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

To 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）Mathods:Adultieidal efficacy of the crude leaf extracts of E.alba and.1.paniculata with five different solvents like benzene,hexane.ethyl acetate. methanol and chloroform was tested against the five to six dav 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.Results:Among 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 obsened in controls.The chi-square values were significant at P【0.05 lev el.Methanol extract of E.alba and A.paniculata was produce maximum repellency against An.stephensi.Conclusions:From the results it can be concluded the crude extract of E. nihil and A.paniculata was an excellent potential for controlling An.stephensi mosquitoes.

Adult emergence inhibition and adulticidal activities of medicinal plant extracts against Anopheles stephensi Liston

Objective:To determine the adult emergence inhibition（EI） and adulticidal activities of hexane,chloroform,ethyl acetate,and acetone leaves extracts of Anisomeles malabarica（A. malabarica）,Euphorbia hirta（E,hirta）,Ocimum basilicum（0.basilicum）,Ricinus communis（R. communis）,Solanum trilobatum（S.trilobatum）,Tridax procumbens（T.procumbens） and seeds of Gloriosa superba（G.superba） against Anopheles stephensi（An,stephensi）.Methods:The EI and adulticidal trials were carried out according to World Health Organization（WHO） procedures with slight modifications.The extracts were diluted in dimethyl sulphoxide in order to prepare a serial dilution of test dosages（15.625,31.25,62.5,125,250,500 and 1 000μg/mL）.Five duplicate trials were carried out for every sample concentration,and for each trial a negative control was included and the mortality was determined after 24 h of exposure.Results:The highest EI activity was found in ethyl acetate extracts of A malabarica,chloroform extracts of O.basilicum, S.trilobatum,acetone of extract of R.communis,T.procumbens,and seed extract of G.superba with EI50 values 143.12,119.82.157.87,139.39,111.19,and 134.85μg/mL,and the effective adulticidal activity was observed in chloroform,acetone extracts of G.superba,T.procumbens,R. communis,S.trilobatum and ethyl acetate extract of 0.basilicum with LD50 values 120.17,108.77, 127.22,163.11,118.27,and 93.02μg/mL,respectively.Chi-square value was significant at P【0.05 level.Conclusions:These results should encourage further efforts to investigate the compounds that might possess good EI and adulticidal properties when isolated in pure form.

Repellent,larvicidal and adulticidal activities of essential oil from Dai medicinal plant Zingiber cassumunar against Aedes albopictus

Zingiber cassumunar is an important plant used in traditional medicine and as a natural mosquito re-pellent.However,the compounds responsible for the repellent activity of the plant are still unknown.The aim of the study is to identify the components of Z.cassumunar essential oil that show repellent activity against Aedes albopictus.We also evaluated the larvicidal and adulticidal activities of Z.cassumunar essential oil against Ae.albopictus.In-cage mosquito repellent experiments showed that Z.cassumunar essential oil possessed moderate repellent activity with a minimum effective dose(MED)of 0.16±0.01 mg/cm^(20,compared to reference standard N,N-diethyl-3-methylbenzamide(DEET,0.03±0.01 mg/cm^(20).Bioassay-guided fractionation identified the major active compound of Z.cassumunar essential oil as(-)-terpinen-4-ol(1)(MED:0.19±0 mg/cm^(20).We also found that Z.cassumunar essential oil showed moderate larvicidal activity against first instar larvae of Ae.albopictus with a LC50(50%lethal concentration)of 44.9 mg/L after 24 h.Fumigation bioassays showed that Z.cassumunar essential oil exhibits moderate adulticidal activity against Ae.albopictus with a LC50 of 5.44%,while(-)-terpinen-4-ol showed significant adulticidal activity with a LC50 of 2.10%after 24 h.This study verifies that the Z.cassumunar essential oil has mosquito repellent activity,and that(-)-terpinen-4-ol is mainly responsible for this activity.Furthermore,this study provides scientific support for the folk usage of Z.cassumunar essential oil as mosquito repellent and indicates that Z.cassumunar essential oil and(-)-terpinen-4-ol can be used as plant-derived repellents and insecticides for mosquito control.

Larvicidal and adulticidal potential of medicinal plant extracts from south India against vectors

Objective:To determine the larvicidal and adulticidal activities of hexane,ethyl acetate and methanol extracts of Momordica charantia（M.charantia）,Moringa oleifera（M.oleifera）,Ocimum gratissimum（O.gratissimum）,Ocimum tenuiflorum（0.tenuiflorum）,Punica granalum（P. granatum） and Tribulus terrestris（T.terrestris） against Culex gelidus（Cx.gelidus） and Culex quinquefasciatus（Cx.quinquefasciatus）.Methods:Bioassay test was carried out by WHO method for determination of larvicidal and adulticidal activity against mosquitoes.Results:All plant extracts showed moderate larvicidal and adulticidal activities,however the effective larval mortality was found in the leaf ethyl acetate and methanol extract of O.gratissimum and bark methanol extract of M.oleifera against Cx.gelidus with LC50 values of 39.31.66.28,and 21.83μg/mL respectively,and methanol extract of 0.gratissimum,0.tenuiflorum and P.granatum against Cx.quinquefasciatus with LC50 values of 38.47.24.90 and 67.20μg/mL,respectively.The adult exposed for 1 h and mortality was recorded at 24 h recovery period.Above 90%- mortality was found in the ethyl acetate and methanol extract of all experimental plants at the concentrations of 500μg/mL.Conclusions:The present results suggest that the medicinal plant extracts provided an excellent potential for controlling Cx.gelidus and Cx.quinquefasciatus.

