Efficacy of Limonia acidissima L. (Rutaceae) leaf extract on larval immatures of Culex quinquefasciatus Say 1823

OBJECTIVE@#To investigate the role of leaf extract of Limonia acidissima L. (Rutaceae) as a biocontrol agent against the larval form of Culex quinquefasciatus, and characterization of bioactive component responsible for larvicidal activity.@*METHODS@#Larval mortality of mosquito species was observed after 24, 48 and 72 hours of exposure to different concentrations of aqueous extract, solvent extract and subsequently bioactive compound. The bioactive compound was subjected to IR and GC-MS analysis.@*RESULTS@#Mortality rate at 3% concentration of crude extract were highest (90%) amongst all concentrations tested and subsequently highest (95%) mortality was achieved in chloroform: methanol extract at 100 ppm concentrations. IR and GC-MS analysis of bioactive compound revealed the presence of steroid compound which may act as larvicide.@*CONCLUSIONS@#The chloroform: methanol extract of mature leaves of Limonia acidissima was found to exhibit considerable mosquito larvicidal activity against Culex quinquefasciatus.

Synergistic effect of Croton caudatus (fruits) and Tiliacora acuminata (flowers) extracts against filarial vector Culex quinquefasciatus

Objective:To investigate the synergistic effect of crude and solvent extract of Croton caudatus (C. caudatus ) (fruits) and Tiliacora acuminata (T. acuminata) (flowers) against the larval form of Culex quinquefasciatus (Cx. quinquefasciatus). Methods: Crude and solvent [chloroform:methanol (1:1 v/v), benzene and ethyl acetate] extracts of two plants, C. caudatus (fruits) and T. acuminata (flowers) were examined separately against filarial vector Cx. quinquefasciatus larvae with gradually increasing concentration i.e. from 0.1%to 0.5%of crude extract and 25 ppm to 75 ppm of solvent extracts. To observe the synergistic effect, if any, extracts of these two plant parts were mixed at different concentrations and treated against mosquito larvae. Phytochemical analyses of extracts of both the plant parts were carried out. Results: In a 72-h bioassay experiment with plant extracts, highest mortalities were recorded at 0.5% (crude) and 75 ppm (solvent) concentration for fruits of C. caudatus and flowers of T. acuminata individually. For synergistic effect, only 0.2%of the mixture of these two crude extracts and 75 ppm concentration of chloroform:methanol (1:1 v/v) and ethyl acetate extracts showed 100%mortality after 24 h and 48 h of exposure respectively. Conclusions:In the field of mosquito control, insecticides of plant origin may serve as suitable alternative to the toxic chemicals. Some secondary metabolites in combination may be responsible for better larvicidal activity.