Objective:To isolate the larvicidal component from the fruits of Piper longum（P.longum） against the filariasis vector,Culex quinquefasciatus（C.quinquefasciatus）.Methods:Pulverized fruits of P.longum were subjected...Objective:To isolate the larvicidal component from the fruits of Piper longum（P.longum） against the filariasis vector,Culex quinquefasciatus（C.quinquefasciatus）.Methods:Pulverized fruits of P.longum were subjected to soxhlet extraction using series of organic solvents of increasing polarity.All the solvent extracts were verified for their larvicidal efficacy against 4th instar larvae of C.quinquefasciatus employing standard WHO procedure.Bioassayguided fractionation through column chromatography lead to the isolation of a bioactive amide, pipyahyine from the petroleum ether extract.Results:Petroleum ether extract was found to be the most active fraction among all the extracts tested with LC<sub>50</sub> and LC<sub>90</sub> being 1.03 and 2.04 ppm respectively.Whereas,pipyahyine,an isolated component of the same fraction was found to be even more effective than the parent extract in terms of LC<sub>50</sub> being 0.58 and 1.88 ppm respectively. Conclusions:From the results,it is evident that P.longum can be considered as a powerful arsenal for the control of mosquito population.展开更多
Objective:To evaluate larvicidal,pupicidal and oviposition deterrent activities of four plant essential oils from Alpinia galanga(L.)Willd rhizome,Anethum graveolens L.(An.graveolens)fruit,Foeniculum vulgare Mill.frui...Objective:To evaluate larvicidal,pupicidal and oviposition deterrent activities of four plant essential oils from Alpinia galanga(L.)Willd rhizome,Anethum graveolens L.(An.graveolens)fruit,Foeniculum vulgare Mill.fruit,and Pimpinella anisum L.fruit against Aedes aegypti(Ae.aegypti).Methods:Four essential oils at 1%,5%and 10%concentrations were assessed for insecticidal activity against larvae and pupae of Ae.aegypti,following the procedure of a dipping method assay.Oviposition deterrent activity of four essential oils was evaluated on gravid female of Ae.aegypti by a dual-choice oviposition bioassay.Results:The results revealed that An.graveolens oil provided the strongest larvicidal activity against Ae.aegypti among four tested plant essential oils with the highest mortality rate of 100%and LC_(50)value of-0.3%.From the pupicidal experiment,An.graveolens also showed the highest toxicity against Ae.aegypti pupae with the highest mortality rate of 100%at 72 h and LC_(50)value of2.9%.In addition,10%An.graveolens had an oviposition deterrent effect against Ae.aegypti with effective repellency of 100%and an oviposition activity index of-1.0.Conclusions:An.graveolens oil has a good potential as a larvicidal,pupicidal and oviposition deterrent agent for controlling Ae.aegypti.展开更多
Objective: To assess the chemical composition and mosquito larvicidal potentials of essential oil of wild chive(Allium schoenoprasum L.) against Anopheles stephensi.Methods: In the search for an environmentally safer ...Objective: To assess the chemical composition and mosquito larvicidal potentials of essential oil of wild chive(Allium schoenoprasum L.) against Anopheles stephensi.Methods: In the search for an environmentally safer alternative mosquitoes control, the larvicidal efficacy of essential oil obtained from the leaves of Allium schoenoprasum L. against Anopheles stephensi was determined. The composition of chive essential oil was analyzed by gas chromatography–mass spectrometry. Results: In toxicity assays, the essential oil demonstrated substantial larvicidal activity against larvae of Anopheles stephensi with LC_(50) and LC_(90) values of 2.60, and 7.31 ppm after 24 h of exposure, respectively. Gas chromatography–mass spectrometry analysis of chive essential oil identified 35 components representing more than 97.31% of the total essential oil. The main constituents were sulfur compounds, including diallyl trisulfide(13.72%), 2-ethyl[1,3]dithiane(8.93%), allyl methyl trisulfide(8.77%), and trimethylene trisulfide(6.64%), respectively. Conclusions: This study demonstrated that wild chive essential oil has a rich source of eco-friendly bioactive compounds for use as a mosquito larvicide. The main reason for its extraordinary properties may be related to the high percentage of sulfur compounds.展开更多
Dengue vector is responsible for millions of deaths every year and has caused disastrous impacts on health systems. The continuous use of chemical insecticides, such as carbamates, pyrethroids and organophosphates gen...Dengue vector is responsible for millions of deaths every year and has caused disastrous impacts on health systems. The continuous use of chemical insecticides, such as carbamates, pyrethroids and organophosphates generates resistant populations of the mosquito, therefore, new control methods must be investigated. The joint action of the population and guidelines for preventing the reproduction of the mosquito associated with the use of photoactivatable insecticides can be the alternative for the control of epidemiological outbreaks in affected regions. In this study, the photo-larvicidal activity of Photogem^（PG）, a derivative of hematoporphyrin, was investigated against 2nd-early 3rd instar of Aedes aegypti larvae （Diptera： Culicidae） under different lighting conditions （artificial lighting system and sunlight）. The dynamics of PG accumulation was characterized by CLSM （confocal laser scanning microscopy） and total time PG eliminationin solution was investigated by ultraviolet-visible spectrophotometry. The maximum photo-activity of PG was observed in 0.5 h under sunlight exposure which achieved 100% larval mortality. Fluorescence images showed a uniform distribution of PG along the digestive tract. PG remained stable in the sunlight for 48 h and in an artificial lighting system for longer periods, therefore, it can be used for the control ofAedes aegypti larvae as a new alternative to chemical insecticides. The method is considered environmentally friendly due to its rapid degradation in the presence of light. Further studies are required, so that the potential of the technique can be explored in real breeding places.展开更多
Objective:To formulate silver nanocomposites from Achyranthes aspera leaf extracts and evaluate its larvicidal activity against Aedes aegypti.Methods:The silver nanocomposites were synthesized from Achyranthes aspera ...Objective:To formulate silver nanocomposites from Achyranthes aspera leaf extracts and evaluate its larvicidal activity against Aedes aegypti.Methods:The silver nanocomposites were synthesized from Achyranthes aspera leaf extracts.The process was optimized and traced through UV-visible and photon correlation spectroscopy.The larvicidal potential of silver nanocomposites of Achyranthes aspera leaf extracts was assessed against the early fourth instars of Aedes aegypti and three non-target organisms.Furthermore,the most effective and eco-safe nanocomposite was characterized by different biophysical techniques including scanning electron microscopy(SEM),energy dispersive X-ray(EDX)spectroscopy,transmission electron microscopy(TEM),X-ray diffraction(XRD)and Fourier transform-infrared spectroscopy(FT-IR).Results:The formulated silver nanocomposites exhibited efficient larvicidal efficacy against Aedes aegypti.Bioassay with silver nanocomposites formulated using different Ag NO3 concentrations(3,4,and 5 m M)revealed respective LC50 values of 37.570,6.262 and 1.041μg/m L;5.819,1.412 and 0.489μg/m L;and 5.519,1.302 and 0.267μg/m L after 24,48 and 72 h.The silver nanocomposites with 4 m M Ag NO3 were selected for characterization.SEM and TEM analysis revealed spherical,poly-dispersed structure with varied diameters of 1-25 nm.The XRD analysis established the crystalline and face-centred-cubic structure of silver nanocomposites with the maximum peak at a 2θvalue of 37.42°.The EDX pattern showed the presence of Ag,O and C in the nanocomposites in their order of weight%.The FT-IR displayed visibly distinct peaks in different ranges demonstrating the intricacy of silver nanocomposites.In addition,the lethal concentrations of silver nanocomposites of Achyranthes aspera leaf extracts against Aedes aegypti larvae were non-toxic to non-target organisms including Gambusia affinis,Daphnia magna and Moina macrocopa.Conclusions:Silver nanocomposites synthesized with leaf extract of Achyranthes aspera provide a cost-effective and eco-safe alternative to conventional insecticides,and can be utilized as a potent mosquito nano-larvicide.展开更多