Anopheles gambiae larvicidal and adulticidal potential of Phyllanthus amarus(Schumach and Thonn,1827)obtained from different localities of Nigeria

Objective:To screen phytochemicals in ethanolic leaf extracts of Phyllanthus amarus collected from three different geographical zones in Nigeria and evaluate their effects on larva and adult of Anopheles gambiae.Methods:The sample extracts of Phyllanthus amarus prepared with ethanol solvent were tested against Anopheles gambiae at two important developmental stages of its life cycle using slightly modified WHO protocols.Results:Alkaloids,saponins,tannins,flavonoids,glycosides,phenols,and terpenes were detected in each extract.Among these samples,the extract from northwest exhibited the highest larvicidal activity(LC50=263.02 ppm),followed by southeast and southwest extracts(LC50=288.40 and 295.12 ppm,respectively after 48 h),while the extract from southwest exhibited the highest adulticidal activity(LC50=275.42 ppm),followed by northwest and southeast extract(LC50=301.99 and 316.22 ppm,respectively after 24 h).A 50%larva mortality was almost attained at 600 ppm after 48 h duration of exposure to the northwest extract.Conclusions:The tested samples possess strong larvicidal and adulticidal property against Anopheles gambiae which depends on their chemical composition and localities of collection.Further studies are needed to explore the insecticidal activity against a wider range of mosquito species,and to identify active ingredient(s)of the extract responsible for such activity.

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.

Adulticidal, larvicidal, pupicidal and oviposition deterrent activities of essential oil from Zanthoxylum limonella Alston(Rutaceae) against Aedes aegypti(L.) and Culex quinquefasciatus(Say)

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.

Mosquito adulticidal properties of Delonix elata(Family:Fabaceae)against dengue vector,Aedes aegypti(Diptera:Culicidae)

Objective:To determine the adulticidal activity of hexane,benzene,chloroform,ethyl acetate and methanol leaf and seed extracts of Delonix elata(D.elata)against Aedes aegypti(Ae.aegypti).Methods:The bioassay was conducted in an experimental kit consisting of two cylindrical plastic tubes both measuring 125 mm×44 mm following the WHO method;mortality of the mosquitoes was recorded after 24 h.Results:The adulticidal activity of plant leaf and seed extracts showed moderate toxic effect on the adult mosquitoes after 24 h of exposure period.However,the highest adulticidal activity was observed in the leaf methanol extract of D.elata against Ae.aegypti with the LC_(50) and LC_(90) values 162.87 and 309.32 mg/L,respectively.Conclusions:From this result,it can be concluded the crude extract of D.elata was an excellent potential for controlling Ae.aegypti mosquitoes.

Melaleuca quinquinervia(Cav.) S.T. Blake(Myrtales:Myrtaceae):Natural alternative for mosquito control

Objective: To evaluate an essential oil with larvicide, adulticide and growth inhibitory activity against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus mosquitoes, of medical importance. Methods: Standardized methodology by WHO was used to determine the levels of susceptibility of mosquito larvae exposed to the essential oil. To evaluate the adulticide activity with the essential oil at different doses, bottles were impregnated according to the methodology CDC. To determine the development inhibitory activity of Melaleuca quinquinervia(M. quinquinervia) oil in three mosquito species, third instar larvae were exposed to the LC_(50) and LC_(90) dose(calculated for each population) of M. quinquinervia oil in glass containers with a capacity of 500 mL. After 24 h exposure, the dead larvae were discarded. The mortality of larvae and pupae were recorded on a daily basis. Results: The calculated LC_(50) indicates an order of effectiveness of preferential oil for Culex quinquefasciatus(LC_(50)=0.002 1%), Aedes aegypti(LC_(50)=0.004 7%) and Aedes albopictus(LC_(50)=0.004 9%). Conclusions: The adulticide activity was achieved with impregnated bottles at 40 and 50 mg/mL with the three mosquitoes species. In larvae, a growth inhibition was detected when exposed to sublethal doses. The results indicate that M. quinquinervia is a plant with promising environmentally sustainable source for vector control.

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

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 aegypli(Ae.Aegypti).Methods:The larvicidal potential of peppermint oil was evaluated against early fourth instar larvae of Ae.aegypli 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 rain 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 48h.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.oviposition deterrent and ovicidal agent.The isolation of active ingredient from the oil could help in formulating strategies for mosquito control.

