Larvicidal Effect of Ipomoea stolonifera on Laboratory-Reared and Field-Collected Aedes aegypti Mosquitoes in Enugu, Nigeria

Comparative study of the effects of methanolic crude extracts of Ipomoea stolonifera on 4th instars larvae of both laboratory-reared and field-collected Aedes aegypti were carried out. The 4th instars larvae of laboratory-reared and the field-collected A. aegypti mosquitoes were exposed to 5000mg/L, 2000 mg/L, 1000 mg/L, 500 mg/L, 100 mg/L, 50 mg/L of the extract. The solvent for the extract, dimethyl sulphoxide (DMSO) was used as control. The results indicate concentration dependent mortalities and significant differences (P<0.05) in the mean percentage mortality between the laboratory-reared and field-collected Aedes mosquitoes. The mortality rate due to the extract was found to be less in the field collected A. aegypti (LC50 = 2.81 +/- 0.14; LCI = 2.55; UCI = 3.11) than the laboratory-reared ones (LC50=1.24 +/- 0.09; LCI = 1.07; UCI = 1.43) after 24 h exposure. The median larvicidal concentration LC50 values of the extract were 1.24 +/- 0.09g/L and 2.81 +/- 0.14g/L for 4th instars larvae of both laboratory-reared and field-collected mosquito larvae respectively. Further research is recommended on the isolation of the active ingredients of I. stolonifera for use in effective control of mosquito.