Culex Quinquefasciatus Larvae Research Articles

Comparative genomic analysis and mosquito larvicidal activity of four Bacillus thuringiensis serovar israelensis strains

Bacillus thuringiensis serovar israelensis (Bti) is used to control insect vectors of human and animal diseases. In the present study, the toxicity of four strains of Bti, named T0124, T0131, T0137, and T0139, toward Aedes aegypti and Culex quinquefasciatus larvae was analyzed. The T0131 strain showed the highest larvicidal activity against A. aegypti (LC50 = 0.015 µg/ml) and C. quinquefasciatus larvae (LC50 = 0.035 µg/ml) when compared to the other strains. Furthermore, the genomic sequences of the four strains were obtained and compared. These Bti strains had chromosomes sizes of approximately 5.4 Mb with GC contents of ~35% and 5472–5477 putative coding regions. Three small plasmids (5.4, 6.8, and 7.6 kb) and three large plasmids (127, 235, and 359 kb) were found in the extrachromosomal content of all four strains. The SNP-based phylogeny revealed close relationship among isolates from this study and other Bti isolates, and SNPs analysis of the plasmids 127 kb did not reveal any mutations in δ-endotoxins genes. This newly acquired sequence data for these Bti strains may be useful in the search for novel insecticidal toxins to improve existing ones or develop new strategies for the biological control of important insect vectors of human and animal diseases.

Isolation and identification of entomopathogenic fungus from Eastern Ghats of South Indian forest soil and their efficacy as biopesticide for mosquito control.

The repeated usage of chemical insecticides, responsible for insecticide resistance in mosquitoes and environmental toxicity. Currently effective and environmental-safe control strategies are needed for the control disease-vector mosquitoes. Entomopathogens can be an effective alternative to chemical insecticide. Herein we isolated and tested 46 soil-borne entomopathogenic fungi belonging to six genera, namely Beauveria sp., Metarhizium sp., Fusarium sp., Aspergillus sp., Trichoderma sp., and Verticillium sp., fungi conidia were tested on Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus larvae. Bioassays results show that M. anisopliae fungal isolate causes a 100%, 98.6% and 92% mortality within six days, on Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus, respectively. M. anisopliae treated three mosquito larvae have lower lifetime with LT50 values in A. stephensi, 2.931days; A. aegypti, 2.676days and C. quinquefasciatus, 3.254days. 18s rDNA sequence analysis confirmed that the isolated fungus are belonging to the genus of M. anisopliae-VKKH3, B. bassiana-VKBb03, and V. lecanii-VKPH1. Our results clearly show that M. anisopliae has good potential, as a low-cost, environmentally safe tool for the control of A. aegypti, A. stephensi, and C. quinquefasciatus mosquitoes.

Effectiveness of Aquatain® AMF and Cocobear™ Larvicidal Oil Against Culex quinquefasciatus Larvae and Pupae in an Organically Enhanced Aquatic Habitat.

The efficacy of CocoBear™ Larvicidal Oil and Aquatain® AMF Liquid Mosquito Film against larval and pupal Culex quinquefasciatus was compared (at maximum label field application rates) when applied to concrete troughs treated with composted cow manure. At 1 h posttreatment, CocoBear provided significantly greater reduction of mosquito larvae than Aquatain, but both products were equally effective in producing >97% control at 24 h. Each product provided >98% pupal reduction at 1 h posttreatment, with complete elimination of pupae from troughs at 24 h. CocoBear and Aquatain proved to be equally effective against Cx. quinquefasciatus immatures in organically enriched aquatic habitats.

Larvicidal Activity of Neolamarckia cadamba Against the Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus

The excessive use of conventional insecticides to Culicidae leads to the emergence of mosquitoe resistant, adverse environmental and human effects. Therefore, the present study was carried out to explore the larvicidal efficacy of petroleum ether, chloroform, ethyl acetate and methanol extracts of roots, leaves, and bark of Neolamarckia cadamba against the early 4th instar larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus at concentrations ranging from 12.5 to 200 ppm under laboratory conditions. The root extracts showed the highest larvicidal potential than the leaf and bark extracts. After 24 h of exposure period, the highest larvicidal activities were observed in the methanol extract of roots with LC50 value of 43.29 and LC90 value of 202.85 ppm against An. stephensi; LC50 value of 70.82 and LC90 value of 253.73 ppm against Ae. Aegypti and LC50 value of 99.51 and LC90 value of 311.02 ppm against the Cx. Quinquefasciatus, respectively. Thus, the plant extracts of N. cadamba showed considerable mosquito larvicidal activities and can be considered for further investigation.

