Effects of prolonged mass rearing on life history traits of Habrobracon hebetor (Hymenoptera: Braconidae)

Long-term mass rearing of parasitoids under laboratory conditions may affect their quality. We studied the quality of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) reared for more than 20 generations (G) using two-sex life table parameters. We found that G2 had the longest pre-adult development time (12.4 d) and the highest fecundity (1304.00 eggs/female) compared with the other generations. While no significant differences in the intrinsic rate of increase (r) and net reproductive rate (R0) were found among G4, G6, G8, G15, and G20, the highest values of r (0.3273 day−1) and R0 (436.28 eggs/individual) as well as the shortest mean generation time (T) were observed in G10. In addition, significant differences in sex ratio (F/F + M) were observed among different generations, ranging from 17% in G2 to 60% in G10. These results suggest that up to a certain number of generations (G10), the quality of H. hebetor significantly increased without adding field-collected parasitoids or changing the factitious host. To maintain the quality of the colony beyond this point, it should be rejuvenated by periodically adding field-collected individuals.