Laboratory evaluation of the efficacy of deltamethrin-laced attractive toxic sugar bait formulation on Anopheles stephensi.

BACKGROUND: Attractive toxic sugar bait (ATSB) is a promising "attract and kill"-based approach for mosquito control. It is a combination of flower nectar/fruit juice to attract the mosquitoes, sugar solution to stimulate feeding, and a toxin to kill them. Selecting an effective attractant and optimizing concentration of toxicant is significant in the formulation of ATSB. METHODS: Current study formulated an ATSB using fruit juice, sugar and deltamethrin, a synthetic pyrethroid. It was evaluated against two laboratory strains of Anopheles stephensi. Initial studies evaluated comparative attractiveness of nine different fruit juices to An. stephensi adults. Nine ASBs were prepared by adding fermented juices of plum, guava, sweet lemon, orange, mango, pineapple, muskmelon, papaya, and watermelon with 10% sucrose solution (w/v) in 1:1 ratio. Cage bioassays were conducted to assess relative attraction potential of ASBs based on the number of mosquito landings on each and the most effective ASB was identified. Ten ATSBs were prepared by adding the identified ASB with different deltamethrin concentrations (0.015625-8.0 mg/10 mL) in 1:9 ratio. Each ATSB was assessed for the toxic potential against both the strains of An. stephensi. The data was statistically analysed using PASW (SPSS) software 19.0 program. RESULTS: The cage bioassays with nine ASBs revealed higher efficacy (p < 0.05) of Guava juice-ASB > Plum juice-ASB > Mango juice-ASB in comparison to rest of the six ASB's. The bioassay with these three ASB's ascertained the highest attractancy potential of guava juice-ASB against both the strains of An. stephensi. The ATSB formulations resulted in 5.1-97.9% mortality in Sonepat (NIMR strain) with calculated LC30, LC50, and LC90 values of 0.17 mg deltamethrin/10 mL, 0.61 mg deltamethrin/10 mL, and 13.84 mg deltamethrin/10 mL ATSB, respectively. Whereas, 6.12-86.12% mortality was recorded in the GVD-Delhi (AND strain) with calculated LC30, LC50, and LC90 values of 0.25 mg deltamethrin/10 mL, 0.73 mg deltamethrin/10 mL and 10.22 mg deltamethrin/10 mL ATSB, respectively. CONCLUSION: The ATSB formulated with guava juice-ASB and deltamethrin (0.0015625-0.8%) in 9:1 ratio showed promising results against two laboratory strains of An. stephensi. Field assessment of these formulations is being conducted to estimate their feasibility for use in mosquito control.

Reversion of CYP450 monooxygenase-mediated acetamiprid larval resistance in dengue fever mosquito, Aedes aegypti L.

Aedes-borne diseases are on the rampant rise despite continued application of chemical insecticide-based interventions. The appearance of high degree of insecticide resistance in Aedes species and noxious effects on environment and non-targets have raised further concerns. Among new chemical interventions, neonicotinoids are considered a safe and effective approach. The present study investigated the control potency of acetamiprid and development of resistance in Aedes aegypti larvae; and the involvement of CYP450 monooxygenases in inducing resistance. The early fourth instars of Ae. aegypti parent susceptible strain (PS) were selected with acetamiprid for 15 generations (ACSF strain) increasing the resistance to 19.74-fold in ACSF-10 and 36.71-fold in ACSF-15. The ACSF-10 larvae were assayed with acetamiprid combined with piperonyl butoxide (PBO) in three different ratios (1:1, 1:5 and 1:10) and selected for next five generations with 1:10 combination. Selection with synergized acetamiprid (APSF strains) reversed as well as reduced the rate of resistance development resulting in only 1.35-fold resistance in APSF-15. The APSF strains showed %monooxygenase dependency ranging from 86.71 to 96.72%. The estimation of the monooxygenases levels in parent and selected larvae showed increased monooxygenase level in the ACSF strains by 2.42-2.87-fold. The APSF-15 strains exhibited 57.95% lower enzyme production than ACSF-15 strain. The reduction and reversion of resistance by using PBO and the elevated levels of monooxygenases in ACSF and reduction in APSF strains recommend the involvement of CYP450-mediated mechanism in the development of acetamiprid resistance in Ae. aegypti. These studies could help in devising resistance management strategies in order to preserve the efficiency of pre-existing insecticides.