First record of the mosquito control potentiality of Stigmatogobius sadanundio (F. Hamilton, 1822) Gobiidae, Perciformes in laboratory condition.

Background and Objectives:In recent years, resurgence of mosquito-borne diseases has become a serious health problem in India. In the present study, Stigmatogobius sadanundio, a common indigenous fish, has been tested for its biocontrol potentiality for controlling Culex quinquefasciatus larvae. This small larvivorous fish can consume large number of Culex larvae even in the presence of alternate prey. This is the first report on the mosquito control ability of this fish.Materials and Methods:Experimental fishes were captured from tidal canals of Rupnarayan River in Purba Medinipur district, West Bengal. Mosquito larvae, pupae, and chironomid larvae were collected from Tamralipta municipality drainage system. Predation efficacy of the fish was evaluated on C. quinquefasciatus larvae and pupae as well as on Chironomus ramosus larvae which were collected from the drainage system of Tamralipta municipality and reared in the laboratory maintaining similar water parameters. Prey were offered to the fish separately and in paired combination to study its dietary preference.Results:S. sadanundio is a diurnal predator consuming significantly large number of prey during daytime. It prefers mosquito and chironomid larvae over mosquito pupae. The rate of predation was very high during 1st h of predation. It consumed more chironomid larvae in the presence of mosquito larvae during daytime but consumed large number of mosquito larvae as compared to other larvivorous fish.Conclusion:S. sadanundio, an indigenous fish, is an effective biocontrol agent for the larvae of C. quinquefasciatus in laboratory condition. Even though the presence of alternate prey chironomid larvae influences the predation rate, it consumed large number of mosquito larvae. However, careful controlled field trials must be conducted before this fish is used as a biocontrol agent.

Antibacterial and Larvicidal Activity of Silver Nanoparticles Synthesized by the Leaf Extract of Andrographis serpyllifolia Wight

Green synthesizes of nanoparticles made a curiosity in the field of nanobiotechnology and they have a wide range of application. In this investigation, the leaf extract of Andrographis serpyllifolia was used to synthesis silver nanoparticles as a greener approach. These green silver nanoparticles characterized by UV-Spectrophotometer, Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), Transmission Electron Microscope (TEM), Zeta potential and particle size analysis. The silver nanoparticles were of spherical in nature with a minimum of 3.4 nm to a maximum of 71.6 nm with the average size of 24.1 nm. The larvicidal study showed that the AgNPs were highly active against the Culex quinquefasciatus larvae and the LC50 value observed was 68.889 µg/ml and LC90 value observed was 392.117. In addition, the antimicrobial study revealed that the A. serpyllifolia intervened AgNPs have shown prominent activity against the clinical pathogens viz., Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas fluorescens, and Escherichia coli. The maximum zone of inhibition observed against the S. pneumoniae was 21.33 ± 0.88 mm (75 µg/ml). Whereas, the lowest was observed against the S. aureus 14.66 ± 0.57 mm (25 µg/ml). The A. serpyllifolia mediated AgNPs demonstrated prominent bioactivity and used to control the emerging mosquito population and pathogenic microorganisms.

Toxicity of Silybum marianum and Nerium oleander extracts against Mosquito Larvae of Culex quinquefasciatus (Say)

Toxicity of two plant extracts against Culex quinquefasciatus mosquito larvae was measured in this work. The plants include the species; Silybum marianum and Nerium oleander. Their Lc50 and Lc90 after 4-hrs were evaluated against three instars of the mosquito. S. marianum Lc50 values were: 57, 214, and 379 ppm for the three instars respectively. S. marianum Lc90 values were: 2422, 2936, and 3161 ppm for the three instars respectively. N. oleander Lc50 values were: 161, 194, and 360 for the three instars respectively. N. oleander Lc90 values were: 1968, 2004, and 4203 for the three instars respectively. The results showed that the 1st instar larvae were more sensitive than the 2nd instar larvae, and this was more sensitive than the 3rd instar larvae. The results of recent work showed high correlation rate between logs of S. marianum and N. oleander concentrations and C. quinquefasciatus mortality percentage probits for all three larvae stages with high R values (0.911, 0.914 and 0.997) (0.993, 0.970 and 0.943) respectively. The aim of this study is to screen plant materials sources can be used in mosquito control.

