Potencial do óleo essencial de Líppia alba (Mill) N. E. Brown. no controle de Meloidogyne javanica em plantas alface

Abstract

In the face of the damages and damages that the agrochemicals cause, there is an incessant search for methods that aim at the control of phytopathogens in a sustainable way, being the essential oils (OE) extracted from plant species are efficient in inhibiting the nematicidal activity. The objective of this work was to evaluate the in vitro and in vivo nematicide action of Lippia alba essential oil on juveniles of Meloidogyne javanica in lettuce (Lactuca sativa). EO was extracted from the leaves by hydrodistillation in a Clevenger apparatus. A bioassay was prepared using 1000 μl of an aqueous solution containing 10% (v / v) Tween® 20, 1000 μl of M. javanica J2, containing 50 individuals, containing the EO at different concentrations (4, 8, 16 And 32 μL / ml) plus the control, with four replications, in a completely randomized experimental design. They were evaluated after 24 and 48 hours, respectively. In vivo assay, 357 individuals were inoculated between eggs and juveniles J2 of M. javanica per plant, the concentrations tested were the same, in vitro, with eight replicates per treatment. 100 ml of the solution containing 10 ml of Tween® 20, 990 ml of deionized water and the respective concentrations of 4, 8, 16 and 32 μL of L. alba oil were added to the soil after 45 days of inoculation. In the determination of the dry mass of the roots and part area the plants were placed in paper bags and taken to the stove at 40°C. The L. alba OE presented nematode and nematicidal activity, the concentration of 8 μL / ml decreased infestation by 70% and the concentration of 32 μL / ml was responsible for causing 100% immobility of juveniles. The nematicidal effect was verified, with the second evaluation after 48 hours, it was verified that 70% and 100%. It was observed that in the concentration of 0 (control), which presented 257 galls and 87% galls in the concentration 16 μL L-1, when compared to the control. Egg and egg mass numbers decreased with increasing concentration. In the two largest concentrations, 16 and 32 μL L-1 reduced the number of egg masses per gram of roots by 49 and 56%, and 51 and 55%, respectively, relative to the control. It can be observed that the essential oil of L. alba presents nematicidal effects on the mortality and immobility of juveniles of the second stage (J2) of M. Javanica, in vitro and in vivo.