Performance of Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) Reared on Factitious Hosts, Including the Target Host, Ostrinia nubilalis (Lepidoptera: Crambidae)

The performance of the parasitoid Trichogramma ostriniae (Pang et Chen) on eggs of four factitious hosts, Ostrinia nubilalis (Hübner), Sitotroga cerealella (Olivier), Trichoplusia ni (Hübner), and irradiated Ephestia kuhniella (Zeller), is presented. We measured parasitoid longevity, individual and population levels of parasitism, survival of progeny to emergence, and progeny sex ratio for 9 to 11 generations in laboratory colonies. Wasps reared from each source were tested on the source host and on the target host, European corn borer (O. nubilalis). Under the conditions tested, E. kuhniella was a poor host, T. ni and O. nubilalis were good hosts, and S. cerealella was intermediate. We found no evidence that being reared for many generations on an alternate host decreased the performance on the target host, O. nubilalis. Sex ratio was female biased and did not change over time. There may have been an increase in performance of wasps reared on S. cerealella and E. kuhniella over time. We discuss the information gained from different measures of parasitoid performance and the possible causes for variation in performance over time under laboratory conditions.