Evaluation of Mosquito Larvicidal Activity of Ethanolic Extract of Grewia flavescens Juss. Whole Plant (Family: Tiliaceae) Against Culex quinquefasciatus

To evaluate the mosquito larvicidal activity on the ethanolic extract of Grewia flavescens juss (EEGF). Whole plant against Culex quinquefasciatus larvae. The larval mortality of 4th instar larvae of Culex quinquefasciatus after 24h and 48h of treatment which were tested separately in control and five test concentrations of 125 ppm, 250 ppm, 500 ppm,750 ppm, 1000 ppm concentration. The plant extract was screened to identify phytochemical bioactive compounds like alkaloids, flavonoids, saponins, tannins and glycosides. Different concentration of crude ethanolic extract of Grewia flavescensjuss. whole plant effectively showed larvicidal activity on Culex quinquefasciatus larvae. Based on the probit analysis values for 24h and 48h ethanolic extract of Grewia flavescens shows pronounced larvicidal activity. The LC50 and LC90 values of EEGF against mosquito 4th instar larvae of Culex quinquefasciatus was found 223.87 ppm and 724.43 ppm at 24hrs and for 48hrs the LC50 and LC90 values was found to be 181.97ppm and 374.76 ppm respectively. The preliminary phytochemical was performed in search of plants secondary metabolites which might be responsible for the larvicidal activity. The bioactive phytochemical classes which were identified and confirmed as alkaloids, flavonoids, saponins, tannins and glycosides. The ethanolic extract of this plant showed potent larvicidal activity and can be considered for further investigation. This experimental study was a pioneer attempt to establish Grewia flavescens juss. as a valuable resource of effective target specific natural mosquito larvicide. Keywords: Culex quinquefasciatus, larvicidal activity, ethanolic ext., phytochemical.

Cullen corylifolium (L.) Medik. Seed Extract, an Excellent System For Fabrication of Silver Nanoparticles and Their Multipotency Validation Against Different Mosquito Vectors and Human Cervical Cancer Cell Line

Development of therapeutic drugs for mosquito control and cancer is the need of the hour. This study highlights the fabrication of silver nanoparticles by incubating 45 ml of AgNO3 (0.5 mM) solution with 5 ml of Cullen corylifolium aqueous green seed extract at 60 ± 2 °C, 9 pH for 90 min. Ultraviolet–visible spectroscopy confirmed the synthesis of AgNPs by observing the absorption peak at 422 nm. Crystallographic nature of AgNPs was proved by XRD spectrum. FE-SEM images exhibited that most of AgNPs were spherical in shape with 20–60 nm average size. FT-IR spectrum revealed the existence of secondary metabolites that were involved in the reduction, stabilization and capping of AgNPs. The synthesized AgNPs exhibited the strong bioefficacy against the 3rd instar larvae of Anopheles stephensi (LC50, 6.03; LC90, 10.86 ppm), Aedes aegypti (LC50, 8.29; LC90, 13.75 ppm) and Culex quinquefasciatus (LC50, 16.55; LC90, 36.81 ppm) after 72 h of exposure. The AgNPs also exhibited strong anti-cancer activity having IC50 value 1.129 μg/ml after 24 h. These were proved to be non-toxic against non-target organism and normal cell line. These results suggest that synthesized AgNPs have strong larvicidal and anti-cancer potential and thus can be employed in cancer therapy, targeted drug delivery and drug designing.

A Novel Densovirus Isolated From the Asian Tiger Mosquito Displays Varied Pathogenicity Depending on Its Host Species.

