Larvicidal potential of plant-based extracts against dengue vector: A short review.

INTRODUCTION: Dengue fever, a vector borne disease transmitted primarily by Aedes albopictus and Aedes aegypti mosquitoes, has triggered a significant global resurgence. While many vector control programs depend on the use of chemical insecticides to curb outbreaks, its heavy reliance raises environmental concerns and the risk of insecticide resistance. Alternatively, botanically derived insecticidal agents with larvicidal properties offer an ecofriendlier option. This review aims to analyze scientific reports that described the effectiveness of plant-derived extracts for vector control. MATERIALS AND METHODS: A literature search was performed to analyze studies that focused on plant-based extracts used for larvicidal purposes using databases such as Science Direct. Springer, PubMed, and Scopus. The inclusion criteria for publications were larvicidal effects, published in English from the year 2017 and availability of full-text articles. The available literature was further characterized by the value of larvicidal activities of LC50 and LC90 (< 50 ppm), of 22 different parts of plant species from 7 plant families namely Apiaceae, Asteraceae, Lauraceae, Magnoliaceae, Myrtaceae, Piperaceae and Rubiaceae. RESULTS: When comparing the values of LC50, 12 plants species (Artemisia vulgaris, Crassocephalum crepidioides, Echinops grijsii, Melaleuca leucadendra, Neolitsea ellipsoidea, Pavetta tomentosa, Piper betle, Piper caninum, Piper Montium, Piper muntabile, Piper ovatum, Tarenna asiatica) showed promising larvicidal efficacies with LC50 < 10 ppm. CONCLUSION: This review emphasizes the effective alternatives of plant extracts for the potential production of larvicides. Piper betle extract and chloroform extract of Tarenna asiatica reported the most significant larvicidal activity (LC50 < 1 ppm) against mosquito vectors. Further reviews focusing on the mode of actions of its phytochemically constituents are essential for the future development of potentially significant plant-based larvicides.

Anti-dengue potential and mosquitocidal effect of marine green algae-stabilized Mn-doped superparamagnetic iron oxide nanoparticles (Mn-SPIONs): an eco-friendly approach.

Vector-borne diseases pose a significant public health challenge in economically disadvantaged nations. Malaria, dengue fever, chikungunya, Zika, yellow fever, Japanese encephalitis, and lymphatic filariasis are spread by mosquitoes. Consequently, the most effective method of preventing these diseases is to eliminate the mosquito population. Historically, the majority of control programs have depended on chemical pesticides, including organochlorines, organophosphates, carbamates, and pyrethroids. Synthetic insecticides used to eradicate pests have the potential to contaminate groundwater, surface water, beneficial soil organisms, and non-target species. Nanotechnology is an innovative technology that has the potential to be used in insect control with great precision. The goal of this study was to test the in vitro anti-dengue potential and mosquitocidal activity of Chaetomorpha aerea and C. aerea-synthesized Mn-doped superparamagnetic iron oxide nanoparticles (CA-Mn-SPIONs). The synthesis of CA-Mn-SPIONs using C. aerea extract was verified by the observable alteration in the colour of the reaction mixture, transitioning from a pale green colour to a brown. The study of UV-Vis spectra revealed absorbance peaks at approximately 290 nm, which can be attributed to the surface Plasmon resonance of the CA-Mn-SPIONs. The SEM, TEM, EDX, FTIR, vibrating sample magnetometry, and XRD analyses provided evidence that confirmed the presence of CA-Mn-SPIONs. In the present study, results revealed that C. aerea aqueous extract LC50 values against Ae. aegypti ranged from 222.942 (first instar larvae) to 349.877 ppm in bioassays (pupae). CA-Mn-SPIONs had LC50 ranging from 20.199 (first instar larvae) to 26.918 ppm (pupae). After treatment with 40 ppm CA-Mn-SPIONs and 500 ppm C. aerea extract in ovicidal tests, egg hatchability was lowered by 100%. Oviposition deterrence experiments showed that in Ae. aegypti, oviposition rates were lowered by more than 66% by 100 ppm of green algal extract and by more than 71% by 10 ppm of CA-Mn-SPIONs (oviposition activity index values were 0.50 and 0.55, respectively). Moreover, in vitro anti-dengue activity of CA-Mn-SPIONs has good anti-viral property against dengue viral cell lines. In addition, GC-MS analysis showed that 21 intriguing chemicals were discovered. Two significant phytoconstituents in the methanol extract of C. aerea include butanoic acid and palmitic acid. These two substances were examined using an in silico methodology against the NS5 methyltransferase protein and demonstrated good glide scores and binding affinities. Finally, we looked into the morphological damage and fluorescent emission of third instar Ae. aegypti larvae treated with CA-Mn-SPIONs. Fluorescent emission is consistent with ROS formation of CA-Mn-SPIONs against Ae. aegypti larvae. The present study determines that the key variables for the successful development of new insecticidal agents are rooted in the eco-compatibility and the provision of alternative tool for the pesticide manufacturing sector.

