Ovicidal activity of aqueous crude leaf extract of Cymbopogon citratus, lemon grass, (poaceae) against Culex quinquefasciatus mosquito (Diptera culicidae)

Abstract

Despite the use of inorganic mosquito repellents and insecticides for controlling adult mosquito population, the breeding grounds of mosquitoes are still persistent. This study investigated the ovicidal potential of aqueous crude leaf extract of Cymbopogon citratus on the wild strains of Culex quinquefasciatus mosquito at five (5) test concentrations in logarithmic range of 62.5-1,000 ppm plus a control (0.00 ppm) each quadruple replicated and had egg raft (containing approximately 150 C. quinquefasciatus eggs). Plant bioactivity of the aqueous crude leaf extract of C. citratus and its acute ovicidal activity on C. quinquefasciatus mosquito coupled with the water quality parameters of the test media were analyzed. Phytochemicals screened revealed strong presence of tannins, cardiac glycosides, phenol and resins. The 48-hrs acute ovicidal activity showed dose-dependent mortality; the highest (150.00 ± 0.00) mortality recorded at 1,000 ppm test concentration with median lethal concentration (48hr-LC₅₀) of 186.21 ppm. Water quality in test media analyzed were significantly different (p<0.05) except temperature which did not differ significantly (p>0.05) compared to the control. It can be inferred that the use of C. citratus leaf which is readily available, biodegradable and environmentally friendly could halt the egg-stage reproductive cycle and thus serve as biocide against C. quinquefasciatus mosquito.

Keywords: Plant bioactive; C. citrates; acute; ovicidal; C. quinquefasciatus