica L.) Pulp Extracts on Anopheles sp. Larva Mortality

Malaria is one of the main public health problems in Indonesia. Anopheles sp. mosquito larvae is vector of malaria that must be treated before it develops into a mosquito. Control of larvae by using larvicides containing hazardous chemicals causes side effects on the environment and resistance. This study aimed to determine the effect of giving the Arabika Coffee (Coffea arabica L.) pulp extracts on the mortality of Anopheles sp. larvae. Arabika coffee pulp extracts was fractionated with polar, semi-polar and non-polar. This study used ten larvae of Anopheles sp. Observations of larval mortality were carried 24 hours with five concentration series (0, 125, 250, 500, and 1000 ppm). The results of the mortality test showed that non-polar fraction of Arabika coffee pulp extracts had the highest larvicidal activity with values of LC50 and LC90, 278 ppm and 22950 ppm. In semi-polar and polar fractions, the LC50 and LC90, 1718 and 92683 ppm, 34085 and 40862 ppm were obtained. The results of compound analysis obtained 16 active compounds from non-polar extract of arabika coffee pulp with the five highest compounds, namely Hexadecanoic acid, 9,12-Octadecadienoic 15-Octadecenoic acid, Octadecanoic acid and 3-Furanacetic acid. Non-polar fraction of arabika coffee pulp extracts had larvicidal activity against Anopheles sp.

Green synthesis, characterization, and biochemical impacts of new bioactive isoxazoline-sulfonamides as potential insecticidal agents against the Sphodroxia maroccana Ley.

Sphodroxia maroccana Ley is a pest of cork oak crops that damages the roots of seedlings and can severely impair cork oak regeneration. Since the banning of carbosulfan and chlorpyriphos, which were widely used against the larvae of Sphodroxia maroccana because of their harmful impact on the environment, until now there has been no pesticide against these pests. Therefore, it is particularly urgent to develop highly effective insecticidal molecules with novel scaffolds. Isoxazolines are a class of insecticides that act on γ-aminobutyric acid (GABA)-gated chloride channel allosteric modulators. In this work, a green synthesis of novel 3,5-disubstituted isoxazoline-sulfonamide derivatives was achieved in water via ultrasound-assisted four-component reactions, and their insecticidal activities against fourth-instar larvae of S. maroccana were evaluated. Most of the tested compounds showed insecticidal activity compared to fluralaner as positive control and commercially available insecticide. Especially, the isoxazoline-secondary sulfonamides containing halogens (Br and Cl) on the phenyl group attached to the isoxazoline, 6g (LC50 = 0.31 mg/mL), 6j (LC50 = 0.38 mg/mL), 6k (LC50 = 0.18 mg/mL), 6L (LC50 = 0.49 mg/mL), 6m (LC50 = 0.24 mg/mL), 6q (LC50 = 0.46 mg/mL), exhibited much higher larvicidal activity than fluralaner (LC50 = 0.99 mg/mL). Novel isoxazolines containing sulfonamide moieties were designed, synthesized and confirmed by two single-crystal structures of 4e and 6q. Their bioassay results showed significant larvicidal activity with significant morphological changes in vivo. These results will lay the foundation for the further discovery and development of isoxazoline-sulfonamide derivatives as novel crop protection larvicides of cork oak. © 2023 Society of Chemical Industry.

Larvicidal activities of Cnidium officinale Makino extract encapsulated with cellulose nanocrystal-stabilized Pickering emulsion against Aedes albopictus Skuse, a vector of Zika virus

Phytochemicals extracted from plant structures are an appropriate alternative pesticide to prevent side effects from synthetic pesticides, such as environmental problems, direct damage to other organisms, and strong mutations. Since some phytochemicals with larvicidal activities against mosquito larvae have low surface tension, phytochemicals must be encapsulated with hydrophilic structures to be applied in the aqueous phase. Here, we suggest a phytochemical encapsulation method with sulfated cellulose nanocrystal (S-CNC) via Pickering emulsification. Before Pickering emulsification, 11 herbal plant extracts were studied for their larvicidal activities against Aedes albopictus Skuse to investigate a novel plant extract found in traditional medicine in Northeast Asian countries. Among them, Cnidium officinale Makino and Syzygium aromaticum (L.) Merr. & L. M. Perry exhibited outstanding larvicidal activity, and C. officinale showed approximately 1.9-fold higher larvicidal activity than S. aromaticum at the same concentration. After analysis of C. officinale root methanol extract (CoRM), we emulsified CoRM with various concentrations of S-CNC to improve the low solubility of CoRM to the aqueous phase. The colloidal stability of S-CNC-stabilized CoRM Pickering emulsion was examined in terms of phase behavior, droplet size distribution, rheological properties, surface tension, and zeta potential during storage. Then, we investigated the larvicidal activity of the Pickering emulsion, and Pickering emulsified CoRM showed 100% mortality at 0.125 mg mL−1 concentration against Ae. albopictus larvae. These results demonstrated that the Pickering emulsification with S-CNC can be utilized to encapsulate the larvicidal plant extracts, leading to improved management of insect-borne diseases.