Ascertaining variations in the activity of larval midgut enzymes of Helicoverpa armigera by dietary emamectin benzoate through biochemical and in silico docking study.

Helicoverpa armigera, a ubiquitous polyphagous pest, poses a significant threat to global agriculture, causing substantial economic losses and demonstrating resistance to synthetic pesticides. This study investigates the potential of emamectin benzoate (EMB), an avermectin derivative, as an effective control agent against H. armigera. The larvae of the NBII-MP-NOC-01 strain of H. armigera were reared on an artificial diet. The impact of dietary EMB was examined on four midgut enzymes; alanine aminotransferase (ALT), aspartate aminotransferase (AST), acid phosphatase (ACP), and alkaline phosphatase (ALP). Results showed a dose-dependent and time-dependent reduction in ALT and AST activity, while an initial increase and subsequent decline in ACP and ALP activity at higher EMB concentrations. Computational modelling of enzyme structures and molecular docking studies revealed differential binding of EMB with the midgut enzymes. The strongest interaction was observed between EMB and ALT residues, contrasting with weakest interactions observed with AST. The study also showed that decreased activity of transaminases in H. armigera caused by EMB may be because of stability-activity trade-off, while in phosphatases reverse may be the case. This research provides crucial insights into the biochemical responses and the intricate insecticide-enzyme interactions in H. armigera caused by EMB exposure. This study lays the foundation for further research aimed at developing environmentally friendly approaches for managing H. armigera, addressing the challenges associated with conventional pesticides.

Development of Deltamethrin-Laced Attractive Toxic Sugar Bait to Control Aedes aegypti (Linnaeus) Population.

Background: The attractive toxic sugar bait (ATSB) is a promising strategy for controlling mosquitoes at the adult stage. The strategy is based on the use of a combination of fruit juice, sugar, and a toxin in order to attract and kill the adult mosquitoes. The selection of the components and optimization of their concentrations is significant for the formulation of an effective ATSB. Methods: The present study formulated nine ATSBs and evaluated their efficacy against two laboratory strains (AND-Aedes aegypti and AND-Aedes aegypti-DL10) and two wildcaught colonized strains of Aedes aegypti (GVD-Delhi and SHD-Delhi). Initially, nine attractive sugar baits (ASBs) were prepared using a mixture of 100% fermented guava juice (attractant) with 10% sucrose solution (w/v) in 1 : 1 ratio. ATSBs were formulated by mixing each ASB with different concentrations of deltamethrin in the ratio of 9 : 1 to obtain final deltamethrin concentration of 0.003125-0.8 mg/10 mL ATSB. Cage bioassays were conducted with 50 mosquitoes for 24 h in order to evaluate the efficacy of each ATSB against the four strains of Ae. aegypti. The data were statistically analyzed using PASW software 19.0 program and 2-way ANOVA. Results: The ATSB formulations registered 8.33-97.44% mortality against AND-Aedes aegypti and 5.15-96.91% mortality against AND-Aedes aegypti-DL10 strains of Ae. aegypti, while GVD-Delhi strain registered 2.04-95.83% mortality and SHD-Delhi strain showed 5.10-97.96% mortality. The administration of 0.8 mg of deltamethrin within 10 mL of attractive toxic sugar bait (ATSB) has led to the maximum mortality rate in adult mosquitoes. Conclusions: The ATSBs formulated with guava juice-ASB and deltamethrin (9 : 1) showed toxin dose-dependent toxicity by all the four strains of Ae. aegypti. Most effective dosage was found as 0.8 mg deltamethrin/10 mL ATSB which imparted 96% to 98% mortality in adult mosquitoes. The investigations demonstrated the efficacy of deltamethrin-laced ATSB formulations against Ae. aegypti and highlighted the need for conduct of structured field trials and investigating the impact on disease vectors and nontarget organisms.

