Aedes Aegypti Larvae Research Articles

Chemical composition, antimicrobial and larvicidal activities of essential oils of two Syzygium species from Vietnam.

The present study is the first to investigate the chemical composition, antimicrobial and larvicidal activities of the essential oils from the leaves of Syzygium attopeuense (Gagnep.) Merr. & L.M.Perry and Syzygium tonkinense (Gagnep.) Merr. & L.M.Perry collected in Vietnam. The essential oils were extracted by hydrodistillation and analyzed by GC and GC-MS. The study indicated the presence of a high percentage of sesquiterpenes in both investigated essential oils. The major components of S. attopeuense essential oil were bicyclogermacrene (24.26%), (E)-caryophyllene (11.72%), and (E)-β-ocimene (6.75%), whereas S. tonkinense essential oil was dominated by (E)-caryophyllene (80.80%). The antimicrobial activity of essential oils was evaluated by broth microdilution assay to determine the minimum inhibitory concentration (MIC) and median inhibitory concentration (IC50). Both essential oils exhibited remarkable inhibitory activity against all tested Gram-positive bacteria and yeast than Gram-negative bacteria. Among them, essential oils of S. attopeuense and S. tonkinense possessed the strongest activity against Enterococcus faecalis (MIC = 4.00 μg/mL; IC50 = 1.69 μg/mL) and Candida albicans (MIC = 16.00 μg/mL; IC50 = 8.67 μg/mL), respectively. Furthermore, the larvicidal activity of essential oils was tested using fourth-instar larvae of Aedes aegypti. Results from the larvicidal test revealed that both essential oils had an excellent inhibitory effect against A. aegypti larvae with LC50 values from 25.55 to 30.18 μg/mL and LC90 values from 33.00 to 39.01 μg/mL. Our findings demonstrate that the essential oil extracted from S. attopeuense and S. tonkinense are potential sources of natural antimicrobials and can act as inexpensive mosquito larvicidal agents.

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 LEAF AND ROOT EXTRACT OF ANTING-ANTING (Acalypha indica L.) ON MORTALITY OF AEDES AEGYPTI

Dengue Hemorrhagic Fever (DHF) is still one of the main public health problems and often has the status of an Extraordinary Event (KLB) with a high number of cases in a number of regions in Indonesia. Mosquito control with active chemical compounds can be difficult to decompose in nature and cause mosquitoes to become resistant to the next generation. As a substitute, the anting plant (Acalypha indica L.), which has been considered a weed, has bioactive compounds that can be used as natural insecticides. Biological control of vectors by using natural insecticides, a mixture of leaf and root extracts of the anting plant. The study used a mixture of leaf and root extracts of the anting plant using 7 treatments consisting of 5 serial concentrations of 250ppm, 500ppm, 750ppm, 800ppm, and 1000ppm, one positive control group using Aedes and one more negative control using Abate. The concentration that can kill 50% of Aedes aegypti larvae or (LC50) within 24 hours of exposure is 766,000 ppm. The plants contain secondary metabolites such as alkaloids, flavonoids, triterpenoids, and steroids which are toxic to the larvae of the Aedes aegypti mosquito.
 Keywords: Acalypha indica L., Aedes aeypti; Toxicity

Characterization of silver sulfide nanoparticles from actinobacterial strain (M10A62) and its toxicity against lepidopteran and dipterans insect species

Abstract In this research, cell-free extracts from magnesite mine-isolated actinobacterial strain (M10A62) were used to produce silver sulfide nanoparticles (Ag2SNPs). Streptomyces minutiscleroticus JX905302, actinobacteria capable of producing Ag2SNPs, was used to synthesize Ag2NPs. The UV–vis range was used to confirm the biosynthesized Ag2NPs; Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), and dynamic light scattering analysis were employed to characterize them further. Surface resonance plasma (SRP) for Ag2SNPs was obtained at 355 nm using UV–visible spectroscopy; FT-IR detected bimolecular and eventually microbial-reduced Ag2SNPs from S. minutiscleroticus culture extract. Furthermore, AFM and TEM analysis confirms that the synthesized Ag2SNPs were spherical in shape. Dynamic light scattering revealed a negatively charged Ag2NPs surface with a diameter of 10 nm. The XRD spectrum showed the crystalline nature of the obtained particles. EDAX revealed a pure crystalline nature, and a significant silver particle signal confirms the presence of metallic silver and sulfide nanoparticles together with the signals of Cu and C atoms. After 40 and 48 h of treatment at 150–200 µg·ml−1, Ag2SNPs produced the highest mortality in Spodoptera litura, H. armigera, Aedes aegypti, and Culex quinquefasciatus larvae. Hence, the biosynthesized Ag2SNPs may be useful for potential pest control in integrated pest management and vector control program as a safer, cost-effective, selective, and environmentally friendly approaches.

