Instar Larvae Of Aedes Aegypti Research Articles

Eco-friendly bio-larvicidal and antimicrobial activity of isolated bioactive compound from Kurthia gibsonii (Bacillales).

The targeted organisms include mosquito vectors, bacterial pathogens and non-targeted organisms. Preliminary mosquito larvicidal activity was conducted using cell-free supernatants (CFSs) from 11 gut bacteria. Among them, the bacterium SS11 exhibited promising results and was identified as Kurthia gibsonii based on its 16S rRNA sequence (1350 bp). The diethyl ether extract (DEE) of K. gibsonii demonstrated significant larvicidal effects, with LC50 values of 5.59 µL/mL and 8.59 µL/mL for 3rd instar larvae of Aedes aegypti and 2nd instar larvae of Anopheles stephensi, respectively. Analysis of the DEE using FT-IR, and GC-MS revealed the presence of 16 functional groups, and 7 bioactive compounds, respectively. A molecular docking study identified GC-MS compounds against odorant receptors from A. aegypti and odorant-binding proteins from A. stephensi was performed to assess the interaction and binding affinity. Overall, these findings suggest that the bioactive compounds 2, 4, 6-tribromoaniline from the DEE of K. gibsonii hold potential as an environmentally compatible alternative for biocontrol purposes, and compounds 9-tricosene and didecyl phthalate can be used for mosquito traps.

Insecticidal Activity and Molecular Target by Morphological Analysis, RNAseq, and Molecular Docking of the Aryltetralin Lignan Lactone Helioxanthin, Isolated from Taiwania flousiana Gaussen.

Botanical insecticides are considered an environmentally friendly approach to insect control because they are easily biodegraded and cause less environmental pollution compared to traditional chemical pesticides. In this study, we reported the insecticidal activities of the ingredients from Taiwania flousiana Gaussen (T. flousiana). Five compounds, namely helioxanthin (C1), taiwanin E (C2), taiwanin H (C3), 7,4'-dimethylamentoflavone (C4), and 7,7″-di-O-methylamentoflavone (C5), were isolated and tested against the second, third, and fourth instar larvae of Aedes aegypti. Our results indicated that all five compounds showed insecticidal activities, and helioxanthin, which is an aryltetralin lignan lactone, was the most effective with LC50 values of 0.60, 2.82, and 3.12 mg/L, respectively, 48 h after application, with its activity against the second instar larvae similar to that of pyrethrin and better than that of rotenone. Further studies found that helioxanthin accumulated in the gastric cecum and the midgut and caused swelling of mitochondria with shallow matrices and fewer or disappeared crista. Additionally, our molecular mechanisms studies indicated that the significantly differentially expressed genes (DEGs) were mainly associated with mitochondria and the cuticle, among which the voltage-dependent anion-selective channel (VDAC) gene was the most down-regulated by helioxanthin, and VDAC is the potential target of helioxanthin by binding to specific amino acid residues (His 122 and Glu 147) via hydrogen bonds. We conclude that aryltetralin lignan lactone is a potential class of novel insecticides by targeting VDAC.

Larvicidal Efficiency of Citrus maxima against Aedes aegypti and Aedes albopictus

Mosquitoes transmit serious human diseases, causing millions of deaths every year and developed resistance to chemical insecticides resulting in rebounding vectorial capacity. Plants are the alternative sources of mosquito control agents. In the present study, various concentrations of 10, 20, 30, 40, and 50 mg of Citrus maxima (Brunnich) Merr. were tested against the third instar larvae of Aedes aegypti (Linn) and Aedes albopictus (Skuse). The highest larval mortality was found in the extract of C. maxima against third-instar larvae with P value = 0.0287. This study concluded that the increase in concentration of C. maxima extract increased the mortality of Aedes aegypti and Aedes albopictus.

