Chemical Characterization and Application of the Essential Oils from Chenopodium ambrosioides and Philodendron bipinnatifidum in the Control of Diabrotica speciosa (Coleoptera: Chrysomelidae)

The compositions of essential oils from Chenopodium ambrosioides L. and Philodendron bipinnatifidum Schott were determined, and the their potential effects on the nutrition and mortality of Diabrotica speciosa were studied. The extraction of the oils was performed by hydrodistillation (2 h) using a modified Clevenger apparatus and the oils were subsequently subjected to analysis by gas chromatography/flame ionization detector (CG/FID) and gas chromatography/mass spectrometry (GC-MS). A completely randomized design with five treatments and four replications was adopted. The bean plants were sprayed with solutions of the oils dissolved in aqueous Tween 80 solutions at concentrations of 0 (water + Tween 80), 0.5%, 1.0%, 1.5% and 2.0% and then furnished to the insects with no choice available. Seven days after the application, the percentage of leaves with injury, degree of defoliation, the preference index for consumption and the percent of mortality of insects were evaluated. Neither of the essential oils caused a reduction in foliar injury, but antifeeding activity was observed, causing reduced feeding and increasing the mortality of adult D. speciosa insects.