The toxicity of mixture of earring leaf and root extract (Acalypha indica L.) against Aedes aegypti mosquito larvae mortality

Tropical regions such as Indonesia are known to have optimal conditions of humidity and temperature that are very conductive for the survival of insects, including the Aedes aeypti mosquito which contains the Dengue virus. Until now, people still use chemical control using chemically active larvicides such as temephos. The continued use of temephos can cause the mosquito vector to become resistant to the next generation and be harmful to the environment. One way to control vectors can be done biologically by using natural insecticides, a mixture of leaf and root extracts of the earrings plant (Acalypha indica L.). The study used a mixture of leaf and root extracts of the earrings (Acalypha indica L.) plant using 7 treatments consisting of 5 serial concentrations of 250ppm, 500ppm, 750ppm, 800ppm and 1000ppm, 1 positive control using Aedes and 1 negative control using Abate. The concentration that can kill 50% of Aedes aegypti larvae or (LC50) within 24 hours of exposure is 766,000ppm. The plants contain secondary metabolites such as alkaloids, flavonoids, triterpenoids and steroids which is toxic to the larvae of the Aedes aegypti mosquito.

Potential Use of Papaya Flower Extract (Carica papaya Linn) for Aedes Aegypti Larvicide

Introduction: Temefos as a larvicide to prevent dengue hemorrhagic fever is known to be resistant to Aedes aegypti larvae in several regions in Indonesia. Therefore, alternative larvicides are needed. Papaya plants are one of the alternative solutions as papaya flowers contain secondary metabolite compounds that can kill Aedes aegypti larvae. This study aimed to determine the potential of papaya flower extract to be an Aedes aegypti larvicide.Methods : This study was a true experimental study with a posttest-only control group design, with 6 treatment groups namely 1%, 5%, 10%, 15%, and 20% extract concentrations (Experimental Group) and distilled water (Control Group). The experiment was repeated 4 times with a testing time of 24 hours. A total 600 Aedes aegypti instar larvae III/IV were used. Larvae toxicity was analyzed using Probit Analysis to determine the value of Lethal Concentration (LC) and Lethal Time (LT) and the Kruskall-Wallis test to determine the differences of larval deaths in each experimental group. Results: Results showed that the highest and the lowest average larval mortality was at 20% concentration (25 larvae) and 1% concentration (14.75 larvae), respectively. and values were 4.84% and 10.39%, while values of five concentrations were 115.74, 24.24, 23.41, 25.24, and 16.55 hours and values of five concentrations were 241.95, 29.42, 26.20, 32.24, and 24.48 hours. There was a difference in the number of larval deaths after 24 hours of treatment in the experimental group (p-value = 0.011).Conclusion: Papaya flower extract has the potential to be an Aedes aegypti larvicide with 20% concentration as the optimum dose. However, phytochemical screening needs to be done to determine the dominant papaya flower compounds act as Aedes aegypti larvicides.

Larvicidal activity of cloves as an alternative to chemical control in mosquito vectors in the Amazonia under laboratory conditions

Mosquito-borne diseases continue to be the main causes of death in many tropical countries. Among the infectious diseases transmitted by mosquitoes, malaria and dengue fever remain a major public health concern. Chemical control is the most widely used method for controlling and preventing mosquito-borne diseases. However, there are reports in the literature about resistance in populations due to the continuous use of chemical insecticides. In this sense, products of plant origin, such as plant extracts, essential oils and plant derivatives, have emerged as a promising alternative. In this study, bioassays were carried out to evaluate the activity of the aqueous and methanolic extracts of cloves (Syzigium aromaticum) in laboratory conditions against Anopheles darlingi and Aedes aegypti larvae. The bioassays carried out with An. darlingi showed CL50 values of 6.41 µg/mL for the methanolic extract and CL50 values of 5.65 µg/mL for the aqueous extract. Considering the bioassays with Ae. aegypti larvae (aqueous extract), the CL50 value was 78.81 µg/mL and the methanolic extract showed a CL50 value of 131.10 µg/mL. The larvicidal activity of the methanolic extract (CL50 131.10 µg/mL) against Ae. aegypti larvae was much lower than that obtained with An. darlingi. Comparing the two mosquito species, An. darlingi was more susceptible to the aqueous and methanolic extracts. However, when comparing the activity of the extracts against An. darlingi, it was found that the aqueous and methanolic extracts were active. With regard to Ae. aegypti larvae, they were more susceptible to the aqueous extract.