An Efficient Access to Heteroaryl/Aryl-Annulated Pyridine Derivatives and a Study of Their Mosquito Larvicidal Activity Against Dengue Vector

AbstractWe report a convergent synthesis of heteroaryl/aryl-annulated pyridine and quinoline derivatives by a metal-free Povarov reaction. para-Toluene sulfonic acid was used as the catalyst in this reaction, which produced the products in good yields from the corresponding aromatic amines and ethyl vinyl ether. A pyridocoumarin and a pyridopyrimidine product were evaluated for their mosquito larvicidal activity against the third instar larvae of the dengue vector mosquito Aedes aegypti. Examination of morphological changes in the larvae showed damage to the target body part after treatment with both the pyridocoumarin and pyridopyrimidine products at the LC50 concentrations.

Bio-efficacies of different solvent extracts of Cosmos sulphureus on 3rd instar larvae of Aedes aegypti

Bio-efficacies of different solvent extracts of Cosmos sulphureus on 3rd instar larvae of Aedes aegypti

Toxicity of Elytraria Acaulis (L. F.) Lindau (Acanthaceae) to the Larvae of Vector Mosquitoes

Synthetic pesticides, which are non-biodegradable and have detrimental effects on the environment, non-targeted organisms, and human health, are often used to control mosquitoes. This situation fostered and prompted the creation of substitutes utilizing natural products like phytoextracts and phytochemicals. The current study was set out to determine the toxicity of leaf extracts from Elytraria acaulis on the early third instar larvae of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus at doses of 31.5, 62.5, 125, 250, 500 and 1000mg/L at 24 and 48 hours of exposure. All extracts, with the exception of aqueous, demonstrated potent larvicidal effectiveness with 100% larval death in all the three studied vector mosquitoes after 48 hours. The ethanol extract showed the maximum larvicidal activity and 100% larval mortality in Aedes aegypti after 24 hours, and its respective LC50 values against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus were 31.98, 560.29, 603.8108mg/L and 20.43, 46.13 and 60.08mg/L after 24 and 48 hours. The treated larvae exhibited extremely restless behaviour, including wiggling, sinking, floating, slowness, paralysis, sinking to the bottom of the glass beaker, and ultimately death. Qualitative phytochemical study of Elytraria acaulis leaves revealed the presence of alkaloids, flavonoids, glycosides, phenolics, saponins, steroids, tannins, terpenes, and terpenoids. The ethanolic extract GC-MS examination identified main phytocompounds, including imidazole, imidazolidinone, phytol, phytol acetate, octacosane, thymol 1-thiocarbonylimidazolide and methoxyacetic acid to determine the larvicidal mechanism of action and the cause of larval death. It is quite exciting to note, based on the results of the current investigation, that Elytraria acaulis leaf extracts, particularly ethanol extract, demonstrated good larvicidal efficacy. The present study documents the first report on the effectiveness of Elytraria acaulis ethanolic leaf extract against the larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus.

Larvicidal activity of green synthesized iron oxide nanoparticles using Grevillea robusta Cunn. leaf extract against vector mosquitoes and their characterization

Extensive fumigation of synthetic pesticides to control the mosquito vector during each post-monsoon season in Pakistan significantly enhanced the environmental contamination and extinction of beneficial insects from the urban ecosystems. In this context, the present study examined the larvicidal efficacy of green synthesized iron nanoparticles (IONPs), using an aqueous leaf extract of Grevillea robusta against the early 2nd and 4th instar larvae of Aedes aegypti and Anopheles stephensi in Pakistan. The prepared IONPs were characterized by UV–Vis spectrum, FTIR, X-ray diffraction, scanning electron microscopy, and energy-dispersive diffraction. Larvicidal bioassay was conducted at various concentrations (80, 160, 240, 320, and 400 ppm) of IONPs prepared from leaf extract of G. robusta, and readings were taken-every 12 h for two consecutive days. In vitro, larvicidal assay, G. robusta leaf extract IONPs exhibited high mortalities of 64–96% (LC50 = 259.07 ppm; LC90 = 443.92 ppm) for the second instar and 65–98% (LC50 = 238.05 ppm; LC90 = 433.93 ppm) for the fourth instar of Ae. aegypti, while in the case of An. stephensi 56–84% (LC50 = 297.96 ppm; LC90 = 528.69 ppm) for the second and 56–88% (LC50 = 292.72 ppm; LC90 = 514.00 ppm) mortality for fourth larvae at 12–48 h post-exposure times were observed respectively. Significant (p < 0.05) dose-dependent and exposure time-dependent trends were observed among the 2nd and 4th larvalinstar of An. stephensi and Ae. aegypti. However, both species showed similar response and observed no significant (p > 0.05) difference in percentage mortality between the vector mosquitoes An. stephensi and Ae. aegypti. Overall, this study demonstrates that the larvicidal efficacy of green synthesized IONPs at low concentrations can be an ideal eco-friendly and cost-effective biocontrol of vector mosquitoes' larvae of An. stephensi and Ae. aegypti.

