Aedes Aegypti Larvae Research Articles

FAKTOR- FAKTOR YANG BERHUBUNGAN DENGAN KEBERADAAN JENTIK NYAMUK AEDES AEGYPTI

The existence of Aedes aegypti larvae is evidence of the discovery of a population of Aedes aegypti mosquitoes that influence the occurrence of Dengue Hemorrhagic Fever. The larvae-free rate in Labuh Baru Timur Subdistrict was found to be 85%, which shows that it has not reached the national standard above or equal to 95%. The research aimed to determine the factors related to the presence of Aedes aegypti mosquito larvae in Labuh Baru Timur Subdistrict, the working area of ​​the Payung Sekaki Community Health Center, Pekanbaru City in 2023. This research method was quantitative using Observational Analytical with a cross-sectional design. The research was carried out in February - July 2023. The sampling technique was quota sampling of 100 heads of families. The data analysis used is univariate and bivariate. The results of the research showed that there was a relationship between knowledge, attitudes, eradicating mosquito nests, the color of the water reservoir, the location of the water reservoir, and the role of larva monitoring cadres (Jumantik) with the presence of Aedes aegypti mosquito larvae. It is hoped that the Payung Sekaki Community Health Center can provide KIE (Communication, Information, and Education) to the community regarding Dengue Hemorrhagic Fever (DHF), especially how to prevent the presence of Aedes aegypti mosquito larvae and the involvement of Jumantik Cadres is expected to be more active and effective.

The larvicidal efficacy and mechanism of action of 5-Ethenyl-2,2′-bithiophene extracted from Echinops ritro on Aedes aegypti larvae

Herein, we focused on the larvicidal effects and potential mechanisms of 5-ethenyl-2,2′-bithiophene (5 EB), a compound isolated from Echinops ritro L. on Aedes aegypti larvae. Our results show that 5 EB exhibits pronounced larvicidal activity against A. aegypti larvae, with an LC50 = 0.24 mg/L, considerably lesser than that of the traditional insecticide, rotenone. Observations using fluorescence microscopy, electron microscopy, and imaging flow cytometry demonstrated that 5 EB targets the hemocytes of larvae, leading to the disruption of their intracellular membrane systems. This disruption leads to considerable damage to the cellular structure and function, leading to the death of test subjects. Note that additional investigation into the molecular mechanism of 5 EB's action was conducted using transcriptomic analysis. Both GO and KEGG enrichment analyses reported that the differentially expressed genes were predominantly associated with membranes, lysosomes, and catalytic activities. To summarize, this study provides new options for developing new, environmentally friendly, plant-based larvicides for mosquito control.

"Symbiotic secrets: exploring the gut microbiome of Aedes aegypti larvae and its role in mosquito physiology"

"Symbiotic secrets: exploring the gut microbiome of Aedes aegypti larvae and its role in mosquito physiology"

Biocidal efficacy of olefinic N-alkylamides against Aedes aegypti and Culex quinquefasciatus larvae

Mosquito-borne diseases are a major public-health concern worldwide. The development of resistance in mosquitoes to the existing larvicides and the associated-risks necessitates the exploration of novel molecules to control vector-borne pathogens. This study demonstrates that N-alkylamides [2E,4E-N-isobutyl-undeca-2,4-diene-8,10-diynamide (1) and 2E,4E,8Z,10E-N-isobutyl-dodeca-2,4,8,10-tetraenamide (2)] of Acmella ciliata exhibit biocidal action against Aedes aegypti and Culex quinquefasciatus larvae. The LC50 for 1 and 2 were 44.19 and 18.28 ppm against Aedes larvae, and 30.89 and 11.75 ppm against Culex larvae, respectively. We further observed that the chain length, degree of unsaturation, and terminal methylation influence the larvicidal efficacy of N-alkylamides. HPLC-assisted quantification revealed that the content of both 1 (19.01 mg/g) and 2 (68.55 mg/g) was maximum in the flowers of A. ciliata. Thus, this study concludes that N-alkylamides are promising alternatives to control mosquito larvae and can be used as standard for quantitation in test samples.