Effectiveness of Eupatorium perfoliatum 30C in Prevention of Dengue Fever and Acute Febrile Illness during 2017 Dengue Outbreak in Urban Slums of Delhi: A Prospective, Open-Label, Community-Based, Parallel Cohort Study.

OBJECTIVE: This study was undertaken to assess the effectiveness of Eupatorium perfoliatum (EP) 30C on the incidence of dengue fever and acute febrile illness (AFI) during the 2017 dengue outbreak. METHODS: We conducted a prospective, open-label, community-based parallel cohort study involving apparently healthy individuals residing in 06 urban slums (JJ colony) of Delhi. The participants were enrolled in two cohorts - the medicine cohort (MC) and the control cohort (CC). Participants in MC were given weekly one dose of EP 30C for 10 weeks along with Information, Education and Communication (IEC) material regarding dengue. Participants in the CC were provided with the IEC material only. The primary outcome measure was the incidence of dengue fever as per case definitions notified in the national guidelines for clinical management of dengue fever by the Government of India during the 10 weeks follow-up period. The secondary outcome measures were the incidence of AFI and the hospitalization of confirmed dengue cases. RESULTS: The analysis included 40,769 participants residing in 06 slum clusters of Delhi out of which 28,321 participants were in MC and 12,448 participants were in CC. The incidence of laboratory-confirmed dengue in the MC was 2.57 per 10,000 person-weeks (95% confidence interval [CI], 2.02-3.22) in comparison with 7.55 per 10,000 person-weeks (95% CI, 6.12-9.21) in the CC. The incidence of AFI in the MC was 19.66 per 10,000 person-weeks (95% CI, 18.07-21.36) in comparison with 40.96 per 10,000 person-weeks (95% CI, 37.48-44.67) in the CC. The overall protective effect of EP against laboratory-confirmed dengue was 65.77% (95% CI, 53.37-74.87; p = 0.0001) and against AFI was 52.58% (95% CI, 46.37-58.07; p = 0.0001). Hospitalization reported in the MC was nil as against 4.35% in the CC. No dengue-related case fatalities were reported from either cohort. None of the participants from the MC reported any adverse events owing to the prophylactic intervention. CONCLUSION: The study concludes that EP 30C was able to prevent dengue significantly. Randomized controlled trials are needed to confirm or refute our findings.Das Ziel dieser Studie war die Beurteilung der Wirksamkeit von Eupatorium perfoliatum (EP) 30C auf die Inzidenz von Dengue-Fieber und akuter fiebriger Erkrankung (AFE) während des Dengue-Ausbruchs 2017.Wir führten eine prospektive, unverblindete, Bevölkerungs-Parallelgruppen-Kohortenstudie mit augenscheinlich gesunden Bewohnern von 6 städtischen Slums (JJ-Kolonie) in Delhi durch. Die Teilnehmer wurden in 2 Kohorten aufgenommen, einer Medizinkohorte (MK) und einer Kontrollkohorte (KK). Die Teilnehmer in der MK erhielten 10 Wochen lang wöchentlich eine Dosis EP 30C und dazu Aufklärungsmaterialien über Dengue. Die Teilnehmer in der KK erhielten nur die Aufklärungsmaterialien. Die primäre Zielgröße war die Dengue-Fieber-Inzidenz laut der in den nationalen Leitlinien für das klinische Management des Dengue-Fiebers von der indischen Regierung bekannt gegebenen Falldefinition in dem zehnwöchigen Beobachtungszeitraum. Die sekundären Zielgrößen waren die Inzidenz von AFE und die Anzahl hospitalisierter bestätigter Dengue-Fälle.In die Analyse wurden 40,769 Bewohner von 6 Slum-Clustern in Delhi einbezogen, davon wurden 28,321 Teilnehmer in die MK aufgenommen und 12,448 Teilnehmer in die KK. Die Inzidenz von im Labor bestätigter Dengue betrug in der MK 2,57 pro 10,000 Personen/Woche (95%-Konfidenzintervall [KI]: 2,02­3,22), verglichen mit 7,55 pro 10,000 Personen/Woche (95%-KI: 6,12­9,21) in der KK. Die Inzidenz von AFI betrug in der MK 19,66 pro 10,000 Personen/Woche (95%-Konfidenzintervall [KI]: 18,07­21,36), verglichen mit 40,96 pro 10,000 Personen/Woche (95%-KI: 37,48­44,67) in der KK. Der Schutzeffekt (SE) von EP betrug gegen im Labor bestätigte Dengue 65,77% (95%-KI: 53,37­74,87; p = 0,0001) und gegen AFI 52,58% (95%-KI: 46,37­58,07; p = 0,0001). Die Hospitalisierungsrate war in der MK gleich Null versus 4,35% in der KK. In keiner Kohorte waren Dengue-bedingte Todesfälle zu verzeichnen. Bei keinem der Teilnehmer in der MK traten jegliche unerwünschten Ereignisse infolge der prophylaktischen Maßnahme auf.Die Studie gelangt zu dem Schluss, dass Eupatorium perfoliatum 30C in signifikantem Maße Dengue vorbeugen konnte. Randomisierte kontrollierte Studien sind erforderlich, um unsere Ergebnisse zu bestätigen bzw. zu widerlegen.

