Instar Larvae Of Cx Research Articles

Mosquito Larvicidal Potential of Salicylic Acid and 3,5-Di Nitro Salicylic Acid against Filarial Vector <i>Culex quinquefasciatus</i>

The present study was carried out to evaluate the larvicidal activity of two organic acids, namely Salicylic acid and 3, 5-Di Nitro Salicylic Acid against larvae of Culex quinquefasciatus . Bioassay experiments with graded concentrations (50 ppm, 100 ppm, 150 ppm, 200 ppm and 250 ppm) of these organic acids were used against third instars larvae of Cx. quinquefasciatus at 24 hour, 48 hour and 72 hour of exposures to ensure their larvicidal potentiality. The results of bioassay experiments showed highest mortality rate at 72h of exposure period for both the compounds. The toxicity of Salicylic Acid was higher than the 3, 5- Di Nitro Salicylic Acid . Regression analysis revealed that the mortality rate (Y) was positively correlated with the concentrations of the compounds (X). Respective Lethal toxicity values (LC 50 values and LC 90 values) gradually decreased with the exposure period. The effects of these organic acids were also tested on non target organisms such as Anisops sardea, larvae of Toxorhynchites sp. Chironomus sp. and Tadpole. There was no significant mortality occurred in non-target organism within 72h of exposure period. The results support that Salicylic acids and its Nitro derivatives can effectively be used in mosquito breeding places to reduce the density of mosquito immatures.

Bioactivity of <i>Acyranthes aspera</i> (Amaranthaceae) Foliage against the Japanese Encephalitis Vector <i>Culex vishnui</i> Group

Background and objective : Failure to develop proper vaccines against mosquito borne diseases, a global health problem, imposes sole reliance on the vector managerial steps for reducing the disease incidences. Easy abundance, cost effectiveness, target specificity as well as bio-degradability of botanicals draw the most attention as vector control agents than their synthetic counterparts which facilitate vector resistance and intoxicate natural resources. The present study estimated larvicidal activities of the crude and solvent extracts of Acyranthes aspera against the vector of Japanese encephalitis Culex vishnui group under laboratory conditions. Methods: Crude extracts of A. aspera foliage ranging from 0.1% to 0.5% concentrations were examined for larvicidal activity against 1 st to 4 th instars larvae of Cx. vishnui group. Extractions of the active fractions were carried out by means of six different solvents in a non-polar to polar approach viz. petroleum ether, n-hexane, ethyl acetate, chloroform: methanol (1:1 v/v), acetone, and absolute alcohol. Dose dependent mortality was established through graded concentrations ranging from 20 ppm to 100 ppm using the bioactive fractions. Further, determinations of LC 50 and LC 90 values of crude and bioactive fractions were accomplished through log-probit analyses. Statistical justifications of the larvicidal property were established through ANOVA analyses regarding instars, time and concentrations as three completely randomized independent variables. Costing impacts on the non-target water fauna of the bio-active portion were assessed under laboratory conditions. Result : In a 72 hour bioassay experiment with crude extract, the highest mortality was recorded in 0.5% concentration. Acetone extractive was found to exert efficient larvicidal activity amongst all the solvent extractives. Cent per cent mortalities were exhibited by 1 st and 2 nd instars larvae at 48 hours of exposure while 3 rd instars larvae showed 97.32% mortality at 72 hours of exposure with LC 50 value of 32.15 ppm. An obvious dose-dependent mortality was established through regression analyses, as the rate of mortality (Y) was positively correlated with the concentration (X). The non-target populations were primarily non-responsive to plant extracts under study. Conclusion : Extract of A. aspera foliage is of great consequence having appreciable larvicidal activity against Cx. vishnui group . The compound is environment friendly and largely non-toxic to non-target organisms.

Biocontrol efficacy of an organic acid against larval form of Culex quinquefasciatus, Culex vishuni group and Anopheles stephensi

ObjectiveTo estimate the larvicidal activities, if any of glacial acetic acid, an organic acid against Culex quinquefasciatus (Cx. quinquefasciatus), Culex vishuni(Cx. vishuni) group and Anopheles stephensi (An. stephensi). MethodsThe common organic acid, glacial acetic acid at some fixed concentrations(0.1%, 0.2%, 0.3%, 0.4% and 0.5%) were used against third instar larvae of Cx. quinquefasciatus, Cx. vishuni group and An. stephensi in order to investigate the rate of mortality after 24 h, 48 h and 72 h of exposure in laboratory. Results100% mortality of 3rd instar larva of An. stephensi was recorded at 0.5% concentration after 72 h of exposure. The results or regression analysis revealed that the mortality rate (Y) was positively correlate with the period of exposure (X). The value of R2 in all cases was near 1. ConclusionsThe organic chemical may be used efficiently to kill Cx. quinquefasciatus, Cx. vishuni group and An. stephensi. Acid can be applied both in field condition and laboratory condition.

