Culex Quinquefasciatus Larvae Research Articles

Rapid synthesis of copper nanoparticles using Nepeta cataria leaves: An eco-friendly management of disease-causing vectors and bacterial pathogens

Abstract Insecticides kill mosquitoes but damage other animals including humans. Eco-friendly metal nanoparticles may be a plant-based pesticide for vector control. Here, the copper nanoparticles (Cu NPs) synthesized from Nepeta catarialeaves have been investigated for their antibacterial and larvicidal properties. Fourier transforms infrared spectroscopy demonstrated that biochemicals reduced and stabilized nanoparticles by shifting peaks from 1,049 to 1,492 cm−1, and ultraviolet–visible spectrometry proved that produced Cu NPs had a peak at 550 nm. Transmission electron microscopic and scanning electron microscope showed that the particles are spherical and 23–29 nm in size. X-ray diffraction analysis shows that Cu NPs are crystalline. At a 100 µg·mL−1 concentration, Cu NPs exhibited a higher percentage of inhibition in the order of Escherichia coli ≫ Enterococcus faecalis ≫ Staphylococcus aureus. The lethal concentration (LC50) of the Cu NPs against the larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus was determined to be 60.63, 56.58, and 54.32 µg·mL−1, respectively. This ground-breaking study describes the biological production of Cu NPs utilizing N. cataria leaf extract for the first time. Based on these findings, the bio-synthesized Cu NPs and the aqueous extract of N. cataria may provide a potential alternative method for managing these vector populations.

Bioefficacy of ursolic acid and its derivatives isolated from Catharanthus roseus (L) G. Don leaf against Aedes aegypti, Culex quinquefasciatus, and Anopheles stephensi larvae.

The aim of the present study was to identify the active principle from Catharanthus roseus leaf using larvicidal bioassay against three mosquito species viz. Aedes aegypti, Culex quinquefasciatus, and Anopheles stephensi. Preliminary studies of the three successive extracts such as hexane, chloroform, and methanol against Ae. aegypti larvae showed that the chloroform extract was more active with LC50 and LC90 values of 40.09ppm and 189.15ppm respectively. Bioassay guided fractionation of the active chloroform extract resulted in the isolation of a triterpenoid (ursolic acid) as the active constituent. Three derivatives acetate, formate, and benzoate were prepared using this, and they were tested for their larvicidal activity against three mosquito species. The acetyl derivative was highly active against all the three species compared to the parent compound ursolic acid; the activities of benzoate and formate were higher than ursolic acid when tested against Cx. quinquefasciatus. This is the first report related to ursolic acid from C. roseus with mosquito larvicidal activity. The pure compound could be considered for medicinal and other pharmacological applications in future.

The phyto-compounds Fumaric acid, di(1-adamantylmethyl) ester and 2-Pentamethyldisilanyloxypentane Borne from Physalis longifolia Against Various Medical and Agronomic Pests

Objectives: To identify the major phytocompounds of Physalis longifolia leaf methanol extract and assess the ovicidal and larvicidal toxicity of target medical and agronomic pests of Aedes aegypti, Culex quinquefasciatus, Spodoptera litura and Helicoverpa armigera eggs and larvae. Methods: In this study, the phyto-compounds identification was made by GC-MS analysis. The selected phyto-compounds were applied towards eggs were tested various concentrations 4-16mg/ml and larvae were tested various concentrations 2- 200mg/ml of medical and agronomic pests. Overall mortality was examined using probit analysis to calculate LC50/LC90. Findings: The most common an Indian medicinal flora, Physalis longifolia leaf methanol extract and its derived major phyto-bioactive constituents Fumaric acid, di(1-adamantylmethyl) ester and 2-Pentamethyldisilanyloxypentane were authentically isolated by GCMS analysis. By phyto-chemical screening, more numbers of bio-active phytochemicals were occupied in high polar leaf extract. P. longifolia leaf methanol extract and its derived major phyto-bioactive constituents Fumaric acid, di(1-adamantylmethyl) ester and 2-Pentamethyldisilanyloxypentane were showed topper eggs toxicity above 90% which reached nearly 100% and the larval toxicity of LC50/ LC90 values were 11.01/18.73, 10.56/ 17.90, 14.19/ 26.59, 14.88/ 27.80 mg/ml and 10.91/ 18.75, 10.70/ 18.26, 15.77/ 29.29 and 14.86/26.55 mg/ml against the medical and agronomic pests of Ae. aegypti, Cx. quinquefasciatus, S. litura and H. armigera, respectively. Novelty: The biotoxicity of selected P. longifolia leaf methanol extract and its derived major phyto-bioactive constituents were well effective, environmental friendlier and produced least toxicity on non-target organisms. The medicinal flora, P. longifolia originated phyto-products could be a valuable farmer and ecofriendly bio-toxic weapon on medical and agronomic pests which promotelesser susceptible on non-target organisms. Keywords: Phytoproducts; Ecotoxicity; Physalis longifolia; Medical pest; Agronomic pest