Octadecadienoate derivatives from Michelia champaca seed extract as potential larvicide and pupicide against Dengue vector Aedes albopictus.

The present study was designed aiming at finding novel botanicals for controlling the vector population. Objective was to evaluate the larvicidal and pupicidal efficacies of crude and solvent extracts of Michelia champaca seed against the notorious dengue vector Aedes albopictus. 0.5% concentration of the crude extractive and 40 ppm concentration of ethyl acetate extractive were enough to execute 100% of larval mortality of all the instars after 72 h of exposure and the LC50 and LC90values (95% confidence level) of ethyl acetate extractive were 0.9880 ppm and 36.0491 ppm. In case of pupicidal bioassay, 100% mortality was observed at 200 ppm of ethyl acetate extract. Through TLC techniques, the bioactive compounds were isolated, which caused remarkable larval toxicity at 15 ppm concentration. Three-way factorial ANOVA analysis showed different concentrations, time intervals, and instars revealed a significant difference in larval death. FT-IR analysis revealed the presence several important functional groups. Presence of methyl 5,12-octadecadienoate and ethyl 9cis,11trans-octadecadienoate were ascertained by GC-MS analysis. The said bioactive compounds showed very low toxicity in non-target organisms such as damselfly (Ischnura sp.) and water bug (Diplonychus sp.) Thus, proclaiming the potentialities of Michelia champaca seed extracts as larvicidal and pupicidal agents against Ae. albopictus.

Discovery and structure-activity relationship of Morita-Baylis-Hillman adducts as larvicides against dengue mosquito vector, Aedes aegypti (Diptera: Culicidae).

Neglected tropical diseases (NTDs) have become a significant public health problem worldwide, notably the life-threatening dengue hemorrhagic fever borne by the Aedes aegypti mosquito. Thus, mosquito vector control measures remain essential in public health vector surveillance and control to combat Aedes-borne infections. Therefore, a series of MBH adducts were synthesized and assessed towards the fourth instar mosquito larvae, Aedes aegypti, along with the preliminary structure-activity relationship (SAR). Noteworthy, this compound class might be synthetized by an efficient eco-friendly synthesismethod and a rapid route for the synthesis of commercial larvicide through a single synthetic step. The bioassays showed that this compound class is a promising larvicide to control Aedes aegypti mosquito larvae, mainly 3g, with an LC50 of 41.35 µg/mL, which was higher than evaluated positive controls. Nevertheless, it is a viable larvicidalhit candidate for further hit-to-leadproperties optimization of its biphenyl backbone scaffold with enhanced insecticidalbioactivity. Moreover, scanning electron microscopy analysis suggested a disruption of the osmoregulatory/ionoregulatory functions by the complete deterioration of the terminal exoskeleton hindgut and anal papillae. Therefore, this new study shows the larvicidal efficacy of the tested compounds against the Aedes aegypti larvae.

Chemical constituents and strong larvicidal activity of Solanum xanthocarpum among selected plants extracts against the malaria, filaria, and dengue vectors.