Impact of Argemone mexicana extracts on the cidal, morphological, and behavioral response of dengue vector, Aedes aegypti L. (Diptera: Culicidae).

The larvicidal, behavioral, and morphological response of dengue vector, Aedes aegypti treated with deleterious weed, Argemone mexicana, was explored. The 1,000 ppm extracts of A. mexicana leaf, stem, and roots prepared in five different solvents (petroleum ether, hexane, benzene, acetone, and ethanol) were screened for their larvicidal activity against dengue vector establishing the efficacy of petroleum ether and hexane extracts. Other extracts, unable to give 100% mortality, were considered ineffective and discarded from further study. Larvicidal bioassay conducted with selected extracts confirmed the higher efficacy of hexane extracts exhibiting 1.1- to 1.8-fold more potential than the petroleum ether extracts. The results further revealed 1.6- to 2.4-fold higher efficacy of root extracts than those prepared from the leaves and stem of A. mexicana. The hexane root extract of A. mexicana was found to be the most effective larvicide with LC50 value of 91.331 ppm after 24 h of exposure causing 1.8 and 2.4 fold more toxicity as compared to the hexane leaf and stem extracts, respectively. Prolonged exposure of the larvae to the extracts resulted in increased toxicity potential of the extracts. Observations of the treated larvae revealed excitation, violent vertical, and horizontal movements with aggressive anal biting behavior suggesting effect of extracts on their neuromuscular system. Morphological studies of the treated larvae revealed the demelanization of cuticle and shrinkage of internal cuticle of anal papillae indicating the anal papillae as the probable action sites of the A. mexicana extracts. The potential of A. mexicana as new larvicides against dengue vector are being explored.

Larvicidal efficacy of the Citrus limetta peel extracts against Indian strains of Anopheles stephensi Liston and Aedes aegypti L.

The extracts from the peels of Citrus limetta were prepared using hexane and petroleum ether as the solvents. The larvicidal potential of each extract was assessed against dengue fever vector, Aedes aegypti, and malarial vector, Anopheles stephensi, by evaluating the toxicity effects on early fourth instars. Both the extracts were found effective against both the species. The bioassay with hexane extracts resulted in LC(50) values of 132.45 and 96.15 ppm against A. stephensi and A. aegypti, respectively; while the petroleum ether extracts from the C. limetta peels showed LC(50) values of 244.59 and 145.50 ppm, respectively. It revealed that the hexane extracts possessed 1.9-fold more larvicidal potential against A. stephensi and 1.5-fold more efficacy against A. aegypti as compared to the extracts obtained using petroleum ether as solvent. The data further revealed that the extracts were 1.4-1.7 times more effective against A. aegypti as compared to A. stephensi. The qualitative phytochemical study of the extracts showed the presence of terpenoids and flavonoids as the common phytochemical constituents in the extracts suggesting their possible role in the toxicity. Other constituents tested were not detected except alkaloids which were found to be present only in the petroleum ether extract. Further studies are needed to isolate and identify the active principles involved, their mode of action, formulated preparations for enhancing potency and stability, toxicity, and effects on non-target organisms and the environment. This could help in formulating efficient strategies for mosquito control.

Metabolic detoxification and ace-1 target site mutations associated with acetamiprid resistance in Aedes aegypti L.