New Thai herbal shampoos as pediculicides for killing head louse, Pediculus humanus capitis De Geer(Phthiraptera)

Objective: To evaluate the efficacy of Thai herbal shampoos [Cartoxylum formosum(C.formosum) + eucalyptus essential oil(EO), C. formosum + citrus EO, Solanum trilobatum+ eucalyptus EO, Solanum trilobatum + citrus EO, Moringa oleifera + eucalyptus EO and Moringa oleifera + citrus EO] for killing all stages of Pediculus humanus capitis(Phthiraptera).Methods: A filter paper contact method was applied with three concentrations(0.05, 0.10 and 0.20 mL/cm^2) of each Thai herbal shampoo as well as permethrin pediculicide(positive control) and drinking water(negative control) against eggs, nymphs and adults of Pediculus humanus capitis. Mortality rates of the eggs were recorded after 7 days of incubation while those of nymphs and adults were recorded after 5 minutes of contact. Results: All herbal shampoos at the high concentration were highly effective against nymphs and adults, but not effective against the eggs. C. formosum + eucalyptus EO and C. formosum + citrus EO shampoos at all concentrations exhibited the highest efficacy against nymphs and adults with100% mortality rate at 5 min and LC_(50) values of 0.004 and 0.005 mL/cm^2, respectively. All formulation of Solanum trilobatum and Moringa oleifera shampoos added with eucalyptus EO showed mortality rates against nymphs at 92.0%-100.0% and 76.0%-100.0% and against adults at 84.0%-100.0% and 20.0%-32.0%, respectively. Permethrin pediculicide was not effective against the eggs, but showed 68.0%-92.0% and 28.0%-60.0% mortality rates against nymphs and adults. Conclusions: These results indicate that C. formosum + eucalyptus EO shampoo can be used as an effective nymphicide and adulticide against Pediculus humanus capitis.

Bioactivity of essential oils of local plants against adult <i>Anopheles arabiensis</i>(Diptera: Culicidae) in Ethiopia

The adulticidal activities of essential oils of eleven plants namely Chenopodium ambrosioides, Eucalyptus citriodora, Eucalyptus globules, Lippia adoensis, Mentha spicata, Nigella sativa, Ocimum lamiifolium, Ocimum suave, Piper nigrum, Schinus molle and Thymus vulgaris were assessed against a laboratory colony of Anopheles arabiensis in Ethiopia. The Centers for Disease Control and Prevention (CDC) glass bottle bioassay was adopted to conduct bioefficacy tests. For each replicate, ten blood-unfed female An. arabiensis were exposed to different concentrations of essential oils coated in glass bottles, and mortality was recorded at intervals of 5 minutes for one hour to assess the mean percentage mortality and LC50 and LC90 values. The residual toxicity of six essential oils was also assessed by exposing adult An. arabiensis in nylon netting Barraud cages treated by oils. Of all the essential oils assessed for adulticidal activities, O. suave was found to be toxic at low concentration (LC50 = of 0.0014 ml% v/v;LC90 = 0.0027 ml% v/v). The next efficacious oil was that of T. vulgaris with LC50 and LC90 values of 0.0028 ml% v/v and 0.005 ml% v/v, respectively. The lowest activity was due to S. molle, E. globulus and P. nigrum. At a concentration of 0.05 ml% v/v, O. suave killed 100% of An. arabiensis within five minutes of exposure, while P. nigrum at the same duration caused similar rate of mortality at a concentration of 50 fold. Residual toxicity tests revealed O. suave to persist for 15 days, killing all mosquitoes in the first five days and 80% up to 10 days. The lowest residual activity was noted for E. citriodora which persisted only for 2 days. The essential oil O. suave acquired the highest level of toxicity at low concentration and within a short time. The efficacious nature of most plants has an implication for more screening of components of these plants with potential adulticides and develops for mosquito control.

Phomalactone as the Active Constituent against Mosquitoes from <i>Nigrospora spherica</i>

The culture filtrate of a plant pathogenic fungus that infected Zinnia elegans and Hydrangea macrophylla was investigated for mosquitocidal constituents by bioassay guided isolation. The fungus responsible for the pathogenic effects on Zinnia elegans and Hydrangea macrophylla plants had been identified as Nigrospora spherica by molecular techniques. The mosquito adulticidal constituent in the culture filtrate was identified as phomalactone by spectroscopic techniques. Laboratory bioassays showed that phomalactone had larvicidal activity against permethrin susceptible and resistant Aedes aegypti larvae and topical adulticide activities on permethrin susceptible and resistant Aedes aegypti and Anopheles quadrimaculatus mosquitoes. Phomalactone was effective as a topical adulticide against the standard Orlando reference strain of Ae. aegypti with an LD50 of 0.64 μg/org. Activity against An. quadrimaculatus was 0.20 μg/org.