The issues of pyrethroid resistance and outdoor malaria parasite transmission have prompted the WHO to call for the development and adoption of viable alternative vector control methods.Larval source management is one...The issues of pyrethroid resistance and outdoor malaria parasite transmission have prompted the WHO to call for the development and adoption of viable alternative vector control methods.Larval source management is one of the core malaria vector interventions recommended by the Ministry of Health in many African countries,but it is rarely implemented due to concerns on its cost-effectiveness.New long-lasting microbial larvicide can be a promising cost-effective supplement to current vector control and elimination methods because microbial larvicide uses killing mechanisms different from pyrethroids and other chemical insecticides.It has been shown to be effective in reducing the overall vector abundance and thus both indoor and outdoor transmission.In our opinion,the long-lasting formulation can potentially reduce the cost of larvicide field application,and should be evaluated for its cost-effectiveness,resistance development,and impact on non-target organisms when integrating with other malaria vector control measures.In this opinion,we highlight that long-lasting microbial larvicide can be a potential cost-effective product that complements current front-line long-lasting insecticidal nets(LLINs)and indoor residual spraying(IRS)programs for malaria control and elimination.Microbial larviciding targets immature mosquitoes,reduces both indoor and outdoor transmission and is not affected by vector resistance to synthetic insecticides.This control method is a shift from the conventional LLINs and IRS programs that mainly target indoor-biting and resting adult mosquitoes.展开更多
In this paper,we analyze a stage structured mathematical model for the transmission of malaria and its control by killing mosquitoes in larvae(immature)stage.Both the Mosquito and human populations are divided into su...In this paper,we analyze a stage structured mathematical model for the transmission of malaria and its control by killing mosquitoes in larvae(immature)stage.Both the Mosquito and human populations are divided into susceptible and infective class.Sus-ceptible class of mosquito population is further divided into mature and immature.The model is analyzed by using stability theory of nonlinear ordinary differential equations.Basic reproduction ratio is derived which is found to be the decreasing function of maturation delay and larvicidal activity.In addition,it is observed that biting rate of mosquito,transmission efficiency of parasitic infection from infective human to mosquito and critical value of maturation delay are the key parameters determining the stability switch in the system.Numerical simulation is also carried out to confirm the analytical results obtained in the paper.展开更多
Background:Plants are known to produce a diverse group of natural metabolites with different biological activities.Centaurea ensiformis P.H.Davis,Origanum hypericifolium O.Schwartz&P.H.Davis,and Paeonia turcica Da...Background:Plants are known to produce a diverse group of natural metabolites with different biological activities.Centaurea ensiformis P.H.Davis,Origanum hypericifolium O.Schwartz&P.H.Davis,and Paeonia turcica Davis&Cullen are endemic plant species that grow on mountains in select regions in Türkiye and have been used in traditional Turkish medicine for various ailments.Methods:As first,we evaluated the larvicidal and antibiofilm activities of ethanol,ethyl acetate,acetone,and water extracts obtained from these plants.Antioxidant activities of the extracts were also investigated.Results:All tested extracts were effective at concentrations>25 ppm on Aedes aegypti larval mortality with the lethal concentration 50(LC_(50))values ranging between 32.82-48.35 ppm and LC90 between 46.26-63.2 ppm.O.hypericifolium was the most effective plant,ethanol extracts presented LC50 values of 32.82 ppm.Extracts demonstrated varying degrees of antibiofilm activity depending on the dose and bacterial species.Origanum hypericifolium extracts notably inhibited biofilms of Staphylococcus aureus(up to 98%inhibition),while P.turcica showed moderate efficacy against the same bacterial species.Pseudomonas aeruginosa biofilms displayed high resistance to all extracts.Conclusion:The results indicated that these endemic Turkish plants possess promising larvicidal and antibiofilm potential,particularly Origanum hypericifolium.Extracts analyzed by liquid chromatography-tandem mass spectrometry contained caffeic acid,myricetin,cinnamic acid,quercetin,gallic acid,epicatechin,and ascorbic acid.Further research should explore their potential applications in mosquito control and biofilm-related infections.展开更多
The identification of natural, plant-derived compounds with pesticidal properties is crucial for developing environmentally sustainable alternatives to synthetic pesticides. In this study, four major lignans—dihydroc...The identification of natural, plant-derived compounds with pesticidal properties is crucial for developing environmentally sustainable alternatives to synthetic pesticides. In this study, four major lignans—dihydroclusin, cubebin, clusin, and yatein—were isolated from the crude extract of Piper cubeba fruit. Phytotoxicity assays revealed herbicidal activity against Agrostis stolonifera, with dihydroclusin and clusin exhibiting the highest efficacy, inhibiting seed germination by 50% and showing IC50 values of 2.9 µM and 45 µM, respectively, against Lemna paucicostata. Additionally, all compounds, except dihydroclusin, demonstrated fungicidal activity against the strawberry anthracnose pathogen Colletotrichum fragariae. Moreover, only dihydroclusin exhibited larvicidal activity against Aedes aegypti, causing 96% mortality of mosquito larvae at the 100-ppm concentration tested. These findings highlight the broad-spectrum bioactivity of Piper cubeba lignans, suggesting their potential as alternative agents of synthetic pesticides for managing agricultural pests.展开更多