Despite the continuous use of chemical interventions, Aedes-borne diseases remain on the rise. Neonicotinoids are new, safer, and relatively effective pharmacological interventions against mosquitoes. Neonicotinoids interact with the postsynaptic nicotinic acetylcholine receptors (nAChRs) of the insect central nervous system, but the absence of nAChR polymorphism in resistant phenotypes makes their involvement in neonicotinoid resistance uncertain. Thus, an investigation was carried out to understand the role of metabolic detoxification and target site insensitivity in imparting acetamiprid resistance in Aedes aegypti larvae. Studies were conducted on the parent susceptible strain (PS), acetamiprid-larval selected strain for five generations (ACSF-5; 8.83-fold resistance) and 10 generations (ACSF-10; 19.74-fold resistance) of Ae. aegypti. The larval selection raised α-esterase and ß-esterase activities by 1.32-fold and 1.34-fold, respectively, in ACSF-10 as compared to PS, while the corresponding glutathione-S-transferase and acetylcholinesterase activity increased by 22.5 and 2%. The ace-1 gene in PS and ACSF-10 showed four mismatches in the 1312-1511 bp region due to mutations in the Y455C codon (tyrosine to cysteine) at the 1367th position (TAC→TGC); I457V codon (isoleucine to valine) at 1372 bp and 1374 bp (ATA→GTG); and R494M codon (arginine to methionine) at 1484 bp (AGG→ATG). The R494M mutation was the novel and dominant type, observed in 70% ACSF-10 population, and has not been reported so far. The studies evidenced the combination of metabolic detoxification and target site mutation in imparting acetamiprid resistance in Ae. aegypti.

Morphological and physiological changes induced by Achyranthes aspera-mediated silver nanocomposites in Aedes aegypti larvae.

Aedes aegypti is responsible for the global spread of several ailments such as chikungunya, dengue, yellow fever, and Zika. The use of synthetic chemicals is the primary intervention in mosquito management. However, their excessive utilization resulting in the spread of toxic ingredients in the environment and posing threats to beneficial organisms has prompted the recommendation for the use of biologically synthesized nanocomposites as a promising approach for vector control. Silver nanocomposites were synthesized using leaf (AL-AgNCs) and stem (AS-AgNCs) extracts of Achyranthes aspera. The early fourth instars of A. aegypti were exposed to lethal doses of these nanocomposites to evaluate their effects on larval development, behavior, morphology, and mid-gut histoarchitecture. The cellular damage and deposition of nanocomposite residues in the mid-gut were studied using light and transmission electron microscopy. The A. aspera silver nanocomposite (AA-AgNC)-exposed larvae exhibited dose-dependent extended duration of development and diminished adult emergence, but did not exhibit modified behavior. Intense damage to the cuticle membrane and slight contraction in the internal membrane of anal papillae were noticed. Morphologically, the mid-gut appeared disorganized, darkly pigmented, and shrunk. Histological investigations of the mid-gut revealed significantly disordered internal architecture with lysed cells, damaged peritrophic membrane and microvilli, disintegrated epithelial layer, and a ruptured and displaced basement membrane. Visualization of the larval mid-gut through TEM showed severe cellular damage and aggregation of black spots, indicating the deposition of silver particles released by AA-AgNCs. The investigations revealed the bio-efficacy of A. aspera-mediated AgNCs against A. aegypti inducing stomach and contact toxicity in the larvae. The utilization of AA-AgNCs is recommended for A. aegypti management as a safe and effective intervention.

A novel RP-HPLC method for quantification of cholinesterase activity in human blood: An application for assessing organophosphate and carbamate insecticide exposure.

