Plasticity of Body Growth and Development in Two Cosmopolitan Pupal Parasitoids

1. Pachycrepoideus vindemiae and Trichopria drosophilae are cosmopolitan pupal parasitoids of Drosophilidae that attack the invasive Drosophila suzukii. This study investigated one aspect of their phenotypic plasticity – host acceptance and offspring fitness on 25 Drosophila species in a phylogenetic framework. Each parasitoid’s key biological and ecological traits were compared among the different host species. 2. Results demonstrate that both parasitoids successfully parasitized and developed from all tested host species. Although the parasitoids’ efficiency and offspring fitness varied among host species, effects on life-history characteristics or ecological traits appeared to be unrelated to the phylogenetic position of tested host species. 3. Both parasitoids benefited from attacking larger hosts, with body size of emerging progeny positively correlated to host size and an increased fecundity (mature egg load) of female wasps. Achieving larger body size came at no significant costs in immature development time. 4. The results show remarkable levels of phenotypic plasticity in the parasitoids’ body growth and development, which is discussed with respect to their potential for host range expansion.