Chemical Composition and Use of Momordica charantia L. and Hyptis spicigera Lam. Extracts as Mosquito Larvicides and Insect Growth Regulators against Malarial Vector, Anopheles gambiae Giles

Background: Mosquitoes are responsible of numerous vector-borne diseases and among these diseases is malaria which takes away lives of thousands of people, especially children of under five, particularly in Africa. To reduce the mortality and economic burdens of this deadly disease, synthetic insecticide has been of use to control its main vector, Anopheles gambiae. Due to adverse effects caused by these conventional products on non-target organisms and the environment, plants have been of first choice as they proved their effectiveness against mosquitoes and are said to be eco-friendly and relatively safer. Therefore, the aim of this study was to screen the phytochemicals and determine the larvicidal and adult emergence exhibitory activities of Momordica charantia and Hyptis spicigera leaves extracts against Anopheles gambiae larvae. Methods: The WHO standard protocol for larvicidal activity and IGRs was followed up and concentrations from 500 - 2000 ppm for larvicidal and 500 - 1500 ppm for IGRs were set up. Results: There was the presence of alkaloids, flavonoids, tannins, phenols, steroids, terpenoids and oils in Momordica charantia against alkaloids, taponins, tannins, phenols, steroids, terpenoids and oils in Hyptis spicigera. Methanol crude extract registered the lowest LC50 value of 270.6 ppm followed by ethyl acetate and hexane fractions recorded the LC50 of 742.1 and 756 ppm, respectively for larvicidal activity of Momordica charantia against LC50 of 760 and 867.5 ppm for hexane fraction and methanol crude extract, respectively for Hyptis spicigera. Methanol crude extract and hexane fraction of both plants as well as the ethyl acetate fraction of M. charantia registered greater emergence inhibition with IE50 values of 590.2, 842.3 and 982 ppm for methanol crude extract, hexane and ethyl acetate fractions of M. charantia, respectively against 901.7 and 873.2 for methanol crude extract and hexane fraction of H. spicigera, respectively. Conclusion: The toxicity and adult emergence inhibition may be associated with constituents in both plants that interfere with the normal neuronal, respiratory and endocrine systems functions.

Chemical Composition, Larvicidal and Adult Emergence Inhibition Activities of Balanites aegyptiaca Del. Seed and Aristolochia albida Duch. Root Extracts against Malaria Vector, Anopheles gambiae Giles

Background: Anopheles gambiae is enemy number one of mankind in Africa and particularly in Cameroon due to its ability of transmitting malaria which is the deadliest disease in this part of the world. Synthetic insecticides have been used to control malaria vectors but they have negative effects on non-target organisms and are environmentally unfriendly. Control of mosquitoes at larval stages using phytochemicals is currently the leading tool to reduce the mosquito population and so the reduction of malaria transmission rates. Therefore, the present study was to evaluate the phytochemical contents, larvicidal and adult emergence inhibition activities of Balanites aegyptiaca seed and Aristolochia albida root solvents extracts against Anopheles gambiae larvae. Methods: The World Health Organization standard protocols were followed for the different bioassays. Concentrations ranging from 500 - 2000 ppm for larvicidal and 500 - 1500 ppm for IGRs were used. Results: Both plants showed the presence of alkaloids, flavonoids, saponins, tannins, phenols, terpenoids and oils except the absence of phenols in Aristolochia albida. The larvicidal activity of Aristolochia albida extracts showed that hexane and methanol fractions were the most active killing relatively all exposed larvae with the LC50 values of 420.1 and 453 ppm, respectively. The same observation was made in hexane fraction from Balanites aegyptiaca (LC50 = 588 ppm). The insect growth inhibitory activity of Aristolochia albida extracts proved that hexane and methanol fractions relatively caused a 100% inhibition in the mosquito development, recording the EI50 values of 482.4 and 555.6 ppm, respectively. The same trend was observed with Balanites aegyptiaca hexane fraction registering better EI50 of 623.9 ppm. Conclusions: Our findings demonstrate that Balanites aegyptiaca seed and Aristolochia albida seed extracts are rich in phytochemicals capable of killing mosquito larvae and disrupting mosquito larval development. This could contribute to the control of mosquito populations and improved management of malaria.

Larvicidal and repellent potential of Moringa oleifera against malarial vector,Anopheles stephensi Liston(Insecta:Diptera:Culicidae)

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.