Several methods have been reported to estimate Acetylcholinesterase (AChE) enzyme activity in blood samples. The Ellman assay is the most important among all but with several shortcomings, and there is a need to develop a method which is accurate, sensitive and quick for analyzing AChE. Therefore, we have developed an assay utilizing RP-HPLC with UV detection for the determination of AChE activity. This method measured the conversion of 1-naphthol acetate to 1-naphthol to estimate AChE activity in blood samples. Performance was judged on the basis of reproducibility, sensitivity, accuracy, and the ability to screen enzyme activity within 20minutes. A series of experiments were performed, varying the concentration of blood and substrate, with optimal sensitivity using 50 µM substrate and 10µL blood. The validation parameters such as linearity (R2 of ≥ 0.9842 for 1-naphthol and ≥ 0.9897 for 1-naphthol acetate), precision (94.21-96.41%), accuracy (85.2%-99.6% and 82.6%-99.3% for 1-naphthol and 1-naphthol acetate respectively), and robustness were validated according to International Conference on Harmonization (ICH) guidelines. Blood samples were collected from healthy people, farmers exposed to spraying of pesticides, and suicidal patients who ingested pesticides and were hospitalized and were analyzed by the developed method. The AChE level was approximately 21 units/mL compared to 24units/mL in controls, whereas suicidal patients showed the least AChE levels of 1 unit/mL. The employment of this method is recommended for estimating AChE level on various matrices.

Attractive Sugar Bait Formulation for Development of Attractive Toxic Sugar Bait for Control of Aedes aegypti (Linnaeus).

Background: Attractive toxic sugar bait (ATSB), based on "attract and kill" approach, is a novel and promising strategy for mosquito control. Formulation of an attractive sugar bait (ASB) solution by selecting an efficient olfaction stimulant and preparation of an optimized sugar-attractant dosage is a significant component for the success of the approach. Methods: Current study evaluated relative potential of nine ASBs, formulated by combination of sugar and fresh fruit juices (guava, mango, muskmelon, orange, papaya, pineapple, plum, sweet lemon, and watermelon) in attracting Aedes aegypti adults. Freshly extracted and 48-hour-fermented juices were combined with 10% sucrose solution (w/v) in 1 : 1 ratio. Cage bioassays were conducted against two laboratory strains (susceptible: AND-Aedes aegypti; deltamethrin-selected: AND-Aedes aegypti-DL10) and two field-collected strains (Shahdara strain of Aedes aegypti: SHD-Delhi; Govindpuri strain of Aedes aegypti: GVD-Delhi). Each of the nine ASBs was assayed, individually or in groups of three, for its attraction potential based on the relative number of mosquito landings. The data were analysed for statistical significance using PASW (SPSS) software 19.0 program. Results: The prescreening bioassay with individual ASB revealed significantly higher efficacy of ASB containing guava/plum/mango juice than that containing six other juices (p < 0.05) against both the laboratory and field strains. The bioassay with three ASBs kept in one cage, one of the effective ASBs and two others randomly selected ASBs, also showed good attractancy of the guava/plum/mango juice-ASB (p < 0.05). The postscreening assays with these three ASBs revealed maximum attractant potential of guava juice-sucrose combination for all the four strains of Ae. aegypti. Conclusion. Guava juice-ASB showed the highest attractancy against both laboratory and field-collected strains of Ae. aegypti and can be used to formulate ATSB by combining with a toxicant. The field studies with these formulations will ascertain their efficacy and possible use in mosquito management programs.

Oviposition-altering and ovicidal potentials of five essential oils against female adults of the dengue vector, Aedes aegypti L.