BACKGROUND & OBJECTIVES: The role of mosquitoes is instrumental in the transmission of various diseases. Mosquitoe-borne diseases account for a significant share of the global burden of total infectious diseases. Vector control is the principal method for the control of these mosquito-borne diseases. Plant-derived insecticides serve as an effective alternative to chemical insecticides. The present study has been undertaken to assess the larvicidal potential of methanol and petroleum ether extracts of leaves of Solanum xanthocarpum, Parthenium hysterophorus, Manihot esculenta, and Chamaecyparis obtusa. METHODS: Larvicidal activity was tested against the early four-stage instar larvae of laboratory-reared susceptible strains of the malaria vector, Anopheles stephensi, dengue fever vector, Aedes aegypti, and the lymphatic filariasis vector, Culex quinquefasciatus at 20 to 120 ppm concentrations. Further, liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectroscopy (GC-MS) analyses were carried out to identify the bioactive compounds present in the methanolic leaf extracts of Solanum xanthocarpum for designing a larvicidal product in future. RESULTS: After 72 h of exposure high larvicidal activities were observed in methanolic and petroleum ether leaves extract of S. xanthocarpum against An. stephensi, Ae. aegypti and Cx. quinquefasciatus. The larvicidal activities for methanol and petroleum ether leaf extract of S. xanthocarpum with LC50 = 09.201 and 12.435 ppm and LC90 = 21.578 and 27.418 ppm for An. stephensi; LC50 = 11.450 and 10.026 ppm and LC90 = 26.328 and 22.632 ppm for Ae. aegypti and LC50 = 12.962 and 13.325 ppm and LC90 = 26.731 and 30.409 ppm for Cx. quinquefasciatus, respectively, were found to be most effective. GC-MS analysis revealed 43 compounds, amongst these phytol (13.09%), 3-allyl-2-methoxy phenol (9.55%), (9Z, 12Z)-9, 12-octadecadienoyl chloride (7.93%), linoleic acid (5.45%), alpha-tocospiro B (5.08%) and hexadecanoic acid (4.35%) were identified as major compounds. INTERPRETATION & CONCLUSION: Present work showed that leaf extracts of S. xanthocarpum are a source of potential natural candidate that possess several phytochemicals which can be explored further for the development of ecologically safer mosquito control products.

Sonication and heat-mediated synthesis, characterization and larvicidal activity of sericin-based silver nanoparticles against dengue vector (Aedes aegypti).

Fabrication, characterization and evaluation of the larvicidal potential of novel silk protein (sericin)-based silver nanoparticles (Se-AgNPs) were the prime motives of the designed study. Furthermore, investigation of the sericin as natural reducing or stabilizing agent was another objective behind this study. Se-AgNPs were synthesized using sonication and heat. Fabricated Se-AgNPs were characterized using particle size analyzer, UV spectrophotometry, FTIR and SEM which confirmed the fabrication of the Se-AgNPs. Size of sonication-mediated Se-AgNPs was smaller (7.49 nm) than heat-assisted Se-AgNPs (53.6 nm). Being smallest in size, sonication-assisted Se-AgNPs revealed the significantly highest (F4,10 = 39.20, p = .00) larvicidal activity against fourth instar lab and field larvae (F4,10 = 1864, p = .00) of dengue vector (Aedes aegypti) followed by heat-assisted Se-AgNPs and positive control (temephos). Non-significant larvicidal activity was showed by silver (without sericin) which made the temperature stability of silver, debatable. Furthermore, findings of biochemical assays (glutathione-S transferase, esterase, and acetylcholinesterase) showed the levels of resistance in field strain larvae. Aforementioned findings of the study suggests the sonication as the best method for synthesis of Se-AgNPs while the larvicidal activity is inversely proportional to the size of Se-AgNPs, i.e., smallest the size, highest the larvicidal activity. Conclusively, status of the sericin as a natural reducing/stabilizing agent has been endorsed by the findings of this study. RESEARCH HIGHLIGHTS: Incorporation of biocompatible and inexpensive sericin as a capping/reducing agent for synthesis of Se-AgNPs. A novel sonication method was used for the fabrication of Se-AgNPs which were thoroughly characterized by particle size analyzer, UV-visible spectrophotometry, SEM and FTIR. Analysis of enzymatic (GSTs, ESTs) levels in field and lab strains of Aedes aegypti larvae for evaluation of insecticides resistance.

Repellent Screening of Selected Plant Essential Oils Against Dengue Fever Mosquitoes Using Behavior Bioassays.

Among the efforts to reduce mosquito-transmitted diseases, such as malaria and dengue fever, essential oils (EOs) have become increasingly popular as natural replacements for the repellant DEET. In this study, seven commercially available plant EOs against Aedes species mosquitoes were evaluated for their complete protection time (CPT, min) in vivo using human-hand in cage tests (GB2009/China and WHO2009). Among the EOs with the highest efficacy in repelling mosquitoes, Aedes albopictus (Skuse) were clove bud oil and patchouli oil. Both were further assessed according to the in vivo method recommended by the WHO, to determine their minimum effective dose and CPT. A comparison of the ED50 values (dose yielding a 50% repellent response) of these two EOs against Aedes aegypti(L.) showed that the ED50 (2.496 µg/cm2) of patchouli oil was 1248 times higher than that of clove bud oil (0.002 µg/cm2), thus demonstrating them greater efficacy of the latter in repelling Ae. aegypti mosquitoes. For the 2 EOs, eugenol was the major component with higher than 80% in relative amount of the clove bud oil. The patchouli oil had more than 30% of character chemical patchouli alcohol along with α-bulnesene (10.962%), α-guaiene (9.227%), and seychellene (7.566%). Clove bud oil was found to confer longer complete protection than patchouli oil against a common species of mosquito. These results suggest use of EOs as safe, highly potent repellents for use in daily life and against mosquito-transmitted diseases, such as malaria and dengue fever.