Ovicidal and repellent activities of botanical extracts against Culex quinquefasciatus,Aedes aegypti and Anopheles stephensi(Diptera:Culicidae)

Objective:To determine the ovicidal and repellent activities of methanol leaf extract of Ervatamia coronaria(E.coronaria) and Caeslpinia pulckerrima(C.pulcherrima) against Culex quinquefasciatus(Cx.quinquefasciatus),Aedes aegypti(Ae.aegypti) and Anopheles stephensi(An. stephensi).Methods:The ovicidal activity was determined against three mosquito species at various concentrations ranging from 50-450 ppm under the laboratory conditions.The hatch rates were assessed 48 h after treatment.The repellent efficacy was determined against three mosquito species at three concentrations viz.,1.0,2.5 and 5.0 mg/cm under the laboratory conditions. Results:The crude extract of E.coronaria exerted zero hatchability(100%mortality) at 250.200 and 150 ppm for Cx.quinqitefasciatus,Ae.aegypti and An.stephensi,respectively.The crude extract of C.pulchenima exerted zero hatchability(100%mortality) at 375.300 and 225 ppm for Cx.quinquefasciatus,Ae.aegypti and An.Stephensi,respectively.The methanol extract of E. coronaria found to be more repellenct than C.pukherrima extract.A higher concentration of 5.0 mg/cm^2 provided 100%protection up to 150.180 and 210 min against Cx.quinquefasciatus,Ae. aegypti and An.stephensi,respectively.The results clearly showed that repellent activity was dose dependent.Conclusions:From the results it can be concluded the crude extracts of E.coronaria and C.pukherrima are an excellent potential for controlling Cx.quinquefasciatus,Ae.aegypti and An.stephensi mosquitoes.

Responsiveness of Anopheles maculipennis to different imagicides during resurgent malaria

Objective:To determine the susceptibility of main malaria vector in Astra County,borderline of Iran and Republic of Azerbaijan for better control.Methods:Susceptibility of Anopheles mactdipennis to diagnostic doses of DDT 4% ,dieldrin 0.4% ,malathion 5% ,lambdacyhalothrin 0.1% ,and delamethrin 0.025% ,was tested according to method recommended by WHO.All the impregnated papers were provided by WHO.Results:It was shown that this species exhibited resistance to DDT,dieldrin,whereas susceptible to malathrion,lambdacyhalothrin and deltamethrin.Conclusions:Findings of susceptibility tests of this species provided a clue for control of malaria vector in the region.

Mosquito adulticidal and repellent activities of botanical extracts against malarial vector,Anopheles stephensi Liston(Diptera:Culicidae)

ObjectiveTo determine the adulticidal and repellent activities of different solvent leaf extracts of Eclipta alba (E. alba) and Andrographis paniculata (A. paniculata) against malarial vector, Anopheles stephensi (An. stephensi).MethodsAdulticidal efficacy of the crude leaf extracts of E. alba and A. paniculata with five different solvents like benzene, hexane, ethyl acetate, methanol and chloroform was tested against the five to six day old adult female mosquitoes of An. stephensi. The adult mortality was observed after 24 h under the laboratory conditions. The repellent efficacy was determined against An. stephensi mosquito species at three concentrations viz., 1.0, 2.5 and 5.0 mg/cm2 under laboratory conditions.ResultsAmong the tested solvents the maximum efficacy was observed in the methanol extract. The LC50 and LC90 values of E. alba and A. paniculata against adults of An. stephensi were 150.36, 130.19 ppm and 285.22, 244.16 ppm, respectively. No mortality was observed in controls. The chi-square values were significant at P<0.05 level. Methanol extract of E. alba and A. paniculata was produce maximum repellency against An. stephensi.ConclusionsFrom the results it can be concluded the crude extract of E. alba and A. paniculata was an excellent potential for controlling An. stephensi mosquitoes.

Mosquito larvicidal and pupicidal activity of Euphorbia hirta Linn.(Family:Euphorbiaceae) and Bacillus sphaericus against Anopheles stephensi Liston.(Diptera:Culicidae)