A taste of a toxin paradise: Xenorhabdus and Photorhabdus bacterial secondary metabolites against Aedes aegypti larvae and eggs

Aedes-transmitted arboviral infections such as Dengue, Yellow Fever, Zika and Chikungunya are increasing public health problems. Xenorhabdus and Photorhabdus bacteria are promising sources of effective compounds with important biological activities. This study investigated the effects of cell-free supernatants of X. szentirmaii, X. cabanillasii and P. kayaii against Ae. aegypti eggs and larvae and identified the bioactive larvicidal compound in X. szentirmaii using The EasyPACId method. Among the three tested bacterial species, X. cabanillasii exhibited the highest (96%) egg hatching inhibition and larvicidal activity (100% mortality), whereas P. kayaii was the least effective species in our study. EasyPACId method revealed that bioactive larvicidal compound in the bacterial supernatant was fabclavine. Fabclavines obtained from promoter exchange mutants of different bacterial species such as X. cabanillasii, X. budapestensis, X. indica, X. szentirmaii, X. hominckii and X. stockiae were effective against mosquito larvae. Results show that these bacterial metabolites have potential to be used in integrated pest management (IPM) programmes of mosquitoes.

Exposure to low-concentration fipronil impairs survival, behavior, midgut morphology and physiology of Aedes aegypti larvae

The Aedes aegypti mosquito is a vector for various arboviruses, including dengue and yellow fever. Insecticides, such as pyrethroids and organophosphates, are widely used to manage and control these insects. However, mosquitoes have developed resistance to these chemicals. Therefore, this study aimed to investigate the effects of the commercial formulation of fipronil (Tuit® Florestal; 80% purity) on the survival, behavior, morphology, and proteins related to signaling pathways of the midgut in A. aegypti larvae under controlled laboratory conditions. Significant reductions in immature survival were observed in all concentrations of fipronil tested. Low insecticide concentration (0.5 ppb) led to decreased locomotor activity in the larvae and caused disorganization of the epithelial tissue in the midgut. Moreover, exposure to the insecticide decreased the activity of detoxifying enzymes such as catalase, superoxide dismutase, and glutathione-S-transferase. On the other hand, the insecticide increased protein oxidation and nitric oxide levels. The detection of LC3, caspase-3, and JNK proteins, related to autophagy and apoptosis, increased after exposure. However, there was a decrease in the positive cells for ERK 1/2. Furthermore, the treatment with fipronil decreased the number of positive cells for the proteins FMRF, Prospero, PH3, Wg, Armadillo, Notch, and Delta, which are related to cell proliferation and differentiation. These findings demonstrate that even at low concentrations, fipronil exerts larvicidal effects on A. aegypti by affecting behavior and enzymatic detoxification, inducing protein oxidation, free radical generation, midgut damage and cell death, and inhibiting cell proliferation and differentiation. Thus, this insecticide may represent a viable alternative for controlling the spread of this vector.

Exploiting the combination of entomopathogenic fungi and Illicium verum essential oil against Aedes aegypti larvae

Here, the effectiveness of Beauveria bassiana LCM S19 and Metarhizium anisopliae LCM S01, combined with Illicium verum essential oil (EO) against Aedes aegypti larvae was investigated. The EO compounds were first identified through gas chromatography, with the primary compound being (E)-anethole. Subsequently, in silico analysis was employed to predict the biological activity of (E)-anethole, revealing 89 molecular targets, which included insecticidal activity. Next the impact of EO on fungal viability and colony growth was examined and the EO had no effect on fungal development. Next, we investigated the influence of EO on fungal viability and colony growth, revealing that the EO had no discernible impact on fungal development. Following this, individual assessments were carried out to determine larval susceptibility to EO at concentrations of 40, 60, 80, and 100 ppm, as well as with both fungal isolates at conidial concentrations of 1 × 106, 1 × 107, and 1 × 108 conidia/mL. Larval survival was then monitored over a period of seven days. To further optimize the larvicidal potential, EO at a concentration of 40 ppm was combined with both isolates at a conidial concentration of 1 × 106 conidia/mL and tested against mosquito larvae, as described earlier. The combination of M. anisopliae and EO resulted in a substantial decrease, with only 20 % of larvae surviving over a seven-day period, in contrast to approximately 50 % survival observed in the pure M. anisopliae or EO treatments. B. bassiana, whether used alone or in combination with EO, exhibited a 50 % reduction in larval survival. The combination of M. anisopliae and EO exhibited a synergistic effect in targeting Ae. aegypti larvae, whereas B. bassiana, in conjunction with EO, had an additive effect. Notably, the combination achieved its impact in just 3 days, whereas the pure fungus required 7 days to yield similar results. These findings underscore the substantial potential of combining I. verum essential oil with both fungal isolates against Ae. aegypti larvae.