Biosynthesis of zinc oxide nanoparticles using Indigofera tinctoria and their efficacy against dengue vector, Aedes aegypti (Diptera: Culicidae).

Dengue fever is a viral mosquito borne disease transmitted by day biting mosquito, Aedes aegypti. No medicine has been proven to be effective for the complete cure of dengue and mosquito control remains to be the only effective option. Increased cases of dengue contraction are being enormously reported worldwide every year. Thus, the urge for an effective measure remains a factor of major concern. In the present study, biosynthesized spherical-like structured zinc oxide (ZnO) nanoparticles using Indigofera tinctoria leaf extracts are employed as a mosquito controlling agent. The biosynthesized nanoparticles are characterized by UV-Vis, FTIR, FESEM, EDAX, XRD, Zeta Potential, and DLS analysis. The efficacy of the green synthesized ZnO nanoparticles were tested against different larval and pupal stages of A. aegypti. Further, it is established that a significant LC50 values of 4.030 ppm in first instar and 7.213 ppm in pupae of A. aegypti is due to the impact of synthesized ZnO. Histological studies confirmed that effective and destructive changes were observed in larval body tissues particularly in the fat cells and the midgut. Therefore, this study highlights the application of biosynthesized ZnO nanoparticles as a potential candidate for safe and eco-friendly agent against the dengue vector, A. aegypti.

Prolonged Repellent Activity of Plant Essential Oils against Dengue Vector, Aedes aegypti.

Repellents are effective personal protective means against outdoor biting mosquitoes. Repellent formulations composed of EOs are finding increased popularity among consumers. In this study, after an initial screening of 11 essential oils (EOs) at the concentration of 33 µg/cm2, five of the most repellent EOs, Perovskia atriplicifolia, Citrus reticulata (fruit peels), C. reticulata (leaves), Mentha longifolia, and Dysphania ambrosioides were further investigated for repellent activity against Aedes aegypti mosquitoes in time span bioassays. When tested at the concentrations of 33 µg/cm2, 165 µg/cm2 and 330 µg/cm2, the EO of P. atriplicifolia showed the longest repellent effect up to 75, 90 and 135 min, respectively, which was followed by C. reticulata (peels) for 60, 90 and 120 min, M. longifolia for 45, 60 and 90 min, and C. reticulata (leaves) for 30, 45 and 75 min. Notably, the EO of P. atriplicifolia tested at the dose of 330 µg/cm2 showed complete protection for 60 min which was similar to the commercial mosquito repellent DEET. Gas chromatographic-mass spectrometric analyses of the EOs revealed camphor (19.7%), limonene (92.7%), sabinene (24.9%), carvone (82.6%), and trans-ascaridole (38.8%) as the major constituents of P. atriplicifolia, C. reticulata (peels), C. reticulata (leaves), M. longifolia, and D. ambrosioides, respectively. The results of the present study could help develop plant-based commercial repellents to protect humans from dengue mosquitoes.

Larvicidal and pupicidal activity of phyto-synthesized zinc oxide nanoparticles against dengue vector aedes aegypti.

This study aimed to assess the phyto-synthesizing potential of Tarenna asiatica methanol leaf extract as well as its larvicidal and pupicidal potential against Aedes aegypti larvae. According to the findings of this study, the methanol leaf extract of T. asiatica has the potential to synthesize zinc oxide nanoparticles from zinc acetate dehydrate. Standard analytical techniques such as UV-visible spectrophotometer, Fourier-transform infrared spectroscopy, X-ray Diffraction analysis, Scanning Electron Microscope, and Energy Dispersive X-Ray were used to characterize the phyto-synthesized nanoparticles. The zinc oxide nanoparticles synthesized ranged in size from 22.35 to 31.27 nm and was spherical in shape. These nanoparticles demonstrated excellent larvicidal activity against Aedes aegypti larvae in the second, third, and fourth in stars, as well as significant pupicidal activity. These findings suggest that the methanol leaf extract of T. asiatica synthesized zinc oxide nanoparticles, which could be used to develop mosquito repellents.

Influence of Religiosity and Spirituality on the Adoption of Behaviors of Epidemiological Relevance in Emerging and Re-Emerging Diseases: The Case of Dengue Fever.