Curcumin interferes with chitin synthesis in Aedes aegypti: a computational and experimental investigation.

Throughout history, vector-borne diseases have consistently posed significant challenges to human health. Among the strategies for vector control, chemical insecticides have seen widespread use since their inception. Nevertheless, their effectiveness is continually undermined by the steady growth of insecticide resistance within these vector populations. As such, the demand for more robust, efficient, and cost-effective natural insecticides has become increasingly pressing. One promising avenue of research focuses on chitin, a crucial structural component of mosquitoes' exoskeletons and other insects. Chitin not only provides protection and rigidity but also lends flexibility to the insect body. It undergoes substantial transformations during insect molting, a process known as ecdysis. Crucially, the production of chitin is facilitated by an enzyme known as chitin synthase, making it an attractive target for potential novel insecticides. Our recent study delved into the impacts of curcumin, a natural derivative of turmeric, on chitin synthesis and larval development in Aedes aegypti, a mosquito species known to transmit dengue and yellow fever. Our findings demonstrate that even sub-lethal amounts of curcumin can significantly reduce overall chitin content and disrupt the cuticle development in the 4th instar larvae of Aedes aegypti. Further to this, we utilized computational analyses to investigate how curcumin interacts with chitin synthase. Techniques such as molecular docking, pharmacophore feature mapping, and molecular dynamics (MD) simulations helped to illustrate that curcumin binds to the same site as polyoxin D, a recognized inhibitor of chitin synthase. These findings point to curcumin's potential as a natural, bioactive larvicide that targets chitin synthase in mosquitoes and potentially other insects.

Development of bioformulations using plant extracts for the control of dengue vector, Aedes aegypti

Dengue fever is a life-threatening illness in humans caused by the dengue virus belonging to Flaviviridae, affecting mainly in tropical and subtropical countries. The spread of this disease is through the dengue vector Aedes aegypti. Development of biodegradable, environmentally safe, low-cost larvicides is essential to overcome the resurgence effects of chemical insecticides. The present study included the development of bioformulations from larvicidal polar solvent extracts of the plant leaves. The solvents used for the extractions were ethyl acetate for Aloe vera (A), ethanol for Carica papaya (B), and methanol for Parthenium hysterophorous (C). Bioformulations in different combinations like A, B, C, A+B, B+C, C+A, and A+B+C with the concentrations of 50ppm, 100ppm, 150ppm, 200ppm, 250ppm and 300ppm were tested against the IVth instar larvae of Aedes aegypti and the results were recorded for every 24h 48h and 72h . The bioformulation extracts B+C (300ppm) showed 90 percent mortality of larvae after 72 h of treatment. It was concluded that the larvae's mortality was caused by the presence of bioactive compounds of B+C extracts. This formulation can be considered an effective biopesticide for the dengue vector Ae. aegypti IVth instar larvae.