Objective:To explore the larvicidal and pupicidal activity of Euphorbia hirta（E.hirta） leaf extract and Bacillus sphaericus（B.sphaericus） against the malarial vector.Anopheles siephensi（An. stephensi）.Methods:The larvicidal and pupicidal activity was assayed against An.stephensi at various concentrations ranging from（75-375 ppm） under the laboratory as well as field conditions. The LC50 and LC90 value of the E.hirta leaf extract was determined by probit analysis.Results: The plant extract showed larvicidal effects after 24 h of exposure;however,the highest larval mortality was found in the methanol extract of E.hirta against the first to fourth instars larvae and pupae of values LC50=137.40,172.65,217.81,269.37 and 332.39 ppm;B.sphaericus against the first to fourth instars larvae and pupae of values LC50= 44.29,55.83,68.51,82.19 and 95.55 ppm, respectively.Moreover,combined treatment of values of LC50= 79.13,80.42,86.01,93.00 and 98.12 ppm,respectively.No mortality was observed in the control.Conclusions:These results suggest methanol leaf extracts of E.hirta and B.sphaericus have potential to be used as an ideal ecofriendly approach for the control of the malarial vector.An.stephensi as target species of vector control programs.This study provides the first report on the combined mosquito larvicidal and pupicidal activity of this plant crude extract and bacterial toxin against An.stephensi mosquitoes.

Toxicity of several botanical essential oils and their combinations against females of Aedes albopictus(Skuse) and Anopheles minimus(Theobald): Oviposition deterrent, ovicidal and adulticidal efficacies

Objective: To investigate the efficacies of 12 essential oil(EO) formulations from three Zingiberaceae plants(Alpinia galanga, Curcuma zedoaria, and Zingiber cassumunar) individually and in combination with an augmenting Eucalyptus globulus(E. globulus) EO against females of Aedes albopictus(Ae. albopictus) and Anopheles minimus(An. minimus). Methods: These formulations were evaluated for their ovicidal, oviposition deterrent and adulticidal activities against Ae. albopictus and An. minimus by a topical method, a double-choice method and a WHO susceptibility test, respectively. Results: It was found that all formulations of Zingiberaceae plants EOs augmented with E. globulus EO were more effective in oviposition deterrent, ovicidal, and adulticidal activities against the two mosquito species than all of the formulations used without E. globulus EO. Their oviposition deterrent, ovicidal and adulticidal activities were equivalent to those of 10% w/v cypermethrin. In contrast, 70% v/v ethyl alcohol as a control alone was not effective at all. The highest synergistic effect in effective repellency against Ae. albopictus was achieved by 5% Alpinia galanga EO + 5% E. globulus EO and against An. minimus was 5% Zingiber cassumunar EO + 5% E. globulus EO. Moreover, the highest synergistic effects in ovicidal activities against Ae. albopictus and An. minimus were achieved by 10% Zingiber cassumunar EO + 10% E. globulus EO and 5% Curcuma zedoaria EO + 5% E. globulus EO, respectively. For the adulticidal activities, the highest synergistic effect against two mosquitoes was achieved by 5% Curcuma zedoaria EO + 5% E. globulus EO. Conclusions: These results suggest that Zingiberaceae plant EOs augmented with E. globulus EO have a high potential to be developed into oviposition deterrent, ovicidal, and adulticidal agents for controlling populations of Ae. albopictus and An. minimus.

Mosquito larvicidal properties of Ficus henghalensis L.(Family:Moraceae) against Culex tritaeniorhynchus Giles and Anopheles subpictus Grassi(Diptera:Culicidae)

Objective:To determine the larvicidal efficacy of different solvent leaf extract of Ficus benghalensis（F.benghalensis） against Culex tritaeniorhynchus（Cx.tritaeniorhynchus） and Anopheles subpictus（An.subpictus）.Methods:Twenty five early third instar larvae of Cx. tritaeniorhynchus and An.subpictus were exposed to various concentrations and were assayed in the laboratory by using the protocol of WHO 2005.The larval mortality was observed after 24 h of treatment.Results:Among three solvent extracts tested the maximum efficacy was observed in the methanol extract.The LC50 and LC90 values of F.benghalensis against early third instar of Cx. tritaeniorhynchus and An.subpictus were 100.88.159.76 ppm and 56.66.85.84 ppm.respectively. No mortality was observed in controls.The chi-square values were significant at P【0.05 level. Conclusions:From the results it can be concluded the crude extract of F.benghalensis was an excellent potential for controlling Cx.tritaeniorhynchus and Art.subpictus mosquito larvae.