Emerging and re-emerging diseases are responsible for recurrently affecting the health of human populations. Although people are aware of these diseases, they do not seem to adopt prophylactic methods to prevent them. Here, we propose to investigate the influence of religiosity/spirituality (R/S) on the frequency of the adoption of prophylactic behaviors and the perception of risk of vulnerability to the disease. We used dengue, which is a seasonal arboviral disease in Brazil, as a model. To measure the dimensions of religiosity/spirituality, we used the Portuguese version of the Brief Multidimensional Measure of Religiosity/Spirituality questionnaire. All data were obtained through a structured questionnaire that was answered online by 204 volunteers living throughout Brazil. Our results indicate that R/S is predictive of the frequency of prophylactic behaviors (p = 0.0222, R2 = 0.025) and the perception of risk of vulnerability (p < 0.05, R2 = 0.07). We argue that the effect of R/S on health occurs through the promotion of salutogenic mechanisms promoted by socialization in religious environments. This can help understand social dynamics in epidemiological crises and mitigate the influence of these diseases.

Bioefficacy of Epaltes divaricata (L.) n-Hexane Extracts and Their Major Metabolites against the Lepidopteran Pests Spodoptera litura (fab.) and Dengue Mosquito Aedes aegypti (Linn.).

The present research investigated the chemical characterization and insecticidal activity of n-Hexane extracts of Epaltes divaricata (NH-EDx) along with their chief derivatives n-Hexadecanoic acid (n-HDa) and n-Octadecanoic acid (n-ODa) against the dengue vector Aedes aegypti and lepidopteran pest Spodoptera litura. Chemical screening of NH-EDx through GC-MS analysis delivered nine major derivatives, and the maximum peak area percentage was observed in n-Hexadecanoic acid (14.63%) followed by n-Octadecadienoic acid (6.73%). The larvicidal activity of NH-EDx (1000 ppm), n-HDa (5 ppm), and n-ODa (5 ppm) against the A. aegypti and S. litura larvae showed significant mortality rate in a dose-dependent way across all the instars. The larvicidal activity was profound in the A. aegypti as compared to the S. litura across all the larval instars. The sublethal dosages of NH-EDx (500 ppm), n-HDa (2.5 ppm), and n-ODa (2.5 ppm) also showed alterations in the larval/pupal durations and adult longevity in both the insect pests. The enzyme activity revealed that the α- and ß-carboxylesterase levels were decreased significantly in both the insect pests, whereas the levels of GST and CYP450 uplifted in a dose-dependent manner of NH-EDx, n-HDa, and n-ODa. Correspondingly, midgut tissues such as the epithelial layer (EL), gut lumen (GL), peritrophic matrix (Pm), and brush border membrane (BBM) were significantly altered in their morphology across both A. aegypti and S. litura against the NH-EDx and their bioactive metabolites. NH-EDx and their bioactive metabolites n-HDa and n-ODa showed significant larvicidal, growth retardant, enzyme inhibition, and midgut toxicity effects against two crucial agriculturally and medically challenging insect pest of ecological importance.

Identification and characterization of new potent inhibitors of dengue virus NS5 proteinase from Andrographis paniculata supercritical extracts on in animal cell culture and in silico approaches.

ETHNOPHARMACOLOGICAL RELEVANCE: About 2.5 billion peoples are at risk of dengue virus and the majority of people, use traditional plant-based medicines to combat dengue. The whole plant of Andrographis paniculata used traditionally over past decades for health promotion. Andrographolide isolated from Andrographis paniculata is used as natural remedy for the treatment of various diseases in different parts of the world. Andrographolide has been reported to have antiviral activity against hepatitis B virus, hepatitis C virus, herpes simplex virus, influenza virus, chikungunya virus, dengue virus 2 and 4. AIM OF THE STUDY: The aim of the present study to isolate the andrographolide from the A. paniculata by supercritical fluid extraction technique and to characterize the isolated compound along with it anti-dengue activity against DENV-2 in vitro and in silico methods. MATERIALS AND METHODS: Supercritical extraction condition for A. paniculata was standardised to isolate andrographolide compound at definite temperature and pressure on the basis of previous study. The andrographolide was identified by using Ultraviolet-Visible Spectroscopy (UV-VIS), Fourier-Transform Infrared Spectroscopy (FT-IR) and High Performance Thin Layer Chromatography (HPTLC) and Proton Nuclear Magnetic Resonance (1HNMR). The maximum non-toxic dose of isolated andrographolide was detected by MTT assay using a micro plate reader at 595 nm. One hundred (100) copies/ml of the DENV-2 virus was used for antiviral assay in C6/36 cells lines and inhibition of virus due to andrographolide was determined by real-time PCR assay. The purity of isolated andrographolide was determined by Differential Scanning Calorimetry (DSC). The dengue NS5 receptor protein was docked with andrographolide and evaluated on the basis of the total energy and binding affinity score by Auto Dock (V4.2.6) software. RESULTS: Andrographolide, a diterpene lactone was isolated from the A. paniculata supercritical extract at 40 °C temperature and 15 Mpa pressure. UV spectrophotometer analysis revealed that the curve of andrographolide plant extract was overlapped with reference compound at 228 nm and the similar bands were detected from FT-IR spectroscopy analysis at 3315, 2917, 2849, 1673, 1462 and 1454 cm-1 in isolated and standard andrographolide. HPTLC analysis shows the retention factor (Rf) of A. paniculata extract at 0.74 ± 0.06 as similar to standard andrographolide Rf values. The purity of isolated andrographolide was 99.76%. The maximum non-toxic dose of isolated andrographolide was found as 15.62 µg/ml on the C6/36 cell line calculated by using MTT assay. The andrographolide showed the 97.23% anti-dengue activity against the dengue-2 virus in C6/36 cell lines. Results of molecular docking showed that the interaction between andrographolide and NS5 of dengue protein with the maximum binding energy as -7.35 kcal/mol. CONCLUSIONS: It is concluded that isolated andrographolide from the A. paniculata possess anti-dengue activity against dengue-2 virus as revealed from in vitro and in silico method. Due to lack of the vaccine and anti-viral agents, andrographolide extracted from A. paniculata play a major role to inhibit the dengue replication. Hence, it could be a source for drug design and help to reduce the dengue infection.