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.

Bioactive components in Psidium guajava extracts elicit biotoxic attributes and distinct antioxidant enzyme modulation in the larvae of vectors of lymphatic filariasis and dengue

Control of mosquito vectors, which have caused a global disease burden, has employed various methods. However, the challenges posed by current physical and chemical methods have raised concerns about vector control programs, leading to the search for alternative methods that are less toxic, eco-friendly, and cost-effective. This study investigated the larvicidal potential of aqueous, methanol, and ethylacetate extracts of Guava (Psidium guajava) against Aedes aegypti and Culex quinquefasciatus larvae. Functional group and phytochemical characterization were performed using Fourier-Transform Infrared Spectroscopy (FTIR) and GC-MS analysis to identify the bioactive compounds in the extracts. Larval bioassays were conducted using WHO standard procedures at concentrations of 12.5, 25, 50, 125, and 250 mg/L, and mortality was recorded after 24, 48, and 72 h. Additionally, antioxidant enzyme profiles in the larvae were studied. All of the solvent extracts showed larvicidal activity, with the methanol extract exhibiting the highest mortality against Ae. aegypti and Cx. quinquefasciatus larvae, followed by aqueous and ethylacetate extracts. FTIR spectroscopic analysis revealed the presence of OH, C–H of methyl and methylene, CO and CC. The GC-MS analysis indicated that the methanol, aqueous, and ethylacetate extracts all had 27, 34, and 43 phytoactive compounds that were effective at causing larvicidal effects, respectively. Different concentrations of each extract significantly modulated the levels of superoxide dismutase, catalase, glutathione peroxidase, and reduced glutathione in larvae. This study's findings indicate the potential for developing environmentally friendly vector control products using the bioactive components of extracts from P. guajava leaves.

Ammonia transport in the excretory system of mosquito larvae (Aedes aegypti): Rh protein expression and the transcriptome of the rectum

The role of the mosquito excretory organs (Malpighian tubules, MT and hindgut, HG) in ammonia transport as well as expression and function of the Rhesus (Rh protein) ammonia transporters within these organs was examined in Aedes aegypti larvae and adult females. Immunohistological examination revealed that the Rh proteins are co-localized with V-type H+-ATPase (VA) to the apical membranes of MT and HG epithelia of both larvae and adult females. Of the two Rh transporter genes present in A. aegypti, AeRh50-1 and AeRh50-2, we show using quantitative real-time PCR (qPCR) and an RNA in-situ hybridization (ISH) assay that AeRh50-1 is the predominant Rh protein expressed in the excretory organs of larvae and adult females. Further assessment of AeRh50-1 function in larvae and adults using RNAi (i.e. dsRNA-mediated knockdown) revealed significantly decreased [NH4+] (mmoll-1) levels in the secreted fluid of larval MT which does not affect overall NH4+ transport rates, as well as significantly decreased NH4+ flux rates across the HG (haemolymph to lumen) of adult females. We also used RNA sequencing to identify the expression of ion transporters and enzymes within the rectum of larvae, of which limited information currently exists for this important osmoregulatory organ. Of the ammonia transporters in A. aegypti, AeRh50-1 transcript is most abundant in the rectum thus validating our immunohistochemical and RNA ISH findings. In addition to enriched VA transcript (subunits A and d1) in the rectum, we also identified high Na+-K+-ATPase transcript (α subunit) expression which becomes significantly elevated in response to HEA, and we also found enriched carbonic anhydrase 9, inwardly rectifying K+ channel Kir2a, and Na+-coupled cation-chloride (Cl-) co-transporter CCC2 transcripts. Finally, the modulation in excretory organ function and/or Rh protein expression was examined in relation to high ammonia challenge, specifically high environmental ammonia (HEA) rearing of larvae. NH4+ flux measurements using the scanning-ion selective electrode (SIET) technique revealed no significant differences in NH4+ transport across organs comprising the alimentary canal of larvae reared in HEA vs freshwater. Further, significantly increased VA activity, but not NKA, was observed in the MT of HEA-reared larvae. Relatively high Rh protein immunostaining persists within the hindgut epithelium, as well as the ovary, of females at 24-48h post blood meal corresponding with previously demonstrated peak levels of ammonia formation. These data provide new insight into the role of the excretory organs in ammonia transport physiology and the contribution of Rh proteins in mediating ammonia movement across the epithelia of the MT and HG, and the first comprehensive examination of ion transporter and channel expression in the mosquito rectum.