Screening of twenty five plant extracts for larvicidal activity against Culex quinquefasciatus Say (Diptera: Culicidae)

ObjectiveTo determine the larvicidal activity of twenty five plant extracts against Culex quinquefasciatus (Cx. quinquefasciatus). MethodsThe larvicidal activity was determined against the third instar larvae of Cx. quinquefasciatus at 1 000 ppm concentration. Larval mortality was assessed after 24 and 48 h. ResultsThe hexane extracts of Cleistanthus collinus (C. collinus) and Murraya koeingii (M. koeingii) plants showed 100 percent mortality at 24 h bioassay followed by diethyl ether, dichloromethane and ethyl acetate extracts of C. collinus, Leucas aspera (L. aspera), Hydrocotyle javanica (H. javanica), M. koeingii, Sphaeranthus indicus (S. indicus) and Zanthoxylum limonella (Z. limonella) after 48 h exposure. ConclusionsThe results indicate larvicidal activity against Cx. quinquefasciatus and further investigations are needed to elucidate this activity against a wide range of all stages of mosquito species and also the active ingredients of the extract responsible for larvicidal activity should be identified.

Mosquito larvicidal and ovicidal activity of Delonix elata (L.) Gamble against Culex quinquefasciatus Say (Diptera: Culicidae)

ObjectiveTo determine the larvicidal and ovicidal efficacy of different solvent leaf and seed extract of Delonix elata (D. elata) against filariasis vector Culex quinquefasciatus (Cx. quinquefasciatus). MethodsTwenty five early third instar larvae of Cx. quinquefasciatus 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. The ovicidal activity was determined against Cx. quinquefasciatus mosquito to various concentrations ranging from 75-600 mg/L under the laboratory conditions. ResultsAmong five solvent extracts tested the maximum efficacy was observed in the leaf and seed methanol extracts. The LC50 and LC90 values of D. elata against early third instar of Cx. quinquefasciatus were 124.84, 147.86 mg/L and 213.88, 289.43 mg/L, respectively. No mortality was observed in controls. The Chi-square values were significant at P<0.05 level. Among five tested solvent, methanol extract was found to be most effective for ovicidal activity against Cx. quinquefasciatus mosquito. 100% mortality was observed at 375 mg/L . ConclusionsFrom the results it can be concluded the crude extract of D. elata was an excellent potential for controlling Cx. quinquefasciatus mosquito larvae and eggs.

Mosquito larvicidal properties of Ficus benghalensis 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 LC 50 and LC 90 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 An. subpictus mosquito larvae.

Tagetes erecta Linn. and its mosquitocidal potency against Culex quinquefasciatus

Objective To investigate mosquitocidal effects of ethanolic extract of flowers of Tagetes erecta ( T. erecta) and its chloroform and petroleum ether soluble fractions against the larvae of Culex quinquefasciatus ( Cx. quinquefasciatus). Methods The fresh flowers of T. erecta were extracted in cold with ethanol (5.0 L) and after concentration, the ethanol extract was fractionated with chloroform and petroleum ether to afford a brownish syrupy suspension of ethanol extract (50.0 g), petroleum ether soluble fraction (18.6 g) and chloroform soluble fraction (23.8 g). The larvicidal effect of ethanol extract and their solvent fractions were determined by the standard procedure of WHO against different instars of Cx. quinquefasciatus. Results Among the tested samples the chloroform soluble fractions showed the highest toxicity and consequently, the lowest LC50 values (14.14 μg/mL, 17.06 μg/mL, 36.88 μg/mL and 75.48 μg/mL) for all the instars larvae of Cx. quinquefasciatus. The larvae showed comparative tolerance in the course of increasing age and time. Conclusions It can be concluded that the flowers of T. erecta are very effective natural larvicide and could be useful against Cx. quinquefasciatus.