Relationship of Remote Sensing Normalized Differential Vegetation Index to Anopheles Density and Malaria Incidence Rate

Objective To study the relationship of remote sensing normalized differential vegetation index （NDVI） to Anopheles density and malaria incidence rate. Methods Data of monthly average climate, environment, Anopheles density and malaria incidence rate, and remote sensing NDVI were collected from 27 townships of 10 counties in southeastern Yunnan Province from 1984 to 1993. The relationship of remote sensing ecological proxy index, NDVI, to Anopheles density and malaria incidence rate was studied by principal component analysis, factor analysis and grey correlation analysis. Results The correlation matrix showed that NDVI highly correlated with Anopheles density in 4 townships of Mengla, Jinghong, and Yuanjiang counties, but in other 23 townships the relationship was not clear. Principal component and factor analyses showed that remote sensing NDVI was the representative index of the first principal component and the first common factor of Anopheles density evaluation. Grey correlation analysis showed that in rainy season NDVI had a high grey correlation with Anopheles density and malaria incidence rate. The grey correlation analysis showed that in rainy season the grey degree of NDVI correlated with Anopheles. Minimus density was 0.730, and 0.713 with Anopheles sinensis density, and 0.800 with malarial incidence rate. Conclusion Remote sensing NDVI can serve as a sensitive evaluation index of Anopheles density and malaria incidence rate.

福建省嗜人按蚊Anopheles anthropophagus地理布分及生态习性调查

嗜人接蚊是我国南方疟疾和马来丝虫病的主要传播媒介。1980我们在崇安五夫和建阳周墩开展疟疾和马来丝虫流行病学调查,发现它的子孢子和感染蚴自然感染率分别为0.4%和5.2%。为采取相应防制措施,降低该蚊种群密度,以期控制疟疾和马来丝虫病在我省的流行,我们从1980年开始,开展嗜人按蚊在省内的地理分布及其生态习性调查。现将结果报告如下:

Comparative efficacy of neem and dimethyl phthalate (DMP) against malaria vector,Anopheles stephensi (diptera:culicidae)

Malaria is one of the most important parasitic diseases in the world which is transmitted by the Anopheles mosquitoes. There are several methods for malaria control.One of them is application of repellents on skin in malarious area as an intergrated vectro management measures.This study evaluated two repellents of DMP as a synthtic and locally product of neem oil as a botanical repellent against Anopheles stephensi.The modified method of K & D was used for the tests.Probing/biting rates on the shaved belly of white rabbits were counted. ED50 and ED95 values were calculated by probit statistic software.Calculation of effective dose(ED50, ED90 ) on human volunteer and white rabbit was performed using regression line.Protection and failure time of DMP and neem oil was also determined.ED50 value of DMP and neem oil was determined as 0.0076 and 0. 159 mg/cm respectively on white rabit.The figures of ED90 value of DMP and neem oil was determined as 0. 046 and 1.388 mg/cm^2.DMP and neem oil showed repellency effects against An.stephensi on human volunteers with ED50 value of 0.0037 and 0.127 mg/cm^2 respectively.ED90 value of DMP was determined as 0. 032 mg/cm^2.neem oil exhibited a ED90 value of 1.066 mg/cm^2 on human volunteer.The protection time of 6-7 hours for DMP and 31 minute for neem oil was determined.The failure times for DMP and Neem was 9 hours and 65 minutes rspectively on human bait.Our results exhibited that plant-based repellent is generally less effective than synthetic repellents.However,use of locally made botanical materials would be of great advantages for personal protection against mosquito biting.

Mosquito larvicidal properties of Orthosiphon thymiflorus(Roth)Sleesen.(Family:Labiatae)against mosquito vectors,Anopheles stephensi,Culex quinquefasciatus and Aedes aegypti(Diptera:Culicidae)

Objective:To determine the mosquito larvicidal activities of hexane,chloroform,ethyl acetate, acetone and methanol leaf extract of Orthosiphon thymiflorus（O.thymiflorus） against Anopheles stephensi（An.stephensi）,Culex quinquefasciatus（Cx.quinquefasciatus） and Aedes aegypti （Ae.aegypti）.Methods:The larvicidal activity was assayed against three mosquito species at various concentrations ranging from（50-450 ppm） under the laboratory conditions.The LC50 and LC90value of the O.thymiflorus leaf extract was determined by Probit analysis.Results:The LC50 values of hexane,chloroform,ethyl acetate,acetone and methanol extract of O.thymiflorus third instar larvae of An.stephensi were LC50= 201.39,178.76,158.06,139.22 and 118.74 ppm; Cx.quinquefasciatus were LC50=228.13,209.72.183.35,163.55 and 149.96 ppm and Ae.aegypti were LC50=215.65,197.91,175.05,154.80 and 137.26 ppm,respectively.Maximum larvicidal activity was observed in the methanolic extract followed by acetone,ethyl acetate chloroform and hexane extract.The larval mortality was observed after 24 h exposure.No mortality was observed in control.Conclusions:The present results suggest that the effective plant crude extracts have potential to be used as an ideal eco-friendly approach for the control of mosquito vectors.This study provides the first report on the larvicidal activity of this plant crude solvent extract of against An.stephensi,Cx.quinquefasciatus and Ae.aegypti mosquitoes.

