Larvicidal activity of Dialium cochinchinense (Velvet Tamarind) fruit extract against mosquito larvae

Dialium cochinchinense (Velvet tamarind) fruit is a medicinal plant important for management of diarrhoea, fever, microbial infections, palpitations, stomatitis and toothache. This study evaluated the larvicidal activities of D. cochinchinense fruit extract against mosquito larvae. Larvae were collected from Lugbu FCT-Nigeria and introduced into 10, 20, 40, 80 and 100 mg/mL of D. cochinchinense fruit extract. Azadirachtin (10 mg/mL), DMSO and Triton X100 were used as controls. Larvae mortality was monitored at 24, 48 and 72 hours. For pupae and mosquito emergence rate, the larvae were reared in the laboratory to pupae stage, and the rate of mosquito emergence was monitored. Larvae mortality ranged from 0.00±0.00% to 25.56±12.62% after 24 hours, increasing to 29.21±13.34% at 100 mg/mL after 48 hours and 52.06±24.66% at 100 mg/mL after 72 hours. Azadirachtin produced 61.11±34.69% mortality after 24 hours and 100% mortality after 48 and 72 hours respectively, while Triton X-100 (1%) caused complete mortality. The extract showed low to moderate pupaecidal activity. After 24 hours, mortality ranged from 0.00% to 15.28±2.41%, while after 48 hours the highest mortality was 29.76±18.33% at 40 mg/mL. Azadirachtin caused 9.70±1.01% pupae mortality at 24 hours and 19.39±1.05% at 48 and 72 hours, whereas Triton X-100 caused 100% pupae mortality throughout the experiment. At 24 hours, mosquito emergence ranged from 10.32±3.52% to 90.48±16.50%. Prolonged exposure did not increase inhibitory effects on mosquito emergence rate, with 20 mg/mL achieving 100% emergence at 48 and 72 hours respectively, while 10 mg/mL produced 94.44±9.62% emergence. D. cochinchinense extract demonstrated greater potential on larval mortality than inhibition of mosquito emergence. Aqueous Dialium cochinchinense fruit extract demonstrated promising mosquito-control potential, particularly by its larvicidal activities.