Applying plant oils to control fall armyworm (Spodoptera frugiperda) in corn

Abstract

Corn (Zea mays) is one of the world's main agricultural crops, and Spodoptera frugiperda (J. E. Smith) is its most important pest. In order to find natural controlling alternatives, this study aimed to determine the effect of plant oils on the feeding preference of first- and second-instar caterpillars. The experimental design was completely randomized in a 6 x 5 factorial combination (turmeric, clove, palmarosa, tea tree, common juniper, and neem oils) at five concentrations (0, 25, 50, 100, and 200 muL mL-1), plus a control consisting of acetone 100.0%, with five replicates per treatment. Twenty-five-day-old corn leaf sections received the corresponding treatments in addition to the control and were deposited along orthogonal axes in an arena arranged in Petri dishes. Ten 1st instar caterpillars were released at the center of the plates, and results were obtained after 8h and 24h from the release, based on the number of caterpillars found on each treatment. For 1st instar caterpillars, the best results were observed for clove and palmarosa, which negatively influenced caterpillar feeding activity in both evaluation periods, followed by turmeric oil, which showed the same effectiveness in the last period only. For second-instar caterpillars, the best effects were observed for neem, turmeric, palmarosa, and clove oil in the first evaluation period. Furthermore, the effectiveness of the first three oils was maintained in the second evaluation period. These results emphasize the potential capability of plant oils when used in management programs against this pest, in which the oils of turmeric, clove and palmarosa showing the best controlling potential of this pest from the lowest concentration corresponding to 25 muL mL-1.