Objective:To evaluate the larvicidal and pupicidal potential of the methanolic extracts from Moringa oleifera(M.oleifera) plant seeds against malarial vector Anopheles stephensi(A.stephensi) mosquitoes at different co...Objective:To evaluate the larvicidal and pupicidal potential of the methanolic extracts from Moringa oleifera(M.oleifera) plant seeds against malarial vector Anopheles stephensi(A.stephensi) mosquitoes at different concentrations(20,40,60,80 and 100 ppm).Methods:M.oleifera was collected from the area of around Bharathiar University,Coimbatore.The dried plant materials were powdered by an electrical blender.From each sample,100 g of the plant material were extracted with 300 mL of methanol for 8 h in a Soxhlet apparatus.The extracts were evaporated to dryness in rotary vacuum evaporator to yield 122 mg and 110 mg of dark greenish material(residue) from Arcang amara and Ocimum basilicum,respectively.One gram of the each plant residue was dissolved separately in 100 mL of acetone(stock solution) from which different concentrations, i.e.,20,40,60,80 and 100 ppm were prepared.Results:Larvicidal activity of M.oleifera exhibited in the first to fourth instar larvae of the A.stephensi,and the LC_(50) and LC_(90) values were 57.79 ppm and 125.93 ppm for the first instar,63.90 ppm and 133.07 ppm for the second inslar,72.45 ppm and 139.82 ppm for the third instar,78.93 ppm and 143.20 ppm for the fourth instar,respectively. During the pupal stage the methanolic extract of M.oleifera showed that the LC_(50),and LC_(90) values were 67.77 ppm and 141.00 ppm,respectively.Conclusions:The present study indicates that the phytochemicals derived from M.oleifera seeds extracts are effective mosquito vector control agents and the plant extracts may be used for further integrated pest management programs.展开更多
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...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).Methods:The larvicidal potential of peppermint oil was evaluated against early fourth instar larvae of Ae.aegypti using WHO protocol.The mortality counts were made after 24 and 48 h,and LC_(50) and LC_(90) values were calculated.The efficacy of peppermint oil as mosquito repellent was assessed using the human-bait technique.The measured area of one arm of a human volunteer was applied with the oil and the other arm was applied with ethanol.The mosquito bites on both the arms were recorded for 3 min after every 15 min.The experiment continued for 3 h and the percent protection was calculated.Results:The essential oil extracted from M.piperita possessed excellent larvicidal efficiency against dengue vector. The bioassays showed an LC_(50) and LC_(90) value of 111.9 and 295.18 ppm,respectively after 24 h of exposure.The toxicity of the oil increased 11.8%when the larvae were exposed to the oil for 48 h.The remarkable repellent properties of M.piperita essential oil were established against adults Ae.aegypti.The application of oil resulted in 100%protection till 150 min.After next 30 min, only 1-2 bites were recorded as compared with 8-9 bites on the control arm.Conclusions:The peppermint essential oil is proved to be efficient larvicide and repellent against dengue vector. Further studies are needed to identify the possible role of oil as adulticide,oviposilion deterrent and ovicidal agent.The isolation of active ingredient from the oil could help in formulating strategies for mosquito control.展开更多
Objective:To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris(P.sylvestris)and Syzygium aromatkum(S.aromaticum)against Aedes aegypti(A.aegypti)an...Objective:To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris(P.sylvestris)and Syzygium aromatkum(S.aromaticum)against Aedes aegypti(A.aegypti)and Culex quinquefasciatus(C.quinquefasciatus).Method:The chemical composition of the essential oils of both plants was determined using GCMS while the larvicidal bioassay was carried out using different concentrations of the oils against the larvae of A.aegypti and C.quinquefasciatus in accordance with the standard protocol.Results:The results as determined by GC-MS showed that oil of S.aromaticum has eugenol(80.5%)as its principal constituent while P.sylvestris has 3-Cyclohexene-1-methanol,.alpha.,.alpha.4-trimethyl(27.1%)as its dominant constituent.Both oils achieved over 85%larval mortality within24 h.The larvae of A.aegypti were more susceptible to the oils[LC_(50)(S.aromaticum)=92.56 mg/L,LC_(50)(P.sylvestris)=100.39 mg/L]than C.quinquefasciatus[LC_(50)(S.aromaticum)=124.42 mg/L;LC_(50)(P.sylvestris)=128.00 mg/L].S.aromaticum oil was more toxic to the mosquito larvae than oil of P.sylvatris but the difference in lethal concentrations was insignificant(P>0.05).Condusioii:The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control.展开更多
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 lar...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.aegypli using WHO protocol.The mortality counts were made after 24 h and LC_(50)and LG_(50)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 LC_(50)and LC_(90)value of 446.84 and 1370.96 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.展开更多
Objective:To evaluate aqueous and ethanol extract of Cassia didymobotrya leaves against immature stages of Culex quinquefasciatus.Methods:The mortality rate of immature mosquitoes was tested in wide and narrow range c...Objective:To evaluate aqueous and ethanol extract of Cassia didymobotrya leaves against immature stages of Culex quinquefasciatus.Methods:The mortality rate of immature mosquitoes was tested in wide and narrow range concentration of the plant extract based on WHO standard protocol.The wide range concentration tested in the present study was 10 000,1 000,100,10 and1 mg/L and narrow range concentration was 50,100,150,200 and 250 mg/L.Results:2nd instar larvae exposed to 100 mg/L and above concentration of ethanol extract showed 100%mortality.Remaining stages such as 3rd,4th and pupa,100%mortality was observed at 1 000 mg/L and above concentration after 24 h exposure period.In aqueous extract all the stages 100%mortality was recorded at 1000 mg/L and above concentration.In narrow range concentration 2nd instar larvae 100%mortality was observed at 150 mg/L and above concentration of ethanol extract.The remaining stages 100%mortality was recorded at 250 mg/L.In aqueous extract all the tested immature stages 100%mortality was observed at 250 mg/L concentration after 24 h exposure period.The results clearly indicate that the rale of mortality was based dose of the plant extract and stage of the mosquitoes.Conclusions:From this study it is confirmed and concluded that Cassia didymobotrya is having active principle which is responsible for controlling Culex quinquefasciatus.The isolation of biouctive molecules and development of simple formulation technique is important for large scale implementation.展开更多
Objective:To determine phytochemistry and larvicidal activity of Eucalyptus eamaldulensis against Anopheles stephensi.Methods:The chemical compositions of the leaf essential oils were analyzed using gas chromatography...Objective:To determine phytochemistry and larvicidal activity of Eucalyptus eamaldulensis against Anopheles stephensi.Methods:The chemical compositions of the leaf essential oils were analyzed using gas chromatography/mass spectrometry（GC/MS）.The larvicidal activity of essential oils and extract of leaf were tested against 4th instar larvae of laboratory-reared Anopheles stephensi.Results:GC/MS analyses identified the presence of 28 compounds corresponding to 99.60%of the total oil.The main constituents in the leaf essential oil were 1,8-cineole（69.46%）,γ-Terpinene（15.10%）,α-Pinene（5.47%） and Globulol（2%）.The leaf extract and volatile oil exerted significant larvicidal activity with LC<sub>50</sub> values of 89.85 and 397.75 ppm,respectively.Clear dose-response relationships were established with the highest dose of 320 ppm essential oil extract resulted almost 100%mortality in the population.Conclusions:The larvicidal properties suggest that the essential oil of plant is a potential source of valuable larvicidal compounds against malaria vector and can be used as an alternative to synthetic insecticides.展开更多
