Insecticidal activity of plant extracts and essential oils of bleed water against the bean weevil

Abstract

This study was aimed to evaluate the toxicity of semi-purified fractions (FS) (Hexane - FH, ethyl acetate - FAE, ethanol/water - FEA) and the essential oils of the bark and leaves of Croton urucurana against the bean weevil (Callosobruchus maculatus). The insects were subjected to concentration-mortality bioassays of the FS, to determine the LC50. Subsequently, the effect of the FS was evaluated, through the method of vaporization and multiple choices. The fumigation action was evaluated using the essential oils, and the population growth was assessed using the FAE-leaf. All FS were toxic for C. maculatus, however, the lowest LC50as well as a higher mortality in the vaporization method were obtained with the FAE-leaf. The essential oils from the bark caused an insect mortality greater than 80%.The least preferred rate of insects was obtained with the beans treated with FAE-bark while the beans treated with FAE-leaf reduced the population growth of the C. maculatus. Thus, we conclude that the semi-purified fractions and the essential oils of bark and leaves of C. urucurana interfere with the survival and biology of C. maculatus. Key words: Euphorbiaceae, Plant extracts, repellency, bean weevil.