Regionality in vector control: effect of fluctuating temperature in the susceptibility of Aedes aegypti (Diptera: Culicidae) larvae to Pyriproxyfen.

Using Pyriproxyfen in controlling Aedes aegypti shows great potential considering its high competence in low dosages. As an endocrine disruptor, temperature can interfere with its efficiency, related to a decrease in larval emergence inhibition in hotter environments. However, previous studies have been performed at constant temperatures in the laboratory, which may not precisely reflect the environmental conditions in the field. The aim of this study was to assess the effect of the fluctuating temperatures in Pyriproxyfen efficiency on controlling Aedes aegypti larvae. We selected maximum and minimum temperatures from the Brazilian Meteorological Institute database from September to April for cities grouped by five regions. Five fluctuating temperatures (17-26; 20-28.5; 23-32.5; 23-30.5; 19.5-31 °C) were applied to bioassays assessing Pyriproxyfen efficiency in preventing adult emergence in Aedes aegypti larvae in five concentrations. In the lowest temperatures, the most diluted Pyriproxyfen treatment (0.0025 mg/L) was efficient in preventing the emergence of almost thrice the larvae than in the hottest temperatures (61% and 21%, respectively, p value = 0.00015). The concentration that inhibits the emergence of 50% of the population was lower than that preconized by the World Health Organization (0.01 mg/L) in all treatments, except for the hottest temperatures, for which we estimated 0.010 mg/L. We concluded that fluctuating temperatures in laboratory bioassays can provide a more realistic result to integrate the strategies in vector surveillance. For a country with continental proportions such as Brazil, considering regionalities is crucial to the rational use of insecticides.

THE EFFECT OF FRANGIPANI FLOWER (PLUMERIA ACUMINATA AIT) EXTRACT WITH GRANULE FORMULATION ON MORTALITY OF AEDES AEGYPTI LINN INSTAR III LARVAE

Dengue hemorrhagic fever is a disease transmitted through the bite of the Aedes aegypti mosquito and is widely found in Indonesia. The main key in dealing with Aedes aegypti mosquitoes is to control their spread and eradicate larvae. Vegetable larvicide frangipani flower extract formulated in granule form can be an alternative in vector control. The purpose of this study was to analyze the effect of frangipani flower (Plumeria acuminata Ait) extract with granule formulation as vegetable larvicide against Aedes aegypti Linn instar III larvae. The study was conducted in the laboratory of B2P2VRP Salatiga in 2015. The research method used was a pure experiment with 6 concentrations of 1.6%; 1.9%; 2.7%; 3.4%; 4.3% and 4.7% were accompanied by 4 repetitions. The total sample of larvae in the study amounted to 800 heads. Observations were made for 2,4,6 and 24 hours. Based on the results of study, the effective concentration of frangipani flower extract with granule formulation against the mortality of Aedes aegypti larvae is 4.7% because it is able to kill larvae 100%. The results of probit analysis obtained LC50 values of 1.572% and LC90 3.025%, while the LT50 value at an effective concentration of 4.7% was 2.902 or 3 hours and the LT90 value is 9.421 or 9 hours. The ANOVA test obtained p value = 0.000 (p<0.05). The results showed that there were significant differences in various concentrations of frangipani flower extract granules on the mortality of Aedes aegypti larvae. The conclusion was that the 4.7% concentration in the formulation of frangipani flower extract granule (Plumeria acuminata Ait) was effective as a vegetable larvicide

Unmasking lethal potential: investigating Leptolegnia chapmanii’s virulence against Aedes aegypti larvae

Unmasking lethal potential: investigating Leptolegnia chapmanii’s virulence against Aedes aegypti larvae

Susceptibility Test of Aedes aegypti Larvae to Temefos (Abate)

Dengue fever is an infectious disease transmitted by the Aedes aegypti mosquito. Temefos is a tool used in controlling Aedes aegypti larvae and its use for a long time without based on rules can cause resistance. This study aims to determine the susceptibility status of Aedes aegypti larvae to Temefos in the Ciamis and Cimaragas areas. The method of this research is experimental with samples obtained from residential areas in Ciamis and Cimaragas sub-districts then hatched into instar IV larvae at the Parasitology Laboratory of STIKes Muhamamadiyah Ciamis in May 2019. The results of the test on temefos 0.1 g showed that Aedes aegypti larvae from both regions obtained the results of Ciamis (100%) and Cimaragas (100%) sub-districts were still susceptible to temefos. From these results it can be concluded that the test larvae from both areas are still susceptible to temefos so that the tool can still be used as a larvicide, especially in controlling Aedes aegypti mosquitoes.

