The Stressor Effect of Ethanol and Water Extracts of the Magical Herb Phytolacca dodecandra (Herit) on Life History of Anopheles gambiae (Diptera: Culicidae) Mosquitoes

In this study an informal “after only with control” experimental design was used to evaluate the impact of ethanol and water extracts of leaf and mature green fruits of Phytolacca dodecandraon the life history of An. gambiae. Eighty milligrams of crude extracts of mature green fruits of P. dodecandra was dissolved in 100 millilitres of rain water and the solution serially diluted to concentrations of 80, 40, 20, 10, 5, and 2.5 mg/100 mL. The diluents were then added into five groups of six sets of larval rearing trays each measuring 21 cm × 15 cm × 8 cm. This was repeated for leaves of P. dodecandra, Azadirachta indica leaves, and Deltamethrin. Each tray received 100 freshly laid An. gambiae eggs. Climatic conditions within insectaries were 29°C~30°C, 70%~80% relative humidity, and 12:12, L: D photoperiod. The experiments were replicated four times. The extracts impacted the life history of exposed mosquitoes irrespective of parts of P. dodecandra used or dose. Parts of plant used impacted mortality significantly (p < 0.001) compared to dose (p > 0.05). Water extract was more potent than ethanol extracts (p < 0.05). Though toxicity reduced with time, longevity of the extracts was dose dependent and significantly influenced mortality (p < 0.001). Lethal doses (LC50) were relatively lower (doses of ≤ 4.6) with small lower and upper 95% CI. It is concluded that extracts of P. dodecandra impacts the life cycle of An. gambiae mosquitoes critically interfering with their development.