Larvicidal activity of piperovatine and dichloromethane extract from Piper corcovadensis roots against mosquitoes Aedes aegypti L / Actividad larvicida de piperovatina y extracto de diclorometano de las raíces de Piper corcovadensis contra mosquitos vectores del dengue Aedes aegypti L

The research of new substances capable of controlling the Aedes aegypti mosquito is urgent due to the increase in the transmission of the diseases such as dengue, chikungunya and Zika virus by the vector. Thus, the aim of this study was to evaluate the larvicidal activity of crude extract of Piper corcovadensis roots, a native plant from Brazil, and of the isolated compound piperovatine against larvae of A. aegypti by the larval immersion test. The lethal concentration that killed 50% (LC50) and 99% (LC99) of larvae was determined by Probit analysis. The results indicated high larvicidal activity on A. aegypti larvae for crude extract of Piper corcovadensis roots with LC50 of 4.86 µg/mL and LC99 of 15.50 µg/mL and piperovatine with LC50 of 17.78 µg/mL and LC99 of 48.55 µg/mL. This work opens new perspectives to the development of future products with crude extract of Piper corcovadensis roots and piperovatine that can be applied to mosquito control.

La investigación de nuevas sustancias capaces de controlar el mosquito Aedes aegypti es urgente debido al aumento en la transmisión de enfermedades como el dengue, el chikungunya y el virus Zika por el vector. Por lo tanto, el objetivo de este estudio fue evaluar la actividad larvicida del extracto crudo de las raíces de Piper corcovadensis, una planta nativa de Brasil, y del compuesto aislado piperovatine contra larvas de A. aegypti mediante la prueba de inmersión larvaria. La concentración letal que mató al 50% (LC50) y al 99% (LC99) de larvas se determinó mediante análisis Probit. Los resultados indicaron una alta actividad larvicida en larvas de A. aegypti para extracto crudo de las raíces de Piper corcovadensis con LC50 de 4.86 µg/mL y LC99 de 15.50 µg/mL y piperovatine con LC50 de 17.78 µg/mL y LC99 de 48.55 µg/mL. Este trabajo abre nuevas perspectivas para el desarrollo de futuros productos con extracto crudo de las raíces de Piper corcovadensis y piperovatine que pueden aplicarse al control de mosquitos.

Larvicididal Activity of Natural Repellents Against the Dengue Vector, Aedes aegypti.

The present research aimed to evaluate the larvicidal activity of several recently discovered natural repellents formulated in lotions against larvae of Aedes aegypti. We used a modified larval bioassay method by the World Health Organization standards in evaluating larval mortality at 24-, 48-, and 72-h exposure. Among the test repellents, 2-undecanone showed 100% mortality of Ae. aegypti larvae, followed by catnip oil, capric acid, coconut oil fatty acids, methyl caprate, methyl laurate, and coconut oil methyl esters. The repellent, 2-undecanone showed median lethal concentration (LC50) values of 73.07, 26.45, and 15.68 ppm at 24-, 48-, and 72-h exposure, respectively. Larvicidal activity varied among the other repellents tested.

Target and non-target botanical pesticides effect of Trichodesma indicum (Linn) R. Br. and their chemical derivatives against the dengue vector, Aedes aegypti L.

