Larvicidal activity of aqueous plants extracts on Aedes aegypti larva (first trials)

Abstract

Dengue is an common epidemic disease in tropical and subtropical regions. The elimination of breeding sites and vector control are among the most widely used measures in the fight against the disease. Many strategies have been developed to keep low rates of mosquito populations. Several research studies have been focused on finding natural products with insecticide and larvicide activity that could effectively control these mosquito populations without risks for the human populations and domestic animals. In this work, we have performed a series of bioassays with aqueous extracts of Paraguayan plants: Annona muricata (cherimoya), Bulnesia sarmentoi (palo santo), Melia azederach (paradise), Zanthoxylum chiloperone var. Angustifolium (tembetary hú) and Bixa orellana (uruku) in order to check the effectiveness and activity as larvicide of each plant gainst Aedes aegypti larvae. The larvae were collected in various areas of Asuncion and Great Asuncion during the yellow fever outbreak of 2007. The seeds of A. mucricata (cherimoya or custard apple) showed good larvicidal activity, i.e. at the minimum concentration of 5%, showed lethality against larvae comparable to that observed in positive controls (containing 1% temephos). On the other hand, M. azederach (paradise) and Z. chiloperone (tembetary hú) did not show any larvicidal activity at the same dose and even at higher doses. B. sarmientoi (palo santo) and Bixa orellana (uruku) showed some larvicidal effect killing larva (18%) at 72 hours post-exposure. There was a marked difference in activity between the cherimoya seeds extract and the other extracts tested