Roles of a newly lethal cuticular structural protein, AaCPR100A, and its upstream interaction protein, G12-like, in Aedes aegypti

Mosquitoes form a vital group of vector insects, which can transmit various diseases and filarial worms. The cuticle is a critical structure that protects mosquitoes from adverse environmental conditions and penetration resistance. Thus, cuticle proteins can be used as potential targets for controlling the mosquito population. In the present study, we found that AaCPR100A is a structural protein in the soft cuticle, which has flexibility and elasticity allowing insects to move or fly freely, of Aedes aegypti. RNA interference (RNAi) of AaCPR100A caused high mortality in Aedes aegypti larvae and adults and significantly decreased the egg hatching rate. Transmission electron microscopy (TEM) analysis revealed that the larval microstructure had no recognizable endocuticle in AaCPR100A-deficient mosquitoes. A yeast two-hybrid assay was performed to screen proteins interacting with AaCPR100A. We verified that the G12-like protein had the strongest interaction with AaCPR100A using yeast two-hybrid and GST pull-down assays. Knockdown of G12-like transcription resulted in high mortality in Ae. aegypti larvae, but not in adults. Interestingly, RNAi of G12-like rescued the high mortality of adults caused by decreased AaCPR100A expression. Additionally, adults treated with G12-like dsRNA were found to be sensitive to low temperature, and their eggshell formation and hatching were decreased. Overall, our results demonstrated that G12-like may interacts with AaCPR100A, and both G12-like and AaCPR100A are involved in Ae. aegypti cuticle development and eggshell formation. AaCPR100A and G12-like can thus be considered newly potential targets for controlling the Ae. aegypti mosquito.

Characterization of the fragmentation mechanisms in electrospray ionization tandem mass spectrometry of chloroquinoline derivatives with larvicidal activity against Aedes aegypti.

4,7-Dichloroquinoline (DCQ) represents a group of synthetic molecules inspired by natural products with important roles in biological and biomedical areas. This work aimed to characterize DCQ and its derivatives by high-resolution electrospray ionization (ESI) mass spectrometry and tandem mass spectrometry (ESI-MS/MS), supported by theoretical calculations. Biological assays were carried out with DCQ and its derivatives to determine LC50 values against Aedes aegypti larvae. Five DCQ derivatives were synthesized by using previously described protocols. ESI-MS/MS analyses were carried out with a quadrupole/time-of-flight and ion-trap instrument. The proposed gas-phase protonation sites and fragmentation were supported by density functional theory calculations. The larvicidal tests were performed with the Ae. aegypti Rockefeller strain, and the LC50 values were determined by employing five test concentrations. Larval mortality was determined after treatment for 48 h. DCQ bromides or aldehydes (C-3 or C-8 positions), as well as the trimethylsilyl derivative (C-3 position), were prepared. Detailed ESI-MS/MS data revealed heteroatom elimination through an exception to the even-electron rule, to originate open-shell species. Computational studies were used to define the protonation sites and fragmentation pathways. High activity of DCQ and its derivatives against Ae. aegypti larvae was demonstrated. Our results provided a well-founded characterization of the fragmentation reactions of DCQ and its derivatives, which can be useful for complementary studies of the development of a larvicidal product against Ae. aegypti.

