Bioatividade de extratos vegetais sobre os diferentes estágios do ciclo de vida de Aedes (Stegomyia)aegypti (L.1762)

Abstract

Aedes aegypti, is responsible for the transmission of the viruses of the affection and the yellow fever. The development of resistance to the synthetic insecticides and its toxicity take the search of new methods as, for example, the naturals extract use. The present work evaluated the effect of extracts of Cnidosculos phyllacanthus, Coutarea hexandra and Ricinus communis on the different periods of training of the cycle of life of A.aegypti. The tests of plant aticvidad had been carried through in acclimatized room 26°C±2ºC and fotofase of 12 hours. One used rude extracts of trunk of C. phyllacanthus and C. hexandra, concentrated in rotating evaporator and the seed for attainment of the oil of R. communis. In the bioassays the effect had been evaluated larvicide, pupicide and adulticide of these products in function of different concentrations and the time of exposition. Lethal, ovicidal the effect sub and of repellency of oviposição of vegetal extracts was carried through using the lethal concentrations of the larvicide test (CL50 and CL90). The repellency of surface impregnated with the vegetal products was carried through using the dose of 0,5mg/cm2 and 2mg/cm2, in the period of 8 hours. The mortality data had been submitted to the Analysis of Probit for the determination of (CL50 and CL90). Mean values for the preference for oviposition in multiple choice were compared by Friedman test (P <0.05) and no-choice by Kruskal-Wallis (P <0.05). Vegetable oils of C. phyllacanthus and R. communis showed a greater efficiency in controlling larval CL50 = 0.55 ml and CL90 = 3ml and CL50= 0.05 ml and CL90 = 0.50 ml more promising. In the test with pupae, it was found toxic effect of all products containing significant amounts of (CL50 and CL90) after 24 and 48 hours of exposure. To this end sub-lethal concentrations of adulticide and C. phyllacanthus (oil) acted more effectively on the insect. All products through the IOA values showed repellent action on oviposition of A. aegypti, however, the concentrations of the extracts showed little ovicidal activity. Vegetable oils of C. phyllacanthus and R. communis showed more potential in controlling the different stages of the life cycle of this vector.