Olfactory Response and Preference of Telenomus dignus and Trichogramma chilonis to Chilo sacchariphagus

To clear the relationship between host-searching behavior of the egg parasitoids Trichogramma chilonis Ishii and Telenomus dignus (Gahan) and chemicals compounds from different parts of their host Chilo sacchariphagus Bojer, olfactory responses bioassays were carried out with crude extracts of scales, abdominal tips and eggs from C. sacchariphagus respectively by the Y-tube olfactometer. The preference bioassays of egg parasitoids to C. sacchariphagus were also tested by offering the single egg mass to one female of T. chilonis and one female of Te. dignus . Results of olfactory responses showed that females of T. chilonis and Te. dignus responded differentially to crude extracts of different parts from C. sacchariphagus . Their olfactory responses were closely related to the concentration of the extracts. Results of host preference bioassays showed that the egg exposure frequency and the number of eggs parasitized by Te. dignus were significantly more than those of T. chilonis. Also, more Te. dignus could parasitize C. sacchariphagus eggs faster . It was suggested that Te. dignus had a stronger response and preference for C. sacchariphagus, which may be partly because it had a strong host speciality.