Larvicidal Activity of Piper guineense and Spilanthes mauritiana Crude-Powder Against Anopheles gambiae and Culex quinquefasciatus in Kilifi District, Kenya

Field trials were conducted in Kilifi District, Kenya on the activity of Piper guineense and Spilanthes mauritiana powders against field populations of Anopheles gambiae s.l. and Culex quinquefasciatus larvae. Pools containing mosquito larvae were sampled and larval populations determined before and after application of plant powders. Four doses, 0.5,1.0,1.5 and 2.0 g L super(-1), were used in the trials and larval mortality monitored after 24,48 and 72 h. After 24 h, P. guineense powder at 0.5 g L super(-1) gave larval mortalities of 18.8 and 23.6% for An. gambiae s.l. and Cx. quinquefasciatus, respectively. At 2.0 g L super(-1), mortalities at the same duration were 80.1 and 67.8% for An. gambiae s.l. and Cx. quinquefasciatus, respectively. In S. mauritiana treated larvae, in 24 h, mortality of 20% was obtained for both An. gambiae s.l. and Cx. quinquefasciatus at 0.5 g L super(-1). For 2.0 g L super(-1), at the same duration, mortalities of 98 and 100% for An. gambiae s.l. and Cx. quinquefasciatus, respectively, were recorded. After 72 h, at the highest dose, S. mauritiana and P. guineense powders induced larval mortalities of 100, 99.8%, in An. gambiae s.l. and 100, 97.7% in Cx. quinquefasciatus, respectively. At 24 h, the LD sub(50) values were 0.98 and 0.76 g L super(-1) for S. mauritiana and P. guineense, respectively, for An. gambiae s.l. Similarly, LD sub(50) of 0.85 and 0.68 g L super(-1), respectively, for Cx. quinquefasciatus were obtained. Piper guineense and S. mauritiana derived powder yielded promising results and merit further study as potential larval control agents.