Biosynthesis, mosquito larvicidal potential, and anticancer activities of gold nanoparticles from Acacia sinuata seed extract

Introduction and Aim: Worldwide, mosquitoes are the main vectors of many deadly diseases like malaria, dengue, chikungunya, etc., Anopheles stephensi mosquito which transmits malaria whereas dengue is transmitted mainly by mosquito Aedes aegypti. Current controlling methods such as chemical or microbial pesticides, repellents, biological control agents against mosquito larvae are not so effective. The leading cause of death worldwide is cancer. Nanotechnology can provide alternative effective methods for malaria, dengue and cancer control, diagnosis and treatment. This study investigated the biosynthesis of gold nanoparticles (AuNPs) from Acacia sinuata seed extract and their mosquito larvicidal potential was tested against Aedes aegypti, Anopheles stephensi larvae. The cytotoxic activity of NPs was also analyzed against human cancer cell lines osteosarcoma (MG-63) and colon adenocarcinoma (Caco-2). Materials and Methods: The biosynthesized NPs were confirmed and characterized by conventional techniques UV- visible spectroscopy, FTIR, XRD, HR-TEM, EDX and SAED. Results: The XRD demonstrated the NPs were face-centred, cubic, and crystalline in nature, EDX study confirmed elemental analysis of gold, SAED illustrated the crystalline nature. The HR-TEM studies revealed NPs shape which were mostly spherical and average size of 5.38nm-8.86nm. Third instar larvae of Aedes aegypti, Anopheles stephensi, were susceptible to the larvicidal effects of AuNPs. The synthesized NPs showed a dose-dependent cytotoxic effect against the Caco-2 and MG-63 cell lines, with IC50 (inhibitory concentrations) of 21.31± 0.15 ug/ml and 86.78± 0.23 ug/ml, respectively. Conclusion: These findings reveal that biosynthesized AuNPs have substantial larvicidal and anticancer properties, suggesting they could be used in mosquito control and cancer treatment.

Evaluation of Larvicidal Activity of Aqueous Extracts of Leaves, Root, Stem of Plumbago zeylanica Plant on Aedes aegypti

The purpose of this study was to determine the larvicidal effect of aqueous extracts of different parts of the Plumbago zeylanica plant on the dengue vector, Aedes aegypti. This research assessed P. zeylanica for its larvicide activity against A. aegypti larvae. Five different concentrations of hot and cold aqueous extracts of root, leaf, and stem powders of P. zeylanica were separately prepared. The larvicidal effect of these extracts was assessed against early 1st, 3rd, and 4th instar larvae of Aedes aegypti. Mosquito larvae were sampled, larval populations were monitored before and after application of aqueous extracts, and larval mortality was monitored after 12, 24, and 48 hours. Three trials were carried out under the same conditions. The percentage mortality of larvae in the sample was calculated, and the mean mortality was obtained for the 3 trials. Then the LC50 value was calculated according to the mean mortality with the SPSS package. The lowest LC50 values were obtained for the hot aqueous extracts on 1st instar larvae: root 122.74 mg/l, leaf 274.95 mg/l and stem 275.92 mg/l, 3rd instar larvae: root 129.37 mg/l, leaf 205.74 mg/l and stem 286.21 mg/l, 4th instar larvae: root 165.52 mg/l, leaf 216.89 mg/l and stem 329.94 mg/l and the root was found to have the highest larvicide activity. Finally, it was identified that by using 165.52 mg/l all three larval instar stages could be killed up to 50% and 90% with 280.921 mg/l. The present study reports that Plumbago zeylanica could serve as a potential larvicidal agent.

Green Nanobioinsecticide of a Brazilian endemic plant for the Aedes aegypti control

The search for sustainable alternatives for larval control of the Aedes aegypti (Diptera: Culicidae) mosquito, the vector that transmits Dengue Fever, is urgently needed in tropical and subtropical regions. This work aims to realize the chemical characterization of the essential oil from Xylopia ochrantha Mart. Leaves, prepare a stable nanoemulsion, and determine its hydrophilic-lipophilic balance (HLB) and larvicidal activity against the 3rd instar larvae of Aedes aegypti. Aerial dried parts of Xylopia ochrantha were collected at Restinga de Jurubatiba National Park (Brazil), and the essential oil was obtained by hydrodistillation using a Clevenger-type apparatus. The chemical characterization was done by gas chromatography, revealing germacrene D (17.8%), bicyclogermacrene (17.4%), and δ-elemene (13.9%) as the major compounds. The nanoemulsion prepared by the low-energy method presented a droplet size of 75.56 nm, a polydispersion index of 0.271, and a relative hydrophilic-lipophilic balance (HLB) value of 14.22. The LC50 was 192.5 μg/mL within 48 h against the 3rd instar Ae. Aegypti larvae. This study concluded that the nanoemulsion obtained from the essential oil of X. ochrantha leaves proved helpful for controlling this vector, which is responsible for causing diseases with a great impact on public health. Moreover, it gives visibility to the restinga, an important ecosystem. It points to the possibility of developing environmentally friendly products to help solve significant public health problems.