The oviposition deterrence and ovicidal potential of five different essential oils, peppermint oil (Mentha piperita), basil oil (Ocimum basilicum), rosemary oil (Rosemarinus officinalis), citronella oil (Cymbopogon nardus), and celery seed oil (Apium graveolens), were assessed against female adults of the dengue vector, Aedes aegypti L. Multiple concentration tests were carried out where cups containing 1 mL of different concentrations (100%, 10%, 1%, 0.1%) of the oils and 199 mL of water were used for oviposition. The number of eggs laid and the larvae hatched in each cup were scored to evaluate the oviposition deterrent and ovicidal potentials of the oils. Our investigations revealed that the addition of 100% oil (pure oil) caused complete oviposition deterrence except in A. graveolens which resulted in 75% effective repellency. The use of 10% oil resulted in the maximum deterrence of 97.5% as shown by the M. piperita oil while other oils caused 36-97% oviposition deterrence as against the control. The oviposition medium with 1% oil showed decreased deterrent potential with 30-64% effective repellency, the M. piperita oil being exceptional. However, as the concentrations of the oil were reduced further to 0.1%, the least effective oil observed was A. graveolens (25% ER). Also, the M. piperita oil showed much reduced activity (40%) as compared to the control, while the other oils exhibited 51-58% repellency to oviposition. The studies on the ovicidal effects of these oils revealed that the eggs laid in the water with 100% essential oils did not hatch at all, whereas when 10% oils were used, only the R. officinalis oil resulted in 28% egg hatch. At lower concentrations (1%), the oils of M. piperita, O. basilicum, and C. nardus showed complete egg mortality while those of A. graveolens and R. officinalis resulted in 71% and 34% egg hatches, respectively. When used at 0.1%, the O. basilicum oil was found to be the only effective oil with 100% egg mortality, whereas other oils resulted in 16-76% egg mortality, the least mortality caused by the A. graveolens oil. These results suggest that these essential oils can be employed in a resistance-management program against A. aegypti. Further detailed research is needed to identify the active ingredient in the extracts and implement the effective mosquito management program.

Impact of Parthenium hysterophorus leaf extracts on the fecundity, fertility and behavioural response of Aedes aegypti L.

Different extracts of 1,000 ppm were prepared from the leaves of Parthenium hysterophorus using acetone, benzene, petroleum ether, diethyl ether and hexane as the solvents. The efficacy of each extract was assessed against dengue fever vector, Aedes aegypti by evaluating the variations in fecundity, fertility and behavioural response of the female adults. The leaf extracts could cause 70-100% repellency in the oviposition behaviour of the adults. The diethyl ether extract was found to be the most effective extract resulting in maximum effective repellency (99.7%) leading to the highest levels of reduced fecundity and 100% egg mortality followed by benzene extracts causing 93.8% reduced oviposition and 100% ovicidal effect. Hexane and acetone extracts with the least oviposition deterrence of 70-74% and negligible egg mortality (8-9%) proved to be the least effective extracts. The petroleum ether extract had a moderate impact resulting in 93.2% diminished fecundity and 41% ovicidal effect. The behavioural response of female adults of A. aegypti was evaluated by performing spatial repellency and contact irritancy assays. The most significant spatial repellency behaviour was elicited by acetone extracts leading to escape of 80% mosquitoes. Hexane and diethyl ether extracts could cause moderate response with 50-60% escape, while a slight and no reaction was observed on exposure to petroleum ether and benzene extracts, respectively. An interesting observation was the knocked-down activity caused by the hexane extracts with no recovery even after 24 h. A significant contact irritancy response was noticed in the mosquitoes on exposure to acetone leaf extracts resulting in first flight only after 4 s and a total of 12 flights during exposure. No irritancy behaviour was observed on exposure to diethyl ether and benzene leaf extracts. However, as against controls, a slight irritability response was noticed on exposure to hexane leaf extracts resulting in relative irritability of 1.2. Our results suggest the selective efficiency of Parthenium leaf extracts against A. aegypti, as the most effective oviposition deterrent and ovicidal agent was least effective as irritant extract and vice-versa. Further detailed research is needed to identify the active ingredient in the extracts and implement the effective mosquito management programme.

Larvicidal potential of ethanolic extracts of dried fruits of three species of peppercorns against different instars of an indian strain of dengue fever mosquito, Aedes aegypti L. (Diptera: Culicidae).

