Fitness-related changes in laboratory populations of the egg parasitoid Trichogramma galloi and the implications of rearing on factitious hosts

In this study, we used the specialist egg parasitoid Trichogramma galloi Zucchi, 1988 (Hymenoptera: Trichogrammatidae) to test whether development over multiple generations on a factitious host would later influence performance on the target pest. We also investigated possible adaptations to laboratory rearing conditions by monitoring over 50 and 46 generations life history traits of T. galloi populations maintained on the natural [Diatraea saccharalis (Fabr., 1794) (Lepidoptera: Crambidae)] and factitious host [Ephestia kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae)], respectively. We detected a possible sign of adaptation to rearing conditions in early generations on the emergence of the population maintained on the natural host. We also verified a reduction in fecundity and emergence of parasitoids maintained on the factitious host when fitness was evaluated on the natural host, confirming the prediction that the use of factitious hosts can lower fitness on the target pest. The importance of these results for the effectiveness of biological control programs is discussed.