Tree canopy cover affects basal resources and nutrient profiles of Aedes and Culex larvae in cemetery vases in New Orleans, Louisiana, United States.

Cemetery vases are important habitat for vector mosquito production, yet there is limited understanding on their food web dynamics and how they vary across environmental gradients. Tree cover is one factor that varies widely across cemeteries, and influence food webs by means of detrital inputs, temperature mediation, and light availability. Such information can be important for determining mosquito adult body size, fecundity, and competition outcomes, all of which may influence mosquito population and disease risk. This study evaluates the relationship between tree canopy cover and indicators of basal resources for Aede aegypti (L.), Aedes albopictuss (Skuse), and Culex quinquefasciatus (Say) larvae, such as stable isotopes (δ13C and δ15N) and nutrient stoichiometry in cemeteries of New Orleans, Louisiana (USA). Stable isotope values suggest that larvae feed directly on the Particulate Organic Matter (POM) suspended in the vase's water, and that POM composition influence the nutrient profiles of mosquito larvae. The POM of open canopy vases had higher δ13C values, than that of closed canopy vases indicating differences in relative proportion of basal carbon sources, with open canopy POM having a lower proportion of allochthonous carbon, and a higher proportion of authoctonous carbon. Accordingly, mosquito larvae collected from open canopy vases had higher δ13C values, and higher C:N than larvae from closed canopy vases. The results of this study show a shift in food web dynamics driven by canopy cover in cemetery vases that directly influence the nutrient profiles of mosquito larvae. The implications for mosquito ecology, and vector management are discussed.

Larvicidal and repellent efficacy evaluation of Calotropis procera against Aedes aegypti Linn and Culex quinquefasciatus (Diptera: Culicidae) mosquito species under laboratory condition

To evaluate the larvicidal efficacy of methanol extract of Calotropis procera the experiments were conducted against larvae of Aedes aegypti and Culex quinquefasciatus mosquito species. Third instar larvae of selected mosquitos species were exposed to various concentrations (50-200 ppm) and were evaluated in the laboratory. The morality observation of exposed larvae was recorded at 24 hrs. After treatment. LC values of the Calotropis procera leaf extract was determined following Probit analysis. The LC50 and LC90 values of Calotropis procera against Aedes aegypti and Culex quinquefasciatus larvae were recorded as 67.01, 95.92 and 138.49, 213.17 ppm, respectively. The Dhoop candle containg active ingredient Calotropis procera exhibited 80.00% and 67.92% repellency against Aedes aegypti and Culex quinquefasciatus mosquitoes, respectively. From the results it can be concluded the crude extract and Dhoop candle incorporating Calotropis procera offers an excellent potential for controlling and as well as repelling Aedes aegypti and Culex quinquefasciatus mosquitoes.

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.

