Toxicity of the Hexane Fraction of Fruits and Seeds of Ricinus communis to Caterpillars of the Spodoptera Complex

Abstract

The objective of this work was to evaluate the effect of the hexane fraction of the crude extract of the fruits and seeds of Ricinus communis (HFFSRC) on eggs of Spodoptera cosmioides and Spodoptera frugiperda and on caterpillars of Spodoptera eridania, S. frugiperda, and S. cosmioides, under laboratory conditions through topical application and ingestion, as well as to identify the compounds in the hexane fraction through high-performance chromatography (HPLC-ESI-Q-TOF-MS/MS). To do so, three bioassays were conducted: (1) the effect of HFFSRC at 2% (20,000 mg·mL−1) on eggs of S. cosmioides and S. frugiperda, (2) the lethal effect of HFFSRC at 2% applied topically, and (3) the lethal effect of HFFSRC at 2% applied to soybean-leaf discs on first-, second-, third-, and fourth-instar caterpillars of the three insect species. It was found that 2% HFFSRC had an ovicidal effect on S. frugiperda and S. cosmioides, completely reducing larvae hatching and the insecticidal effect for the four instars of the three insect species when applied topically and on food. Five compounds were identified in the HFFSRC: three flavonoids, one ricinoleic acid, and one cinnamic acid. HFFSRC at 2% had an acute ovicidal and insecticidal effect on caterpillars of the studied species, configuring itself as a potential insecticide.