Effects of host switching on population rejuvenation and transgenerational fitness in the parasitoid wasp Habrobracon hebetor

Abstract

Host switching, a strategy for population rejuvenation, is essential for sustaining pest control efficacy of parasitic natural enemies. This study evaluated the effects of switching the host of Habrobracon hebetor, reared long-term on Ephestia elutella, to either Plodia interpunctella or Corcyra cephalonica for five consecutive generations. The assessment focused on the parasitoid's subsequent parasitism fitness toward the original host, E. elutella, as well as the across parental and first offspring generations effects. Results showed that host switching significantly increased the number of hosts paralyzed, number of hosts parasitized, and fecundity of the parental generation of H. hebetor on E. elutella. The P. interpunctella–switched group achieved the highest number of parasitized hosts and fecundity, along with significantly extended female longevity. Offspring experiments revealed a shorter larval developmental period in the P. interpunctella–switched population with high percentages of pupal formation and adult emergence. Offspring from this group also showed significantly superior paralysis, parasitism, and fecundity relative to the control and C. cephalonica–switched groups, indicating that fitness benefits from host-switching persist across generations. Overall, P. interpunctella emerged as an optimal alternate host for rejuvenating H. hebetor populations, enhancing parasitic performance and longevity, likely through nutritional or physiological mechanisms. This study provides theoretical and practical guidance for rejuvenating H. hebetor in mass rearing under laboratory conditions, with application value for improving biological control efficacy.