Seaweed Sargassum wightii mediated preparation of TiO2 nanoparticles, larvicidal activity against malaria and filariasis vectors, and its effect on non-target organisms

Malaria and Lymphatic filariasis are considered significant public health concerns in several countries. As a researcher, controlling those mosquitos using safe and eco-friendly insecticides is essential. Thus, we aimed to explore the potential use of seaweed Sargassum wightii for the biosynthesis of TiO2 NPs and evaluate its efficiency in controlling disease-transmitting mosquito larvae (using Anopheles subpictus and Culex quinquefasciatus larvae as model systems (in vivo)) as well as its potential effect on non-target organisms (using Poecilia reticulata fish as an experimental model). XRD, FT-IR, SEM-EDAX, and TEM carried out the characterization of TiO2 NPs. It evaluated the larvicidal activity against the fourth instar larvae of A. subpictus and C. quinquefasciatus. The larvicidal mortality was observed after 24 h of exposure to S. wightii extract and TiO2 NPs. S. wightii synthesized TiO2 NPs show excellent activity against A. subpictus and C. quinquefasciatus (LC50 = 4.37 and 4.68; LC90 = 8.33 and 8.97; χ2 = 5.741 and 4.531) mg/L respectively. The GC-MS results indicate the presence of some important long-chain phytoconstituents like linoleic acid, palmitic acid, oleic acid methyl ester, and stearic acid, among others. Furthermore, when testing the possible toxicity of biosynthesized NPs in a non-target organism, no adverse effects were observed in Poecilia reticulata fish exposed for 24 h, considering the evaluated biomarkers. Thus, overall, our study results reveal that biosynthesized TiO2 NPs are an effective and exciting eco-friendly approach to controlling the A. subpictus and C. quinquefasciatus.

Entomopathogenic nematodes isolated from agricultural areas of Thailand and their activity against the larvae of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus (Diptera: Culicidae)

Entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis have been considered to be effective biological control agents for several insects. In this study, we isolated and identified EPNs from soil samples in agricultural areas of northern Thailand and evaluated their efficacy for controlling larvae of three mosquito vector species, Aedes aegypti, Ae. albopictus and Culex quinquefasciatus. A total of 51 of 1,000 soil samples were positive (5.1% prevalence) for EPNs, which were identified through sequencing of the rDNA and ITS to 37 Steinernema isolates (3.7%) and 14 Heterorhabditis isolates (1.4%). For the bioassay, the larvae of mosquitoes were exposed to Steinernema surkhetense (eALN6.3_TH), Steinernema lamjungense (eALN11.5_TH), Heterorhabditis indica (eACM14.2_TH) and Heterorhabditis bacteriophora (eALN18.2_TH). Heterorhabditis bacteriophora showed the highest efficacy against Ae. aegypti and Cx. quinquefasciatus. At 96 h after exposure, the mortality rates were 60.0 and 91.7%, respectively. The EPNs were observed in the dead mosquito larvae, which were mostly found in the thorax followed by the head and abdomen. Some EPNs were dead with melanization, and some were able to survive in the cavity of mosquito larvae. Our results show the low prevalence of EPN in agricultural areas of Thailand. Moreover, H. bacteriophora may be considered an alternative biocontrol agent for managing and controlling these vector mosquitoes.

Long-term storage does not affect the infectivity of entomopathogenic nematodes on insect hosts.

Entomopathogenic nematodes (EPNs) are effective biopesticides used in insect control. There are several formulations of entomopathogenic nematodes which are commercially available, but their popularity is low because the requirement of periodic release of stored entomopathogenic nematodes in field has reduced infectivity and is a constraint in large-scale repeated application of entomopathogenic nematodes in field. So, in order to overcome this impediment, the current study focuses on storage of entomopathogenic nematodes for a longer period of time using encapsulating beads. In this study, three EPNs, namely, Steinernema carpocapsae, Steinernema monticolum, and Rhabditis blumi, were encapsulated with Arabic gum and sodium alginate gel beads at different concentrations. Bio-efficacy of stored EPNs at different concentrations (50, 100, 200, 500, and 1000 infective juveniles (IJs)) in varying time intervals of 3, 6, 9, and 12weeks were tested against Culex quinquefasciatus larvae. The results show that, after 3weeks of storage, these entomopathogenic nematode species showed survival up to 96%, and in 12-week storage, survival rate was 50%. The virulence of the progeny that emerged from these stored entomopathogenic nematodes was similar to the fresh infective juveniles. The results of the present study show that Arabic gum-sodium alginate combination is a promising approach toward storing entomopathogenic nematodes. Furthermore, semi-field trials showed 70-90% larval mortality at a concentration of 3000 IJs (encapsulated and stored entomopathogenic nematodes in S. monticolum, S. carpocapsae, and R. blumi) on C. quinquefasciatus larvae. KEY POINTS: • Increased survival of stored EPNs (S. carpocapsae, S. monticolum, and R. blumi) in encapsulated gel using Arabic gum, sodium alginate, and yeast cells was assessed. • The efficacy was greater in stored EPNs at different concentrations from 3 to 12 weeks. • Semi-field trials of stored encapsulated EPNs are efficient in mosquito larval control.

