Olfactory attraction of egg parasitoids to virgin females of noctuid stemborers

To locate hosts, egg parasitoids rely on infochemicals of the adult host stage, e.g. pheromones, rather than cues emitted by the inconspicuous egg themselves. Here, we show that three different egg parasitoid species the scelionids Telenomus busseolae Gahan and Telenomus isis Polaszek and the trichogrammatid Trichogramma bournieri Pintureau & Babault were attracted to both calling and non-calling females of the noctuids Busseola fusca (Fuller), Sesamia calamistis (Hampson) and Sesamia nonagrioides (Lefebvre). In Y-tube olfactometer experiments this study revealed a preference of all three parasitoids for non-calling (general odors of virgin females) and calling moth (sex pheromone) over the control (clean air), and for calling over the non-calling moth. However, the three parasitoids were equally attracted to calling moth of B. fusca and S. calamistis indicating low host specificity. The findings indicated that all three parasitoids used the pheromones released by the calling moth in host finding. It is suggested that the low host specificity may affect egg parasitism of the target pest in crop fields.