Insecticidal and growth regulating activity of crude leaf extracts of Cassia occidentalis L. (Caesalpinaceae) against the urban malaria vector, Anopheles stephensi Liston (Diptera: Culicidae)

Objective: To investigate insecticidal and growth regulating activity of crude leaf extracts of\udCassia occidentalis L. (Caesalpinaceae) against the urban malaria vector, Anopheles stephensi\udListon. (Diptera: Culicidae).\udMethods: Larvicidal activity was studied against third instar larvae for 24 h at concentrations\udof 62.5, 125.0, 250.0, 500.0, 1 000.0, 2 000.0, 4 000.0 and 8 000.0 mg/L. The effect on development and\udgrowth of immature mosquitoes was studied at concentrations of 125.0, 250.0 and 500.0 mg/L and\udwas assessed by growth index. Adulticidal activity on topical application was studied on test\uddosages of 0.01, 0.05, 0.10, 0.25 and 0.50 µg per newly emerged unfed adult female mosquito.\udResults: Larvicidal activity was poor, not proportional to concentration and LC 50 values were\udabove the acceptable dose of 10 mg/L. Potential growth regulating activity was observed and the\udgrowth index was 277.5, 111.0 and 27.5 times less than control, respectively. Average larval pupal\udtransformation was 5.8, 4.3 and 96.0 times greater than pupal adult transformation in hexane, 5.0,\ud4.3 and 48.4 in ethyl acetate, and 4.8, 4.2 and 10.2 in methanol extract, respectively. Adulticidal\udactivity was the highest in ethyl acetate, followed by hexane and methanol extract with LD50\udvalues of 0.23, 0.32 and 0.64 µg/female mosquito, respectively.\udConclusions: The crude leaf extracts of Cassia occidentalis studied showed poor larvicidal,\udpotential growth regulating and a moderate level of adulticidal activity