Assessment of susceptible Culex quinquefasciatus larvae in Indonesia to different insecticides through metabolic enzymes and the histopathological midgut

Filariasis and virus diseases that are transmitted by Culex quinquefasciatus are still a global health problem. Control of mosquito vectors with synthetic insecticides causes resistance to these mosquitoes to insecticides so that detection of susceptibility of the mosquito larval stage to insecticides is important for evaluating mosquito control programs. The aim of this study was to evaluate the susceptibility of wild-caught Cx. quinquefasciatus larvae in Jakarta, Indonesia, following exposure to temephos, malathion, cypermethrin, and deltamethrin; this was done by examining the detoxifying enzyme activities and histological damage to the larval midgut. Cx. quinquefasciatus larvae were collected from five fields in Jakarta and exposed for 24 h to temephos (1.25, 6.25, 31.25, and 156.25 ppm), malathion (0.5 ppm), cypermethrin (0.25 ppm), and deltamethrin (0.35 ppm). The larvae were then examined for acetylcholinesterase (AChE), glutathione S-transferase (GST), and oxidase activities using biochemical methods. Histological damage to the larval midgut was examined using routine histopathological methods and transmission electron microscopy (TEM). After 24 h, temephos and deltamethrin led to 100% mortality in the Cx. quinquefasciatus larvae. Temephos and malathion significantly inhibited the activity of AChE, while cypermethrin and deltamethrin significantly inhibited oxidase activity. Histologically, all insecticides damaged the larval midgut, as indicated by irregularities in the epithelial cell (ECs), microvilli (Mv), food boluses (FBs), peritrophic membranes (PMs), and cracked epithelial layers (Ep). The TEM findings confirmed that temephos and cypermethrin damage to the midgut ECs included damage to the cell membrane, nucleus, nucleoli, mitochondria, and other cell organelles. Overall, Cx. quinquefasciatus larvae in Jakarta were completely susceptible to temephos and deltamethrin. Synthetic insecticides may kill Cx. quinquefasciatus larvae through their actions on the metabolic enzyme activities and histopathological midgut.

Larvicidal Efficacy of a Tropical Seaweed (Dictyota ciliolata) Extracts on Vectorial Mosquito Species and Non-Target Effect on Guppy Fish (Poecilia reticulata)

Extracts of seaweeds are promising candidates for eco-friendly, safe, and biodegradable larvicides and as alternatives to chemical larvicides used in mosquito control strategies. This study evaluated the larvicidal effects of Dictyota ciliolata on the mosquito larvae of Aedes aegypti, Anopheles gambiae, and Culex quinquefasciatus. The seaweed was extracted using ethanol and methanol. The larvicidal assays were conducted per WHO standards by exposing twenty 4th instar larvae to 100, 200, 300, 400, 500, and 600 mg/L of the derived extracts. The LC50 and LC95 values were obtained by calculating the probit values of the observed mortalities. LC50 of the ethanolic and methanolic extracts of Dictyota ciliolata against Anopheles gambiae larvae were 238.45 mg/L and 497.28 mg/L respectively; 179.02 mg/L and 224.96 mg/L respectively against Aedes aegypti, and 167.49 mg/L and 226.69 mg/L respectively for Culex quinquefasciatus. The results established that ethanolic and methanolic seaweed extracts were most influential on Culex quinquefasciatus followed by Aedes aegypti and Anopheles gambiae. Although mortalities were recorded for Poecilia reticulata, such may not be enough to de-emphasize the observed larvicidal potentials of Dictyota ciliolata as some other factors could have been responsible for the said mortalities in the non-target species.