Sonication and heat-mediated synthesis, characterization and larvicidal activity of sericin-based silver nanoparticles against dengue vector (Aedes aegypti).

Fabrication, characterization and evaluation of the larvicidal potential of novel silk protein (sericin)-based silver nanoparticles (Se-AgNPs) were the prime motives of the designed study. Furthermore, investigation of the sericin as natural reducing or stabilizing agent was another objective behind this study. Se-AgNPs were synthesized using sonication and heat. Fabricated Se-AgNPs were characterized using particle size analyzer, UV spectrophotometry, FTIR and SEM which confirmed the fabrication of the Se-AgNPs. Size of sonication-mediated Se-AgNPs was smaller (7.49 nm) than heat-assisted Se-AgNPs (53.6 nm). Being smallest in size, sonication-assisted Se-AgNPs revealed the significantly highest (F4,10 = 39.20, p = .00) larvicidal activity against fourth instar lab and field larvae (F4,10 = 1864, p = .00) of dengue vector (Aedes aegypti) followed by heat-assisted Se-AgNPs and positive control (temephos). Non-significant larvicidal activity was showed by silver (without sericin) which made the temperature stability of silver, debatable. Furthermore, findings of biochemical assays (glutathione-S transferase, esterase, and acetylcholinesterase) showed the levels of resistance in field strain larvae. Aforementioned findings of the study suggests the sonication as the best method for synthesis of Se-AgNPs while the larvicidal activity is inversely proportional to the size of Se-AgNPs, i.e., smallest the size, highest the larvicidal activity. Conclusively, status of the sericin as a natural reducing/stabilizing agent has been endorsed by the findings of this study. RESEARCH HIGHLIGHTS: Incorporation of biocompatible and inexpensive sericin as a capping/reducing agent for synthesis of Se-AgNPs. A novel sonication method was used for the fabrication of Se-AgNPs which were thoroughly characterized by particle size analyzer, UV-visible spectrophotometry, SEM and FTIR. Analysis of enzymatic (GSTs, ESTs) levels in field and lab strains of Aedes aegypti larvae for evaluation of insecticides resistance.

The Mosquito Larvicidal Activity of Lignans from Branches of Cinnamomum camphora chvar. Borneol.

The chemical investigation of branches of Cinnamomum camphora chvar. Borneol guided by mosquito larvicidal activity led to the isolation of fourteen known lignans (1-14). Their structures were elucidated unambiguously based on comprehensive spectroscopic analysis and comparison with the literature data. This is the first report of these compounds being isolated from branches of Cinnamomum camphora chvar. Borneol. Compounds 3-5 and 8-14 were isolated from this plant for the first time. All compounds isolated were subjected to anti-inflammatory, mosquito larvicidal activity and cytotoxic activity evaluation. Compounds (1-14) showed significant mosquito larvicidal activity against Culex pipiens quinquefasciatus with lethal mortality in 50% (LC50), with values ranging from 0.009 to 0.24 μg/mL. Among them, furofuran lignans(1-8) exhibited potent mosquito larvicidal activity against Cx. p. quinquefasciatus, with LC50 values of 0.009-0.021 μg/mL. From the perspective of a structure-activity relationship, compounds with a dioxolane group showed high mosquito larvicidal activity and have potential to be developed into a mosquitocide.

Bio-efficacy of insecticidal molecule emodin against dengue, filariasis, and malaria vectors.

