Attraction of Chelonus insularis to host and host habitat volatiles during the search of Spodoptera frugiperda eggs

Egg parasitoids use different strategies than do larval parasitoids to locate hosts. The wasp Chelonus insularis Cresson is a key egg parasitoid of the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), one of the main insect pests of maize (Zea mays L.). Using a Y-glass tube olfactometer, in this study we determined the roles of chemical cues from host and host habitats used by C. insularis when they search for FAW eggs. We found that C. insularis females were attracted to volatiles emitted by host egg masses, host females (i.e., sex pheromone), and maize seedlings with and without FAW eggs. The responses of the parasitoids to host and maize seedling volatiles increased after their first oviposition experience, making it possible for females to discriminate between maize seedlings with and without FAW eggs. The information generated in this study may be useful in the development of future biological control programs of S. frugiperda using C. insularis in either augmentation or conservation approaches.