Abstract

IN VITRO EVALUATION OF THE BIOCIDAL EFFECTS OF PLANT EXTRACTS FROM KINSHASA (DR-CONGO) ON MOSQUITO LARVAE

Musuyu M.D.*, Maloueki U., Wat’Senga F.T., Dani A.N., Manzambi Z.E., Sita L.B., Lami N.J., Kimbeni M.T., Cimanga K.R., Fruth B., Schoetz K., Vlietinck A.J. and Pieters L.

ABSTRACT

In the course of our studies on the valorization of plants used by the Nkundo people in Democratic Republic of Congo (DRCongo), we have carried out a preliminary screening of 50 aqueous extracts (at a standard concentration of 1%) from 35 plants for their larvicidal potential on late third or early fourth instar larvae of Culex quinquefasciatus. It resulted that 7 ethanol extracts from 4 plants including Crossopteryx febrifuga (Cf) root bark, Penianthus longifolius root bark, Piper guineense fruit, root and stem barks (PG) and Quassia africana stem and root bark (QA) were found to be most active with larval mortality rates ranging from 85-100% after 24 h exposure. Piper guinsense leaves produced 58.33±2.89% mortality. In addition to these 4 most active samples, 7 corresponding 80% ethanol extracts were prepared by maceration. In total, 14 ethanol extracts were tested at 10 concentrations (20 - 0.4 mg/ mL) on late third or early fourth instar larvae of 3 types of larvae [Aedes aegypti (AA), Anopheles gambiae (AG) and Culex quinquefasciatus (CQ)]. Based on the 24 h LC50 values, the ethanol extracts were found more active than their aqueous counterparts; AG and CQ were more sensitive. Most interesting extracts displayed LC50 values < 0.039 mg/mL. They included ethanolic extracts from fruits, root bark and stem bark of PG towards both AG and CQ as well as from root bark and stem bark of QA towards CQ. In conclusion, the most active extracts may constitute a basis for the production of eco-friendly and biodegradable plant-based insecticides. They can be used solely or in potentially synergistic combinations with other known plant-based insecticides.

Keywords: Nkundo people, larvicidal activity, plant extracts, Bandundu.