Phytosynthesis of Silver Nanoparticle (AgNPs) Using Aqueous Leaf Extract of Knoxia sumatrensis (Retz.) DC. and Their Multi-Potent Biological Activity: An Eco-Friendly Approach.

Green synthesis of silver nanoparticles (AgNPs) has gained greater interest among chemists and researchers in this current scenario. The present research investigates the larvicidal and anti-proliferation activity of AgNPs derived from Knoxia sumatrensis aqueous leaf extract (K. sumatrensis-ALE) as a potential capping and reducing candidate. The synthesized AgNPs were characterized through-UV-spectra absorption peak at 425 nm. The XRD and FT-IR studied displayed the crystalline nature and presence of functional groups in prepared samples. FE-SEM showed the hexagonal shape of NPs with the size of 7.73 to 32.84 nm. The synthesized AgNPs displayed superior antioxidant and anti-proliferative activity (IC50 53.29 µg/mL) of breast cancer cell line (MCF-7). Additionally, larvicidal activity against mosquito vector Culex quinquefasciatus larvae delivered (LC50-0.40, mg/L, and LC90-15.83) significant mortality rate post treatment with synthesized AgNPs. Overall, the present research illustrates that the synthesized AgNPs have high biological potential and present a perfect contender in the pharmacological and mosquitocidal arena.

Evaluation of mosquito larvicidal potency of leaf and fruit extracts of Olax scandens Roxb. against the vectors of dengue and lymphatic filariasis

The emergence of resistance in insect vectors and destabilization of the ecosystem by excessive use of synthetic insecticides suggest an environmentally familiar alternative to suppress vector-borne diseases. Nowadays, phytochemicals play a major role in the biocontrol of vector populations. The present work evaluated the mosquito larvicidal potential of leaf and fruit extracts of Olax scandens Roxb. against the 3rd instar larvae of Aedes albopictus and Culex quinquefasciatus. The result of this assay indicated that the LC50 values of crude extracts of leaf and fruit 72 h post-exposure against Aedes albopictus larvae are 0.496%, and 0.879% respectively. While, LC50 values of leaf and fruit crude extracts against Culex quinquefasciatus are 0.354%, and 0.572% respectively in 72 h of exposure. Both extracts were able to create adverse effects in both the mosquito species and gave satisfactory mortality. Regarding the effectiveness of Olax scandens, the experiment reveals larvicidal toxicity of fruit extract is higher than the leaf extract and toxicity against the larvae of Culex quinquefasciatus is higher than the larvae of Aedes albopictus. The plant, Olax scandens can be used as a potent, plant-derived, eco-friendly, broad-spectrum mosquitocidal agent and it may become an important tool in mosquito management programs.

Evaluation of pure camphor (C10H16O) against wild-caught Culex quinquefasciatus larvae in East Jakarta, Indonesia: Detoxification enzymes and histopathological midgut

Filariasis, transmitted by the lymphatic filariasis vector Culex quinquefasciatus, is still a global public health issue. Resistance to Cx. quinquefasciatus is caused by the eradication of filariasis with synthetic insecticides. The aim of the study was to evaluate the toxicity of pure camphor on Cx. quinquefasciatus, with a focus on detoxifying enzymes and midgut histopathological abnormalities. Cx. quinquefasciatus larvae are field-collected wild-strain larvae. The WHO protocol was followed for the larval bioassays. Pure camphor concentrations of 0.5, 1.5, 10.5, 25.5, and 50 ppm were applied to larvae for 24, 48, and 72 h, with 5 replications. The biochemical method was used to test detoxification enzymes such as acetylcholinesterase (AChE), glutathione S-transferase (GST), and oxidase. The routine histopathological examination was performed on the larvae's histopathological midguts. At 48 h, pure camphor caused 100% mortality of Cx. quinquefasciatus larvae. LC50 and LC90 values were found to be 2.32 and 12.40 ppm respectively. AChE and oxidase activity were both significantly lower (p