Emodin, a compound isolated from Aspergillusterreus, was studied using chromatographic and spectroscopic methods and compound purity (96%) was assessed by TLC. Furthermore, high larvicidal activity against Aedes aegypti-AeA (LC50 6.156 and LC90 12.450mg/L), Culex quinquefasciatus-CuQ (8.216 and 14.816mg/L), and Anopheles stephensi-AnS larvae (6.895 and 15.24mg/L) was recorded. The first isolated fraction (emodin) showed higher pupicidal activity against AeA (15.449 and 20.752mg/L). Most emodin-treated larvae (ETL) showed variations in acetylcholine esterase, α and β-carboxylesterases, and phosphatase activities in the 4th instar, indicating the intrinsic differences in their biochemical changes. ETL had numerous altered tissues, including muscle, gastric caeca, hindgut, midgut, nerve ganglia, and midgut epithelium. Acute toxicity of emodin on brine shrimp Artemia nauplii (54.0 and 84.5mg/L) and the zebrafish Danio rerio (less toxicity observed) was recorded. In docking studies, Emodin interacted well with odorant-binding-proteins of AeA, AnS, and CuQ with docking scores of - 8.89, - 6.53, and - 8.09kcalmol-1, respectively. Therefore, A. terreus is likely to be effective against mosquito larvicides.

Phytofabrication and characterization of Alchornea cordifolia silver nanoparticles and evaluation of antiplasmodial, hemocompatibility and larvicidal potential.

Purpose: The recent emergence of Plasmodium falciparum (Pf) parasites resistant to current artemisinin-based combination therapies in Africa justifies the need to develop new strategies for successful malaria control. We synthesized, characterized and evaluated medical applications of optimized silver nanoparticles using Alchornea cordifolia (AC-AgNPs), a plant largely used in African and Asian traditional medicine. Methods: Fresh leaves of A. cordifolia were used to prepare aqueous crude extract, which was mixed with silver nitrate for AC-AgNPs synthesis and optimization. The optimized AC-AgNPs were characterized using several techniques including ultraviolet-visible spectrophotometry (UV-Vis), scanning/transmission electron microscopy (SEM/TEM), powder X-ray diffraction (PXRD), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), Fourier transformed infrared spectroscopy (FTIR), dynamic light scattering (DLS) and Zeta potential. Thereafter, AC-AgNPs were evaluated for their hemocompatibility and antiplasmodial activity against Pf malaria strains 3D7 and RKL9. Finally, lethal activity of AC-AgNPs was assessed against mosquito larvae of Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti which are vectors of neglected diseases such as dengue, filariasis and chikungunya. Results: The AC-AgNPs were mostly spheroidal, polycrystalline (84.13%), stable and polydispersed with size of 11.77 ± 5.57nm. FTIR revealed the presence of several peaks corresponding to functional chemical groups characteristics of alkanoids, terpenoids, flavonoids, phenols, steroids, anthraquonones and saponins. The AC-AgNPs had a high antiplasmodial activity, with IC50 of 8.05μg/mL and 10.31μg/mL against 3D7 and RKL9 Plasmodium falciparum strains. Likewise, high larvicidal activity of AC-AgNPs was found after 24h- and 48h-exposure: LC50 = 18.41μg/mL and 8.97μg/mL (Culex quinquefasciatus), LC50 = 16.71μg/mL and 7.52μg/mL (Aedes aegypti) and LC50 = 10.67μg/mL and 5.85μg/mL (Anopheles stephensi). The AC-AgNPs were highly hemocompatible (HC50 > 500μg/mL). Conclusion: In worrying context of resistance of parasite and mosquitoes, green nanotechnologies using plants could be a cutting-edge alternative for drug/insecticide discovery and development.

The transcriptomic profile of Spodoptera frugiperda differs in response to a novel insecticide, cyproflanilide, compared to chlorantraniliprole and avermectin

BackgroundCyproflanilide is a novel chemical that is already undergoing insecticide registration in China and has been categorized as a member of group 30 by the IRAC. Since it was first detected in 2019, the fall armyworm (FAW), Spodoptera frugiperda, has become a serious pest in China. Our laboratory and field efficacy trials indicated that cyproflanilide exhibits high larvicidal activity against FAW. However, the effect of cyproflanilide against FAW remains unknown. And it is worth exploring further before the cyproflanilide becomes commercially available.ResultsWe found larvae exposed to cyproflanilide had significantly shorter body length and higher death rates compared to control larvae. Additionally, we found surviving larvae had a significantly longer developmental period compared to control larvae. The potential molecular mechanisms of cyproflanilide against FAW were investigated using comparative transcriptomic analyses on larval samples subjected to three insecticide treatments, including cyproflanilide and two other commonly used insecticides against FAW in China, chlorantraniliprole and avermectin. We found that several subunits of the γ-aminobutyric acid receptor (GABAR), a possible target protein of cyproflanilide, were significantly up-regulated at the transcriptional level during cyproflanilide-induced stress. Additionally, between the control and cyproflanilide-treated samples, we identified 131 differentially expressed genes (DEGs) associated with detoxification metabolism. Of these, we found four P450 genes that were significantly up-regulated under cyproflanilide stress but were not DEGs when exposed to chlorantraniliprole and avermectin, or 23 other pesticides from previous reports. Furthermore, we discovered an interesting gene aggregation region for insect cuticle proteins (CPs) on the 18th chromosome, which is likely related to FAW cross-resistance to cyproflanilide and avermectin.ConclusionsOur results contribute to a greater understanding of the mechanisms by which cyproflanilide affects FAW. Additionally, we identified the similarities and differences in transcriptomic profiling of FAW between the novel insecticide cyproflanilide and two other commonly used insecticides.

