Characterization, Formulation, and Toxicity of Plant Oils on Duponchelia fovealis Caterpillars Zeller 1847 (Lepidoptera: Crambidae)

Abstract

This study aimed to determine the chemical composition of ginger Zingiber officinale Roscoe (Zingiberaceae) and soursop Annona muricata Linn (Annonaceae) oils, formulate stable emulsions of these oils separately, as well as neem oil Azadirachta indica A. Juss (Meliaceae), and evaluate the insecticidal activity of these emulsions against Duponchelia fovealis Zeller, 1847 (Lepidoptera: Crambidae). Each stable emulsion contained an oil phase containing ginger, soursop, or neem oil, a fruit polyalcohol–based emulsifier, ethanol, or water. The insecticidal effect of the different oils and formulated emulsions was tested on the first- and second-instar caterpillars of D. fovealis. The majority of the compounds of the ginger essential oil were α-zingiberene (29%), geranial (14.9%), and α-farnesene (12.9%), and soursop oil had a higher percentage of oleic acid (43.73%), linoleic acid (29.51%), and palmitic acid (20.50%). The CL50 values of the soursop, neem, and ginger oils were 0.474, 0.473, and 0.602% for first-instar caterpillars and 2.25, 1.02, and 0.624% for second-instar caterpillars of D. fovealis. The formulated emulsions of ginger, soursop, and neem oils remained stable and exhibited toxicity in the first and second instars of D. fovealis development.