Limonoids from the fruits of Chisocheton erythrocarpus and their mosquito larvicidal activities

Phytochemical study of the fruits of Chisocheton erythrocarpus (Hiern) allowed the identification of eight undescribed limonoids, namely erythrocarpines O – V (1–6, 7a and 7b), along with seven known compounds. The structures of these compounds were elucidated based on spectroscopic and HRMS data, along with electronic circular dichroism to configure the absolute configuration. Erythrocarpines O and P are γ-hydroxybutenolide analogs of mexicanolide-type limonoids while erythrocarpine Q – V are phragmalin-type limonoids possessing a 1,29-oxymethylene bridge with either benzoyl or cinnamoyl moiety in their structures. Mosquito larvicidal activity revealed that crude DCM extract of C. erythrocarpus possessed a good larvicidal effect against Aedes aegypti larvae in 48 h (LC50 = 153.0 ppm). Subsequent larvicidal activity of isolated compounds indicated that erythrocarpine G (10) and 14-deoxyxyloccensin K (11) were responsible for the enhanced larvicidal effect of the extract, reporting LC50 values of 18.55 ppm and 41.16 ppm, respectively. Moreover, residual activity testing of the crude DCM extract revealed that the duration of its larvicidal effects is up to 14 days, where it maintained a 98 % larval mortality throughout the test period, under laboratory conditions.

Effectiveness of Foeniculum vulgare leaf essential oil nanoemulsion as a natural insecticide against Aedes aegypti larvae and mosquitoes

Abstract. Wardani AT, Kusumaningsih T, Ainurofiq A. 2024. Effectiveness of Foeniculum vulgare leaf essential oil nanoemulsion as a natural insecticide against Aedes aegypti larvae and mosquitoes. Biodiversitas 25: 990-997. The control of dengue hemorrhagic fever (DHF) was by breaking the chain of transmission by controlling Aedes aegypti larvae and mosquitoes. One alternative to controlling mosquito larvae is to use natural materials because they are more environmentally friendly and do not cause harmful residual effects. This study used a Foeniculum vulgare Mill. (fennel) leaf as a natural insecticide to kill Ae. aegypti larvae and mosquitoes. Steam distillation was done to extract essential oils from the Foeniculum vulgare Mill. leaves. F. vulgare leaf essential oil was made as nanoemulsion with tween 80, PEG 400, essential oil, and aqua demineralized. GC-MS results showed that the main ingredients in F. vulgare. leaf essential oil were anethole, estragole, bicyclo[3.1.0]hex-2-ene, 4-methyl-1-(1-methyl ethyl)-,?-pinene, cyclohexene, 1-methyl-5-(1-methyl ethenyl)-, (R)-.The current study aimed to determine the effectiveness of an F. vulgare essential oil nanoemulsion as a larvicidal, adulticidal Ae.aegypti mosquito. The study results obtained LC50 values for each formula I, II, and III were 0.098, 0.317, 0.157 µL/mL, and LC90 values for each formula I, II, and III were 0.158, 0.416, 0.245 µL/mL. Fennel leaf essential oil nanoemulsion was tested on adult Ae. aegypti mosquitoes aged 3-5 days. The results of the study obtained LC50 values for each formula I, II, III were 7.768, 10.575, 5.069 g/m3, and LC90 values for each formula I, II, III were 15.191, 27.565, 8.892 g/m3. The difference in the effectiveness of each formula may be due to the large number of essential oils in the formula. F. vulgare leaf essential oil could be an environmentally friendly natural insecticide with less residual effect.

