Effects of host age, parasitoid age, and superparasitism on reproductive fitness of Macrocentrus cingulum (Hymenoptera: Braconidae), a larval polyembryonic parasitoid.

BACKGROUND Macrocentrus cingulum Brischke is a polyembryonic endoparasitoid of Ostrina furnacalis Guenée larvae. The interactions between parasitoid age, host age, and superparasitism could affect reproductive attributes such as parasitism rate and brood size, changing the efficiency of mass-rearing programs producing M. cingulum. RESULTS The parasitism rate of M. cingulum on O. furnacalis larvae was significantly affected by host age, parasitoid age, and their interactions. Macrocentrus cingulum preferred parasitizing host larvae at late 3rd instars over early or late 4th instars. Older female parasitoids (5, 6, or 7 days after emergence) caused higher parasitism levels on three tested host ages than did younger parasitoids, likely because M. cingulum is synovigenic and the older females had a greater oocyte load in their oviducts. The age of O. furnacalis larvae significantly affected brood size but did not change the developmental time of M. cingulum. Late stage, third instars of O. furnacalis supported the largest parasitoid broods. Both brood size and body size of offspring were influenced significantly by superparasitism. Doubly-stung hosts produced most parasitoid offspring while the body size was smallest. CONCLUSION In summary, late 3rd instars of O. furnacalis larvae, combined with adult female parasitoids five or more days old and with two stings were optimal for mass rearing of M. cingumum in the laboratory. © 2025 Society of Chemical Industry.