Larvicidal bioassay was carried out in the laboratory to assess the potential of ethanolic extracts of dried fruits of three species of peppercorns: Long pepper, Piper longum L., Black pepper, Piper nigrum, and White pepper, Piper nigrum against the different instars of field-collected Indian strain of dengue fever mosquito (Aedes aegypti L.). The investigations established the larvicidal potential of all the varieties of pepper fruits against Ae. aegypti. Against early fourth instar, the ethanolic extracts of Black and White P. nigrum proved to be 30-40% less toxic than the extracts of P. longum, whereas against third instars, white pepper extracts exhibited 7% more efficacy than that of black pepper and 47% more toxicity than that of long pepper. The results also revealed that the extracts of all the three pepper species were 11-25 times more toxic against the third instar larvae as compared to the early fourth instars. The lethal concentration, 50% (LC(50)) values obtained with ethanolic extracts of P. longum, White P. nigrum and Black P. nigrum against early fourth instar larvae were 0.248, 0.356, and 0.405 ppm, respectively, and the lethal concentration, 90% (LC(90)) values were 0.605, 0.758, and 0.801 ppm, respectively. Whereas against third instar larvae, the LC(50) values recorded with three extracts were 0.022, 0.015, and 0.016 ppm and the LC(90) values recorded were 0.054, 0.034, and 0.046 ppm, respectively. The larvae treated with all the pepper species showed initial abnormal behavior in their motion followed by excitation, convulsions, and paralysis, leading to 100% kill indicating delayed larval toxicity and effects of the extracts on the neuromuscular system. Observations of morphological alterations on treated larvae under light microscopy revealed that most organs, except anal papillae, had a normal structural appearance as that of controls. The structural deformation in the form of shrinkage in the internal membrane exhibited by anal papillae suggests the anal papillae as the probable action sites of the pepper extracts. The potential of peppercorns as new types of larvicides for the control of mosquitoes are explored.

A facile and rapid method for green synthesis of Achyranthes aspera stem extract-mediated silver nano-composites with cidal potential against Aedes aegypti L.

Aedes aegypti L. is the primary vector associated with transmission of globally concerned diseases; Zika, yellow fever, dengue and Chikungunya. Present study investigates an efficient, alternative and comparative approach for mosquito control which is safe to environment and non-target organisms. The silver nano-composites (AgNCs) were synthesized from the aqueous stem extract of Achyranthes aspera (AASE) using different concentration of aqueous silver nitrate (AgNO3). The synthesis was tracked by UV-vis spectrophotometer and particle size analyser (DLS). The evaluation of their larvicidal potential against early fourth instars of Ae. aegypti showed significant potency, the toxicity increasing with the concentration of silver nitrate. The 24, 48 and 72 h bioassays resulted in respective LC50 values of 26.693, 1.113 and 0.610 µg/mL (3 mM AASE-AgNO3) 9.119, 0.420 and 0.407 µg/mL (4 mM AASE-AgNO3) and that of 4.283, 0.3 and 0.248 µg/mL (5 mM AASE-AgNO3). Keeping in view the significantly high larvicidal efficiency at lower concentration of silver nitrate, the 4 mM nano-composites were selected over 5 mM composites for further biophysical characterization carried out by X-ray Diffraction (XRD), Fourier transform infrared spectrometer (FTIR), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) spectroscopy and Transmission electron microscopy (TEM). SEM and TEM confirmed the synthesis of spherical poly-dispersed AgNCs with average size ranging from 1-30 nm. Characterization through XRD showed the crystalline face-centered-cubic (fcc) structure of AgNCs with the highest intense peak obtained at 2θ value of 31.82°. FT-IR data suggests complex nature of AgNCs showing clearly defined peaks in different ranges. The present investigations recommend AgNCs of A. aspera stems as a low-cost and eco-friendly alternative to chemical insecticides for mosquito control.

Assessment of Achyranthes aspera induced toxicity and molecular analysis of RAPD-PCR profiles of larval genomic DNA of Aedes aegypti L. (Diptera: Culicidae).