Antifeedant and larvicidal activity of bioactive compounds isolated from entomopathogenic fungi Penicillium sp. for the control of agricultural and medically important insect pest (Spodoptera litura and Culex quinquefasciatus)

The use of chemical insecticides in agriculture has posed several challenges to environment and ecosystem health. Pesticides of biological origin are considered to be suitable for sustainable environment. In the present study bioactive compounds from Penicillium sp. was isolated and tested for insecticidal activity on Spodoptera litura and Culex quinquefasciatus larvae. Ethyl acetate extract of Penicillium sp. were characterized using GC–MS and FT-IR analysis. GC–MS analysis showed 20 different bioactive compounds namely, Propanoic acid, ethyl ester, Acetic Acid, Propyl Ester, Isopentyl Acetate, Acetic Acid, 2-Methylpropyl Ester, Behenic alcohol, 1-Hexadecene, 1-Octadecene, 1-Hexacosanol, n-Hexadecanoic acid, 1-Tetradecanol, 1-Dodecene, Tetrydamine, and Octadecanoic acid. The presence of functional groups such as, chloroalkanes, sulfonates, phosphines, amines, carboxylic acid, alkanes, and isocyanates was identified by using FTIR. Ethyl acetate extract of Penicillium sp., were tested for larvicidal activity on Spodoptera litura and Culex quinquefasciatus larvae showed significant larval mortality after 48 h of exposure with LC50: 72.205 mg/ml: LC90: 282.783 mg/ml and LC50: 94.701 mg/ml: LC90:475.049 mg/ml respectively. High antifeedant activity was observed in 300 μg/ml at 48 h of crude extract exposure. The present study concludes that Penicillium sp., secondary metabolites are effective for control of Spodoptera litura and Culex quinquefasciatus larvae.

Purification, characterization and toxicity assessment of PirAB toxins from Photorhabdus akhurstii subsp. akhurstii K-1

Photorhabdus insect related proteins A & B (PirA, PirB) from Photorhabdus and Xenorhabdus bacteria exhibit both oral and injectable toxicity against lepidopteran and dipteran insect pest. The pirA, pirAt (encoding 6 N-terminal truncated PirA), pirB genes, pirA-pirB (with ERIC sequences), pirA-pirB-mERIC (modified pirA-pirB with mutated ERIC sequences) and polycistronic-pirAB were cloned and expressed in Escherichia coli. However, PirA protein was expressed in insoluble form and therefore the pirA gene was modified to produce PirAt. Moreover, pirA-pirB-mERIC, polycistronic-pirAB and co-transformed pirA/pirB genes were not expressed in the studied prokaryotic expression systems. None of the single purified proteins or mixtures of the individually expressed and purified proteins were toxic to mosquito larvae of Aedes aegypti and Culex quinquefasciatus. However, PirA-PirB protein mixtures purified from pirA-pirB operon plasmid were toxic to A. aegypti and C. quinquefasciatus larvae with LC50 values of 991 and 614 ng/ml, respectively. The presence of ERIC sequences between the two orfs of the pirA-pirB operon could help to obtain the proteins in biologically active form. Further, results confirm that PirA-PirB proteins of P. akhurstii subsp. akhurstii K-1 are binary insecticidal toxins and ERIC sequences could play an important role in expression of Pir proteins. Reports of biophysical characterization of individually purified PirAt, PirB and expressed PirA-PirB toxin mixture could provide the structural insight into these proteins.

RETRACTED: Cladophialophora bantiana metabolites are efficient in the larvicidal and ovicidal control of Aedes aegypti, and Culex quinquefasciatus and have low toxicity in zebrafish embryo