Prospects of Indigenous Bacillus subtilis Strain LS9.1 as a Potential Biocontrol Agent against Aedes aegypti Larvae

Biocontrol is one way that can be developed to overcome public health and agricultural problems. Biocontrol agents could be a microorganism, for example, from the Bacillus group. This study aims to determine the larvicidal toxicity of the Bacillus subtilis strain LS9.1 against Aedes aegypti larvae. The mode of action of the isolate caused larval death, which was detected with parasporal inclusions and secondary metabolites. Larvicidal toxicity with the bioassay method. Parasporal inclusion proteins were detected with the SDS-PAGE method. The Cry toxin coding gene with the PCR method and cell ultrastructure with transmission and scanning electron microscopy (TEM and SEM). The action of secondary metabolites was detected with hemolytic activity test. The isolate high toxicity to A. aegypti larvae. Parasporal inclusion proteins with molecular weights ranging from 72-7 kDa and the gene encoding a protein toxin in size 300 bp. The TEM and SEM results did not Cry-IV toxin. The hemolytic activity test showed a positive reaction correlated with biosurfactant production. Based on this study, the death of larvae is probably caused by secondary metabolites produced by Bacillus subtilis strain LS9.1. Thus, this isolate has the prospect of being an environmentally friendly biocontrol agent to disease vectors and insect pests.

Formulation, Dosage, and Exposure Time of Natural Substances in Controlling Aedes aegypti Larvae

The incidence of vector-borne diseases in Indonesia, particularly Dengue Hemorrhagic Fever (DHF), continues to escalate. This surge correlates with climate change, the extreme transition from hot to rainy seasons. The use of synthetic chemicals for control measures can also poses environmental risks; hence, there is a necessity to explore natural control methods by harnessing the biodiversity of plant species within the environment. This research aims to assess the effectiveness of botanical extract mixture on the mortality of Aedes aegypti larvae. Method: This study utilizes an experimental design with a complete factorial random arrangement, which aimed at elucidating the effectiveness of plant extract as a bio-larvacide against Aedes aegypti mosquitoes. The effectiveness is measured through larval mortality rates based on a formulated equation, with dosage and exposure time as the research variables. The research was conducted in the Environmental Health Departement Laboratory at Health Polytechnic of Tanjungkarang from March to July 2023. The observational sheet serves as the instrument The collected data are processed and analysed using ANOVA to discern variations in larva mortality based on the formula, linear regression is applied to explore the influence of dosage and exposure time on larva mortality. Result: The result of this study exhibits that the most efficacious formulations to terminate larvaes were determined to be the 9th, 10th, and 11th formulations. Furthermore, an extended exposure time correlates with the escalating rate of larval demise. The statistical model prosperously accounts for 88,59% of the variability in the response pertaining to Aedes larval mortality. Conclusion: This study discerns that individually, the formula, dosage, and exposure time, also demonstrates an impact on larval death. This study unveils that an insecticidal formula derived from soursop leaves yields a higher mortality effect compared to formulations based on other materials.

Microencapsulation of Bacillus thuringiensis strains for the control of Aedes aegypti

In this study, we investigated the microencapsulation of two strains of the entomopathogenic bacteria Bacillus thuringiensis (B. thuringiensis) (BtMA-750 and BtMA-1114), which are biopesticides of high toxicity for the mosquito vector Aedes aegypti. The encapsulation of different concentrations of microorganisms in starch microparticles was evaluated, and the inverse suspension polymerization technique was explored. It was possible to observe that the higher amounts of the biopesticide caused a slight decrease in the diameter of the particles; however, even when encapsulated, the biopesticide still presents an average diameter that is able to be consumed by the larvae of Aedes aegypti. Furthermore, it was noticed that the presence of both of the B. thuringiensis strains did not affect the thermal stability of the particles. The microencapsulated bacterial strains presented a high number of viable spores and preserved the expression of proteins with molecular masses corresponding to the insecticidal toxins Cry and Cyt, indicating that the encapsulation process was conducted satisfactorily. Finally, the encapsulated strains were tested against Ae. aegypti larvae and maintained 100% larval mortality even after 35 days. Therefore, microencapsulation of B. thuringiensis not only guarantees the bacterial activity, but also prolongs the action of the biopesticide. Collectively, such findings highlight the great potential of the new biopesticides, which may help to reduce the population indices of the mosquito vector Ae. aegypti via a sustainable and environment-friendly route.

