TOXIC EFFECTS OF COASTAL AND MARINE PLANT-EXTRACTS ON MOSQUITO LARVAE

Petroleum-ether and chloroform soluble fractions of methanolic extract s of mangrove/plants (Derris heterophylla, Salvadora persica, Sonnerat ia caseolaris, Clerodendron inerme), seaweeds (Acanthophora muscoides, Microdictyon pseudohapteron), seagrasses (Halophila ovalis, Syringodi um isoetifolium), and a lichen (Umbilicaria aprine) were studied for t heir toxicity against larvae of the mosquito Culex quinquefasciatus. P etroleumether fractions (PE) were more effective than chloroform fract ions (C) in all the nine samples tested. The PE fraction of the seawee d Microdictyon pseudohapteron was found to be most effective with LC50 values of 50 mg L-1 followed by Acanthophora muscoides (62.5 mg L-1). The PE fraction of Syringodium isoetifolium was effective at 450 mg L -1. All other fractions showed activity at between 800 and 2000 mg L-1 . The C fractions of Derris heterophylla, Sonneratia caseolaris, Acant hophora muscoides, Halophila ovalis, Syringodium isoetifolium and Umbi licaria aprine were ineffective even at 2000 mg L-1.