Mosquitoes' current insecticide resistance status in available public health insecticides is a serious threat to mosquito control initiatives. Microbe-based control agents provide an alternative to conventional pesticides and insecticides, as they can be more targeted than synthetic insecticides. The present study was focused on identifying and investigating the mosquitocidal potential of Cladophialophora bantiana, an endophytic fungus isolated from Opuntia ficus-indica. The Cladophialophora species was identified through phylogenetic analysis of the rDNA sequence. The isolated fungus was first evaluated for its potential to produce metabolites against Aedes aegpti and Culex quinquefasciatus larvae in the 1-4th instar. The secondary metabolites of mycelium extract were assessed at various test doses (100, 200, 300, 400, and 500 μg/mL) in independent bioassays for each instar of selected mosquito larvae. After 48 h of exposure, A. aegypti expressed LC50 values of 13.069, 18.085, 9.554, and 11.717 μg/mL and LC90 = 25.702, 30.860, 17.275, and 19.601 μg/mL; followed by C. quinquefasciatus LC50 = 14.467, 11.766, 5.934, and 7.589 μg/mL, and LC90 = 29.529, 20.767, 11.192, and 13.296 μg/mL. The mean % of ovicidal bioassay was recorded 120 h after exposure. The hatchability (%) was proportional to mycelia metabolite concentration. The enzymatic level of acetylcholinesterase in fungal mycelial metabolite treated 4th instar larvae indicated a dose-dependent pattern. The GC–MS profile of C. bantiana extracts identified five of the most abundant compounds, namely cyclobutane, trans-3-undecene-1,5-diyne, 1-bromo-2-chloro, propane, 1,2,3-trichloro-2-methyl-, 5,5,10,10-tetrachlorotricyclo, and phenol, which had the killing effect in mosquitoes. Furthermore, the C. bantiana fungus ethyl acetate extracts had a strong larvicidal action on A. aegypti and C. quinquefasciatus. Finally, the toxicity test on zebrafish embryos revealed the induction of malformations only at concentrations above 1 mg/mL. Therefore, our study pioneered evidence that C. bantiana fungal metabolites effectively control A. aegypti and C. qunquefasciastus and show less lethality in zebrafish embryos at concentrations up to 500 μg/mL.

The Influence of Portulaca Oleracea L. Leaves Extracts on the Histoarchitecture of Culex Quinquefasciatus and Anopheles Stephensi Larvae

Mosquito is a big threat to the human health. Mosquito-borne diseases cause millions of death to the human beings. Hence, a permanent solution is eagerly to be established to control its excessive growth in stagnant water. Portulaca oleracea Linn is a natural larvicidal agent, which contains active ingredients such as linolenic acid, linoleic acid (omega-3 fatty acids). These bioactive compounds may be responsible for its larvicidal properties on mosquito. The present study is focussed on identifying the bioactive compounds, such as linolenic acid, through GC–MS, and analyzing the larvicidal efficacy of Portulaca oleracea L. against Culex quinquefasciatus and Anopheles stephensi larvae. Preliminary phytochemical analysis, total protein content, total carbohydrate content, total phenol content, total flavonoid content and GC–MS analysis exhibited the presence of rich phytoconstituents in Portulaca oleracea . DPPH analysis was carried out to analyze the antioxidant potential of plant extract. Larvicidal activity and histological change were detected to evaluate the efficacy of Portulaca oleracea L . on the Culex quinquefasciatus and Anopheles stephensi larvae. Aqueous and ethanol leaf extracts of Portulaca oleracea L . against both Culex quinquefasciatus and Anopheles stephensi larvae, showed a very good larvicidal activity at 500 µg/mL among the various concentrations. Histological damages of mosquito larvae were observed when treated with the Portulaca oleracea L . extract, and provided further evidence for its larvicidal activity. This study concluded that the plant Portulaca oleracea L . contained many useful bioactive compounds, can be a strong larvicidal agent against both Culex quinquefasciatus and Anopheles stephensi larvae. The molecular mechanism for the larvicidal activity will be identified in future studies.

Biocidal action, characterization, and molecular docking of Mentha piperita (Lamiaceae) leaves extract against Culex quinquefasciatus (Diptera: Culicidae) larvae.