Pathogenicity of microsclerotia from Metarhizium robertsii against Aedes aegypti larvae and antimicrobial peptides expression by mosquitoes during fungal-host interaction

Aedes aegypti is a vector of various disease-causing arboviruses. Chemical insecticide-based methods for mosquito control have increased resistance in different parts of the world. Thus, alternative control agents such as the entomopathogenic fungi are excellent candidates to control mosquitoes as part of an ecofriendly strategy. There is evidence of the potential of entomopathogenic fungal conidia and blastospores for biological control of eggs, larval and adult stages, as well as the pathogenicity of fungal microsclerotia against adults and eggs. However, there are no studies on the pathogenicity of microsclerotia against either aquatic insects or insects that develop part of their life cycle in the water, such as the A. aegypti larvae. In this study, we assayed the production of microsclerotia and their pathogenicity against A. aegypti larvae of two isolates of Metarhizium robertsii, i.e., CEP 423 isolated in La Plata, Argentina, and the model ARSEF 2575. Both isolates significantly reduced the survival of A. aegypti exposed to their microsclerotia. The fungus-larva interaction resulted in a delayed response in the host. This was evidenced by the expression of some humoral immune system genes such as defensins and cecropin on the 9th day post-infection, when the fungal infection was consolidated as a successful process that culminates in larvae mortality. In conclusion, M. robertsii microsclerotia are promising propagules to be applied as biological control agents against mosquitoes since they produce pathogenic conidia against A. aegypti larvae.

The Potential of Srigading Plants (Nyctanthes arbor-tristis) as Aedes aegypti Larvicides

Dengue Hemorrhagic Fever (DHF) is an endemic disease that causes high morbidity and mortality rates. The prevalence of DHF in Indonesia (2018) reached 24.75 per 100,000, and in South Kalimantan (2019) was 56.83 per 100,000 population. One of the efforts to control dengue vectors is the use of larvicides. The purpose of this study was to determine the potential of Srigading Plants (Nyctanthes arbor-tristis) as Aedes aegypti larvae as vectors of DHF in Wetlands. This study used a true experimental research design using the post-test-only controlled group design to determine the effectiveness of Srigading extract (Nyctanthes arbor-tristis) against the death of Aedes aegypti instar IV mosquito larvae. Based on the results, a significance value or p-value of 0.0001 0.05 was obtained. It indicated a significant difference between the number of mosquito larvae deaths and the concentration of Srigading extract given.

Green synthesis and biophysical characterization of silver and palladium nanoparticles using Laureliopsis philippiana: A potent eco-friendly larvicide with negligible impact on zebrafish (Danio rerio)

Green nanoparticles represent a sustainable and eco-friendly approach to developing larvicides targeted at controlling mosquito populations. These nanoparticles are synthesized using natural, non-toxic materials and environmentally benign processes, emphasizing their potential to combat mosquito larvae while minimizing adverse effects on the ecosystem. This approach aligns with the growing need for sustainable solutions in vector control, providing an effective alternative to traditional larvicides with reduced environmental impact. The aim of the present investigation we have utilized the leaf from Laureliopsis philippiana (LP) to synthesize silver (Ag) and palladium (Pd) nanoparticles (NPs) and studied toxicity on deadly disease vectors larvae of Aedes aegypti and Anopheles stephensi. Biosynthesized Ag and Pd NPs were extensively characterized through physical and chemical methods. Gas chromatography–mass spectrometry analysis of L. philippiana assisted in identifying the secondary metabolites of the extract's total flavonoid and phenolic compounds, which are in the reactants of the bio-reduction process during the production of NPs. The in-silico analysis was conducted on mosquito sterol carrier protein-2 (1PZ4) and mosquito odorant binding protein (2L2C). The biosynthesized Ag and Pd NPs revealed the UV absorption peak at 417 and 370 nm, and X-ray diffraction results showed the crystalline structure of NPs. At the same time, in transmission electron microscopy representation, the Ag and Pd NPs were spherical, clustered, and exhibited a noticeable average size of Ag NPs: 13.25 ± 2.53 nm and Pd NPs: 4.07 ± 1.64 nm. The biogenic Ag and Pd NPs showed concentration-dependent larvicidal mortality at 12 and 24-hour exposure with LC50 values of 29.596, 17.804, and 23.915, 14.878 µg/mL on Ae. aegypti and 23.946, 13.938, 19.457, and 12.876 µg/mL against An. stephensi, correspondingly. In-silico studies proved that Laureliopsine A and isoterpinolene showed significant docking scores compared to permethrin on mosquito proteins (1PZ4 and 2L2C). Besides, the LP-Ag and Pd NPs non-toxicity analysis was carried out on zebrafish (Danio rerio) embryos at 72 h post-fertilization. Overall, the findings clearly demonstrated the green synthesized Ag and Pd NPs from L. philippiana to develop environmentally secure and safe larvicides.