Larvicidal,ovicidal and pupicidal activities of Gliricidia sepium(Jacq.)(Leguminosae) against the malarial vector,Anopheles stephensi Liston(Culicidae:Diptera)

Objective:To investigate the potentiality of mosquitocidal activity of Gliricidia sepium（C.sepium） （Jacq.）（Leguminosae）.Methods:Twenty five early third instar larvae of Anopheles stephensi （An.stephensi） were exposed to various concentrations（50-250 ppm） and the 24 h LC50 values of the G.sepium extract was determined by probit analysis.The ovicidal activity was determined against An.stephensi to various concentrations ranging from 25-100 ppm under laboratory conditions.The eggs hatchabilily was assessed 48 h post treatment.The pupicidal activity was determined against An.stephensi to various concentrations ranging from 25-100 ppm.Mortality of each pupa was recorded after 24 h of exposure to the extract.Results:Results pertaining to the experiment clearly revealed that ethanol extract showed significant larvicidal,ovicidal and pupicidal activity against the An.stephensi.Larvicidal activity of ethanol extracts of G.sepium showed maximum mortality in 250 ppm concentration（96.0±2.4）%.Furthermore,the LC50 was found to be 121.79 and the LC50 value was recorded to be 231.98 ppm.Ovicidal activity of ethanol extract was assessed by assessing the egg hatchabilily.Highest concentration of both solvent extracts exhibited 100%ovicidal activity.Similarly,pupae exposed to different concentratioiLs of ethanol extract were found dead with 58.10%adult emergence when it was treated with 25 ppm concentration.Similarly,18.36（n=30;61.20%）;21.28（70.93） and 27.33（91.10） pupal mortality was recorded from the experimental pupae treated with 50,75 and 100 ppm concentration of extracts. Three fractions have been tested for their larvicidal activity of which the Fraction 3 showed the LC50 and LC90 values of 23.23 and 40.39 ppm.With regard to the ovicidal effect fraction 3 showed highest ovicidal activities than the other two fractions.Furthermore,there were no hatchabilily was recorded above 50 ppm（100%egg mortality） in the experimental group.Statistically significant pupicidal activity was recorded from 75 ppm concentration.Conclusions:From the results it can be concluded the crude extract of G.sepium is an excellent potential for controlling An.stephensi mosquito.It is apparent that,iraction 3 possess a novel and active principle which could be responsible for those biological activities.

Molecular characterization,biological forms and sporozoite rate of Anopheles stephensi in southern Iran

Objective:To identify the biological forms,sporozoite rate and molecular characterization of the Anopheles stephensi(An.stephensi)in Hormozgan and Sistan-Baluchistan provinces,the most important malarious areas in Iran.Methods:Wild live An.stephensi samples were collected from different malarious areas in southern Iran.The biological forms were identified based on number of egg-ridges.Molecular characterization of biological forms was verified by analysis of the mitochondrial cytochrome oxidase subunit I and II(mtDNA-COI/COII).The Plasmodium infection was examined in the wild female specimens by species-specific nested-PCR method.Results:Results showed that all three biological forms including mysorensis,intermediate and type are present in the study areas.Molecular investigations revealed no genetic variation between mtDNA COI/COII sequences of the biological forms and no Plasmodium parasites was detected in the collected mosquito samples.Conclusions:Presence of three biological forms with identical sequences showed that the known biological forms belong to a single taxon and the various vectorial capacities reported for these forms are more likely corresponded to other epidemiological factors than to the morphotype of the populations.Lack of malaria parasite infection in An,stephensi,the most important vector of malaria,may be partly due to the success and achievement of ongoing active malaria control program in the region.