Mosquito-borne viral diseases (MBVDs) continue to pose a significant global public health burden. Mosquito control remains a core intervention strategy in integrated mosquito management (IMM) programs to reduce the transmission of MBVDs. Mosquito densoviruses (MDVs) are mosquito-specific entomopathogenic viruses, and their attractive biological and pathogenic characteristics make MDVs potential biological control agents as alternatives to traditional chemical pesticides. However, different viral strains vary greatly in their pathogenicity against different mosquito species, which poses an obstacle for the wide application of MDVs in vector control. In this study, a novel MDV, Aedes albopictus densovirus-7 (AalDV-7), was isolated from field-collected Aedes albopictus in the dengue-endemic area of Guangzhou, China. The complete 4,048 nt genome of AalDV-7 was cloned and sequenced, and the transcription and translation of three open reading frames (ORFs) were characterized. Phylogenetic analysis indicated that AalDV-7 clustered with MDVs mostly isolated from indigenous mosquitoes. The pathogenicity of AalDV-7 to A. albopictus, Aedes aegypti, and Culex quinquefasciatus larvae was completely different, and the median lethal dose (LD50) of AalDV-7 in A. albopictus which was 109.48 genome equivalents per ml (geq/ml) was 12 and 46 times lower than those in A. aegypti (1010.56 geq/ml) and C. quinquefasciatus (1011.15 geq/ml). Furthermore, the median lethal time (LT50) value in A. albopictus (7.72 days) was 25% and 26% shorter than those in A. aegypti (10.24 days) and C. quinquefasciatus (10.42 days) at a titer of 1011 geq/ml. Furthermore, the mortality of AalDV-7-infected mosquitoes increased in a dose-dependent manner, and the highest mortality was found in A. albopictus larvae exposed to 1011 geq/ml AalDV-7 (82.00%). Sublethal effects analysis also showed that AalDV-7 infection significantly decreased pupation and emergence rates. The 1st–2nd instar larvae of all three mosquito species showed a near 100% infection rate, and the highest relative vial titer (305.97 ± 67.57 geq/ng) was observed in the 1st–2nd instar larvae of C. quinquefasciatus. These pathogenic characteristics make AalDV-7 a potential MBVDs control agent in China, whereas its negligible pathogenicity and high infection rate and viral dose in vivo make it a good candidate for gene delivery vectors in C. quinquefasciatus gene function analysis. In conclusion, the continuous discovery and isolation of new MDVs enrich the pool of mosquito entomopathogenic viruses and provide a variety of choices for optimal MDVs or combinations of MDVs to target certain mosquitoes.

A herbal oil in water nano-emulsion prepared through an ecofriendly approach affects two tropical disease vectors

Lippia alba (Mill.) N.E.Br. ex Britton & P. Wilson, Verbenaceae, is considered a great source of a bioactive volatile oil. Due to the wide range of known chemotypes, its chemical analysis is very important. Among the several activities of this volatile oil, a potential larvicidal action against Culicidae species is highlighted. However, the low water miscibility of volatile oils limits their application in aqueous media. Oil in water nano-emulsions are in the spotlight of novelty to solve this main problem. Thus, the aim of the present study was to obtain this nanostructured system with L. alba volatile oil (citral chemotype) and evaluate its larvicidal activity against Aedes aegypti and Culex quinquefasciatus larvae. The major compounds were geranial (30.02%) and neral (25.26%). Low mean droplet size (117.0 ± 1.0 nm) and low polydispersity index (0.231 ± 0.004) were observed and no major changes were observed after seven days of storage. LC50 values against C. quinquefasciatus and A. aegypti third-instar larvae were respectively 38.22 and 31.02 ppm, while LC90 values were, respectively, 59.42 and 47.19 ppm. The present study makes use of a low energy, solvent-free and ecofriendly method with reduced costs. Thus, this paper contributes significantly to phyto-nanobiotechnology of larvicidal agents, opening perspectives for the utilization of L. alba volatile oil in integrated practices of vector control.

