Larvicidal Activity of Native Plant Extracts From the Araripe National Forest on Aedes aegypti

Abstract

Aiming to verify the insecticidal potential of 16 native plants from the Araripe National Forest (ANFO) on L3 Aedes aegypti larvae in laboratory conditions, were researches performed in controlled conditions of temperature, air relative humidity and photophase, in a type B.O.D. climatized chamber, executed in period from August/2016 to May/2017. The adopted experimental design was completely randomized, represented by ethanolic extracts obtained from 16 native plants, besides the witness without application and with pyriproxyfen as chemical insecticide, conducted with four replicates in each plant extract. The application of the extracts was performed only once, and at 24, 48 and 72 hours, after the infestation, was determined the effects of the extracts on larval mortality. The extracts of Amargoso, oil’tree, Lacre, Cajui, Louro smelling, Field Rosemary, Murici truthful, Janaguba and laranjinha provoke mortality above of 90% to the larvae of Aedes aegypti after three days of exposure, in the dose of 50 mL of the extracts. After 24 hours of exposure, the ethanolic extracts from barks and leaves of Field Rosemary and of laranjinha killed all the larvae. On the other hand, the extracts with higher larvicide potential were evaluated at different doses (i.e., 12.5, 25, and 50 mL/L) in a 9 × 3 factorial scheme, with four replicates. The ethanolic extract of the leaves of Louro smelling is the most efficient, because in any dosage it eliminates all the larvae of Aedes aegypti, thus demonstrating to be an excellent vegetable larvicide in the control of this vector after three days of exposure, whereas the bark extract of the oil’tree is the least effective. The alkaloids and flavonoids are present in the leaves of the Louro smelling.