Azadirachta indica LEAF AND SEED EXTRACTS AS POTENTIAL LARVICIDES OF Anopheles gambiae FROM NORTHWEST, NIGERIA

Abstract

Malaria has been a major problem accounting for thousands of death in Nigeria. It is spread by female Anopheles mosquito which injects the Plasmodium parasite into the human system. Chemical control has been the mainstay in control of mosquitoes for decades which have proven to be toxic to humans, animals and the environment in addition to widespread resistance. This study investigated the potential of phytochemicals (Azadirachta indica leaf and seed extracts) in the control of mosquito larvae. The plant leaves were extracted using solvents of varying polarities starting from least polar to most polar (hexane, chloroform, butanol, ethanol, methanol/aqueous) respectively while the seed was extracted using hexane. Varying concentrations (5000ppm, 6000ppm, 7000ppm, 8000ppm, 9000ppm and 10,000ppm) were administered to 20 larvae each, water/acetone were used as control. The result of phytochemicals screening revealed the presence of various compounds of which tritepenes were only detected in butanol extract.  Mortality was recorded after 24 hours. The result showed no significant difference (P>0.05) when hexane, chloroform, ethanol, methanol/aqueous leaf extracts and hexane seed extracts were compared with control while there was significant difference (P<0.05) when butanol leaf extract was compared with control. There was significant decrease (P<0.05) in the level of glucose estimated in the susceptible larvae when compared with resistant and control larvae. The result of DNA estimation showed no significant difference (P>0.05) between all comparisons. In conclusion, butanolic extract of Azadirachta indica leaf displayed a promising larvicidal properties which might be due to the presence of triterpenes which may have interference with the normal metabolic processes and could be explored for possible novel bio-insecticide for the control of mosquitoes.