Chemical constituents of thermal stress induced Ganoderma applantum (Per.) secondary metabolites on larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus and histopathological effects in mosquito larvae

Abstract Entomopathogenic fungus contains variety of secondary metabolites, which are known to have pharmacological and insecticidal properties. Stress plays an important role in production of toxic secondary metabolites. Thermal stress plays major role in production of toxic compounds. In the present study the toxicity of thermal temperatures induced G. applantum secondary metabolites were tested for larvicidal activities on Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. Our results show that after 24 h post treatment, stress induced G. applantum ethyl acetate extract produce strong larvicidal activity in An. stephensi (LC50: 53.035 mg/l),Cx. quinquefasciatus (LC50: 85.618 mg/l), and Ae. aegypti (LC50: 90.018 mg/l). G. applantum secondary metabolites were characterized using TLC and FT-IR. FT-IR shows two major functional groups which are, OH stretch and carboxylic groups. GC-MS analysis shows presence of two major compounds namely, Benzyl Chloroformates and hexyl nitro cyclohexene. Histopathological study shows that G.applantum extract, produce vacuolation in epithelial cells of midgut, far body and muscle tissues in mosquito larvae. Our overall findings suggest that thermal stress induced G. applantum culture, can produce virulent metabolites are toxic to mosquito larvae. These secondary metabolites can be used for effective, green pesticides for future mosquito control programs.

Mosquito larvicidal potential of hydroxy-2-methyl-4H-pyran-4-one (MALTOL) isolated from the methanol root extract of Senecio laetus Edgew. and its in-silico study

In the present study, hydroxy-2-methyl-4H-pyran-4-one was isolated from the methanol root extract of Senecio laetus and was identified by FT-IR, 1H, 13C NMR and GC-MS. The larvicidal potential of the compound 3-hydroxy-2-methyl-4H-pyran-4-one was evaluated against the 4th instar larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus at concentrations ranging from 20 to 1.25 ppm under laboratory conditions. The compound showed 100% mortality at 20 ppm against all the tested mosquitoe species and the LC50 and LC90 values were 1.22 and 7.25 ppm (An. stephensi), 2.10 and 99.84 ppm (Ae. aegypti) and 3.88 and 12.47 ppm (Cx. quinquefasciatus), respectively after 24 h of exposure period. In silico molecular docking study results reflects that hydroxy-2-methyl-4H-pyran-4-one compound showed highest binding affinity with OBP of Cx. quinquefasciatus (Glide energy score – 7.3 kcal/mol−1). The larvicidal activity of hydroxy-2-methyl-4H-pyran-4-one against tested mosquito species appears interesting and may be developed after toxicological and field evaluation.

Carlina oxide from Carlina acaulis root essential oil acts as a potent mosquito larvicide

Developing effective larvicides for mosquito control is being challenging due to the quick development of resistance in targeted vectors. Botanical products can help, due to their multiple mechanisms of action coupled with eco-friendly features. Carlina acaulis (Asteraceae) is an Alpine perennial herb used as a traditional remedy and food. Its root essential oil (EO) has antimicrobial and antitrypanosomal properties, and is currently listed among botanicals employable in food supplements. Its insecticidal activity has not been explored so far. Here, after analysing the C. acaulis EO chemical composition by GC–MS and NMR, we detected extremely high larvicidal activity of this EO and its main constituent, carlina oxide, against Culex quinquefasciatus larvae by using the standard WHO protocol. LC50 were 1.31 and 1.39 μg mL-1, respectively. 24-h exposure to both products triggered significant mortality rates for five days post-treatment. Larvicidal tests on a wider scale confirmed >95% larvicidal effectiveness of the EO and carlina oxide tested at 1.25 μg L-1. Their non-target impact was evaluated through experiments on Daphnia magna adults. Both showed significantly lower toxicity if compared to cypermethrin. To shed light on the modes of action, carlina oxide was tested for anti-acetylcholinesterase activity by the Ellman method, with lower performances over galantamine. A moderate antioxidant potential was observed using DPPH and ABTS assays, since it has a role for preserving the shelf-life of herbal-based insecticides. Finally, cytotoxicity on vertebrate cells was noted, testing carlina oxide on human dermis, HCT116 and MDA-MB231 cell lines by MTT assay. Overall, the outstanding toxicity of the tested products make them excellent candidates to develop novel mosquito larvicides for real-world applications.