Toxicological assessment of lemongrass (Cymbopogon nardus L.) liquid waste: Biolarvicides againts the third instar larvae of Aedes aegypti

&lt;p&gt;Liquid waste generated from the distillation process of lemongrass (&lt;em&gt;Cymbopogon nardus&lt;/em&gt; L.) in a relatively short time will cause a foul odor, ammonia or phosphine that occurs due to the fermentation process. These problems can be minimized by reusing liquid waste of lemongrass (&lt;em&gt;C. nardus&lt;/em&gt; L.) into biolarvicides. This study aims to determine the value of Lethal Concentration 50 (LC50) from the liquid waste of lemongrass (&lt;em&gt;C. nardus&lt;/em&gt; L.) which can kill the third instar larvae of &lt;em&gt;A. aegypti&lt;/em&gt; mosquitoes for 24 hours. The liquid waste of lemongrass (&lt;em&gt;C. nardus&lt;/em&gt; L.) used in this study is waste obtained from the lemongrass (C. nardus L.) distillery located on Jalan Masjid Ulayat, Percut Sei Tuan District, Deli Serdang Regency, North Sumatra. A total of 10 mosquito larvae of &lt;em&gt;A. aegypti&lt;/em&gt; instar III were used for each different concentration of 6,982%, 7,607%, 8,287%, 9,027% and 9,833%. Each concentration consisted of five repetitions and was observed for 24 hours. After 24 hours, larvae that died were analyzed using probit analysis via SPSS 25. The results showed that the LC50 of lemongrass (&lt;em&gt;C. nardus&lt;/em&gt; L.) liquid waste can kill larvae for 24 hours was 8,763%.&lt;/p&gt;

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

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

GC-MS analysis and Larvicidal activity of Plectranthus amboinicus and Sphagneticola calendulacea leaf extract in relation to larvicidal activity against the mosquito Aedes aegypti

Many of the vector-borne diseases that harm humans and animals are transmitted by mosquitos. Malaria, filariasis, Japanese encephalitis, dengue fever, dengue haemorrhagic fever and yellow fever are all transmitted by mosquitos. Aedes aegypti and Anopheles stephensi are two mosquito species that are vectors. Yellow fever, dengue fever and chikungunya are all spread by Aedes aegypti, which is found across the tropical and subtropical zones. In India and other west Asian nations, A. stephensi is the predominant malaria vector. In both the Plectranthusamboinicus and Sphagneticolacalendulacea plant extracts, GC-MS analysis revealed 27 compounds. The mosquitocidal effectiveness of Plectranthusamboinicus and Sphagneticolacalendulacea ethyl acetate extracts against Aedes aegypti and Anopheles stephensi was investigated. Third and fourth instar larvae of Aedes aegypti and Aedes stephensi were killed after 24 and 48 hours of treatment in control by 50, 100, 120, 140, 150, 160, 180, 200, 250, 300 and 350 ppm concentrations respectively. The plant extracts were screened to identify the phytochemical bioactive compounds. A. aegypti was found to be most susceptible than the other species. LC50 and LC90 values of ethyl acetate extract were calculated against Aedes aegypti and Anopheles stephensi. The extracts of the plant showed potent larvicidal efficacy and can be considered for further investigation.