Elytrigia Repens Extracts Control Urban Mosquito Vectors with a Larvicidal Potential

There is over 17% of global illnesses due to Vector-borne diseases and more than a million fatalities annually found as a significant public health challenge globally. Traditional methods of mosquito control are relied heavily on chemical insecticides, and led to ecological disruptions, pesticide resistance, and adverse effects on human health and the environment. Consequently, there is a persistent need for alternative and eco-friendly strategies mosquito control. Method: In this study, we investigated the efficacy of extracts from Eragrostis repens (E. repens) against the larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Plant extracts were prepared using different solvents, and their phytochemical profiles were analyzed. The larvicidal activity of these extracts was evaluated through susceptibility tests over a 24-hour period. Results: Methanol extracts exhibited significant larvicidal activity against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus, with LC50 values ranging from 43,173 ppm to 58,234 ppm. GC-MS analysis identified 11 bioactive compounds in methanol extracts, highlighting their potential insecticidal activity. Conclusion: Our findings suggest that E. repens holds promise as a natural larvicide against mosquito vectors. The study highlights the importance of exploring botanical alternatives for mosquito control, offering a sustainable and environmentally friendly approach to combatting mosquito-borne diseases.

Analysis of Aedes Aegypti Larval Density on The Potential Transmission of Dengue Fever

Dengue hemorrhagic fever (DHF) is caused by the dengue virus transmitted through the Aedes aegypti mosquito. DHF remains a health problem in Indonesia. Based on data from the Ministry of Health, there were 184 cases of the disease in 2022, an increase of 94.8% compared to 2021, which had 73,518 cases. According to the Central Statistics Agency of South Sumatra Province, the number of DHF cases in South Sumatra was 2,854 cases, with the highest number in the city of Palembang at 908 cases. This condition requires serious attention. The aim of this study is to analyze the potential transmission of DHF based on entomological evidence in the Sukarami district of Palembang. The method used in the research is a cross-sectional study conducted in December 2023, involving 92 households in the Sukarami sub-district, with a total of 552 containers. The survey results of larval identification under a microscope showed a Larval Free Index of 45.7%, a Container Index of Aedes aegypti larvae of 56.0%, a house index of 73.9%, and a Breteau index of 152.2%. The results of entomological indices indicate a high density of DHF vector mosquitoes Aedes aegypti, which means that this area has a high risk of DHF transmission, thus requiring the control of Aedes aegypti larvae and the eradication of DHF. breeding sites for the vector.

GC/GC-MS analysis and biological activities of Lantana Camara Linn.

Medicinal plants have been a part of human history for thousands of years and are still used as healthcare throughout the world. The current research aims to explore the chemical constituents of the methanol soluble extract (LC-Me) and petroleum ether soluble fraction (LCM-PES) from the leaves of Lantana camara Linn by GC/ GC-MS. This chemical analysis revealed the existence of 16 and 23 phytoconstituents in LC-Me and LCM-PES respectively. The major constituents in LC-Me were found to beethyl 9,12,15-octadecatrienoate (31.9%), hexadecanoic acid, ethyl ester (12.6%), n-hexadecanoic acid (11.1%), linoleic acid ethyl ester (9.1%), squalene (8.7%), di-n-octyl phthalate (6.2%), 9,12-octadecadienoic acid (Z,Z)- (4.2%), (E)-9-octadecenoic acid ethyl ester (2.7%) andcyclopropanebutanoicacid,2-[[2-[[2-[(2-pentylcyclopropyl)methyl]cyclopropyl]methyl]cyclopropyl]methyl]-, methyl ester (2.3%). The chief bioactive compounds in petroleum ether soluble fraction were found to beandrost-8-en-3-ol, 4,4,14α-trimethyl-17-(2-bromo-1-methylethyl (57.9%), 14,17-nor-3,21-dioxo-β-amyrin, 17,18-didehydro-3-dehydroxy- (13.0%), barringtogenol B (2.5%), olean-12-ene-3,16,21,22,28-pentol, 21-(2-methyl-2-butenoate), [3β,16α,21β(Z),22α]-(1.7%),perhydrocyclopropa[e]azulene-4,5,6-triol, 1,1,4,6-tetramethyl (1.7%), ethyl iso-allocholate (1.6%) and 1,2-benzenedicarboxylic acid, diisooctyl ester (1.6%). Both the extract and its fraction have exhibited very significant antibacterial, antifungal,mosquito repellent and larvicidal propertiesoriginated by numerous bioactive metabolites. Twenty eight (20 Gram-positive and 8 Gram-negative) bacteria were tested against LC.Me and LCM-PESwith noteworthy zone of inhibition.The significant in vitro antifungal activity was observed against fifteen fungi in LC-Me and LCM-PES. Very robust initial repellency was observed for LC-Me and LCM-PES (94% and 80% respectively) against the dengue-carrying mosquito (Aedes aegypti) at 2% concentration. The extract and its fraction were also found to be an efficient larvicidal agent against fourth-stage larvae of Aedes aegypti. The effective larvicidal property was noted in methanol soluble extract as compared topetroleum ether soluble fraction and standard with LC50value of 20 and 400 ppm respectively.