Current studies investigated the anti-mosquito potential of Achyranthes aspera against the dengue vector, Aedes aegypti. The stems and leaves of A. aspera were extracted in hexane and evaluated for their toxicity against early fourth instars of A. aegypti. The larvicidal efficacy of the extract was validated as per WHO protocol. The mortality counts were made after 24 h and LC values were calculated at different levels. The adverse impact of extracts was also explored on the larval genomic DNA. The larvae were exposed to extracts at LC50 levels and the alterations in g-DNA was evaluated through RAPD-PCR technique using three random primers; MA-09, MA-12 and MA-26. Our investigations ascertained the larvicidal efficacy of both the leaf and stem extracts of A. aspera resulting in respective LC50 values of 0.068 and 0.082 mg/mL. The extracts also caused variable genotoxic effects with significant changes in the RAPD profiles. The results showed appreciable modifications in larval g-DNA with loss of certain bands and gain of unique bands with 82.35% DNA polymorphism. These alterations suggest the probable DNA damage and mutations in the larval g-DNA caused by certain phytocomponents which could be the possible reason of larval mortality. Our studies evidenced the anti-mosquito potential of A. aspera extracts against A. aegypti causing appreciable larval mortality and significant changes in g-DNA. The A. aspera extracts are suggested as efficient and eco-friendly control agent against A. aegypti, yet further investigations are needed to identify the bioactive constituent and ascertain its effectiveness in the field conditions.

Evaluation of the Larvicidal Efficacy of Five Indigenous Weeds against an Indian Strain of Dengue Vector, Aedes aegypti L. (Diptera: Culicidae).

Background and Objectives. Aedes aegypti, dengue fever mosquito, is primarily associated with the transmission of dengue and chikungunya in tropical and subtropical regions of the world. The present investigations were carried out to assess the larvicidal efficiency of five indigenous weeds against Ae. aegypti. Methods. The 1,000 ppm hexane and ethanol extracts prepared from the leaves and stem of five plants (Achyranthes aspera, Cassia occidentalis, Catharanthus roseus, Lantana camara, and Xanthium strumarium) were screened for their larvicidal activity against early fourth instars of dengue vector. The extracts which could cause 80-100% mortality were further investigated for their efficacy. Results. The preliminary screening established the efficacy of hexane extracts as compared to the ethanol extracts. Further investigations revealed the highest larvicidal potential of A. aspera extracts exhibiting LC50 value of 82.555 ppm and 68.133 ppm, respectively. Further, their leaf extracts showed 5-85.9% higher larvicidal activity and stem extracts exhibited 0.23- to 0.85-fold more efficiency than the other four extracts. Conclusion. The present investigations suggest the possible use of A. aspera as an ideal ecofriendly, larvicidal agent for the control of dengue vector, Ae. aegypti. Future studies are, however, required to explore and identify the bioactive component involved and its mode of action.

Minimal access therapy in pediatric pulmonary hydatid cysts.

Hydatid cysts occur commonly in lungs in the pediatric age group. Though medical management has been tried, definitive management of the condition is essentially surgical. Use of video-assisted thoracic surgery (VATS) has been rarely employed for the management of pulmonary hydatid cysts. We present a 10-year-old boy with pulmonary hydatid cysts treated with VATS-assisted minithoracotomy with hydatid cyst enucleation and capitonnage. The patient developed a lung abscess postoperatively and had to undergo lobectomy. The surgical management of pulmonary hydatid cysts is discussed here. The role of minimal access therapy for pulmonary hydatid cysts is highlighted.

Rabson-Mendenhall syndrome.

Rabson-Mendenhall syndrome is characterized by growth retardation, dysmorphisms, lack of subcutaneous fat, acanthosis nigricans, enlarged genitalia, hirsutism, premature and dysplastic dentition, coarse facial features, paradoxical fasting hypoglycemia and post-prandial hyperglycemia, extreme hyperinsulinemia and pineal hyperplasia. We describe a six-month-old female child with physical features suggestive of the Rabson-Mendenhall syndrome. The child also had medullary nephrocalcinosis.