Phyto-mediated synthesis of MgO nanoparticles using Melia azedarach seed extract: Larvicidal and antioxidant activities

Plants contain some oxygen-containing phyto-components that possess medicinal values such as antioxidant and antipathogenic compounds. These oxygen-containing compounds such as flavonoids could be utilized in the synthesis of nanoparticles, thereby circumventing the use of toxic chemicals in materials synthesis. In this report, an eco-friendly green synthesis route has been employed to synthesize MgO nanoparticles (NPs) using the aqueous extract of Melia azedarach seed as the stabilizing agent. Different volumes (5, 10, and 20 mL) of the extract were used to synthesize nanoparticles represented as (b) MgONPs @5 mL, (c) MgONPs @10 mL (d) MgONPs @20 mL, respectively. The crystallinity and crystalline sizes were confirmed by an X-ray diffractometer, while the external and internal morphology of the NPs was evaluated using scanning and transmission electron microscopy. The band gap energies of the NPs were found to be in the range of 5.08 - 5.28 eV. Fourier-transform infrared spectroscopy was used to ascertain the type of functional groups that could be responsible for the synthesis. Larvicidal activity of the NPs was assessed against third instar larvae of Aedes aegypti and showed a dose-dependent activity against the larvae, with MgONPs @20 mL exhibiting the highest mortality of 86.68% at a concentration of 90 μg/mL and the least activity of 6.68% at 12.5 μg/mL concentration. Antioxidant assay of the NPs was evaluated, and the results indicated an increase in the percentage of radicals scavenged by the MgONPs compared to the plant extract. This was ascribed to the possible chelation of the radicals on the large surface area of the nanoparticles. The study shows the potential of M. azedarach seed-mediated MgO NPs to be utilized upon further study as high potent larvicidal and antioxidant agents in the development of novel nanoparticle-based biomedical agents.

Biogenic synthesis of silver nanoparticles mediated by the consortium comprising the marine fungal filtrates of Penicillium oxalicum and Fusarium hainanense along with their antimicrobial, antioxidant, larvicidal and anticancer potency.

To biosynthesize silver nanoparticles (AgNPs) using fungal isolates [DS-2 (Penicillium oxalicum) and DW-8 (Fusarium hainanense)] as well as their mixed cell-free filtrate (CFF) acting as a consortium (DSW-28) and their bio-potentials. The fungi (DS-2 and DW-8) were harvested and CFF was prepared. CFF of each fungus and their mixture were reacted with silver nitrate solution under dark conditions for the synthesis of AgNPs. The UV-Visible spectra determined the surface plasmon resonance at 438, 441 and 437 nm for the AgNPs synthesized by DS-2, DW-8 and DSW-28, respectively. The band gap energy was found between 2.21 and 2.24 eV which depicted their ability to act as a semiconductor. The TEM imaging revealed the spherical shape and small size of AgNPs. The XRD pattern exhibited the crystalline structure corresponding to their peaks. The FTIR spectra indicate the presence of different functional groups present on the surface of AgNPs. The broad-spectrum antimicrobial activity was exhibited by AgNPs. The AgNPs also act as an effective antioxidant by depicting their radical scavenging activity against DPPH. Moreover, the AgNPs also inhibited the growth of fourth instar larvae of Aedes aegypti and Culex quinquefasciatus more efficiently in a dose-dependent method. The biosynthesized AgNPs from DSW-28 showed a significant anticancer activity against MCF-7 cells. The silver nanoparticles synthesized by the CFF of two different fungi act synergistically in a consortium leading towards the production of silver nanoparticles with smaller size and higher bioactivity. The impressive bioactivity of the silver nanoparticles synthesized by the mixture of CFF of various fungi acting as a consortium recommends their prospective use in agriculture as well as in biomedical as an antimicrobial, antioxidant, larvicidal and anticancer agents in future.

The potential mosquitocidal activity of cry4A toxic region crystal protein gene from local isolates of Bacillus thuringiensis against Aedes aegypti