Objective:To elucidate the larvicidal potency of neem, chinaberry and Bacillus thuringiensis israelensis(Bti) to larvae of Anopheles arabiensis under semi-field condition and adult susceptibility/resistance to the con...Objective:To elucidate the larvicidal potency of neem, chinaberry and Bacillus thuringiensis israelensis(Bti) to larvae of Anopheles arabiensis under semi-field condition and adult susceptibility/resistance to the conventionally used insecticides in Tolay,Southwestern Ethiopia.Methods: Wild collected 3rd and 4th stage larvae were exposed to neem, and chinaberry seed powder dissolved in water and Bti in artificial containers at three treatment levels:0.2, 0.1 and 0.05 g/m^2 and controls were free of treatments. Larval and pupal mortalities were monitored daily and residual activities were determined. The experiments were replicated three times. The World Health Organization tube test for all classes of insecticides was conducted on adult Anopheles arabiensis reared from field collected larvae and pupae. Data were analyzed using STATA software version 11.Results: In the first application, neem powder caused 88.9%, 87.9% and 79.4% larval and pupal mortality at 0.2, 0.1 and 0.05 g/m^2 after 4.3, 6.0 and 5.7 days, respectively. The corresponding killing effect of chinaberry was 80.3%, 62.1% and 30.3% after 7.0, 7.7 and 8.3days respectively. Bti at all treatments killed 100% after 24 h except 2.7 days for 0.05 g/m^2.Adult mosquitoes were susceptible only for fenitrothion and pirimiphos-methyl with 100%mortality while resistant to deltamethrin, alpha-cypermethrin, etofenprox and dichlorodiphenyl-tricgloroethane with only 9.0%, 3.0%, 5.1% and 2.0% mortalities respectively.Conclusions: Neem, chinaberry and Bti showed potent larvicidal and pupicidal activities. However, in the area, high level of mosquito resistance to pyrethroids and dichlorodiphenyl-tricgloroethane was seen which will pose serious challenge to vector control in the future. Therefore, using integrated approach including these botanical larvicides is warranted to manage insecticide resistance.展开更多
Objective: To evaluate adulticidal, larvicidal and oviposition deterrent response of the essential oil from dried Zanthoxylum limonella(Z. limonella) fruit against Aedes aegypti(Ae. aegypti) and Culex quinquefasciatus...Objective: To evaluate adulticidal, larvicidal and oviposition deterrent response of the essential oil from dried Zanthoxylum limonella(Z. limonella) fruit against Aedes aegypti(Ae. aegypti) and Culex quinquefasciatus(Cx. quinquefasciatus).Methods: Z. limonella oil was tested by biological assays at 1%, 5% and 10% concentrations in ethanol. Adulticidal efficacy was tested against the 2–3 day old adult females. Larvicidal activity was tested against immature stage of mosquitoes. Oviposition deterrence of the oil was evaluated on gravid females.Results: The adult mortality was observed after 24 h with the LC50 of 6.0% for Ae.aegypti, and 5.7% for Cx. quinquefasciatus. Larvicidal bioassay was carried out with the 10% Z. limonella oil against immature stages of Ae. aegypti and Cx. quinquefasciatus,which caused 100% mortality after 12 h and 24 h. In the larvicidal experiment,Z. limonella showed effective result at 1%, 5% and 10% concentrations with the values of LT50 Ae. aegypti = 9.78, 5.61, 0.24 h for larvae and LT50= 64.08, 21.23 h for pupae;Cx. quinquefasciatus had LT50= 28.46, 20.25, 1.01 h for larvae and LT50= 67.52, 27.96,4.11 h for pupae, respectively. Oviposition deterrence of the oil was evaluated on gravid females. In the study, 10% Z. limonella showed 100% repellency for Ae. aegypti and99.53% for Cx. quinquefasciatus. Likewise, oviposition activity indexes of these oil concentrations were all negative values ranging from–0.89 to-1.00 for Ae. aegypti and–0.64 to–0.99 for Cx. quinquefasciatus. The oviposition activity indexes values revealed that Z. limonella oil has deterrent effect, and it caused a remarkable negative response resulting in very few eggs.Conclusions: This result indicates that Z. limonella oil can be used as an effective adulticide, larvicide and oviposition deterrent against Ae. aegypti and Cx. quinquefasciatus.展开更多
Objective: To investigate the larvicidal activity of Syzygium guineense(Myrtaceae)(S. guineense), Monodora myristica and Zanthoxylum heitzii(Rutaceae)(Z. heitzii) extracts against Aedes albopictus(Ae. albopictus).Meth...Objective: To investigate the larvicidal activity of Syzygium guineense(Myrtaceae)(S. guineense), Monodora myristica and Zanthoxylum heitzii(Rutaceae)(Z. heitzii) extracts against Aedes albopictus(Ae. albopictus).Methods: The larvicidal activity of the hydro-ethanolic extracts from these plant species was assessed at three different concentrations(50, 100 and 200 mg/L) on first-instar of Ae. albopictus larvae in comparison with untreated controls. Mortality rate was recorded daily for a period of 12 days. The values of LC_(50) and lethal time killing 50% of the tested individuals(LT_(50)) were calculated using the log-probit analysis.Results: The root extract of S. guineense exhibited the best activity with 100% mortality after 8 days of treatment at 200 mg/L, followed by the fruit extract of Z. heitzii with83.33% mortality at the same concentration. Nonetheless, larvae were most susceptible to the fruit extract of Z. heitzii both in terms of LC_(50)(39.89 mg/L) and LT_(50)(145.68 h). A statistically significant difference between the control and the group treated at 200 mg/L was noticed in all the extracts.Conclusions: The present study shows that the hydro-ethanolic extracts of S. guineense,Monodora myristica and Z. heitzii tested have significant larvicidal activity. These preliminary results are of great interest and some of these plant species can be proposed for the formulation of new bioinsecticides to control Ae. albopictus populations.展开更多
Objective:To establish the larvicidal activities,if any of solvent extracts of Rauvolfia serpentina (R.serpentina) L.seeds against Culex quinquefasciatus(Cx.quinquefasciatus) Say.1823 as target species.Methods:Seeds o...Objective:To establish the larvicidal activities,if any of solvent extracts of Rauvolfia serpentina (R.serpentina) L.seeds against Culex quinquefasciatus(Cx.quinquefasciatus) Say.1823 as target species.Methods:Seeds of R.serpentina were extracted with five solvents graded according to the polarity[viz.petroleum ether.benzene,ethyl acetate,acetone and absolute alcohol] continuing one after another with the same seeds.Results:Mortality rate with petroleum ether extract was significantly higher than other extracts.The mortality rates of late 3rd instar larvae wore 50.33±5.51.10.00±1.00.0.00±0.00.21.33±1.53 and 0.00±0.00 in 100 ppm concentration of petroleum ether,benzene,ethyl acetate,acetone and absolute alcohol respectively,after 24 h of exposure period.Conclusions:Results of this study show that petroleum ether extract of R. serpentina seed may be considered as a potent source of mosquito larvicidal agent.展开更多