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.

Photoactivated 9-methylacridine destroys midgut tissues of Aedes aegypti larvae by targeting ROS-mediated apoptosis in the mitochondrial pathway of midgut cells

An aromatic ring-containing compound with a wide range of biological activities, 9-methylacridine (AD-9-Me) is a precursor for the synthesis of various drugs. However, its photoactivation properties and mechanism of damage as a photo activator against Aedes aegypti are unknown. The toxic effects of AD-9-Me on Aedes aegypti mosquitoes were determined under light and non-light conditions. The results showed that the toxicity of AD-9-Me to mosquito larvae was significantly higher than that of the dark treatment after 24 h of light exposure; AD-9-Me was mainly distributed in the midgut of larvae, after 24 h of treatment, it can cause an increase in calcium ion concentration, reactive oxygen species (ROS) eruption and ROS accumulation by blocking the ROS elimination pathway in midgut cells. This in turn caused an increase in protein carbonyl and malondialdehyde (MDA) content, a decrease in mitochondrial membrane potential (MMP), a disruption of the barrier function of midgut tissues, a significant decrease in midgut weight and chitin content, which induced the up-regulation of AeDronc, AeCaspase8 and AeCaspase7 genes, leading to apoptotic cell death. In this study, we confirmed that AD-9-Me has photoactivation activity and mainly acts on the midgut of mosquito larvae, which can generate a large amount of ROS in the cells of the midgut and induce apoptosis to occur, resulting in the disruption of the function of the tissues of mosquito larvae, accelerating the death and delaying the development of the mosquito larvae.

The Biocidal capacity of Datura (Datura stramonium L.) leaves and flowers and Cannabis (Cannabis sativa L.) seeds on some Mosquito’s larvae (Diptera: Culicidae)

Plant-based alternative pesticides are safe, effective, eco-friendly and can be used instead of synthetic pesticides. The aim of this study was to evaluate the biocidal capacity of Datura stramonium leaves (DL) and flowers (DF) and Cannabis sativa seeds (CS) on Anopheles arabiensis, Culex quiquefasciatus and Aedes aegypti larvae. The selected plant parts were collected from the experimental farm, the University garden. The LC50s of A. arabinoses larvae towards the ethanol extract of each plant part were taken to estimate the single diagnostic dose for the survival and deformities tests. GC-MS analysis for the selected plant parts was investigated. The results show that DL ethanol extract detected 14 compounds of which butanol,3-methyl is the main component (79.76%) followed by toluene (6.14%). Phytol was also detected (3.9%). 14 compounds were detected from DF of which formic acid,3-methylbut-2-yl ester was the main component (82.22%) followed by dodecanoic acid, ethyl ester (3.3%) and toluene (2.86%). Also, from CS, Dronabinol (41.4%) was the main component, followed by Cannabinol (10.38%), Phytol (10.38%) and Caryophylene (2.07%). The susceptibility test of An. arabiensis larvae revealed the LC50’s of 562.95 mg/L for DL, 424.41 mg/L for DF and 175.40 mg/L for CS. It was noticed that 3-6% of An. arabiensis and 1-28% of Culex quiquefasciatus and 12-22% of Aedes aegypti larvae developed to pupae and some of them developed to adult stage after one week. In the survival test, more than 70% of the larvae were killed by a concentration supposed to kill 50% or less of the larvae. Some deformations were monitored on Anopheles, Culex and Aedes larvae including swelled body, separated alimentary canal. Field assessment should be run and the concept of LC50 should be re-written.