Antibacterial and Larvicidal Activity of Fusarium proliferatum (YNS2) Whole Cell Biomass Mediated Copper Nanoparticles

Biosynthesis of metal nanoparticles using microorganisms is an emerging trend in nanotechnology and thus have wide application in agriculture and biomedical field due to its biocompatibility and ecofriendly nature. Our present study reports the synthesis of copper nanoparticles (CuNPs) using the whole cell biomass of F. proliferatum (YNS2) as a catalyst. The synthesized CuNPs were characterized by UV–visible spectroscopy, FTIR, XRD, FE-SEM, EDX and TEM analysis. The CuNPs showed prominent antimicrobial activity at different concentrations against the clinical pathogens viz., Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae and E. coli. In addition, we have evaluated the larvicidal activity of CuNPs against the larvae of Anophelex stephensi, Aedes aegypti and Culex quinquefasciatus. CuNPs showed the LC50 value of 39.25 µg/ml, 81.34 µg/ml and 21.84 µg/ml. A. aegypti, A. stephensi and C. quinquefasciatus respectively. Our present study clearly indicates that F. proliferatum (YNS2) whole cell mediated CuNPs are green, biodegradable, cheaper and a better alternative to synthetic antimicrobials and chemical insecticides.

Phytochemical composition and larvicidal activity of essential oils from herbal plants.

The essential oils (EOs) of Plectranthus amboinicus showed the highest larvicidal activity among four herbal plants studied and β-caryophyllene might be the major component responsible for its differential toxicity to the larvae of Culex quinquefasciatus and Aedes Aegypti. Mosquitoes act as vectors for many life-threatening diseases, including malaria, dengue fever, and Zika virus infection. Management of mosquitoes mainly relies on synthetic insecticides, which usually result in the rapid development of resistance; therefore, alternative mosquito control strategies are urgently needed. This study characterized the major component of essential oils (EOs) derived from the vegetative parts of four herbal plants and their larvicidal activity toward important mosquito vectors. The EOs were extracted by hydro-distillation and subjected to gas chromatography-mass spectrometry (GC-MS) analysis and a larvicidal activity assay toward Aedes aegypti, Ae. albopictus and Culex quinquefasciatus. In total, 14, 11, 11 and 9 compounds were identified from the EOs of Plectranthus amboinicus, Mentha requienii, Vitex rotundifolia and Crossostephium chinense, respectively. The EOs derived from four herbal plants exhibited remarkable larvicidal activity against the three mosquito species. In particular, the EOs of P. amboinicus showed the highest larvicidal activity, and the larvae of Cx. quinquefasciatus were more sensitive to the P. amboinicus EOs than that of Ae. Aegypti. Although carvacrol (61.53%) was the predominant constituent of the P. amboinicus EOs, its precursors, γ-terpinene (8.51%) and p-cymene (9.42%), exhibited the most larvicidal activity toward Ae. aegypti and Cx. quinquefasciatus. However, β-caryophyllene (12.79%) might be the major component responsible for the differential toxicity of the P. amboinicus EOs, as indicated by the significant differences in its LC50 values toward both mosquitoes. Information from these studies will benefit the incorporation of EOs into integrated vector management.

Larvicidal, Histopathological, Antibacterial Activity of Indigenous Fungus Penicillium sp. Against Aedes aegypti L and Culex quinquefasciatus (Say) (Diptera: Culicidae) and Its Acetylcholinesterase Inhibition and Toxicity Assessment of Zebrafish (Danio rerio).

