Análise comparativa do potencial inseticida dos óleos essenciais das folhas e frutos de Melaleuca leucadendra sobre a traça das crucíferas (Plutella xylostella)

Abstract

The objective of this work is to investigate the insecticidal potential of the essential oils of the different parts of Melaleuca leucadendra, on the cruciferous moth, Plutella xylostella, contributing to the studies aimed at botanical insecticides. To this end, we analyzed comparatively the insecticidal activity of the leaf and fruit oils of M. leucadendra on P. xylostella by means of the larvicide toxicity bioassays and embryocid toxicity, also comparing its results with the insecticide Azamax® Commercial. The OEs obtained for leaves and fruits of M. leucadendra, presented yield of 0.28% ± 0.05 and 0.18% ± 0.03 respectively, being all in acceptable standards for plants producing essential oils. As the majority constituent of these oils, sesquiterpene (E)-nerolidol in concentrations above 90% was characterized in both parts. The results obtained through the larvicide toxicity Bioassay showed a lethal mean concentration of 0.15 mg/mL and 0.17 mg/mL for the oils of the fruits and leaves of M. leucadendra, respectively, but not statistically different. For the experiments carried out on the embryonic phase of P. xylostella, again there was no statistical difference, showing LC50 of 0.23 mg/mL and 0.28 mg/mL for leaf and fruit oils, respectively. Both essential oils, as well as the majority constituent, presented higher toxicity on the cruciferous moth than the commercial insecticide Azamax® (LC50 = 2,75 mg/mL and LC50 = 2,57 mg/mL on the larvae and eggs, respectively), showing promising in the control of the Plutella xylostella.