Behavioral effect of frass extract from Spodoptera litura on Eocanthecona furcellata and its chemical components analysis

To clarify the role of volatiles from Spodoptera litura larval frass in mediating prey location by Eocanthecona furcellata, this study examined the behavioral effect of the frass extract on E. furcellata and analyzed its chemical composition.

Solvent extraction was used to obtain the frass extract from third instar larvae of S. litura, and the behavioral responses of adult E. furcellata to the extract were assessed using a Y-tube olfactometer. Then the compounds in the crude extract were identified and quantified using gas chromatography-mass spectrometry (GC-MS) and gas chromatography (GC), while the electrophysiological responses of E. furcellata to the extract were determined via gas chromatography coupled with electroantennographic detection (GC-EAD).

The results showed that both female and male E. furcellata were attracted to the frass extract, and ten compounds were identified from it. Among these, eight elicited GC-EAD responses in both sexes of E. furcellata: L-nicotine, neophytadiene, hexadecanoic acid, phytol, linoleic acid, ethyl linolenate, octadecanoic acid, and 1, 5, 9-Trimethyl-12-isopropyl-4, 8, 13-cyclotetradecatriene-1, 3-diol.

The results suggest that both tobacco residue-associated odors in the frass and intrinsic frass volatiles, especially the eight compounds identified above, significantly contribute to the prey localization of E. furcellata via olfactory cues.