Mosquitoes are found in tropical and subtropical areas and are the carriers of a variety of diseases that are harmful to people’s health. e.g., malaria, filariasis, chikungunya, dengue fever, etc. Although several insecticides are available, however, due to insect resistance and environmental hazards, more eco-friendly chemicals are needed for insect control. So, the current research was planned to explore the prospective of Mentha piperita to be used for the formulation of larvicides against mosquito Culex quinquefasciatus. The ethanolic and water extracts of M. piperita leaves were prepared using the soxhlet apparatus. The extracts were dried and subjected to prepare five concentrations multiple of 80 ppm. Each concentration was applied for its larvicidal efficacy setting an experiment (in triplicate) in plastic containers of 1000 ml with extracts, 30 larvae of all four instars separately, and fed with dog biscuits along with controls. Observations were taken after each 12 hrs. till 72 hrs. The antioxidant perspective of M. piperita was determined by DPPH radical scavenging, total antioxidant capacity, and ferric reducing power assays. Using brine shrimp lethality bioactivity, the cytotoxic study was perceived. Standard techniques were used to classify the M. piperita extract using preliminary qualitative and quantitative phytochemicals, UV-Vis spectroscopy, FT-IR, and GC-MS analysis. M. piperita ethanolic leaves extract after 24 hrs. of exposure in 400 ppm showed 93% (LC50 = 208.976 ppm) mortality in ethanolic extract and 80% (LC90 = 246.900 ppm) in the water extract. In treated larvae, biochemical examination revealed a substantial (P<0.05) decrease in proteins, carbohydrates, and fat contents. The ethanol extract of M. piperita was the most efficient, killing brine shrimp nauplii in 50% to 90% of cases. TAC (125.4 3.5gAAE/mg DW) and FRP (378.1 1.0gAAE/mg DW) were highest in the ethanolic extract of M. piperita. The presence of medicinally active components such as alkaloids, carbohydrates, flavonoids, and others in M. piperita leaves extract in ethanol was discovered. The UV-Vis spectrum showed two peaks at 209.509 and 282.814 nm with the absorption of 2.338 and 0.796 respectively. The FT-IR consequences exhibited the occurrence of alcohols, alkanes, aldehyde, aromatic rings, ether linkage, ester, and halo- compounds. The GC-MS analysis according to peak (%) area and retention time showed ten phytochemicals consisting of six major and four minor compounds. Among all the compounds, 1, 2-benzene dicarboxylic acid, and 3-ethyl-5, 5-dimethyl -6-phenyl bound well to the NS3 protease domain with PDB ID: 2FOM. Hence, for the prevention of health hazards and mosquito control, M. Piperita is a potential source of chemicals for insecticide formulation.

Effect of hot water leaf and bark extract of Swietenia mahagoni against the Culex quinquefasciatus and Aedes aegypti larvae

Mosquito larvae control is essential to prevent mosquito borne diseases such as dengue, Zika, filariasis and chikungunya. Plant extract has the larvicidal properties with less toxicity to other living creatures and no resistance compared to synthetic chemical pesticides. Effect of hot water leaf and bark extract of a forest tree species (Swietenia mahagoni) against the 3rd instar larvae of Culex quinquefasciatus and Aedes aegypti was studied in vitro using five different concentrations (1-5%) of hot water leaf and bark extracts of Swietenia mahagoni. It was observed that, 5% concentrated hot water leaf extract was the most toxic killing 70% larvae of Culex quiquefasciatus and 50% larvae of Aedesa egypti after 24 hours exposure. Similarly, 5% hot water bark extracts killed 65% and 55% of Culex quiquefasciatus and Aedes aegypti larvae respectively. The minimum LC50, LC90 and LC95 values of hot water leaf extract of Swietenia mahagoni against Culex quinquefasciatus Say and Aedes aegypti (L.) with 95% confidence limits were 2.662, 6.968, 8.70 and 2.128, 4.964, 6.054 respectively after 72 hours of exposure. In hot water bark extract of Swietenia mahagoni against Culex quinquefasciatus Say and Aedes aegypti (L.) with 95% confidence limits after 72 hours of exposure minimum LC50, LC90 and LC95values were 1.780, 6.540, 9.458 and 1.370, 4.570, 6.430. The present investigation revealed the possible utilization of hot water leaf and bark extract of Swietenia mahagoni to control mosquito borne disease. Further study is needed to know the active ingredients of the leaf and bark extract of the experimented plant. Asian J. Med. Biol. Res. 2022, 8 (2), 94-102