Objective:To investigate the larvicidal activities of crude and chlor of orm:methanol(1:1 v/ v) extracts of some common spices(Cuminum cyminum,Allium sativum,Zingiber offinale, Curcuma longa) and vegetable waste(Solan...Objective:To investigate the larvicidal activities of crude and chlor of orm:methanol(1:1 v/ v) extracts of some common spices(Cuminum cyminum,Allium sativum,Zingiber offinale, Curcuma longa) and vegetable waste(Solanum tuberosum germinated tuber) against Anopheles stephensi and Culex quinquefasciatus mosquito larvae.Methods:Larval mortality of above mosquito species were observed after 24,48 and 72 h of exposure to five concentrations of aqueous extract(0.1%,0.2%,0.3%,0.4%and 0.5%) and four concentrations(25,50,75 ppm) of chlor of orm:methanol(1:1 v/v) extract.The lethal concentration of individual spices or vegetable waste was determined by log-probit analysis(at 95%confidence level) and effect of crude and chlor of orm:methanol(1:1 v/v) extracts were recorded on non target organisms.Results: Relative mortality rate of both larval mosquito species were recorded in the following sequences: Cuminum cyminum】 Allium sativum】Zingiber offinale,Curcuma longa 】 Solanum tuberosum germinated tuber for crude extract,and efficacy of chlor of orm:methanol(1:1 v/v) extract were as follows:Curcuma longa 】 Zingiber offinale 】 Solanum tuberosum germinated tuber 】 Cuminum cyminum】 Allium sativum.Conclusions:Crude and chlor of orm:methanol(1:1 v/v) extract of Cuminum cyminum,Allium sativum,Zingiber offinale,Curcuma longa and Solanum tuberosum germinated tuber can be recommended effectively in mosquito control programmes at very low concentrations.No mortality and other abnormalities were noticed on non target organisms and further studies are needed to investigate the chemical structure of active principal which are responsible for larvicidal activity.展开更多
基金Department of Science and Technology,New Delhi,India for providing financial assistance under women scientist scheme-B
文摘Objective:To isolate the larvicidal component from the fruits of Piper longum（P.longum） against the filariasis vector,Culex quinquefasciatus（C.quinquefasciatus）.Methods:Pulverized fruits of P.longum were subjected to soxhlet extraction using series of organic solvents of increasing polarity.All the solvent extracts were verified for their larvicidal efficacy against 4th instar larvae of C.quinquefasciatus employing standard WHO procedure.Bioassayguided fractionation through column chromatography lead to the isolation of a bioactive amide, pipyahyine from the petroleum ether extract.Results:Petroleum ether extract was found to be the most active fraction among all the extracts tested with LC<sub>50</sub> and LC<sub>90</sub> being 1.03 and 2.04 ppm respectively.Whereas,pipyahyine,an isolated component of the same fraction was found to be even more effective than the parent extract in terms of LC<sub>50</sub> being 0.58 and 1.88 ppm respectively. Conclusions:From the results,it is evident that P.longum can be considered as a powerful arsenal for the control of mosquito population.
基金sponsored in part by the National Research Council of Thailand,(Grant no.GRAD6006 KMITL)by the Faculty of Agricultural Technology,King Mongkut's Institute of Technology Ladkrabang(KMITL)(Grant no.01-04-001)
文摘Objective:To evaluate larvicidal,pupicidal and oviposition deterrent activities of four plant essential oils from Alpinia galanga(L.)Willd rhizome,Anethum graveolens L.(An.graveolens)fruit,Foeniculum vulgare Mill.fruit,and Pimpinella anisum L.fruit against Aedes aegypti(Ae.aegypti).Methods:Four essential oils at 1%,5%and 10%concentrations were assessed for insecticidal activity against larvae and pupae of Ae.aegypti,following the procedure of a dipping method assay.Oviposition deterrent activity of four essential oils was evaluated on gravid female of Ae.aegypti by a dual-choice oviposition bioassay.Results:The results revealed that An.graveolens oil provided the strongest larvicidal activity against Ae.aegypti among four tested plant essential oils with the highest mortality rate of 100%and LC_(50)value of-0.3%.From the pupicidal experiment,An.graveolens also showed the highest toxicity against Ae.aegypti pupae with the highest mortality rate of 100%at 72 h and LC_(50)value of2.9%.In addition,10%An.graveolens had an oviposition deterrent effect against Ae.aegypti with effective repellency of 100%and an oviposition activity index of-1.0.Conclusions:An.graveolens oil has a good potential as a larvicidal,pupicidal and oviposition deterrent agent for controlling Ae.aegypti.
文摘Objective: To assess the chemical composition and mosquito larvicidal potentials of essential oil of wild chive(Allium schoenoprasum L.) against Anopheles stephensi.Methods: In the search for an environmentally safer alternative mosquitoes control, the larvicidal efficacy of essential oil obtained from the leaves of Allium schoenoprasum L. against Anopheles stephensi was determined. The composition of chive essential oil was analyzed by gas chromatography–mass spectrometry. Results: In toxicity assays, the essential oil demonstrated substantial larvicidal activity against larvae of Anopheles stephensi with LC_(50) and LC_(90) values of 2.60, and 7.31 ppm after 24 h of exposure, respectively. Gas chromatography–mass spectrometry analysis of chive essential oil identified 35 components representing more than 97.31% of the total essential oil. The main constituents were sulfur compounds, including diallyl trisulfide(13.72%), 2-ethyl[1,3]dithiane(8.93%), allyl methyl trisulfide(8.77%), and trimethylene trisulfide(6.64%), respectively. Conclusions: This study demonstrated that wild chive essential oil has a rich source of eco-friendly bioactive compounds for use as a mosquito larvicide. The main reason for its extraordinary properties may be related to the high percentage of sulfur compounds.
文摘Dengue vector is responsible for millions of deaths every year and has caused disastrous impacts on health systems. The continuous use of chemical insecticides, such as carbamates, pyrethroids and organophosphates generates resistant populations of the mosquito, therefore, new control methods must be investigated. The joint action of the population and guidelines for preventing the reproduction of the mosquito associated with the use of photoactivatable insecticides can be the alternative for the control of epidemiological outbreaks in affected regions. In this study, the photo-larvicidal activity of Photogem^（PG）, a derivative of hematoporphyrin, was investigated against 2nd-early 3rd instar of Aedes aegypti larvae （Diptera： Culicidae） under different lighting conditions （artificial lighting system and sunlight）. The dynamics of PG accumulation was characterized by CLSM （confocal laser scanning microscopy） and total time PG eliminationin solution was investigated by ultraviolet-visible spectrophotometry. The maximum photo-activity of PG was observed in 0.5 h under sunlight exposure which achieved 100% larval mortality. Fluorescence images showed a uniform distribution of PG along the digestive tract. PG remained stable in the sunlight for 48 h and in an artificial lighting system for longer periods, therefore, it can be used for the control ofAedes aegypti larvae as a new alternative to chemical insecticides. The method is considered environmentally friendly due to its rapid degradation in the presence of light. Further studies are required, so that the potential of the technique can be explored in real breeding places.
基金partly supported by the research grant from University Grant Commission,New Delhi(Award No.53583)partly from research contingency from Acharya Narendra Dev College,New Delhi.