Laboratory scale evaluation of the feasibility of locally found bladderworts as biological agents to control dengue vector, Aedes aegypti in Sri Lanka

BackgroundThe carnivorous genus Utricularia also includes aquatic species that have the potential to trap a wide range of prey, leading its death due to anoxia. However, the effectiveness of such an approach with carnivorous plants for vector control has not been evaluated in Sri Lanka.MethodsEarly instar (i & ii) and late instar (iii & iv) larvae of Aedes aegypti were exposed to locally found bladderwort (U. aurea Lour and Utricularia sp.). The experimental design was set with 10 larvae (both early and late instars separately) in 250 mL of water with bladderworts containing approximately 100 bladders in plant segments of both species, separately. Each treatment and control were repeated 50 times. The survival status of larvae was recorded daily until death or adult emergence. The larvae found whole or partially inside the bladders were attributed to direct predation. The Cox-regression model and Mantel-Cox log rank test were carried out to assess the survival probabilities of larvae in the presence of two bladderworts separately.ResultsThe highest predation was observed when using early instar larvae in both U. aurea (97.8%) and Utricularia sp. (83.8%). The mortality caused due to predation by U. aurea was observed to be significantly higher according to the Mantel-Cox log-rank test (HR = 60.71, CI; 5.69–999.25, P = 0.004). The mortality rates of late instar stages of Ae. aegypti were observed to be lower in both U. aurea (82.6%) and Utricularia sp. (74.8%). Overall, the highest predation efficacy was detected from U. aurea (HR = 45.02; CI: 5.96–850.51, P = 0.017) even in late instar stages. The results suggested the cumulative predation in both plants on Ae. aegypti larvae was > 72%.ConclusionsUtricularia aurea is a competent predator of Ae. aegypti larvae. Further, it is recommended to evaluate the feasibility of this plant to be used in the field as a control intervention in integrated vector management programmes.

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.

Study of Antioxidant and Larvicidal Properties of Selected Medicinal Plants of Fringe Villages of Manas National Park, Assam, India

Background: Mosquito-borne diseases are among the major ailments of world affecting billions of people living in economically poor and developing countries. The development of insecticide resistance in mosquito vectors has forced the global community to look into alternative sources of medicines with better efficacy and less side effects. Plants with rich sources of metabolites have been explored extensively for mosquitocidal activity. The present study explored the antioxidant and larvicidal activities of five important plants traditionally used as mosquito repellent by tribal communities of fringe villages of Manas National Park of Assam. Methods: Methanolic crude extracts were prepared for all the plants following standard protocols. Phytochemical and antioxidant study was performed following the protocol published in recent publications. Larvicidal bioassay was carried out as per WHO protocol. Results: The study observed considerable phytochemical and antioxidant activity. Phenolics, flavonoid and antioxidant activity, were found to be highest in Cinnamomum tamala. The phenolic and flavonoid value ranged from 9.89 to 147.15µgGAE/mg and 4.32 to 28.43µgQE/mg plant extract, respectively. The IC50 for various antioxidant activities ranged from 27.94 to 114.15µg/mL (DPPH), 15.05 to 707.74µg/mL and 40.23 to 338.91µg/mL (TBARS). Similarly, C. tamala showed the strongest larvicidal activity with LC50 value of 3.11mg/mL in Aedes aegypti larvae. Conclusion: The present study observed that C. tamala leaves could be a good source of phytochemicals and antioxidant and larvicidal activity.