Résumé
Objective: The larvicidal potential of Andrographis echioides and Cadaba trifoliata leaf extract was tested separately against larvae of Aedes aegypti and also tested mixture of these two plant extracts for synergistic effect against the larvae. Methods: Pulverized leaves of A. echioides and C.trifoliata were subjected separately to soxhlet extraction using organic solvent of ethanol. These two plant extracts were examined separately against 4th instar larvae of A.aegypti with gradually increasing concentration i.e. from 50 to 250mg/l using WHO protocol. To observe the synergistic effect, extracts of these two plants were mixed at different concentrations and tested against the larva. The 24h LC50 values of individual plant extract and mixed extracts were determined following probit analysis. Results: A. echioides extract shows more lethal effect than C. trifoliata extract towards larvae of A.aegypti with LC50 values of 108.3 and 123.4 mg/l, respectively, whereas , synergistic larvicidal effect was found to be even more effective than the plant extract tested separately in terms of LC50 being 68.3 mg/l. Conclusions: From the results, it is evident that synergistic effect of A. echioides and C. trifoliata can be considered as a more powerful arsenal for the control of A.aegypti than the usage of these two extract separately.
Résumé
OBJECTIVE@#To assess the larvicidal and egg hatching inhibition property of the leaf essential oil of Coccinia indica (C. indica) against Anopheles stephensi (An. stephensi).@*METHODS@#The larvicidal potential of C. indica leaf essential oil was evaluated against 1st, 2nd, 3rd and 4th instars larvae of An. stephensi using WHO protocol. The 24h LC(50) and LC(90) values of the essential oil were determined following probit analysis. The egg hatching inhibition activity was also tested at 10, 20, 40, and 60 mg/L. The IC(50) value of essential oil was determined against eggs of An. stephensi.@*RESULTS@#The essential oil extracted from C. indica possessed excellent larvicidal and egg hatching inhibition activity against An. stephensi. The bioassays showed LC(50)-LC(90) of 54.3-140.3, 65.5-155.6, 86.8-180.7 and 95.3-192.6 for 1st, 2nd, 3rd, and 4th larval instars, respectively. The 50% egg hatching inhibition concentration (IC(50)) was noted at 16.5 mg/L.@*CONCLUSIONS@#The present finding suggest that the C. indica leaf essential oil provided an excellent potential for controlling An. stephensi mosquito at earlier stage of their life cycle.