文摘Objective:To formulate silver nanocomposites from Achyranthes aspera leaf extracts and evaluate its larvicidal activity against Aedes aegypti.Methods:The silver nanocomposites were synthesized from Achyranthes aspera leaf extracts.The process was optimized and traced through UV-visible and photon correlation spectroscopy.The larvicidal potential of silver nanocomposites of Achyranthes aspera leaf extracts was assessed against the early fourth instars of Aedes aegypti and three non-target organisms.Furthermore,the most effective and eco-safe nanocomposite was characterized by different biophysical techniques including scanning electron microscopy(SEM),energy dispersive X-ray(EDX)spectroscopy,transmission electron microscopy(TEM),X-ray diffraction(XRD)and Fourier transform-infrared spectroscopy(FT-IR).Results:The formulated silver nanocomposites exhibited efficient larvicidal efficacy against Aedes aegypti.Bioassay with silver nanocomposites formulated using different Ag NO3 concentrations(3,4,and 5 m M)revealed respective LC50 values of 37.570,6.262 and 1.041μg/m L;5.819,1.412 and 0.489μg/m L;and 5.519,1.302 and 0.267μg/m L after 24,48 and 72 h.The silver nanocomposites with 4 m M Ag NO3 were selected for characterization.SEM and TEM analysis revealed spherical,poly-dispersed structure with varied diameters of 1-25 nm.The XRD analysis established the crystalline and face-centred-cubic structure of silver nanocomposites with the maximum peak at a 2θvalue of 37.42°.The EDX pattern showed the presence of Ag,O and C in the nanocomposites in their order of weight%.The FT-IR displayed visibly distinct peaks in different ranges demonstrating the intricacy of silver nanocomposites.In addition,the lethal concentrations of silver nanocomposites of Achyranthes aspera leaf extracts against Aedes aegypti larvae were non-toxic to non-target organisms including Gambusia affinis,Daphnia magna and Moina macrocopa.Conclusions:Silver nanocomposites synthesized with leaf extract of Achyranthes aspera provide a cost-effective and eco-safe alternative to conventional insecticides,and can be utilized as a potent mosquito nano-larvicide.
基金This work was supported by the National Institutes of Health(R01 A1050243,U19 AI129326 and D43 TW001505).
文摘The issues of pyrethroid resistance and outdoor malaria parasite transmission have prompted the WHO to call for the development and adoption of viable alternative vector control methods.Larval source management is one of the core malaria vector interventions recommended by the Ministry of Health in many African countries,but it is rarely implemented due to concerns on its cost-effectiveness.New long-lasting microbial larvicide can be a promising cost-effective supplement to current vector control and elimination methods because microbial larvicide uses killing mechanisms different from pyrethroids and other chemical insecticides.It has been shown to be effective in reducing the overall vector abundance and thus both indoor and outdoor transmission.In our opinion,the long-lasting formulation can potentially reduce the cost of larvicide field application,and should be evaluated for its cost-effectiveness,resistance development,and impact on non-target organisms when integrating with other malaria vector control measures.In this opinion,we highlight that long-lasting microbial larvicide can be a potential cost-effective product that complements current front-line long-lasting insecticidal nets(LLINs)and indoor residual spraying(IRS)programs for malaria control and elimination.Microbial larviciding targets immature mosquitoes,reduces both indoor and outdoor transmission and is not affected by vector resistance to synthetic insecticides.This control method is a shift from the conventional LLINs and IRS programs that mainly target indoor-biting and resting adult mosquitoes.
文摘In this paper,we analyze a stage structured mathematical model for the transmission of malaria and its control by killing mosquitoes in larvae(immature)stage.Both the Mosquito and human populations are divided into susceptible and infective class.Sus-ceptible class of mosquito population is further divided into mature and immature.The model is analyzed by using stability theory of nonlinear ordinary differential equations.Basic reproduction ratio is derived which is found to be the decreasing function of maturation delay and larvicidal activity.In addition,it is observed that biting rate of mosquito,transmission efficiency of parasitic infection from infective human to mosquito and critical value of maturation delay are the key parameters determining the stability switch in the system.Numerical simulation is also carried out to confirm the analytical results obtained in the paper.
文摘Background:Plants are known to produce a diverse group of natural metabolites with different biological activities.Centaurea ensiformis P.H.Davis,Origanum hypericifolium O.Schwartz&P.H.Davis,and Paeonia turcica Davis&Cullen are endemic plant species that grow on mountains in select regions in Türkiye and have been used in traditional Turkish medicine for various ailments.Methods:As first,we evaluated the larvicidal and antibiofilm activities of ethanol,ethyl acetate,acetone,and water extracts obtained from these plants.Antioxidant activities of the extracts were also investigated.Results:All tested extracts were effective at concentrations>25 ppm on Aedes aegypti larval mortality with the lethal concentration 50(LC_(50))values ranging between 32.82-48.35 ppm and LC90 between 46.26-63.2 ppm.O.hypericifolium was the most effective plant,ethanol extracts presented LC50 values of 32.82 ppm.Extracts demonstrated varying degrees of antibiofilm activity depending on the dose and bacterial species.Origanum hypericifolium extracts notably inhibited biofilms of Staphylococcus aureus(up to 98%inhibition),while P.turcica showed moderate efficacy against the same bacterial species.Pseudomonas aeruginosa biofilms displayed high resistance to all extracts.Conclusion:The results indicated that these endemic Turkish plants possess promising larvicidal and antibiofilm potential,particularly Origanum hypericifolium.Extracts analyzed by liquid chromatography-tandem mass spectrometry contained caffeic acid,myricetin,cinnamic acid,quercetin,gallic acid,epicatechin,and ascorbic acid.Further research should explore their potential applications in mosquito control and biofilm-related infections.
文摘The identification of natural, plant-derived compounds with pesticidal properties is crucial for developing environmentally sustainable alternatives to synthetic pesticides. In this study, four major lignans—dihydroclusin, cubebin, clusin, and yatein—were isolated from the crude extract of Piper cubeba fruit. Phytotoxicity assays revealed herbicidal activity against Agrostis stolonifera, with dihydroclusin and clusin exhibiting the highest efficacy, inhibiting seed germination by 50% and showing IC50 values of 2.9 µM and 45 µM, respectively, against Lemna paucicostata. Additionally, all compounds, except dihydroclusin, demonstrated fungicidal activity against the strawberry anthracnose pathogen Colletotrichum fragariae. Moreover, only dihydroclusin exhibited larvicidal activity against Aedes aegypti, causing 96% mortality of mosquito larvae at the 100-ppm concentration tested. These findings highlight the broad-spectrum bioactivity of Piper cubeba lignans, suggesting their potential as alternative agents of synthetic pesticides for managing agricultural pests.
文摘Objective:To evaluate the larvicidal and pupicidal potential of the methanolic extracts from Moringa oleifera(M.oleifera) plant seeds against malarial vector Anopheles stephensi(A.stephensi) mosquitoes at different concentrations(20,40,60,80 and 100 ppm).Methods:M.oleifera was collected from the area of around Bharathiar University,Coimbatore.The dried plant materials were powdered by an electrical blender.From each sample,100 g of the plant material were extracted with 300 mL of methanol for 8 h in a Soxhlet apparatus.The extracts were evaporated to dryness in rotary vacuum evaporator to yield 122 mg and 110 mg of dark greenish material(residue) from Arcang amara and Ocimum basilicum,respectively.One gram of the each plant residue was dissolved separately in 100 mL of acetone(stock solution) from which different concentrations, i.e.,20,40,60,80 and 100 ppm were prepared.Results:Larvicidal activity of M.oleifera exhibited in the first to fourth instar larvae of the A.stephensi,and the LC_(50) and LC_(90) values were 57.79 ppm and 125.93 ppm for the first instar,63.90 ppm and 133.07 ppm for the second inslar,72.45 ppm and 139.82 ppm for the third instar,78.93 ppm and 143.20 ppm for the fourth instar,respectively. During the pupal stage the methanolic extract of M.oleifera showed that the LC_(50),and LC_(90) values were 67.77 ppm and 141.00 ppm,respectively.Conclusions:The present study indicates that the phytochemicals derived from M.oleifera seeds extracts are effective mosquito vector control agents and the plant extracts may be used for further integrated pest management programs.