Evaluation of Andrographis paniculata Burm.f. (Family:Acanthaceae) extracts against Culex quinquefasciatus (Say.) and Aedes aegypti (Linn.) (Diptera:Culicidae)

Objective To investigate the larvicidal and ovicidal efficacy of different extracts of Andrographis paniculata (A. paniculata) against Culex quinquefasciatus (Cx. quinquefasciatus) Say and Aedes aegypti (Ae. aegypti) L. (Diptera: Culicidae). Methods Larvicidal efficacy of the crude leaf extracts of A. paniculata with five different solvents like benzene, hexane, ethyl acetate, methanol and chloroform was tested against the early third instar larvae of Cx. quinquefasciatus and Ae. aegypti. The ovicidal activity was determined against two mosquito species to various concentrations ranging from 50-300 ppm under the laboratory conditions. Results The benzene, hexane, ethyl acetate, methanol and chloroform leaf extract of A. paniculata was found to be more effective against Cx. quinquefasciatus than Ae. aegypti. The LC 50 values were 112.19, 137.48, 118.67, 102.05, 91.20 ppm and 119.58, 146.34, 124.24, 110.12, 99.54 ppm respectively. Among five tested solvent, methanol and ethyl acetate crude extract was found to be most effective for ovicidal activity against two mosquito species. The extract of methanol and ethyl acetate exerted 100% mortality at 200 ppm against Cx. quinquefasciatus and at 250 ppm against Ae. aegypti. Conclusions From the results it can be concluded the crude extract of A. paniculata was a potential for controlling Cx. quinquefasciatus and Ae. aegypti mosquitoes.

Larvicidal and repellent properties of some essential oils against Culex tritaeniorhynchus Giles and Anopheles subpictus Grassi (Diptera: Culicidae)

Objective To investigate the larvicidal and repellent properties of essential oils from various parts of four plant species Cymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis and Zingiber officinale against Culex tritaeniorhynchus (Cx. tritaeniorhynchus) and Anopheles subpictus (An. subpictus). Methods Essential oils were obtained by hydro-distillation method. The mosquitoes were reared in the vector control laboratory and twenty five late third instar larvae of Cx. tritaeniorhynchus and An. subpictus were exposed to based on the wide range and narrow range test, essential oil tested at various concentrations ranging from 25 to 250 ppm. The larval mortality was observed after 24 h under the laboratory conditions. The repellent efficacy was determined against two mosquito species at three concentrations viz., 1.0, 2.5 and 5.0 mg/cm 2 under laboratory conditions. Results Results showed all the four plant essential oil produced significant larval mortality against two mosquito species. However, the highest larvicidal activity was observed in the essential oil from Zingiber officinale against Cx. tritaeniorhynchus and An. subpictus with the LC 50 and LC 90 values as 98.83, 57.98 ppm and 186.55, 104.23 ppm, respectively. All the four essential oil shows significant repellency against Cx. tritaeniorhynchus than An. subpictus. Among four essential oil tested the highest repellency was observed in Zingiber officinale, a higher concentration of 5.0 mg/cm 2 provided 100% protection up to 150 and180 min against Cx. tritaeniorhynchus and An. subpictus, respectively. Conclusions In this work, it can be concluded that four essential oils which were distilled from Cymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis and Zingiber officinale showed promising larvicidal and repellent agent against Cx. tritaeniorhynchus and An. subpictus.

Egg hatchability and larvicidal activity of Swertia chirata Buch. - Hams. ex Wall. against Aedes aegypti L. and Culex quinquefasciatus Say.

Crude Swertia chirata extracts (hexane, ethyl acetatem it was 11.4, 17.8 and 23.4 % at 0-6, 6-12 and 12-18 h respectively against Ae. aegypti . The LC50 values for the larvicidal activity of ethyl acetate extract of S. chirata against first, second, third and fourth instar larvae of Cx. quinquefasciatus were 164.91, 220.10, 284.05 and 326.46 ppm and against Ae. aegypti 192.67, 237.30, 339.06 and 329.29 ppm respectively.

Development of Wuchereria bancrofti in Culex quinquefasciatus that survived the exposure of sub-lethal dose of Bacillus sphaericus as larvae

Development of Wuchereria bancrofti in Culex quinquefasciatus emerged from the larvae that survived the exposure of sub-lethal dose of Bacillus sphaericus was examined in the laboratory. Third instar larvae of Cx. quinquefasciatus were treated with B. sphaericus at a sub-lethal dose of 11.35 μg/250 ml. The female mosquitoes that emerged from the survived larvae were fed on microfilaraemic human blood and parasite development was monitored in the fed mosquitoes. Both treated and untreated mosquitoes could ingest microfilaria (mF) equally as there was no significant difference in mF density between them. But, density of developmental stages of the parasite in treated group was significantly lower. Since, there was no mortality of mosquitoes, the lower density of the developmental stages could be attributed to the loss of parasites in the treated mosquitoes. Consequently, the proportion of mosquitoes with infective larvae (L3) and number of L3 were also significantly lower in treated females. Delay in parasite development was also noticed in treated mosquitoes. The present study indicates that B. sphaericus, when applied at sub-lethal dose kills larvae, and in addition, inhibits development of the filarial parasite and consequently reduces L3 yield in adult mosquitoes that emerged from the survived larvae.