Fungal metabolites are considered to be most efficient tools to overcome the issues related to insecticide resistance and environmental pollution. The present study focus on the evaluation of the mosquito larvicidal efficacy of metabolites of seven indigenous fungal isolates (Penicillium sp. Aspergillus niger, A. flavus, A. parasiticus, Rhizopus sp. Mucor sp. and Aspergillus sp.) on the larvae of Aedes aegypti and Culex quinquefasciatus under the laboratory condition. The preliminary screening of the isolate, Penicillium sp. showed better larvicidal effect when compared to other fungi. The fungus was grown on Potato Dextrose Broth (PDB) in the laboratory (at 25°C) and maintained in the relative humidity (at 76 ± 4% for 15 days). Larvicidal potency of mycelial ethyl acetate extract (MEAE) of Penicillium sp. was performed against 1st to 4th instars larvae of Ae. aegypti and Cx. quinquefasciatus using four different concentrations (100, 200, 300, and 500 μg/ml) that showed better larval mortality values (μg/ml) of LC50 = 6.554, 5.487, 6.874, 6.892, and the LC90 = 11.486, 10.366, 12.879, 13.865 for Ae. aegypti and LC50 = 7.000, 13.943, 18.129, 25.212 and the LC90 = 12.541, 23.761, 30.923, 41.696 for Cx. quinquefasciatus. Exposure of metabolite to larvae resulted in behavior changes i.e., excitation, up and down with aggressive movement, anal papillae biting behavior. Further, the larvae treated with Penicillium sp. metabolite exhibited significant reduction in the levels of acetylcholinesterase. The 4th instar mosquito larvae treated with the 500 μg/ml mycelia extract showed severe histological damages. During the antibacterial analysis of Penicillium sp.- mycelium the maximum growth inhibition zone was recorded in Shigella dysenteriae (31.2 mm) and Klebsiella pneumoniae (31.1 mm) followed by others. In addition, to check the toxicity of Penicillium sp. MEAE against embryos of Zebrafish, a model system, using different concentrations of metabolites (1.0, 0.5, 0.125 mg/ml, 30, 3.0, and 0.5 μg/ml) and life-stage parameters were observed at 124 hpf. Furthermore, the Fourier Transformed Infrared and GCMS spectrum analysis of mycelium reflected several chemical compounds. The outcome of the study clearly shows that Penicillium sp. metabolites could serve as an ideal eco-friendly, single-step and inexpensive source for the control of Ae. aegypti and Cx. quinquefasciatus larvae.

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

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, respectively. On the other hand, lower insecticidal activity was observed against larvae of the moth pest Spodoptera littoralis (LD50 of 268.9 µg·larva−1). It is worth noting that, when tested at LC90 concentration, BEO was significantly less toxic to aquatic microcrustacean Daphnia magna than the conventional insecticide α-cypermethrin. Finally, in the attempt to explore the BEO mode of action, we tested it for acetylcholinesterase (AChE) inhibitory properties using the Ellman method, obtaining negligible effects (IC50 = 0.45 mg·mL−1). Taken together, these results gave new insights into the potential of BEO as a future ingredient of botanical insecticides.

Evidence Based Efficacy of Selected Herbal Extracts Against Culex quinquefasciatus (Say) Larvae.

Chemical insecticides have some limitations in vectors control such as the emergence of resistance in vector mosquitoes to conventional synthetic insecticides. It aimed to evaluate the larvicidal efficacy and phytochemical potential of Azadirachta indica, Cymbopogon citratus and Allium sativum L. against ulex quinquefasciatus fourth instar larvae. The plants were screened and evaluated for their phytochemical composition and larvicidal effects on . quinquefasciatus larvae. The bioassay results showed that the effects were dependent on time and concentration of the extract used. Results showed the least lethal dose value for ethanolic extract of . citrates (72 h exposure) and the highest value for aqueous extract of A. indica (24 h exposure). Chi-square values were significant at p<0.05. Phytochemical analysis showed phytochemicals such as alkaloids, flavonoids, cardiac glycosides and resins in all the three plants. However, tannins were absent in A. indica and A. sativum, while balsam was only present in A. indica. Saponins, balsam and phenols were not found in A. sativum. Phenols were also absent in . citratus. Terpenes, steroids and resins were absent A. indica. Findings of this study revealed that these herbal extracts constitute an effective eco-friendly approach for the control of . quinquefasciatus larvae.

Mosquito larvicidal limonoids from the fruits of Chisocheton erythrocarpus Hiern

A phytochemical investigation on the fruits of Chisocheton erythrocarpus Hiern (Meliaceae) afforded four new limonoids, erythrocarpines F–H (1–3) and 14-deoxy-Δ1415-xyloccensin K (4), along with seven known compounds (5-11). Erythrocarpines 1–3 are phragmalin-type limonoids with an 1,29-oxymethylene bridge, while 4 is a mexicanolide-type limonoid possessing a rare 3β,8β-ether linkage. Mosquito larvicidal activity of the limonoids revealed that 4 and 5 were toxic to larvae of Aedes aegypti, Aedes albopictus and Culex Quinquefasciatus.