Efficacy of larvicidal and pupicidal activity of Catharanthus roseus aqueous and solvent extracts against Anopheles stephensi Liston and Culex quinquefasciatus Say (Diptera: Culicidae)

Objective: To investigate the larvicidal and pupicidal activities of aqueous, ethyl acetate and methanol extracts of Catharanthus roseus ( C. roseus ) against malaria and filariasis vectors. Methods: The larvicidal and pupicidal activities of C. roseus leaf extracts were tested against the fourth instar larvae and pupae of Anopheles stephensi ( An. stephensi ) and Culex quinquefasciatus ( Cx. quinquefasciatus ). The mortality was observed after 24 and 48 h post the treatment. The data were subjected to probit analysis to determine the lethal concentrations (LC 50 and LC 90 ) at which 50% and 90% of the treated larvae or pupae of the tested species were killed. Results: The larval and pupal mortality were observed after 24 and 48 h of exposure of aqueous, ethyl acetate and methanol extracts of C. roseus ; no mortality was observed in the control group. The LC 50 values against the fourth-instar larvae of An. stephensi were 68.62 and 72.04 mg/mL for the aqueous extract, 82.47 mg/mL for the ethyl acetate extract, and 78.80 and 86.64 mg/mL for the methanol extract, while the aqueous, ethyl acetate and methanol extracts had LC 50 values of 85.21, 76.84 and 94.20 mg/mL against the fourth-instar larvae of Cx. quinquefasciatus . The aqueous, ethyl acetate and methanol extracts had LC 50 values of 118.08, 182.47 and 143.80 mg/mL against the pupae of An. stephensi and 146.20, 226.84 and 156.62 mg/mL against the pupae of Cx. quinquefasciatus , respectively. Conclusions: The aqueous and methanol extracts of C. roseus leaves had an excellent potential to control the malarial vector An. stephensi and filariasis vector Cx. quinquefasciatus .

Larvicidal activities of chinaberry,neem and Bacillus thuringiensis israelensis(Bti) to an insecticide resistant population of Anopheles arabiensis from Tolay,Southwest Ethiopia

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.

Phytochemistry and larvicidal activity of Eucalyptus camaldulensis against malaria vector,Anopheles stephensi

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 LC50 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.

In vitro larvicidal potential against Anopheles stephensi and antioxidative enzyme activities of Ginkgo biloba,Stevia rebaudiana and Parthenium hysterophorous

Objective:To investigate in vitro larvicidal and antioxidant enzymes potential of the medicinal plants Ginkgo biloba（G.biloba）,Stevia rebaudiana（S.rebaudiana） and Parthenium hysterophorous（P.hysterophorous） against Anopheles stephensi（An.stephensi） 4th instars larvae. Methods:For evaluation of larvicidal potential,the ethanolic,methanolic and dichloromethane leaves extracts of three different plants were used in dose-dependent experiments in two media, while the antioxidant enzymes activities were investigated using four different methods viz., superoxide dismutase,peroxidase,ascorbate and catalase.Results:An.stephensi has developed resistance to various synthetic insecticides,making its control increasingly difficult.The comparative performance of ethanolic extracts（65%-90%） was found better than the methanolic extract（70%-87%） and dichloromethane extract（60%-70%）.Among the three plants extracts tested in two media,S.rebaudiana exhibited higher larvicidal activity with LC50（24 h） in methanolic extract than P.hysterophorous and G.biloba.G.biloba and P.hysterophorous exhibited the strongest antioxidative enzymes activity and S.rebaudiana were less active and no significant difference was observed.Conclusions:These three plants exhibit larvicidal potential and can be further used for vector control alternative to synthetic insecticide due to eco-friendly and diseases control,furthermore these plant species have potent antioxidative enzyme activities, therefore,making them strong natural candidate particularly for diseases which are caused due to free radicals.

Susceptibility of Anopheles maculipennis to different classes of insecticides in West Azarbaijan Province, Northwestern Iran

Objective: To determine the susceptibility status of Anopheles maculipennis(An. maculipennis) against the major insecticides used in the health sectors in West Azarbaijan Province, Northwestern Iran.Methods: Unfed 3-5 days old adult females of An. maculipennis were collected across the West Azarbaijan Province and were subjected to evaluation of their susceptibility following World Health Organization recommended protocol against six insecticides(permethrin, deltamethrin, propoxur, bendiocarb, malathion and dieldrin) belonging to four different classes. Results: In this study, 916 specimens of An. maculipennis were examined against the insecticides which indicated that An. maculipennis was tolerant to permethrin, deltamethrin and dielderin, but displayed resistance against propoxur, bendiocarb and malathion. Conclusions: The pattern of resistance in An. maculipennis could be attributed to the agricultural landscapes, agricultural pesticides used and the exposure of the mosquitoes to insecticides. Logical cooperation is needed between the agriculture and health sectors to ensure the judicious use of pesticides in each sector and the management of probable resistance.