The effect of an alkaloidal fraction from the stem bark of Artabotrys odoratissimus R. Br. on larvae of the mosquito vector of lymphatic filariasis, Culex quinquefasciatus Say, was investigated. Concentrations of 10, 20, 40, 80, 160 and 320 ppm were tested in the laboratory against larvae of various ages. A general increase in lethal concentration 50 (LC50) values from the second to fourth instars was observed. Based on overlapping confidence intervals (CIs), the LC50 value following 12 h of exposure was lowest for the second instar (59.2 ppm) and was significantly different from that recorded for the fourth instar (110.4 ppm). LC50 values decreased significantly with time (from 12 to 24 h after treatment) in all the instars. These results indicate the potential utility of the A. odoratissimus extract as a mosquito larvicidal agent, and further research is recommended.