The present study was conducted to isolate Bacillus thuringiensis (B.t.) strains from different ecological regions of Pakistan and determined the mosquitocidal activity of cry4A crystal protein gene against the dipteran insects. Out of 25 B.t. isolates, 5 isolates were selected on the basis of toxicity and 4 were identified as Bacillus thuringiensis GCU-DAB-TK-04 (MN922746), GCU-DAB-TK-06 (MT032397), GCU-DAB-TK-09 (MN922747), and GCU-DAB-TK-13 (MT032398). GCU-DAB-TK-04 was found to be the most toxic strain against the 3rd instar larvae of Aedes aegypti. The presence of Cry 4A protein was confirmed by the amplification of cry4A gene (accession number MT001910) from GCU-DAB-TK-04. The highest spores toxicity was shown by GCU-DAB-TK-04 (LC50 = 104 μg/ml) while LC50 values of other strains were GCU-DAB-TK-13 (LC50 = 602 ± 0.43 μg/ml) GCU-DAB-TK-06 (LC50 = 812 ± 0.63 μg/ml), GCU-DAB-TK-12 (LC50 = 1230 ± 1.14 μg/ml), and GCU-DAB-TK-09 (LC50 = 7585 ± 1.17 μg/ml). Similarly, the highest toxicity of total cell protein was also shown by GCU-DAB-TK-04 (LC50=676 ± 0.53 μg/ml while LC50 values of other strains were GCU-DAB-TK-13 (LC50 = 724 ± 1.12 μg/ml), GCU-DAB-TK-06 (LC50 = 741 ± 0.64 μg/ml), GCU-DAB-TK-12 (LC50 = 912 ± 0.65 μg/ml), and GCU-DAB-TK-09 (LC50 = 1621 ± 1.13 μg/ml). The order of toxicity of B.t. strains was GCU-DAB-TK-04 > GCU-DAB-TK-13 > GCU-DAB-TK-06 > GCU-DAB-TK-12 > GCU-DAB-TK-09. Protein analysis showed that 130 kDa (probably Cry4A, B), 70 kDa (Cry4C, D) and 20 kDa (Cyt enhancer protein of Cry4) proteins were present in all B.t. strains. These B.t. strains have found great potential to grow into bio-insecticidal formulation for the eco-friendly control of mosquitoes.

Ovicidal and Larvicidal Activities of n-hexane Extract of Murraya paniculata (L.) Leaves against Aedes aegypti

Aims: Aedes aegypti is a widely distributed mosquito and the primary vector of several arboviral diseases attracting major global health concerns. This laboratory study accessed the ovicidal and larvicidal activities of n-hexane extract of Murraya paniculata (L.) Jack leaves on eggs and first instar larvae of Aedes aegypti.&#x0D; Study Design: Conventional bioassay,&#x0D; Place and Duration of Study: Department of Zoology, ETF Laboratory and Central research laboratory, College of Medicine, University of Lagos, Idi-araba, between February and July 2021.&#x0D; Methodology: Eggs and larvae were exposed to various quantities of test plant extract ranging from 20ppm to 80ppm for 72 hours at ambient laboratory temperature(30\(\pm\)0.570c). Probit analyses and analysis of variance were used to analyze the data.&#x0D; Results: Results revealed that the plant extract recorded the highest ovicidal activity of 61% at 80 ppm concentration against the eggs of Aedes aegypti, after 72 hours. The LC50 values of ovicidal and larvicidal activities at 72hrs were 85.162ppm and 80.270ppm respectively, there was a significant difference between the ovicidal and larvicidal activity of each concentration while mortality increased with increasing concentration.&#x0D; Conclusion: The results suggest that n-hexane extract of M. paniculata can be used as an environmentally friendly method for the control of Aedes aegypti.

Larvicidal and synergistic potentials of some plant extracts against Aedes aegypti

Introduction: The phytochemical analysis of the methanol extracts of four plants was determined and assayed for their larvicidal activities against the 4th instar larvae of Aedes aegypti, aiming to detect the promising ones. Method: The parts of the plants were sampled, dried out and powdered. The powdery parts of the plants were extracted with the help of methanol at room temperature for 3 days, with agitation. The extract was filtered and concentrated in vacuo. The resulting methanol extracts were tested against the 4th instar larvae of Aedes aegypti. Results: About sixty four percent (64.3%) of the tested extracts had moderate larvicidal activity after 24 hours. The leaf extract of Capsicum annuum was the most active at 1000 ppm. Conclusion: The parts of the plants assayed gave a dissimilar variety of larvicidal potentials, which can be utilized as a control manager for mosquitoes.