The effects of crude ethanol derived leaf extract Trichodesma indicum (Linn) (Ex-Ti) and their chief derivatives were accessed on the survival and development of the dengue mosquito Ae. aegypti also their non-toxic activity against mosquito predator. T. indicum is recognized to be the vital weed plant and a promising herb in the traditional ayurvedic medicine. In this study, the GC-MS chromatogram of Ex-Ti showed higher peak area percentage for cis-10-Heptadecenoic acid (21.83%) followed by cycloheptadecanone (14.32%). The Ex-Ti displayed predominant mortality in larvae with 96.45 and 93.31% at the prominent dosage (200 ppm) against III and IV instar. Correspondingly, sub-lethal dosage against the enzymatic profile of III and IV instar showed downregulation of α,ß-carboxylesterase and SOD protein profiles at the maximum concentration of 100 ppm. However, enzyme level of GST as well as CYP450 increased significantly dependent on sub-lethal concentration. Likewise, fecundity and hatchability of egg rate of dengue mosquito decreased to the sub-lethal concentration of Ex-Ti. Repellent assay illustrates that Ex-Ti concentration had greater protection time up to 210 min at 100 ppm. Also, activity of Ex-Ti on adult mosquito displayed 100% mortality at the maximum dosage of 600, 500 and 400 ppm within the period of 50, 60 and 70 min, respectively. Photomicrography screening showed that lethal dosage of Ex-Ti (100 ppm) produced severe morphological changes with dysregulation in their body parts as matched to the control. Effects of Ex-Ti on the Toxorhynchites splendens IV instar larvae showed less mortality (43.47%) even at the maximum dosage of 1500 ppm as matched to the chemical pesticide Temephos. Overall, the present research adds a toxicological valuation on the Ex-Ti and their active constituents as a larvicidal, repellent and adulticidal agents against the global burdening dengue mosquito.

Dengue Knowledge, Attitudes, and Practices Among Arizona Health Care Providers, 2014-2015.

Background: Detection of local dengue transmission requires an aware and engaged medical community, as health care providers are the front line of public health surveillance. To assess the knowledge, attitude, and practice about dengue, an online survey was distributed among Arizona health care providers during 2014 and 2015. Materials and Methods: The survey consisted of a total of 10 knowledge, attitude, and practice questions divided as follows: 5 knowledge questions, 2 attitude questions, and 3 practice questions. The link to the Qualtrics survey was distributed through the Arizona Health Alert Network to a total of 4582 e-mail addresses, of which 335 participants opened the survey, and 196 completed and submitted their responses. Results: Less than half the respondents reported choosing the right dengue diagnostic test (40.4%) or understanding the epidemiology of dengue in Arizona (40.9%). Slightly more than half the respondents reported frequently asking for travel history (59%), and three-fourth of them would notify the local health department on suspicion of a dengue patient (76.1%). Survey score was associated with providers specialized in infectious diseases (1.88, 95% CI: 0.42-3.33, p = 0.01), medical doctors or doctors of osteopathic medicine (1.82, 95% CI: 0.98-2.65, p < 0.0001), and respondents who reported to have heard about the increase in dengue cases in Sonora (Mexico) in fall 2014 (1.51, 95% CI: 0.67-2.34, p = 0.0005), indicating better survey performance. Conclusions: These results indicate that education for health care providers on dengue should be improved particularly among general practice noninfectious disease providers who might be the first point of care for dengue patients. Findings suggest that additional training on clinical management, asking travel history, and notifying the local health department on suspicion of a dengue patient are needed.

Chemical composition, Aedes mosquito larvicidal activity, and repellent activity against Triatoma rubrofasciata of Severinia monophylla leaf essential oil.

Aedes aegypti and Ae. albopictus are key vectors in the spread of arboviruses such as dengue, chikungunya, yellow fever, and Zika. Triatoma rubrofasciata is an "assassin bug" whose populations and association with humans have dramatically increased and may represent a serious health concern. Control of insect vectors is a logical course of action to prevent the spread of these insect-borne infections. This work presents the leaf essential oil composition, mosquito larvicidal activities, and insect-repellent activity of Severinia monophylla. The essential oil of S. monophylla from Vietnam was obtained by hydrodistillation and analyzed by gas chromatography and mass spectrometry. The major components were sabinene, ß-caryophyllene, bicyclogermacrene, germacrene D, (E)-nerolidol, globulol, and linalool. The leaf essential oil showed remarkable larvicidal activity against Ae. aegypti with LC50 (48 h) of 7.1 µg/mL and Ae. albopictus with LC50 (48 h) of 36 µg/mL. The essential oil also showed repellent activity on T. rubrofasciata at a concentration of 0.5%.