Activity of essential oils from leaves, flower buds and stems of Tetradenia riparia on Rhipicephalus (Boophilus) microplus larvae.

Around the world, the main problems of livestock are caused by ectoparasites, however, commercial acaracide are toxic to the environment and detrimental to One Health. Therefore, research has increasingly focused on development of natural products as alternatives for tick control. The purpose of this study was to evaluate the larvicidal effect on Rhipicephalus (Boophilus) microplus, through use of essential oils (EOs) extracted from the leaves, flower buds and stems of Tetradenia riparia. The chemical composition of these EOs was determined through gas chromatography coupled to mass spectrometry (GC-MS). They were tested on larvae at concentrations of 100.000 to 40 µg/mL, using the larval packet test and under semi-natural conditions. The main class of compounds in the chemical composition was sesquiterpenes (both oxygenates and hydrocarbons), whereas the predominant compounds in the leaves, flower buds and stems were 14-hydroxy-9-epi-caryophyllene, T-cadinol and 6-7-dehydroroyleanone, respectively. The leaves proved to be the most effective, with highest larvicidal activity (LC99.9 = 83.53 µg/mL). When tested under semi-natural conditions, the oils obtained efficiency above 98% in all compound tests. The results indicated that these EOs were effective against R. (B.) microplus larvae in vitro and ex-situ, proving that this plant has bioactive molecules with significant larvicidal activity.

Use of essential oils from plants of Araripe National Forest against Aedes aegypti (Diptera: Culicidae).

Aedes aegypti control is achieved with chemical insecticides that can promote insecticide resistance. In the search for new forms of control, the use of botanical products is currently growing and many tests with oils have already been performed. The plant diversity of Araripe National Forest enables the study of several species against this vector. To evaluate the larvicidal effect of essential oils from plants of this forest, we used field rosemary, copaiba, bay leaf, cashew and pequi. The work was divided into three stages: all oils with the same dosage; the best oil at dosages of 0, 5, 10, 20, 50 and 75 µg/mL; and the best dosage at temperatures of 15, 20, 25, 30 and 35 °C. The oils of field rosemary, copaiba, bay leaf, cashew and pequi were good insecticides when used at dosages above 5 μg/mL. The bay leaf oil showed high larvicidal activity at all dosages tested, showing the highest efficiency at 75 μg/mL. Temperatures of 15 and 35 °C increased the susceptibility of the insect to the effect of the bay leaf oil. The essential oils of field rosemary, copaiba, bay leaf, cashew and pequi, from Araripe National Forest, applied at a dosage of 5μg/mL, showed insecticidal action, although with low efficiency.

Chemical composition, in vitro larvicidal and antileishmanial activities of the essential oil from Citrus reticulata Blanco fruit peel.

Numerous studies have investigated the chemical composition and biological activities of essential oils from different Citrus species fruit peel, leaves and flowers. This paper aims to investigate the chemical composition, larvicidal and antileishmanial activities of essential oil from Citrus reticulata fruit peel (CR-EO). CR-EO was obtained by hydrodistillation in a Clevenger-type apparatus and its chemical composition was analyzed by GC-MS and GC-FID. Limonene (85.7%), ɣ-terpinene (6.7%) and myrcene (2.1%) were identified as its major components. CR-EO showed high activity against promastigote forms of Leishmania amazonensis (IC50 = 8.23 µg/mL). CR-EO also exhibited high larvicidal activity against third instar Aedes aegypti larvae at a lethal concentration (LC50 = 58.35 µg/mL) and 100% mortality at 150 µg/mL. This study suggests, for the first time, the potential use of CR-EO against this important mosquito-borne viral disease caused by the genus Aedes.