Larvicidal Activity of Some Plants Extracts and Their Partitioned Fractions against Culex quinquefasciatus

Aim: The methanol extracts of fifteen plants and their partitioned fractions were screened for larvicidal activity against the fourth instar of larvae Culex quinquefasciatus, the vector of lymphatic filariasis with a view to identifying the active ones.

Methodology: The plant parts were collected, separately dried and milled. Each powdered material was extracted in methanol at room temperature for 3 days, with agitation. The extract was filtered and concentrated in vacuo. Each extract was tested against the fourth instar larvae of Cx. quinquefasciatus. The methanol extracts were suspended in water and successively partitioned into n-hexane and ethylacetate. Each partitioned fraction was also tested against the fourth instar larvae of Cx. quinquefasciatus.

Results: About fifty six percent (56.3%) of the tested extracts had moderate larvicidal activity after 48 hours. The fruit extract of Thevetia neriifolia and the leaf extracts of Calotropis procera and Solanum macrocarpon were the most active. After partitioning the methanol extracts, each of the plant extracts had one or two highly active partitioned fractions after 48 hours. The n-hexane fractions of S. macrocarpon (0.78 ± 0.03 mg/mL) and Spondias mombin (0.81 ± 0.03 mg/mL) were the most active.

Conclusion: The non-polar fractions of S. macrocarpon and S. mombin were the most active. Purification of these highly active fractions could lead to the isolation of potent larvicidal compounds that could be used in the control of Cx. quinquefasciatus mosquito.