Vol. 6, Issue 2, Part A (2019)

Author(s): Baraka Samwel, Ester Innocent, Francis Machumi and William N Kisinza

Abstract: The current study evaluated Commiphora merkeri Engl. exudate and its fractions for brine shrimp lethality and mosquito larvicidal activity against Aedes aegypti L, Anopheles gambiae s.s and Culex quinquefasciatus Say. The exudate exhibited larvicidal activity with LC₅₀ of 34.59, 36.54 and 41.07 μg/mL at 24 h against Ae. aegypti, Cx. quinquefasciatus and An. gambiae larvae, respectively. Petroleum ether extract showed activity which was significant different (≥ 95%) when mosquitoes were exposed for 24 and 72 h. Larvae of Ae. aegypti was most susceptible to dichloromethane fraction compared to other species with LC₅₀ of 10.39, 8.82 and 4.31 μg/mL at 24, 48 and 72 hrs, respectively. The exudate showed cytotoxicity to brine shrimps with LC₅₀ of 3.85 μg/mL while petroleum ether fraction exhibited 3.34 μg/mL, followed by dichloromethane (LC₅₀ of 41.52 μg/mL) and aqueous fraction had LC₅₀ >100 μg/mL. The exudate and petroleum ether fraction possess high cytotoxicity to brine shrimps. Further study to identify compounds in dichloromethane fraction which is having moderate cytotoxicity may yield safe insecticidal compounds.