文摘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).Methods:The larvicidal potential of peppermint oil was evaluated against early fourth instar larvae of Ae.aegypti using WHO protocol.The mortality counts were made after 24 and 48 h,and LC_(50) and LC_(90) values were calculated.The efficacy of peppermint oil as mosquito repellent was assessed using the human-bait technique.The measured area of one arm of a human volunteer was applied with the oil and the other arm was applied with ethanol.The mosquito bites on both the arms were recorded for 3 min after every 15 min.The experiment continued for 3 h and the percent protection was calculated.Results:The essential oil extracted from M.piperita possessed excellent larvicidal efficiency against dengue vector. The bioassays showed an LC_(50) and LC_(90) value of 111.9 and 295.18 ppm,respectively after 24 h of exposure.The toxicity of the oil increased 11.8%when the larvae were exposed to the oil for 48 h.The remarkable repellent properties of M.piperita essential oil were established against adults Ae.aegypti.The application of oil resulted in 100%protection till 150 min.After next 30 min, only 1-2 bites were recorded as compared with 8-9 bites on the control arm.Conclusions:The peppermint essential oil is proved to be efficient larvicide and repellent against dengue vector. Further studies are needed to identify the possible role of oil as adulticide,oviposilion deterrent and ovicidal agent.The isolation of active ingredient from the oil could help in formulating strategies for mosquito control.
基金Logistic support from the Management of Osun State University Osogbo through grant support number UNIOSUN/SET/010
文摘Objective:To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris(P.sylvestris)and Syzygium aromatkum(S.aromaticum)against Aedes aegypti(A.aegypti)and Culex quinquefasciatus(C.quinquefasciatus).Method:The chemical composition of the essential oils of both plants was determined using GCMS while the larvicidal bioassay was carried out using different concentrations of the oils against the larvae of A.aegypti and C.quinquefasciatus in accordance with the standard protocol.Results:The results as determined by GC-MS showed that oil of S.aromaticum has eugenol(80.5%)as its principal constituent while P.sylvestris has 3-Cyclohexene-1-methanol,.alpha.,.alpha.4-trimethyl(27.1%)as its dominant constituent.Both oils achieved over 85%larval mortality within24 h.The larvae of A.aegypti were more susceptible to the oils[LC_(50)(S.aromaticum)=92.56 mg/L,LC_(50)(P.sylvestris)=100.39 mg/L]than C.quinquefasciatus[LC_(50)(S.aromaticum)=124.42 mg/L;LC_(50)(P.sylvestris)=128.00 mg/L].S.aromaticum oil was more toxic to the mosquito larvae than oil of P.sylvatris but the difference in lethal concentrations was insignificant(P>0.05).Condusioii:The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control.
基金supported by University Grants Commission[grant No.F.35-74/2009(SR)]
文摘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.aegypli using WHO protocol.The mortality counts were made after 24 h and LC_(50)and LG_(50)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 LC_(50)and LC_(90)value of 446.84 and 1370.96 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.
基金Supported by University of Gondar(UOG/Budget/no.6215)
文摘Objective:To evaluate aqueous and ethanol extract of Cassia didymobotrya leaves against immature stages of Culex quinquefasciatus.Methods:The mortality rate of immature mosquitoes was tested in wide and narrow range concentration of the plant extract based on WHO standard protocol.The wide range concentration tested in the present study was 10 000,1 000,100,10 and1 mg/L and narrow range concentration was 50,100,150,200 and 250 mg/L.Results:2nd instar larvae exposed to 100 mg/L and above concentration of ethanol extract showed 100%mortality.Remaining stages such as 3rd,4th and pupa,100%mortality was observed at 1 000 mg/L and above concentration after 24 h exposure period.In aqueous extract all the stages 100%mortality was recorded at 1000 mg/L and above concentration.In narrow range concentration 2nd instar larvae 100%mortality was observed at 150 mg/L and above concentration of ethanol extract.The remaining stages 100%mortality was recorded at 250 mg/L.In aqueous extract all the tested immature stages 100%mortality was observed at 250 mg/L concentration after 24 h exposure period.The results clearly indicate that the rale of mortality was based dose of the plant extract and stage of the mosquitoes.Conclusions:From this study it is confirmed and concluded that Cassia didymobotrya is having active principle which is responsible for controlling Culex quinquefasciatus.The isolation of biouctive molecules and development of simple formulation technique is important for large scale implementation.
基金Supported by Centre of Ernriromental Research,TUMS,Iran. (grant No.88-01-46-661)
文摘Objective:To determine phytochemistry and larvicidal activity of Eucalyptus eamaldulensis against Anopheles stephensi.Methods:The chemical compositions of the leaf essential oils were analyzed using gas chromatography/mass spectrometry（GC/MS）.The larvicidal activity of essential oils and extract of leaf were tested against 4th instar larvae of laboratory-reared Anopheles stephensi.Results:GC/MS analyses identified the presence of 28 compounds corresponding to 99.60%of the total oil.The main constituents in the leaf essential oil were 1,8-cineole（69.46%）,γ-Terpinene（15.10%）,α-Pinene（5.47%） and Globulol（2%）.The leaf extract and volatile oil exerted significant larvicidal activity with LC<sub>50</sub> values of 89.85 and 397.75 ppm,respectively.Clear dose-response relationships were established with the highest dose of 320 ppm essential oil extract resulted almost 100%mortality in the population.Conclusions:The larvicidal properties suggest that the essential oil of plant is a potential source of valuable larvicidal compounds against malaria vector and can be used as an alternative to synthetic insecticides.
基金Supported by the International Center of Insect Physiology and Ecology(ICIPE) or Bio-vision Foundation Ethiopia(Grant No.BV-HH-03)
文摘Objective:To elucidate the larvicidal potency of neem, chinaberry and Bacillus thuringiensis israelensis(Bti) to larvae of Anopheles arabiensis under semi-field condition and adult susceptibility/resistance to the conventionally used insecticides in Tolay,Southwestern Ethiopia.Methods: Wild collected 3rd and 4th stage larvae were exposed to neem, and chinaberry seed powder dissolved in water and Bti in artificial containers at three treatment levels:0.2, 0.1 and 0.05 g/m^2 and controls were free of treatments. Larval and pupal mortalities were monitored daily and residual activities were determined. The experiments were replicated three times. The World Health Organization tube test for all classes of insecticides was conducted on adult Anopheles arabiensis reared from field collected larvae and pupae. Data were analyzed using STATA software version 11.Results: In the first application, neem powder caused 88.9%, 87.9% and 79.4% larval and pupal mortality at 0.2, 0.1 and 0.05 g/m^2 after 4.3, 6.0 and 5.7 days, respectively. The corresponding killing effect of chinaberry was 80.3%, 62.1% and 30.3% after 7.0, 7.7 and 8.3days respectively. Bti at all treatments killed 100% after 24 h except 2.7 days for 0.05 g/m^2.Adult mosquitoes were susceptible only for fenitrothion and pirimiphos-methyl with 100%mortality while resistant to deltamethrin, alpha-cypermethrin, etofenprox and dichlorodiphenyl-tricgloroethane with only 9.0%, 3.0%, 5.1% and 2.0% mortalities respectively.Conclusions: Neem, chinaberry and Bti showed potent larvicidal and pupicidal activities. However, in the area, high level of mosquito resistance to pyrethroids and dichlorodiphenyl-tricgloroethane was seen which will pose serious challenge to vector control in the future. Therefore, using integrated approach including these botanical larvicides is warranted to manage insecticide resistance.
