Abstract: Corcyra cephalonica eggs serve as an essential host for the mass production of the parasitoid wasp Trichogramma chilonis, with the age and fertilization status of host eggs  significantly influencing rearing efficiency. We recorded the duration and frequency of parasitic behaviors (egg surface probing, oviposition, resting and feeding) of female T. chilonis on fertilized and unfertilized C. cephalonica eggs aged 0-96 hours. Results showed that visitation frequency of wasp to host areas declined markedly with increasing egg age (e.g., from 4.80 visits at 0 hour old to 2.70 visits at 48 hours old). Wasps spent consistently longer time probing unfertilized eggs compared to fertilized ones, with a significant difference being observed at 72 hours old (23.36 s vs. 20.02 s). At 24 hours old, oviposition frequency was significantly higher on fertilized eggs than on unfertilized eggs (3.70 vs. 2.95 events). Regardless of fertilization status, mean oviposition frequency was greater in the 0-48-hour-age group (1.90-2.05 events) than in the 72-96-hour-age group (1.60-1.75 events). In contrast, host-feeding behavior exhibited no consistent preference related to egg age or fertilization status. These findings demonstrate that the parasitic behavior of T. chilonis is jointly modulated by host egg age and fertilization status, reflecting a clear preference for younger and fertilized hosts, along with a significant decline in area visitation as host age increases. This study provides an ethological basis for optimizing mass production of T. chilonis through the selection of younger, fertilized C. cephalonica eggs.

Key words: Trichogramma chilonis, Corcyra cephalonica egg, fertilization status, egg age, parasitism, host feeding