Behavioral Response of Eocanthecona furcellata to Volatile Compounds from Frass of Larval Spodoptera litura

The predatory stink bug Eocanthecona furcellata exhibits high efficacy in controlling the tobacco cutworm Spodoptera litura. To investigate the role of S. litura larval frass volatiles in prey location by the predatory stink bug, we tested the behavioral responses of adult E. furcellata to fresh frass (from S. litura larvae reared on tobacco leaves and wheat seedlings) using the Y-tube olfactometer, while also extracting, identifying, and quantifying the frass volatiles. Subsequently, the behavioral responses of adult E. furcellata to individual volatile compound were measured. The results indicated that the frass from 3^rd-instar S. litura larvae fed on tobacco was more attractive to E. furcellata than the frass from larvae fed on wheat. Concurrently, compared with wheat and Chinese cabbage as food sources, the larval frass from tobacco leaves has the highest diversity of compound types and the greatest compound content. Seven individual compounds in larval frass volatiles, including nicotine, neophytadiene, phytol, hexadecanoic acid, linoleic acid, ethyl linolenate, and octadecanoic acid were found to attract E. furcellata, confirms these compounds serve as critical olfactory cues for this predatory bug to localize prey at short range.