Bio-fabrication of zinc oxide nanoparticles using leaf extract of Parthenium hysterophorus L. and its size-dependent antifungal activity against plant fungal pathogens.

Mosquitoes (Diptera: Culicidae) are a huge threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. Culicidae control is of crucial importance. Mosquito eggs, larvae, and pupae are usually targeted using organophosphates, insect growth regulators, and microbial agents. Indoor residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have negative effects on human health and the environment, and induce resistance in a number of species. Eco-friendly tools have been recently implemented against mosquito vectors, including botanical insecticides. The majority of researches focused on larvicides (745 SCOPUS results, July 2015) and adult repellents (434 SCOPUS results), while limited efforts were conducted to identify effective ovicides of botanical origin (59 SCOPUS results). Here, I review current knowledge on the effectiveness of plant-borne ovicides against major mosquito vectors of medical and veterinary importance. The majority of researches focused on the toxicity of crude extracts, their fractions, or essential oils against three important mosquito vectors, Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. As a general trend, C. quinquefasciatus eggs were the most resistant to botanical ovicides. Five studies proposed selected compounds from plant extracts and essential oils as ovicides effective at few parts per million. However, no efforts were conducted to shed light on possible mechanisms underlying the toxicity of plant-borne ovicides. In the final section, a number of hot issues needing further research and cooperation among parasitologists, entomologists, and researchers working in natural product chemistry are outlined.

Plant-borne ovicides in the fight against mosquito vectors of medical and veterinary importance: a systematic review

Make more knowledge even in less time every day. You may not always spend your time and money to go abroad and get the experience and knowledge by yourself. Reading is a good alternative to do in getting this desirable knowledge and experience. You may gain many things from experiencing directly, but of course it will spend much money. So here, by reading chinese herbal medicine, you can take more advantages with limited budget.

Chinese herbal medicine

This review aims to describe essential oils and their constituent compounds that exhibit bioactivity against Aedes aegypti L (Diptera: Culicidae) larvae, the immature stage of the primary vector of dengue This review is based on original articles obtained by searching on major databases Our literature review revealed that 361 essential oils from 269 plant species have been tested for their larvicidal activity More than 60 % of these essential oils were considered active (LC50<100 mg/L), and the majority of these active oils were derived from species belonging to Myrtaceae, Lamiaceae, and Rutaceae The most active essential oils exhibited effective concentrations comparable with the dosage recommended for the use of temephos in container breeding Approximately 27 % of the plants studied for their larvicidal activity against A aegypti were collected in Brazil Essential oils rich in phenylpropanoids, oxygenated sesquiterpenes, and monoterpene hydrocarbons were found to be the most active When the isolates were tested, phenylpropanoids and monoterpene hydrocarbons were the most active compound classes We describe the plant parts used and the major constituents of the essential oils In addition, we discuss factors affecting the activity (such as plant parts, age of the plant, chemotypes, larval source, and methods used), structure-activity relationships, and mechanisms of action of the essential oils and their compounds Essential oils have been widely investigated and show high larvicidal activity against A aegypti This review reveals that the essential oils are effective alternatives for the production of larvicides, which can be used in vector-borne disease control programmes

Essential oils and their compounds as Aedes aegypti L. (Diptera: Culicidae) larvicides: review

Larvicides play a vital role in controlling mosquitoes in their breeding sites. The present study was carried out to establish the larvicidal activities of mycosynthesized silver nanoparticles (AgNPs) against vectors: Aedes aegypti and Anopheles stephensi responsible for diseases of public health importance. The AgNPs synthesized by filamentous fungus Cochliobolus lunatus, characterized by UV–Vis spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The characterization studies confirmed the spherical shape and size (3–21 nm) of silver nanoparticles. The efficacy of mycosynthesized AgNPs at all the tested concentrations (10, 5, 2.5, 1.25, 0.625, and 0.3125 ppm) against second, third, and fourth instar larvae of A. aegypti (LC50 1.29, 1.48, and 1.58; LC90 3.08, 3.33, and 3.41 ppm) and against A. stephensi (LC50 1.17, 1.30, and 1.41; LC90 2.99, 3.13, and 3.29 ppm) were observed, respectively. The mortality rates were positively correlated with the concentration of AgNPs. Significant (P < 0.05) changes in the larval mortality was also recorded between the period of exposure against fourth instar larvae of A. aegypti and A. stephensi. The possible larvicidal activity may be due to penetration of nanoparticles through membrane. Toxicity studies carried out against non-target fish species Poecilia reticulata, the most common organism in the habitats of A. aegypti and A. stephensi showed no toxicity at LC50 and LC90 doses of the AgNPs. This is the first report on mosquito larvicidal activity of mycosynthesized nanoparticles. Thus, the use of fungus C. lunatus to synthesize silver nanoparticles is a rapid, eco-friendly, and a single-step approach and the AgNps formed can be potential mosquito larvicidal agents.

Larvicidal potential of silver nanoparticles synthesized using fungus Cochliobolus lunatus against Aedes aegypti (Linnaeus, 1762) and Anopheles stephensi Liston (Diptera; Culicidae)

Objective
To assess the larvicidal and repellent potential of the essential oil extracted from the leaves of peppermint plant, Mentha piperita (M. piperita) against the larval and adult stages of Aedes aegypti (Ae. Aegypti).

Bioefficacy of Mentha piperita essential oil against dengue fever mosquito 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.

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

Objective To assess the larvicidal and irritant activities of the hexane extracts of leaves of Citrus sinensis (C. sinensis) against the early fourth instars and female adults of Aedes aegypti (Ae. aegypti) Methods The larvicidal potential of the prepared leaf extract was evaluated against early fourth instar larvae of Ae. aegypti using WHO protocol. The mortality counts were made after 24 h and LC50 and LC90 values were calculated. The efficacy of extract as mosquito irritant was assessed by contact irritancy assays. Extract-impregnated paper was placed on a glass plate over which a perspex funnel with a hole on the top was kept inverted. Single female adult, 3-day old unfed/blood-fed, was released inside the funnel. After 3 min of acclimatization time, the time taken for the first take-off and total number of flights undertaken during 15 min were scored Results The citrus leaf extracts from hexane possessed moderate larvicidal efficiency against dengue vector. The bioassays resulted in an LC50 and LC90 value of 446.84 and 1 370.96 ppm, respectively after 24 h of exposure. However, the extracts were proved to be remarkable irritant against adults Ae. aegypti, more pronounced effects being observed on blood-fed females than unfed females. The extract-impregnated paper was thus proved to be 7-11 times more irritable as compared with the control paper. Conclusions The hexane extracts from C. sinensis leaves are proved to be reasonably larvicidal but remarkably irritant against dengue vector. Further studies are needed to identify the possible role of extract as adulticide, oviposition deterrent and ovicidal agent. The isolation of active ingredient from the extract could help in formulating strategies for mosquito control.

Larvicidal and irritant activities of hexane leaf extracts of Citrus sinensis against dengue vector Aedes aegypti L.

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% (LC50) 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% (LC90) values were 0.605, 0.758, and 0.801 ppm, respectively. Whereas against third instar larvae, the LC50 values recorded with three extracts were 0.022, 0.015, and 0.016 ppm and the LC90 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.

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)

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.

Radhika Warikoo

Papers

Bioefficacy of Mentha piperita essential oil against dengue fever mosquito Aedes aegypti L

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

Larvicidal and irritant activities of hexane leaf extracts of Citrus sinensis against dengue vector Aedes aegypti L.

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)

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