基金supported by the Faculty of Agricultural Technology,King Mongkut's Institute of Technology Ladkrabang,Bangkok,Thailand(Grant No.2560-01-04-003)
文摘Objective: To evaluate adulticidal, larvicidal and oviposition deterrent response of the essential oil from dried Zanthoxylum limonella(Z. limonella) fruit against Aedes aegypti(Ae. aegypti) and Culex quinquefasciatus(Cx. quinquefasciatus).Methods: Z. limonella oil was tested by biological assays at 1%, 5% and 10% concentrations in ethanol. Adulticidal efficacy was tested against the 2–3 day old adult females. Larvicidal activity was tested against immature stage of mosquitoes. Oviposition deterrence of the oil was evaluated on gravid females.Results: The adult mortality was observed after 24 h with the LC50 of 6.0% for Ae.aegypti, and 5.7% for Cx. quinquefasciatus. Larvicidal bioassay was carried out with the 10% Z. limonella oil against immature stages of Ae. aegypti and Cx. quinquefasciatus,which caused 100% mortality after 12 h and 24 h. In the larvicidal experiment,Z. limonella showed effective result at 1%, 5% and 10% concentrations with the values of LT50 Ae. aegypti = 9.78, 5.61, 0.24 h for larvae and LT50= 64.08, 21.23 h for pupae;Cx. quinquefasciatus had LT50= 28.46, 20.25, 1.01 h for larvae and LT50= 67.52, 27.96,4.11 h for pupae, respectively. Oviposition deterrence of the oil was evaluated on gravid females. In the study, 10% Z. limonella showed 100% repellency for Ae. aegypti and99.53% for Cx. quinquefasciatus. Likewise, oviposition activity indexes of these oil concentrations were all negative values ranging from–0.89 to-1.00 for Ae. aegypti and–0.64 to–0.99 for Cx. quinquefasciatus. The oviposition activity indexes values revealed that Z. limonella oil has deterrent effect, and it caused a remarkable negative response resulting in very few eggs.Conclusions: This result indicates that Z. limonella oil can be used as an effective adulticide, larvicide and oviposition deterrent against Ae. aegypti and Cx. quinquefasciatus.
文摘Objective: To investigate the larvicidal activity of Syzygium guineense(Myrtaceae)(S. guineense), Monodora myristica and Zanthoxylum heitzii(Rutaceae)(Z. heitzii) extracts against Aedes albopictus(Ae. albopictus).Methods: The larvicidal activity of the hydro-ethanolic extracts from these plant species was assessed at three different concentrations(50, 100 and 200 mg/L) on first-instar of Ae. albopictus larvae in comparison with untreated controls. Mortality rate was recorded daily for a period of 12 days. The values of LC_(50) and lethal time killing 50% of the tested individuals(LT_(50)) were calculated using the log-probit analysis.Results: The root extract of S. guineense exhibited the best activity with 100% mortality after 8 days of treatment at 200 mg/L, followed by the fruit extract of Z. heitzii with83.33% mortality at the same concentration. Nonetheless, larvae were most susceptible to the fruit extract of Z. heitzii both in terms of LC_(50)(39.89 mg/L) and LT_(50)(145.68 h). A statistically significant difference between the control and the group treated at 200 mg/L was noticed in all the extracts.Conclusions: The present study shows that the hydro-ethanolic extracts of S. guineense,Monodora myristica and Z. heitzii tested have significant larvicidal activity. These preliminary results are of great interest and some of these plant species can be proposed for the formulation of new bioinsecticides to control Ae. albopictus populations.
基金the financial support provided by The University of Burdwan,India
文摘Objective:To establish the larvicidal activities,if any of solvent extracts of Rauvolfia serpentina (R.serpentina) L.seeds against Culex quinquefasciatus(Cx.quinquefasciatus) Say.1823 as target species.Methods:Seeds of R.serpentina were extracted with five solvents graded according to the polarity[viz.petroleum ether.benzene,ethyl acetate,acetone and absolute alcohol] continuing one after another with the same seeds.Results:Mortality rate with petroleum ether extract was significantly higher than other extracts.The mortality rates of late 3rd instar larvae wore 50.33±5.51.10.00±1.00.0.00±0.00.21.33±1.53 and 0.00±0.00 in 100 ppm concentration of petroleum ether,benzene,ethyl acetate,acetone and absolute alcohol respectively,after 24 h of exposure period.Conclusions:Results of this study show that petroleum ether extract of R. serpentina seed may be considered as a potent source of mosquito larvicidal agent.
基金The University of Burdwan for the facilities provided and acknowledges the financial support provided by The University of Burdwan,India
文摘Objective:To investigate the larvicidal activities of crude and chlor of orm:methanol(1:1 v/ v) extracts of some common spices(Cuminum cyminum,Allium sativum,Zingiber offinale, Curcuma longa) and vegetable waste(Solanum tuberosum germinated tuber) against Anopheles stephensi and Culex quinquefasciatus mosquito larvae.Methods:Larval mortality of above mosquito species were observed after 24,48 and 72 h of exposure to five concentrations of aqueous extract(0.1%,0.2%,0.3%,0.4%and 0.5%) and four concentrations(25,50,75 ppm) of chlor of orm:methanol(1:1 v/v) extract.The lethal concentration of individual spices or vegetable waste was determined by log-probit analysis(at 95%confidence level) and effect of crude and chlor of orm:methanol(1:1 v/v) extracts were recorded on non target organisms.Results: Relative mortality rate of both larval mosquito species were recorded in the following sequences: Cuminum cyminum】 Allium sativum】Zingiber offinale,Curcuma longa 】 Solanum tuberosum germinated tuber for crude extract,and efficacy of chlor of orm:methanol(1:1 v/v) extract were as follows:Curcuma longa 】 Zingiber offinale 】 Solanum tuberosum germinated tuber 】 Cuminum cyminum】 Allium sativum.Conclusions:Crude and chlor of orm:methanol(1:1 v/v) extract of Cuminum cyminum,Allium sativum,Zingiber offinale,Curcuma longa and Solanum tuberosum germinated tuber can be recommended effectively in mosquito control programmes at very low concentrations.No mortality and other abnormalities were noticed on non target organisms and further studies are needed to investigate the chemical structure of active principal which are responsible for larvicidal activity.
